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Sample records for highly sensitive magnetic

  1. High-Sensitivity Measurement of Density by Magnetic Levitation.

    Science.gov (United States)

    Nemiroski, Alex; Kumar, A A; Soh, Siowling; Harburg, Daniel V; Yu, Hai-Dong; Whitesides, George M

    2016-03-01

    This paper presents methods that use Magnetic Levitation (MagLev) to measure very small differences in density of solid diamagnetic objects suspended in a paramagnetic medium. Previous work in this field has shown that, while it is a convenient method, standard MagLev (i.e., where the direction of magnetization and gravitational force are parallel) cannot resolve differences in density mm) because (i) objects close in density prevent each other from reaching an equilibrium height due to hard contact and excluded volume, and (ii) using weaker magnets or reducing the magnetic susceptibility of the medium destabilizes the magnetic trap. The present work investigates the use of weak magnetic gradients parallel to the faces of the magnets as a means of increasing the sensitivity of MagLev without destabilization. Configuring the MagLev device in a rotated state (i.e., where the direction of magnetization and gravitational force are perpendicular) relative to the standard configuration enables simple measurements along the axes with the highest sensitivity to changes in density. Manipulating the distance of separation between the magnets or the lengths of the magnets (along the axis of measurement) enables the sensitivity to be tuned. These modifications enable an improvement in the resolution up to 100-fold over the standard configuration, and measurements with resolution down to 10(-6) g/cm(3). Three examples of characterizing the small differences in density among samples of materials having ostensibly indistinguishable densities-Nylon spheres, PMMA spheres, and drug spheres-demonstrate the applicability of rotated Maglev to measuring the density of small (0.1-1 mm) objects with high sensitivity. This capability will be useful in materials science, separations, and quality control of manufactured objects.

  2. Recent trends in high spin sensitivity magnetic resonance

    Science.gov (United States)

    Blank, Aharon; Twig, Ygal; Ishay, Yakir

    2017-07-01

    Magnetic resonance is a very powerful methodology that has been employed successfully in many applications for about 70 years now, resulting in a wealth of scientific, technological, and diagnostic data. Despite its many advantages, one major drawback of magnetic resonance is its relatively poor sensitivity and, as a consequence, its bad spatial resolution when examining heterogeneous samples. Contemporary science and technology often make use of very small amounts of material and examine heterogeneity on a very small length scale, both of which are well beyond the current capabilities of conventional magnetic resonance. It is therefore very important to significantly improve both the sensitivity and the spatial resolution of magnetic resonance techniques. The quest for higher sensitivity led in recent years to the development of many alternative detection techniques that seem to rival and challenge the conventional ;old-fashioned; induction-detection approach. The aim of this manuscript is to briefly review recent advances in the field, and to provide a quantitative as well as qualitative comparison between various detection methods with an eye to future potential advances and developments. We first offer a common definition of sensitivity in magnetic resonance to enable proper quantitative comparisons between various detection methods. Following that, up-to-date information about the sensitivity capabilities of the leading recently-developed detection approaches in magnetic resonance is provided, accompanied by a critical comparison between them and induction detection. Our conclusion from this comparison is that induction detection is still indispensable, and as such, it is very important to look for ways to significantly improve it. To do so, we provide expressions for the sensitivity of induction-detection, derived from both classical and quantum mechanics, that identify its main limiting factors. Examples from current literature, as well as a description of

  3. Magnetic probe array with high sensitivity for fluctuating field.

    Science.gov (United States)

    Kanamaru, Yuki; Gota, Hiroshi; Fujimoto, Kayoko; Ikeyama, Taeko; Asai, Tomohiko; Takahashi, Tsutomu; Nogi, Yasuyuki

    2007-03-01

    A magnetic probe array is constructed to measure precisely the spatial structure of a small fluctuating field included in a strong confinement field that varies with time. To exclude the effect of the confinement field, the magnetic probes consisting of figure-eight-wound coils are prepared. The spatial structure of the fluctuating field is obtained from a Fourier analysis of the probe signal. It is found that the probe array is more sensitive to the fluctuating field with a high mode number than that with a low mode number. An experimental demonstration of the present method is attempted using a field-reversed configuration plasma, where the fluctuating field with 0.1% of the confinement field is successfully detected.

  4. Highly sensitive detection of protein biomarkers via nuclear magnetic resonance biosensor with magnetically engineered nanoferrite particles.

    Science.gov (United States)

    Jeun, Minhong; Park, Sungwook; Lee, Hakho; Lee, Kwan Hyi

    Magnetic-based biosensors are attractive for on-site detection of biomarkers due to the low magnetic susceptibility of biological samples. Here, we report a highly sensitive magnetic-based biosensing system that is composed of a miniaturized nuclear magnetic resonance (NMR) device and magnetically engineered nanoferrite particles (NFPs). The sensing performance, also identified as the transverse relaxation (R2) rate, of the NMR device is directly related to the magnetic properties of the NFPs. Therefore, we developed magnetically engineered NFPs (MnMg-NFP) and used them as NMR agents to exhibit a significantly improved R2 rate. The magnetization of the MnMg-NFPs was increased by controlling the Mn and Mg cation concentration and distribution during the synthesis process. This modification of the Mn and Mg cation directly contributed to improving the R2 rate. The miniaturized NMR system, combined with the magnetically engineered MnMg-NFPs, successfully detected a small amount of infectious influenza A H1N1 nucleoprotein with high sensitivity and stability.

  5. High sensitive LPFG magnetic field sensor based on dual-peak resonance

    Science.gov (United States)

    Gu, Zhengtian; Ling, Qiang; Lan, Jinlong; Gao, Kan

    2017-11-01

    A high sensitivity magnetic field sensor based on magnetic-fluid-clad LPFG structure with dual peak resonance is presented and experimentally investigated. Based on coupled mode theory, the sensing principle of this sensor is originated from the sensibility of the dual peak based LPFG to the environment refractive index. In experiment, a dual peak interval change was available to 38 nm with a magnetic field strength varying from 0 to 12 mT when the temperature was 17.3 °C, and the dual peak interval displays a cubic polynomial dependence with the magnetic field strength at the low field regime. The sensitivity of this sensor to the magnetic field can be available to 4.08 nm/mT, and it is one order and two orders of magnitude higher than that of the sensors based on MSM and SMS fiber structure, respectively. The novel sensor has many advantages of simple technology, structure stability and high sensitivity.

  6. Highly Sensitive and Reproducible SERS Performance from Uniform Film Assembled by Magnetic Noble Metal Composite Microspheres.

    Science.gov (United States)

    Niu, Chunyu; Zou, Bingfang; Wang, Yongqiang; Cheng, Lin; Zheng, Haihong; Zhou, Shaomin

    2016-01-26

    To realize highly sensitive and reproducible SERS performance, a new route was put forward to construct uniform SERS film by using magnetic composite microspheres. In the experiment, monodisperse Fe3O4@SiO2@Ag microspheres with hierarchical surface were developed and used as building block of SERS substrate, which not only realized fast capturing analyte through dispersion and collection under external magnet but also could be built into uniform film through magnetically induced self-assembly. By using R6G as probe molecule, the as-obtained uniform film exhibited great improvement on SERS performance in both sensitivity and reproducibility when compared with nonuniform film, demonstrating the perfect integration of high sensitivity of hierarchal noble metal microspheres and high reproducibility of ordered microspheres array. Furthermore, the as-obtained product was used to detect pesticide thiram and also exhibited excellent SERS performance for trace detection.

  7. Malaria pigment crystals as magnetic micro-rotors: key for high-sensitivity diagnosis

    CERN Document Server

    Butykai, A; Kocsis, V; Szaller, D; Bordacs, S; Tatrai-Szekeres, E; Kiss, L F; Bota, A; Vertessy, B G; Zelles, T; Kezsmarki, I

    2012-01-01

    The need to develop new methods for the high-sensitivity diagnosis of malaria has initiated a global activity in medical and interdisciplinary sciences. Most of the diverse variety of emerging techniques are based on research-grade instruments, sophisticated reagent-based assays or rely on expertise. Here, we suggest an alternative optical methodology with an easy-to-use and cost-effective instrumentation, which takes advantage of the unique properties of malaria pigment revealed in the present study. Malaria pigment, also called hemozoin, is an insoluble microcrystalline form of heme. We found that these crystallites show remarkable magnetic and optical anisotropy distinctly from any other components of blood. In suspensions they can simultaneously act as magnetically driven micro-rotors and spinning polarizers. These properties can gain fundamental importance not only in the diagnosis of malaria and in therapies, where hemozoin is considered as drug target or immune modulator, but generally in the magnetic ...

  8. Atomic magnetic gradiometer for room temperature high sensitivity magnetic field detection

    Science.gov (United States)

    Xu, Shoujun [Berkeley, CA; Lowery, Thomas L [Belmont, MA; Budker, Dmitry [El Cerrito, CA; Yashchuk, Valeriy V [Richmond, CA; Wemmer, David E [Berkeley, CA; Pines, Alexander [Berkeley, CA

    2009-08-11

    A laser-based atomic magnetometer (LBAM) apparatus measures magnetic fields, comprising: a plurality of polarization detector cells to detect magnetic fields; a laser source optically coupled to the polarization detector cells; and a signal detector that measures the laser source after being coupled to the polarization detector cells, which may be alkali cells. A single polarization cell may be used for nuclear magnetic resonance (NMR) by prepolarizing the nuclear spins of an analyte, encoding spectroscopic and/or spatial information, and detecting NMR signals from the analyte with a laser-based atomic magnetometer to form NMR spectra and/or magnetic resonance images (MRI). There is no need of a magnetic field or cryogenics in the detection step, as it is detected through the LBAM.

  9. Development of a highly-sensitive Penning ionization electron spectrometer using the magnetic bottle effect

    Energy Technology Data Exchange (ETDEWEB)

    Ota, Masahiro; Ishiguro, Yuki; Nakajima, Yutaro; Miyauchi, Naoya; Yamakita, Yoshihiro, E-mail: yamakita@uec.ac.jp [Department of Engineering Science, Graduate School of Informatics and Engineering The University of Electro-Communications 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585 (Japan)

    2016-02-01

    This paper reports on a highly-sensitive retarding-type electron spectrometer for a continuous source of electrons, in which the electron collection efficiency is increased by utilizing the magnetic bottle effect. This study demonstrates an application to Penning ionization electron spectroscopy using collisional ionization with metastable He*(2{sup 3}S) atoms. Technical details and performances of the instrument are presented. This spectrometer can be used for studies of functional molecules and assemblies, and exterior electron densities are expected to be selectively observed by the Penning ionization.

  10. Magnetic Separation-Assistant Fluorescence Resonance Energy Transfer Inhibition for Highly Sensitive Probing of Nucleolin.

    Science.gov (United States)

    Li, Yan-Ran; Liu, Qian; Hong, Zhangyong; Wang, He-Fang

    2015-12-15

    For the widely used "off-on" fluorescence (or phosphorescence) resonance energy transfer (FRET or PRET) system, the separation of donors and acceptors species was vital for enhancing the sensitivity. To date, separation of free donors from FRET/PRET inhibition systems was somewhat not convenient, whereas separation of the target-induced far-between acceptors has hardly been reported yet. We presented here a novel magnetic separation-assistant fluorescence resonance energy transfer (MS-FRET) inhibition strategy for highly sensitive detection of nucleolin using Cy5.5-AS1411 as the donor and Fe3O4-polypyrrole core-shell (Fe3O4@PPY) nanoparticles as the NIR quenching acceptor. Due to hydrophobic interaction and π-π stacking of AS1411 and PPY, Cy5.5-AS1411 was bound onto the surface of Fe3O4@PPY, resulting in 90% of fluorescence quenching of Cy5.5-AS1411. Owing to the much stronger specific interaction of AS1411 and nucleolin, the presence of nucleolin could take Cy5.5-AS1411 apart from Fe3O4@PPY and restore the fluorescence of Cy5.5-AS1411. The superparamagnetism of Fe3O4@PPY enabled all separations and fluorescence measurements complete in the same quartz cell, and thus allowed the convenient but accurate comparison of the sensitivity and fluorescence recovery in the cases of separation or nonseparation. Compared to nonseparation FRET inhibition, the separation of free Cy5.5-AS1411 from Cy5.5-AS1411-Fe3O4@PPY solution (the first magnetic separation, MS-1) had as high as 25-fold enhancement of the sensitivity, whereas further separation of the nucleolin-inducing far-between Fe3O4@PPY from the FRET inhibition solution (the second magnetic separation, MS-2) could further enhance the sensitivity to 35-fold. Finally, the MS-FRET inhibition assay displayed the linear range of 0.625-27.5 μg L(-1) (8.1-359 pM) and detection limit of 0.04 μg L(-1) (0.05 pM) of nucleolin. The fluorescence intensity recovery (the percentage ratio of the final restoring fluorescence intensity

  11. Design of a Matching Network for a High-Sensitivity Broadband Magnetic Resonance Sounding Coil Sensor.

    Science.gov (United States)

    Zhang, Yang; Teng, Fei; Li, Suhang; Wan, Ling; Lin, Tingting

    2017-10-27

    The magnetic resonance sounding (MRS) technique is a non-invasive geophysical method that can provide unique insights into the hydrological properties of groundwater. The Cu coil sensor is the preferred choice for detecting the weak MRS signal because of its high sensitivity, low fabrication complexity and low cost. The tuned configuration was traditionally used for the MRS coil sensor design because of its high sensitivity and narrowband filtering. However, its narrow bandwidth may distort the MRS signals. To address this issue, a non-tuned design exhibiting a broad bandwidth has emerged recently, however, the sensitivity decreases as the bandwidth increases. Moreover, the effect of the MRS applications is often seriously influenced by power harmonic noises in the developed areas, especially low-frequency harmonics, resulting in saturation of the coil sensor, regardless of the tuned or non-tuned configuration. To solve the two aforementioned problems, we propose a matching network consisting of an LC broadband filter in parallel with a matching capacitor and provide a design for a coil sensor with a matching network (CSMN). The theoretical parameter calculations and the equivalent schematic of the CSMN with noise sources are investigated, and the sensitivity of the CSMN is evaluated by the Allan variance and the signal-to-noise ratio (SNR). Correspondingly, we constructed the CSMN with a 3 dB bandwidth, passband gain, normalized equivalent input noise and sensitivity (detection limit) of 1030 Hz, 4.6 dB, 1.78 nV/(Hz)(1/2) @ 2 kHz and 3 nV, respectively. Experimental tests in the laboratory show that the CSMN can not only improve the sensitivity, but also inhibit the signal distortion by suppressing power harmonic noises in the strong electromagnetic interference environment. Finally, a field experiment is performed with the CSMN to show a valid measurement of the signals of an MRS instrument system.

  12. Magnetic loading of tyrosinase-Fe3O4/mesoporous silica core/shell microspheres for high sensitive electrochemical biosensing.

    Science.gov (United States)

    Wu, Shuo; Wang, Hainan; Tao, Shengyang; Wang, Chan; Zhang, Lihui; Liu, Zhiguang; Meng, Changgong

    2011-02-07

    A new protocol is proposed for magnetic loading and sensitive electrochemical detection of phenol via the tyrosinase cross-linked mesoporous magnetic core/shell microspheres. The mesoporous magnetic microspheres, characterized by transmission electron microscopy, N(2) adsorption/desorption isotherms, and magnetic curve displays high capacity for enzyme immobilization and strong magnetism to adhere to the magnetic electrode surface without any additional adhesive reagent. The biosensor exhibits a wide linear response to phenol ranging from 1.0×10(-9) to 1.0×10(-5) M, a high sensitivity of 78 μA mM(-1), a low detection limit of 1 nM, and a fast response rate (less than 5s). The proposed method is simple, rapid, inexpensive and convenient in electrode renewal, which is recommended as a promising experimental platform for wider applications in biosensing. Copyright © 2010 Elsevier B.V. All rights reserved.

  13. High sensitivity tracer imaging of iron oxides using magnetic particle imaging

    Energy Technology Data Exchange (ETDEWEB)

    Goodwill, Patrick [University of California, Dept. of Bioengineering, Berkeley, CA (United States); Konkle, Justin; Lu, Kuan; Zheng, Bo [UC Berkeley (UCSF), Joint Graduate Group in Bioengineering, CA (United States); Conolly, Steven [University of California, Berkeley Bioengineering, Electrical Engineering, and Computer Science, CA (United States)

    2014-07-01

    Full text: Magnetic Particle Imaging (MPI) is a new tracer imaging modality that is gaining significant interest from NMR and MRI researchers. While the physics of MPI differ substantially from MRI, it employs hardware and imaging concepts that are familiar to MRI researchers, such as magnetic excitation and detection, pulse sequences, and relaxation effects. Furthermore, MPI employs the same superparamagnetic iron oxide (SPIO) contrast agents that are sometimes used for MR angiography and are often used for MRI cell tracking studies. These SPIOs are much safer for humans than iodine or gadolinium, especially for Chronic Kidney Disease (CKD) patients. The weak kidneys of CKD patients cannot safely excrete iodine or gadolinium, leading to increased morbidity and mortality after iodinated X-ray or CT angiograms, or after gadolinium-MRA studies. Iron oxides, on the other hand, are processed in the liver, and have been shown to be safe even for CKD patients. Unlike the 'black blood' contrast generated by SPIOs in MRI due to increased T2 dephasing, SPIOs in MPI generate positive, 'bright blood' contrast. With this ideal contrast, even prototype MPI scanners can already achieve fast, high-sensitivity, and high-contrast angiograms with millimeter-scale resolutions in phantoms and in animals. Moreover, MPI shows great potential for an exciting array of applications, including stem cell tracking in vivo, first-pass contrast studies to diagnose or stage cancer, and inflammation imaging in vivo. So far, only a handful of prototype small-animal MPI scanners have been constructed worldwide. Hence, MPI is open to great advances, especially in hardware, pulse sequence, and nanoparticle improvements, with the potential to revolutionize the biomedical imaging field. (author)

  14. Shape-changing magnetic assemblies as high-sensitivity NMR-readable nanoprobes

    Science.gov (United States)

    Zabow, G.; Dodd, S. J.; Koretsky, A. P.

    2015-04-01

    Fluorescent and plasmonic labels and sensors have revolutionized molecular biology, helping visualize cellular and biomolecular processes. Increasingly, such probes are now being designed to respond to wavelengths in the near-infrared region, where reduced tissue autofluorescence and photon attenuation enable subsurface in vivo sensing. But even in the near-infrared region, optical resolution and sensitivity decrease rapidly with increasing depth. Here we present a sensor design that obviates the need for optical addressability by operating in the nuclear magnetic resonance (NMR) radio-frequency spectrum, where signal attenuation and distortion by tissue and biological media are negligible, where background interferences vanish, and where sensors can be spatially located using standard magnetic resonance imaging (MRI) equipment. The radio-frequency-addressable sensor assemblies presented here comprise pairs of magnetic disks spaced by swellable hydrogel material; they reversibly reconfigure in rapid response to chosen stimuli, to give geometry-dependent, dynamic NMR spectral signatures. The sensors can be made from biocompatible materials, are themselves detectable down to low concentrations, and offer potential responsive NMR spectral shifts that are close to a million times greater than those of traditional magnetic resonance spectroscopies. Inherent adaptability should allow such shape-changing systems to measure numerous different environmental and physiological indicators, thus providing broadly generalizable, MRI-compatible, radio-frequency analogues to optically based probes for use in basic chemical, biological, medical and engineering research.

  15. Perspectives for sensitivity enhancement in proton-detected solid-state NMR of highly deuterated proteins by preserving water magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Chevelkov, Veniamin, E-mail: shevelkov@fmp-berlin.de; Xiang, ShengQi; Giller, Karin; Becker, Stefan; Lange, Adam [Max-Planck-Institut für biophysikalische Chemie (MPI-bpc) (Germany); Reif, Bernd [Technische Universität München (TUM), Munich Center for Integrated Protein Science (CIPS-M), Department Chemie (Germany)

    2015-02-15

    In this work, we show how the water flip-back approach that is widely employed in solution-state NMR can be adapted to proton-detected MAS solid-state NMR of highly deuterated proteins. The scheme allows to enhance the sensitivity of the experiment by decreasing the recovery time of the proton longitudinal magnetization. The method relies on polarization transfer from non-saturated water to the protein during the inter-scan delay.

  16. A Novel High Sensitivity Sensor for Remote Field Eddy Current Non-Destructive Testing Based on Orthogonal Magnetic Field

    Directory of Open Access Journals (Sweden)

    Xiaojie Xu

    2014-12-01

    Full Text Available Remote field eddy current is an effective non-destructive testing method for ferromagnetic tubular structures. In view of conventional sensors’ disadvantages such as low signal-to-noise ratio and poor sensitivity to axial cracks, a novel high sensitivity sensor based on orthogonal magnetic field excitation is proposed. Firstly, through a three-dimensional finite element simulation, the remote field effect under orthogonal magnetic field excitation is determined, and an appropriate configuration which can generate an orthogonal magnetic field for a tubular structure is developed. Secondly, optimized selection of key parameters such as frequency, exciting currents and shielding modes is analyzed in detail, and different types of pick-up coils, including a new self-differential mode pick-up coil, are designed and analyzed. Lastly, the proposed sensor is verified experimentally by various types of defects manufactured on a section of a ferromagnetic tube. Experimental results show that the proposed novel sensor can largely improve the sensitivity of defect detection, especially for axial crack whose depth is less than 40% wall thickness, which are very difficult to detect and identify by conventional sensors. Another noteworthy advantage of the proposed sensor is that it has almost equal sensitivity to various types of defects, when a self-differential mode pick-up coil is adopted.

  17. Ultra-High Field NMR and MRI—The Role of Magnet Technology to Increase Sensitivity and Specificity

    Directory of Open Access Journals (Sweden)

    Ewald Moser

    2017-08-01

    Full Text Available “History, of course, is difficult to write, if for no other reason, than that it has so many players and so many authors.” – P. J. Keating (former Australian Prime MinisterStarting with post-war developments in nuclear magnetic resonance (NMR a race for stronger and stronger magnetic fields has begun in the 1950s to overcome the inherently low sensitivity of this promising method. Further challenges were larger magnet bores to accommodate small animals and eventually humans. Initially, resistive electromagnets with small pole distances, or sample volumes, and field strengths up to 2.35 T (or 100 MHz 1H frequency were used in applications in physics, chemistry, and material science. This was followed by stronger and more stable (Nb-Ti based superconducting magnet technology typically implemented first for small-bore systems in analytical chemistry, biochemistry and structural biology, and eventually allowing larger horizontal-bore magnets with diameters large enough to fit small laboratory animals. By the end of the 1970s, first low-field resistive magnets big enough to accommodate humans were developed and superconducting whole-body systems followed. Currently, cutting-edge analytical NMR systems are available at proton frequencies up to 1 GHz (23.5 T based on Nb3Sn at 1.9 K. A new 1.2 GHz system (28 T at 1.9 K, operating in persistent mode but using a combination of low and high temperature multi-filament superconductors is to be released. Preclinical instruments range from small-bore animal systems with typically 600–800 MHz (14.1–18.8 T up to 900 MHz (21 T at 1.9 K. Human whole-body MRI systems currently operate up to 10.5 T. Hybrid combined superconducting and resistive electromagnets with even higher field strength of 45 T dc and 100 T pulsed, are available for material research, of course with smaller free bore diameters. This rather costly development toward higher and higher field strength is a consequence of the inherently low

  18. (YIP 09) Domain Engineered Magnetoelectric Thin Films for High Sensitivity Resonant Magnetic Field Sensors

    Science.gov (United States)

    2011-12-01

    study the the model del and bett   n Table 1 – PZT sol-gel and data (me er fits were     red is Actua films on pla an square er obtained by l...nditions to timal opera t models aro 3 process v ollowing mo ias ditions (sho ickness. Re by any plas get high dep ting conditio und the pre...and Magnetic Characterization of Core-Shell Silicon Carbo Nitride Coated Carbon Nanotubes ”, Mater. Lett. 63, 2435-2438 (2009). 2. S. Priya, J. Ryu

  19. Ultra-high field NMR and MRI - the role of magnet technology to increase sensitivity and specificity

    Science.gov (United States)

    Moser, Ewald; Laistler, Elmar; Schmitt, Franz; Kontaxis, Georg

    2017-08-01

    "History, of course, is difficult to write, if for no other reason, than that it has so many players and so many authors." - P. J. Keating (former Australian Prime Minister) Starting with post-war developments in nuclear magnetic resonance (NMR) a race for stronger and stronger magnetic fields has begun in the 1950s to overcome the inherently low sensitivity of this promising method. Further challenges were larger magnet bores to accommodate small animals and eventually humans. Initially, resistive electromagnets with small pole distances, or sample volumes, and field strengths up to 2.35 T (or 100 MHz 1H frequency) were used in applications in physics, chemistry, and material science. This was followed by stronger and more stable (NbTi based) superconducting magnet technology typically implemented first for small-bore systems in analytical chemistry, biochemistry and structural biology, and eventually allowing larger horizontal-bore magnets with diameters large enough to fit small laboratory animals. By the end of the 1970s, first low-field resistive magnets big enough to accommodate humans were developed and superconducting whole-body systems followed. Currently, cutting-edge analytical NMR systems are available at proton frequencies up to 1 GHz (23.5 T) based on Nb3Sn at 1.9 K. A new 1.2 GHz system (28 T) at 1.9 K, operating in persistent mode but using a combination of low and high temperature multi-filament superconductors is to be released. Preclinical instruments range from small-bore animal systems with typically 600 - 800 MHz (14.1 - 18.8 T) up to 900 MHz (21 T) at 1.9 K. Human whole-body MRI systems currently operate up to 10.5 T. Hybrid combined superconducting and resistive electromagnets with even higher field strength of 45 T dc and 100 T pulsed, are available for material research, of course with smaller free bore diameters. This rather costly development towards higher and higher field strength is a consequence of the inherently low and, thus

  20. A highly sensitive quartz crystal microbalance immunosensor based on magnetic bead-supported bienzymes catalyzed mass enhancement strategy.

    Science.gov (United States)

    Akter, Rashida; Rhee, Choong Kyun; Rahman, Md Aminur

    2015-04-15

    A highly sensitive quartz crystal microbalance (QCM) immunosensor based on magnetic bead-supported bienzyme catalyzed mass enhanced strategy was developed for the detection of human immunoglobulin G (hIgG) protein. The high sensitive detection was achieved by increasing the deposited mass on the QCM crystal through the enhanced precipitation of 4-chloro-1-naphthol (CN) using higher amounts of horseradish peroxidase (HRP) and glucose oxidase (GOx) bienzymes attached on the magnetic beads (MB). The protein A (PA) and capture antibody (monoclonal anti-human IgG antibody produced in mouse, Ab1)-based QCM probe and the detection antibody (anti-human IgG antibody produced in goat, Ab2)-based MB/HRP/GOx bienzymatic bioconjugates were characterized using scanning electron microscope, transmission electron microscope, cyclic voltammetry, and electrochemical impedance spectroscopy techniques. Under the optimized experimental condition, the linear range and the detection limit of hIgG immunosensor were determined to be 5.0pg/mL-20.0ng/mL and 5.0±0.18pg/mL, respectively. The applicability of the present hIgG immunosensor was examined in hIgG spiked human serum samples and excellent recoveries of hIgG were obtained. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Cascaded silicon-on-insulator double-ring sensors operating in high-sensitivity transverse-magnetic mode.

    Science.gov (United States)

    Jiang, Xianxin; Ye, Junjun; Zou, Jun; Li, Mingyu; He, Jian-Jun

    2013-04-15

    We demonstrate ultrahigh-sensitivity silicon photonic sensors based on two cascaded double-ring resonators operating in transverse-magnetic mode. Both wavelength interrogation and intensity interrogation methods are experimentally investigated and the sensitivities reached 24,300 nm/RIU and 2430 dB/RIU, respectively. We also show that the double-ring sensors can be simply cascaded to realize simultaneous detection of multiple species, which is very promising for low-cost array applications.

  2. Quantification of the effect of inhomogeneous magnetization or irregularity in shape on the measurement of remanent magnetization with a high-sensitivity multifunctional spinner magnetometer

    Science.gov (United States)

    Kodama, Kazuto

    2017-04-01

    Quantitative assessments of the effect of inhomogeneous magnetization or irregularity in shape on the measurement of remanent magnetization were made experimentally and theoretically. Experiments were performed on artificial and natural samples, using a novel type of high-sensitivity spinner magnetometer (Kodama, G-cubed, 2016). The spinner has a wide dynamic range from 10-10-10-4 Am2 and a resolution of 10-11 Am2, incorporating two unique functions: a mechanism for adjusting flexibly the spacing between the sensor and the spinning axis, and a capability of measuring not only the fundamental component (5 Hz) but also the second (10 Hz) and the third (15 Hz) harmonic components. The former enabled the measurement of samples in any shape sized 10-50 mm, and the latter allowed the measurement of waveforms containing the harmonics leading to the analyses of their FFT spectrum. Numerical simulations using finite element method (FEM) were performed for assessing the effect of shape irregularity on the measured remanent magnetization. The effect of the heterogeneous magnetization was evaluated using a small dipole-simulating coil and a mini-core specimen of volcanic rock, and measured their magnetization by repositioning at different distances off the spinning axis. The effect of the offset was assessed in terms of the amplitude of the fundamental wave and the harmonics versus the amount of the offset. The measured amplitudes, without exception, increased with the amount of the offset, and their relationship was well approximated by a polynomial curve consisting of the second- to forth-order terms. This suggests that the contribution from the higher-order harmonic components could be represented in the form of a non-linear function of the offset distance. Measurements by a conventional spinner also demonstrated a similar increasing curve, but in association with a smaller increase rate and relatively large errors. The smaller increase rate is most likely due to its high

  3. Magnetic resonance guided high-intensity focused ultrasound mediated hyperthermia improves the intratumoral distribution of temperature-sensitive liposomal doxorubicin.

    Science.gov (United States)

    de Smet, Mariska; Hijnen, Nicole M; Langereis, Sander; Elevelt, Aaldert; Heijman, Edwin; Dubois, Ludwig; Lambin, Philippe; Grüll, Holger

    2013-06-01

    The aim of this study was to investigate the intratumoral distribution of a temperature-sensitive liposomal carrier and its encapsulated compounds, doxorubicin, and a magnetic resonance (MR) imaging contrast agent after high-intensity focused ultrasound (HIFU)-mediated hyperthermia-induced local drug release. (111)In-labeled temperature-sensitive liposomes encapsulating doxorubicin and [Gd(HPDO3A) (H(2)O)] were injected intravenously in the tail vein of rats (n = 12) bearing a subcutaneous rhabdomyosarcoma tumor on the hind leg. Immediately after the injection, local tumor hyperthermia (2 × 15 minutes) was applied using a clinical 3 T MR-HIFU system. Release of [Gd(HPDO3A)(H(2)O)] was studied in vivo by measuring the longitudinal relaxation rate R(1) with MR imaging. The presence of the liposomal carriers and the intratumoral distribution of doxorubicin were imaged ex vivo with autoradiography and fluorescence microscopy, respectively, for 2 different time points after injection (90 minutes and 48 hours). In hyperthermia-treated tumors, radiolabeled liposomes were distributed more homogeneously across the tumor than in the control tumors (coefficient of variation(hyp, 90 min) = 0.7 ± 0.2; coefficient of variation(cntrl, 90 min) = 1.1 ± 0.2). At 48 hours after injection, the liposomal accumulation in the tumor was enhanced in the hyperthermia group in comparison with the controls. A change in R(1) was observed in the HIFU-treated tumors, suggesting release of the contrast agent. Fluorescence images showed perivascular doxorubicin in control tumors, whereas in the HIFU-treated tumors, the delivered drug was spread over a much larger area and also taken up by tumor cells at a larger distance from blood vessels. Treatment with HIFU hyperthermia not only improved the immediate drug delivery, bioavailability, and intratumoral distribution but also enhanced liposomal accumulation over time. The sum of these effects may have a significant contribution to the therapeutic

  4. Highly sensitive and selective lateral flow immunoassay based on magnetic nanoparticles for quantitative detection of carcinoembryonic antigen.

    Science.gov (United States)

    Liu, Fangming; Zhang, Honglian; Wu, Zhenhua; Dong, Haidao; Zhou, Lin; Yang, Dawei; Ge, Yuqing; Jia, Chunping; Liu, Huiying; Jin, Qinghui; Zhao, Jianlong; Zhang, Qiqing; Mao, Hongju

    2016-12-01

    Carcinoembryonic antigen (CEA) is an important biomarker in cancer diagnosis. Here, we present an efficient, selective lateral-flow immunoassay (LFIA) based on magnetic nanoparticles (MNPs) for in situ sensitive and accurate point-of-care detection of CEA. Signal amplification mechanism involved linking of detection MNPs with signal MNPs through biotin-modified single-stranded DNA (ssDNA) and streptavidin. To verify the effectiveness of this modified LFIA system, the sensitivity and specificity were evaluated. Sensitivity evaluation showed a broad detection range of 0.25-1000ng/ml for CEA protein by the modified LFIA, and the limit of detection (LOD) of the modified LFIA was 0.25ng/ml, thus producing significant increase in detection threshold compared with the traditional LFIA. The modified LFIA could selectively recognize CEA in presence of several interfering proteins. In addition, this newly developed assay was applied for quantitative detection of CEA in human serum specimens collected from 10 randomly selected patients. The modified LFIA system detected minimum 0.27ng/ml of CEA concentration in serum samples. The results were consistent with the clinical data obtained using commercial electrochemiluminescence immunoassay (ECLIA) (pdetected CEA with higher sensitivity and selectivity, and thus has great potential to be commercially applied as a sensitive tumor marker filtration system. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Cascaded fiber-optic Fabry-Perot interferometers with Vernier effect for highly sensitive measurement of axial strain and magnetic field.

    Science.gov (United States)

    Zhang, Peng; Tang, Ming; Gao, Feng; Zhu, Benpeng; Fu, Songnian; Ouyang, Jun; Shum, Perry Ping; Liu, Deming

    2014-08-11

    We report a highly sensitive fiber-optic sensor based on two cascaded intrinsic fiber Fabry-Perot interferometers (IFFPIs). The cascaded IFFPIs have different free spectral ranges (FSRs) and are formed by a short section of hollow core photonic crystal fiber sandwiched by two single mode fibers. With the superposition of reflective spectrum with different FSRs, the Vernier effect will be generated in the proposed sensor and we found that the strain sensitivity of the proposed sensor can be improved from 1.6 pm/με for a single IFFPI sensor to 47.14 pm/με by employing the Vernier effect. The sensor embed with a metglas ribbon can be also used to measure the magnetic field according to the similar principle. The sensitivity of the magnetic field measurement is achieved to be 71.57 pm/Oe that is significantly larger than the 2.5 pm/Oe for a single IFFPI sensor.

  6. Ultra-sensitive Magnetic Microscopy with an Optically Pumped Magnetometer

    Science.gov (United States)

    Kim, Young Jin; Savukov, Igor

    2016-04-01

    Optically pumped magnetometers (OPMs) based on lasers and alkali-metal vapor cells are currently the most sensitive non-cryogenic magnetic field sensors. Many applications in neuroscience and other fields require high-resolution, high-sensitivity magnetic microscopic measurements. In order to meet this demand we combined a cm-size spin-exchange relaxation-free (SERF) OPM and flux guides (FGs) to realize an ultra-sensitive FG-OPM magnetic microscope. The FGs serve to transmit the target magnetic flux to the OPM thus improving both the resolution and sensitivity to small magnetic objects. We investigated the performance of the FG-OPM device using experimental and numerical methods, and demonstrated that an optimized device can achieve a unique combination of high resolution (80 μm) and high sensitivity (8.1 pT/). In addition, we also performed numerical calculations of the magnetic field distribution in the FGs to estimate the magnetic noise originating from the domain fluctuations in the material of the FGs. We anticipate many applications of the FG-OPM device such as the detection of micro-biological magnetic fields; the detection of magnetic nano-particles; and non-destructive testing. From our theoretical estimate, an FG-OPM could detect the magnetic field of a single neuron, which would be an important milestone in neuroscience.

  7. Sensitive detection of Listeria monocytogenes based on highly efficient enrichment with vancomycin-conjugated brush-like magnetic nano-platforms.

    Science.gov (United States)

    Yang, Xiaoke; Zhou, Xiaoming; Zhu, Minjun; Xing, Da

    2017-05-15

    Pathogens pose a significant threat to public health worldwide. Despite many technological advances in the rapid diagnosis of pathogens, sensitive pathogen detection remains challenging because target pathogenic bacteria usually exist in complex samples at very low concentrations. Here, the construction of multivalent brush-like magnetic nanoprobes and their application for the efficient enriching of pathogens are demonstrated. Brush-like magnetic nanoprobes were constructed by modification with poly-L-lysine (PLL) onto amino-modified magnetic beads, followed by coupling of PEG (amine-PEG5000-COOH) to the amine sites of PLL. Subsequently, vancomycin (Van), a small-molecule antibiotic with affinity to the terminal peptide (D-alanyl-D-alanine) on the cell wall of Gram-positive bacteria, was conjugated to the carboxyl of the PEG. The use of multivalent brush-like magnetic nanoprobes (Van-PEG-PLL-MNPs) results in a high enrichment efficiency (>94%) and satisfactory purity for Listeria monocytogenes (employed as a model) within 20min, even at bacterial concentrations of only 10(2)cfumL(-1). Integrated with the enrichment of the Van-PEG-PLL-MNP nano-platform and electrochemiluminescence (ECL) detection, Listeria monocytogenes can be rapidly and accurately detected at levels as low as 10cfumL(-1). The approach described herein holds great potential for realizing rapid and sensitive pathogen detection in clinical samples. Copyright © 2016. Published by Elsevier B.V.

  8. Highly sensitive electrochemical detection of genomic DNA based on stem loop probes structured for magnetic collection and measurement via metalised hollow polyelectrolyte shells.

    Science.gov (United States)

    Khunrattanaporn, Naphat; Rijiravanich, Patsamon; Somasundrum, Mithran; Surareungchai, Werasak

    2015-11-15

    We report a highly sensitive method for the electrochemical detection of genomic DNA, based on the employment of two sub-micron oligonucleotide labels - one for magnetic collection and the other for voltammetric detection - and their incorporation onto a stem loop DNA probe. The magnetic label consists of a latex particle of mean diameter 441±6 nm, bearing magnetic Fe3O4 particles and approx. 3.5×10(5) anti-DIG antibodies. The voltammetric label is a hollow polyelectrolyte shell containing approx. 1.0×10(11) Au atoms in the form of well dispersed Au nanoparticles. A DIG tag on one arm of the stem loop enables binding to the magnetic label, while a thiol tag on the other arm enables attachment to the Au nanoparticles. Due to steric hindrance from the two relatively large labels, attachment of both moieties is dependant on target-probe hybridisation straightening the loop. Once attached, sensitive DNA measurement is facilitated by magnetic collection of the DNA into a small volume and by the high quantity of Au atoms available for detection. Using differential pulse anodic stripping voltammetry we calibrated a 30 mer sequence common to 71 strains of Escherichia coli across the concentration range from 0.1 aM to 100 pM with a LOD of 1.8 aM. Three strains of E. coli, BL 21, ATCC8739, O157:H7, when spiked into UHT milk and fermented palm juice, could be detected with LODs of approx. 2-4 CFU mL(-1) in an assay time of approx. 140 min. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. High-Sensitivity Spectrophotometry.

    Science.gov (United States)

    Harris, T. D.

    1982-01-01

    Selected high-sensitivity spectrophotometric methods are examined, and comparisons are made of their relative strengths and weaknesses and the circumstances for which each can best be applied. Methods include long path cells, noise reduction, laser intracavity absorption, thermocouple calorimetry, photoacoustic methods, and thermo-optical methods.…

  10. High sensitive detection method for protein by combining the magnetic separation with cation exchange based signal amplification.

    Science.gov (United States)

    Xu, Jin; Zhang, Qian-Mei; Zhao, Dong-Xu; Liu, Ya-Ru; Chen, Ping; Lu, Gui-Hong; Xie, Hai-Yan

    2017-06-01

    PSA is a member of low abundance proteins and serves as a critical indicator of the development and therapy efficacy for prostate cancer. In this study, a facile and high sensitive method was developed for serum PSA detection by integrating the immunomagnetic separation and cation exchange based signal amplification. On the basis of nanoparticle preparation and immunoprobe construction, PSA in serum was captured, separated by the immunomagnetic probe and then interacted with the quantum dots (QDs) based immunofluorescence probe; Zn2+ inside QDs was replaced by Ag+ within seconds, after which fluorescence signal was amplified by Fluozin-3, the Zn2+ responsive dye. Under optimized conditions, low detection limit (1.56pg/mL), wide linear range (1.56-25ng/mL) and good repeatability (intra-coefficient variation=3.18%) were achieved, which is superior to commercialized ELISA kit. These results demonstrated the potential of our high sensitive method for PSA detection in clinical. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Sensitivity enhancement by chromatographic peak concentration with ultra-high performance liquid chromatography-nuclear magnetic resonance spectroscopy for minor impurity analysis.

    Science.gov (United States)

    Tokunaga, Takashi; Akagi, Ken-Ichi; Okamoto, Masahiko

    2017-07-28

    High performance liquid chromatography can be coupled with nuclear magnetic resonance (NMR) spectroscopy to give a powerful analytical method known as liquid chromatography-nuclear magnetic resonance (LC-NMR) spectroscopy, which can be used to determine the chemical structures of the components of complex mixtures. However, intrinsic limitations in the sensitivity of NMR spectroscopy have restricted the scope of this procedure, and resolving these limitations remains a critical problem for analysis. In this study, we coupled ultra-high performance liquid chromatography (UHPLC) with NMR to give a simple and versatile analytical method with higher sensitivity than conventional LC-NMR. UHPLC separation enabled the concentration of individual peaks to give a volume similar to that of the NMR flow cell, thereby maximizing the sensitivity to the theoretical upper limit. The UHPLC concentration of compound peaks present at typical impurity levels (5.0-13.1 nmol) in a mixture led to at most three-fold increase in the signal-to-noise ratio compared with LC-NMR. Furthermore, we demonstrated the use of UHPLC-NMR for obtaining structural information of a minor impurity in a reaction mixture in actual laboratory-scale development of a synthetic process. Using UHPLC-NMR, the experimental run times for chromatography and NMR were greatly reduced compared with LC-NMR. UHPLC-NMR successfully overcomes the difficulties associated with analyses of minor components in a complex mixture by LC-NMR, which are problematic even when an ultra-high field magnet and cryogenic probe are used. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. A sensitive magnetic field sensor using BPSCCO thick film

    Indian Academy of Sciences (India)

    A highly sensitive magnetic sensor operating at liquid nitrogen temperature and based on BPSCCO screen-printed thick film, is reported. The sensor resistance for an applied magnetic field of 100 × 10–4T(100 gauss) exhibits an increase by 360% of its value in zero field at 77.4 K. The performance of the sensor in presence ...

  13. Highly Sensitive FRET-Based Fluorescence Immunoassay for Detecting of Aflatoxin B1 Using Magnetic/Silica Core-Shell as a Signal Intensifier.

    Science.gov (United States)

    Kalarestaghi, Alireza; Bayat, Mansour; Hashemi, Seyed Jamal; Razavilar, Vadood

    2015-09-01

    Recently, some new nanobiosensors using different nanoparticles or microarray systems for detection of mycotoxins have been designed . However, rapid, sensitive and early detection of aflatoxicosis would be very helpful to distinguish high-risk persons. We report a highly sensitive competitive immunoassay using magnetic/silica core shell as a signal intensifier for the determination of aflatoxin B1 using fluorescence resonance energy transfer (FRET) from Cd/Te quantum dots (antiaflatoxin B1 antibody immobilized on the surface of Cd/Te quantum dots) to Rhodamine 123 (Rho 123-labeled aflatoxin B1 bound to albumin). The specific immune-reaction between the anti-aflatoxin B1 antibody on the QDs and the labeledaflatoxin B1 brings the Rho 123 fluorophore (acting as the acceptor) and the QDs (acting as the donor) in close spatial proximity and causes FRET to occur upon photo-excitation of the QDs. Using magnetic/silica core shell to intensify the obtained signal is the novelty of this study. Cd/Te QDs were synthesized by the simultaneous reduction of cadmium chloride and tellurium in the presence of sodium borohydride under nitrogen atmosphere. Magnetic nanoparticles were synthesized using FeSO4 and FeCl3 (1:2 molar ratio) and ammonia as an oxidizing agent under nitrogen atmosphere. The prepared magnetic nanoparticles shelled by silica using tetraethoxysilane in the presence of ammonia. Nanoparticles synthesis and monodispersity confirmed by TEM. Immobilization of Cd/Te QDs to antibodies and labeling of aflatoxin B1-albumin by Rho 123 were performed by EDC/NHS reaction in reaction mixture buffer, pH 6, at room temperature. By using the magnetic/silica core shell sensitivity of the system changed from 2×10-11 in our previous study to 2×10-12 in this work. The feasibility of the method established by the detection of aflatoxin B1 in spiked human serum. There is a linear relationship between the decreased fluorescence intensity of Rho 123 with increasing concentration of

  14. Double Fano resonances due to interplay of electric and magnetic plasmon modes in planar plasmonic structure with high sensing sensitivity

    National Research Council Canada - National Science Library

    Wang, Junqiao; Fan, Chunzhen; He, Jinna; Ding, Pei; Liang, Erjun; Xue, Qianzhong

    2013-01-01

    ... between a broad bright mode and narrow dark modes. The bright mode is resulted from the nanorod electric dipole resonance while the dark modes originate from the magnetic dipole induced by LC resonances...

  15. Limited magnetic resonance imaging of the lumbar spine has high sensitivity for detection of acute fractures, infection, and malignancy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Benjamin; Fintelmann, Florian J.; Kamath, Ravi S.; Kattapuram, Susan V.; Rosenthal, Daniel I. [Massachusetts General Hospital, Department of Radiology, Boston, MA (United States)

    2016-12-15

    The objective of this study is to determine how a limited protocol MR examination compares to a full conventional MR examination for the detection of non-degenerative pathology such as acute fracture, infection, and malignancy. A sample of 349 non-contrast MR exams was selected retrospectively containing a 3:1:1:1 distribution of negative/degenerative change only, acute fracture, infection, and malignancy. This resulted in an even distribution of pathology and non-pathology. A limited protocol MR exam was simulated by extracting T1-weighted sagittal and T2-weighted fat-saturated (or STIR) sagittal sequences from each exam and submitting them for blinded review by two experienced musculoskeletal radiologists. The exams were evaluated for the presence or absence of non-degenerative pathology. Interpretation of the limited exam was compared to the original report of the full examination. If either reader disagreed with the original report, the case was submitted for an unblinded adjudication process with the participation of a third musculoskeletal radiologist to establish a consensus diagnosis. There were five false negatives for a sensitivity of 96.9 % for the limited protocol MR exam. Infection in the psoas, paraspinal muscles, and sacroiliac joint, as well as acute fractures in transverse processes and sacrum were missed by one or more readers. No cases of malignancy were missed. Overall diagnostic accuracy was 96.0 % (335/349). MR imaging of the lumbar spine limited to sagittal T1-weighted and sagittal T2 fat-saturated (or STIR) sequences has high sensitivity for the detection of acute fracture, infection, or malignancy compared to a conventional MR examination. (orig.)

  16. High-sensitivity nanosensors for biomarker detection.

    Science.gov (United States)

    Swierczewska, Magdalena; Liu, Gang; Lee, Seulki; Chen, Xiaoyuan

    2012-04-07

    High sensitivity nanosensors utilize optical, mechanical, electrical, and magnetic relaxation properties to push detection limits of biomarkers below previously possible concentrations. The unique properties of nanomaterials and nanotechnology are exploited to design biomarker diagnostics. High-sensitivity recognition is achieved by signal and target amplification along with thorough pre-processing of samples. In this tutorial review, we introduce the type of detection signals read by nanosensors to detect extremely small concentrations of biomarkers and provide distinctive examples of high-sensitivity sensors. The use of such high-sensitivity nanosensors can offer earlier detection of disease than currently available to patients and create significant improvements in clinical outcomes.

  17. High-sensitivity nanosensors for biomarker detection†

    Science.gov (United States)

    Swierczewska, Magdalena; Liu, Gang

    2013-01-01

    High sensitivity nanosensors utilize optical, mechanical, electrical, and magnetic relaxation properties to push detection limits of biomarkers below previously possible concentrations. The unique properties of nanomaterials and nanotechnology are exploited to design biomarker diagnostics. High-sensitivity recognition is achieved by signal and target amplification along with thorough pre-processing of samples. In this tutorial review, we introduce the type of detection signals read by nanosensors to detect extremely small concentrations of biomarkers and provide distinctive examples of high-sensitivity sensors. The use of such high-sensitivity nanosensors can offer earlier detection of disease than currently available to patients and create significant improvements in clinical outcomes. PMID:22187721

  18. High-Resolution, Ultra-Sensitive Magnetic Imaging Using an Ensemble of Nitrogen-Vacancy (NV) Centers in Diamond

    Science.gov (United States)

    2013-07-26

    core particles (cross-linked iron oxide (CLIO) dextran -coated particles developed at MGH). The particles with larger core diameters (obtained from...includes components both normal and parallel to the diamond surface (the 100 crystal plane). The MNPs used in Phase I are superparamagnetic iron ...several types of superparamagnetic iron oxide MNPs for labeling target cells. As described in Section 3 above, the magnetic moment of a

  19. High-sensitivity troponin T predicts infarct scar characteristics and adverse left ventricular function by cardiac magnetic resonance imaging early after reperfused acute myocardial infarction.

    Science.gov (United States)

    Nguyen, Tuan L; Phan, Justin A K; Hee, Leia; Moses, Daniel A; Otton, James; Terreblanche, Owen D; Xiong, Jessica; Premawardhana, Upul; Rajaratnam, Rohan; Juergens, Craig P; Dimitri, Hany R; French, John K; Richards, David A B; Thomas, Liza

    2015-10-01

    Late gadolinium enhancement cardiac magnetic resonance imaging (CMRI) is the current standard for evaluation of myocardial infarct scar size and characteristics. Because post-ST-segment elevation myocardial infarction (STEMI) troponin levels correlate with clinical outcomes, we sought to determine the sampling period for high-sensitivity troponin T (hs-TnT) that would best predict CMRI-measured infarct scar characteristics and left ventricular (LV) function. Among 201 patients with first presentation with STEMI who were prospectively recruited, we measured serial hs-TnT levels at admission, peak, 24 hours, 48 hours, and 72 hours after STEMI. Indexed LV volumes, LV ejection fraction (LVEF) and infarct scar characteristics (scar size, scar heterogeneity, myocardial salvage index, and microvascular obstruction) were evaluated by CMRI at a median of 4 days post-STEMI. Peak and serial hs-TnT levels correlated positively with early indexed LV volumes and infarct scar characteristics, and negatively correlated with myocardial salvage index and LVEF. Both 48- and 72-hour hs-TnT levels similarly predicted "large" total infarct scar size (odds ratios [ORs] 3.08 and 3.53, both P scar size (ORs 2.05 and 2.31, both P scar size, poor myocardial salvage, and LVEF. These levels also correlated with scar heterogeneity and microvascular obstruction post-STEMI. Since ascertaining peak levels after STEMI is challenging in routine practice, based on the biphasic kinetics of hs-TnT, a measurement at 48 to 72 hours (during the plateau phase) provides a useful and simple method for early evaluation of LV function and infarct scar characteristics. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Acid-Sensitive Magnetic Nanoparticles as Potential Drug Depots.

    Science.gov (United States)

    Wuang, Shy Chyi; Neoh, Koon Gee; Kang, En-Tang; Leckband, Deborah E; Pack, Daniel W

    2011-06-01

    Superparamagnetic magnetic nanoparticles were successfully functionalized with poly(methacrylic acid) via atom transfer radical polymerization, followed by conjugation to doxorubicin (Dox). Because of pH-sensitive hydrazone linkages, the rate and extent of Dox release from the particles was higher at a lower pH and/or a higher temperature than at physiological conditions. Appropriate changes to the pH and temperature can increase the drug release from the particles. Because of the released drug, the particles were found to be cytotoxic to human breast cancer cells in vitro. Such magnetic nanoparticles, with the potential to retain drug under physiological conditions and release the drug in conditions where the pH is lower or temperature is higher, may be useful in magnetic drug targeting by reducing the side effects of the drug caused to healthy tissues. In addition, they may serve as hyperthermia agents where the high temperatures used in hyperthermia can trigger further drug release.

  1. High temperature superconductor accelerator magnets

    OpenAIRE

    van Nugteren, J.

    2016-01-01

    For future particle accelerators bending dipoles are considered with magnetic fields exceeding 20T. This can only be achieved using high temperature superconductors (HTS). These exhibit different properties from classical low temperature superconductors and still require significant research and development before they can be applied in a practical accelerator magnet. In order to study HTS in detail, a five tesla demonstrator magnet named Feather-M2 is designed and constructed. The magnet is ...

  2. High Temperature Superconductor Accelerator Magnets

    OpenAIRE

    Van Nugteren, Jeroen; ten Kate, Herman; de Rijk, Gijs; Dhalle, Marc

    2016-01-01

    For future particle accelerators bending dipoles are considered with magnetic fields exceeding $20T$. This can only be achieved using high temperature superconductors (HTS). These exhibit different properties from classical low temperature superconductors and still require significant research and development before they can be applied in a practical accelerator magnet. In order to study HTS in detail, a five tesla demonstrator magnet named Feather-M2 is designed and constructed. The magnet ...

  3. High performance soft magnetic materials

    CERN Document Server

    2017-01-01

    This book provides comprehensive coverage of the current state-of-the-art in soft magnetic materials and related applications, with particular focus on amorphous and nanocrystalline magnetic wires and ribbons and sensor applications. Expert chapters cover preparation, processing, tuning of magnetic properties, modeling, and applications. Cost-effective soft magnetic materials are required in a range of industrial sectors, such as magnetic sensors and actuators, microelectronics, cell phones, security, automobiles, medicine, health monitoring, aerospace, informatics, and electrical engineering. This book presents both fundamentals and applications to enable academic and industry researchers to pursue further developments of these key materials. This highly interdisciplinary volume represents essential reading for researchers in materials science, magnetism, electrodynamics, and modeling who are interested in working with soft magnets. Covers magnetic microwires, sensor applications, amorphous and nanocrystalli...

  4. Magnetocaloric effect in temperature-sensitive magnetic fluids

    Indian Academy of Sciences (India)

    The magnetocaloric properties of three different temperature-sensitive magnetic fluids were studied. The pyromagnetic coefficient for all the materials were obtained and it was found that this property depends on physical and magnetic properties like size, magnetization and Curie temperature. A theoretical model was ...

  5. Self-biased 215 MHz magnetoelectric NEMS resonator for ultra-sensitive DC magnetic field detection.

    Science.gov (United States)

    Nan, Tianxiang; Hui, Yu; Rinaldi, Matteo; Sun, Nian X

    2013-01-01

    High sensitivity magnetoelectric sensors with their electromechanical resonance frequencies NEMS) resonator with an electromechanical resonance frequency of 215 MHz based on an AlN/(FeGaB/Al2O3) × 10 magnetoelectric heterostructure for detecting DC magnetic fields. This magnetoelectric NEMS resonator showed a high quality factor of 735, and strong magnetoelectric coupling with a large voltage tunable sensitivity. The admittance of the magnetoelectric NEMS resonator was very sensitive to DC magnetic fields at its electromechanical resonance, which led to a new detection mechanism for ultra-sensitive self-biased RF NEMS magnetoelectric sensor with a low limit of detection of DC magnetic fields of ~300 picoTelsa. The magnetic/piezoelectric heterostructure based RF NEMS magnetoelectric sensor is compact, power efficient and readily integrated with CMOS technology, which represents a new class of ultra-sensitive magnetometers for DC and low frequency AC magnetic fields.

  6. Magnetic hydrogel with high coercivity

    Energy Technology Data Exchange (ETDEWEB)

    Sözeri, H., E-mail: huseyin.sozeri@tubitak.gov.tr [TUBITAK-UME, National Metrology Institute, PO Box 54, 41470 Gebze-Kocaeli (Turkey); Alveroğlu, E. [Department of Physics, Istanbul Technical University, 34469 Maslak-Istanbul (Turkey); Kurtan, U.; Şenel, M.; Baykal, A. [Department of Chemistry, Fatih University, 34500 B. Cekmece-Istanbul, (Turkey)

    2013-08-01

    Highlights: • Polyacrylamide (PAAm) hydrogels containing magnetic BaFe{sub 12}O{sub 19} nanoparticles have been prepared. • Magnetization measurements reveal that hydrogels have hard magnetic properties with high coercivity. • Magnetic nanoparticles makes the gel more homogeneous and do not diffuse out of the gel during water intake. • These gels are useful in applications as wastewater treatment once gels are magnetized before its usage. - Abstract: This study investigates the synthesis and characterization of polyacrylamide (PAAm) hydrogels containing magnetic BaFe{sub 12}O{sub 19} nanoparticles. Structural, electrical, and magnetic characterization of the gels have been performed with X-ray powder diffractometry, scanning electron microscopy, DC conductivity, magnetization and fluorescence spectroscopy techniques. The preparation and characterization of polyacrylamide (PAAm) hydrogels that contain 5 and 10 mg BaFe{sub 12}O{sub 19} (16 and 21 nm diameter) nanoparticles are described herein. It is seen from the fluorescence spectra that, nanoparticles surrounded to pyranine molecules so that some of pyranine molecules could not bound to the polymer strands. Electrical measurements show that presence of nanoparticles make the gel more homogeneous. Magnetization measurements reveal that hydrogels have hard magnetic properties with quite high coercivity of 4.2 kOe, which does not change with swelling. This feature makes these gels useful in applications as wastewater treatment if they are magnetized before use.

  7. High Magnetic Fields in Chemistry

    Science.gov (United States)

    Steiner, U. E.; Gilch, P.

    Recent applications of large ( 1 T - 30 T) magnetic fields in modern chemical research are reviewed. Magnetic field effects of chemical relevance appear on the levels of quantum mechanics, thermodynamics, and oscopic forces. Quantum mechanical magnetic field effects are governed by the Zeeman interaction and are borne out as static and dynamic effects in spectroscopy and in chemical kinetics. Magnetic circular dichroism (MCD) spectroscopy and magnetic fluorescence quenching in the gas phase serve to illustrate the former, while radical pair spin chemistry is representative of the latter. The principles of the radical pair mechanism are outlined and high-field applications are illustrated in some detail for photo-induced electron transfer reactions of some transition metal complexes. Thermodynamic effects concern the magnetization of chemical samples, which is the focus of magnetochemistry or — more modern — molecular magnetism, and the equilibrium of chemical reactions. Representative examples of both aspects are described. Finally, the exploitation of orientational forces caused by the magnetic anisotropy of larger particles (from omolecules to micro-crystals) is exemplified. Crystal growth in a magnetic field may hold a potential for achieving better control of the quality of protein crystals for structural analysis.

  8. High temperature superconductor accelerator magnets

    NARCIS (Netherlands)

    van Nugteren, J.

    2016-01-01

    For future particle accelerators bending dipoles are considered with magnetic fields exceeding 20T. This can only be achieved using high temperature superconductors (HTS). These exhibit different properties from classical low temperature superconductors and still require significant research and

  9. Three-dimensional sensitivity mapping of a handheld magnetic probe for sentinel lymph node biopsy

    Science.gov (United States)

    Kuwahata, Akihiro; Chikaki, Shinichi; Ergin, Aslı; Kaneko, Miki; Kusakabe, Moriaki; Sekino, Masaki

    2017-05-01

    An experimental apparatus for three-dimensional sensitivity mapping of a handheld magnetic probe with a permanent magnet and a Hall sensor was developed. To optimize the shapes and sizes of the magnets, the sensitivity mappings of two types of magnets, column- and cone-type magnets, were evaluated by the experimental apparatus. The longitudinal sensitivities of column and cone types are 8 and 9 mm, respectively, for 5 μL of magnetic nanoparticles. The measured longitudinal sensitivities agree well with the sensitivities calculated by the finite element method. Furthermore, the maximum lateral resolutions of column and cone types are 4.1 and 3.7 mm, respectively. In terms of the directionality, the sensitivities of column and cone types of the angle of 90° with respect to the probe axis fall approximately to 72% and 50% at 6 mm distance from the probe head, indicating that the cone type has high directionality due to its sharp shape. The measurement of sensitivity mapping revealed that the characteristics of the cone-type magnet are superior to that of the column-type magnet for the identification of sentinel lymph nodes.

  10. High sensitivity probe absorption technique for time-of-flight ...

    Indian Academy of Sciences (India)

    Absorption imaging using a high sensitivity CCD camera gives the size of the expanding cloud and hence ... (LVIS) [2], the peak signal in a 1 mm thick resonant probe beam corresponds to the absorption by 3 × 105 ... used in our atom optics experiments on the reflection of atoms from magnetic thin films [13]. The sensitivity ...

  11. LHC II system sensitivity to magnetic fluids

    CERN Document Server

    Cotae, Vlad

    2005-01-01

    Experiments have been designed to reveal the influences of ferrofluid treatment and static magnetic field exposure on the photosynthetic system II, where the light harvesting complex (LHC II) controls the ratio chlorophyll a/ chlorophyll b (revealing, indirectly, the photosynthesis rate). Spectrophotometric measurement of chlorophyll content revealed different influences for relatively low ferrofluid concentrations (10-30 mul/l) in comparison to higher concentrations (70-100 mul/l). The overlapped effect of the static magnetic field shaped better the stimulatory ferrofluid action on LHC II system in young poppy plantlets.

  12. Strain sensors for high field pulse magnets

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Christian [Los Alamos National Laboratory; Zheng, Yan [Los Alamos National Laboratory; Easton, Daniel [Los Alamos National Laboratory; Farinholt, Kevin M [Los Alamos National Laboratory; Park, Gyuhae [Los Alamos National Laboratory

    2009-01-01

    In this paper we present an investigation into several strain sensing technologies that are being considered to monitor mechanical deformation within the steel reinforcement shells used in high field pulsed magnets. Such systems generally operate at cryogenic temperatures to mitigate heating issues that are inherent in the coils of nondestructive, high field pulsed magnets. The objective of this preliminary study is to characterize the performance of various strain sensing technologies at liquid nitrogen temperatures (-196 C). Four sensor types are considered in this investigation: fiber Bragg gratings (FBG), resistive foil strain gauges (RFSG), piezoelectric polymers (PVDF), and piezoceramics (PZT). Three operational conditions are considered for each sensor: bond integrity, sensitivity as a function of temperature, and thermal cycling effects. Several experiments were conducted as part of this study, investigating adhesion with various substrate materials (stainless steel, aluminum, and carbon fiber), sensitivity to static (FBG and RFSG) and dynamic (RFSG, PVDF and PZT) load conditions, and sensor diagnostics using PZT sensors. This work has been conducted in collaboration with the National High Magnetic Field Laboratory (NHMFL), and the results of this study will be used to identify the set of sensing technologies that would be best suited for integration within high field pulsed magnets at the NHMFL facility.

  13. High Temperature Superconductor Accelerator Magnets

    CERN Document Server

    AUTHOR|(CDS)2079328; de Rijk, Gijs; Dhalle, Marc

    2016-11-10

    For future particle accelerators bending dipoles are considered with magnetic fields exceeding $20T$. This can only be achieved using high temperature superconductors (HTS). These exhibit different properties from classical low temperature superconductors and still require significant research and development before they can be applied in a practical accelerator magnet. In order to study HTS in detail, a five tesla demonstrator magnet named Feather-M2 is designed and constructed. The magnet is based on ReBCO coated conductor, which is assembled into a $10kA$ class Roebel cable. A new and optimized Aligned Block layout is used, which takes advantage of the anisotropy of the conductor. This is achieved by providing local alignment of the Roebel cable in the coil windings with the magnetic field lines. A new Network Model capable of analyzing transient electro-magnetic and thermal phenomena in coated conductor cables and coils is developed. This model is necessary to solve critical issues in coated conductor ac...

  14. Extremely high magnetic-field sensitivity of charge transport in the Mn/SiO2/p-Si hybrid structure

    Directory of Open Access Journals (Sweden)

    N. V. Volkov

    2017-01-01

    Full Text Available We report on abrupt changes in dc resistance and impedance of a diode with the Schottky barrier based on the Mn/SiO2/p-Si structure in a magnetic field. It was observed that at low temperatures the dc and ac resistances of the device change by a factor of more than 106 with an increase in a magnetic field to 200 mT. The strong effect of the magnetic field is observed only above the threshold forward bias across the diode. The ratios between ac and dc magnetoresistances can be tuned from almost zero to 108% by varying the bias. To explain the diversity of magnetotransport phenomena observed in the Mn/SiO2/p-Si structure, it is necessary to attract several mechanisms, which possibly work in different regions of the structure. The anomalously strong magnetotransport effects are attributed to the magnetic-field-dependent impact ionization in the bulk of a Si substrate. At the same time, the conditions for this process are specified by structure composition, which, in turn, affects the current through each structure region. The effect of magnetic field attributed to suppression of impact ionization via two mechanisms leads to an increase in the carrier energy required for initiation of impact ionization. The first mechanism is related to displacement of acceptor levels toward higher energies relative to the top of the valence band and the other mechanism is associated with the Lorentz forces affecting carrier trajectories between scatterings events. The estimated contributions of these two mechanisms are similar. The proposed structure is a good candidate for application in CMOS technology-compatible magnetic- and electric-field sensors and switching devices.

  15. Differential Search Coils Based Magnetometers: Conditioning, Magnetic Sensitivity, Spatial Resolution

    Directory of Open Access Journals (Sweden)

    Timofeeva Maria

    2012-03-01

    Full Text Available A theoretical and experimental comparison of optimized search coils based magnetometers, operating either in the Flux mode or in the classical Lenz-Faraday mode, is presented. The improvements provided by the Flux mode in terms of bandwidth and measuring range of the sensor are detailed. Theory, SPICE model and measurements are in good agreement. The spatial resolution of the sensor is studied which is an important parameter for applications in non destructive evaluation. A general expression of the magnetic sensitivity of search coils sensors is derived. Solutions are proposed to design magnetometers with reduced weight and volume without degrading the magnetic sensitivity. An original differential search coil based magnetometer, made of coupled coils, operating in flux mode and connected to a differential transimpedance amplifier is proposed. It is shown that this structure is better in terms of volume occupancy than magnetometers using two separated coils without any degradation in magnetic sensitivity. Experimental results are in good agreement with calculations.

  16. Oxidative desorption of thiocholine assembled on core-shell Fe3O4/AuNPs magnetic nanocomposites for highly sensitive determination of acetylcholinesterase activity: an exposure biomarker of organophosphates.

    Science.gov (United States)

    Du, Dan; Tao, Yuan; Zhang, Weiying; Liu, Deli; Li, Haibing

    2011-06-15

    Acetylcholinesterase (AChE) activity is a well established biomarker for biomonitoring of exposures to organophosphates (OPs) pesticides and chemical nerve agents. In this work, we described a novel electrochemical oxidative desorption-process of thiocholine, the product of enzymatic reaction, for rapid and highly sensitive determination of AChE activity in human serum. This principle is based on self-assembling of produced thiocholine onto core-shell Fe(3)O(4)/Au nanoparticles (Fe(3)O(4)/AuNPs) magnetic nanocomposites and its oxidation at electrode surface. Fe(3)O(4) magnetic core is not only used for magnetic separation from sample solutions, but also carrying more AuNPs due to its large surface-to-volume ratio. The core-shell Fe(3)O(4)/AuNPs nanocomposites were characterized by UV-Vis spectroscopy, field-emission scanning electron microscopy (FE-SEM) and electrochemical measurements. A linear relationship was obtained between the AChE activity and its concentration from 0.05 to 5.0 mU mL(-1) with a detection limit of 0.02 mU mL(-1). The method showed good results for characterization of AChE spiked human serum and detection of OP exposures from 0.05 to 20 nM, with detection limit of 0.02 nM. This new oxidative desorption assay thus provides a sensitive and quantitative tool for biomonitoring of the exposure to OP pesticides and nerve agents. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. A highly sensitive and selective turn-on fluorogenic and colorimetric sensor based on pyrene-functionalized magnetic nanoparticles for Hg2+ detection and cell imaging.

    Science.gov (United States)

    Chen, Ling; Zheng, Baozhan; Guo, Yong; Du, Juan; Xiao, Dan; Bo, Lin

    2013-12-15

    In this paper, a colorimetric and "turn-on" fluorescent sensor (Py-Si-Fe3O4@SiO2 NPs) for Hg(2+) detection was designed with pyrene derivative covalently grafted onto the surface of magnetic core/shell Fe3O4@SiO2 nanoparticles using the silanol hydrolysis approach. The Py-Si-Fe3O4@SiO2 inorganic-organic hybrid material was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray power diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and fluorescence emission. The results of fluorescence spectra showed that the resultant multifunctional nanoparticles exhibited selective turn-on type fluorescence enhancement with Hg(2+). In addition, the presence of magnetic Fe3O4 nanoparticles in the sensor Py-Si-Fe3O4@SiO2 NPs would also facilitate the magnetic separation of Hg(2+)-Py-Si-Fe3O4@SiO2 from the solution. The as-prepared chemosensor was also successfully applied to detect Hg(2+) in environmental water samples and serum sample. Results from confocal laser scanning microscopy experiments demonstrated that this chemosensor was cell permeable and can be used as a fluorescent probe for monitoring Hg(2+) in living cells. © 2013 Elsevier B.V. All rights reserved.

  18. Levitation performance of the magnetized bulk high- Tc superconducting magnet with different trapped fields

    Science.gov (United States)

    Liu, W.; Wang, J. S.; Liao, X. L.; Zheng, S. J.; Ma, G. T.; Zheng, J.; Wang, S. Y.

    2011-03-01

    To a high- Tc superconducting (HTS) maglev system which needs large levitation force density, the magnetized bulk high- Tc superconductor (HTSC) magnet is a good candidate because it can supply additional repulsive or attractive force above a permanent magnet guideway (PMG). Because the induced supercurrent within a magnetized bulk HTSC is the key parameter for the levitation performance, and it is sensitive to the magnetizing process and field, so the magnetized bulk HTSC magnets with different magnetizing processes had various levitation performances, not only the force magnitude, but also its force relaxation characteristics. Furthermore, the distribution and configuration of the induced supercurrent are also important factor to decide the levitation performance, especially the force relaxation characteristics. This article experimentally investigates the influences of different magnetizing processes and trapped fields on the levitation performance of a magnetized bulk HTSC magnet with smaller size than the magnetic inter-pole distance of PMG, and the obtained results are qualitatively analyzed by the Critical State Model. The test results and analyses of this article are useful for the suitable choice and optimal design of magnetized bulk HTSC magnets.

  19. Spatial sensitivity mapping of Hall crosses using patterned magnetic nanostructures

    NARCIS (Netherlands)

    Alexandrou, M.; Nutter, P.W.; Delalande, M.Y.; de Vries, Jeroen; Hill, E.W.; Schedin, F.; Abelmann, Leon; Thomson, T.

    2010-01-01

    Obtaining an accurate profile of the spatial sensitivity of Hall cross structures is crucial if such devices are to be used to analyze the switching behavior of magnetic nanostructures and determine the switching field distribution of bit patterned media. Here, we have used the anomalous Hall effect

  20. Controlled actuation of alternating magnetic field-sensitive tunable hydrogels

    Science.gov (United States)

    Ghosh, Santaneel; Cai, Tong

    2010-10-01

    The feasibility of using tunable magnetic nano-particles embedded in cylindrical hydrogel materials for guided actuation via controlled modulation of oscillating magnetic field and frequency is investigated. Ferromagnetic nano-particles (Fe3O4) encapsulated within a thermo-sensitive polymer network [-poly(N-isopropylacrylamide) (PNIPAM)] were polymerized inside 1.5 mm diameter capillary tubes. Inside alternating magnetic field (25-70 Oe, 150-280 kHz), the polymer monolith quickly bends along the longitudinal axis. The bending behaviour of the polymer monolith was influenced by the following factors: (a) mechanical strength of the monolith, (b) ac field-induced temperature regulation and (c) the surface evaporation. The equilibrium bending angle reached a maximum value of 74° at 30 Oe, 200 kHz, between 15% and 35% relative humidity conditions. In addition, we found that micro-scale monolith (300 µm diameter) exhibited significantly faster actuation response compared with the 1500 µm diameter hydrogel cylinder. Both de-swelling efficiency and volumetric transition temperature were not affected due to the nano-magnet incorporation. As ac magnetic field-induced controlled modulation can directly transform the absorbed energy into bending and shrinkage simultaneously for temperature sensitive polymers, i.e. the absorbed energy is converted into mechanical work, this novel approach may lead to a new category of magnetically responsive polymeric structures for potential applications in the field of smart gel-based devices, such as micro-sensors and actuators, and particularly in biomedical fields.

  1. Sensitive detection of vortex-core resonance using amplitude-modulated magnetic field

    Science.gov (United States)

    Cui, Xiaomin; Hu, Shaojie; Hidegara, Makoto; Yakata, Satoshi; Kimura, Takashi

    2015-12-01

    Understanding and manipulating the dynamic properties of the magnetic vortices stabilized in patterned ferromagnetic structures are of great interest owing to the superior resonant features with the high thermal stability and their flexible tunability. So far, numerous methods for investigating the dynamic properties of the magnetic vortex have been proposed and demonstrated. However, those techniques have some regulations such as spatial resolution, experimental facility and sensitivity. Here, we develop a simple and sensitive method for investigating the vortex-core dynamics by using the electrically separated excitation and detection circuits. We demonstrate that the resonant oscillation of the magnetic vortex induced by the amplitude- modulated alternating-sign magnetic field is efficiently picked up by the lock-in detection with the modulated frequency. By extending this method, we also investigate the size dependence and the influence of the magneto-static interaction in the resonant property of the magnetic vortex.

  2. Ultra-sensitive NEMS magnetoelectric sensor for picotesla DC magnetic field detection

    Science.gov (United States)

    Li, Menghui; Matyushov, Alexei; Dong, Cunzheng; Chen, Huaihao; Lin, Hwaider; Nan, Tianxiang; Qian, Zhenyun; Rinaldi, Matteo; Lin, Yuanhua; Sun, Nian X.

    2017-04-01

    We report a highly sensitive NEMS DC/low frequency magnetic field sensor consisting of an AlN/FeGaB resonator, with a ΔE effect-based sensing principle. Unlike previously reported magnetic field detection schemes, such as observing induced magnetoelectric voltage, or monitoring impedance, we designed a system to directly measure the reflected output voltage from the sensor as a function of magnetic field. The AlN/FeGaB resonator shows a resonance frequency shift of 3.19 MHz (1.44%), which leads to a high DC magnetic field sensitivity of 2.8 Hz/nT and a limit of detection of 800pT in an unshielded, room temperature and pressure, lab environment.

  3. High-frequency magnetic components

    CERN Document Server

    Kazimierczuk, Marian K

    2013-01-01

    A unique text on the theory and design fundaments of inductors and transformers, updated with more coverage on the optimization of magnetic devices and many new design examples The first edition is popular among a very broad audience of readers in different areas of engineering and science. This book covers the theory and design techniques of the major types of high-frequency power inductors and transformers for a variety of applications, including switching-mode power supplies (SMPS) and resonant dc-to-ac power inverters and dc-to-dc power converters. It describes eddy-current phenomena (su

  4. Acid-Sensitive Magnetic Nanoparticles as Potential Drug Depots

    OpenAIRE

    Wuang, Shy Chyi; Neoh, Koon Gee; Kang, En-Tang; Deborah E. Leckband; Pack, Daniel W.

    2011-01-01

    Superparamagnetic magnetic nanoparticles were successfully functionalized with poly(methacrylic acid) via atom transfer radical polymerization, followed by conjugation to doxorubicin (Dox). Because of pH-sensitive hydrazone linkages, the rate and extent of Dox release from the particles was higher at a lower pH and/or a higher temperature than at physiological conditions. Appropriate changes to the pH and temperature can increase the drug release from the particles. Because of the released dr...

  5. Controlled actuation of alternating magnetic field-sensitive tunable hydrogels

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Santaneel [Department of Physics and Engineering Physics, Southeast Missouri State University, Cape Girardeau, MO 63701 (United States); Cai Tong, E-mail: sghosh@semo.ed [Department of Physics, University of North Texas, Denton, TX 76203 (United States)

    2010-10-20

    The feasibility of using tunable magnetic nano-particles embedded in cylindrical hydrogel materials for guided actuation via controlled modulation of oscillating magnetic field and frequency is investigated. Ferromagnetic nano-particles (Fe{sub 3}O{sub 4}) encapsulated within a thermo-sensitive polymer network [-poly(N-isopropylacrylamide) (PNIPAM)] were polymerized inside 1.5 mm diameter capillary tubes. Inside alternating magnetic field (25-70 Oe, 150-280 kHz), the polymer monolith quickly bends along the longitudinal axis. The bending behaviour of the polymer monolith was influenced by the following factors: (a) mechanical strength of the monolith, (b) ac field-induced temperature regulation and (c) the surface evaporation. The equilibrium bending angle reached a maximum value of 74{sup 0} at 30 Oe, 200 kHz, between 15% and 35% relative humidity conditions. In addition, we found that micro-scale monolith (300 {mu}m diameter) exhibited significantly faster actuation response compared with the 1500 {mu}m diameter hydrogel cylinder. Both de-swelling efficiency and volumetric transition temperature were not affected due to the nano-magnet incorporation. As ac magnetic field-induced controlled modulation can directly transform the absorbed energy into bending and shrinkage simultaneously for temperature sensitive polymers, i.e. the absorbed energy is converted into mechanical work, this novel approach may lead to a new category of magnetically responsive polymeric structures for potential applications in the field of smart gel-based devices, such as micro-sensors and actuators, and particularly in biomedical fields.

  6. Multi-scale magnetic nanoparticle based optomagnetic bioassay for sensitive DNA and bacteria detection

    DEFF Research Database (Denmark)

    Tian, Bo; Zardán Gómez De La Torre, Teresa; Donolato, Marco

    2016-01-01

    Benefiting from their rapid readout, highly flexible devices and low-cost portable systems, optomagnetic biosensors have drawn increased attention in recent years as bioassay technologies for small molecules, biomarkers, DNA, and bacteria. Herein, an optomagnetic bioassay strategy suitable...... for point-of-care diagnostics, utilizing functionalized magnetic nanoparticles (100 nm) with Brownian relaxation behavior is optimized in order to obtain higher detection sensitivity for DNA molecules and bacteria. Presence of target DNA sequences or bacteria changes the dynamic behavior of the magnetic...... to previous work, we systematically optimize the concentration of 100 nm magnetic nanoparticles to increase the assay sensitivity and lower the limit of detection. To enable biplex detection, we perform this optimization in the presence of larger 250 nm magnetic nanoparticles that do not interact...

  7. B1 -sensitivity analysis of quantitative magnetization transfer imaging.

    Science.gov (United States)

    Boudreau, Mathieu; Stikov, Nikola; Pike, G Bruce

    2017-03-27

    To evaluate the sensitivity of quantitative magnetization transfer (qMT) fitted parameters to B1 inaccuracies, focusing on the difference between two categories of T1 mapping techniques: B1 -independent and B1 -dependent. The B1 -sensitivity of qMT was investigated and compared using two T1 measurement methods: inversion recovery (IR) (B1 -independent) and variable flip angle (VFA), B1 -dependent). The study was separated into four stages: 1) numerical simulations, 2) sensitivity analysis of the Z-spectra, 3) healthy subjects at 3T, and 4) comparison using three different B1 imaging techniques. For typical B1 variations in the brain at 3T (±30%), the simulations resulted in errors of the pool-size ratio (F) ranging from -3% to 7% for VFA, and -40% to > 100% for IR, agreeing with the Z-spectra sensitivity analysis. In healthy subjects, pooled whole-brain Pearson correlation coefficients for F (comparing measured double angle and nominal flip angle B1 maps) were ρ = 0.97/0.81 for VFA/IR. This work describes the B1 -sensitivity characteristics of qMT, demonstrating that it varies substantially on the B1 -dependency of the T1 mapping method. Particularly, the pool-size ratio is more robust against B1 inaccuracies if VFA T1 mapping is used, so much so that B1 mapping could be omitted without substantially biasing F. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  8. Improved magnetoelectric effect in magnetostrictive/piezoelectric composite with flux concentration effect for sensitive magnetic sensor

    Directory of Open Access Journals (Sweden)

    Hao Zhang

    2015-04-01

    Full Text Available The magnetoelectric (ME composite with the flux concentration effect is designed, fabricated, and characterized for detecting weak ac magnetic-field. The high-permeability Fe73.5Cu1Nb3Si13.5B9 (FeCuNbSiB foils act as flux concentrators and are bonded at the free ends of traditional ME laminates. With the improved ME responses in the proposed ME composite based on the flux concentration effect, the output sensitivities under zero-biased magnetic field can reach 7 V/Oe and 15.8 mV/Oe under the resonance frequency of 177.36 kHz and the off-resonance frequency of 1 kHz, respectively. The results indicate that the proposed ME composites show promising applications for high-sensitivity self-biased magnetic field sensors and ME transducers.

  9. Radiofrequency solutions in clinical high field magnetic resonance

    NARCIS (Netherlands)

    Andreychenko, A.|info:eu-repo/dai/nl/341697672

    2013-01-01

    Magnetic resonance imaging (MRI) and spectroscopy (MRS) benefit from the sensitivity gain at high field (≥7T). However, high field brings also certain challenges associated with growing frequency and spectral dispersion. Frequency growth results in degraded performance of large volume radiofrequency

  10. High sensory-processing sensitivity at work

    NARCIS (Netherlands)

    Evers, A.; Rasche, J.; Schabracq, M.J.

    2008-01-01

    In this study, the construct validity of an instrument for the measurement of sensory-processing sensitivity (SPS), the Highly Sensitive Person Scale (HSPS), was examined. Among the outcomes, first, the results confirm an earlier conclusion of researchers that the HSPS does not measure a

  11. Aluminum nanocantilevers for high sensitivity mass sensors

    DEFF Research Database (Denmark)

    Davis, Zachary James; Boisen, Anja

    2005-01-01

    We have fabricated Al nanocantilevers using a simple, one mask contact UV lithography technique with lateral and vertical dimensions under 500 and 100 nm, respectively. These devices are demonstrated as highly sensitive mass sensors by measuring their dynamic properties. Furthermore, it is shown...... that Al has a potential higher sensitivity than Si based dynamic sensors. Initial testing of these devices has been conducted using a scanning electron microscope setup were the devices were tested under high vacuum conditions. The Q factor was measured to be approximately 200 and the mass sensitivity...

  12. Magnetic mesoporous thiourea-formaldehyde resin as selective adsorbent: A simple and highly-sensitive electroanalysis strategy for lead ions in drinking water and milk by solid state-based anodic stripping.

    Science.gov (United States)

    Zhao, Yanfang; Xu, Lubin; Liu, Min; Duan, Zhiqiang; Wang, Hua

    2018-01-15

    A simple and sensitive electroanalysis method has been developed for the direct determination of lead ions of nanomolar levels in real samples of drinking water and milk by employing magnetic mesoporous thiourea-formaldehyde resin (TUF@Fe 3 O 4 ) nanocomposites as the capturing absorbents. Here, the prepared TUF@Fe 3 O 4 with the large-surface-area mesoporous structure and strong Pb 2+ -binding ligands could facilitate the selective and large-scale adsorption of Pb 2+ ions from the complex sample matrices to be further magnetically separated onto the magnetic electrodes. Moreover, the Pb 2+ ions magnetically accumulated were electrochemically measured alternatively by the solid state-based anodic stripping of PbCl 2 . The detection limit was found to be 0.0070nmolL -1 . The as-developed Pb 2+ electroanalysis method with the magnetic electrodes and TUF@Fe 3 O 4 nanocomposites could avoid the complicated sample preparation and electrode modification, thus holding the great potential of applications for the Pb 2+ detection in different real samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. [Neurofunctional MRI at high magnetic fields].

    Science.gov (United States)

    Speck, O; Turner, R

    2013-05-01

    Functional magnetic resonance imaging (fMRI) examinations are limited in their sensitivity due to the low activation-induced signal change. Within short tolerable scan times the spatial resolution is thus limited. fMRI is a reliable tool in neuroscience as well as for clinical applications such as presurgical mapping of brain function. The fMRI sensitivity improves greatly (more than linearly) with increasing magnetic field strengths. For many years this was the main driving force in the push towards higher field strengths, such as 7 T. The sensitivity gain is greatest for high spatial resolution and fMRI with very high sub-millimeter resolution becomes feasible. Current results demonstrate that the localization of the blood oxygenation level dependent (BOLD) signal is better than previously assumed. High-field fMRI not only allows quantitative improvements but also opens the way to new information content, such as columnar and layer-dependent functional structures of the cortex. This may pave the way for further information, e.g. the directionality of cortico-cortical connections; however, these possibilities also pose new challenges. New methods for processing such high resolution data are required which do not require spatial smoothing and preserve the high information content. Common spatial resolutions of 2-3 mm are still very well suited for examinations at 3 T where they benefit from the low signal void, lower geometrical distortion and reduced acoustic noise. To achieve higher resolution at 7 T parallel imaging and geometric distortion correction are essential and permit the best congruence with structural data. The echo time at 7 T should be adjusted to about 20-25 ms. Data processing for single subjects or patients should be performed with little or no smoothing to retain resolution. Group studies could achieve good correlation with local normalization. New methods for information extraction, such as multivariate pattern analysis may allow

  14. High magnetic fields science and technology

    CERN Document Server

    Miura, Noboru

    2003-01-01

    This three-volume book provides a comprehensive review of experiments in very strong magnetic fields that can only be generated with very special magnets. The first volume is entirely devoted to the technology of laboratory magnets: permanent, superconducting, high-power water-cooled and hybrid; pulsed magnets, both nondestructive and destructive (megagauss fields). Volumes 2 and 3 contain reviews of the different areas of research where strong magnetic fields are an essential research tool. These volumes deal primarily with solid-state physics; other research areas covered are biological syst

  15. Quench in high temperature superconductor magnets

    CERN Document Server

    Schwartz, J.

    2013-01-01

    High field superconducting magnets using high temperature superconductors are being developed for high energy physics, nuclear magnetic resonance and energy storage applications. Although the conductor technology has progressed to the point where such large magnets can be readily envisioned, quench protection remains a key challenge. It is well-established that quench propagation in HTS magnets is very slow and this brings new challenges that must be addressed. In this paper, these challenges are discussed and potential solutions, driven by new technologies such as optical fiber based sensors and thermally conducting electrical insulators, are reviewed.

  16. Giant spin-torque diode sensitivity in the absence of bias magnetic field

    Science.gov (United States)

    Fang, Bin; Carpentieri, Mario; Hao, Xiaojie; Jiang, Hongwen; Katine, Jordan A.; Krivorotov, Ilya N.; Ocker, Berthold; Langer, Juergen; Wang, Kang L.; Zhang, Baoshun; Azzerboni, Bruno; Amiri, Pedram Khalili; Finocchio, Giovanni; Zeng, Zhongming

    2016-01-01

    Microwave detectors based on the spin-torque diode effect are among the key emerging spintronic devices. By utilizing the spin of electrons in addition to charge, they have the potential to overcome the theoretical performance limits of their semiconductor (Schottky) counterparts. However, so far, practical implementations of spin-diode microwave detectors have been limited by the necessity to apply a magnetic field. Here, we demonstrate nanoscale magnetic tunnel junction microwave detectors, exhibiting high-detection sensitivity of 75,400 mV mW−1 at room temperature without any external bias fields, and for low-input power (micro-Watts or lower). This sensitivity is significantly larger than both state-of-the-art Schottky diode detectors and existing spintronic diodes. Micromagnetic simulations and measurements reveal the essential role of injection locking to achieve this sensitivity performance. This mechanism may provide a pathway to enable further performance improvement of spin-torque diode microwave detectors. PMID:27052973

  17. Highly Efficient Freestyle Magnetic Nanoswimmer.

    Science.gov (United States)

    Li, Tianlong; Li, Jinxing; Morozov, Konstantin I; Wu, Zhiguang; Xu, Tailin; Rozen, Isaac; Leshansky, Alexander M; Li, Longqiu; Wang, Joseph

    2017-08-09

    The unique swimming strategies of natural microorganisms have inspired recent development of magnetic micro/nanorobots powered by artificial helical or flexible flagella. However, as artificial nanoswimmers with unique geometries are being developed, it is critical to explore new potential modes for kinetic optimization. For example, the freestyle stroke is the most efficient of the competitive swimming strokes for humans. Here we report a new type of magnetic nanorobot, a symmetric multilinked two-arm nanoswimmer, capable of efficient "freestyle" swimming at low Reynolds numbers. Excellent agreement between the experimental observations and theoretical predictions indicates that the powerful "freestyle" propulsion of the two-arm nanorobot is attributed to synchronized oscillatory deformations of the nanorobot under the combined action of magnetic field and viscous forces. It is demonstrated for the first time that the nonplanar propulsion gait due to the cooperative "freestyle" stroke of the two magnetic arms can be powered by a plane oscillatory magnetic field. These two-arm nanorobots are capable of a powerful propulsion up to 12 body lengths per second, along with on-demand speed regulation and remote navigation. Furthermore, the nonplanar propulsion gait powered by the consecutive swinging of the achiral magnetic arms is more efficient than that of common chiral nanohelical swimmers. This new swimming mechanism and its attractive performance opens new possibilities in designing remotely actuated nanorobots for biomedical operation at the nanoscale.

  18. Synchrotron Applications of High Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    This workshop aims at discussing the scientific potential of X-ray diffraction and spectroscopy in magnetic fields above 30 T. Pulsed magnetic fields in the range of 30 to 40 T have recently become available at Spring-8 and the ESRF (European synchrotron radiation facility). This document gathers the transparencies of the 6 following presentations: 1) pulsed magnetic fields at ESRF: first results; 2) X-ray spectroscopy and diffraction experiments by using mini-coils: applications to valence state transition and frustrated magnet; 3) R{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4}: an ideal system to be studied in X-ray under high magnetic field?; 4) high field studies at the Advanced Photon Source: present status and future plans; 5) synchrotron X-ray diffraction studies under extreme conditions; and 6) projects for pulsed and steady high magnetic fields at the ESRF.

  19. Magnetization of High Density Hadronic Fluid

    DEFF Research Database (Denmark)

    Bohr, Henrik; Providencia, Constanca; da Providencia, João

    2012-01-01

    In the present paper the magnetization of a high density relativistic fluid of elementary particles is studied. At very high densities, such as may be found in the interior of a neutron star, when the external magnetic field is gradually increased, the energy of the normal phase of the fluid...... of the magnetization is derived by first considering and solving the Dirac equation of a fermion in interaction with a magnetic field and with a chiral sigma-pion pair. The solution provides the energies of single-particle states. The energy of the system is found by summing up contributions from all particles...

  20. High Field Pulse Magnets with New Materials

    Science.gov (United States)

    Li, L.; Lesch, B.; Cochran, V. G.; Eyssa, Y.; Tozer, S.; Mielke, C. H.; Rickel, D.; van Sciver, S. W.; Schneider-Muntau, H. J.

    2004-11-01

    High performance pulse magnets using the combination of CuNb conductor and Zylon fiber composite reinforcement with bore sizes of 24, 15 and 10 mm have been designed, manufactured and tested to destruction. The magnets successfully reached the peak fields of 64, 70 and 77.8 T respectively with no destruction. Failures occurred near the end flanges at the layer. The magnet design, manufacturing and testing, and the mode of the failure are described and analyzed.

  1. Sensitivity of a search for cosmic ray sources including magnetic field effects

    Energy Technology Data Exchange (ETDEWEB)

    Urban, Martin; Erdmann, Martin; Mueller, Gero [III. Physikalisches Institut A, RWTH Aachen University (Germany)

    2016-07-01

    We analyze the sensitivity of a new method investigating correlations between ultra-high energy cosmic rays and extragalactic sources taking into account deflections in the galactic magnetic field. In comparisons of expected and simulated arrival directions of cosmic rays we evaluate the directional characteristics and magnitude of the field. We show that our method is capable of detecting anisotropy in data sets with a low signal fraction.

  2. High magnetic field {mu}SR instrument scientific case

    Energy Technology Data Exchange (ETDEWEB)

    Amato, A

    2005-10-15

    In order to gain more insight into the specific behavior of materials, it is often necessary to perform measurements as a function of different external parameters. Despite its high sensitivity to internal fields, this simple observation also applies for the {mu}SR technique. The most common parameter which can be tuned during an experiment is the sample temperature. By using a range of cryostats, temperatures between 0.02 and 900 K can be covered at the PSI {mu}SR Facility. On the other hand, and by using high-energy muons, pressures as high as 10'000 bars can nowadays be reached during {mu}SR experiments. As will be demonstrated in the following Sections, the magnetic field is an additional external parameter playing a fundamental role when studying the ground state properties of materials in condensed matter physics and chemistry. However, the availability of high magnetic fields for {mu}SR experiments is still rather limited. Hence, if on one hand the high value of the gyromagnetic ratio of the muon provides the high magnetic sensitivity of the method, on the other hand it can lead to very high muon-spin precession frequencies when performing measurements in applied fields (the muon-spin precession frequency in a field of 1 Tesla s 135.5 MHz). Consequently, the use of ultra-fast detectors and electronics is mandatory when measuring in magnetic fields exceeding 1 Tesla. If such fields are very intense when compared to the Earth magnetic field < 10{sup -4} Tesla), the energy associated with them is still modest in view of the thermal energy. Hence, the Zeeman energy splitting of a free electron in a magnetic field of 1 Tesla corresponds to a thermal energy as low as 0.67 Kelvin. It is worth mentioning that nowadays magnetic fields of the order of 10 to 15 Tesla are quite common in condensed matter laboratories and have opened up vast new exciting experimental possibilities. (author)

  3. Sensitive magnetic biodetection using magnetic multi-core nanoparticles and RCA coils

    Energy Technology Data Exchange (ETDEWEB)

    Ahrentorp, Fredrik; Blomgren, Jakob; Jonasson, Christian; Sarwe, Anna [Acreo Swedish ICT AB, Arvid Hedvalls Backe 4, Göteborg (Sweden); Sepehri, Sobhan; Eriksson, Emil; Kalaboukhov, Alexei; Jesorka, Aldo; Winkler, Dag [Department of Microtechnology and Nanoscience – MC2, Chalmers University of Technology, Göteborg (Sweden); Schneiderman, Justin F. [Institute of Neuroscience and Physiology, University of Gothenburg and MedTech West, Göteborg (Sweden); Nilsson, Mats [Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Stockholm (Sweden); Albert, Jan [Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm (Sweden); Department of Clinical Microbiology, Karolinska University Hospital, Stockholm (Sweden); Zardán Gómez de la Torre, Teresa; Strømme, Maria [Uppsala University, Uppsala (Sweden); Johansson, Christer, E-mail: christer.johansson@acreo.se [Acreo Swedish ICT AB, Arvid Hedvalls Backe 4, Göteborg (Sweden)

    2017-04-01

    We use functionalized iron oxide magnetic multi-core particles of 100 nm in size (hydrodynamic particle diameter) and AC susceptometry (ACS) methods to measure the binding reactions between the magnetic nanoparticles (MNPs) and bio-analyte products produced from DNA segments using the rolling circle amplification (RCA) method. We use sensitive induction detection techniques in order to measure the ACS response. The DNA is amplified via RCA to generate RCA coils with a specific size that is dependent on the amplification time. After about 75 min of amplification we obtain an average RCA coil diameter of about 1 µm. We determine a theoretical limit of detection (LOD) in the range of 11 attomole (corresponding to an analyte concentration of 55 fM for a sample volume of 200 µL) from the ACS dynamic response after the MNPs have bound to the RCA coils and the measured ACS readout noise. We also discuss further possible improvements of the LOD. - Highlights: • Biosensing using Brownian relaxation of functionalized magnetic nanoparticles. • Rolling circle amplification and magnetic nanoparticles enables biosensing. • Theoretical limit of detection estimated from the signal noise gives about 55 fM.

  4. Sensitivity analysis of magnetic field measurements for magnetic resonance electrical impedance tomography (MREIT)

    DEFF Research Database (Denmark)

    Göksu, Cihan; Scheffler, Klaus; Ehses, Philipp

    2017-01-01

    Purpose: Clinical use of magnetic resonance electrical impedance tomography (MREIT) still requires significant sensitivity improvements. Here, the measurement of the current-induced magnetic field (DBz,c) is improved using systematic efficiency analyses and optimization of multi-echo spin echo...... parameters, are analytically analyzed and simulated. The theoretical results are experimentally validated in a saline-filled homogenous spherical phantom with relaxation parameters similar to brain tissue. Measurement of DBz,c is also performed in a cylindrical phantom with saline and chicken meat. Results......: The efficiency simulations and experimental results are in good agreement. When using optimal parameters, DBz,c can be reliably measured in the phantom even at injected current strengths of 1 mA or lower for both sequence types. The importance of using proper crusher gradient selection on the phase evolution...

  5. Multifunctional magnetic-plasmonic nanoparticles for fast concentration and sensitive detection of bacteria using SERS.

    Science.gov (United States)

    Zhang, Lei; Xu, Jiajie; Mi, Luo; Gong, Heng; Jiang, Shaoyi; Yu, Qiuming

    2012-01-15

    Multifunctional magnetic-plasmonic Fe(3)O(4)-Au core-shell nanoparticles (Au-MNPs) were prepared for simultaneous fast concentration of bacterial cells by applying an external point magnetic field, and sensitive detection and identification of bacteria using surface-enhanced Raman spectroscopy (SERS). We demonstrated that a spread of a 10 μL drop of a mixture of 10(5) cfu/mL bacteria and 3 μg/mL Au-MNPs on a silicon surface can be effectively condensed into a highly compact dot within 5 min by applying an external point magnetic field, resulting in 60 times more concentrated bacteria in the dot area than on the spread area without concentration. Surrounded by dense uniformly packed Au-MNPs, bacteria can be sensitively and reproducibly detected directly using SERS. The principle component analysis (PCA) showed that three different Gram-negative bacterial strains can be clearly differentiated. We also demonstrated that the condensed multifunctional Au-MNPs dot can be used as a highly sensitive SERS-active substrate and a limit of detection better than 0.1 ppb was obtained in detection of small molecules such as 4-mercaptopyrine. This novel platform significantly simplifies the concentration and detection process, which holds great promise for applications in food safety, environmental monitoring, medical diagnoses, and chemical and biological threat detections. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Highly strain-sensitive magnetostrictive tunnel magnetoresistance junctions

    Science.gov (United States)

    Tavassolizadeh, Ali; Hayes, Patrick; Rott, Karsten; Reiss, Günter; Quandt, Eckhard; Meyners, Dirk

    2015-06-01

    Tunnel magnetoresistance (TMR) junctions with CoFeB/MgO/CoFeB layers are promising for strain sensing applications due to their high TMR effect and magnetostrictive sense layer (CoFeB). TMR junctions available even in submicron dimensions can serve as strain sensors for microelectromechanical systems devices. Upon stress application, the magnetization configuration of such junctions changes due to the inverse magnetostriction effect resulting in strain-sensitive tunnel resistance. Here, strain sensitivity of round-shaped junctions with diameters of 11.3 μm, 19.2 μm, 30.5 μm, and 41.8 μm were investigated on macroscopic cantilevers using a four-point bending apparatus. This investigation mainly focuses on changes in hard-axis TMR loops caused by the stress-induced anisotropy. A macrospin model is proposed, supported by micromagnetic simulations, which describes the complete rotation of the sense layer magnetization within TMR loops of junctions, exposed to high stress. Below 0.2‰ tensile strain, a representative junction with 30.5 μm diameter exhibits a very large gauge factor of 2150. For such high gauge factor a bias field H = - 3.2 kA / m is applied in an angle equal to 3 π / 2 toward the pinned magnetization of the reference layer. The strain sensitivity strongly depends on the bias field. Applying stress along π / 4 against the induced magnetocrystalline anisotropy, both compressive and tensile strain can be identified by a unique sensor. More importantly, a configuration with a gauge factor of 400 at zero bias field is developed which results in a straightforward and compact measuring setup.

  7. Alignment of Carbon Nanotubes Comprising Magnetically Sensitive Metal Oxides in Nanofluids

    Science.gov (United States)

    Hong, Haiping (Inventor); Peterson, G. P. " Bud" (Inventor)

    2016-01-01

    The present invention is a nanoparticle mixture or suspension or nanofluid comprising nonmagnetically sensitive nanoparticles, magnetically sensitive nanoparticles, and surfactant(s). The present invention also relates to methods of preparing and using the same.

  8. High magnetic field magnetization of a new triangular lattice antiferromagnet

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, H. D. [Univ. of Tennessee, Knoxville, TN (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States). National High Magnetic Field Lab. (MagLab); Stritzinger, Laurel Elaine Winter [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Harrison, Neil [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-03-23

    In CsV(MoO4)2, the magnetic V3+ ions with octahedral oxygen-coordination form a geometrically frustrated triangular lattice. So fare, there is no magnetic properties reported on it. Recently, we successfully grew single crystals of CsV(MoO4)2 by using flux method. The susceptibility shows a sharp drop around 24 K, representing a long range magnetic ordering. To understand the physical properties of this new triangular lattice antiferromagnet (TLAF), we pursued high field magnetization measurements to answer two questions: (i) what is the saturation field, which will be very useful to calculate the exchange interaction of the system? (ii) Will it exhibit spin state transition, such as the up up down phase with 1/3-saturation moment as other TLAFs? Recently, we performed VSM measurements in Cell 8, Tallahassee, NHMFL, the results show that the magnetization reaches 0.38 MuB at 34 T, which is just 19% of the full moment of 2 MuB for V3+ (3d2) ions. Apparently we need higher field to reach 1/3 value or full moment.

  9. Superconductivity from magnetic elements under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Katsuya [KYOKUGEN, Research Center for Materials Science at Extreme Conditions, Osaka University, Osaka 560-8531 (Japan)]. E-mail: shimizu@rcem.osaka-u.ac.jp; Amaya, Kiichi [Toyota Physical and Chemical Research Institute, Aichi 480-1192 (Japan); Suzuki, Naoshi [Graduate School of Engineering Science, Osaka University, Osaka 560-8531 (Japan); Onuki, Yoshichika [Graduate School of Science, Osaka University, Osaka 560-0043 (Japan)

    2006-05-01

    Can we expect the appearance of superconductivity from magnetic elements? In general, superconductivity occurs in nonmagnetic metal at low temperature and magnetic impurities destroy superconductivity; magnetism and superconductivity are as incompatible as oil and water. Here, we present our experimental example of superconducting elements, iron and oxygen. They are magnetic at ambient pressure, however, they become nonmagnetic under high pressure, then superconductor at low temperature. What is the driving force of the superconductivity? Our understanding in the early stages was a simple scenario that the superconductive state was obtained as a consequence of an emergence of the nonmagnetic states. In both cases, we may consider another scenario for the appearance of superconductivity; the magnetic fluctuation mechanism in the same way as unconventional superconductors.

  10. Magnetic and Superconducting Materials at High Pressures

    Energy Technology Data Exchange (ETDEWEB)

    Struzhkin, Viktor V. [Carnegie Inst. of Washington, Washington, DC (United States)

    2015-03-24

    The work concentrates on few important tasks in enabling techniques for search of superconducting compressed hydrogen compounds and pure hydrogen, investigation of mechanisms of high-Tc superconductivity, and exploring new superconducting materials. Along that route we performed several challenging tasks, including discovery of new forms of polyhydrides of alkali metal Na at very high pressures. These experiments help us to establish the experimental environment that will provide important information on the high-pressure properties of hydrogen-rich compounds. Our recent progress in RIXS measurements opens a whole field of strongly correlated 3d materials. We have developed a systematic approach to measure major electronic parameters, like Hubbard energy U, and charge transfer energy Δ, as function of pressure. This technique will enable also RIXS studies of magnetic excitations in iridates and other 5d materials at the L edge, which attract a lot of interest recently. We have developed new magnetic sensing technique based on optically detected magnetic resonance from NV centers in diamond. The technique can be applied to study superconductivity in high-TC materials, to search for magnetic transitions in strongly correlated and itinerant magnetic materials under pressure. Summary of Project Activities; development of high-pressure experimentation platform for exploration of new potential superconductors, metal polyhydrides (including newly discovered alkali metal polyhydrides), and already known superconductors at the limit of static high-pressure techniques; investigation of special classes of superconducting compounds (high-Tc superconductors, new superconducting materials), that may provide new fundamental knowledge and may prove important for application as high-temperature/high-critical parameter superconductors; investigation of the pressure dependence of superconductivity and magnetic/phase transformations in 3d transition metal compounds, including

  11. Wuhan pulsed high magnetic field center

    OpenAIRE

    Li, Liang; Peng, Tao; Ding, Honfa; Han, Xiaotao; Ding, Tonghai; Chen, Jin; Wang, Junfeng; Xie, Jianfeng; Wang, Shaoliang; Duan, Xianzhong; Wang, Cheng; Herlach, Fritz; Vanacken, Johan; Pan, Yuan

    2008-01-01

    Wuhan pulsed high magnetic field facility is under development. Magnets of bore sizes from 12 to 34 mm with the peak field in the range of 50 to 80 T have been designed. The pulsed power supplies consists of a 12 MJ, 25 kV capacitor bank and a 100 MVA/100 MJ flywheel pulse generator. A prototype 1 MJ, 25 kV capacitor bank is under construction. Five magnets wound with CuNb wire and copper wire reinforced internally with Zylon fiber composites and externally with stainless steel shells have be...

  12. Magnetocaloric effect in temperature-sensitive magnetic fluids

    Indian Academy of Sciences (India)

    Unknown

    The pyromagnetic coefficient for all the materials were obtained and it was found that this property depends on physical and magnetic ... Magnetic fluid; pyromagnetic coefficient; Curie temperature. 1. Introduction. A magnetic fluid .... fluid, the distribution of particle size generally follows the log-normal distribution function ...

  13. Novel High Temperature Magnetic Bearings for Space Vehicle Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Previous high temperature magnetic bearings employed only electromagnets. The work proposed in this SBIR program seeks to utilize High Temperature Permanent Magnets...

  14. Novel High Temperature Magnetic Bearings for Space Vehicle Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Previous high temperature magnetic bearings employed electromagnets only. The work proposed in this SBIR program seeks to utilize High Temperature Permanent Magnets...

  15. Neutron Scattering and High Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    Winn, Barry L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Stone, Matthew B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-11-01

    The workshop “Neutron Scattering and High Magnetic Fields” was held September 4-5, 2014 at the Oak Ridge National Laboratory (ORNL). The workshop was held in response to a recent report by the National Research Council of the National Academy of Sciences entitled “High Magnetic Field Science and Its Application in the United States: Current Status and Future Directions.”1 This report highlights the fact that neutron scattering measurements carried out in high magnetic fields provide important opportunities for new science. The workshop explored the range of the scientific discoveries that could be enabled with neutron scattering measurements at high fields (25 Tesla or larger), the various technologies that might be utilized to build specialized instruments and sample environment equipment to enable this research at ORNL, and possible routes to funding and constructing these facilities and portable high field sample environments.

  16. High-frequency behavior of magnetic composites

    Science.gov (United States)

    Lagarkov, Andrey N.; Rozanov, Konstantin N.

    2009-07-01

    The paper reviews recent progress in the field of microwave magnetic properties of composites. The problem under discussion is developing composites with high microwave permeability that are needed in many applications. The theory of magnetic composites is briefly sketched with the attention paid to the laws governing the magnetic frequency dispersion in magnetic materials and basic mixing rules for composites. Recent experimental reports on the microwave performance of magnetic composites, as well as data on the agreement of the mixing rules with the measured permeability of composites that are available from the literature are discussed. From the data, a conclusion is made that the validity of a mixing rule is determined by the permeability contrast in the composite, i.e., the difference between permeability of inclusions and that of the host matrix. When the contrast is low, the Maxwell Garnet mixing rule is frequently valid. When the contrast is high, which is of the most interest for obtaining high microwave permeability of a composite, no conventionally accepted theory is capable of accurately predicting the permeability of the composites. Therefore, the mixing rules do not allow the microwave properties of magnetic composites to be predicted when the permeability of inclusions is high, that is the case of the most interest. Because of that, general limitations to the microwave performance of composites are of importance. In particular, an important relation constraining the microwave permeability of composites follows from Kittel's theory of ferromagnetic resonance and analytical properties of frequency dependence of permeability. Another constraint concerning the bandwidth of electromagnetic wave absorbers follows from the Kramers-Kronig relations for the reflection coefficient. The constraints are of importance in design and analysis of electromagnetic wave absorbers and other devices that employ the microwave magnetic properties of composites, such as

  17. Iron oxide nanoparticle-micelles (ION-micelles) for sensitive (molecular) magnetic particle imaging and magnetic resonance imaging

    NARCIS (Netherlands)

    Starmans, Lucas W. E.; Burdinski, Dirk; Haex, Nicole P. M.; Moonen, Rik P. M.; Strijkers, Gustav J.; Nicolay, Klaas; Grüll, Holger

    2013-01-01

    Iron oxide nanoparticles (IONs) are a promising nanoplatform for contrast-enhanced MRI. Recently, magnetic particle imaging (MPI) was introduced as a new imaging modality, which is able to directly visualize magnetic particles and could serve as a more sensitive and quantitative alternative to MRI.

  18. Cooled membrane for high sensitivity gas sampling.

    Science.gov (United States)

    Jiang, Ruifen; Pawliszyn, Janusz

    2014-04-18

    A novel sample preparation method that combines the advantages of high surface area geometry and cold surface effect was proposed to achieve high sensitivity gas sampling. To accomplish this goal, a device that enables the membrane to be cooled down was developed for sampling, and a gas chromatograph-mass spectrometer was used for separation and quantification analysis. Method development included investigation of the effect of membrane temperature, membrane size, gas flow rate and humidity. Results showed that high sensitivity for equilibrium sampling, such as limonene sampling in the current study could be achieved by either cooling down the membrane and/or using a large volume extraction phase. On the other hand, for pre-equilibrium extraction, in which the extracted amount was mainly determined by membrane surface area and diffusion coefficient, high sensitivity could be obtained by using thinner membranes with a larger surface and/or a higher sampling flow rate. In addition, humidity showed no significant influence on extraction efficiency, due to the absorption property of the liquid extraction phase. Next, the limit of detection (LOD) was found, and the reproducibility of the developed cooled membrane gas sampling method was evaluated. Results showed that LODs with a membrane diameter of 19mm at room temperature sampling were 9.2ng/L, 0.12ng/L, 0.10ng/L for limonene, cinnamaldehyde and 2-pentadecanone, respectively. Intra- and inter-membrane sampling reproducibility revealed RSD% lower than 8% and 13%, respectively. Results uniformly demonstrated that the proposed cooled membrane device could serve as an alternative powerful tool for future gas sampling. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Study of High-Efficiency Motors Using Soft Magnetic Cores

    Science.gov (United States)

    Tokoi, Hirooki; Kawamata, Shoichi; Enomoto, Yuji

    We have been developed a small and highly efficient axial gap motor whose stator core is made of a soft magnetic core. First, the loss sensitivities to various motor design parameters were evaluated using magnetic field analysis. It was found that the pole number and core dimensions had low sensitivity (≤ 2.2dB) in terms of the total loss, which is the sum of the copper loss and the iron losses in the stator core and the rotor yoke respectively. From this, we concluded that to improve the motor efficiency, it is essential to reduce the iron loss in the rotor yoke and minimize other losses. With this in mind, a prototype axial gap motor is manufactured and tested. The motor has four poles and six slots. The motor is 123mm in diameter and the axial length is 47mm. The rotor has parallel magnetized magnets and a rotor yoke with magnetic steel sheets. The maximum measured motor efficiency is 93%. This value roughly agrees with the maximum calculated efficiency of 95%.

  20. Review of high-sensitivity Radon studies

    Science.gov (United States)

    Wojcik, M.; Zuzel, G.; Simgen, H.

    2017-10-01

    A challenge in many present cutting-edge particle physics experiments is the stringent requirements in terms of radioactive background. In peculiar, the prevention of Radon, a radioactive noble gas, which occurs from ambient air and it is also released by emanation from the omnipresent progenitor Radium. In this paper we review various high-sensitivity Radon detection techniques and approaches, applied in the experiments looking for rare nuclear processes happening at low energies. They allow to identify, quantitatively measure and finally suppress the numerous sources of Radon in the detectors’ components and plants.

  1. The high sensitivity double beta spectrometer TGV

    Science.gov (United States)

    Briancon, Ch.; Brudanin, V. B.; Egorov, V. G.; Janout, Z.; Koníček, J.; Kovalík, A.; Kovalenko, V. E.; Kubašta, J.; Pospíšil, S.; Revenko, A. V.; Rukhadze, N. I.; Salamatin, A. V.; Sandukovsky, V. G.; Štekl, I.; Timkin, V. V.; Tsupko-Sitnikov, V. V.; Vorobel, V.; Vylov, Ts.

    1996-02-01

    A high sensitivity double beta spectrometer TGV (Telescope Germanium Vertical) has been developed. It is based on 16 HPGe detectors of volume 1200 × 6 mm 3 each in the same cryostat. The TGV spectrometer was proposed for the study of ultrarare nuclear processes (e.g. 2νββ, 0νββ, 2νEC/EC). Details of the TGV spectrometer construction are described, the principles of background suppression, the results of Monte Carlo simulations and the results of test background measurements (in Dubna and Modane underground laboratory) are provided.

  2. [Clinical interpretation of high sensitivity troponin T].

    Science.gov (United States)

    Alquézar Arbé, Aitor; Santaló Bel, Miguel; Sionis, Alessandro

    2015-09-21

    Determination of cardiac troponin (cTn) is necessary for the diagnosis of acute myocardial infarction without ST segment elevation. However Tnc can be released in other clinical situations. The development of high-sensitive cTn T assays (hs-cTnT) improves the management of patients with suspected acute coronary syndrome. Here, we provide an overview of the diverse causes of hs-cTnT elevation and recommend strategies for the clinical interpretation of the test result. Copyright © 2014 Elsevier España, S.L.U. All rights reserved.

  3. Sensitivity of high-resolution three-dimensional magnetic resonance angiography and three-dimensional spoiled-gradient recalled imaging in the prediction of neurovascular compression in patients with hemifacial spasm.

    Science.gov (United States)

    Raslan, Ahmed M; DeJesus, Reynaldo; Berk, Caglar; Zacest, Andrew; Anderson, Jim C; Burchiel, Kim J

    2009-10-01

    Hemifacial spasm is a clinical syndrome caused by vascular compression of the facial nerve in the cerebellopontine angle, which can be relieved by surgical intervention. Advances in medical imaging technology allow for direct visualization of the offending blood vessels in hemifacial spasm and similar conditions (such as trigeminal neuralgia). The utility of high resolution 3D MR angiography and 3D spoiled-gradient recalled (SPGR) imaging sequences for surgical decision-making in hemifacial spasm, as measured by sensitivity, specificity, and positive and negative predictive values, has not been previously determined. A retrospective review was undertaken of 23 patients with hemifacial spasm who underwent operations between January 2001 and December 2006 at Oregon Health & Science University. All patients underwent preoperative high-resolution 3D MR angiography and 3D SPGR imaging. The sensitivity of the SPGR imaging/MR angiography interpretation of neurovascular compression (NVC) by both a neurosurgeon and 2 neuroradiologists was determined in relation to the presence of actual NVC during surgery. All patients were found to have NVC at surgery. After review by a neurosurgeon and 2 neuroradiologists, imaging data from 19 of the 23 patients were evaluated. The neurosurgeon's interpretation had a sensitivity of 79% and a positive predictive value (PPV) of 100%. The first neuroradiologist's interpretation had a sensitivity of 21% with a PPV of 100%. Further interpretation by a blinded second neuroradiologist with expertise in MR imaging of hemifacial spasm and trigeminal neuralgia was conducted, and sensitivity was 59% and PPV was 100%. Specificity was not determined because there were no true negative cases. The negative predictive value was 0% for both the neurosurgeon's and neuroradiologists' evaluations. Although high-resolution 3D MR angiography and 3D SPGR imaging was helpful in providing information about the anatomical relationship of cranial nerve VII and

  4. Sensitivity Analysis and Simulation of Theoretical Response of Ceramics to Strong Magnetic Fields

    Science.gov (United States)

    2016-09-01

    suspensions at relatively low (1.8 T) applied magnetic fields. This corresponds well to preliminary experimental results. Additionally, the sensitivity...of magnetic response to process variables, such as variations in applied magnetic field and suspension viscosity, is assessed. Results indicate that...susceptibilities of the crystallographic planes that are perpendicular and parallel to the magnetic field following alignment respectively, µ0 is the

  5. Pulsing ULXs as highly magnetized neutron stars

    Science.gov (United States)

    Mushtukov, A.; Suleimanov, V.; Tsygankov, S.; Poutanen, J.

    2017-10-01

    A recent discovery of three pulsing ultraluminous X-ray sources (ULXs) demonstrates that a significant part of ULXs could be magnetized neutron stars with extremely high mass accretion rates. Theoreticians are thus faced with a significant challenge to invent a way for transforming a highly super-Eddington accretion rate into pulsing photon luminosity. We suggested a model of the two tall accretion columns above a strongly magnetized (B ˜ 10^{14} G) neutron star surface in the vicinity of the magnetic poles as a source of this radiation, and showed that their luminosity can be as high as 10^{40} erg s^{-1}. We present the basic ideas of the model as well as possible directions for improving the model to increase its maximum possible luminosity. The results of application of the model to the ULX M82 X-2 and to other pulsed ULXs are presented.

  6. High sensitivity troponin and valvular heart disease.

    Science.gov (United States)

    McCarthy, Cian P; Donnellan, Eoin; Phelan, Dermot; Griffin, Brian P; Enriquez-Sarano, Maurice; McEvoy, John W

    2017-07-01

    Blood-based biomarkers have been extensively studied in a range of cardiovascular diseases and have established utility in routine clinical care, most notably in the diagnosis of acute coronary syndrome (e.g., troponin) and the management of heart failure (e.g., brain-natriuretic peptide). The role of biomarkers is less well established in the management of valvular heart disease (VHD), in which the optimal timing of surgical intervention is often challenging. One promising biomarker that has been the subject of a number of recent VHD research studies is high sensitivity troponin (hs-cTn). Novel high-sensitivity assays can detect subclinical myocardial damage in asymptomatic individuals. Thus, hs-cTn may have utility in the assessment of asymptomatic patients with severe VHD who do not have a clear traditional indication for surgical intervention. In this state-of-the-art review, we examine the current evidence for hs-cTn as a potential biomarker in the most commonly encountered VHD conditions, aortic stenosis and mitral regurgitation. This review provides a synopsis of early evidence indicating that hs-cTn has promise as a biomarker in VHD. However, the impact of its measurement on clinical practice and VHD outcomes needs to be further assessed in prospective studies before routine clinical use becomes a reality. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Magnetic separation using high-T sub c superconductors

    CERN Document Server

    Bolt, L

    2001-01-01

    sensitivity of the high-T sub c material to magnetic fields. Finite elements modelling of the system has provided the framework for the quantitative analysis of the magnetic field distributions on the coil windings and the optimisation of the system configuration. The performance of the separator has been tested at 77 K with liquid nitrogen at atmospheric pressure, and at a temperature approx = 67 K by pumping liquid nitrogen at a pressure around 100 Torr. The highest field obtained in the air gap at 67 K was of 340 mT. Magnetic separators with an iron circuit have been in operation for many years in mineral industry, and there appear to be an opportunity of building machines with high-T sub c coils or retrofitting existing machines with high-T sub c coils to run them closer to saturation in a cheap and effective way. Superconductivity has found in magnetic separation one of its major industrial applications second only to magnetic resonance imaging. Low-T sub c superconducting coils have been employed in Hig...

  8. Sensitive magnetic biodetection using magnetic multi-core nanoparticles and RCA coils

    Science.gov (United States)

    Ahrentorp, Fredrik; Blomgren, Jakob; Jonasson, Christian; Sarwe, Anna; Sepehri, Sobhan; Eriksson, Emil; Kalaboukhov, Alexei; Jesorka, Aldo; Winkler, Dag; Schneiderman, Justin F.; Nilsson, Mats; Albert, Jan; de la Torre, Teresa Zardán Gómez; Strømme, Maria; Johansson, Christer

    2017-04-01

    We use functionalized iron oxide magnetic multi-core particles of 100 nm in size (hydrodynamic particle diameter) and AC susceptometry (ACS) methods to measure the binding reactions between the magnetic nanoparticles (MNPs) and bio-analyte products produced from DNA segments using the rolling circle amplification (RCA) method. We use sensitive induction detection techniques in order to measure the ACS response. The DNA is amplified via RCA to generate RCA coils with a specific size that is dependent on the amplification time. After about 75 min of amplification we obtain an average RCA coil diameter of about 1 μm. We determine a theoretical limit of detection (LOD) in the range of 11 attomole (corresponding to an analyte concentration of 55 fM for a sample volume of 200 μL) from the ACS dynamic response after the MNPs have bound to the RCA coils and the measured ACS readout noise. We also discuss further possible improvements of the LOD.

  9. High temperature superconductors for magnetic suspension applications

    Science.gov (United States)

    Mcmichael, C. K.; Cooley, R. S.; Chen, Q. Y.; Ma, K. B.; Lamb, M. A.; Meng, R. L.; Chu, C. W.; Chu, W. K.

    1994-01-01

    High temperature superconductors (HTS) hold the promise for applications in magnetic levitation bearings, vibration damping, and torque coupling. Traditional magnetic suspension systems require active feedback and vibration controls in which power consumption and low frequency vibration are among the major engineering concerns. HTS materials have been demonstrated to be an enabling approach towards such problems due to their flux trapping properties. In our laboratory at TCSUH, we have been conducting a series of experiments to explore various mechanical applications using HTS. We have constructed a 30 lb. model flywheel levitated by a hybrid superconducting magnetic bearing (HSMB). We are also developing a levitated and vibration-dampled platform for high precision instrumentation. These applications would be ideal for space usages where ambient temperature is adequate for HTS to operate properly under greatly reduced cryogenic requirements. We will give a general overview of these potential applications and discuss the operating principles of the HTS devices we have developed.

  10. Highly Sensitive Electro-Optic Modulators

    Energy Technology Data Exchange (ETDEWEB)

    DeVore, Peter S [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-10-26

    There are very important diagnostic and communication applications that receive faint electrical signals to be transmitted over long distances for capture. Optical links reduce bandwidth and distance restrictions of metal transmission lines; however, such signals are only weakly imprinted onto the optical carrier, resulting in low fidelity transmission. Increasing signal fidelity often necessitates insertion of radio-frequency (RF) amplifiers before the electro-optic modulator, but (especially at high frequencies) RF amplification results in large irreversible distortions. We have investigated the feasibility of a Sensitive and Linear Modulation by Optical Nonlinearity (SALMON) modulator to supersede RF-amplified modulators. SALMON uses cross-phase modulation, a manifestation of the Kerr effect, to enhance the modulation depth of an RF-modulated optical wave. This ultrafast process has the potential to result in less irreversible distortions as compared to a RF-amplified modulator due to the broadband nature of the Kerr effect. Here, we prove that a SALMON modulator is a feasible alternative to an RFamplified modulator, by demonstrating a sensitivity enhancement factor greater than 20 and significantly reduced distortion.

  11. Probing Gravitational Sensitivity in Biological Systems Using Magnetic Body Forces

    Science.gov (United States)

    Valles, James; Guevorkian, Karine; Wurzel, Samuel; Mihalusova, Mariana

    2003-03-01

    We have commissioned a superconducting solenoid based apparatus designed to exert strong magnetic body forces on biological specimens and other organic materials in ambient environmental conditions for extended periods. In its room temperature bore, it can produce a maximum magnetic field-field gradient product of 16 T^2-cm-1 which is sufficient to levitate frog embryos Xenopus Laevis[1]. We will discuss how we are applying these magnetic body forces to probe the known influences of gravitational forces on frog embryos and the swimming behavior of Paramecium Caudatum. In the process, we will describe a novel method for measuring the diamagnetic susceptibilities of specimens such as paramecia.

  12. Physics of semiconductors in high magnetic fields

    CERN Document Server

    Miura, Noboru

    2008-01-01

    This book summarizes most of the fundamental physical phenomena which semiconductors and their modulated structures exhibit in high magnetic fields. Readers can learn not only the basic theoretical background but also the present state of the art from the most advanced data in this rapidly growing research area.

  13. High sensitive radiation detector for radiology dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Valente, M.; Malano, F. [Instituto de Fisica Enrique Gaviola, Oficina 102 FaMAF - UNC, Av. Luis Medina Allende, Ciudad Universitaria, 5000 Cordoba (Argentina); Molina, W.; Vedelago, J., E-mail: valente@famac.unc.edu.ar [Laboratorio de Investigaciones e Instrumentacion en Fisica Aplicada a la Medicina e Imagenes por Rayos X, Laboratorio 448 FaMAF - UNC, Ciudad Universitaria, 5000 Cordoba (Argentina)

    2014-08-15

    Fricke solution has a wide range of applications as radiation detector and dosimetry. It is particularly appreciated in terms of relevant comparative advantages, like tissue equivalence when prepared in aqueous media like gel matrix, continuous mapping capability, dose rate recorded and incident direction independence as well as linear dose response. This work presents the development and characterization of a novel Fricke gel system, based on modified chemical compositions making possible its application in clinical radiology. Properties of standard Fricke gel dosimeter for high dose levels are used as starting point and suitable chemical modifications are introduced and carefully investigated in order to attain high resolution for low dose ranges, like those corresponding to radiology interventions. The developed Fricke gel radiation dosimeter system achieves the expected typical dose dependency, actually showing linear response in the dose range from 20 up to 4000 mGy. Systematic investigations including several chemical compositions are carried out in order to obtain a good enough dosimeter response for low dose levels. A suitable composition among those studied is selected as a good candidate for low dose level radiation dosimetry consisting on a modified Fricke solution fixed to a gel matrix containing benzoic acid along with sulfuric acid, ferrous sulfate, xylenol orange and ultra-pure reactive grade water. Dosimeter samples are prepared in standard vials for its in phantom irradiation and further characterization by spectrophotometry measuring visible light transmission and absorbance before and after irradiation. Samples are irradiated by typical kV X-ray tubes and calibrated Farmer type ionization chamber is used as reference to measure dose rates inside phantoms in at vials locations. Once sensitive material composition is already optimized, dose-response curves show significant improvement regarding overall sensitivity for low dose levels. According to

  14. High sensitivity field asymmetric ion mobility spectrometer.

    Science.gov (United States)

    Chavarria, Mario A; Matheoud, Alessandro V; Marmillod, Philippe; Liu, Youjiang; Kong, Deyi; Brugger, Jürgen; Boero, Giovanni

    2017-03-01

    A high sensitivity field asymmetric ion mobility spectrometer (FAIMS) was designed, fabricated, and tested. The main components of the system are a 10.6 eV UV photoionization source, an ion filter driven by a high voltage/high frequency n-MOS inverter circuit, and a low noise ion detector. The ion filter electronics are capable to generate square waveforms with peak-to-peak voltages up to 1000 V at frequencies up to 1 MHz with adjustable duty cycles. The ion detector current amplifier has a gain up to 10 12 V/A with an effective equivalent input noise level down to about 1 fA/Hz 1/2 during operation with the ion filter at the maximum voltage and frequency. The FAIMS system was characterized by detecting different standard chemical compounds. Additionally, we investigated the use of a synchronous modulation/demodulation technique to improve the signal-to-noise ratio in FAIMS measurements. In particular, we implemented the modulation of the compensation voltage with the synchronous demodulation of the ion current. The analysis of the measurements at low concentration levels led to an extrapolated limit of detection for acetone of 10 ppt with an averaging time of 1 s.

  15. High sensitivity field asymmetric ion mobility spectrometer

    Science.gov (United States)

    Chavarria, Mario A.; Matheoud, Alessandro V.; Marmillod, Philippe; Liu, Youjiang; Kong, Deyi; Brugger, Jürgen; Boero, Giovanni

    2017-03-01

    A high sensitivity field asymmetric ion mobility spectrometer (FAIMS) was designed, fabricated, and tested. The main components of the system are a 10.6 eV UV photoionization source, an ion filter driven by a high voltage/high frequency n-MOS inverter circuit, and a low noise ion detector. The ion filter electronics are capable to generate square waveforms with peak-to-peak voltages up to 1000 V at frequencies up to 1 MHz with adjustable duty cycles. The ion detector current amplifier has a gain up to 1012 V/A with an effective equivalent input noise level down to about 1 fA/Hz1/2 during operation with the ion filter at the maximum voltage and frequency. The FAIMS system was characterized by detecting different standard chemical compounds. Additionally, we investigated the use of a synchronous modulation/demodulation technique to improve the signal-to-noise ratio in FAIMS measurements. In particular, we implemented the modulation of the compensation voltage with the synchronous demodulation of the ion current. The analysis of the measurements at low concentration levels led to an extrapolated limit of detection for acetone of 10 ppt with an averaging time of 1 s.

  16. Improving Magnet Designs With High and Low Field Regions

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Bahl, Christian Robert Haffenden; Smith, Anders

    2011-01-01

    A general scheme for increasing the difference in magnetic flux density between a high and a low magnetic field region by removing unnecessary magnet material is presented. This is important in, e.g., magnetic refrigeration where magnet arrays have to deliver high field regions in close proximity...... to low field regions. Also, a general way to replace magnet material with a high permeability soft magnetic material where appropriate is discussed. As an example, these schemes are applied to a two dimensional concentric Halbach cylinder design resulting in a reduction of the amount of magnet material...

  17. Magnetic and levitation characteristics of bulk high-temperature superconducting magnets above a permanent magnet guideway

    Science.gov (United States)

    Zheng, Jun; Zheng, Botian; He, Dabo; Sun, Ruixue; Deng, Zigang; Xu, Xun; Dou, Shixue

    2016-09-01

    Due to the large levitation force or the large guidance force of bulk high-temperature superconducting magnets (BHTSMs) above a permanent magnet guideway (PMG), it is reasonable to employ pre-magnetized BHTSMs to replace applied-magnetic-field-cooled superconductors in a maglev system. There are two combination modes between the BHTSM and the PMG, distinguished by the different directions of the magnetization. One is the S-S pole mode, and the other is the S-N pole mode combined with a unimodal PMG segment. A multi-point magnetic field measurement platform was employed to acquire the magnetic field signals of the BHTSM surface in real time during the pre-magnetization process and the re-magnetization process. Subsequently, three experimental aspects of levitation, including the vertical movement due to the levitation force, the lateral movement due to the guidance force, and the force relaxation with time, were explored above the PMG segment. Moreover, finite element modeling by COMSOL Multiphysics has been performed to simulate the different induced currents and the potentially different temperature rises with different modes inside the BHTSM. It was found that the S-S pole mode produced higher induced current density and a higher temperature rise inside the BHTSM, which might escalate its lateral instability above the PMG. The S-N pole mode exhibits the opposite characteristics. In general, this work is instructive for understanding and connecting the magnetic flux, the inner current density, the levitation behavior, and the temperature rise of BHTSMs employed in a maglev system.

  18. Enhancing the sensitivity of magnetic sensors by 3D metamaterial shells.

    Science.gov (United States)

    Navau, Carles; Mach-Batlle, Rosa; Parra, Albert; Prat-Camps, Jordi; Laut, Sergi; Del-Valle, Nuria; Sanchez, Alvaro

    2017-03-17

    Magnetic sensors are key elements in our interconnected smart society. Their sensitivity becomes essential for many applications in fields such as biomedicine, computer memories, geophysics, or space exploration. Here we present a universal way of increasing the sensitivity of magnetic sensors by surrounding them with a spherical metamaterial shell with specially designed anisotropic magnetic properties. We analytically demonstrate that the magnetic field in the sensing area is enhanced by our metamaterial shell by a known factor that depends on the shell radii ratio. When the applied field is non-uniform, as for dipolar magnetic field sources, field gradient is increased as well. A proof-of-concept experimental realization confirms the theoretical predictions. The metamaterial shell is also shown to concentrate time-dependent magnetic fields upto frequencies of 100 kHz.

  19. Iron oxide nanoparticle-micelles (ION-micelles for sensitive (molecular magnetic particle imaging and magnetic resonance imaging.

    Directory of Open Access Journals (Sweden)

    Lucas W E Starmans

    Full Text Available BACKGROUND: Iron oxide nanoparticles (IONs are a promising nanoplatform for contrast-enhanced MRI. Recently, magnetic particle imaging (MPI was introduced as a new imaging modality, which is able to directly visualize magnetic particles and could serve as a more sensitive and quantitative alternative to MRI. However, MPI requires magnetic particles with specific magnetic properties for optimal use. Current commercially available iron oxide formulations perform suboptimal in MPI, which is triggering research into optimized synthesis strategies. Most synthesis procedures aim at size control of iron oxide nanoparticles rather than control over the magnetic properties. In this study, we report on the synthesis, characterization and application of a novel ION platform for sensitive MPI and MRI. METHODS AND RESULTS: IONs were synthesized using a thermal-decomposition method and subsequently phase-transferred by encapsulation into lipidic micelles (ION-Micelles. Next, the material and magnetic properties of the ION-Micelles were analyzed. Most notably, vibrating sample magnetometry measurements showed that the effective magnetic core size of the IONs is 16 nm. In addition, magnetic particle spectrometry (MPS measurements were performed. MPS is essentially zero-dimensional MPI and therefore allows to probe the potential of iron oxide formulations for MPI. ION-Micelles induced up to 200 times higher signal in MPS measurements than commercially available iron oxide formulations (Endorem, Resovist and Sinerem and thus likely allow for significantly more sensitive MPI. In addition, the potential of the ION-Micelle platform for molecular MPI and MRI was showcased by MPS and MRI measurements of fibrin-binding peptide functionalized ION-Micelles (FibPep-ION-Micelles bound to blood clots. CONCLUSIONS: The presented data underlines the potential of the ION-Micelle nanoplatform for sensitive (molecular MPI and warrants further investigation of the Fib

  20. High-Sensitivity AGN Polarimetry at Sub-Millimeter Wavelengths

    Directory of Open Access Journals (Sweden)

    Ivan Martí-Vidal

    2017-10-01

    Full Text Available The innermost regions of radio loud Active Galactic Nuclei (AGN jets are heavily affected by synchrotron self-absorption, due to the strong magnetic fields and high particle densities in these extreme zones. The only way to overcome this absorption is to observe at sub-millimeter wavelengths, although polarimetric observations at such frequencies have so far been limited by sensitivity and calibration accuracy. However, new generation instruments such as the Atacama Large mm/sub-mm Array (ALMA overcome these limitations and are starting to deliver revolutionary results in the observational studies of AGN polarimetry. Here we present an overview of our state-of-the-art interferometric mm/sub-mm polarization observations of AGN jets with ALMA (in particular, the gravitationally-lensed sources PKS 1830−211 and B0218+359, which allow us to probe the magneto-ionic conditions at the regions closest to the central black holes.

  1. High magnetic field ohmically decoupled non-contact technology

    Science.gov (United States)

    Wilgen, John [Oak Ridge, TN; Kisner, Roger [Knoxville, TN; Ludtka, Gerard [Oak Ridge, TN; Ludtka, Gail [Oak Ridge, TN; Jaramillo, Roger [Knoxville, TN

    2009-05-19

    Methods and apparatus are described for high magnetic field ohmically decoupled non-contact treatment of conductive materials in a high magnetic field. A method includes applying a high magnetic field to at least a portion of a conductive material; and applying an inductive magnetic field to at least a fraction of the conductive material to induce a surface current within the fraction of the conductive material, the surface current generating a substantially bi-directional force that defines a vibration. The high magnetic field and the inductive magnetic field are substantially confocal, the fraction of the conductive material is located within the portion of the conductive material and ohmic heating from the surface current is ohmically decoupled from the vibration. An apparatus includes a high magnetic field coil defining an applied high magnetic field; an inductive magnetic field coil coupled to the high magnetic field coil, the inductive magnetic field coil defining an applied inductive magnetic field; and a processing zone located within both the applied high magnetic field and the applied inductive magnetic field. The high magnetic field and the inductive magnetic field are substantially confocal, and ohmic heating of a conductive material located in the processing zone is ohmically decoupled from a vibration of the conductive material.

  2. [Sensitivity of the diamagnetic condensed matter to weak magnetic fields].

    Science.gov (United States)

    Kartashov, Iu A; Popov, I V

    2008-01-01

    It is shown that, under the influence of magnetic field, rotational moments of the same direction appear for all charged particles having the same sign of their charge and freely moving in a thermal fluctuational electromagnetic field in a diamagnetic condensed matter. The magnitude of this rotational moment is proportional to the thermal energy kT and can be substantially increased when the conditions for cyclotron resonance are satisfied. The moments of positively charged particles are directed oppositely to the vector of the magnetic field induction. The so-called "kT problem" has been solved. The evidence for magnetosensitivity is the appearance of rotational moments acting on the particles from the thermal field in the presence of an external magnetic field as a small factor.

  3. Permanent magnet design for high-speed superconducting bearings

    Science.gov (United States)

    Hull, John R.; Uherka, Kenneth L.; Abdoud, Robert G.

    1996-01-01

    A high temperature superconducting bearing including a permanent magnet rotor levitated by a high temperature superconducting structure. The rotor preferably includes one or more concentric permanent magnet rings coupled to permanent magnet ring structures having substantially triangular and quadrangular cross-sections. Both alternating and single direction polarity magnet structures can be used in the bearing.

  4. Development of high sensitivity radon detectors

    CERN Document Server

    Takeuchi, Y; Kajita, T; Tasaka, S; Hori, H; Nemoto, M; Okazawa, H

    1999-01-01

    High sensitivity detectors for radon in air and in water have been developed. We use electrostatic collection and a PIN photodiode for these detectors. Calibration systems have been also constructed to obtain collection factors. As a result of the calibration study, the absolute humidity dependence of the radon detector for air is clearly observed in the region less than about 1.6 g/m sup 3. The calibration factors of the radon detector for air are 2.2+-0.2 (counts/day)/(mBq/m sup 3) at 0.08 g/m sup 3 and 0.86+-0.06 (counts/day)/(mBq/m sup 3) at 11 g/m sup 3. The calibration factor of the radon detector for water is 3.6+-0.5 (counts/day)/(mBq/m sup 3). The background level of the radon detector for air is 2.4+-1.3 counts/day. As a result, one standard deviation excess of the signal above the background of the radon detector for air should be possible for 1.4 mBq/m sup 3 in a one-day measurement at 0.08 g/m sup 3.

  5. A sensitive magnetic field sensor using BPSCCO thick film

    Indian Academy of Sciences (India)

    Unknown

    ), magnetic bearings (Itoh ... (Gallop et al 1989; Gielisse et al 1991; Khare et al 1997;. Dey et al 1999), those based on the sharp jump of .... Gielisse P J, Niculescu H, Roy B, Jones K W, Larkin G and. Hu Z 1991 Supercond. Sci. Technol. 4 416.

  6. Probing Gravitational Sensitivity in Biological Systems Using Magnetic Body Forces

    Science.gov (United States)

    Guevorkian, Karine; Wurzel, Sam; Mihalusova, Mariana; Valles, Jim

    2003-01-01

    At Brown University, we are developing the use of magnetic body forces as a means to simulate variable gravity body forces on biological systems. This tool promises new means to probe gravi-sensing and the gravi-response of biological systems. It also has the potential as a technique for screening future systems for space flight experiments.

  7. Dynamic nuclear polarization at high magnetic fields.

    Science.gov (United States)

    Maly, Thorsten; Debelouchina, Galia T; Bajaj, Vikram S; Hu, Kan-Nian; Joo, Chan-Gyu; Mak-Jurkauskas, Melody L; Sirigiri, Jagadishwar R; van der Wel, Patrick C A; Herzfeld, Judith; Temkin, Richard J; Griffin, Robert G

    2008-02-07

    Dynamic nuclear polarization (DNP) is a method that permits NMR signal intensities of solids and liquids to be enhanced significantly, and is therefore potentially an important tool in structural and mechanistic studies of biologically relevant molecules. During a DNP experiment, the large polarization of an exogeneous or endogeneous unpaired electron is transferred to the nuclei of interest (I) by microwave (microw) irradiation of the sample. The maximum theoretical enhancement achievable is given by the gyromagnetic ratios (gamma(e)gamma(l)), being approximately 660 for protons. In the early 1950s, the DNP phenomenon was demonstrated experimentally, and intensively investigated in the following four decades, primarily at low magnetic fields. This review focuses on recent developments in the field of DNP with a special emphasis on work done at high magnetic fields (> or =5 T), the regime where contemporary NMR experiments are performed. After a brief historical survey, we present a review of the classical continuous wave (cw) DNP mechanisms-the Overhauser effect, the solid effect, the cross effect, and thermal mixing. A special section is devoted to the theory of coherent polarization transfer mechanisms, since they are potentially more efficient at high fields than classical polarization schemes. The implementation of DNP at high magnetic fields has required the development and improvement of new and existing instrumentation. Therefore, we also review some recent developments in microw and probe technology, followed by an overview of DNP applications in biological solids and liquids. Finally, we outline some possible areas for future developments.

  8. Magnetic field distribution of strong hybrid magnet in high torque motor

    Science.gov (United States)

    Oguri, Kazuya; Mizutani, Akihiro; Ogino, Sanshiroh; Ochiai, Yasuzumi; Kawahata, Masahiro; Nishi, Yoshitake

    2002-11-01

    A variable reluctance hybrid magnet has been developed to apply new type of high torque motors. A permanent magnet, electromagnet and yoke construct the variable reluctance hybrid magnet. From an engineering point of view, it is important to know the magnetic field around a variable reluctance hybrid magnet. Based on the results of magnetic flux density measurement around the hybrid variable reluctance magnet, the high magnetic flux density was found at edges and joints. The high magnetic flux density was also obtained with electrical current of 10 A at optimum setting form. Therefore, we concluded that the strong force of rotor of the hybrid motor was generated by high surface flux density of the hybrid magnet.

  9. Detecting the gravitational sensitivity of Paramecium caudatum using magnetic forces

    Science.gov (United States)

    Guevorkian, Karine; Valles, James M., Jr.

    2006-03-01

    Under normal conditions, Paramecium cells regulate their swimming speed in response to the pN level mechanical force of gravity. This regulation, known as gravikinesis, is more pronounced when the external force is increased by methods such as centrifugation. Here we present a novel technique that simulates gravity fields using the interactions between strong inhomogeneous magnetic fields and cells. We are able to achieve variable gravities spanning from 10xg to -8xg; where g is earth's gravity. Our experiments show that the swimming speed regulation of Paramecium caudatum to magnetically simulated gravity is a true physiological response. In addition, they reveal a maximum propulsion force for paramecia. This advance establishes a general technique for applying continuously variable forces to cells or cell populations suitable for exploring their force transduction mechanisms.

  10. Magnetic matrices used in high gradient magnetic separation (HGMS: A review

    Directory of Open Access Journals (Sweden)

    Wei Ge

    Full Text Available HGMS is effective in separating or filtering fine and weakly magnetic particles and widely applied in mineral processing, water treatment, cell and protein purification. The magnetic matrix is a crucial device used in magnetic separator to generate high magnetic field gradient and provide surface sites for capturing magnetic particles. The material, geometry, size and arrangement of the matrix elements can significantly affect the gradient and distribution of the magnetic field, and the separating or filtrating performance. In this paper, the researches and developments of magnetic matrices used in HGMS are reviewed. Keywords: Magnetic matrix, HGMS, Review

  11. Sensitive element of multifunctional sensor for measuring temperature, strain and magnetic field induction

    Directory of Open Access Journals (Sweden)

    Druzhinin A. A.

    2017-12-01

    Full Text Available Sensitive element of multifunctional sensor for measuring temperature, strain and magnetic field induction has been developed based on the studies of electrical conductivity and magnetoresistance of silicon and germanium microcrystals in the temperature range 4.2—70 K, strain ±1.5*10–3 rel.un. and magnetic fields of 0—14 T. The feature of the sensitive element is the using of the p- and n-type conductivity germanium microcrystals as mechanical and magnetic field sensors, respectively, and the p-type silicon microcrystal — as temperature sensor. That allows providing the compensation of temperature influence on piezoresistance and on sensitivity to the magnetic field.

  12. Fabrication Technology and Characteristics of a Magnetic Sensitive Transistor with nc-Si:H/c-Si Heterojunction

    Directory of Open Access Journals (Sweden)

    Xiaofeng Zhao

    2017-01-01

    Full Text Available This paper presents a magnetically sensitive transistor using a nc-Si:H/c-Si heterojunction as an emitter junction. By adopting micro electro-mechanical systems (MEMS technology and chemical vapor deposition (CVD method, the nc-Si:H/c-Si heterojunction silicon magnetically sensitive transistor (HSMST chips were designed and fabricated on a p-type <100> orientation double-side polished silicon wafer with high resistivity. In addition, a collector load resistor ( R L was integrated on the chip, and the resistor converted the collector current ( I C to a collector output voltage ( V out . When I B = 8.0 mA, V DD = 10.0 V, and R L = 4.1 kΩ, the magnetic sensitivity ( S V at room temperature and temperature coefficient ( α C of the collector current for HSMST were 181 mV/T and −0.11%/°C, respectively. The experimental results show that the magnetic sensitivity and temperature characteristics of the proposed transistor can be obviously improved by the use of a nc-Si:H/c-Si heterojunction as an emitter junction.

  13. Fabrication Technology and Characteristics of a Magnetic Sensitive Transistor with nc-Si:H/c-Si Heterojunction.

    Science.gov (United States)

    Zhao, Xiaofeng; Li, Baozeng; Wen, Dianzhong

    2017-01-22

    This paper presents a magnetically sensitive transistor using a nc-Si:H/c-Si heterojunction as an emitter junction. By adopting micro electro-mechanical systems (MEMS) technology and chemical vapor deposition (CVD) method, the nc-Si:H/c-Si heterojunction silicon magnetically sensitive transistor (HSMST) chips were designed and fabricated on a p-type orientation double-side polished silicon wafer with high resistivity. In addition, a collector load resistor ( R L ) was integrated on the chip, and the resistor converted the collector current ( I C ) to a collector output voltage ( V out ). When I B = 8.0 mA, V DD = 10.0 V, and R L = 4.1 kΩ, the magnetic sensitivity ( S V ) at room temperature and temperature coefficient ( α C ) of the collector current for HSMST were 181 mV/T and -0.11%/°C, respectively. The experimental results show that the magnetic sensitivity and temperature characteristics of the proposed transistor can be obviously improved by the use of a nc-Si:H/c-Si heterojunction as an emitter junction.

  14. Magnetic/pH-sensitive κ-carrageenan/sodium alginate hydrogel nanocomposite beads: preparation, swelling behavior, and drug delivery.

    Science.gov (United States)

    Mahdavinia, Gholam Reza; Rahmani, Zeinab; Karami, Shiva; Pourjavadi, Ali

    2014-01-01

    This work describes the preparation of magnetic and pH-sensitive beads based on κ-carrageenan and sodium alginate for use as drug-targeting carriers. Physical cross-linking using K(+)/Ca(2+) ions was applied to obtain ionic cross-linked magnetic hydrogel beads. The produced magnetite beads were thoroughly characterized by TEM, SEM/EDS, XRD, FTIR, and VSM techniques. While the water absorbency (WA) of magnetic beads was enhanced by increasing the weight ratio of κ-carrageenan, introducing magnetic nanoparticles caused a decrease in WA capacity from 15.4 to 6.3 g/g. Investigation on the swelling of the hydrogel beads in NaCl, KCl, and CaCl2 solutions revealed the disintegration of beads depending on the composition of hydrogel beads and the type of metal cations in swelling media. The swelling ratio of beads indicated pH-dependent properties with maximum water absorbing at pH 7.4. Also, it was found that the strength of pH-sensitivity of magnetic beads was low for beads with the high content of carrageenan component. The in vitro drug release studies from hydrogels exhibited significant behaviors on the subject of physiological-simulated pH values and external magnetic fields. The maximum cumulative releases obtained were 98 and 43% at pH values 7.4 and 1.2, respectively. The Introducing magnetite nanoparticles influenced the cumulative release of drug.

  15. Spontaneous magnetization in high-density quark matter

    DEFF Research Database (Denmark)

    Tsue, Yasuhiko; da Providência, João; Providência, Constanca

    2015-01-01

    It is shown that spontaneous magnetization occurs due to the anomalous magnetic moments of quarks in high-density quark matter under the tensor-type four-point interaction. The spin polarized condensate for each flavor of quark appears at high baryon density, which leads to the spontaneous...... magnetization due to the anomalous magnetic moments of quarks. The implications for the strong magnetic field in compact stars is discussed....

  16. High Radiation Environment Nuclear Fragment Separator Magnet

    Energy Technology Data Exchange (ETDEWEB)

    Kahn, Stephen [Muons, Inc., Batavia, IL (United States); Gupta, Ramesh [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-01-31

    Superconducting coils wound with HTS conductor can be used in magnets located in a high radiation environment. NbTi and Nb3Sn superconductors must operate at 4.5 K or below where removal of heat is less efficient. The HTS conductor can carry significant current at higher temperatures where the Carnot efficiency is significantly more favorable and where the coolant heat capacity is much larger. Using the HTS conductor the magnet can be operated at 40 K. This project examines the use of HTS conductor for the Michigan State University Facility For Rare Isotope Beams (FRIB) fragment separator dipole magnet which bends the beam by 30° and is located in a high radiation region that will not be easily accessible. Two of these magnets are needed to select the chosen isotope. There are a number of technical challenges to be addressed in the design of this magnet. The separator dipole is 2 m long and subtends a large angle. The magnet should keep a constant transverse field profile along its beam reference path. Winding coils with a curved inner segment is difficult as the conductor will tend to unwind during the process. In the Phase I project two approaches to winding the conductor were examined. The first was to wind the coils with curved sections on the inner and outer segments with the inner segment wound with negative curvature. The alternate approach was to use a straight segment on the inner segment to avoid negative curvature. In Phase I coils with a limited number of turns were successfully wound and tested at 77 K for both coil configurations. The Phase II program concentrated on the design, coil winding procedures, structural analysis, prototyping and testing of an HTS curved dipole coil at 40 K with a heat load representative of the radiation environment. One of the key criteria of the design of this magnet is to avoid the use of organic materials that would degrade rapidly in radiation. The Lorentz forces expected from the coils interacting with the

  17. Dandelions, tulips and orchids: evidence for the existence of low-sensitive, medium-sensitive and high-sensitive individuals.

    Science.gov (United States)

    Lionetti, Francesca; Aron, Arthur; Aron, Elaine N; Burns, G Leonard; Jagiellowicz, Jadzia; Pluess, Michael

    2018-01-22

    According to empirical studies and recent theories, people differ substantially in their reactivity or sensitivity to environmental influences with some being generally more affected than others. More sensitive individuals have been described as orchids and less-sensitive ones as dandelions. Applying a data-driven approach, we explored the existence of sensitivity groups in a sample of 906 adults who completed the highly sensitive person (HSP) scale. According to factor analyses, the HSP scale reflects a bifactor model with a general sensitivity factor. In contrast to prevailing theories, latent class analyses consistently suggested the existence of three rather than two groups. While we were able to identify a highly sensitive (orchids, 31%) and a low-sensitive group (dandelions, 29%), we also detected a third group (40%) characterised by medium sensitivity, which we refer to as tulips in keeping with the flower metaphor. Preliminary cut-off scores for all three groups are provided. In order to characterise the different sensitivity groups, we investigated group differences regarding the Big Five personality traits, as well as experimentally assessed emotional reactivity in an additional independent sample. According to these follow-up analyses, the three groups differed in neuroticism, extraversion and emotional reactivity to positive mood induction with orchids scoring significantly higher in neuroticism and emotional reactivity and lower in extraversion than the other two groups (dandelions also differed significantly from tulips). Findings suggest that environmental sensitivity is a continuous and normally distributed trait but that people fall into three distinct sensitive groups along a sensitivity continuum.

  18. High sensitivity optical measurement of skin gloss

    NARCIS (Netherlands)

    Ezerskaia, A.; Ras, Arno; Bloemen, Pascal; Pereira, S.F.; Urbach, Paul; Varghese, Babu

    2017-01-01

    We demonstrate a low-cost optical method for measuring the gloss properties with improved sensitivity in the low gloss regime, relevant for skin gloss properties. The gloss estimation method is based on, on the one hand, the slope of the intensity gradient in the transition regime between

  19. Environmental Sensitivity in Children: Development of the Highly Sensitive Child Scale and Identification of Sensitivity Groups

    Science.gov (United States)

    Pluess, Michael; Assary, Elham; Lionetti, Francesca; Lester, Kathryn J.; Krapohl, Eva; Aron, Elaine N.; Aron, Arthur

    2018-01-01

    A large number of studies document that children differ in the degree they are shaped by their developmental context with some being more sensitive to environmental influences than others. Multiple theories suggest that "Environmental Sensitivity" is a common trait predicting the response to negative as well as positive exposures.…

  20. A permanent magnet device for producing variable high magnetic field in three dimensions

    CERN Document Server

    Hwang, C S; Chang, P C; Chen, H H; Chang, C H; Huang Ming Hsiung

    2000-01-01

    By combining four parallel rows of permanent magnet blocks, a magnet device that can produce variable high magnetic field in three dimensions has been designed. In this device, the magnetic field direction and strength can be varied by shifting the four rows along their longitudinal direction and by varying the magnet gap between the top and bottom rows. With a magnet gap of 10 mm, the magnetic field strength at the center of the device is about 1.4 T along the longitudinal and two transverse directions. This device can be utilized in X-ray magnetic circular dichroism and X-ray magnetic linear dichroism experiments as well as in other applications where a variable high magnetic field in three dimensions is needed.

  1. Ultra-sensitive Magnetic Microscopy with an Atomic Magnetometer

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Jin [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-08-19

    The PowerPoint presentation focused on research goals, specific information about the atomic magnetometer, response and resolution factors of the SERF magnetometer, FC+AM systems, tests of field transfer and resolution on FC, gradient cancellation, testing of AM performance, ideas for a multi-channel AM, including preliminary sensitivity testing, and a description of a 6 channel DAQ system. A few ideas for future work ended the presentation.

  2. Hybrid Superconducting Magnetic Bearing (HSMB) for high load devices

    Science.gov (United States)

    Mcmichael, C. K.; Ma, K. B.; Lamb, M. A.; Lin, M. W.; Chow, L.; Meng, R. L.; Hor, P. H.; Chu, W. K.

    1992-01-01

    Lifting capacities greater than 41 N/cm(exp 2) (60 psi) at 77 K have been achieved with a new type of levitation (hybrid) using a combination of permanent magnets and high quality melt-mixtured YBa2Cu3O(7-delta) (YBCO). The key concept of the hybrid superconducting magnetic bearing (HSMB) is the use of strong magnetic repulsion and attraction from permanent magnets for high levitation or suspension forces in conjunction with a superconductor's flux pinning characteristics to counteract the inherent instabilities in a system consisting of magnets only. To illustrate this concept, radial and axial forces between magnet/superconductor, magnet/magnet, and magnet/superconductor/magnet, were measured and compared for the thrust bearing configuration

  3. Billion-Fold Enhancement in Sensitivity of Nuclear Magnetic Resonance Spectroscopy for Magnesium Ions in Solution

    CERN Document Server

    Gottberg, Alexander; Kowalska, Magdalena; Bissell, Mark L; Arcisauskaite, Vaida; Blaum, Klaus; Helmke, Alexander; Johnston, Karl; Kreim, Kim; Larsen, Flemming H; Neugart, Rainer; Neyens, Gerda; Garcia Ruiz, Ronald F; Szunyogh, Daniel; Thulstrup, Peter W; Yordanov, Deyan T; Hemmingsen, Lars

    2014-01-01

    β-nuclear magnetic resonance (NMR) spectroscopy is highly sensitive compared to conventional NMR spectroscopy, and may be applied for several elements across the periodic table. β-NMR has previously been successfully applied in the fields of nuclear and solid-state physics. In this work, β-NMR is applied, for the first time, to record an NMR spectrum for a species in solution. 31Mg β-NMR spectra are measured for as few as 107 magnesium ions in ionic liquid (EMIM-Ac) within minutes, as a prototypical test case. Resonances are observed at 3882.9 and 3887.2 kHz in an external field of 0.3 T. The key achievement of the current work is to demonstrate that β-NMR is applicable for the analysis of species in solution, and thus represents a novel spectroscopic technique for use in general chemistry and potentially in biochemistry.

  4. Mitigated-force carriage for high magnetic field environments

    Science.gov (United States)

    Ludtka, Gerard M.; Ludtka, Gail M.; Wilgen, John B.; Murphy, Bart L.

    2015-05-19

    A carriage for high magnetic field environments includes a plurality of work-piece separators disposed in an operable relationship with a work-piece processing magnet having a magnetic field strength of at least 1 Tesla for supporting and separating a plurality of work-pieces by a preselected, essentially equal spacing, so that, as a first work-piece is inserted into the magnetic field, a second work-piece is simultaneously withdrawn from the magnetic field, so that an attractive magnetic force imparted on the first work-piece offsets a resistive magnetic force imparted on the second work-piece.

  5. Mismatch negativity (MMN) in high and low noise sensitive individuals

    NARCIS (Netherlands)

    White, Kim; Meeter, Martijn

    2015-01-01

    Although noise sensitivity is known to be an important determinant of noise annoyance, its neural underpinnings are not yet well established. In the present study, high and low noise sensitive participants were selected based on their scores on the Noise Sensitivity Scale (NSS) and the Noise

  6. High performance hybrid magnetic structure for biotechnology applications

    Science.gov (United States)

    Humphries, David E [El Cerrito, CA; Pollard, Martin J [El Cerrito, CA; Elkin, Christopher J [San Ramon, CA

    2009-02-03

    The present disclosure provides a high performance hybrid magnetic structure made from a combination of permanent magnets and ferromagnetic pole materials which are assembled in a predetermined array. The hybrid magnetic structure provides means for separation and other biotechnology applications involving holding, manipulation, or separation of magnetic or magnetizable molecular structures and targets. Also disclosed are further improvements to aspects of the hybrid magnetic structure, including additional elements and for adapting the use of the hybrid magnetic structure for use in biotechnology and high throughput processes.

  7. Alignment of molecular materials in high magnetic fields

    NARCIS (Netherlands)

    Christianen, P.C.M.; Shklyarevskiy, O.I.; Boamfa, M.I.; Maan, J.C.

    2004-01-01

    The potential of using high magnetic fields to align functional molecular materials is discussed, illustrated by magnetic orientation of two different types of materials. Alignment of side chain polymer liquid crystals leads to macroscopically ordered, transparant and strongly birefringent material.

  8. Enhanced Energy Density in Permanent Magnets using Controlled High Magnetic Field during Processing

    Energy Technology Data Exchange (ETDEWEB)

    Carter, William G [ORNL; Rios, Orlando [ORNL; Constantinides, Steven [ORNL

    2016-05-05

    This ORNL Manufacturing Demonstraction Facility (MDF) technical collaboration focused on the use of high magnetic field processing (>2Tesla) using energy efficient large bore superconducting magnet technology and high frequency electromagnetics to improve magnet performance and reduce the energy budget associated with Alnico thermal processing. Alnico, alloys containing Al, Ni, Co and Fe, represent a class of functional nanostructured alloys, and show the greatest potential for supplementing or replacing commercial Nd-based rare-earth alloy magnets.

  9. Simulations of magnetic hysteresis loops at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Plumer, M. L.; Whitehead, J. P.; Fal, T. J. [Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John' s, Newfoundland and Labrador A1B 3X7 (Canada); Ek, J. van [Western Digital Corporation, San Jose, California 94588 (United States); Mercer, J. I. [Department of Computer Science, Memorial University of Newfoundland, St. John' s, Newfoundland and Labrador A1B 3X7 (Canada)

    2014-09-28

    The kinetic Monte-Carlo algorithm as well as standard micromagnetics are used to simulate MH loops of high anisotropy magnetic recording media at both short and long time scales over a wide range of temperatures relevant to heat-assisted magnetic recording. Microscopic parameters, common to both methods, were determined by fitting to experimental data on single-layer FePt-based media that uses the Magneto-Optic Kerr effect with a slow sweep rate of 700 Oe/s. Saturation moment, uniaxial anisotropy, and exchange constants are given an intrinsic temperature dependence based on published atomistic simulations of FePt grains with an effective Curie temperature of 680 K. Our results show good agreement between micromagnetics and kinetic Monte Carlo results over a wide range of sweep rates. Loops at the slow experimental sweep rates are found to become more square-shaped, with an increasing slope, as temperature increases from 300 K. These effects also occur at higher sweep rates, typical of recording speeds, but are much less pronounced. These results demonstrate the need for accurate determination of intrinsic thermal properties of future recording media as input to micromagnetic models as well as the sensitivity of the switching behavior of thin magnetic films to applied field sweep rates at higher temperatures.

  10. Development of Position-Sensitive Magnetic Calorimeters for X-Ray Astronomy

    Science.gov (United States)

    Bandler, SImon; Stevenson, Thomas; Hsieh, Wen-Ting

    2011-01-01

    Metallic magnetic calorimeters (MMC) are one of the most promising devices to provide very high energy resolution needed for future astronomical x-ray spectroscopy. MMC detectors can be built to large detector arrays having thousands of pixels. Position-sensitive magnetic (PoSM) microcalorimeters consist of multiple absorbers thermally coupled to one magnetic micro calorimeter. Each absorber element has a different thermal coupling to the MMC, resulting in a distribution of different pulse shapes and enabling position discrimination between the absorber elements. PoSMs therefore achieve the large focal plane area with fewer number of readout channels without compromising spatial sampling. Excellent performance of PoSMs was achieved by optimizing the designs of key parameters such as the thermal conductance among the absorbers, magnetic sensor, and heat sink, as well as the absorber heat capacities. Micro fab ri - cation techniques were developed to construct four-absorber PoSMs, in which each absorber consists of a two-layer composite of bismuth and gold. The energy resolution (FWHM full width at half maximum) was measured to be better than 5 eV at 6 keV x-rays for all four absorbers. Position determination was demonstrated with pulse-shape discrimination, as well as with pulse rise time. X-ray microcalorimeters are usually designed to thermalize as quickly as possible to avoid degradation in energy resolution from position dependence to the pulse shapes. Each pixel consists of an absorber and a temperature sensor, both decoupled from the cold bath through a weak thermal link. Each pixel requires a separate readout channel; for instance, with a SQUID (superconducting quantum interference device). For future astronomy missions where thousands to millions of resolution elements are required, having an individual SQUID readout channel for each pixel becomes difficult. One route to attaining these goals is a position-sensitive detector in which a large continuous or

  11. Nitrogen detected TROSY at high field yields high resolution and sensitivity for protein NMR.

    Science.gov (United States)

    Takeuchi, Koh; Arthanari, Haribabu; Shimada, Ichio; Wagner, Gerhard

    2015-12-01

    Detection of (15)N in multidimensional NMR experiments of proteins has sparsely been utilized because of the low gyromagnetic ratio (γ) of nitrogen and the presumed low sensitivity of such experiments. Here we show that selecting the TROSY components of proton-attached (15)N nuclei (TROSY (15)NH) yields high quality spectra in high field magnets (>600 MHz) by taking advantage of the slow (15)N transverse relaxation and compensating for the inherently low (15)N sensitivity. The (15)N TROSY transverse relaxation rates increase modestly with molecular weight but the TROSY gain in peak heights depends strongly on the magnetic field strength. Theoretical simulations predict that the narrowest line width for the TROSY (15)NH component can be obtained at 900 MHz, but sensitivity reaches its maximum around 1.2 GHz. Based on these considerations, a (15)N-detected 2D (1)H-(15)N TROSY-HSQC ((15)N-detected TROSY-HSQC) experiment was developed and high-quality 2D spectra were recorded at 800 MHz in 2 h for 1 mM maltose-binding protein at 278 K (τc ~ 40 ns). Unlike for (1)H detected TROSY, deuteration is not mandatory to benefit (15)N detected TROSY due to reduced dipolar broadening, which facilitates studies of proteins that cannot be deuterated, especially in cases where production requires eukaryotic expression systems. The option of recording (15)N TROSY of proteins expressed in H2O media also alleviates the problem of incomplete amide proton back exchange, which often hampers the detection of amide groups in the core of large molecular weight proteins that are expressed in D2O culture media and cannot be refolded for amide back exchange. These results illustrate the potential of (15)NH-detected TROSY experiments as a means to exploit the high resolution offered by high field magnets near and above 1 GHz.

  12. SQUID magnetometer using sensitivity correction signal for non-magnetic metal contaminants detection

    Energy Technology Data Exchange (ETDEWEB)

    Yagi, Toshifumi, E-mail: sakuta.k@usp.ac.jp; Ohashi, Masaharu; Sakuta, Ken

    2016-11-15

    Highlights: • A high-frequency excitation is necessary to detect nonmagnetic metals using SQUID. • It is possible to detect a high-frequency magnetic field using the open loop technique. • Open loop operation leads to a change in the conversion factor. • Conversion between voltage and magnetic field for open loop operation are examined. - Abstract: Measurement methods with SQUID can accurately detect small magnetic metal contaminants based on their magnetic remanence. But, a high-frequency excitation is necessary to detect nonmagnetic metals, on the base of contrasts in electric conductivity. In this work, an open loop technique is introduced to facilitate this. The SQUID is negative feedback controlled (flux locked loop (FLL) operation) for the low frequency range, which includes significant noise due to the movement of the magnetic body or the change of the ambient magnetic field composed of the geomagnetic field and technical signals, and it operates in an open loop configuration for the high frequency range. When using the open loop technique, negative feedback is not applied to the high frequency range. Consequently, the V–Φ characteristic changes due to various causes, which leads to variations in the conversion factor between the SQUID output voltage and the magnetic field. In this study, conversion techniques for the magnetic field for open loop operation of SQUID in the high frequency range are examined.

  13. Voltage-sensitive dye imaging of transcranial magnetic stimulation-induced intracortical dynamics.

    Science.gov (United States)

    Kozyrev, Vladislav; Eysel, Ulf T; Jancke, Dirk

    2014-09-16

    Transcranial magnetic stimulation (TMS) is widely used in clinical interventions and basic neuroscience. Additionally, it has become a powerful tool to drive plastic changes in neuronal networks. However, highly resolved recordings of the immediate TMS effects have remained scarce, because existing recording techniques are limited in spatial or temporal resolution or are interfered with by the strong TMS-induced electric field. To circumvent these constraints, we performed optical imaging with voltage-sensitive dye (VSD) in an animal experimental setting using anaesthetized cats. The dye signals reflect gradual changes in the cells' membrane potential across several square millimeters of cortical tissue, thus enabling direct visualization of TMS-induced neuronal population dynamics. After application of a single TMS pulse across visual cortex, brief focal activation was immediately followed by synchronous suppression of a large pool of neurons. With consecutive magnetic pulses (10 Hz), widespread activity within this "basin of suppression" increased stepwise to suprathreshold levels and spontaneous activity was enhanced. Visual stimulation after repetitive TMS revealed long-term potentiation of evoked activity. Furthermore, loss of the "deceleration-acceleration" notch during the rising phase of the response, as a signature of fast intracortical inhibition detectable with VSD imaging, indicated weakened inhibition as an important driving force of increasing cortical excitability. In summary, our data show that high-frequency TMS changes the balance between excitation and inhibition in favor of an excitatory cortical state. VSD imaging may thus be a promising technique to trace TMS-induced changes in excitability and resulting plastic processes across cortical maps with high spatial and temporal resolutions.

  14. Magnetic force microscopy of thin film media for high density magnetic recording

    NARCIS (Netherlands)

    Porthun, Steffen; Porthun, S.; Abelmann, Leon; Lodder, J.C.

    1998-01-01

    This paper discusses various aspect of magnetic force microscopy (MFM) for use in the field of high density magnetic recording. After an introduction of the most important magnetic imaging techniques, an overview is given of the operation and theory of MFM. The developments in instrumentation, MFM

  15. Magnetic and Magneto-Optical Properties in Paramagnetic NdF3 Under High Magnetic Field

    Science.gov (United States)

    Wang, Wei; Liu, Gong-Qiang

    2005-05-01

    In this paper, we first theoretically report the magnetic and magneto-optical properties in paramagnetic media under high external magnetic field. Considering the action of the external magnetic field He and indirect exchange interaction Hv, the characteristic of the magnetic saturation and the property of the Faraday rotation to be nonlinear with external magnetic field are presented in paramagnetic NdF3. In terms of our theory, the indirect exchange interaction plays an important role in the magnetization M and the Faraday rotation θ in NdF3 under high external magnetic field. The theory is in good agreement with experimental results. On the other hand, a reasonable explanation for the temperature dependence of the ratio of the Verdet constant to the magnetic susceptibility V/χ is obtained.

  16. High temperature radio-frequency superconducting quantum interference device system for detection of magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Pretzell, Alf

    2012-07-01

    This doctoral thesis was aimed at establishing a set-up with high-temperature superconductor (HTS) radio-frequency (rf) superconducting quantum interference device (SQUID) technology for the detection of magnetic nanoparticles and in particular for testing applications of magnetic nanoparticle immunoassays. It was part of the EU-project ''Biodiagnostics'' running from 2005 to 2008. The method of magnetic binding assays was developed as an alternative to other methods of concentration determination like enzyme linked immunosorbent assay (ELISA), or fluorescent immunoassay. The ELISA has sensitivities down to analyte-concentrations of pg/ml. Multiple incubation and washing steps have to be performed for these techniques, the analyte has to diffuse to the site of binding. The magnetic assay uses magnetic nanoparticles as markers for the substance to be detected. It is being explored by current research and shows similar sensitivity compared to ELISA but in contrast - does not need any washing and can be read out directly after binding - can be applied in solution with opaque media, e.g. blood or muddy water - additionally allows magnetic separation or concentration - in combination with small magnetoresistive or Hall sensors, allows detection of only a few particles or even single beads. For medical or environmental samples, maybe opaque and containing a multitude of substances, it would be advantageous to devise an instrument, which allows to be read out quickly and with high sensitivity. Due to the mentioned items the magnetic assay might be a possibility here.

  17. Scalloped electrodes for highly sensitive electrical measurements

    DEFF Research Database (Denmark)

    Vazquez Rodriguez, Patricia; Dimaki, Maria; Svendsen, Winnie Edith

    2011-01-01

    In this work we introduce a novel out-of-plane electrode with pronounced scalloped surface and high aspect ratio for electrical recordings of brain tissue in vitro, with the aim to reduce significantly the impedance of the measuring system. The profile and height of the structures is tailored by ...

  18. Probing High Temperature Superconductors with Magnetometry in Ultrahigh Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    Li, Lu [Univ. of Michigan, Ann Arbor, MI (United States)

    2017-07-26

    The objective of this research is to investigate the high-field magnetic properties of high temperature superconductors, materials that conduct electricity without loss. A technique known as high-resolution torque magnetometry that was developed to directly measure the magnetization of high temperature superconductors. This technique was implemented using the 65 Tesla pulsed magnetic field facility that is part of the National High Magnetic Field Laboratory at Los Alamos National Laboratory. This research addressed unanswered questions about the interplay between magnetism and superconductivity, determine the electronic structure of high temperature superconductors, and shed light on the mechanism of high temperature superconductivity and on potential applications of these materials in areas such as energy generation and power transmission. Further applications of the technology resolve the novel physical phenomena such as correlated topological insulators, and spin liquid state in quantum magnets.

  19. Highly linear, sensitive analog-to-digital converter

    Science.gov (United States)

    Cox, J.; Finley, W. R.

    1969-01-01

    Analog-to-digital converter converts 10 volt full scale input signal into 13 bit digital output. Advantages include high sensitivity, linearity, low quantitizing error, high resistance to mechanical shock and vibration loads, and temporary data storage capabilities.

  20. Magnetization and magnetostriction in highly magnetostrictive materials

    Energy Technology Data Exchange (ETDEWEB)

    Thoelke, Jennifer Beth [Iowa State Univ., Ames, IA (United States)

    1993-05-26

    The majority of this research has been in developing a model to describe the magnetostrictive properties of Terfenol-D, Tbsub>1-xDyxFey (x = 0.7-0.75 and y = 1.8--2.0), a rare earth-iron alloy which displays much promise for use in device applications. In the first chapter an introduction is given to the phenomena of magnetization and magnetostriction. The magnetic processes responsible for the observed magnetic properties of materials are explained. An overview is presented of the magnetic properties of rare earths, and more specifically the magnetic properties of Terfenol-D. In the second chapter, experimental results are presented on three composition of Tb< with x = 0.7, y= 1.9, 1.95, and x= 0.73, y= 1.95. The data were taken for various levels of prestress to show the effects of composition and microstructure on the magnetic and magnetostrictive properties of Terfenol-D. In the third chapter, a theoretical model is developed based on the rotation of magnetic domains. The model is used to explain the magnetic and magnetostrictive properties of Terfenol-D, including the observed negative strictions and large change in strain. The fourth chapter goes on to examine the magnetic properties of Terfenol-D along different crystallographic orientations. In the fifth chapter initial data are presented on the time dependence of magnetization in nickel.

  1. Current distribution evaluation of dye-sensitized solar cell using HTS-SQUID-based magnetic measurement system

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, Kenji, E-mail: Sakai-k@okayama-u.ac.jp; Tanaka, Kohei; Kiwa, Toshihiko; Tsukada, Keiji

    2016-11-15

    Highlights: • Current distribution and direction of dye-sensitized solar cell (DSSC) was measured. • Electrical current flowing in the indium tin oxide (ITO) glass substrate was uniform. • The distribution of electrical current depended on I–V characteristic. • Current direction changed when the performance of DSSC is low. - Abstract: The current flowing inside a dye-sensitized solar cell (DSSC) was measured using a high-temperature superconductor superconducting quantum interference device (HTS-SQUID)-based magnetic measurement system. Further, a new evaluation method of the DSSC, which is difficult to measure using the conventional method, was investigated to improve the characteristics of the DSSC. The tangential components of the magnetic field generated from the DSSC were measured using two HTS-SQUIDs, and the intensity and direction related to the electrical current were obtained by the measured magnetic field. The DSSCs prepared with different dyes and catalytic substances showed different current-intensity mapping. The current direction was different for the DSSC with low performance. In addition, the current flowing in the ITO layer of the ITO glass substrate was also measured and the results confirmed that it had uniform distribution. These results show that the current mapping and the direction of the electrical current depend on the internal factors of the DSSC, and the detection of the magnetic field distribution generated from it is expected to lead to its new evaluation method.

  2. Magnetic field effect in highly pure, highly fluorescent conjugated polymers

    Energy Technology Data Exchange (ETDEWEB)

    Graupner, W.; Sacher, M.; Graupner, M.; Zenz, C.; Grampp, G.; Hermetter, A.; Leising, G.

    1998-07-01

    The authors report on the magnetic field effect (MFE) on the photoluminescence in films of a highly fluorescent conjugated laddertype poly(paraphenylene) (LPPP). They observe no MFE for the pure material, however, the introduction of a very small content of chemical defects via photo-oxidation leads to a MFE proportional to the amount of defects. The chemically induced increase in MFE is correlated with a change in other properties of the LPPP films, such as photoluminescence emission and excitation spectra, transient photoluminescence and infrared spectra.

  3. Heterogeneous catalysis in highly sensitive microreactors

    DEFF Research Database (Denmark)

    Olsen, Jakob Lind

    oxygen surplus, is presented. The e_ect of pretreating the catalyst, CuZnO, in a mixture of H2 and CO before methanol synthesis, is presented. Transient increased methanol production is seen after pretreatment, with a maximum in the transient for a pretreatment with a one to one CO to H2 ratio...... of adsorbates readily converted to methanol as the source of the transient increase in methanol production, is eliminated. A study of mass selected ruthenium nanoparticles from a magnetron-sputter gas-aggregation source, deposited in microreactors, is presented. It is, shown that CO methanation can be measured....... The highly active state of the catalyst after pretreatment in a CO and H2 mixture is shown to have transient methanol synthesis capabilities at 60.. Estimates of the area of the catalytic surface, is obtained using formate temperature programmed desorption measurements. From these, the possibility...

  4. Highly sensitive fiber loop ringdown strain sensor with low temperature sensitivity

    Science.gov (United States)

    Ghimire, Maheshwar; Wang, Chuji

    2017-10-01

    We report a highly sensitive strain sensor with low temperature sensitivity based on the fiber loop ringdown technique. An innovative approach that employs a micro air-gap as the strain sensor head is described. The sensor has demonstrated the static strain sensitivity of 0.26 µs/µɛ, corresponding to the detection limit of 65 nɛ with the low temperature cross sensitivity of 37 nɛ/°C. This is the highest static strain sensitivity achieved without using a combination of fiber optic sensing components, such as fiber Bragg gratings or Fabry-Perot interferometers. Moreover, the sensor design allows the strain sensitivity and measuring range to be adjusted by changing the length of the sensor.

  5. Magnetic nanoparticles sensitize MCF-7 breast cancer cells to doxorubicin-induced apoptosis.

    Science.gov (United States)

    Aljarrah, Khaled; Mhaidat, Nizar M; Al-Akhras, M-Ali H; Aldaher, Ahmad N; Albiss, Ba; Aledealat, Khaled; Alsheyab, Fawzi M

    2012-04-25

    Resistance of breast cancer cells to the available chemotherapeutics is a major obstacle to successful treatment. Recent studies have shown that magnetic nanoparticles might have significant application in different medical fields including cancer treatment. The goal of this study is to verify the ability of magnetic nanoparticles to sensitize cancer cells to the clinically available chemotherapy. The role of iron oxide nanoparticles, static magnetic field, or a combination in the enhancement of the apoptotic potential of doxorubicin against the resistant breast cancer cells, MCF-7 was evaluated using the MTT assay and the propidium iodide method. In the present study, results revealed that pre-incubation of MCF-7 cells with iron oxide nanoparticles before the addition of doxorubicin did not enhance doxorubicin-induced growth inhibition. Pre-incubation of MCF-7 cells with iron oxide nanoparticles followed by a static magnetic field exposure significantly (P magnetic field was dose-dependent where the highest cytotoxicity was seen at 1 tesla. Further experiments revealed that the anti-proliferative effect of this treatment procedure is due to induction of apoptotic cell death. These results might point to the importance of combining magnetic nanoparticles with a static magnetic field in treatment of doxorubicin-refractory breast cancer cells.

  6. Pt-Decorated Magnetic Nanozymes for Facile and Sensitive Point-of-Care Bioassay.

    Science.gov (United States)

    Kim, Min Su; Kweon, Soon Ho; Cho, Seongyeon; An, Seong Soo A; Kim, Moon Il; Doh, Junsang; Lee, Jinwoo

    2017-10-11

    Development of facile and sensitive bioassays is important for many point-of-care applications. In this study, we fulfilled such demand by synthesizing Pt-decorated magnetic nanozymes and developing a bioassay based on unique properties of the newly synthesized nanozymes. Fe3O4-Pt/core-shell nanoparticles (MPt/CS NPs) with various compositions were synthesized and characterized. Fe3O4 NP itself is a good nanozyme with catalytic activity superior to that of natural enzymes, but catalytic activity can be further improved by incorporating Pt to the outer layers of the Fe3O4 NPs and building heterogeneous nanostructures. Magnetic properties of MPt/CS NPs enable magnetic enrichment of liquid samples, whereas catalytic properties of MPt/CS NPs allow signal amplification by enzyme-like reactions. By integrating MPt/CS NPs in lateral flow immunoassay strips, one of the widely used point-of-care bioassay devices, and harnessing magnetic and enzyme-like properties of MPt/CS NPs, an increase in sensitivity of two orders of magnitude was achieved compared to the sensitivity of conventional lateral flow immunoassay based on Au nanoparticles.

  7. Reducing Magnetic Noise of an Unmanned Aerial Vehicle for High-Quality Magnetic Surveys

    Directory of Open Access Journals (Sweden)

    Boris Sterligov

    2016-01-01

    Full Text Available The use of light and ultralight unmanned aerial vehicles (UAVs for magnetic data acquisition can be efficient for resolving multiple geological and engineering tasks including geological mapping, ore deposits’ prospecting, and pipelines’ monitoring. The accuracy of the aeromagnetic data acquired using UAV depends mainly on deviation noise of electric devices (engine, servos, etc.. The goal of this research is to develop a nonmagnetic unmanned aerial platform (NUAP for high-quality magnetic surveys. Considering parameters of regional and local magnetic survey, a fixed-wing UAV suits geological tasks better for plain area and copter type for hills and mountains. Analysis of the experimental magnetic anomalies produced by a serial light fixed-wing UAV and subsequent magnetic and aerodynamic modeling demonstrates a capacity of NUAP with internal combustion engine carrying an atomic magnetic sensor mounted on the UAV wings to facilitate a high-quality magnetic survey.

  8. High sensitivity probe absorption technique for time-of-flight ...

    Indian Academy of Sciences (India)

    We report on a phase-sensitive probe absorption technique with high sensitivity, capable of detecting a few hundred ultra-cold atoms in flight in an observation time of a few milliseconds. The large signal-to-noise ratio achieved is sufficient for reliable measurements on low intensity beams of cold atoms. We demonstrate the ...

  9. Non-foster impedance matching sensitivity of electrically small electric and magnetic spherical dipole antennas

    DEFF Research Database (Denmark)

    Yoon, Ick-Jae; Christensen, S.; Zhurbenko, Vitaliy

    2016-01-01

    The impedance bandwidth (BW) improvement property of a self-resonant folded spherical helix electric dipole and a spherical split ring (SSR) magnetic dipole is compared when a negative reactance element is loaded on the parasitic resonator of the antennas. They have the same electrical size of ka...... = 0.38 and both approach each lower Q-bound. It is found that the impedance characteristic reacts more sensitively to the loaded element for the SSR antenna due to the inherent two-times higher Q of the magnetic antenna. It is also found that a conventional non-Foster circuit composed of a series...

  10. Practical limits to the performance of magnetic bearings: Peak force, slew rate, and displacement sensitivity

    Science.gov (United States)

    Maslen, E.; Hermann, P.; Scott, M.; Humphris, R. R.

    1993-01-01

    Magnetic bearings are subject to performance limits which are quite different from those of conventional bearings. These are due in part to the inherent nonlinearity of the device and in part to its electrical nature. Three important nonideal behaviors are presented: peak force capacity, force slew rate limitation, and sensitivity to rotor motion at large displacements. The problem of identifying the dynamic requirements of a magnetic bearing when used to support a known structure subject to known loads is discussed in the context of these limitations. Several simple design tools result from this investigation.

  11. High temperature superconductor cable concepts for fusion magnets

    CERN Document Server

    AUTHOR|(CDS)2078397

    2013-01-01

    Three concepts of high temperature superconductor cables carrying kA currents (RACC, CORC and TSTC) are investigated, optimized and evaluated in the scope of their applicability as conductor in fusion magnets. The magnetic field and temperature dependence of the cables is measured; the thermal expansion and conductivity of structure, insulation and filling materials are investigated. High temperature superconductor winding packs for fusion magnets are calculated and compared with corresponding low temperature superconductor cases.

  12. Magnetic nanoparticles sensitize MCF-7 breast cancer cells to doxorubicin-induced apoptosis

    Directory of Open Access Journals (Sweden)

    Aljarrah Khaled

    2012-04-01

    Full Text Available Abstract Background Resistance of breast cancer cells to the available chemotherapeutics is a major obstacle to successful treatment. Recent studies have shown that magnetic nanoparticles might have significant application in different medical fields including cancer treatment. The goal of this study is to verify the ability of magnetic nanoparticles to sensitize cancer cells to the clinically available chemotherapy. Methods The role of iron oxide nanoparticles, static magnetic field, or a combination in the enhancement of the apoptotic potential of doxorubicin against the resistant breast cancer cells, MCF-7 was evaluated using the MTT assay and the propidium iodide method. Results In the present study, results revealed that pre-incubation of MCF-7 cells with iron oxide nanoparticles before the addition of doxorubicin did not enhance doxorubicin-induced growth inhibition. Pre-incubation of MCF-7 cells with iron oxide nanoparticles followed by a static magnetic field exposure significantly (P  Conclusions These results might point to the importance of combining magnetic nanoparticles with a static magnetic field in treatment of doxorubicin-refractory breast cancer cells.

  13. Highly sensitive humidity sensor based on graphene oxide foam

    Science.gov (United States)

    Zhang, Kai-Lun; Hou, Zhi-Ling; Zhang, Bao-Xun; Zhao, Quan-Liang

    2017-10-01

    Since sensitive humidity sensing is strongly desired, we present a highly sensitive humidity sensor fabricated from graphene oxide (GO) foam based on low-frequency dielectric properties. The GO foam shows humidity- and compression-dependent dielectric. Upon applying compression on GO foam, the humidity sensitivity increases and the maximum humidity sensitivity of dielectric loss is more than 12-fold higher than that of direct-current electrical conductivity. The highly sensitive humidity response originates from the generation of local conductive networks, which is the result of the connected isolated conductive regions by water cluster. Additionally, the dielectric properties of fabricated GO foam show a stable and repeatable humidity response, suggesting a carbon prototype with great potential in humidity sensors.

  14. Post-assembly magnetization of a 100 kW high speed permanent magnet rotor.

    Science.gov (United States)

    Lv, Yiliang; Wang, Guobin; Li, Liang

    2015-03-01

    A post-assembly magnetizing fixture has been designed and successfully used to magnetize the rotor of a 100 kW high speed permanent magnet synchronous motor. The rotor is a solid cylinder with outer diameter of 80 mm and total length of 515 mm. The permanent magnet material is samarium-cobalt (Sm2Co17) with saturation magnetizing field of 6 T. The mechanical stability of the magnetizing fixture has been studied as well as the general design methodology. The magnetizing coil is subdivided in order to reduce the electromagnetic force, and the coils are separately reinforced in different ways. The electromagnetic and structural optimization is performed by finite element analysis and verified by experiments.

  15. Transient magnetized plasma as an optical element for high power laser pulses

    Directory of Open Access Journals (Sweden)

    Nobuhiko Nakanii

    2015-02-01

    Full Text Available Underdense plasma produced in gas jets by low intensity laser prepulses in the presence of a static magnetic field, B∼0.3  T, is shown experimentally to become an optical element allowing steering of tightly focused high power femtosecond laser pulses within several degrees along with essential enhancement of pulse’s focusability. Strong laser prepulses form a density ramp perpendicularly to magnetic field direction and, owing to the light refraction, main laser pulses propagate along the magnetic field even if it is tilted from the laser axis. Electrons generated in the laser pulse wake are well collimated and follow in the direction of the magnetic field; their characteristics are measured to be not sensitive to the tilt of magnetic field up to angles ±5°.

  16. Effect of magnetic field inhomogeneity on ion cyclotron motion coherence at high magnetic field.

    Science.gov (United States)

    Vladimirov, Gleb; Kostyukevich, Yury; Hendrickson, Christopher L; Blakney, Greg T; Nikolaev, Eugene

    2015-01-01

    A three-dimensional code based on the particle-in-cell algorithm modified to account for the inhomogeneity of the magnetic field was applied to determine the effect of Z(1), Z(2), Z(3), Z(4), X, Y, ZX, ZY, XZ(2) YZ(2), XY and X(2)-Y(2) components of an orthogonal magnetic field expansion on ion motion during detection in an FT-ICR cell. Simulations were performed for magnetic field strengths of 4.7, 7, 14.5 and 21 Tesla, including experimentally determined magnetic field spatial distributions for existing 4.7 T and 14.5 T magnets. The effect of magnetic field inhomogeneity on ion cloud stabilization ("ion condensation") at high numbers of ions was investigated by direct simulations of individual ion trajectories. Z(1), Z(2), Z(3) and Z(4) components have the largest effect (especially Z(1)) on ion cloud stability. Higher magnetic field strength and lower m/z demand higher relative magnetic field homogeneity to maintain cloud coherence for a fixed time period. The dependence of mass resolving power upper limit on Z(1) inhomogeneity is evaluated for different magnetic fields and m/z. The results serve to set the homogeneity requirements for various orthogonal magnetic field components (shims) for future FT-ICR magnet design.

  17. Murine High Specificity/Sensitivity Competitive Europium Insulin Autoantibody Assay

    Science.gov (United States)

    Babaya, Naru; Liu, Edwin; Miao, DongMei; Li, Marcella; Yu, Liping

    2009-01-01

    Abstract Background Most insulin autoantibody assays for both human and animal models are in a radioassay format utilizing 125I-insulin, but despite the radioassay format international workshops have documented difficulty in standardization between laboratories. There is thus a need for simpler assay formats that do not utilize radioactivity, yet retain the high specificity and sensitivity of radioassays. Methods To establish an easier enzyme-linked immunosorbent assay (ELISA) for insulin autoantibodies of non-obese diabetic (NOD) mice, we used an ELISA format, competition with unlabeled insulin, europium-avidin, and time-resolved fluorescence detection (competitive europium insulin autoantibody assay). Results The competitive europium assay of insulin autoantibodies when applied to sera from NOD mice had high sensitivity and specificity (92% sensitivity, 100% specificity) compared to our standard insulin autoantibody radioassay (72% sensitivity, 100% specificity) in analyzing blind workshop sera. It is noteworthy that though the assay has extremely high sensitivity for murine insulin autoantibodies and utilizes human insulin as target autoantigen, human sera with high levels of insulin autoantibodies are not detected. Conclusions Our results clearly indicate that low levels of insulin autoantibodies can be detected in an ELISA-like format. Combining a europium-based ELISA with competition with fluid-phase autoantigen can be applicable to many autoantigens to achieve high specificity and sensitivity in an ELISA format. PMID:19344197

  18. High Field Magnetization of Tb Single Crystals

    DEFF Research Database (Denmark)

    Roeland, L. W.; Cock, G. J.; Lindgård, Per-Anker

    1975-01-01

    The magnetization of Tb single crystals was measured in magnetic fields to 34T along the hard direction at temperature of 1.8, 4.2, 65.5 and 77K, and along with easy direction at 4.2 and 77K. The data are compared with the results of a self-consistent spin wave calculation using a phenomenologica...... data on Tb. The conduction-electron polarization at zero field and temperature is (0.33+or-0.05) mu B/ion, and the susceptibility is greater than the Pauli susceptibility calculated from the band-structure.......The magnetization of Tb single crystals was measured in magnetic fields to 34T along the hard direction at temperature of 1.8, 4.2, 65.5 and 77K, and along with easy direction at 4.2 and 77K. The data are compared with the results of a self-consistent spin wave calculation using a phenomenological...... Hamiltonian including isotropic exchange interactions, effective single-ion anisotropy and magnetoelastic contributions. The parameters of this Hamiltonian were determined by fitting the theoretical results for the spin wave dispersion and energy gap as a function of temperature and magnetic field to existing...

  19. An integrated and sensitive detection platform for biosensing application based on Fe@Au magnetic nanoparticles as bead array carries.

    Science.gov (United States)

    Liu, Hongna; Li, Song; Liu, Lishang; Tian, Lan; He, Nongyue

    2010-12-15

    A sensitive and selective biosensor platform suited for SNP type using Fe@Au magnetic nanoparticles (GMNPs) to fabricate bead array is described. This new platform integrates the rapid binding kinetics of magnetic nanoparticles carriers, the multiplexing and encoding capabilities of chips, and tagged array. As a DNA sensor, the biotinylated single-stranded DNA was obtained by asymmetry PCR amplification, and then captured by GMNPs modified with streptavidin to form GMNP-ssDNA complexes without further purification. The complexes were immobilized on the slide to fabricate bead array through magnetic field. The bead array was hybridized with the corresponding allele-specific tag probes for each locus, and a pair of given universal detectors were applied to these markers analysis. Using bead array, all samples can be analyzed in one hybridization chamber which lowers the cost of the assay. Using universal tags, only a pair of universal dual-color probes labeled fluorophores was used for multiplex genotyping. Without the need of laborious and time-consuming elution, the experiment process was simple, reproducible and easy to handle. Two SNPs loci from 12 individual samples were discriminated using this platform and the results demonstrated that the expected scores and good discrimination were obtained between the two alleles from the two SNP loci. In summary, the integrated sensitive platform is adaptable and versatile, while offering a high-throughput capability needed for genome research and clinical applications. Copyright © 2010 Elsevier B.V. All rights reserved.

  20. High-aspect ratio magnetic nanocomposite polymer cilium

    Science.gov (United States)

    Rahbar, M.; Tseng, H. Y.; Gray, B. L.

    2014-03-01

    This paper presents a new fabrication technique to achieve ultra high-aspect ratio artificial cilia micro-patterned from flexible highly magnetic rare earth nanoparticle-doped polymers. We have developed a simple, inexpensive and scalable fabrication method to create cilia structures that can be actuated by miniature electromagnets, that are suitable to be used for lab-on-a chip (LOC) and micro-total-analysis-system (μ-TAS) applications such as mixers and flow-control elements. The magnetic cilia are fabricated and magnetically polarized directly in microfluidic channels or reaction chambers, allowing for easy integration with complex microfluidic systems. These cilia structures can be combined on a single chip with other microfluidic components employing the same permanently magnetic nano-composite polymer (MNCP), such as valves or pumps. Rare earth permanent magnetic powder, (Nd0.7Ce0.3)10.5Fe83.9B5.6, is used to dope polydimethylsiloxane (PDMS), resulting in a highly flexible M-NCP of much higher magnetization and remanence [1] than ferromagnetic polymers typically employed in magnetic microfluidics. Sacrificial poly(ethylene-glycol) (PEG) is used to mold the highly magnetic polymer into ultra high-aspect ratio artificial cilia. Cilia structures with aspect ratio exceeding 8:0.13 can be easily fabricated using this technique and are actuated using miniature electromagnets to achieve a high range of motion/vibration.

  1. Magnetic structures of erbium under high pressure

    DEFF Research Database (Denmark)

    Kawano, S.; Lebech, B.; Achiwa, N.

    1993-01-01

    Neutron diffraction studies of the magnetic structures of erbium metal at 4.5 K and 11.5 kbar hydrostatic pressure have revealed that the transition to a conical structure at low temperatures is suppressed and that the cycloidal structure, with modulation vector Q congruent-to (2/7 2pi/c)c persists...... between 4.5 K and approximately 50 K, where it tends to increase. The intensities of the magnetic satellites originating from higher-order harmonics of the c-axis-moment component observed at 4.5 K decrease slowly with increasing temperature, but persist up to approximately 60 K....

  2. Liquid Droplet Dynamics in Gravity Compensating High Magnetic Field

    Science.gov (United States)

    Bojarevics, V.; Easter, S.; Pericleous, K.

    2012-01-01

    Numerical models are used to investigate behavior of liquid droplets suspended in high DC magnetic fields of various configurations providing microgravity-like conditions. Using a DC field it is possible to create conditions with laminar viscosity and heat transfer to measure viscosity, surface tension, electrical and thermal conductivities, and heat capacity of a liquid sample. The oscillations in a high DC magnetic field are quite different for an electrically conducting droplet, like liquid silicon or metal. The droplet behavior in a high magnetic field is the subject of investigation in this paper. At the high values of magnetic field some oscillation modes are damped quickly, while others are modified with a considerable shift of the oscillating droplet frequencies and the damping constants from the non-magnetic case.

  3. High performance magnetocaloric perovskites for magnetic refrigeration

    DEFF Research Database (Denmark)

    Bahl, Christian R. H.; Velazquez, David; Nielsen, Kaspar K.

    2012-01-01

    We have applied mixed valance manganite perovskites as magnetocaloric materials in a magnetic refrigeration device. Relying on exact control of the composition and a technique to process the materials into single adjoined pieces, we have observed temperature spans above 9 K with two materials...

  4. Null space imaging: nonlinear magnetic encoding fields designed complementary to receiver coil sensitivities for improved acceleration in parallel imaging.

    Science.gov (United States)

    Tam, Leo K; Stockmann, Jason P; Galiana, Gigi; Constable, R Todd

    2012-10-01

    To increase image acquisition efficiency, we develop alternative gradient encoding strategies designed to provide spatial encoding complementary to the spatial encoding provided by the multiple receiver coil elements in parallel image acquisitions. Intuitively, complementary encoding is achieved when the magnetic field encoding gradients are designed to encode spatial information where receiver spatial encoding is ambiguous, for example, along sensitivity isocontours. Specifically, the method generates a basis set for the null space of the coil sensitivities with the singular value decomposition and calculates encoding fields from the null space vectors. A set of nonlinear gradients is used as projection imaging readout magnetic fields, replacing the conventional linear readout field and phase encoding. Multiple encoding fields are used as projections to capture the null space information, hence the term null space imaging. The method is compared to conventional Cartesian SENSitivity Encoding as evaluated by mean squared error and robustness to noise. Strategies for developments in the area of nonlinear encoding schemes are discussed. The null space imaging approach yields a parallel imaging method that provides high acceleration factors with a limited number of receiver coil array elements through increased time efficiency in spatial encoding. Copyright © 2011 Wiley Periodicals, Inc.

  5. Dual-stage trapped-flux magnet cryostat for measurements at high magnetic fields

    Science.gov (United States)

    Islam, Zahirul; Das, Ritesh K.; Weinstein, Roy

    2015-04-14

    A method and a dual-stage trapped-flux magnet cryostat apparatus are provided for implementing enhanced measurements at high magnetic fields. The dual-stage trapped-flux magnet cryostat system includes a trapped-flux magnet (TFM). A sample, for example, a single crystal, is adjustably positioned proximate to the surface of the TFM, using a translation stage such that the distance between the sample and the surface is selectively adjusted. A cryostat is provided with a first separate thermal stage provided for cooling the TFM and with a second separate thermal stage provided for cooling sample.

  6. Achieving sensitive, high-resolution laser spectroscopy at CRIS

    Energy Technology Data Exchange (ETDEWEB)

    Groote, R. P. de [Instituut voor Kern- en Stralingsfysica, KU Leuven (Belgium); Lynch, K. M., E-mail: kara.marie.lynch@cern.ch [EP Department, CERN, ISOLDE (Switzerland); Wilkins, S. G. [The University of Manchester, School of Physics and Astronomy (United Kingdom); Collaboration: the CRIS collaboration

    2017-11-15

    The Collinear Resonance Ionization Spectroscopy (CRIS) experiment, located at the ISOLDE facility, has recently performed high-resolution laser spectroscopy, with linewidths down to 20 MHz. In this article, we present the modifications to the beam line and the newly-installed laser systems that have made sensitive, high-resolution measurements possible. Highlights of recent experimental campaigns are presented.

  7. Achieving sensitive, high-resolution laser spectroscopy at CRIS

    Science.gov (United States)

    de Groote, R. P.; Lynch, K. M.; Wilkins, S. G.

    2017-11-01

    The Collinear Resonance Ionization Spectroscopy (CRIS) experiment, located at the ISOLDE facility, has recently performed high-resolution laser spectroscopy, with linewidths down to 20 MHz. In this article, we present the modifications to the beam line and the newly-installed laser systems that have made sensitive, high-resolution measurements possible. Highlights of recent experimental campaigns are presented.

  8. High-sensitivity troponin after running--a systematic review.

    Science.gov (United States)

    Vilela, E M; Bastos, J C C; Rodrigues, R P; Nunes, J P L

    2014-01-01

    A systematic review was carried out to study the pattern of high-sensitivity cardiac troponin release after running (search performed on PubMed, ISI Web of Knowledge and Scopus databases). A total of ten reports were identified as meeting the pre-specified criteria (eight using high-sensitivity troponin T and two using high-sensitivity troponin I). The papers were published between 2009 and 2013, amounting to a total of 479 participants under study. Eight reports provided data comparing post-running troponin levels with the 99th percentile reference value. A total number of 296 participants, out of 424, showed post-running high-sensitivity troponin values higher than the 99th percentile reference value (69.8%). In conclusion, using high-sensitivity cardiac troponin assays, studies have shown that elevated post-running values are seen in more than two-thirds of runners. Whether troponin release in this setting represents a fully reversible phenomenon is currently unknown; the effects of strenuous running on long-term health are also uncertain.

  9. Magnetic and structural phase transitions of MnBi under high magnetic fields

    Directory of Open Access Journals (Sweden)

    Keiichi Koyama, Yoshifuru Mitsui and Kazuo Watanabe

    2008-01-01

    Full Text Available High-field x-ray diffraction and magnetization measurements and differential thermal analysis (DTA were carried out for polycrystalline MnBi with an NiAs-type hexagonal structure to investigate its magnetic and structural phase transitions. The lattice parameter a rapidly decreases below the spin reorientation temperature TSR(=90 K in a zero magnetic field. The parameter c decreases gradually with decreasing temperature and exhibits an anomaly in the vicinity of TSR. By applying a magnetic field of 5 T, the parameter a increases by ~0.05% when Tmagnetic phase transition temperature from the ferromagnetic state to the paramagnetic state increases linearly at a rate of 2 KT−1 with increasing magnetic field up to 14 T.

  10. 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).

  11. Mechanical design of a high field common coil magnet

    Energy Technology Data Exchange (ETDEWEB)

    Caspi, S.; Chow, K.; Dietderich, D.; Gourlay, S.; Gupta, R.; McInturff, A.; Millos, G.; Scanlan, R.

    1999-03-18

    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.

  12. The Role of Superconducting Magnets for High Energy Physics

    CERN Document Server

    CERN. Geneva

    2012-01-01

    Superconducting Magnets have played a crucial role for the particle physics energy frontier. From Tevatron to LHC, passing through HERA and RHIC, they have defined the last 30 years of hadron colliders. The talk will review the successful projects and mention the reasons and learning from the ill-fated projects, Isabelle and SSC. Technology spin-off will be discussed, together with the development of the next generation magnets; the high field ones, aimed at passing the 10 Tesla frontier in collider quality magnets, and the fast cycled ones, aimed at enabling field ramp rates of 1 to 4 Tesla per second in synchrotron quality magnets.

  13. A High-Throughput SU-8Microfluidic Magnetic Bead Separator

    DEFF Research Database (Denmark)

    Bu, Minqiang; Christensen, T. B.; Smistrup, Kristian

    2007-01-01

    We present a novel microfluidic magnetic bead separator based on SU-8 fabrication technique for high through-put applications. The experimental results show that magnetic beads can be captured at an efficiency of 91 % and 54 % at flow rates of 1 mL/min and 4 mL/min, respectively. Integration of s...

  14. Conduction cooled high temperature superconducting dipole magnet for accelerator applications

    DEFF Research Database (Denmark)

    Zangenberg, N.; Nielsen, G.; Hauge, N.

    2012-01-01

    A 3T proof-of-principle dipole magnet for accelerator applications, based on 2nd generation high temperature superconducting tape was designed, built, and tested by a consortium under the lead of Danfysik. The magnet was designed to have a straight, circular bore with a good field region of radius...... = 25 mm, and a magnetic length of 250 mm. A total length of 2.5 km YBCO-based copper stabilized conductor supplied by SuperPower Inc., NY, USA, was isolated with 0.025 mm of epoxy and subsequently wound into 14 saddle coils and 4 racetrack coils with a cosine theta like configuration. The coils were......-liquid free operation of an HTS accelerator magnet was demonstrated. The cold mass support design permits magnet orientation under arbitrary angles. Careful choice of materials in terms of magnetic, heat conducting and mechanical properties resulted in a robust and compact solution which opens up...

  15. Magnetostructural transitions in a frustrated magnet at high fields.

    Science.gov (United States)

    Tsurkan, V; Zherlitsyn, S; Felea, V; Yasin, S; Skourski, Yu; Deisenhofer, J; von Nidda, H-A Krug; Lemmens, P; Wosnitza, J; Loidl, A

    2011-06-17

    Ultrasound and magnetization studies of bond-frustrated ZnCr(2)S(4) spinel are performed in static magnetic fields up to 18 T and in pulsed fields up to 62 T. At temperatures below the antiferromagnetic transition at T(N1)≈14  K, the sound velocity as a function of the magnetic field reveals a sequence of steps followed by plateaus indicating a succession of crystallographic structures with constant stiffness. At the same time, the magnetization evolves continuously with a field up to full magnetic polarization without any plateaus in contrast to geometrically frustrated chromium oxide spinels. The observed high-field magnetostructural states are discussed within a H-T phase diagram taking into account the field and temperature evolution of three coexisting spin structures and subsequent lattice transformations induced by the magnetic field.

  16. High accuracy magnetic field mapping of the LEP spectrometer magnet

    CERN Document Server

    Roncarolo, F

    2000-01-01

    The Large Electron Positron accelerator (LEP) is a storage ring which has been operated since 1989 at the European Laboratory for Particle Physics (CERN), located in the Geneva area. It is intended to experimentally verify the Standard Model theory and in particular to detect with high accuracy the mass of the electro-weak force bosons. Electrons and positrons are accelerated inside the LEP ring in opposite directions and forced to collide at four locations, once they reach an energy high enough for the experimental purposes. During head-to-head collisions the leptons loose all their energy and a huge amount of energy is concentrated in a small region. In this condition the energy is quickly converted in other particles which tend to go away from the interaction point. The higher the energy of the leptons before the collisions, the higher the mass of the particles that can escape. At LEP four large experimental detectors are accommodated. All detectors are multi purpose detectors covering a solid angle of alm...

  17. High-sensitivity Compton imaging with position-sensitive Si and Ge detectors

    Energy Technology Data Exchange (ETDEWEB)

    Vetter, K. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States)], E-mail: kvetter@llnl.gov; Burks, M.; Cork, C.; Cunningham, M.; Chivers, D.; Hull, E. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Krings, T. [Institut fuer Kernphysik, Forschungszentrum Juelich, 52425 Juelich (Germany); Manini, H.; Mihailescu, L.; Nelson, K. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Protic, D. [Institut fuer Kernphysik, Forschungszentrum Juelich, 52425 Juelich (Germany); Valentine, J.; Wright, D. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States)

    2007-08-21

    We report on the development of high-sensitivity and compact Compton imaging systems built of large and position-sensitive Si(Li) and HPGe detectors. The primary goal of this effort is to provide improved capabilities in the passive detection of nuclear materials for homeland security. Our detectors are implemented in double-sided strip configuration, which-along with digital signal processing-provides energies and three-dimensional position information of individual {gamma}-ray interactions. {gamma}-Ray tracking algorithms then determine the scattering sequence of the {gamma}-ray, which in turn allows us-employing the Compton scattering formula-to reconstruct a cone of possible incident angles and ultimately an image. This Compton imaging concept enables large-field-of-view {gamma}-ray imaging without the use of a heavy collimator or aperture. The intrinsically high-energy resolution of the detectors used, the excellent position resolution we have demonstrated, both combined with the high efficiency of large-volume detectors is the basis for high Compton imaging sensitivity. These capabilities are being developed to identify and localize potential threat sources and to potentially increase the sensitivity in detecting weak sources out of the midst of natural, medical, or commercial sources. {gamma}-ray imaging provides a new degree of freedom to distinguish between spatial and temporal background fluctuations and compact threat sources.

  18. Flatland Electrons in High Magnetic Fields

    Science.gov (United States)

    Shayegan, M.

    This paper provides a review of recent developments in the physics of two-dimensional carrier systems in perpendicular magnetic fields. The emphasis is on many-body phenomena in very clean GaAs/AlGaAs heterostructures, probed via magnetotransport measurements. Topics that are discussed include the integer and fractional quantum Hall effects, Wigner crystallization, composite Fermions, Skyrmions, stripe and bubble phases in single layer systems, and electron-hole pairing and Bose-Einstein condensation in interacting bilayer systems.

  19. Advanced measurements and techniques in high magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, L.J.; Rickel, D.G. [Los Alamos National Lab., NM (United States); Lacerda, A.H. [Florida State Univ., Tallahassee, FL (United States); Kim, Y. [Northeastern Univ., Boston, MA (United States)

    1997-07-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). High magnetic fields present a unique environment for studying the electronic structure of materials. Two classes of materials were chosen for experiments at the national high Magnetic Field Laboratory at Los Alamos: highly correlated electron systems and semiconductors. Magnetotransport and thermodynamic experiments were performed on the renormalized ground states of highly correlated electron systems (such as heavy fermion materials and Kondo insulators) in the presence of magnetic fields that are large enough to disrupt the many-body correlations. A variety of optical measurements in high magnetic fields were performed on semiconductor heterostructures including GaAs/AlGaAs single heterojunctions (HEMT structure), coupled double quantum wells (CDQW), asymmetric coupled double quantum wells (ACDQW), multiple quantum wells and a CdTe single crystal thin film.

  20. Status of high temperature superconductor development for accelerator magnets

    Science.gov (United States)

    Hirabayashi, H.

    1995-01-01

    High temperature superconductors are still under development for various applications. As far as conductors for magnets are concerned, the development has just been started. Small coils wound by silver sheathed Bi-2212 and Bi-2223 oxide conductors have been reported by a few authors. Essential properties of high T(sub c) superconductors like pinning force, coherent length, intergrain coupling, weak link, thermal property, AC loss and mechanical strength are still not sufficiently understandable. In this talk, a review is given with comparison between the present achievement and the final requirement for high T(sub c) superconductors, which could be particularly used in accelerator magnets. Discussions on how to develop high T(sub c) superconductors for accelerator magnets are included with key parameters of essential properties. A proposal of how to make a prototype accelerator magnet with high T(sub c) superconductors with prospect for future development is also given.

  1. High-sensitivity, high-speed continuous imaging system

    Science.gov (United States)

    Watson, Scott A; Bender, III, Howard A

    2014-11-18

    A continuous imaging system for recording low levels of light typically extending over small distances with high-frame rates and with a large number of frames is described. Photodiode pixels disposed in an array having a chosen geometry, each pixel having a dedicated amplifier, analog-to-digital convertor, and memory, provide parallel operation of the system. When combined with a plurality of scintillators responsive to a selected source of radiation, in a scintillator array, the light from each scintillator being directed to a single corresponding photodiode in close proximity or lens-coupled thereto, embodiments of the present imaging system may provide images of x-ray, gamma ray, proton, and neutron sources with high efficiency.

  2. Replacing critical rare earth materials in high energy density magnets

    Science.gov (United States)

    McCallum, R. William

    2012-02-01

    High energy density permanent magnets are crucial to the design of internal permanent magnet motors (IPM) for hybride and electric vehicles and direct drive wind generators. Current motor designs use rare earth permanent magnets which easily meet the performance goals, however, the rising concerns over cost and foreign control of the current supply of rare earth resources has motivated a search for non-rare earth based permanent magnets alloys with performance metrics which allow the design of permanent magnet motors and generators without rare earth magnets. This talk will discuss the state of non-rare-earth permanent magnets and efforts to both improve the current materials and find new materials. These efforts combine first principles calculations and meso-scale magnetic modeling with advance characterization and synthesis techniques in order to advance the state of the art in non rare earth permanent magnets. The use of genetic algorithms in first principle structural calculations, combinatorial synthesis in the experimental search for materials, atom probe microscopy to characterize grain boundaries on the atomic level, and other state of the art techniques will be discussed. In addition the possibility of replacing critical rare earth elements with the most abundant rare earth Ce will be discussed.

  3. Quantifying Magnetic Sensitivity of Radical Pair Based Compass by Quantum Fisher Information.

    Science.gov (United States)

    Guo, Li-Sha; Xu, Bao-Ming; Zou, Jian; Shao, Bin

    2017-07-19

    The radical pair (RP) based compass is considered as one of the principal models of avian magnetoreception. Different from the conventional approach where the sensitivity of RP based compass is described by the singlet yield, we introduce the quantum Fisher information (QFI), which represents the maximum information about the magnetic field's direction extracted from the RP state, to quantify the sensitivity of RP based compass. The consistency between our results and experimental observations suggests that the QFI may serve as a measure to describe the sensitivity of RP based compass. Besides, within the framework of quantum metrology, we give two specific possible measurement schemes and find that the conventional singlet yield is corresponding to the measurement of total angular momentum. Moreover, we show that the measurement of fluctuation of the total magnetic moment is much more accurate than the singlet yield measurement, and is close to the optimal measurement scheme. Finally, the effects of entanglement and decoherence are also discussed in the spirit of our approach.

  4. Makeup and uses of a basic magnet laboratory for characterizing high-temperature permanent magnets

    Science.gov (United States)

    Niedra, Janis M.; Schwarze, Gene E.

    1991-01-01

    A set of instrumentation for making basic magnetic measurements was assembled in order to characterize high intrinsic coercivity, rare earth permanent magnets with respect to short term demagnetization resistance and long term aging at temperatures up to 300 C. The major specialized components of this set consist of a 13 T peak field, capacitor discharge pulse magnetizer; a 10 in. pole size, variable gap electromagnet; a temperature controlled oven equipped with iron cobalt pole piece extensions and a removable paddle that carries the magnetization and field sensing coils; associated electronic integrators; and sensor standards for field intensity H and magnetic moment M calibration. A 1 cm cubic magnet sample, carried by the paddle, fits snugly between the pole piece extensions within the electrically heated aluminum oven, where fields up to 3.2 T can be applied by the electromagnet at temperatures up to 300 C. A sample set of demagnetization data for the high energy Sm2Co17 type of magnet is given for temperatures up to 300 C. These data are reduced to the temperature dependence of the M-H knee field and of the field for a given magnetic induction swing, and they are interpreted to show the limits of safe operation.

  5. Magnetic superelevation design of Halbach permanent magnet guideway for high-temperature superconducting maglev

    Science.gov (United States)

    Lei, Wuyang; Qian, Nan; Zheng, Jun; Huang, Huan; Zhang, Ya; Deng, Zigang

    2017-07-01

    To improve the curve negotiating ability of high-temperature superconducting (HTS) maglev system, a special structure of magnetic superelevation for double-pole Halbach permanent magnet guideway (PMG) was designed. The most significant feature of this design is the asymmetrical PMG that forms a slanting magnetic field without affecting the smoothness of the PMG surface. When HTS maglev vehicle runs through curves with magnetic superelevation, the vehicle will slant due to asymmetry in magnetic field and the flux-pinning effect of onboard HTS bulks. At the same time, one component of the levitation force provides a part of the centripetal force that reduces lateral acceleration of the vehicle and thus enhances its curve negotiating ability. Furthermore, the slant angle of magnetic superelevation can be adjusted by changing the materials and the thickness of the added permanent magnets. This magnetic superelevation method, together with orographic uplift, can be applied to different requirements of PMG designs. Besides, the applicability of this method would benefit future development of high-speed HTS maglev system.

  6. Magnetic properties of sintered high energy sm-co and nd-fe-b magnets

    Directory of Open Access Journals (Sweden)

    Talijan Nadežda M.

    2006-01-01

    Full Text Available Magnetic properties of permanent magnetic materials based on intermetallic compounds of Sm-Co and Nd-Fe-B are in direct dependence on the microstructure. In the first part of this paper, having in mind the importance of the regime of sintering and heat treatment to obtain the optimal magnetic structure, yet another approach in defining the most adequate technological parameters of the sintering process for applied heat treatment conditions was made. The goal of these investigations was to use the correlation that exists between sintering conditions (temperature and time and intensity of the diffraction peak of the (111 plane of the SmCo5 phase to optimize. In the second part a brief overview of high energy magnetic materials based on Nd-Fe-B is presented with special emphasis to the current research and development of high remanent nanocomposite magnetic materials based on Nd-Fe-B alloys with a reduced Nd content. Part of experimental results gained during research of the sintering process of SmCo5 magnetic materials were realized and published earlier. The scientific meeting devoted to the 60th anniversary of Frankel’s theory of sintering was an opportunity to show once more the importance and role of sintering in optimization of the magnetic microstructure of sintered Sm Co5 magnetic materials.

  7. Conceptual Design of the 45 T Hybrid Magnet at the Nijmegen High Field Magnet Laboratory

    CERN Document Server

    Wiegers, SAJ; Bird, M D; Rook, J; Perenboom, J A A J; Wiegers, S A J; Bonito-Oliva, A; den Ouden, A

    2010-01-01

    A 45 T Hybrid Magnet System is being developed at the Nijmegen High Field Magnet Laboratory as part of the Nijmegen Center for Advanced Spectroscopy. The 45 T Hybrid Magnet System will be used in combination with far-infra-red light produced by a Free Electron Laser under construction directly adjacent to the High Field Magnet Laboratory. The superconducting outsert magnet will consist of three CICC coils wound on a single coil form, using Nb3Sn strands. A test program for strand and cable qualification is underway. The CICC will carry 13 kA and the coils will produce 12 T on axis field in a 600 mm warm bore. The nominal operating temperature will be 4.5 K maintained with forced-flow supercritical helium. The insert magnet will produce 33 T at 40 kA in a 32 mm bore consuming 20 MW, and will consist of four coils. The insert magnet will be galvanically and mechanically isolated from the outsert magnet. Complete system availability for users is expected in 2014. In this paper we will report on the conceptual de...

  8. Magnetoelectric Transverse Gradient Sensor with High Detection Sensitivity and Low Gradient Noise.

    Science.gov (United States)

    Zhang, Mingji; Or, Siu Wing

    2017-10-25

    We report, theoretically and experimentally, the realization of a high detection performance in a novel magnetoelectric (ME) transverse gradient sensor based on the large ME effect and the magnetic field gradient (MFG) technique in a pair of magnetically-biased, electrically-shielded, and mechanically-enclosed ME composites having a transverse orientation and an axial separation. The output voltage of the gradient sensor is directly obtained from the transverse MFG-induced difference in ME voltage between the two ME composites and is calibrated against transverse MFGs to give a high detection sensitivity of 0.4-30.6 V/(T/m), a strong common-mode magnetic field noise rejection rate of noise of 0.16-620 nT/m/ Hz in a broad frequency range of 1 Hz-170 kHz under a small baseline of 35 mm. An analysis of experimental gradient noise spectra obtained in a magnetically-unshielded laboratory environment reveals the domination of the pink (1/ f ) noise, dielectric loss noise, and power-frequency noise below 3 kHz, in addition to the circuit noise above 3 kHz, in the gradient sensor. The high detection performance, together with the added merit of passive and direct ME conversion by the large ME effect in the ME composites, makes the gradient sensor suitable for the passive, direct, and broadband detection of transverse MFGs.

  9. Large pi-aromatic molecules as potential sensitizers for highly efficient dye-sensitized solar cells.

    Science.gov (United States)

    Imahori, Hiroshi; Umeyama, Tomokazu; Ito, Seigo

    2009-11-17

    Recently, dye-sensitized solar cells have attracted much attention relevant to global environmental issues. Thus far, ruthenium(II) bipyridyl complexes have proven to be the most efficient TiO(2) sensitizers in dye-sensitized solar cells. However, a gradual increment in the highest power conversion efficiency has been recognized in the past decade. More importantly, considering that ruthenium is a rare metal, novel dyes without metal or using inexpensive metal are desirable for highly efficient dye-sensitized solar cells. Large pi-aromatic molecules, such as porphyrins, phthalocyanines, and perylenes, are important classes of potential sensitizers for highly efficient dye-sensitized solar cells, owing to their photostability and high light-harvesting capabilities that can allow applications in thinner, low-cost dye-sensitized solar cells. Porphyrins possess an intense Soret band at 400 nm and moderate Q bands at 600 nm. Nevertheless, the poor light-harvesting properties relative to the ruthenium complexes have limited the cell performance of porphyrin-sensitized TiO(2) cells. Elongation of the pi conjugation and loss of symmetry in porphyrins cause broadening and a red shift of the absorption bands together with an increasing intensity of the Q bands relative to that of the Soret band. On the basis of the strategy, the cell performance of porphyrin-sensitized solar cells has been improved intensively by the enhanced light absorption. Actually, some push-pull-type porphyrins have disclosed a remarkably high power conversion efficiency (6-7%) that was close to that of the ruthenium complexes. Phthalocyanines exhibit strong absorption around 300 and 700 nm and redox features that are similar to porphyrins. Moreover, phthalocyanines are transparent over a large region of the visible spectrum, thereby enabling the possibility of using them as "photovoltaic windows". However, the cell performance was poor, owing to strong aggregation and lack of directionality in the

  10. Inorganic Nanostructured High-Temperature Magnet Wires Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This project will develop a high-temperature tolerant electrically-insulating coating for magnet wires. The Phase I program will result in a flexible, inorganic...

  11. Radiation Shielding Utilizing A High Temperature Superconducting Magnet Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This project aims to leverage near-term high-temperature superconducting technologies to assess applicability of magnetic shielding for protecting against exposure...

  12. Self-propagating high temperature synthesis and magnetic ...

    Indian Academy of Sciences (India)

    Unknown

    , microstructure and magnetic properties of the combustion products. The effect of ... productivity, low external energy consumption, short synthesis time, simple facility and high quality of the products. Although there have been many attempts to.

  13. Performance of terahertz metamaterials as high-sensitivity sensor

    Science.gov (United States)

    He, Yanan; Zhang, Bo; Shen, Jingling

    2017-09-01

    A high-sensitivity sensor based on the resonant transmission characteristics of terahertz (THz) metamaterials was investigated, with the proposal and fabrication of rectangular bar arrays of THz metamaterials exhibiting a period of 180 μm on a 25 μm thick flexible polyimide. Varying the size of the metamaterial structure revealed that the length of the rectangular unit modulated the resonant frequency, which was verified by both experiment and simulation. The sensing characteristics upon varying the surrounding media in the sample were tested by simulation and experiment. Changing the surrounding medium from that of air to that of alcohol or oil produced resonant frequency redshifts of 80 GHz or 150 GHz, respectively, which indicates that the sensor possessed a high sensitivity of 667 GHz per unit of refractive index. Finally, the influence of the sample substrate thickness on the sensor sensitivity was investigated by simulation. It may be a reference for future sensor design.

  14. A highly sensitive method for quantification of iohexol

    DEFF Research Database (Denmark)

    Schulz, A.; Boeringer, F.; Swifka, J.

    2014-01-01

    lohexol (1-N,3-N-bis(2,3-dihydroxypropyl)-5-IN-(2,3-dihydroxypropyl) acetamide-2,4,6-triiodobenzene1,3-dicarboxamide) is used for accurate determination of the glomerular filtration rate (GFR) in chronic kidney disease (CKD) patients. However, high iohexol amounts might lead to adverse effects in...... in organisms. In order to minimize the iohexol dosage required for the GFR determination in humans, the development of a sensitive quantification method is essential. Therefore, the objective of our preclinical study was to establish and validate a simple and robust liquid......-spectrometry based method has been proved to be sensitive, selective and suitable for the quantification of iohexol in serum. Due to high sensitivity of this novel method the iohexol application dose as well as the sampling time in the clinical routine could be reduced in the future in order to further minimize side...

  15. High magnetic fields in couplers of x-band acceleratingstructures

    CERN Document Server

    Dolgashev, V A

    2003-01-01

    Recent high power tests of x-band accelerating structures at SLAC have shown that Coupler models were matched with an automated procedure that uses the commercial To reduce the high magnetic fields new couplers were designed. These couplers and typical results for couplers with sharp and rounded irises are discussed in code HFSS. This matching procedure is based on calculation of reflection from have 3 mm radius waveguide-to-coupler-cell iris and maximum magnetic field below is consistent with a model of pulsed heating due to high magnetic fields. The magnetic fields, 3D electrodynamics models of the couplers were built and matched. matching, the magnetic and electric fields in the couplers were calculated for typical observed damage is located in the region of high magnetic fields. To calculate these on sharp (approx 80 micron radius) edges of the waveguide-to-coupler-cell irises. For operation parameters. Highest magnetic fields on the order of 1 MA/m were found some input couplers, electric fields on these...

  16. Magnetic tweezers with high permeability electromagnets for fast actuation of magnetic beads.

    Science.gov (United States)

    Chen, La; Offenhäusser, Andreas; Krause, Hans-Joachim

    2015-04-01

    As a powerful and versatile scientific instrument, magnetic tweezers have been widely used in biophysical research areas, such as mechanical cell properties and single molecule manipulation. If one wants to steer bead position, the nonlinearity of magnetic properties and the strong position dependence of the magnetic field in most magnetic tweezers lead to quite a challenge in their control. In this article, we report multi-pole electromagnetic tweezers with high permeability cores yielding high force output, good maneuverability, and flexible design. For modeling, we adopted a piece-wise linear dependence of magnetization on field to characterize the magnetic beads. We implemented a bi-linear interpolation of magnetic field in the work space, based on a lookup table obtained from finite element simulation. The electronics and software were custom-made to achieve high performance. In addition, the effects of dimension and defect on structure of magnetic tips also were inspected. In a workspace with size of 0.1 × 0.1 mm(2), a force of up to 400 pN can be applied on a 2.8 μm superparamagnetic bead in any direction within the plane. Because the magnetic particle is always pulled towards a tip, the pulling forces from the pole tips have to be well balanced in order to achieve control of the particle's position. Active video tracking based feedback control is implemented, which is able to work at a speed of up to 1 kHz, yielding good maneuverability of the magnetic beads.

  17. Magnetic tweezers with high permeability electromagnets for fast actuation of magnetic beads

    Energy Technology Data Exchange (ETDEWEB)

    Chen, La; Offenhäusser, Andreas; Krause, Hans-Joachim [Institute of Bioelectronics (ICS-8/PGI-8), Forschungszentrum Jülich GmbH, 52425 Jülich (Germany)

    2015-04-15

    As a powerful and versatile scientific instrument, magnetic tweezers have been widely used in biophysical research areas, such as mechanical cell properties and single molecule manipulation. If one wants to steer bead position, the nonlinearity of magnetic properties and the strong position dependence of the magnetic field in most magnetic tweezers lead to quite a challenge in their control. In this article, we report multi-pole electromagnetic tweezers with high permeability cores yielding high force output, good maneuverability, and flexible design. For modeling, we adopted a piece-wise linear dependence of magnetization on field to characterize the magnetic beads. We implemented a bi-linear interpolation of magnetic field in the work space, based on a lookup table obtained from finite element simulation. The electronics and software were custom-made to achieve high performance. In addition, the effects of dimension and defect on structure of magnetic tips also were inspected. In a workspace with size of 0.1 × 0.1 mm{sup 2}, a force of up to 400 pN can be applied on a 2.8 μm superparamagnetic bead in any direction within the plane. Because the magnetic particle is always pulled towards a tip, the pulling forces from the pole tips have to be well balanced in order to achieve control of the particle’s position. Active video tracking based feedback control is implemented, which is able to work at a speed of up to 1 kHz, yielding good maneuverability of the magnetic beads.

  18. Novel Josephson circuit elements for high magnetic field parity detection

    Science.gov (United States)

    Cassidy, Maja

    Evidence for Majorana modes in semiconductor nanowires to date has relied on DC transport measurements that probe their zero-energy characteristics. However, in order to unambiguously demonstrate the non-Abelian nature of Majoranas, it is necessary to braid them and measure their parity. Superconducting transmon qubits have been shown to be sensitive parity detectors, however traditional designs are incompatible with the strong magnetic fields required for the creation of Majoranas in nanowires. In this talk I will discuss our development of novel superconducting circuit elements such as CPW resonators, tunnel junctions, transmon qubits and on chjp microwave sources that survive magnetic fields in excess of 1T.

  19. Low temperature superconductor and aligned high temperature superconductor magnetic dipole system and method for producing high magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Ramesh; Scanlan, Ronald; Ghosh, Arup K.; Weggel, Robert J.; Palmer, Robert; Anerella, Michael D.; Schmalzle, Jesse

    2017-10-17

    A dipole-magnet system and method for producing high-magnetic-fields, including an open-region located in a radially-central-region to allow particle-beam transport and other uses, low-temperature-superconducting-coils comprised of low-temperature-superconducting-wire located in radially-outward-regions to generate high magnetic-fields, high-temperature-superconducting-coils comprised of high-temperature-superconducting-tape located in radially-inward-regions to generate even higher magnetic-fields and to reduce erroneous fields, support-structures to support the coils against large Lorentz-forces, a liquid-helium-system to cool the coils, and electrical-contacts to allow electric-current into and out of the coils. The high-temperature-superconducting-tape may be comprised of bismuth-strontium-calcium-copper-oxide or rare-earth-metal, barium-copper-oxide (ReBCO) where the rare-earth-metal may be yttrium, samarium, neodymium, or gadolinium. Advantageously, alignment of the large-dimension of the rectangular-cross-section or curved-cross-section of the high-temperature-superconducting-tape with the high-magnetic-field minimizes unwanted erroneous magnetic fields. Alignment may be accomplished by proper positioning, tilting the high-temperature-superconducting-coils, forming the high-temperature-superconducting-coils into a curved-cross-section, placing nonconducting wedge-shaped-material between windings, placing nonconducting curved-and-wedge-shaped-material between windings, or by a combination of these techniques.

  20. High-resolution magnetic field imaging with a nitrogen-vacancy diamond sensor integrated with a photonic-crystal fiber.

    Science.gov (United States)

    Fedotov, I V; Blakley, S M; Serebryannikov, E E; Hemmer, P; Scully, M O; Zheltikov, A M

    2016-02-01

    We demonstrate high-resolution magnetic field imaging with a scanning fiber-optic probe which couples nitrogen-vacancy (NV) centers in diamond to a high-numerical-aperture photonic-crystal fiber integrated with a two-wire microwave transmission line. Magnetic resonance excitation of NV centers driven by the microwave field is read out through optical interrogation through the photonic-crystal fiber to enable high-speed, high-sensitivity magnetic field imaging with sub 30 μm spatial resolution.

  1. Portable High Sensitivity and High Resolution Sensor to Determine Oxygen Purity Levels Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this Phase I STTR project is to develop a highly sensitive oxygen (O2) sensor, with high accuracy and precision, to determine purity levels of high...

  2. Survey of Processing Methods for High Strength High Conductivity Wires for High Field Magnet Applications

    Energy Technology Data Exchange (ETDEWEB)

    Han, K.; Embury, J.D.

    1998-10-01

    This paper will deal with the basic concepts of attaining combination of high strength and high conductivity in pure materials, in-situ composites and macrocomposites. It will survey current attainments, and outline where some future developments may lie in developing wire products that are close to the theoretical strength of future magnet applications.

  3. Aluminum nano-cantilevers for high sensitivity mass sensors

    DEFF Research Database (Denmark)

    Davis, Zachary James; Boisen, Anja

    2005-01-01

    We have fabricated Al nano-cantilevers using a very simple one mask contact UV lithography technique with lateral dimensions under 500 nm and vertical dimensions of approximately 100 nm. These devices are demonstrated as highly sensitive mass sensors by measuring their dynamic properties. Further...

  4. Sensitive high performance liquid chromatographic method for the ...

    African Journals Online (AJOL)

    A new simple, sensitive, cost-effective and reproducible high performance liquid chromatographic (HPLC) method for the determination of proguanil (PG) and its metabolites, cycloguanil (CG) and 4-chlorophenylbiguanide (4-CPB) in urine and plasma is described. The extraction procedure is a simple three-step process ...

  5. High-sensitivity C-reactive protein, lipid profile, malondialdehyde ...

    African Journals Online (AJOL)

    High-sensitivity C-reactive protein, lipid profile, malondialdehyde and total antioxidant capacity in psoriasis. ... Abstract. Psoriasis is a chronic inflammatory skin disease characterized by epidermal hyperproliferation and lymphocytic infiltration. The ongoing inflammatory process in psoriasis affects the arterial wall promoting ...

  6. Performance studies on high pressure 1-D position sensitive ...

    Indian Academy of Sciences (India)

    Performance studies on high pressure 1-D position sensitive neutron detectors. S S DESAI and A M SHAIKH∗. Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India. *Corresponding author. E-mail: shaikham@barc.gov.in. Abstract. The powder diffractometer and Hi-Q diffractometer at ...

  7. Experimental Contribution to High-Precision Characterization of Magnetic Forces in Active Magnetic Bearings

    DEFF Research Database (Denmark)

    Kjølhede, Klaus; Santos, Ilmar

    2007-01-01

    Parameter identification procedures and model validation are major steps toward intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model...... contribution of the work is the characterization of magnetic forces by using two different experimental approaches. Such approaches are investigated and described in detail. A special test rig is designed where the four pole AMB is able to generate forces up to 1900 N. The high-precision characterization...... of the magnetic forces is conducted using different experimental tests: (i) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor (ii) by measuring the input current and bearing...

  8. Application of high temperature superconductors to high-gradient magnetic separation

    Energy Technology Data Exchange (ETDEWEB)

    Daugherty, M.A.; Prenger, F.C.; Hill, D.D.; Daney, D.E.; Worl, L.W.; Schake, A.R.; Padilla, D.D.

    1994-06-01

    High Gradient Magnetic Separation (HGMS) is a powerful technique which can be used to separate widely dispersed contaminants from a host material, This technology can separate magnetic solids from other solids, liquids or gases. As the name implies HGMS uses large magnetic field gradients to separate ferromagnetic and paramagnetic particles. HGMS separators usually consist of a high-field solenoid magnet, the bore of which contains a fine-structured, ferromagnetic matrix material. The matrix material locally distorts the magnetic field and creates large field gradients in the vicinity of the matrix elements. These elements then become trapping sites for magnetic particles and are the basis for the magnetic separation. In this paper we discuss the design and construction of a prototype HGMS unit using a magnet made with high temperature superconductors (HTS). The prototype consists of an outer vacuum vessel which contains the HTS solenoid magnet The magnet is surrounded by a thermal radiation shield and multilayer insulation (MLI) blankets. The magnet, thermal shield and current leads all operate in a vacuum and are cooled by a cryocooler. High temperature superconducting current leads are used to reduce the heat leak from the ambient environment to the HTS magnet.

  9. Highly sensitive detection using microring resonator and nanopores

    Science.gov (United States)

    Bougot-Robin, K.; Hoste, J. W.; Le Thomas, N.; Bienstman, P.; Edel, J. B.

    2016-04-01

    One of the most significant challenges facing physical and biological scientists is the accurate detection and identification of single molecules in free-solution environments. The ability to perform such sensitive and selective measurements opens new avenues for a large number of applications in biological, medical and chemical analysis, where small sample volumes and low analyte concentrations are the norm. Access to information at the single or few molecules scale is rendered possible by a fine combination of recent advances in technologies. We propose a novel detection method that combines highly sensitive label-free resonant sensing obtained with high-Q microcavities and position control in nanoscale pores (nanopores). In addition to be label-free and highly sensitive, our technique is immobilization free and does not rely on surface biochemistry to bind probes on a chip. This is a significant advantage, both in term of biology uncertainties and fewer biological preparation steps. Through combination of high-Q photonic structures with translocation through nanopore at the end of a pipette, or through a solid-state membrane, we believe significant advances can be achieved in the field of biosensing. Silicon microrings are highly advantageous in term of sensitivity, multiplexing, and microfabrication and are chosen for this study. In term of nanopores, we both consider nanopore at the end of a nanopipette, with the pore being approach from the pipette with nanoprecise mechanical control. Alternatively, solid state nanopores can be fabricated through a membrane, supporting the ring. Both configuration are discussed in this paper, in term of implementation and sensitivity.

  10. Magnetoresistance peculiarities of bismuth wires in high magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Condrea, E., E-mail: condrea@nano.asm.md [Institute of Electronic Engineering and Nanotechnologies, Academy of Science of Moldova, 2028 Chisinau, Republic of Moldova (Moldova, Republic of); International Laboratory of High Magnetic Fields and Low Temperatures, Gajowicka 95, 51-421 Wroclaw (Poland); Gilewski, A. [International Laboratory of High Magnetic Fields and Low Temperatures, Gajowicka 95, 51-421 Wroclaw (Poland); MagNet, 50-421 Wroclaw (Poland); Nicorici, A. [Institute of Electronic Engineering and Nanotechnologies, Academy of Science of Moldova, 2028 Chisinau, Republic of Moldova (Moldova, Republic of)

    2016-03-11

    Magnetoresistance measurements of Bi wires performed in the magnetic field oriented along the bisector axis revealed unexpected anomalous peaks in a high magnetic field far above the quantum limit of the electrons. By combining a magnetic field and an uniaxial strain, we obtained a modification of the electronic structure; as a result, the quantum limit for light and heavy electrons is changed in a different way. For the case where heavy electrons are in the quantum limit, a correlation between the exit of the lowest Landau level of light electrons and the Lifshitz transition was found. - Highlights: • Glass-coated single-crystalline Bi wires attain high limit of elastic strain of up to 3.0%. • Selective modification of the electronic structure of Bi wires is obtained by combining a high magnetic field and uniaxial strain. • The correlation between the exit of the lowest Landau level of electrons and Lifshitz transition was found.

  11. High resolution remanent magnetization scanner for long cores

    Science.gov (United States)

    Demory, François; Quesnel, Yoann; Uehara, Minoru; Rochette, Pierre; Zylberman, William; Romey, Carole; Pignol, Laure; Andrieu-Ponel, Valérie

    2017-04-01

    Superconducting rock magnetometer reaches saturation when measuring magnetic moments higher than 5 10-5 Am2. Due to the distance of the sensor from the measurement zone, the spatial resolution is low for continuous measurements led on U channel or cores. To solve these problems, we designed a core logger dedicated to the measurement of remanent magnetizations. Based on a fluxgate sensor located very close to the sample, the spatial resolution of the core logger is infra-centimetric. The fluxgate sensor is also able to detect magnetic fields of few nT produced by magnetic moments of the order of few 10-8 Am2. As the equipment does not reach saturation, we measured isothermal remanent magnetization of highly magnetic samples. This magnetization was acquired perpendicularly to the long axis of U-channels from Cassis paleo-lake (Romey et al., 2015) and of cores from Haughton impact structure (Zylberman et al., submitted) using Halbach cylinders (Rochette et al., 2001). To interpret local magnetic fields in terms of magnetic moments, we performed an inter-calibration with the superconducting rock magnetometer and signal inversion. This development led to the filing of a patent (FR.16/53142) and is funded by the ECCOREV project MESENVIMAG. References: Rochette, P., Vadeboin, F., Clochard, L., 2001. Rock magnetic applications of Halbach cylinders. Physics of the Earth and Planetary Interiors 126, 109-117. Romey, C., Vella, C., Rochette, P., Andrieu-Ponel, V., Magnin, F., Veron, A., Talon, B., Landure, C., D'Ovidio, A.M., Delanghe, D., Ghilardi, M., Angeletti, B., 2015. Environmental imprints of landscape evolution and human activities during the Holocene in a small catchment of the Calanques Massif (Cassis, southern France). Holocene 25 (9), 1454-1469. Zylberman W., Quesnel Y., Rochette P., Osinski G. R., Marion C., Gattacceca J. (submitted to MAPS) Hydrothermally-enhanced magnetization at the center of the Haughton impact structure? (Nunavut, Canada).

  12. Highly Mass-Sensitive Thin Film Plate Acoustic Resonators (FPAR

    Directory of Open Access Journals (Sweden)

    Ventsislav Yantchev

    2011-07-01

    Full Text Available The mass sensitivity of thin aluminum nitride (AlN film S0 Lamb wave resonators is theoretically and experimentally studied. Theoretical predictions based on modal and finite elements method analysis are experimentally verified. Here, two-port 888 MHz synchronous FPARs are micromachined and subsequently coated with hexamethyl-disiloxane(HMDSO-plasma-polymerized thin films of various thicknesses. Systematic data on frequency shift and insertion loss versus film thickness are presented. FPARs demonstrate high mass-loading sensitivity as well as good tolerance towards the HMDSO viscous losses. Initial measurements in gas phase environment are further presented.

  13. Instruction manual for ORNL tandem high abundance sensitivity mass spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Smith, D.H.; McKown, H.S.; Chrisite, W.H.; Walker, R.L.; Carter, J.A.

    1976-06-01

    This manual describes the physical characteristics of the tandem mass spectrometer built by Oak Ridge National Laboratory for the International Atomic Energy Agency. Specific requirements met include ability to run small samples, high abundance sensitivity, good precision and accuracy, and adequate sample throughput. The instrument is capable of running uranium samples as small as 10/sup -12/ g and has an abundance sensitivity in excess of 10/sup 6/. Precision and accuracy are enhanced by a special sweep control circuit. Sample throughput is 6 to 12 samples per day. Operating instructions are also given.

  14. Electrooptic modulation methods for high sensitivity tunable diode laser spectroscopy

    Science.gov (United States)

    Glenar, David A.; Jennings, Donald E.; Nadler, Shacher

    1990-01-01

    A CdTe phase modulator and low power RF sources have been used with Pb-salt tunable diode lasers operating near 8 microns to generate optical sidebands for high sensitivity absorption spectroscopy. Sweep averaged, first-derivative sample spectra of CH4 were acquired by wideband phase sensitive detection of the electrooptically (EO) generated carrier-sideband beat signal. EO generated beat signals were also used to frequency lock the TDL to spectral lines. This eliminates low frequency diode jitter, and avoids the excess laser linewidth broadening that accompanies TDL current modulation frequency locking methods.

  15. Bringing Earth Magnetism Research into the High School Physics Classroom

    Science.gov (United States)

    Smirnov, A. V.; Bluth, G.; Engel, E.; Kurpier, K.; Foucher, M. S.; Anderson, K. L.

    2015-12-01

    We present our work in progress from an NSF CAREER project that aims to integrate paleomagnetic research and secondary school physics education. The research project is aimed at quantifying the strength and geometry of the Precambrian geomagnetic field. Investigation of the geomagnetic field behavior is crucial for understanding the mechanisms of field generation, and the development of the Earth's atmosphere and biosphere, and can serve as a focus for connecting high-level Earth science research with a standard physics curriculum. High school science teachers have participated in each summer field and research component of the project, gaining field and laboratory research experience, sets of rock and mineral samples, and classroom-tested laboratory magnetism activities for secondary school physics and earth science courses. We report on three field seasons of teacher field experiences and two years of classroom testing of paleomagnetic research materials merged into physics instruction on magnetism. Students were surveyed before and after dedicated instruction for both perceptions and attitude towards earth science in general, then more specifically on earth history and earth magnetism. Students were also surveyed before and after instruction on major earth system and magnetic concepts and processes, particularly as they relate to paleomagnetic research. Most students surveyed had a strongly positive viewpoint towards the study of Earth history and the importance of studying Earth Sciences in general, but were significantly less drawn towards more specific topics such as mineralogy and magnetism. Students demonstrated understanding of Earth model and the basics of magnetism, as well as the general timing of life, atmospheric development, and magnetic field development. However, detailed knowledge such as the magnetic dynamo, how the magnetic field has changed over time, and connections between earth magnetism and the development of an atmosphere remained largely

  16. High Sensitivity Very Low Frequency Receiver for Earthquake Data Acquisition.

    Science.gov (United States)

    Munir, A.; Najmurrokhman, A.

    2017-03-01

    high sensitivity very low frequency (VLF) receiver is developed based on AD744 monolithic operational amplifier (Op-Amp) for earthquake data acquisition. In research related natural phenomena such as atmospheric noise, lightning and earthquake, a VLF receiver particularly with high sensitivity is utterly required due to the low power of VLF wave signals received by the antenna. The developed receiver is intended to have high sensitivity reception for the signals in frequency range of 10-30kHz allocated for earthquake observation. The VLF receiver which is portably designed is also equipped with an output port connectable to the soundcard of personal computer for further data acquisition. After obtaining the optimum design, the hardware realization is implemented on a printed circuit board (PCB) for experimental characterization. It shows that the sensitivity of realized VLF receiver is almost linear in the predefined frequency range for the input signals lower than -12dBm and to be quadratic for the higher level input signals.

  17. A magnetic nanoparticle-based aptasensor for selective and sensitive determination of lysozyme with strongly scattering silver nanoparticles.

    Science.gov (United States)

    Li, Chun Mei; Zhan, Lei; Zheng, Lin Ling; Li, Yuan Fang; Huang, Cheng Zhi

    2016-05-10

    Qualitative and quantitative determination of lysozyme concentrations in urine and serum with high selectivity and sensitivity is important for diagnosing the progression of several diseases. In this report, we devised an improved method for specifically detecting lysozyme by combining magnetic nanoparticles (for separation and enrichment), an aptamer (for selective binding of lysozyme) and strongly scattering silver nanoparticles (AgNPs, for detection by light scattering, but also providing another level of selectivity due to their electrostatic binding with lysozyme). In this system, 0.4-30 nM lysozyme could be simply detected owing to the decreased light scattering of AgNPs in solution after magnetic separation, with a detection limit of 100 pM. In addition, lysozyme was also able to be semi-quantified by using the dark-field light scattering images of AgNPs after enrichment by the MNP-apt-lysozyme complex. Moreover, this design shows great promise for the robust and reliable detection of lysozyme in real samples, with a recovery rate ranging from 98.6% to 101.3% in human serum samples. Therefore, this assay provided robust measurements with good specificity, sensitivity, and tolerance of changes in the sample matrix. We expect that this MNP-based aptasensor may find utility in the accurate diagnosis of lysozyme-related diseases.

  18. Synthesis of pH-sensitive and recyclable magnetic nanoparticles for efficient separation of emulsified oil from aqueous environments

    Science.gov (United States)

    Lü, Ting; Zhang, Shuang; Qi, Dongming; Zhang, Dong; Vance, George F.; Zhao, Hongting

    2017-02-01

    Emulsified oil wastewaters, arisen from oil industry and oil spill accidents, cause severe environmental and ecological problems. In this study, a series of pH-sensitive magnetic nanomaterials (MNPs) were synthesized and characterized for their evaluation in separation of emulsified oil from aqueous environments. A coprecipitation method was used to produce Fe3O4 magnetic nanoparticles that were coated in a 2-step process with first silica to form a surface for anchoring an (3-aminopropyl)triethoxysilane (APTES) molecular layer. Detailed studies were conducted on effects of MNPs dosage, APTES anchoring density (DA) and pH on oil-water separation performance of the synthetic MNPs. Results showed that, under both acidic and neutral conditions, MNPs with high DA exhibited enhanced oil-water separation performance, while under alkaline condition, the oil-water separation process was minimal. Alkaline conditions allowed the MNPs to be recycled up to 9 cycles without showing any significant decrease in oil-water separation efficiency. An examination of the oil-water separation mechanism found that electrostatic interaction and interfacial activity both played important roles in oil-water separation. In conclusion, pH-sensitive MNPs can be easily synthesized and recycled, providing a promising, cost-effective and environmentally-friendly process for the efficient treatment of emulsified oil wastewater.

  19. τ-MnAl with high coercivity and saturation magnetization

    Directory of Open Access Journals (Sweden)

    J. Z. Wei

    2014-12-01

    Full Text Available In this paper, high purity τ-Mn54Al46 and Mn54−xAl46Cxalloys were successfully prepared using conventional arc-melting, melt-spinning, and heat treatment process. The magnetic and the structural properties were examined using x-ray diffraction (XRD, powder neutron diffraction and magnetic measurements. A room temperature saturation magnetization of 650.5 kAm-1, coercivity of 0.5 T, and a maximum energy product of (BHmax = 24.7 kJm-3 were achieved for the pure Mn54Al46 powders without carbon doping. The carbon substituted Mn54−xAl46Cx, however, reveals a lower Curie temperature but similar saturation magnetization as compared to the carbon-free sample. The electronic structure of MnAl shows that the Mn atom possesses a magnetic moment of 2.454 μB which results from strong hybridization between Mn-Al and Mn-Mn. We also investigated the volume and c/a ratio dependence of the magnetic moments of Mn and Al. The results indicate that an increase in the intra-atomic exchange splitting due to the cell volume expansion, leads to a large magnetic moment for the Mn atom. The Mn magnetic moment can reach a value of 2.9 μB at a volume expansion rate of ΔV/V ≈ 20%.

  20. Establishing resolution-improved NMR spectroscopy in high magnetic fields with unknown spatiotemporal variations

    Science.gov (United States)

    Zhang, Zhiyong; Smith, Pieter E. S.; Cai, Shuhui; Zheng, Zhenyao; Lin, Yulan; Chen, Zhong

    2015-12-01

    A half-century quest for higher magnetic fields has been an integral part of the progress undergone in the Nuclear Magnetic Resonance (NMR) study of materials' structure and dynamics. Because 2D NMR relies on systematic changes in coherences' phases as a function of an encoding time varied over a series of independent experiments, it generally cannot be applied in temporally unstable fields. This precludes most NMR methods from being used to characterize samples situated in hybrid or resistive magnets that are capable of achieving extremely high magnetic field strength. Recently, "ultrafast" NMR has been developed into an effective and widely applicable methodology enabling the acquisition of a multidimensional NMR spectrum in a single scan; it can therefore be used to partially mitigate the effects of temporally varying magnetic fields. Nevertheless, the strong interference of fluctuating fields with the spatial encoding of ultrafast NMR still severely restricts measurement sensitivity and resolution. Here, we introduce a strategy for obtaining high resolution NMR spectra that exploits the immunity of intermolecular zero-quantum coherences (iZQCs) to field instabilities and inhomogeneities. The spatial encoding of iZQCs is combined with a J-modulated detection scheme that removes the influence of arbitrary field inhomogeneities during acquisition. This new method can acquire high-resolution one-dimensional NMR spectra in large inhomogeneous and fluctuating fields, and it is tested with fields experimentally modeled to mimic those of resistive and resistive-superconducting hybrid magnets.

  1. High Sensitivity Polymer Optical Fiber-Bragg-Grating-Based Accelerometer

    DEFF Research Database (Denmark)

    Stefani, Alessio; Andresen, Søren; Yuan, Wu

    2012-01-01

    We report on the fabrication and characterization of the first accelerometer based on a polymer optical fiber Bragg grating (FBG) for operation at both 850 and 1550 nm. The devices have a flat frequency response over a 1-kHz bandwidth and a resonance frequency of about 3 kHz. The response is linear...... up to at least 15 g and sensitivities as high as 19 pm/g (shift in resonance wavelength per unit acceleration) have been demonstrated. Given that 15 g corresponds to a strain of less than 0.02% and that polymer fibers have an elastic limit of more than 1%, the polymer FBG accelerometer can measure...... very strong accelerations. We compare with corresponding silica FBG accelerometers and demonstrate that using polymer FBGs improves the sensitivity by more than a factor of four and increases the figure of merit, defined as the sensitivity times the resonance frequency squared....

  2. Investigating the Effect of Line Dipole Magnetic Field on Hydrothermal Characteristics of a Temperature-Sensitive Magnetic Nanofluid Using Two-Phase Simulation.

    Science.gov (United States)

    Bahiraei, Mehdi; Hangi, Morteza

    2016-12-01

    Hydrothermal characteristics of a temperature-sensitive magnetic nanofluid between two parallel plates are investigated in the presence of magnetic field produced by one or multiple line dipole(s) using the two-phase mixture model. As the nanofluid reaches the region where the magnetic field is applied, a rotation is developed due to the dependency of magnetization on temperature. This can lead to mixing in the flow and more uniform distribution of temperature due to the disturbance caused in the boundary layer, and consequently, enhancement in convective heat transfer. The results indicate that the disturbance in boundary layer adjacent to the lower wall is more significant than the upper wall. By application of the magnetic field, the convective heat transfer increases locally for both walls. Due to the intensified mixing, a sudden pressure drop occurs when the fluid reaches the region where the magnetic field is applied. For greater magnetic field strengths and lower Reynolds numbers, the improvement in convective heat transfer is more significant. For small magnetic field strengths, the effect of applying magnetic field on the upper wall is much smaller than that on the lower wall; however, this effect becomes almost the same for both walls at great magnetic field strengths.

  3. Induction heating of rotating nonmagnetic billet in magnetic field produced by high-parameter permanent magnets

    Directory of Open Access Journals (Sweden)

    Ivo Doležel

    2014-04-01

    Full Text Available An advanced way of induction heating of nonmagnetic billets is discussed and modeled. The billet rotates in a stationary magnetic field produced by unmoving high-parameter permanent magnets fixed on magnetic circuit of an appropriate shape. The mathematical model of the problem consisting of two coupled partial differential equations is solved numerically, in the monolithic formulation. Computations are carried out using our own code Agros2D based on a fully adaptive higher-order finite element method. The most important results are verified experimentally on our own laboratory device.

  4. Magnetic anisotropy and high-field magnetization process of CeCo[sub 5

    Energy Technology Data Exchange (ETDEWEB)

    Bartashevich, M.I. (Tokyo Univ. (Japan). Inst. for Solid State Physics (ISSP)); Goto, T. (Tokyo Univ. (Japan). Inst. for Solid State Physics (ISSP)); Radwanski, R.J. (Centre for Solid State Physics, Krakow (Poland)); Korolyov, A.V. (Inst. of Metal Physics, Ekaterinburg (Russian Federation))

    1994-03-01

    The magnetization process of single-crystalline CeCo[sub 5] has been measured at various temperatures from 4.2 to 300 K in high magnetic fields up to 40 T. The uniaxial magnetocrystalline anisotropy constant K[sub 1] is found to be about 35% higher than that of YCo[sub 5]. The magnetization anisotropy reaches p = 0.12 at 4.2 K, which is also higher than that of YCo[sub 5]. Both the anisotropies decrease with increasing temperature. These experimental results indicate that Ce in CeCo[sub 5] is in a mixed-valence state. (orig.)

  5. Mitigation of extremely low frequency magnetic fields from electrical installations in high-rise buildings

    Energy Technology Data Exchange (ETDEWEB)

    Burnett, John; Duyaping, Patrick [Hong Kong Polytechnic Univ., Dept. of Building Services Engineering, Kowloon, Hong Kong (China)

    2002-09-01

    The health impacts on people exposed to power line generated magnetic fields remains somewhat controversial. Under certain circumstances, such extremely low frequency (ELF) magnetic fields also arise in high-rise buildings in Hong Kong, causing interference with sensitive equipment, and with it concerns about the potential health impacts on affected persons. Due to a general lack of awareness electrical design and installation engineers rarely consider the issue. This paper discusses the problem of ELF fields generated by a building's electrical distribution system, and provides simplified analytical techniques that lead to practical solutions for eliminating interference problems as well as reducing concerns about health impacts. (Author)

  6. Facility Measures Magnetic Fields

    Science.gov (United States)

    Honess, Shawn B.; Narvaez, Pablo; Mcauley, James M.

    1991-01-01

    Partly automated facility measures and computes steady near magnetic field produced by object. Designed to determine magnetic fields of equipment to be installed on spacecraft including sensitive magnetometers, with view toward application of compensating fields to reduce interfernece with spacecraft-magnetometer readings. Because of its convenient operating features and sensitivity of its measurements, facility serves as prototype for similar facilities devoted to magnetic characterization of medical equipment, magnets for high-energy particle accelerators, and magnetic materials.

  7. Highly Efficient Domain Walls Injection in Perpendicular Magnetic Anisotropy Nanowire.

    Science.gov (United States)

    Zhang, S F; Gan, W L; Kwon, J; Luo, F L; Lim, G J; Wang, J B; Lew, W S

    2016-04-21

    Electrical injection of magnetic domain walls in perpendicular magnetic anisotropy nanowire is crucial for data bit writing in domain wall-based magnetic memory and logic devices. Conventionally, the current pulse required to nucleate a domain wall is approximately ~10(12) A/m(2). Here, we demonstrate an energy efficient structure to inject domain walls. Under an applied electric potential, our proposed Π-shaped stripline generates a highly concentrated current distribution. This creates a highly localized magnetic field that quickly initiates the nucleation of a magnetic domain. The formation and motion of the resulting domain walls can then be electrically detected by means of Ta Hall bars across the nanowire. Our measurements show that the Π-shaped stripline can deterministically write a magnetic data bit in 15 ns even with a relatively low current density of 5.34 × 10(11) A/m(2). Micromagnetic simulations reveal the evolution of the domain nucleation - first, by the formation of a pair of magnetic bubbles, then followed by their rapid expansion into a single domain. Finally, we also demonstrate experimentally that our injection geometry can perform bit writing using only about 30% of the electrical energy as compared to a conventional injection line.

  8. High gradient magnetic separation applied to environmental remediation

    Energy Technology Data Exchange (ETDEWEB)

    Prenger, F.C.; Stewart, W.F.; Hill, D.D.; Avens, L.R.; Worl, L.A.; Schake, A.; Aguero, K.J. de; Padilla, D.D. [Los Alamos National Lab., NM (United States); Tolt, T.L. [Lockheed Environmental Systems and Technology Co., Las Vegas, NV (United States)

    1994-12-31

    High gradient magnetic separation (HGMS) is an application of superconducting magnet technology to the separation of magnetic solids from other solids, liquids, or gases. The production of both high magnetic fields (>4 T) and large field gradients using superconducting magnet technology has made it possible to separate a previously unreachable but large family of paramagnetic materials. This powerful technique can be used to separate widely dispersed contaminants from a host material, and it may be the only technique available for separating material in the colloidal state. Because it is a physical separation process, no additional waste is generated. The authors are applying this technology to the treatment of radioactive wastes for environmental remediation. They have conducted tests examining slurries containing nonradioactive, magnetic surrogates. Results from these studies were used to verify their analytical model of the separation process. The model describes the rate process for magnetic separation and is based on a force balance on the paramagnetic species. This model was used to support bench scale experiments and prototype separator designs.

  9. Magnetic field management of substations in high rise buildings

    Energy Technology Data Exchange (ETDEWEB)

    Farag, A.S.; Al-Shehri, A.M. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia); Cheng, T.C.; Du, Y.; Hu, L.; Penn, D. [Univ. of Southern California, LADWP, Los Angeles, CA (United States)

    1995-12-01

    The electric and magnetic field issue has become an area of increasing public concern. Utilities have been carrying out extensive projects to characterize and manage the magnetic fields around their substations in an effort to answer public concerns over the possible health hazard caused by these fields. This paper describes various techniques available for managing magnetic field strength levels in substations. The design guideline aids in the planning, design, construction of substation facilities. Low-frequency magnetic field is directly associated with current-carrying sources and its magnitude is proportional to the distance from the sources. Distribution substations in high-rise buildings are very close to public areas and the magnetic fields imposed by these substations might be relatively higher than that imposed by outdoor substations. Options to manage these substations fields are considered in this paper. Techniques to manage magnetic fields in substations such as: source relocation, compaction, rephasing, return-current control, passive and active shielding are discussed. Several techniques were applied to reduce the magnetic fields in the conference room located in the main floor above a substation located in the basement of the main office high-rise building of LADWP. 10 refs, 14 figs, 3 tabs

  10. Low-field MRI can be more sensitive than high-field MRI

    Science.gov (United States)

    Coffey, Aaron M.; Truong, Milton L.; Chekmenev, Eduard Y.

    2013-12-01

    MRI signal-to-noise ratio (SNR) is the key factor for image quality. Conventionally, SNR is proportional to nuclear spin polarization, which scales linearly with magnetic field strength. Yet ever-stronger magnets present numerous technical and financial limitations. Low-field MRI can mitigate these constraints with equivalent SNR from non-equilibrium ‘hyperpolarization' schemes, which increase polarization by orders of magnitude independently of the magnetic field. Here, theory and experimental validation demonstrate that combination of field independent polarization (e.g. hyperpolarization) with frequency optimized MRI detection coils (i.e. multi-turn coils using the maximum allowed conductor length) results in low-field MRI sensitivity approaching and even rivaling that of high-field MRI. Four read-out frequencies were tested using samples with identical numbers of 1H and 13C spins. Experimental SNRs at 0.0475 T were ∼40% of those obtained at 4.7 T. Conservatively, theoretical SNRs at 0.0475 T 1.13-fold higher than those at 4.7 T were possible despite an ∼100-fold lower detection frequency, indicating feasibility of high-sensitivity MRI without technically challenging, expensive high-field magnets. The data at 4.7 T and 0.0475 T was obtained from different spectrometers with different RF probes. The SNR comparison between the two field strengths accounted for many differences in parameters such as system noise figures and variations in the probe detection coils including Q factors and coil diameters.

  11. Magnetoresistance peculiarities of bismuth wires in high magnetic field

    Science.gov (United States)

    Condrea, E.; Gilewski, A.; Nicorici, A.

    2016-03-01

    Magnetoresistance measurements of Bi wires performed in the magnetic field oriented along the bisector axis revealed unexpected anomalous peaks in a high magnetic field far above the quantum limit of the electrons. By combining a magnetic field and an uniaxial strain, we obtained a modification of the electronic structure; as a result, the quantum limit for light and heavy electrons is changed in a different way. For the case where heavy electrons are in the quantum limit, a correlation between the exit of the lowest Landau level of light electrons and the Lifshitz transition was found.

  12. Endogenous magnetic reconnection and associated high energy plasma processes

    Science.gov (United States)

    Coppi, B.; Basu, B.

    2018-02-01

    An endogenous reconnection process involves a driving factor that lays inside the layer where a drastic change of magnetic field topology occurs. A process of this kind is shown to take place when an electron temperature gradient is present in a magnetically confined plasma and the evolving electron temperature fluctuations are anisotropic. The width of the reconnecting layer remains significant even when large macroscopic distances are considered. In view of the fact that there are plasmas in the Universe with considerable electron thermal energy contents this feature can be relied upon in order to produce generation or conversion of magnetic energy, high energy particle populations and momentum and angular momentum transport.

  13. Novel magnetic and fluorescent nanocomposite as a sensitive probe for the determination of proteins

    Science.gov (United States)

    Wang, Lun; Hong, Shi; Wang, Leyu; Dong, Li; Bian, Guirong; Xia, Tingting; Chen, Hongqi

    2006-10-01

    The Fe 3O 4/(sodium oleic acid/ethyltrimethyl ammonium bromide) n/4-aminobenzoic acid (Fe 3O 4/(NaOL/CTAB) n/PABA) nanocomposites have been prepared by a layer-by-layer self-assembly approach. This kind of nanocomposites have fluorescent, magnetic and water-soluble properties. Taking advantage of the magnetic property of nanocomposites, we can separated them from solution easily by using a permanent magnet. By using their strong fluorescence, we can detect proteins. At pH 6.98, the fluorescence of Fe 3O 4/(NaOL/CTAB) n/PABA nanocomposites can be enhanced by the proteins. Under optimal conditions, the linear ranges of calibration curves were 0.2-20, 0.2-13, 0.2-10 μg mL -1 for γ-globulin (γ-IgG), human serum albumin (HSA), and bovine serum albumin (BSA), respectively. The detection limits were 0.02, 0.01, 0.02 for γ-IgG, HSA and BSA, respectively. The method has been applied to analyze the total proteins in human samples and the results were in good agreement with those reported by the hospital. This method is sensitive, simple and potential in many areas.

  14. Prototype of haptic device for sole of foot using magnetic field sensitive elastomer

    Science.gov (United States)

    Kikuchi, T.; Masuda, Y.; Sugiyama, M.; Mitsumata, T.; Ohori, S.

    2013-02-01

    Walking is one of the most popular activities and a healthy aerobic exercise for the elderly. However, if they have physical and / or cognitive disabilities, sometimes it is challenging to go somewhere they don't know well. The final goal of this study is to develop a virtual reality walking system that allows users to walk in virtual worlds fabricated with computer graphics. We focus on a haptic device that can perform various plantar pressures on users' soles of feet as an additional sense in the virtual reality walking. In this study, we discuss a use of a magnetic field sensitive elastomer (MSE) as a working material for the haptic interface on the sole. The first prototype with MSE was developed and evaluated in this work. According to the measurement of planter pressures, it was found that this device can perform different pressures on the sole of a light-weight user by applying magnetic field on the MSE. The result also implied necessities of the improvement of the magnetic circuit and the basic structure of the mechanism of the device.

  15. The Behavior Of Asymmetric Frontal Couplings With Permanent Magnets In Magnetic Powder And High Temperature Environments

    Directory of Open Access Journals (Sweden)

    Ion DOBROTA

    2002-12-01

    Full Text Available The main purpose of this paper is the comparative analysis of the behavior of frontal couplings with Nd-Fe-B permanent magnets in difficult environments, specific to metallurgy – such as environments with magnetic powders and high temperature – in two constructive variants: symmetric couplings and asymmetric couplings (with divided poles. The results show the superior performance of asymmetric couplings under the given conditions

  16. Superconductor Requirements and Characterization for High Field Accelerator Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Barzi, E.; Zlobin, A. V.

    2015-05-01

    The 2014 Particle Physics Project Prioritization Panel (P5) strategic plan for U.S. High Energy Physics (HEP) endorses a continued world leadership role in superconducting magnet technology for future Energy Frontier Programs. This includes 10 to 15 T Nb3Sn accelerator magnets for LHC upgrades and a future 100 TeV scale pp collider, and as ultimate goal that of developing magnet technologies above 20 T based on both High Temperature Superconductors (HTS) and Low Temperature Superconductors (LTS) for accelerator magnets. To achieve these objectives, a sound conductor development and characterization program is needed and is herein described. This program is intended to be conducted in close collaboration with U.S. and International labs, Universities and Industry.

  17. Development of high magnetic fields for energy research

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, J.D.; Campbell, L.J.; Modler, R.; Movshovich, R. [Los Alamos National Lab., NM (United States); Lawrence, J.M. [Univ. of California, Irvine, CA (United States); Awschalom, D.D. [Univ. of California, Santa Barbara, CA (United States)

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The primary purpose of work has been to develop the scientific basis for DOE support of a program that would build a novel, nondestructive 100-tesla magnet that would be available as a user facility for cutting-edge, energy-related research and technology at very high magnetic fields.

  18. Anticipation of interoceptive threat in highly anxiety sensitive persons.

    Science.gov (United States)

    Melzig, Christiane A; Michalowski, Jaroslaw M; Holtz, Katharina; Hamm, Alfons O

    2008-10-01

    Anticipatory anxiety plays a major role in the etiology of panic disorder. Although anticipatory anxiety elicited by expectation of interoceptive cues is specifically relevant for panic patients, it has rarely been studied. Using a population analogue in high fear of such interoceptive arousal sensations (highly anxiety sensitive persons) we evaluated a new experimental paradigm to assess anticipatory anxiety during anticipation of interoceptive (somatic sensations evoked by hyperventilation) and exteroceptive (electric shock) threat. Symptom reports, autonomic arousal, and defensive response mobilization (startle eyeblink response) were monitored during threat and matched safe conditions in 26 highly anxiety sensitive persons and 22 controls. The anticipation of exteroceptive threat led to a defensive and autonomic mobilization as indexed by a potentiation of the startle response and an increase in skin conductance level in both experimental groups. During interoceptive threat, however, only highly anxiety sensitive persons but not the controls exhibited a startle response potentiation as well as autonomic activation. The anticipation of a hyperventilation procedure thus seems a valid paradigm to investigate anticipatory anxiety elicited by interoceptive cues in the clinical context.

  19. High-Performance Ruthenium Sensitizers Containing Imidazolium Counterions for Efficient Dye Sensitization in Water.

    Science.gov (United States)

    Li, Xiaoyu; Li, Shiqing; Gao, Ge; Wu, Di; Lan, Jingbo; Wang, Ruilin; You, Jingsong

    2017-07-21

    A new type of water-soluble ruthenium sensitizers incorporating imidazolium counterions, denoted [DMPI]2 -Ru and [DMHI]2 -Ru, has been developed, which can be efficiently adsorbed onto TiO2 photoanodes in aqueous solution. Owing to the good thermal stability of imidazolium, [DMPI]2 -Ru adsorbed on TiO2 has a higher decomposition temperature than N719 dye [di(tetrabutylammonium) cis-di(thiocyanato)bis(2,2'-bipyridine-4,4'-dicarboxylato)ruthenium(II)]. When using organic solvent-based I- /I3- electrolytes, solars cell based on [DMPI]2 -Ru-sensitized TiO2 in water show high power conversion efficiencies (PCE) of up to 10.2 %, which is higher than that of N719 (9.9 %) under the common conditions for dye sensitization in organic solvent. [DMHI]2 -Ru, with poorer water solubility than [DMPI]2 -Ru, gives a smaller dye-adsorption amount on TiO2 and thus a lower PCE of 9.4 %. From the viewpoint of safety and environmental impact, the fabrication of dye-sensitized solar cells (DSSCs) by using water as solvent is undoubtedly a preferable strategy. Although the [DMPI]2 -Ru-based device fabricated by using water as the solvent for both the dye-sensitization process and the electrolyte gives a relatively low efficiency, it provides a promising approach for the practical application of DSSCs. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. FeSiBP bulk metallic glasses with high magnetization and excellent magnetic softness

    Science.gov (United States)

    Makino, Akihiro; Kubota, Takeshi; Chang, Chuntao; Makabe, Masahiro; Inoue, Akihisa

    Fe-based amorphous alloy ribbons are one of the major soft magnetic materials, because of their superior magnetic properties such as the relatively high saturation magnetization ( Js) of 1.5-1.6 T and good magnetic softness. However, the preparation of the ordinary amorphous magnetic alloys requires cooling rates higher than 10 4 K/s due to the low glass-forming ability (GFA) and thus restricts the material outer shape. Recently, Fe-metalloid-based bulk metallic glasses (BMGs) containing glass-forming elements such as Al, Ga, Nb, Mo, Y and so forth have been developed. These alloys have high GFA, leading to the formation of BMG rod with diameters of mm-order. However, the glass-forming metal elements in BMGs result in a remarkable decrease in magnetization. Basically, Js depends on Fe content; hence, high Js requires high Fe content in the Fe-based amorphous alloys or BMGs. On the other hand, high GFA requires a large amount of glass-forming elements in the alloys, which results in lower Fe content. Therefore, in substances, the coexistence of high Js and high GFA is difficult. Since this matter should be immensely important from academia to industry in the material field, a great deal of effort has been devoted; however, it has remained unsolved for many years. In this paper, we present a novel Fe-rich FeSiBP BMG with high Js of 1.51 T comparable to the ordinary Fe-Si-B amorphous alloy now in practical use as well as with high GFA leading to a rod-shaped specimen of 2.5 mm in diameter, obtained by Cu-mold casting in air.

  1. Highly sensitive troponin T in patients with acute ischemic stroke

    DEFF Research Database (Denmark)

    Jensen, J K; Ueland, T; Aukrust, P

    2012-01-01

    in decedents than in survivors. After adjustment for stroke severity, C-reactive protein, age, NT-proBNP and prior heart and/or renal failure, hsTnT levels were not a significant predictor of long-term all-cause or cardiovascular mortality. Conclusion: Elevated levels of hsTnT are frequently present......Background: Newly developed troponin assays have superior diagnostic and prognostic performance in acute coronary syndrome (ACS), when compared to conventional troponin assays; however, highly sensitive troponin has not been evaluated in patients with acute ischemic stroke. Methods: Highly...... sensitive troponin T (hsTnT) was measured daily during the first 4 days in 193 consecutive patients with acute ischemic stroke without overt ACS or atrial fibrillation. The patients were previously tested normal with a fourth-generation TnT assay. The patients were followed for 47 months, with all...

  2. Pushing the sensitivity envelope of lanthanide-based magnetic resonance imaging (MRI) contrast agents for molecular imaging applications.

    Science.gov (United States)

    Aime, Silvio; Castelli, Daniela Delli; Crich, Simonetta Geninatti; Gianolio, Eliana; Terreno, Enzo

    2009-07-21

    Contrast in magnetic resonance imaging (MRI) arises from changes in the intensity of the proton signal of water between voxels (essentially, the 3D counterpart of pixels). Differences in intervoxel intensity can be significantly enhanced with chemicals that alter the nuclear magnetic resonance (NMR) intensity of the imaged spins; this alteration can occur by various mechanisms. Paramagnetic lanthanide(III) complexes are used in two major classes of MRI contrast agent: the well-established class of Gd-based agents and the emerging class of chemical exchange saturation transfer (CEST) agents. A Gd-based complex increases water signal by enhancing the longitudinal relaxation rate of water protons, whereas CEST agents decrease water signal as a consequence of the transfer of saturated magnetization from the exchangeable protons of the agent. In this Account, we survey recent progress in both areas, focusing on how MRI is becoming a more competitive choice among the various molecular imaging methods. Compared with other imaging modalities, MRI is set apart by its superb anatomical resolution; however, its success in molecular imaging suffers because of its intrinsic insensitivity. A relatively high concentration of molecular agents (0.01-0.1 mM) is necessary to produce a local alteration in the water signal intensity. Unfortunately, the most desirable molecules for visualization in molecular imaging are present at much lower concentrations, in the nano- or picomolar range. Therefore, augmenting the sensitivity of MRI agents is key to the development of MR-based molecular imaging applications. In principle, this task can be tackled either by increasing the sensitivity of the reporting units, through the optimization of their structural and dynamic properties, or by setting up proper amplification strategies that allow the accumulation of a huge number of imaging reporters at the site of interest. For Gd-based agents, high sensitivities can be attained by exploiting a

  3. Homogenous BSCCO-2212 Round Wires for Very High Field Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Scott Campbell

    2012-06-30

    The performance demands on modern particle accelerators generate a relentless push towards higher field magnets. In turn, advanced high field magnet development places increased demands on superconducting materials. Nb3Sn conductors have been used to achieve 16 T in a prototype dipole magnet and are thought to have the capability for {approx}18 T for accelerator magnets (primarily dipoles but also higher order multipole magnets). However there have been suggestions and proposals for such magnets higher than 20 T. The High Energy Physics Community (HEP) has identified important new physics opportunities that are enabled by extremely high field magnets: 20 to 50 T solenoids for muon cooling in a muon collider (impact: understanding of neutrinos and dark matter); and 20+ T dipoles and quadrupoles for high energy hadron colliders (impact: discovery reach far beyond present). This proposal addresses the latest SBIR solicitation that calls for grant applications that seek to develop new or improved superconducting wire technologies for magnets that operate at a minimum of 12 Tesla (T) field, with increases up to 15 to 20 T sought in the near future (three to five years). The long-term development of accelerator magnets with fields greater than 20 T will require superconducting wires having significantly better high-field properties than those possessed by current Nb{sub 3}Sn or other A15 based wires. Given the existing materials science base for Bi-2212 wire processing, we believe that Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} (Bi-2212) round wires can be produced in km-long piece lengths with properties suitable to meet both the near term and long term needs of the HEP community. The key advance will be the translation of this materials science base into a robust, high-yield wire technology. While the processing and application of A15 materials have advanced to a much higher level than those of the copper oxide-based, high T{sub c} (HTS) counterparts, the HTS materials have

  4. Structural Glycomic Analyses at High Sensitivity: A Decade of Progress

    Science.gov (United States)

    Alley, William R.; Novotny, Milos V.

    2014-01-01

    The field of glycomics has recently advanced in response to the urgent need for structural characterization and quantification of complex carbohydrates in biologically and medically important applications. The recent success of analytical glycobiology at high sensitivity reflects numerous advances in biomolecular mass spectrometry and its instrumentation, capillary and microchip separation techniques, and microchemical manipulations of carbohydrate reactivity. The multimethodological approach appears to be necessary to gain an in-depth understanding of very complex glycomes in different biological systems. PMID:23560930

  5. Sensitivity to Envelope Interaural Time Differences at High Modulation Rates

    Science.gov (United States)

    Bleeck, Stefan; McAlpine, David

    2015-01-01

    Sensitivity to interaural time differences (ITDs) conveyed in the temporal fine structure of low-frequency tones and the modulated envelopes of high-frequency sounds are considered comparable, particularly for envelopes shaped to transmit similar fidelity of temporal information normally present for low-frequency sounds. Nevertheless, discrimination performance for envelope modulation rates above a few hundred Hertz is reported to be poor—to the point of discrimination thresholds being unattainable—compared with the much higher (>1,000 Hz) limit for low-frequency ITD sensitivity, suggesting the presence of a low-pass filter in the envelope domain. Further, performance for identical modulation rates appears to decline with increasing carrier frequency, supporting the view that the low-pass characteristics observed for envelope ITD processing is carrier-frequency dependent. Here, we assessed listeners’ sensitivity to ITDs conveyed in pure tones and in the modulated envelopes of high-frequency tones. ITD discrimination for the modulated high-frequency tones was measured as a function of both modulation rate and carrier frequency. Some well-trained listeners appear able to discriminate ITDs extremely well, even at modulation rates well beyond 500 Hz, for 4-kHz carriers. For one listener, thresholds were even obtained for a modulation rate of 800 Hz. The highest modulation rate for which thresholds could be obtained declined with increasing carrier frequency for all listeners. At 10 kHz, the highest modulation rate at which thresholds could be obtained was 600 Hz. The upper limit of sensitivity to ITDs conveyed in the envelope of high-frequency modulated sounds appears to be higher than previously considered. PMID:26721926

  6. Freely suspended nanocomposite membranes as highly sensitive sensors.

    Science.gov (United States)

    Jiang, Chaoyang; Markutsya, Sergiy; Pikus, Yuri; Tsukruk, Vladimir V

    2004-10-01

    Highly sensitive sensor arrays are in high demand for prospective applications in remote sensing and imaging. Measuring microscopic deflections of compliant micromembranes and cantilevers is developing into one of the most versatile approaches for thermal, acoustic and chemical sensing. Here, we report on an innovative fabrication of compliant nanocomposite membranes with nanoscale thickness showing extraordinary sensitivity and dynamic range, which makes them candidates for a new generation of membrane-based sensor arrays. These nanomembranes with a thickness of 25-70 nm, which can be freely suspended over large (hundred micrometres) openings are fabricated with molecular precision by time-efficient, spin-assisted layer-by-layer assembly. They are designed as multilayered molecular composites made of a combination of polymeric monolayers and a metal nanoparticle intralayer. We demonstrate that these nanocomposite membranes possess unparalleled sensitivity and a unique autorecovering ability. The membrane nanostructure that is responsible for these outstanding properties combines multilayered polymer/nanoparticle organization, high polymer-chain orientation, and a pre-stretched state.

  7. High-sensitivity active pixel sensor with variable threshold photodetector

    Science.gov (United States)

    Jo, Sung-Hyun; Bae, Myunghan; Choi, Byoung-Soo; Lyu, Hong-Kun; Shin, Jang-Kyoo

    2015-05-01

    A novel high-sensitivity active pixel sensor (APS) with a variable threshold photodetector has been presented and for the first time, a simple SPICE model for the variable threshold photodetector is presented. Its SPICE model is in good agreement with measurements and is more simpler than the conventional model. The proposed APS has a gate/body-tied PMOSFET-type photodetector with an overlapping control gate that makes it possible to control the sensitivity of the proposed APS. It is a hybrid device composed of a metal-oxide-semiconductor field-effect transistor (MOSFET), a lateral bipolar junction transistor (BJT) and a vertical BJT. Using sufficient overlapping control gate bias to operate the MOSFET in inversion mode, the variable threshold photodetector allows for increasing the photocurrent gain by 105 at low light intensities when the control gate bias is -3 V. Thus, the proposed APS with a variable threshold photodetector has better low-light-level sensitivity than the conventional APS operating mode, and it has a variable sensitivity which is determined by the control gate bias. The proposed sensor has been fabricated by using 0.35 μm 2-poly 4-metal standard complementary MOS (CMOS) process and its characteristics have been evaluated.

  8. High-sensitivity bend angle measurements using optical fiber gratings.

    Science.gov (United States)

    Rauf, Abdul; Zhao, Jianlin; Jiang, Biqiang

    2013-07-20

    We present a high-sensitivity and more flexible bend measurement method, which is based on the coupling of core mode to the cladding modes at the bending region in concatenation with optical fiber grating serving as band reflector. The characteristics of a bend sensing arm composed of bending region and optical fiber grating is examined for different configurations including single fiber Bragg grating (FBG), chirped FBG (CFBG), and double FBGs. The bend loss curves for coated, stripped, and etched sections of fiber in the bending region with FBG, CFBG, and double FBG are obtained experimentally. The effect of separation between bending region and optical fiber grating on loss is measured. The loss responses for single FBG and CFBG configurations are compared to discover the effectiveness for practical applications. It is demonstrated that the sensitivity of the double FBG scheme is twice that of the single FBG and CFBG configurations, and hence acts as sensitivity multiplier. The bend loss response for different fiber diameters obtained through etching in 40% hydrofluoric acid, is measured in double FBG scheme that resulted in a significant increase in the sensitivity, and reduction of dead-zone.

  9. Highly Sensitive Detection of Protein Biomarkers with Organic Electrochemical Transistors.

    Science.gov (United States)

    Fu, Ying; Wang, Naixiang; Yang, Anneng; Law, Helen Ka-Wai; Li, Li; Yan, Feng

    2017-11-01

    The analysis of protein biomarkers is of great importance in the diagnosis of diseases. Although many convenient and low-cost electrochemical approaches have been extensively investigated, they are not sensitive enough in the detection of protein biomarkers with low concentrations in physiological environments. Here, this study reports a novel organic-electrochemical-transistor-based biosensor that can successfully detect cancer protein biomarkers with ultrahigh sensitivity. The devices are operated by detecting electrochemical activity on gate electrodes, which is dependent on the concentrations of proteins labeled with catalytic nanoprobes. The protein sensors can specifically detect a cancer biomarker, human epidermal growth factor receptor 2, down to the concentration of 10(-14) g mL(-1) , which is several orders of magnitude lower than the detection limits of previously reported electrochemical approaches. Moreover, the devices can successfully differentiate breast cancer cells from normal cells at various concentrations. The ultrahigh sensitivity of the protein sensors is attributed to the inherent amplification function of the organic electrochemical transistors. This work paves a way for developing highly sensitive and low-cost biosensors for the detection of various protein biomarkers in clinical analysis in the future. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Colorimetry and SERS dual-mode detection of telomerase activity: combining rapid screening with high sensitivity.

    Science.gov (United States)

    Zong, Shenfei; Wang, Zhuyuan; Chen, Hui; Hu, Guohua; Liu, Min; Chen, Peng; Cui, Yiping

    2014-01-01

    As an important biomarker and therapeutic target, telomerase has attracted considerable attention concerning its detection and monitoring. Here, we present a colorimetry and surface enhanced Raman scattering (SERS) dual-mode telomerase activity detection method, which has several distinctive advantages. First, colorimetric functionality allows rapid preliminary discrimination of telomerase activity by the naked eye. Second, the employment of SERS technique results in greatly improved detection sensitivity. Third, the combination of colorimetry and SERS into one detection system can ensure highly efficacious and sensitive screening of numerous samples. Besides, the avoidance of polymerase chain reaction (PCR) procedures further guarantees fine reliability and simplicity. Generally, the presented method is realized by an "elongate and capture" procedure. To be specific, gold nanoparticles modified with Raman molecules and telomeric repeat complementary oligonucleotide are employed as the colorimetric-SERS bifunctional reporting nanotag, while magnetic nanoparticles functionalized with telomerase substrate oligonucleotide are used as the capturing substrate. Telomerase can synthesize and elongate telomeric repeats onto the capturing substrate. The elongated telomeric repeats subsequently facilitate capturing of the reporting nanotag via hybridization between telomeric repeat and its complementary strand. The captured nanotags can cause a significant difference in the color and SERS intensity of the magnetically separated sediments. Thus both the color and SERS can be used as indicators of the telomerase activity. With fast screening ability and outstanding sensitivity, we anticipate that this method would greatly promote practical application of telomerase-based early-stage cancer diagnosis.

  11. Optical fiber distributed sensing for high temperature superconductor magnets

    Science.gov (United States)

    Scurti, Federico; Schwartz, Justin

    2017-04-01

    Over the last two decades, high temperature superconductors (HTS) have achieved performance and technical maturity that make them an enabling technology or an attractive solution for a number of applications like electric motors and generators, particle accelerators and fusion magnets. One of the remaining challenges that hinders a wide use of HTS and needs to be solved is quench detection, since conventional voltage based quench detection puts HTS magnets at risk. In this work we have developed and experimentally investigated the application of Rayleigh-backscattering interrogated optical fibers (RIOF) to the detection of normal zones in superconducting magnets. Different ways to integrate optical fibers into magnets are explored and the earlier detection of RIOF compared to voltage is demonstrated.

  12. DMSP observations of high latitude Poynting flux during magnetic storms

    Science.gov (United States)

    Huang, Cheryl Y.; Huang, Yanshi; Su, Yi-Jiun; Hairston, Marc R.; Sotirelis, Thomas

    2017-11-01

    Previous studies have demonstrated that energy can enter the high-latitude regions of the Ionosphere-Thermosphere (IT) system on open field lines. To assess the extent of high-latitude energy input, we have carried out a study of Poynting flux measured by the Defense Meteorological Satellite Program (DMSP) satellites during magnetic storms. We report sporadic intense Poynting fluxes measured by four DMSP satellites at polar latitudes during two moderate magnetic storms which occurred in August and September 2011. Comparisons with a widely used empirical model for energy input to the IT system show that the model does not adequately capture electromagnetic (EM) energy at very high latitudes during storms. We have extended this study to include more than 30 storm events and find that intense EM energy is frequently detected poleward of 75° magnetic latitude.

  13. Early diagnosis of blast fungus, Magnaporthe oryzae, in rice plant by using an ultra-sensitive electrically magnetic-controllable electrochemical biosensor.

    Science.gov (United States)

    Yang, Weijuan; Zhang, Hongyan; Li, Mengxue; Wang, Zonghua; Zhou, Jie; Wang, Shihua; Lu, Guodong; Fu, FengFu

    2014-11-19

    As one of the most destructive and widespread disease of rice, Magnaporthe oryzae (also called Magnaporthe grisea) has a significant negative impact on rice production. Therefore, it is still in high demand to develop extremely sensitive and accurate methods for the early diagnosis of Magnaporthe oryzae (M. oryzae). In this study, we developed a novel magnetic-controllable electrochemical biosensor for the ultra sensitive and specific detection of M. oryzae in rice plant by using M. oryzae's chitinases (Mgchi) as biochemical marker and a rice (Oryza sativa) cDNA encoding mannose-binding jacalin-related lectin (Osmbl) as recognition probe. The proposed biosensor combined with the merits of chronoamperometry, electrically magnetic-controllable gold electrode and magnetic beads (MBs)-based palladium nano-particles (PdNPs) catalysis amplification, has an ultra-high sensitivity and specificity for the detection of trace M. oryzae in rice plant. It could be used to detect M. oryzae in rice plant in the initial infection stage (before any symptomatic lesions were observed) to help farmers timely manage the disease. In comparison with previous methods, the proposed method has notable advantages such as higher sensitivity, excellent specificity, short analysis time, robust resistibility to complex matrix and low cost etc. The success in this study provides a reliable approach for the early diagnosis and fast screening of M. oryzae in rice plant. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. An integrated low 1/f noise and high-sensitivity CMOS instrumentation amplifier for TMR sensors

    Science.gov (United States)

    Gao, Zhiqiang; Luan, Bo; Zhao, Jincai; Liu, Xiaowei

    2017-03-01

    In this paper, a very low 1/f noise integrated Wheatstone bridge magnetoresistive sensor ASIC based on magnetic tunnel junction (MTJ) technology is presented for high sensitivity measurements. The present CMOS instrumentation amplifier employs the gain-boost folded-cascode structure based on the capacitive-feedback chopper-stabilized technique. By chopping both the input and the output of the amplifier, combined with MTJ magnetoresistive sensitive elements, a noise equivalent magnetoresistance 1 nT/Hz1/2 at 2 Hz, the equivalent input noise spectral density 17 nV/Hz1/2(@2Hz) is achieved. The chip-scale package of the TMR sensor and the instrumentation amplifier is only about 5 mm × 5 mm × 1 mm, while the whole DC current dissipates only 2 mA.

  15. Fast calculation of magnetic field distribution in magnetic gear for high torque application

    DEFF Research Database (Denmark)

    Zhang, Xiaoxu; Liu, Xiao; Song, Zhanfeng

    2016-01-01

    For applications demanding high torque and high reliability transmission, coaxial magnetic gear (CMG) may be a promising substitute of the mechanical gearbox. However, with the increasing of unit capacity, CMG tends to have a big size with large pole number, which would lead to heavy computation...... burden if finite element method (FEM) is employed. Analytical methods are therefore expected. To date, only the exact subdomain model is capable of precisely predicting the magnetic field behaviors in an analytical manner through solving a matrix equation. However, as pole number of the CMG increases...

  16. Methods of high current magnetic field generator for transcranial magnetic stimulation application

    Energy Technology Data Exchange (ETDEWEB)

    Bouda, N. R., E-mail: nybouda@iastate.edu; Pritchard, J.; Weber, R. J.; Mina, M. [Department of Electrical and Computer engineering, Iowa State University, Ames, Iowa 50011 (United States)

    2015-05-07

    This paper describes the design procedures and underlying concepts of a novel High Current Magnetic Field Generator (HCMFG) with adjustable pulse width for transcranial magnetic stimulation applications. This is achieved by utilizing two different switching devices, the MOSFET and insulated gate bipolar transistor (IGBT). Results indicate that currents as high as ±1200 A can be generated with inputs of +/−20 V. Special attention to tradeoffs between field generators utilizing IGBT circuits (HCMFG{sub 1}) and MOSFET circuits (HCMFG{sub 2}) was considered. The theory of operation, design, experimental results, and electronic setup are presented and analyzed.

  17. Retears of postoperative knee meniscus: findings on magnetic resonance imaging (MRI) and magnetic resonance arthrography (MRA) by using low and high field magnets.

    Science.gov (United States)

    Cardello, Paolo; Gigli, Carlo; Ricci, Alessandra; Chiatti, Leonardo; Voglino, Nicola; Pofi, Enrico

    2009-02-01

    The purpose of this study was to determine the diagnostic performance of magnetic resonance (MR) obtained with intra-articular contrast medium in the evaluation of recurrent meniscal tears using low-field extremity-only and high-field whole-body magnets. Postoperative standard MR examinations and MR arthrographies of 95 knees were reviewed. Patients experiencing pain and disability after meniscal repair underwent standard MR and MR arthrography (Gadoterate meglumine 0.0025 mmol/ml) on both a 0.2-T and 1.5-T magnet. In 52 of 95 patients, second-look arthroscopy was performed; in the remaining 43 of 95 patients, clinical follow-up was used as the standard of reference. Sensitivity, specificity, positive and negative predictive values as well as accuracy of MRI/MR arthrographic signs as meniscal morphologic changes and the presence of contrast medium tracking into the tear at T1- and T2-weighted sequences in the detection of recurrent meniscal tears were determined. All MR and MR arthrograpic signs were sensitive in the detection of recurrent tears (range 80-91%). Abnormal meniscal morphology had low specificity [26% (13/50)] for both the 0.2-T and 1.5-T scanner, whereas accuracy was 55% (52/95) and 57% (54/95), respectively. The presence of contrast medium within the meniscus substance on T2-weighted images had higher value of specificity [84% (42/50)] and accuracy [84% (80/95)] by using low field strength magnet than by using high field strength magnet [74% (37/50) and 81% (77/95), respectively]. Whereas, the increased intrameniscal signal intensity extending to the meniscal surface at T1-weighted sequences after intra-articular contrast medium administration had lower specificity and accuracy on 0.2-T images [84% (42/50) and 82% (78/95), respectively] than on 1.5-T images [90% (45/50) and 88% (84/95), respectively]. A diagnosis of recurrent meniscal tear in a previously arthroscopically repaired meniscus can be made both on 0.2-T and 1.5-T magnets on the basis of

  18. ERO modeling and sensitivity analysis of locally enhanced beryllium erosion by magnetically connected antennas

    Science.gov (United States)

    Lasa, A.; Borodin, D.; Canik, J. M.; Klepper, C. C.; Groth, M.; Kirschner, A.; Airila, M. I.; Borodkina, I.; Ding, R.; Contributors, JET

    2018-01-01

    Experiments at JET showed locally enhanced, asymmetric beryllium (Be) erosion at outer wall limiters when magnetically connected ICRH antennas were in operation. A first modeling effort using the 3D erosion and scrape-off layer impurity transport modeling code ERO reproduced qualitatively the experimental outcome. However, local plasma parameters—in particular when 3D distributions are of interest—can be difficult to determine from available diagnostics and so erosion / impurity transport modeling input relies on output from other codes and simplified models, increasing uncertainties in the outcome. In the present contribution, we introduce and evaluate the impact of improved models and parameters with largest uncertainties of processes that impact impurity production and transport across the scrape-off layer, when simulated in ERO: (i) the magnetic geometry has been revised, for affecting the separatrix position (located 50–60 mm away from limiter surface) and thus the background plasma profiles; (ii) connection lengths between components, which lead to shadowing of ion fluxes, are also affected by the magnetic configuration; (iii) anomalous transport of ionized impurities, defined by the perpendicular diffusion coefficient, has been revisited; (iv) erosion yields that account for energy and angular distributions of background plasma ions under the present enhanced sheath potential and oblique magnetic field, have been introduced; (v) the effect of additional erosion sources, such as charge-exchange neutral fluxes, which are dominant in recessed areas like antennas, has been evaluated; (vi) chemically assisted release of Be in molecular form has been included. Sensitivity analysis highlights a qualitative effect (i.e. change in emission patterns) of magnetic shadowing, anomalous diffusion, and inclusion of neutral fluxes and molecular release of Be. The separatrix location, and energy and angular distribution of background plasma fluxes impact erosion

  19. Polymer-Particle Pressure-Sensitive Paint with High Photostability

    Directory of Open Access Journals (Sweden)

    Yu Matsuda

    2016-04-01

    Full Text Available We propose a novel fast-responding and paintable pressure-sensitive paint (PSP based on polymer particles, i.e. polymer-particle (pp-PSP. As a fast-responding PSP, polymer-ceramic (PC-PSP is widely studied. Since PC-PSP generally consists of titanium (IV oxide (TiO2 particles, a large reduction in the luminescent intensity will occur due to the photocatalytic action of TiO2. We propose the usage of polymer particles instead of TiO2 particles to prevent the reduction in the luminescent intensity. Here, we fabricate pp-PSP based on the polystyrene particle with a diameter of 1 μm, and investigate the pressure- and temperature-sensitives, the response time, and the photostability. The performances of pp-PSP are compared with those of PC-PSP, indicating the high photostability with the other characteristics comparable to PC-PSP.

  20. High derivatives for fast sensitivity analysis in linear magnetodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Petin, P. [ENSIEG, Saint Martin d`Heres (France). Lab. d`Electrotechnique de Grenoble]|[FRMASOFT+CSI, Lyon (France); Coulomb, J.L. [ENSIEG, Saint Martin d`Heres (France). Lab. d`Electrotechnique de Grenoble; Conraux, P. [FRAMASOFT+CSI, Lyon (France)

    1997-03-01

    In this article, the authors present a method of sensitivity analysis using high derivatives and Taylor development. The principle is to find a polynomial approximation of the finite elements solution towards the sensitivity parameters. While presenting the method, they explain why this method is applicable with special parameters only. They applied it on a magnetodynamic problem, simple enough to be able to find the analytical solution with a formal calculus tool. They then present the implementation and the good results obtained with the polynomial, first by comparing the derivatives themselves, then by comparing the approximate solution with the theoretical one. After this validation, the authors present results on a real 2D application and they underline the possibilities of reuse in other fields of physics.

  1. Miniature high speed compressor having embedded permanent magnet motor

    Science.gov (United States)

    Zhou, Lei (Inventor); Zheng, Liping (Inventor); Chow, Louis (Inventor); Kapat, Jayanta S. (Inventor); Wu, Thomas X. (Inventor); Kota, Krishna M. (Inventor); Li, Xiaoyi (Inventor); Acharya, Dipjyoti (Inventor)

    2011-01-01

    A high speed centrifugal compressor for compressing fluids includes a permanent magnet synchronous motor (PMSM) having a hollow shaft, the being supported on its ends by ball bearing supports. A permanent magnet core is embedded inside the shaft. A stator with a winding is located radially outward of the shaft. The PMSM includes a rotor including at least one impeller secured to the shaft or integrated with the shaft as a single piece. The rotor is a high rigidity rotor providing a bending mode speed of at least 100,000 RPM which advantageously permits implementation of relatively low-cost ball bearing supports.

  2. Differentiation of early-stage parkinsonisms using neuromelanin-sensitive magnetic resonance imaging.

    Science.gov (United States)

    Ohtsuka, Chigumi; Sasaki, Makoto; Konno, Kanako; Kato, Kanako; Takahashi, Junko; Yamashita, Fumio; Terayama, Yasuo

    2014-07-01

    The purpose of this study was to investigate whether the signal intensity of the substantia nigra pars compacta (SNc) and locus coeruleus (LC) on neuromelanin-sensitive magnetic resonance imaging (MRI) can discriminate early-stage parkinsonism disorders, for which differential diagnosis is generally difficult. Neuromelanin-sensitive MRI at 3 T was performed in 53 patients with early parkinsonism and 22 healthy controls. After an observation period of >1.5 year, the patients were clinically diagnosed with Parkinson's disease (PD; n = 30), multiple system atrophy with predominant parkinsonism (MSA-P; n = 10), or progressive supranuclear palsy syndrome (PSPS; n = 13). The signal intensity of the lateral, central, and medial parts of the SNc and the LC were measured and the contrast ratios (CR) against adjacent white-matter structures was calculated. The CR of the lateral SNc was lower in the PD and MSA-P groups than in the PSPS and control groups (p = 0.0001-0.05). The CR of the LC was lower in the PD group than in the other groups (p = 0.0001-0.05). Sensitivity and specificity of the CRs for discriminating PD from MSA-P was 60% and 90%, respectively, those for PD/PSPS were 63-88% and 77-92%, respectively, and those for MSA-P/PSPS were 80% and 85%, respectively. These properties were comparable or better to MIBG scintigraphy. Neuromelanin-sensitive MRI can depict differences in signal intensity of the lateral SNc and the LC among the parkinsonism disorders at their early stages. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Highly Charged Ions in Rare Earth Permanent Magnet Penning Traps

    CERN Document Server

    Guise, Nicholas D; Tan, Joseph N

    2013-01-01

    A newly constructed apparatus at the National Institute of Standards and Technology (NIST) is designed for the isolation, manipulation, and study of highly charged ions. Highly charged ions are produced in the NIST electron-beam ion trap (EBIT), extracted through a beamline that selects a single mass/charge species, then captured in a compact Penning trap. The magnetic field of the trap is generated by cylindrical NdFeB permanent magnets integrated into its electrodes. In a room-temperature prototype trap with a single NdFeB magnet, species including Ne10+ and N7+ were confined with storage times of order 1 second, showing the potential of this setup for manipulation and spectroscopy of highly charged ions in a controlled environment. Ion capture has since been demonstrated with similar storage times in a more-elaborate Penning trap that integrates two coaxial NdFeB magnets for improved B-field homogeneity. Ongoing experiments utilize a second-generation apparatus that incorporates this two-magnet Penning tra...

  4. Magnetic forces in high-Tc superconducting bearings

    Science.gov (United States)

    Moon, F. C.

    1991-01-01

    In September 1987, researchers at Cornell levitated a small rotor on superconducting bearings at 10,000 rpm. In April 1989, a speed of 120,000 rpm was achieved in a passive bearing with no active control. The bearing material used was YBa2Cu307. There is no evidence that the rotation speed has any significant effect on the lift force. Magnetic force measurements between a permanent rare-earth magnet and high T(sub c) superconducting material versus vertical and lateral displacements were made. A large hysteresis loop results for large displacements, while minor loops result for small displacements. These minor loops seem to give a slope proportional to the magnetic stiffness, and are probably indicative of flux pinning forces. Experiments of rotary speed versus time show a linear decay in a vacuum. Measurements of magnetic dipole over a high-T(sub c) superconducting disc of YBCO show that the lateral vibrations of levitated rotors were measured which indicates that transverse flux motion in the superconductor will create dissipation. As a result of these force measurements, an optimum shape for the superconductor bearing pads which gives good lateral and axial stability was designed. Recent force measurements on melt-quench processed superconductors indicate a substantial increase in levitation force and magnetic stiffness over free sintered materials. As a result, application of high-T(sub c) superconducting bearings are beginning to show great promise at this time.

  5. Sensitivity Enhancement by Exchange Mediated MagnetizationTransfer of the Xenon Biosensor Signal

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Sandra; Chavez, Lana; Lowery, Thomas J.; Han, Song-I.; Wemmer, David E.; Pines, Alexander

    2006-08-31

    Hyperpolarized xenon associated with ligand derivitized cryptophane-A cages has been developed as a NMR based biosensor. To optimize the detection sensitivity we describe use of xenon exchange between the caged and bulk dissolved xenon as an effective signal amplifier. This approach, somewhat analogous to 'remote detection' described recently, uses the chemical exchange to repeatedly transfer spectroscopic information from caged to bulk xenon, effectively integrating the caged signal. After an optimized integration period, the signal is read out by observation of the bulk magnetization. The spectrum of the caged xenon is reconstructed through use of a variable evolution period before transfer and Fourier analysis of the bulk signal as a function of the evolution time.

  6. Stretchable Spin Valve with Stable Magnetic Field Sensitivity by Ribbon-Patterned Periodic Wrinkles.

    Science.gov (United States)

    Li, Huihui; Zhan, Qingfeng; Liu, Yiwei; Liu, Luping; Yang, Huali; Zuo, Zhenghu; Shang, Tian; Wang, Baomin; Li, Run-Wei

    2016-04-26

    A strain-relief structure by combining the strain-engineered periodic wrinkles and the parallel ribbons was employed to fabricate flexible dual spin valves onto PDMS substrates in a direct sputtering method. The strain-relief structure can accommodate the biaxial strain accompanying with stretching operation (the uniaxial applied tensile strain and the induced transverse compressive strain due to the Poisson effect), thus significantly reducing the influence of the residual strain on the giant magnetoresistance (GMR) performance. The fabricated GMR dual spin-valve sensor exhibits the nearly unchanged MR ratio of 9.9%, magnetic field sensitivity up to 0.69%/Oe, and zero-field resistance in a wide range of stretching strain, making it promising for applications on a conformal shape or a movement part.

  7. Repeated amphetamine treatment alters spinal magnetic resonance signals and pain sensitivity in mice.

    Science.gov (United States)

    Lei, Bing-Hsuan; Chen, Jyh-Horng; Yin, Hsiang-Shu

    2014-11-07

    Manganese-enhanced magnetic resonance imaging (MEMRI) has been extensively used in studying the structural and functional features of the central nervous system (CNS). Divalent manganese ion (Mn(2+)) not only enhances MRI contrast, but also enters cells via voltage-gated calcium channels or ionotropic glutamate receptors, which represents an index of neural activities. In the current mouse model, following the repeated amphetamine (Amph) treatment, a reduction of reactivity to thermal pain stimulus was noticed. Since the spinal dorsal horn is the first relay station for pain transmission in CNS, we examined the changes of neural activity in the dorsal spinal cord, particularly the superficial dorsal horn, by analyzing manganese-enhanced T1-weighted MR images (T1WIs). Our data revealed a temporal correlation between reduced pain sensitivity and increased MEMR signals in the spinal dorsal horn subsequent to repeated Amph treatments. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  8. Point sensitive NMR imaging system using a magnetic field configuration with a spatial minimum

    Science.gov (United States)

    Eberhard, P.H.

    A point-sensitive NMR imaging system in which a main solenoid coil produces a relatively strong and substantially uniform magnetic field and a pair of perturbing coils powered by current in the same direction superimposes a pair of relatively weak perturbing fields on the main field to produce a resultant point of minimum field strength at a desired location in a direction along the Z-axis. Two other pairs of perturbing coils superimpose relatively weak field gradients on the main field in directions along the X- and Y-axes to locate the minimum field point at a desired location in a plane normal to the Z-axes. An rf generator irradiates a tissue specimen in the field with radio frequency energy so that desired nuclei in a small volume at the point of minimum field strength will resonate.

  9. Renal ablation using magnetic resonance-guided high intensity focused ultrasound: Magnetic resonance imaging and histopathology assessment

    OpenAIRE

    Saeed, Maythem; Krug, Roland; Do, Loi; Steven W. Hetts; Wilson, Mark W.

    2016-01-01

    AIM: To use magnetic resonance-guided high intensity focused ultrasound (MRg-HIFU), magnetic resonance imaging (MRI) and histopathology for noninvasively ablating, quantifying and characterizing ablated renal tissue.

  10. Magnetically Regulated Gas Accretion in High-Redshift Galactic Disks

    Science.gov (United States)

    Birnboim, Yuval

    2009-09-01

    Disk galaxies are in hydrostatic equilibrium along their vertical axis. The pressure allowing for this configuration consists of thermal, turbulent, magnetic, and cosmic-ray components. For the Milky Way the thermal pressure contributes ~10% of the total pressure near the plane, with this fraction dropping toward higher altitudes. Out of the rest, magnetic fields contribute ~1/3 of the pressure to distances of ~3 kpc above the disk plane. In this Letter, we attempt to extrapolate these local values to high-redshift, rapidly accreting, rapidly star-forming disk galaxies and study the effect of the extra pressure sources on the accretion of gas onto the galaxies. In particular, magnetic field tension may convert a smooth cold-flow accretion to clumpy, irregular star formation regions and rates. The infalling gas accumulates on the edge of the magnetic fields, supported by magnetic tension. When the mass of the infalling gas exceeds some threshold mass, its gravitational force cannot be balanced by magnetic tension anymore, and it falls toward the disk's plane, rapidly making stars. Simplified estimations of this threshold mass are consistent with clumpy star formation observed in SINS, UDF, GOODS, and GEMS surveys. We discuss the shortcomings of pure hydrodynamic codes in simulating the accretion of cold flows into galaxies, and emphasize the need for magnetohydrodynamic simulations.

  11. Pilot Study of Inhaled Aerosols Targeted via Magnetic Alignment of High Aspect Ratio Particles in Rabbits

    Directory of Open Access Journals (Sweden)

    Gillian E. S. Redman

    2011-01-01

    Full Text Available Recently, inhaled pharmaceutical aerosols have seen increased investigation in the treatment of lung cancer, where the inability to deliver adequate therapeutic drug concentrations to tumour sites may be overcome with improved targeted delivery to the site of the tumour. In this study, the feasibility of magnetically targeted delivery of high aspect ratio particles loaded with iron oxide nanoparticles was studied in 19 New Zealand White rabbits. Half of the exposed rabbits had a magnetic field placed externally over their right lung. Iron sensitive magnetic resonance images of the lungs were acquired to determine the iron concentrations in the right and left lung of each animal. The right/left ratio increased in the middle and basal regions of the lung where, due to the morphology of the rabbit lung, this method of targeting is most effective. With further optimization, this technique could be an effective method for increasing the dose of drug delivered to a specific site within the lung.

  12. High Force Magnetic Levitation Using Magnetized Superconducting Bulks as a Field Source for Bearing Applications

    Science.gov (United States)

    Patel, A.; Giunchi, G.; Albisetti, A. Figini; Shi, Y.; Hopkins, S. C.; Palka, R.; Cardwell, D. A.; Glowacki, B. A.

    The ability of high temperature superconducting bulks to trap magnetic fields of several tesla allows them to generate very high levitation force. This paper reports the development of a bulk-bulk superconducting rotary bearing design which uses superconducting bulks on both the rotor and the stator. An evaluation is made of the effectiveness of pulsed fields for magnetizing bulks. Modeling of the bulks using the perfectly trapped flux model is also reported to assess the limits of the bearing design. The results demonstrate the feasibility of a (RE)BCO-MgB2 bulk bearing capable of force densities of the order of 100N/cm2. The design and construction of a unique system capable of magnetizing a 25 mm (RE)BCO bulk and measuring levitation force between this bulk and a coaxial MgB2 hollow cylinder is outlined.

  13. Non-magnetic aspect sensitive auroral echoes from the lower E region observed at 50 MHz

    Directory of Open Access Journals (Sweden)

    R. Rüster

    1999-10-01

    Full Text Available Backscatter from E-region irregularities was observed at aspect angles close to 90° (almost parallel to the direction of the magnetic field using the ALOMAR SOUSY radar at Andoya/Norway. Strong electric fields and increased E-region electron temperatures simultaneously measured with the incoherent scatter facility EISCAT proved that the Farley-Buneman plasma instability was excited. In addition, strong particle precipitation was present as inferred from EISCAT electron densities indicating that the gradient drift instability may have been active, too. Backscatter at such large aspect angles was not expected and has not been observed before. The characteristics of the observed echoes, however, are in many aspects completely different from usual auroral radar results: the Doppler velocities are only of the order of 10 m/s, the half-width of the spectra is around 5 m/s, the echoes originate at altitudes well below 100 km, and they seem to be not aspect-sensitive with respect to the magnetic field direction. We, therefore, conclude that the corresponding irregularities are not caused by the mentioned instabilities and that other mechanism have to be invoked.Key words. Ionosphere (plasma waves and instabilities; ionosphere irregularities; particle precipitaion · Meteorology and atmospheric dynamics (middle atmosphere dynamics

  14. High-sensitivity AMS for heavy nuclides at the Munich Tandem accelerator

    CERN Document Server

    Knie, K; Korschinek, G; Rugel, G; Rühm, W; Wallner, C

    2000-01-01

    During the last years we have aimed at utilizing the high energy achievable at the Munich MP Tandem (TV=14 MV) for maximum sensitivity. One of our interests is the measurements of radionuclides around A=60 ( sup 5 sup 3 Mn, sup 6 sup 0 Fe, sup 6 sup 3 Ni) because of their high scientific potentials. However, in this mass region there are usually strong limitations in sensitivity due to a large isobaric background. Its suppression is performed by means of a gas-filled magnet and a multi DELTA E ionization chamber. A Wien filter and a time-of-flight path allow a further suppression of (non-isobaric) background. The optimization of the setup as a whole yielded detection limits of sup 5 sup 3 Mn/Mn approx 2x10 sup - sup 1 sup 4 sup 6 sup 3 Ni/Ni approx 2x10 sup - sup 1 sup 4 and sup 6 sup 0 Fe/Fe approx 2x10 sup - sup 1 sup 6 , which presently cannot be achieved by any other detection method. The overall efficiency (including ion source) is typically 10 sup - sup 5 -10 sup - sup 4. The gas-filled magnet allows an...

  15. Special-Purpose High-Torque Permanent-Magnet Motors

    Science.gov (United States)

    Doane, George B., III

    1995-01-01

    Permanent-magnet brushless motors that must provide high commanded torques and satisfy unusual heat-removal requirement are developed. Intended for use as thrust-vector-control actuators in large rocket engines. Techniques and concepts used to design improved motors for special terrestrial applications. Conceptual motor design calls for use of rotor containing latest high-energy-product rare-earth permanent magnets so that motor produces required torque while drawing smallest possible currents from power supply. Torque generated by electromagnetic interaction between stator and permanent magnets in rotor when associated electronic circuits applied appropriately temporally and spatially phased currents to stator windings. Phase relationships needed to produce commanded torque computed in response to torque command and to electronically sensed angular position of rotor relative to stator.

  16. High-Energy Electron Confinement in a Magnetic Cusp Configuration

    Directory of Open Access Journals (Sweden)

    Jaeyoung Park

    2015-06-01

    Full Text Available We report experimental results validating the concept that plasma confinement is enhanced in a magnetic cusp configuration when β (plasma pressure/magnetic field pressure is of order unity. This enhancement is required for a fusion power reactor based on cusp confinement to be feasible. The magnetic cusp configuration possesses a critical advantage: the plasma is stable to large scale perturbations. However, early work indicated that plasma loss rates in a reactor based on a cusp configuration were too large for net power production. Grad and others theorized that at high β a sharp boundary would form between the plasma and the magnetic field, leading to substantially smaller loss rates. While not able to confirm the details of Grad’s work, the current experiment does validate, for the first time, the conjecture that confinement is substantially improved at high β. This represents critical progress toward an understanding of the plasma dynamics in a high-β cusp system. We hope that these results will stimulate a renewed interest in the cusp configuration as a fusion confinement candidate. In addition, the enhanced high-energy electron confinement resolves a key impediment to progress of the Polywell fusion concept, which combines a high-β cusp configuration with electrostatic fusion for a compact, power-producing nuclear fusion reactor.

  17. High sensitivity chemically amplified EUV resists through enhanced EUV absorption

    Science.gov (United States)

    Ongayi, Owendi; Christianson, Matthew; Meyer, Matthew; Coley, Suzanne; Valeri, David; Kwok, Amy; Wagner, Mike; Cameron, Jim; Thackeray, Jim

    2012-03-01

    Resolution, line edge roughness, sensitivity and low outgassing are the key focus points for extreme ultraviolet (EUV) resist materials. Sensitivity has become increasingly important so as to address throughput concerns in device manufacturing and compensate for the low power of EUV sources. Recent studies have shown that increasing the polymer linear absorption absorption coefficient in EUV resists translates to higher acid generation efficiency and good pattern formation. In this study, novel high absorbing polymer platforms are evaluated. The contributing effect of the novel absorbing chromophore to the resultant chemically amplified photoresist is evaluated and compared with a standard methacrylate PAG Bound Polymer (PBP) platform. We report that by increasing EUV absorption, we cleanly resolved 17 nm 1:1 line space can be achieved at a sensitivity of 14.5 mJ/cm2, which is consistent with dose requirements dictated by the ITRS roadmap. We also probe the effect of fluorinated small molecule additives on acid yield generation (Dil C) at EUV of a PBP platform.

  18. Interface engineering of a highly sensitive solution processed organic photodiode.

    Science.gov (United States)

    Kim, Yu Jin; Park, Chan Eon; Chung, Dae Sung

    2014-09-14

    We report on tuning of the interfacial properties of a highly sensitive organic photodiode by introducing a buffer layer between the anode and the semiconductor layer. The effects of different buffer layers consisting of a self-assembled monolayer (SAM), PEDOT:PSS, and pentacene on the morphology and crystallinity of the upper-deposited bulk heterojunction semiconductor layer are carefully analyzed combined with electrical analysis. The active layer is controlled to be nearly homogeneous and to have low crystallinity by using a SAM or PEDOT:PSS buffer layers, whereas a highly crystalline morphology is realized by using the pentacene buffer layer. When exposed to light pulses, the external quantum efficiency and thus the photocurrent are slightly higher for the PEDOT:PSS-based photodiode; however the dark current is the lowest for the pentacene-based photodiode. We discuss the origin of the high sensitivity (a detectivity of 1.3 × 10(12) Jones and a linear dynamic range of 95 dB) of the pentacene-based photodiode, particularly in terms of the morphology-driven low dark current.

  19. High Sensitivity Surface Enhanced Raman Scattering Detection of Tryptophan

    Science.gov (United States)

    Kandakkathara, Archana

    Raman spectroscopy has the capability of providing detailed information about molecular structure, but the extremely small cross section of Raman scattering prevents this technique from applications requiring high sensitivity. Surface enhanced Raman scattering (SERS) on the other hand provides strongly increased Raman signal from molecules attached to metallic nanostructures. SERS is thus a promising technique for high sensitivity analytical applications. One particular area of interest is the application of such techniques for the analysis of the composition of biological cells. However, there are issues which have to be addressed in order to make SERS a reliable technique such as the optimization of conditions for any given analyte, understanding the kinetic processes of binding of the target molecules to the nanostructures and understanding the evolution and coagulation of the nanostructures, in the case of colloidal solutions. The latter processes introduce a delay time for the observation of maximum enhancement factors which must be taken into account for any given implementation of SERS. In the present thesis the goal was to develop very sensitive SERS techniques for the measurement of biomolecules of interest for analysis of the contents of cells. The techniques explored could be eventually be applicable to microfluidic systems with the ultimate goal of analyzing the molecular constituents of single cells. SERS study of different amino acids and organic dyes were performed during the course of this thesis. A high sensitivity detection system based on SERS has been developed and spectrum from tryptophan (Trp) amino acid at very low concentration (10-8 M) has been detected. The concentration at which good quality SERS spectra could be detected from Trp is 4 orders of magnitude smaller than that previously reported in literature. It has shown that at such low concentrations the SERS spectra of Trp are qualitatively distinct from the spectra commonly reported in

  20. Magnetoelectric Transverse Gradient Sensor with High Detection Sensitivity and Low Gradient Noise

    Directory of Open Access Journals (Sweden)

    Mingji Zhang

    2017-10-01

    Full Text Available We report, theoretically and experimentally, the realization of a high detection performance in a novel magnetoelectric (ME transverse gradient sensor based on the large ME effect and the magnetic field gradient (MFG technique in a pair of magnetically-biased, electrically-shielded, and mechanically-enclosed ME composites having a transverse orientation and an axial separation. The output voltage of the gradient sensor is directly obtained from the transverse MFG-induced difference in ME voltage between the two ME composites and is calibrated against transverse MFGs to give a high detection sensitivity of 0.4–30.6 V/(T/m, a strong common-mode magnetic field noise rejection rate of <−14.5 dB, a small input-output nonlinearity of <10 ppm, and a low gradient noise of 0.16–620 nT/m/ Hz in a broad frequency range of 1 Hz–170 kHz under a small baseline of 35 mm. An analysis of experimental gradient noise spectra obtained in a magnetically-unshielded laboratory environment reveals the domination of the pink (1/f noise, dielectric loss noise, and power-frequency noise below 3 kHz, in addition to the circuit noise above 3 kHz, in the gradient sensor. The high detection performance, together with the added merit of passive and direct ME conversion by the large ME effect in the ME composites, makes the gradient sensor suitable for the passive, direct, and broadband detection of transverse MFGs.

  1. Experimental Contribution to High Precision Characterization of Magnetic Forces in Active Magnetic Bearings

    DEFF Research Database (Denmark)

    Kjølhede, Klaus; Santos, Ilmar

    2006-01-01

    contribution of the work is the characterization of magnetic forces by using two different experimental approaches. Such approaches are investigated and described in detail. A special test rig is designed where the 4 pole - AMB is able to generate forces up to 1900 N. The high precision characterization...

  2. The truncated driven NOE and 13C NMR sensitivity enhancement in magnetically-aligned bicelles

    Science.gov (United States)

    Macdonald, Peter M.; Soong, Ronald

    2007-09-01

    The truncated driven nuclear Overhauser effect (NOE) sequence is examined as a means of sensitivity enhancement in 13C NMR spectroscopy of magnetically-aligned bicelles consisting of 4.5:1 mixtures of DMPC (1,2-dimyristoyl- sn-glycero-3-phosphocholine) plus DHPC (1,2-dihexanoyl- sn-glycero-3-phosphocholine), with 1 mole% DMPE-PEG 2000 (1,2-dimyristoyl- sn-glycero-3-phosphoethanolamine- N-methoxy(polyethylene glycol)-2000). Steady-state NOE enhancements were observed at all carbon segments except the lipid carbonyls, but full NOE enhancements were obtained only for the most mobile carbon segments, specifically the choline quaternary methyls and terminal acyl chain methyls of both DMPC and DHPC, as well as the ethylene oxide segments of the PEG head group of DMPE-PEG 2000. Other carbon segments exhibited NOE enhancements that scaled with mobility as determined by transient NOE measurements combined with spin-lattice relaxation measurements. We conclude that the truncated driven NOE provides sensitivity enhancement complimentary to that yielded by cross-polarization techniques and for mobile membrane-associated species may be preferred for its robustness and ease of setup.

  3. The truncated driven NOE and (13)C NMR sensitivity enhancement in magnetically-aligned bicelles.

    Science.gov (United States)

    Macdonald, Peter M; Soong, Ronald

    2007-09-01

    The truncated driven nuclear Overhauser effect (NOE) sequence is examined as a means of sensitivity enhancement in (13)C NMR spectroscopy of magnetically-aligned bicelles consisting of 4.5:1 mixtures of DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) plus DHPC (1,2-dihexanoyl-sn-glycero-3-phosphocholine), with 1 mole% DMPE-PEG 2000 (1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine-N-methoxy(polyethylene glycol)-2000). Steady-state NOE enhancements were observed at all carbon segments except the lipid carbonyls, but full NOE enhancements were obtained only for the most mobile carbon segments, specifically the choline quaternary methyls and terminal acyl chain methyls of both DMPC and DHPC, as well as the ethylene oxide segments of the PEG head group of DMPE-PEG 2000. Other carbon segments exhibited NOE enhancements that scaled with mobility as determined by transient NOE measurements combined with spin-lattice relaxation measurements. We conclude that the truncated driven NOE provides sensitivity enhancement complimentary to that yielded by cross-polarization techniques and for mobile membrane-associated species may be preferred for its robustness and ease of setup.

  4. Survey of high field superconducting material for accelerator magnets

    Energy Technology Data Exchange (ETDEWEB)

    Scahlan, R.; Greene, A.F.; Suenaga, M.

    1986-05-01

    The high field superconductors which could be used in accelerator dipole magnets are surveyed, ranking these candidates with respect to ease of fabrication and cost as well as superconducting properties. Emphasis is on Nb/sub 3/Sn and NbTi. 27 refs., 2 figs. (LEW)

  5. Modelling of the magnetic and magnetostrictive properties of high ...

    Indian Academy of Sciences (India)

    This high correspondence of experimental and modelled characteristics is confirmed by the fact that Pearson r2 indicator is surpassing 99%. 4. Modelling of the magnetostrictive properties. In a simplified model, the magnetostriction λ can be calculated from quadratic equation as a function of magnetization M [11]:. Table 1.

  6. National Program on High Field Accelerator Magnet R&D

    Energy Technology Data Exchange (ETDEWEB)

    Apollinari, G. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Cooley, L. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Zlobin, A. V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Caspi, S. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Gourlay, S. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Prestemon, S. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Larbalestier, D. [National High Magnetic Field Laboratory, Tallahassee, FL (United States); Gupta, R. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wanderer, P. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2014-09-26

    A National High-Field Magnet (HFM) Program is proposed as a thrust of the updated DOE-HEP General Accelerator R&D Program. The program responds to Recommendation 24 of the 2014 Particle Physics Project Prioritization Panel (P5) Report.

  7. Self-propagating high temperature synthesis and magnetic ...

    Indian Academy of Sciences (India)

    Ni–Zn ferrite powders were synthesized by self-propagating high temperature synthesis (SHS) method. X-ray diffraction, TEM and vibrating sample magnetometry (VSM) were used to characterize the phase composition, microstructure and magnetic properties of the combustion products. The effect of the combustion ...

  8. Advances in high-gradient magnetic fishing for bioprocessing

    DEFF Research Database (Denmark)

    Goncalves Gomes, Claudia Sofia

    2006-01-01

    High-gradient magnetic fishing” (HGMF) er en metode til processering af fødestrømme med biologiske molekyler. HGMF integrerer brugen af superparamagnetiske adsorbenter med separation og processering med høj-gradient magnetisk separation (HGMS) i et magnetisk filter. Adsorbenterne er uporøse og m...

  9. High pressure-sensitive gene expression in Lactobacillus sanfranciscensis

    Directory of Open Access Journals (Sweden)

    R.F. Vogel

    2005-08-01

    Full Text Available Lactobacillus sanfranciscensis is a Gram-positive lactic acid bacterium used in food biotechnology. It is necessary to investigate many aspects of a model organism to elucidate mechanisms of stress response, to facilitate preparation, application and performance in food fermentation, to understand mechanisms of inactivation, and to identify novel tools for high pressure biotechnology. To investigate the mechanisms of the complex bacterial response to high pressure we have analyzed changes in the proteome and transcriptome by 2-D electrophoresis, and by microarrays and real time PCR, respectively. More than 16 proteins were found to be differentially expressed upon high pressure stress and were compared to those sensitive to other stresses. Except for one apparently high pressure-specific stress protein, no pressure-specific stress proteins were found, and the proteome response to pressure was found to differ from that induced by other stresses. Selected pressure-sensitive proteins were partially sequenced and their genes were identified by reverse genetics. In a transcriptome analysis of a redundancy cleared shot gun library, about 7% of the genes investigated were found to be affected. Most of them appeared to be up-regulated 2- to 4-fold and these results were confirmed by real time PCR. Gene induction was shown for some genes up-regulated at the proteome level (clpL/groEL/rbsK, while the response of others to high hydrostatic pressure at the transcriptome level seemed to differ from that observed at the proteome level. The up-regulation of selected genes supports the view that the cell tries to compensate for pressure-induced impairment of translation and membrane transport.

  10. Magnetic forces in high-T(sub c) superconducting bearings

    Science.gov (United States)

    Moon, F. C.

    1990-01-01

    In September 1987 research at Cornell levitated a small rotor on superconducting bearing at 10,000 rpm. In April 1989 a speed of 120,000 rpm was achieved in a passive bearing with no active control. The bearing material used was YBa2Cu3O7. There is no evidence that the rotation speed has any significant effect on the lift force. Magnetic force measurements between a permanent rare-earth magnet and high T(sub c) superconducting material versus vertical and lateral displacements were made. A large hysteresis loop results for large displacements, while minor loops result for small displacements. These minor loops seem to give a slope proportional to the magnetic stiffness, and are probably indicative of flux pinning forces. Experiments of rotary speed versus time show a linear decay in a vacuum. Measurements of magnetic drag forces of a magnetic dipole over a high-T(sub c) superconducting disc of YBCO show that the drag force reaches a constant value, independent of the speed. Dampling of lateral vibrations of levitated rotors were measured which indicates that transverse flux motion in the superconductor will create dissipation. As a result of these force measurements, an optimum shape for the superconductor bearing pads which gives good lateral and axial stability was designed. Recent force measurements on melt-quench processed superconductors indicate a substantial increase in levitation force and magnetic stiffness over free sintered materials. As a result, application of high-T(sub c) superconducting bearings are beginning to show great promise at this time.

  11. Highly sensitive detection of Staphylococcus aureus directly from patient blood.

    Directory of Open Access Journals (Sweden)

    Padmapriya P Banada

    Full Text Available Rapid detection of bloodstream infections (BSIs can be lifesaving. We investigated the sample processing and assay parameters necessary for highly-sensitive detection of bloodstream bacteria, using Staphylococcus aureus as a model pathogen and an automated fluidic sample processing-polymerase chain reaction (PCR platform as a model diagnostic system.We compared a short 128 bp amplicon hemi-nested PCR and a relatively shorter 79 bp amplicon nested PCR targeting the S. aureus nuc and sodA genes, respectively. The sodA nested assay showed an enhanced limit of detection (LOD of 5 genomic copies per reaction or 10 colony forming units (CFU per ml blood over 50 copies per reaction or 50 CFU/ml for the nuc assay. To establish optimal extraction protocols, we investigated the relative abundance of the bacteria in different components of the blood (white blood cells (WBCs, plasma or whole blood, using the above assays. The blood samples were obtained from the patients who were culture positive for S. aureus. Whole blood resulted in maximum PCR positives with sodA assay (90% positive as opposed to cell-associated bacteria (in WBCs (71% samples positive or free bacterial DNA in plasma (62.5% samples positive. Both the assays were further tested for direct detection of S. aureus in patient whole blood samples that were contemporaneous culture positive. S. aureus was detected in 40/45 of culture-positive patients (sensitivity 89%, 95% CI 0.75-0.96 and 0/59 negative controls with the sodA assay (specificity 100%, 95% CI 0.92-1.We have demonstrated a highly sensitive two-hour assay for detection of sepsis causing bacteria like S. aureus directly in 1 ml of whole blood, without the need for blood culture.

  12. Highly sensitive reduced graphene oxide microelectrode array sensor.

    Science.gov (United States)

    Ng, Andrew M H; Kenry; Teck Lim, Chwee; Low, Hong Yee; Loh, Kian Ping

    2015-03-15

    Reduced graphene oxide (rGO) has been fabricated into a microelectrode array (MEA) using a modified nanoimprint lithography (NIL) technique. Through a modified NIL process, the rGO MEA was fabricated by a self-alignment of conducting Indium Tin Oxide (ITO) and rGO layer without etching of the rGO layer. The rGO MEA consists of an array of 10μm circular disks and microelectrode signature has been found at a pitch spacing of 60μm. The rGO MEA shows a sensitivity of 1.91nAμm(-1) to dopamine (DA) without the use of mediators or functionalization of the reduced graphene oxide (rGO) active layer. The performance of rGO MEA remains stable when tested under highly resistive media using a continuous flow set up, as well as when subjecting it to mechanical stress. The successful demonstration of NIL for fabricating rGO microelectrodes on flexible substrate presents a route for the large scale fabrication of highly sensitive, flexible and thin biosensing platform. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Magnetic liposomes for colorectal cancer cells therapy by high-frequency magnetic field treatment

    Science.gov (United States)

    Hardiansyah, Andri; Huang, Li-Ying; Yang, Ming-Chien; Liu, Ting-Yu; Tsai, Sung-Chen; Yang, Chih-Yung; Kuo, Chih-Yu; Chan, Tzu-Yi; Zou, Hui-Ming; Lian, Wei-Nan; Lin, Chi-Hung

    2014-09-01

    In this study, we developed the cancer treatment through the combination of chemotherapy and thermotherapy using doxorubicin-loaded magnetic liposomes. The citric acid-coated magnetic nanoparticles (CAMNP, ca. 10 nm) and doxorubicin were encapsulated into the liposome (HSPC/DSPE/cholesterol = 12.5:1:8.25) by rotary evaporation and ultrasonication process. The resultant magnetic liposomes ( ca. 90 to 130 nm) were subject to characterization including transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD), zeta potential, Fourier transform infrared (FTIR) spectrophotometer, and fluorescence microscope. In vitro cytotoxicity of the drug carrier platform was investigated through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay using L-929 cells, as the mammalian cell model. In vitro cytotoxicity and hyperthermia (inductive heating) studies were evaluated against colorectal cancer (CT-26 cells) with high-frequency magnetic field (HFMF) exposure. MTT assay revealed that these drug carriers exhibited no cytotoxicity against L-929 cells, suggesting excellent biocompatibility. When the magnetic liposomes with 1 μM doxorubicin was used to treat CT-26 cells in combination with HFMF exposure, approximately 56% cells were killed and found to be more effective than either hyperthermia or chemotherapy treatment individually. Therefore, these results show that the synergistic effects between chemotherapy (drug-controlled release) and hyperthermia increase the capability to kill cancer cells.

  14. A simple, tunable, and highly sensitive radio-frequency sensor.

    Science.gov (United States)

    Cui, Yan; Sun, Jiwei; He, Yuxi; Wang, Zheng; Wang, Pingshan

    2013-08-05

    We report a radio frequency (RF) sensor that exploits tunable attenuators and phase shifters to achieve high-sensitivity and broad band frequency tunability. Three frequency bands are combined to enable sensor operations from ∼20 MHz to ∼38 GHz. The effective quality factor (Qeff ) of the sensor is as high as ∼3.8 × 10(6) with 200 μl of water samples. We also demonstrate the measurement of 2-proponal-water-solution permittivity at 0.01 mole concentration level from ∼1 GHz to ∼10 GHz. Methanol-water solution and de-ionized water are used to calibrate the RF sensor for the quantitative measurements.

  15. Highly sensitive and specific radioimmunoassays for dihydroergotoxine components in plasma

    Energy Technology Data Exchange (ETDEWEB)

    Pradelles, P.; Collignon, F.

    1984-01-01

    The development of three analogous radioimmunoassay (RIA) procedures for dihydroergotoxine components is described. The antisera were produced by immunization of rabbits with immunogens obtained by coupling egg albumin to the indole group of each ergot alkaloid derivative. In each radioimmunoassay, antibodies do not cross-react more than 5% with the two other derivatives. The tracers iodinated with iodine 125 were prepared by the chloramine-T method and purified by thin layer chromatography. Both antibody affinity and high specific radioactivity of tracers allow a sensitive assay (detection limit less than 20 pg/ml) in human plasma. After high performance liquid chromatography of extracted plasma, immunoreactive materials other than those corresponding to the elution of the three dihydroergotoxine components were not detected. Two preliminary pharmacokinetic profiles obtained in dog and human for each derivative are shown.

  16. Development of high sensitive radon detector with electrostatic collection

    Energy Technology Data Exchange (ETDEWEB)

    Nemoto, Machiko [Tokai Univ., Hiratsuka, Kanagawa (Japan). Faculty of Science; Tasaka, Shigeki; Hori, Hidemitsu; Okumura, Kimihiro; Kajita, Takaaki; Takeuchi, Yasuo

    1997-10-01

    One of the main purposes of Super-Kamiokande is the observation of solar neutrinos. The radon concentration in the detector water should be less than about 5 mBq/m{sup 3}, because low energy background events in this experiment are dominated by radon daughters. We developed a high sensitive radon detector with an electrostatic collection method and a PIN photodiode to measure the energy of {alpha} particles from the daughter nuclei of {sup 222}Rn. We constructed a calibration system to study high voltage dependence and absolute humidity dependence of the detector. As a result, the absolute humidity dependence was clearly observed at the region less than 1.6 g/m{sup 3}. The calibration factor at 0.08 g/m{sup 3} was 1.8{+-}0.1 (count/d)/(mBq/m{sup 3}). The detection limit was 13 mBq/m{sup 3} by the Curie`s method. (author)

  17. Brightness of Solar Magnetic Elements As a Function of Magnetic Flux at High Spatial Resolution

    Science.gov (United States)

    Kahil, F.; Riethmüller, T. L.; Solanki, S. K.

    2017-03-01

    We investigate the relationship between the photospheric magnetic field of small-scale magnetic elements in the quiet-Sun (QS) at disk center and the brightness at 214, 300, 313, 388, 397, and 525.02 nm. To this end, we analyzed spectropolarimetric and imaging time series acquired simultaneously by the Imaging Magnetograph eXperiment magnetograph and the SuFI filter imager on board the balloon-borne observatory {{S}}{{UNRISE}} during its first science flight in 2009, with high spatial and temporal resolution. We find a clear dependence of the contrast in the near ultraviolet and the visible on the line-of-sight component of the magnetic field, B LOS, which is best described by a logarithmic model. This function effectively represents the relationship between the Ca ii H-line emission and B LOS and works better than the power-law fit adopted by previous studies. This, along with the high contrast reached at these wavelengths, will help with determining the contribution of small-scale elements in the QS to the irradiance changes for wavelengths below 388 nm. At all wavelengths, including the continuum at 525.40 nm, the intensity contrast does not decrease with increasing B LOS. This result also strongly supports the fact that {{S}}{{UNRISE}} has resolved small strong magnetic field elements in the internetwork, resulting in constant contrasts for large magnetic fields in our continuum contrast at 525.40 nm versus the B LOS scatterplot, unlike the turnover obtained in previous observational studies. This turnover is due to the intermixing of the bright magnetic features with the dark intergranular lanes surrounding them.

  18. Dynamo Enhancement and Mode Selection Triggered by High Magnetic Permeability

    Science.gov (United States)

    Kreuzahler, S.; Ponty, Y.; Plihon, N.; Homann, H.; Grauer, R.

    2017-12-01

    We present results from consistent dynamo simulations, where the electrically conducting and incompressible flow inside a cylinder vessel is forced by moving impellers numerically implemented by a penalization method. The numerical scheme models jumps of magnetic permeability for the solid impellers, resembling various configurations tested experimentally in the von Kármán sodium experiment. The most striking experimental observations are reproduced in our set of simulations. In particular, we report on the existence of a time-averaged axisymmetric dynamo mode, self-consistently generated when the magnetic permeability of the impellers exceeds a threshold. We describe a possible scenario involving both the turbulent flow in the vicinity of the impellers and the high magnetic permeability of the impellers.

  19. Magnetization Measurements of High-Jc Nb3Sn strands

    CERN Document Server

    Bordini, B; Alknes, P; Ballarino, A; Bottura, L; Oberli, L

    2013-01-01

    High critical current density Nb3Sn wires (Jc > 2500 A/mm2 at 4.2 K and 12 T) are the conductors considered for next generation accelerator magnets. At present, the large magnetization of these strands is a concern within the scientific community because of the impact it might have on the magnet field quality. In order to characterize the magnetic behavior of these wires, an extensive campaign of magnetization measurements was launched at CERN. Powder In Tube (PIT) strands by Bruker-EAS and Restacked Rod Process (RRP®) strands by Oxford Superconducting Technology (OST) were measured between 0 T and 10.5 T at different temperatures (ranging from 1.9 K to 14.5 K). The samples, based on strands with different sub-elements dimensions (35 to 80 μm), were measured with a Vibrating Sample Magnetometer (VSM). The experimental data were analyzed to: 1) calculate the effective filament size and the optimal parameters for the pinning force scaling law; 2) define the field-temperature region where there are flux...

  20. High temperature superconducting axial field magnetic coupler: realization and test

    Science.gov (United States)

    Belguerras, L.; Mezani, S.; Lubin, T.; Lévêque, J.; Rezzoug, A.

    2015-09-01

    Contactless torque transmission through a large airgap is required in some industrial applications in which hermetic isolation is necessary. This torque transmission usually uses magnetic couplers, whose dimension strongly depends on the airgap flux density. The use of high temperature superconducting (HTS) coils to create a strong magnetic field may constitute a solution to reduce the size of the coupler. It is also possible to use this coupler to replace a torque tube in transmitting the torque produced by a HTS motor to its load. This paper presents the detailed construction and tests of an axial field HTS magnetic coupler. Pancake coils have been manufactured from BSCCO tape and used in one rotor of the coupler. The second rotor is mainly composed of NdFeB permanent magnets. Several tests have been carried out showing that the constructed coupler is working properly. A 3D finite element (FE) model of the studied coupler has been developed. Airgap magnetic field and torque measurements have been carried out and compared to the FE results. It has been shown that the measured and the computed quantities are in satisfactory agreement.

  1. Highly magnetic Co nanoparticles fabricated by X-ray radiolysis

    Science.gov (United States)

    Clifford, Dustin M.; Castano, Carlos E.; Rojas, Jessika V.

    2018-03-01

    Advanced routes for the synthesis of nanomaterials, such as ferromagnetic nanoparticles, are being explored that are easy to perform using cost-effective and non-toxic precursors. Radiolytic syntheses based on the use of X-rays as ionizing radiation are promising towards this effort. X-rays were used to produce highly magnetic cobalt nanoparticles (NPs), stable in air up to 200 °C, from the radiolysis of water. Crystal structure analysis by XRD indicates a mixture of Cofcc, 63%, and Cohcp, 37%, phases. Magnetic analysis by VSM gave a saturation magnetization (Ms) 136 emu/g at 1 T and coercivity (Hc) = 325 Oe when the reaction solution was purged with N2 while an air-purged treatment resulted in Co NPs having 102 emu/g with a coercivity (Hc) 270 Oe. Overall, the reduction of Co2+ occurred in an aqueous reaction environment without addition of chemical reductants resulting in Co NPs with size distribution from 20 to 140 nm. This clean approach at ambient temperature produced highly magnetic Co NPs that may be used for switching devices (i.e. reed switches) or as additives for alloys that require high Curie points.

  2. DR 21(OH): A HIGHLY FRAGMENTED, MAGNETIZED, TURBULENT DENSE CORE

    Energy Technology Data Exchange (ETDEWEB)

    Girart, J. M.; Frau, P. [Institut de Ciencies de l' Espai, (CSIC-IEEC), Campus UAB, Facultat de Ciencies, C5p 2, E-08193 Bellaterra, Catalonia (Spain); Zhang, Q. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Koch, P. M.; Tang, Y.-W.; Lai, S.-P.; Ho, P. T. P. [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 10617, Taiwan (China); Qiu, K., E-mail: girart@ice.cat [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)

    2013-07-20

    We present high angular resolution observations of the massive star-forming core DR21(OH) at 880 {mu}m using the Submillimeter Array (SMA). The dense core exhibits an overall velocity gradient in a Keplerian-like pattern, which breaks at the center of the core where SMA 6 and SMA 7 are located. The dust polarization shows a complex magnetic field, compatible with a toroidal configuration. This is in contrast with the large, parsec-scale filament that surrounds the core, where there is a smooth magnetic field. The total magnetic field strengths in the filament and in the core are 0.9 and 2.1 mG, respectively. We found evidence of magnetic field diffusion at the core scales, far beyond the expected value for ambipolar diffusion. It is possible that the diffusion arises from fast magnetic reconnection in the presence of turbulence. The dynamics of the DR 21(OH) core appear to be controlled energetically in equal parts by the magnetic field, magnetohydrodynamic turbulence, and the angular momentum. The effect of the angular momentum (this is a fast rotating core) is probably causing the observed toroidal field configuration. Yet, gravitation overwhelms all the forces, making this a clear supercritical core with a mass-to-flux ratio of {approx_equal} 6 times the critical value. However, simulations show that this is not enough for the high level of fragmentation observed at 1000 AU scales. Thus, rotation and outflow feedback are probably the main causes of the observed fragmentation.

  3. Influence of Magnetic Field on the Mesoporous Structure of Fe-Cu Compounds in Dye-Sensitized Photovoltaic Cells

    Science.gov (United States)

    Alami, Abdul Hai; Zhang, Di; Aokal, Camilia; Abed, Jehad; Abdoun, Ideisan Abu; Alawadhi, Hussain

    2016-03-01

    This paper investigates the effect of applying static and dynamic magnetic fields on the deposition of Fe-Cu compound on the working electrode of a dye-sensitized solar cell. The deposition of this compound on glass is complicated due to the fact that it cannot be evaporated or sintered beyond the dissociation temperature of 973 K (700 °C), and the doctor blade technique causes detrimental layer inconsistencies. The Fe-Cu compound is relatively easy to produce and is significantly cheaper and more absorptive (>81 pct) in the Vis-NIR than the standard TiO2 mesoporous material used for solar cells. It also behaves as a semiconductor due to the high diffusion of the Fe into the Cu lattice that a bandgap of 1.8 eV is obtained. The use of a Schiff base dye with a compatible bandgap of 1.68 eV is used as a sensitizer for the production of a test cell that generated more photocurrent than its TiO2 counterpart, which is a promising result for an alternative mesoporous layer in solar cells.

  4. Combining isothermal rolling circle amplification and electrochemiluminescence for highly sensitive point mutation detection

    Science.gov (United States)

    Su, Qiang; Zhou, Xiaoming

    2008-12-01

    Many pathogenic and genetic diseases are associated with changes in the sequence of particular genes. We describe here a rapid and highly efficient assay for the detection of point mutation. This method is a combination of isothermal rolling circle amplification (RCA) and high sensitive electrochemluminescence (ECL) detection. In the design, a circular template generated by ligation upon the recognition of a point mutation on DNA targets was amplified isothermally by the Phi29 polymerase using a biotinylated primer. The elongation products were hybridized with tris (bipyridine) ruthenium (TBR)-tagged probes and detected in a magnetic bead based ECL platform, indicating the mutation occurrence. P53 was chosen as a model for the identification of this method. The method allowed sensitive determination of the P53 mutation from wild-type and mutant samples. The main advantage of RCA-ECL is that it can be performed under isothermal conditions and avoids the generation of false-positive results. Furthermore, ECL provides a faster, more sensitive, and economical option to currently available electrophoresis-based methods.

  5. New application of superconductors: High sensitivity cryogenic light detectors

    Energy Technology Data Exchange (ETDEWEB)

    Cardani, L., E-mail: laura.cardani@roma1.infn.it [Dipartimento di Fisica, Sapienza Università di Roma, Piazzale Aldo Moro 2, 00185 Roma (Italy); Physics Department, Princeton University, Washington Road, 08544 Princeton, NJ (United States); Bellini, F.; Casali, N. [Dipartimento di Fisica, Sapienza Università di Roma, Piazzale Aldo Moro 2, 00185 Roma (Italy); INFN – Sezione di Roma, Piazzale Aldo Moro 2, 00185 Roma, Italy (Italy); Castellano, M.G. [Istituto di Fotonica e Nanotecnologie – CNR, Via Cineto Romano 42, 00156 Roma (Italy); Colantoni, I.; Coppolecchia, A. [Dipartimento di Fisica, Sapienza Università di Roma, Piazzale Aldo Moro 2, 00185 Roma (Italy); Cosmelli, C.; Cruciani, A. [Dipartimento di Fisica, Sapienza Università di Roma, Piazzale Aldo Moro 2, 00185 Roma (Italy); INFN – Sezione di Roma, Piazzale Aldo Moro 2, 00185 Roma, Italy (Italy); D' Addabbo, A. [INFN – Laboratori Nazionali del Gran Sasso, Assergi (L' Aquila) 67010 (Italy); Di Domizio, S. [INFN – Sezione di Genova, Via Dodecaneso 33, 16146 Genova (Italy); Dipartimento di Fisica, Università degli Studi di Genova, Via Dodecaneso 33, 16146 Genova (Italy); Martinez, M. [Dipartimento di Fisica, Sapienza Università di Roma, Piazzale Aldo Moro 2, 00185 Roma (Italy); INFN – Sezione di Roma, Piazzale Aldo Moro 2, 00185 Roma, Italy (Italy); Laboratorio de Fisica Nuclear y Astroparticulas, Universidad de Zaragoza, Zaragoza 50009 (Spain); Tomei, C. [INFN – Sezione di Roma, Piazzale Aldo Moro 2, 00185 Roma, Italy (Italy); and others

    2017-02-11

    In this paper we describe the current status of the CALDER project, which is developing ultra-sensitive light detectors based on superconductors for cryogenic applications. When we apply an AC current to a superconductor, the Cooper pairs oscillate and acquire kinetic inductance, that can be measured by inserting the superconductor in a LC circuit with high merit factor. Interactions in the superconductor can break the Cooper pairs, causing sizable variations in the kinetic inductance and, thus, in the response of the LC circuit. The continuous monitoring of the amplitude and frequency modulation allows to reconstruct the incident energy with excellent sensitivity. This concept is at the basis of Kinetic Inductance Detectors (KIDs) that are characterized by natural aptitude to multiplexed read-out (several sensors can be tuned to different resonant frequencies and coupled to the same line), resolution of few eV, stable behavior over a wide temperature range, and ease in fabrication. We present the results obtained by the CALDER collaboration with 2×2 cm{sup 2} substrates sampled by 1 or 4 Aluminum KIDs. We show that the performances of the first prototypes are already competitive with those of other commonly used light detectors, and we discuss the strategies for a further improvement.

  6. Luminescent Lanthanide Reporters for High-Sensitivity Novel Bioassays

    Energy Technology Data Exchange (ETDEWEB)

    Anstey, Mitchell R. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Fruetel, Julia A. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Foster, Michael E. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Hayden, Carl C. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Buckley, Heather L. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Arnold, John [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2013-09-01

    Biological imaging and assay technologies rely on fluorescent organic dyes as reporters for a number of interesting targets and processes. However, limitations of organic dyes such as small Stokes shifts, spectral overlap of emission signals with native biological fluorescence background, and photobleaching have all inhibited the development of highly sensitive assays. To overcome the limitations of organic dyes for bioassays, we propose to develop lanthanide-based luminescent dyes and demonstrate them for molecular reporting applications. This relatively new family of dyes was selected for their attractive spectral and chemical properties. Luminescence is imparted by the lanthanide atom and allows for relatively simple chemical structures that can be tailored to the application. The photophysical properties offer unique features such as narrow and non-overlapping emission bands, long luminescent lifetimes, and long wavelength emission, which enable significant sensitivity improvements over organic dyes through spectral and temporal gating of the luminescent signal.Growth in this field has been hindered due to the necessary advanced synthetic chemistry techniques and access to experts in biological assay development. Our strategy for the development of a new lanthanide-based fluorescent reporter system is based on chelation of the lanthanide metal center using absorbing chromophores. Our first strategy involves "Click" chemistry to develop 3-fold symmetric chelators and the other involves use of a new class of tetrapyrrole ligands called corroles. This two-pronged approach is geared towards the optimization of chromophores to enhance light output.

  7. A highly sensitive fiber Bragg grating diaphragm pressure transducer

    Science.gov (United States)

    Allwood, Gary; Wild, Graham; Lubansky, Alex; Hinckley, Steven

    2015-10-01

    In this work, a novel diaphragm based pressure transducer with high sensitivity is described, including the physical design structure, in-depth analysis of optical response to changes in pressure, and a discussion of practical implementation and limitations. A flat circular rubber membrane bonded to a cylinder forms the body of the transducer. A fiber Bragg grating bonded to the center of the diaphragm structure enables the fractional change in pressure to be determined by analyzing the change in Bragg wavelength of the reflected spectra. Extensive evaluation of the physical properties and optical characteristics of the transducer has been performed through experimentation, and modeling using small deformation theory. The results show the transducer has a sensitivity of 0.116 nm/kPa, across a range of 15 kPa. Ultra-low cost interrogation of the optical signal was achieved through the use of an optically mismatched Bragg grating acting as an edge filter to convert the spectral change into an intensity change. A numerical model of the intensity based interrogation was implemented in order to validate the experimental results. Utilizing this interrogation technique and housing both the sensing and reference Bragg gratings within the main body of the transducer means it is effectively temperature insensitive and easily connected to electronic systems.

  8. Sensitivity of once-shocked, weathered high explosives

    Energy Technology Data Exchange (ETDEWEB)

    Williams, K.L.; Harris, B.W.

    1998-07-01

    Effects caused by stimulating once-shocked, weathered high explosives (OSW-HE) are investigated. The sensitivity of OSW-HE to mechanical stimuli was determined using standard industry tests. Some initial results are given. Pieces of OSW-HE were collected from active and inactive firing sites and from an area surrounding a drop tower at Los Alamos where skid and spigot tests were done. Samples evaluated were cast explosives or plastic bonded explosive (PBX) formulations containing cyclotrimethylenetrinitramine (RDX), cyclotetramethylene tetranitramine (HMX), 2,4,6-trinitrotoluene (TNT), mock or inert HE [tris(beta-chloroethyl)phosphate (CEF)], barium nitrate, cyanuric acid, talc, and Kel-F. Once-shocked, weathered LX-10 Livermore explosive [HMX/Viton A, (95/5 wt %)], PBX 9011 [HMX/Estane, (90/10 wt %)], PBX 9404 [HMX/nitrocellulose, tris(beta-chloroethyl) phosphate, (94/3/3 wt %)], Composition B or cyclotol (TNT/RDX explosives), and PBX 9007 (90% RDX, 9.1% styrene, 0.5% dioctyl phthalate, and 0.45 resin) were subjected to the hammer test, the drop-weight impact sensitivity test, differential thermal analysis (DTA), the spark test, the Henkin`s critical temperature test, and the flame test. Samples were subjected to remote, wet cutting and drilling; remote, liquid-nitrogen-cooled grinding and crushing; and scanning electron microscope (SEM) surface analyses for morphological changes.

  9. Multiband multislab 3D time-of-flight magnetic resonance angiography for reduced acquisition time and improved sensitivity.

    NARCIS (Netherlands)

    Schulz, J.; Boyacioǧlu, R.; Norris, David Gordon

    2016-01-01

    Purpose: To explore the use of multiband (MB) imaging in multislab (MS) 3D time-of-flight-magnetic resonance angiography (TOF-MRA) and to improve acquisition time efficiency (TA), inflow contrast and sensitivity in vessel detection. Theory and Methods: TOF-MRA is commonly used for imaging

  10. A new support structure for high field magnets

    CERN Document Server

    Hafalia, R R; Caspi, S; Dietderich, D R; Gourlay, S A; Hannaford, R; Lietzke, A F; Liggins, N; McInturff, A D; Sabbi, G L; Scanlan, R M; O'Neill, J; Swanson, J H

    2002-01-01

    Pre-stress of superconducting magnets can be applied directly through the magnet yoke structure. We have replaced the collar functionality in our 14 Tesla R&D Nb//3Sn dipole magnets with an assembly procedure based on an aluminum shell and bladders. Bladders, placed between the coil pack and surrounding yoke inside the shell, are pressurized up to 10 ksi left bracket 70 MPa right bracket to create an interference gap. Keys placed into the interference gap replace the bladder functionality. Following the assembly, the bladders are deflated and removed. Strain gauges mounted directly on the shell are used to monitor the stress of the entire magnet structure, thereby providing a high degree of pre-stress control without the need for high tolerances. During assembly, a force of 8.2 multiplied by 10**5 lbs /ft left bracket 12 MN/m right bracket is generated by the bladders and the stress in the 1.57 double prime left bracket 40 mm right bracket aluminum shell reaches 20.3 ksi left bracket 140 MPa right bracket...

  11. Shear-driven dynamo waves at high magnetic Reynolds number.

    Science.gov (United States)

    Tobias, S M; Cattaneo, F

    2013-05-23

    Astrophysical magnetic fields often display remarkable organization, despite being generated by dynamo action driven by turbulent flows at high conductivity. An example is the eleven-year solar cycle, which shows spatial coherence over the entire solar surface. The difficulty in understanding the emergence of this large-scale organization is that whereas at low conductivity (measured by the magnetic Reynolds number, Rm) dynamo fields are well organized, at high Rm their structure is dominated by rapidly varying small-scale fluctuations. This arises because the smallest scales have the highest rate of strain, and can amplify magnetic field most efficiently. Therefore most of the effort to find flows whose large-scale dynamo properties persist at high Rm has been frustrated. Here we report high-resolution simulations of a dynamo that can generate organized fields at high Rm; indeed, the generation mechanism, which involves the interaction between helical flows and shear, only becomes effective at large Rm. The shear does not enhance generation at large scales, as is commonly thought; instead it reduces generation at small scales. The solution consists of propagating dynamo waves, whose existence was postulated more than 60 years ago and which have since been used to model the solar cycle.

  12. Pelvic endometriosis: a comparison between low-field (0.2 T) and high-field (1.5 T) magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Minaif, Karine; Ajzen, Sergio [Universidade Federal de Sao Paulo (UNIFESP/EPM), SP (Brazil). Dept. of Imaging Diagnosis]. E-mail: kminaif@uol.com.br; Shigueoka, David Carlos; Minami, Cintia Cristina Satie; Sales, Danilo Moulin; Szejnfeld, Jacob [Universidade Federal de Sao Paulo (UNIFESP/EPM), SP (Brazil). Dept. of Imaging Diagnosis. Unit of Abdomen; Ruano, Jose Maria Cordeiro [Universidade Federal de Sao Paulo (UNIFESP/EPM), SP (Brazil). Dept. of General Gynecology. Sector of Videlaparoscopy; Noguti, Alberto Sinhiti [Universidade Federal de Sao Paulo (UNIFESP/EPM), SP (Brazil). Dept. of General Gynecology

    2008-11-15

    Objective: to compare low-field (0.2 T) with high-field (1.5 T) magnetic resonance imaging in the assessment of pelvic endometriosis and adenomyosis. Materials and methods: twenty-seven female patients with clinically suspected endometriosis were prospectively evaluated by means of high-field and low-field magnetic resonance imaging. The reading of the images was performed by a single radiologist, initiating by the low-field, followed by the high-field images. High-field magnetic resonance imaging was utilized as the golden-standard. Results: among the 27 patients included in the present study, 18 (66.7%) had some type of lesion suggesting the presence of endometriosis demonstrated at high-field images. In 14 of these patients the diagnosis was correctly established by low-field magnetic resonance imaging. Endometriomas, tubal lesions, and endometriotic foci > 7 mm identified at the high-field images were also identified at low-field images with 100% accuracy, sensitivity and specificity. Among the nine patients diagnosed with adenomyosis by high-field images, eight were correctly diagnosed by low-field images with 88.9% accuracy, specificity and sensitivity. Conclusion: low-field magnetic resonance imaging demonstrated a low sensitivity in the detection of small endometriotic foci, high sensitivity in the detection of endometriomas and large endometriotic foci, and high accuracy in the detection of adenomyosis when compared with high-field magnetic resonance imaging. (author)

  13. Magnetic resonance imaging and spectroscopy at ultra high fields

    Energy Technology Data Exchange (ETDEWEB)

    Neuberger, Thomas

    2009-06-23

    The goal of the work presented in this thesis was to explore the possibilities and limitations of MRI / MRS using an ultra high field of 17.6 tesla. A broad range of specific applications and MR methods, from MRI to MRSI and MRS were investigated. The main foci were on sodium magnetic resonance spectroscopic imaging of rodents, magnetic resonance spectroscopy of the mouse brain, and the detection of small amounts of iron labeled stem cells in the rat brain using MRI Sodium spectroscopic imaging was explored since it benefits tremendously from the high magnetic field. Due to the intrinsically low signal in vivo, originating from the low concentrations and short transverse relaxation times, only limited results have been achieved by other researchers until now. Results in the literature include studies conducted on large animals such as dogs to animals as small as rats. No studies performed on mice have been reported, despite the fact that the mouse is the most important laboratory animal due to the ready availability of transgenic strains. Hence, this study concentrated on sodium MRSI of small rodents, mostly mice (brain, heart, and kidney), and in the case of the brain on young rats. The second part of this work concentrated on proton magnetic resonance spectroscopy of the rodent brain. Due to the high magnetic field strength not only the increasing signal but also the extended spectral resolution was advantageous for such kind of studies. The difficulties/limitations of ultra high field MRS were also investigated. In the last part of the presented work detection limits of iron labeled stem cells in vivo using magnetic resonance imaging were explored. The studies provided very useful benchmarks for future researchers in terms of the number of labeled stem cells that are required for high-field MRI studies. Overall this work has shown many of the benefits and the areas that need special attention of ultra high fields in MR. Three topics in MRI, MRS and MRSI were

  14. High efficiency solid-state sensitized heterojunction photovoltaic device

    KAUST Repository

    Wang, Mingkui

    2010-06-01

    The high molar extinction coefficient heteroleptic ruthenium dye, NaRu(4,4′-bis(5-(hexylthio)thiophen-2-yl)-2,2′-bipyridine) (4-carboxylic acid-4′-carboxylate-2,2′-bipyridine) (NCS) 2, exhibits certified 5% electric power conversion efficiency at AM 1.5 solar irradiation (100 mW cm-2) in a solid-state dye-sensitized solar cell using 2,2′,7,7′-tetrakis-(N,N-di-pmethoxyphenylamine)-9, 9′-spirobifluorene (spiro-MeOTAD) as the organic hole-transporting material. This demonstration elucidates a class of photovoltaic devices with potential for low-cost power generation. © 2010 Elsevier Ltd. All rights reserved.

  15. Highly Sensitive Filter Paper Substrate for SERS Trace Explosives Detection

    Directory of Open Access Journals (Sweden)

    Pedro M. Fierro-Mercado

    2012-01-01

    Full Text Available We report on a novel and extremely low-cost surface-enhanced Raman spectroscopy (SERS substrate fabricated depositing gold nanoparticles on common lab filter paper using thermal inkjet technology. The paper-based substrate combines all advantages of other plasmonic structures fabricated by more elaborate techniques with the dynamic flexibility given by the inherent nature of the paper for an efficient sample collection, robustness, and stability. We describe the fabrication, characterization, and SERS activity of our substrate using 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, and 1,3,5-trinitrobenzene as analytes. The paper-based SERS substrates presented a high sensitivity and excellent reproducibility for analytes employed, demonstrating a direct application in forensic science and homeland security.

  16. A SERS biosensor with magnetic substrate CoFe2O4@Ag for sensitive detection of Hg2+

    Science.gov (United States)

    Yang, Xia; He, Yi; Wang, Xueling; Yuan, Ruo

    2017-09-01

    Mercuric ion (Hg2+) is one toxic metal ion existed in aquatic ecosystems which would seriously damage human central nervous system and other organs. So developing an approach to sensitively detect Hg2+ in our living environment is urgent and important. In this work, a novel surface enhancement Raman spectrum(SERS) sensor is fabricated for high selective and ultrasensitive detection of Hg2+ in aqueous solution, based on a stable thymine-Hg2+-thymine (T-Hg2+-T) structure and the π-π interaction between single-stranded DNA (ssDNA) and single walled carbon nanotubes (SWCNTs). Herein, SWCNTs act as Raman labels to produce characteristic Raman peaks which can be a beacon to quantitative detect Hg2+. In the presence of Hg2+, the ssDNA can capture Hg2+ forming T-Hg2+-T structure, which makes SWCNTs leave the hot spots of the SERS-based biosensor. With this design, the Raman intensity of SWCNTs decreased with the increasing concentration of Hg2+. At the same time, CoFe2O4@Ag as active SERS substrates can effectively enhance sensitivity and uniformity of the biosensor through aggregation by magnet. Under optimal conditions, this proposed biosensor can detect Hg2+ at a range from 1 pM to 100 nM with a detection limit of 0.84 pM. With the advantages of good sensitivity, selectivity, simplicity and rapidity, the biosensor is potentially suitable for monitoring of Hg2+ in environmental applications.

  17. Colorimetry and SERS dual-mode detection of telomerase activity: combining rapid screening with high sensitivity

    Science.gov (United States)

    Zong, Shenfei; Wang, Zhuyuan; Chen, Hui; Hu, Guohua; Liu, Min; Chen, Peng; Cui, Yiping

    2014-01-01

    As an important biomarker and therapeutic target, telomerase has attracted considerable attention concerning its detection and monitoring. Here, we present a colorimetry and surface enhanced Raman scattering (SERS) dual-mode telomerase activity detection method, which has several distinctive advantages. First, colorimetric functionality allows rapid preliminary discrimination of telomerase activity by the naked eye. Second, the employment of SERS technique results in greatly improved detection sensitivity. Third, the combination of colorimetry and SERS into one detection system can ensure highly efficacious and sensitive screening of numerous samples. Besides, the avoidance of polymerase chain reaction (PCR) procedures further guarantees fine reliability and simplicity. Generally, the presented method is realized by an ``elongate and capture'' procedure. To be specific, gold nanoparticles modified with Raman molecules and telomeric repeat complementary oligonucleotide are employed as the colorimetric-SERS bifunctional reporting nanotag, while magnetic nanoparticles functionalized with telomerase substrate oligonucleotide are used as the capturing substrate. Telomerase can synthesize and elongate telomeric repeats onto the capturing substrate. The elongated telomeric repeats subsequently facilitate capturing of the reporting nanotag via hybridization between telomeric repeat and its complementary strand. The captured nanotags can cause a significant difference in the color and SERS intensity of the magnetically separated sediments. Thus both the color and SERS can be used as indicators of the telomerase activity. With fast screening ability and outstanding sensitivity, we anticipate that this method would greatly promote practical application of telomerase-based early-stage cancer diagnosis.As an important biomarker and therapeutic target, telomerase has attracted considerable attention concerning its detection and monitoring. Here, we present a colorimetry and

  18. Laser-engraved carbon nanotube paper for instilling high sensitivity, high stretchability, and high linearity in strain sensors

    KAUST Repository

    Xin, Yangyang

    2017-06-29

    There is an increasing demand for strain sensors with high sensitivity and high stretchability for new applications such as robotics or wearable electronics. However, for the available technologies, the sensitivity of the sensors varies widely. These sensors are also highly nonlinear, making reliable measurement challenging. Here we introduce a new family of sensors composed of a laser-engraved carbon nanotube paper embedded in an elastomer. A roll-to-roll pressing of these sensors activates a pre-defined fragmentation process, which results in a well-controlled, fragmented microstructure. Such sensors are reproducible and durable and can attain ultrahigh sensitivity and high stretchability (with a gauge factor of over 4.2 × 10(4) at 150% strain). Moreover, they can attain high linearity from 0% to 15% and from 22% to 150% strain. They are good candidates for stretchable electronic applications that require high sensitivity and linearity at large strains.

  19. Complementary analyses of hollow cylindrical unioriented permanent magnet (HCM) with high permeability external layer.

    Science.gov (United States)

    Lobo, Carlos M S; Tosin, Giancarlo; Baader, Johann E; Colnago, Luiz A

    2017-10-01

    In this article, several studies based on analytical expressions and computational simulations on Hollow Cylindrical Magnets with an external soft ferromagnetic material (HCM magnets) are presented. Electromagnetic configurations, as well as permanent-magnet-based structures, are studied in terms of magnetic field strength and homogeneity. Permanent-magnet-based structures are further analyzed in terms of the anisotropy of the magnetic permeability. It was found that the HCM magnets produce a highly homogeneous magnetic field as long as the magnetic material is isotropic. The dependency of the magnetic field strength and homogeneity in terms of the anisotropy of the magnetic permeability is also explored here. These magnets can potentially be used in medium-resolution NMR spectrometers and high-field NMR spectrometers. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. submitter A High Precision 3D Magnetic Field Scanner for Small to Medium Size Magnets

    CERN Document Server

    Bergsma, F; Garnier, F; Giudici, P A

    2016-01-01

    A bench to measure the magnetic field of small to-medium-sized magnets with high precision was built. It uses a small-sized head with three orthogonal Hall probes, supported on a long pole at continuous movement during measurement. The head is calibrated in three dimensions by rotation over the full solid angle in a special device. From 0 to 2.5 T, the precision is ±0.2 mT in all components. The spatial range is 1 × 1 × 2 m with precision of ±0.02 mm. The bench and its controls are lightweight and easy to transport. The head can penetrate through small apertures and measure as close as 0.5 mm from the surface of a magnet. The bench can scan complicated grids in Cartesian or cylindrical coordinates, steered by a simple text file on an accompanying PC. The raw data is online converted to magnetic units and stored in a text file.

  1. Output Enhancement Effect of Magnetic Underlayer in High-Density Magnetic Recording

    Science.gov (United States)

    Endo, Katsumi; Yoshida, Osamu; Sasaki, Kenji; Nakayama, Kazuhiko; Maki, Kazuo; Nakamura, Yoshihisa

    1999-10-01

    A double-layered tape with a metal particulate (MP) upper layer and a metal-evaporated (ME) underlayer is fabricated. Output properties were enhanced over the single-layered MP tape in high-density recording. This effect cannot be explained by conventional magnetic recording mechanisms, and a new model of magneto-static interaction is proposed. This model is supported by a preliminary computer simulation.

  2. Time-resolved optical absorption microspectroscopy of magnetic field sensitive flavin photochemistry.

    Science.gov (United States)

    Antill, Lewis M; Beardmore, Joshua P; Woodward, Jonathan R

    2018-02-01

    The photochemical reactions of blue-light receptor proteins have received much attention due to their very important biological functions. In addition, there is also growing evidence that the one particular class of such proteins, the cryptochromes, may be associated with not only a biological photo-response but also a magneto-response, which may be responsible for the mechanism by which many animals can respond to the weak geomagnetic field. Therefore, there is an important scientific question over whether it is possible to directly observe such photochemical processes, and indeed the effects of weak magnetic fields thereon, taking place both in purified protein samples in vitro and in actual biochemical cells and tissues. For the former samples, the key lies in being able to make sensitive spectroscopic measurements on very small volumes of samples at potentially low protein concentrations, while the latter requires, in addition, spatially resolved measurements on length scales smaller than typical cellular components, i.e., sub-micron resolution. In this work, we discuss a two- and three-color confocal pump-probe microscopic approach to this question which satisfies these requirements and is thus useful for experimental measurements in both cases.

  3. Functional Polymers in Protein Detection Platforms: Optical, Electrochemical, Electrical, Mass-Sensitive, and Magnetic Biosensors

    Science.gov (United States)

    Hahm, Jong-in

    2011-01-01

    The rapidly growing field of proteomics and related applied sectors in the life sciences demands convenient methodologies for detecting and measuring the levels of specific proteins as well as for screening and analyzing for interacting protein systems. Materials utilized for such protein detection and measurement platforms should meet particular specifications which include ease-of-mass manufacture, biological stability, chemical functionality, cost effectiveness, and portability. Polymers can satisfy many of these requirements and are often considered as choice materials in various biological detection platforms. Therefore, tremendous research efforts have been made for developing new polymers both in macroscopic and nanoscopic length scales as well as applying existing polymeric materials for protein measurements. In this review article, both conventional and alternative techniques for protein detection are overviewed while focusing on the use of various polymeric materials in different protein sensing technologies. Among many available detection mechanisms, most common approaches such as optical, electrochemical, electrical, mass-sensitive, and magnetic methods are comprehensively discussed in this article. Desired properties of polymers exploited for each type of protein detection approach are summarized. Current challenges associated with the application of polymeric materials are examined in each protein detection category. Difficulties facing both quantitative and qualitative protein measurements are also identified. The latest efforts on the development and evaluation of nanoscale polymeric systems for improved protein detection are also discussed from the standpoint of quantitative and qualitative measurements. Finally, future research directions towards further advancements in the field are considered. PMID:21691441

  4. Graphene nanomesh as highly sensitive chemiresistor gas sensor

    Science.gov (United States)

    Paul, Rajat Kanti; Badhulika, Sushmee; Saucedo, Nuvia M.; Mulchandani, Ashok

    2016-01-01

    Graphene is a one atom thick carbon allotrope with all surface atoms that has attracted significant attention as a promising material as the conduction channel of a field-effect transistor and chemical field-effect transistor sensors. However, the zero bandgap of semimetal graphene still limits its application for these devices. In this work, ethanol-chemical vapor deposition (CVD) grown p-type semiconducting large-area monolayer graphene film was patterned into nanomesh by the combination of nanosphere lithography and reactive ion etching and evaluated as field-effect transistor and chemiresistor gas sensors. The resulting neck-width of the synthesized nanomesh was about ~20 nm comprised of the gap between polystyrene spheres that was formed during the reactive ion etching process. The neck-width and the periodicities of the graphene nanomesh could be easily controlled depending the duration/power of RIE and the size of PS nanospheres. The fabricated GNM transistor device exhibited promising electronic properties featuring high drive current and ION/IOFF ratio of about 6, significantly higher than its film counterpart. Similarly, when applied as chemiresistor gas sensor at room temperature, the graphene nanomesh sensor showed excellent sensitivity towards NO2 and NH3, significantly higher than their film counterparts. The ethanol-based graphene nanomesh sensors exhibited sensitivities of about 4.32%/ppm in NO2 and 0.71%/ppm in NH3 with limit of detections of 15 ppb and 160 ppb, respectively. Our demonstrated studies on controlling the neck width of the nanomesh would lead to further improvement of graphene-based transistors and sensors. PMID:22931286

  5. Innovative nanostructures for highly sensitive vibrational biosensing (Conference Presentation)

    Science.gov (United States)

    Popp, Juergen; Mayerhöfer, Thomas; Cialla-May, Dana; Weber, Karina; Huebner, Uwe

    2016-03-01

    Employing vibrational spectroscopy (IR-absorption and Raman spectroscopy) allows for the labelfree detection of molecular specific fingerprints of inorganic, organic and biological substances. The sensitivity of vibrational spectroscopy can be improved by several orders of magnitude via the application of plasmonic active surfaces. Within this contribution we will discuss two such approaches, namely surface enhanced Raman spectroscopy (SERS) as well as surface enhanced IR absorption (SEIRA). It will be shown that SERS using metal colloids as SERS active substrate in combination with a microfluidic lab-on-a-chip (LOC) device enables high throughput and reproducible measurements with highest sensitivity and specificity. The application of such a LOC-SERS approach for therapeutic drug monitoring (e.g. quantitative detection of antibiotics in a urine matrix) will be presented. Furthermore, we will introduce innovative bottom-up strategies to prepare SERS-active nanostructures coated with a lipophilic sensor layer as one-time use SERS substrates for specific food analysis (e.g. quantitative detection of toxic food colorants). The second part of this contribution presents a slit array metamaterial perfect absorber for IR sensing applications consisting of a dielectric layer sandwiched between two metallic layers of which the upper layer is perforated with a periodic array of slits. Light-matter interaction is greatly amplified in the slits, where also the analyte is concentrated, as the surface of the substrate is covered by a thin silica layer. Thus, already small concentrations of analytes down to a monolayer can be detected by refractive index sensing and identified by their spectral fingerprints with a standard mid-infrared lab spectrometer.

  6. Incremental value of magnetic resonance imaging for clinically high risk prostate cancer in 922 radical prostatectomies.

    Science.gov (United States)

    Jeong, In Gab; Lim, Ju Hyun; You, Dalsan; Kim, Mi-Hyun; Choi, Hyuk Jae; Kim, Jeong Kon; Cho, Kyoung-Sik; Hong, Jun Hyuk; Ahn, Hanjong; Kim, Choung-Soo

    2013-12-01

    We investigated the incremental value of magnetic resonance imaging in addition to clinical variables for predicting pathological outcomes and disease recurrence in patients with clinically high risk prostate cancer. A total of 922 consecutive patients with clinically high risk prostate cancer underwent magnetic resonance imaging before radical prostatectomy. We created multivariate logistic regression and Cox proportional hazards models with clinical variables only or combined with magnetic resonance imaging data to predict pathological outcomes and biochemical recurrence. The models were compared using ROC curves and the Harrell concordance index. The proportion of patients with pathological extracapsular extension, seminal vesicle invasion and lymph node metastasis was 57.5%, 12.7% and 6.3%, respectively. The sensitivity and specificity of extracapsular extension, seminal vesicle invasion and lymph node metastasis detection were 43% and 84.2%, 34.9% and 93.8%, and 14.0% and 96.9%, respectively. The area under the ROC curve of the model with clinical variable and magnetic resonance imaging data was greater than that of the model with clinical variables alone to predict extracapsular extension and seminal vesicle invasion (0.734 vs 0.697, p=0.001 and 0.750 vs 0.698, pmodel with clinical variables only and with clinical variables plus magnetic resonance imaging data was 0.563 and 0.599, respectively (p=0.003). Magnetic resonance imaging findings have incremental value in addition to clinical variables for predicting pathological outcomes and disease recurrence. Copyright © 2013 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  7. Progress with High-Field Superconducting Magnets for High-Energy Colliders

    Science.gov (United States)

    Apollinari, Giorgio; Prestemon, Soren; Zlobin, Alexander V.

    2015-10-01

    One of the possible next steps for high-energy physics research relies on a high-energy hadron or muon collider. The energy of a circular collider is limited by the strength of bending dipoles, and its maximum luminosity is determined by the strength of final focus quadrupoles. For this reason, the high-energy physics and accelerator communities have shown much interest in higher-field and higher-gradient superconducting accelerator magnets. The maximum field of NbTi magnets used in all present high-energy machines, including the LHC, is limited to ˜10 T at 1.9 K. Fields above 10 T became possible with the use of Nb3Sn superconductors. Nb3Sn accelerator magnets can provide operating fields up to ˜15 T and can significantly increase the coil temperature margin. Accelerator magnets with operating fields above 15 T require high-temperature superconductors. This review discusses the status and main results of Nb3Sn accelerator magnet research and development and work toward 20-T magnets.

  8. Facile Synthesis of Core-shell Magnetic Mesoporous Silica Nanoparticles for pH-sensitive Anticancer Drug Delivery.

    Science.gov (United States)

    Shao, Dan; Wang, Zheng; Dong, Wen-fei; Zhang, Xin; Zheng, Xiao; Xiao, Xuan-ang; Wang, Ying-shuai; Zhao, Xue; Zhang, Ming; Li, Jing; Huo, Qi-sheng; Chen, Li

    2015-12-01

    The facile synthesis of core-shell magnetic mesoporous silica nanoparticles (Fe3 O4 @mSiO2 NPs) was reported in aqueous phase using cetyltrimethylammonium bromide as a template under alcohol-free conditions. Compared to the conventional synthesis method for core-shell Fe3 O4 @mSiO2 NPs, the approach in this study is rapid (only 5-min reaction time), cheap (without using organic agents), and environmentally friendly (one-step synthesis in alcohol-free medium). Doxorubicin (DOX)-loaded Fe3 O4 @mSiO2 NPs exert extraordinarily high specificity for liver cancer cells, which was due to the pH-sensitive doxorubicin release, as well as higher endocytosis capacity in liver cancer cells rather than normal liver cells. The potential advantages of using such Fe3 O4 @mSiO2 NPs as the vehicle of anticancer drugs were that the Fe3 O4 @mSiO2 NPs exhibit good biocompatibility, high loading and protection of the guest molecules, selective killing effect, and efficient cellular uptake. The exciting pH-dependent release properties of doxorubicin-loaded Fe3 O4 @mSiO2 NPs make their use a promising strategy for enhancing efficient therapy toward tumors, while reducing the cytotoxicity of doxorubicin to human normal neutral tissue or cells. © 2015 John Wiley & Sons A/S.

  9. A Micro Saddle Coil with Switchable Sensitivity for Local High-Resolution Imaging of Luminal Tissue

    Directory of Open Access Journals (Sweden)

    Tetsuji Dohi

    2016-04-01

    Full Text Available This paper reports on a micro saddle coil for local high-resolution magnetic resonance imaging (MRI fabricated by embedding a flexible coil pattern into a polydimethyilsiloxane (PDMS tube. We can change the sensitivity of the micro coil by deforming the shape of the coil from a saddle-shaped mode to a planar-shaped mode. The inductance, the resistance, and the Q-factor of the coil in the saddle-shaped mode were 2.45 μH, 3.31 Ω, and 39.9, respectively. Those of the planar-shaped mode were 3.07 μH, 3.92 Ω, and 42.9, respectively. In MRI acquired in saddle-shaped mode, a large visible area existed around the coil. Although the sensitive area was considerably reduced in the planar-shaped mode, clear MRI images were obtained. The signal-to-noise ratios (SNR of the saddle-shaped and planar-shaped modes were 194.9 and 505.9, respectively, at voxel size of 2.0 × 2.0 × 2.0 mm3 and 11.7 and 37.4, respectively, at voxel size of 0.5 × 0.5 × 1.0 mm3. The sensitivity of the saddle-shaped and the planar-shaped modes were about 3 times and 10 times higher, respectively, than those of the medical head coil at both voxel sizes. Thus, the micro saddle coil enabled large-area imaging and highly sensitive imaging by switching the shape of the coil.

  10. A novel biosensor based on competitive SERS immunoassay and magnetic separation for accurate and sensitive detection of chloramphenicol.

    Science.gov (United States)

    Yang, Kang; Hu, Yongjun; Dong, Ning

    2016-06-15

    The accurate and sensitive detection of chloramphenicol (CAP) is particularly imperative to public health and safety. Here, we present a novel sensor for residual CAP detection based on competitive surface-enhanced Raman scattering (SERS) immunoassay and magnetic separation. In this nanosensor, functionalized Au nanoparticles (AuNPs) were labeled with the Raman reporter molecule (e.g. 4,4'-dipyridyl). With the addition of free CAP, a competitive immune reaction was initiated between free CAP and above AuNPs for conjugating with CAP antibody-modified magnetic nanoparticles (MNPs). Instead of the solid substrate, the antibody conjugated-magnetic beads were used as supporting materials and separation tools in the present sensor. With the aid of a magnet, the mixture was removed from the supernatant for concentration effects. This caused obvious change of SERS signal intensity obtained from supernatant. The SERS signals were collected from the supernatant directly, which made the SERS measurements more stable, repeatable and reliable. The proposed SERS-based magnetic immunosensor allows us to detect CAP in a fast, selective and sensitive (1.0 pg/mL) manner over a wide concentration range ( 1-1 × 10(4)pg/mL). In addition, these results demonstrate that this immunosensor holds great potential for the detection of antibiotics in real aquatic environment, which is crucial to our life. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. The role of high-field magnetic resonance imaging in parkinsonian disorders

    DEFF Research Database (Denmark)

    Lehericy, Stéphane; Vaillancourt, David E.; Seppi, Klaus

    2017-01-01

    Historically, magnetic resonance imaging (MRI) has contributed little to the study of Parkinson's disease (PD), but modern MRI approaches have unveiled several complementary markers that are useful for research and clinical applications. Iron- and neuromelanin-sensitive MRI detect qualitative...... changes in the substantia nigra. Quantitative MRI markers can be derived from diffusion weighted and iron-sensitive imaging or volumetry. Functional brain alterations at rest or during task performance have been captured with functional and arterial spin labeling perfusion MRI. These markers are useful...... understand neurodegeneration and provide reliable markers for therapeutic trials. This article reviews recent advances in MRI biomarker research at high-field (3T) and ultra high field-imaging (7T) in PD and atypical parkinsonism....

  12. High sensitivity far infrared laser diagnostics for the C-2U advanced beam-driven field-reversed configuration plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Deng, B. H., E-mail: bdeng@trialphaenergy.com; Beall, M.; Schroeder, J.; Settles, G.; Feng, P.; Kinley, J. S.; Gota, H.; Thompson, M. C. [Tri Alpha Energy, Inc., P.O. Box 7010, Rancho Santa Margarita, California 92688 (United States)

    2016-11-15

    A high sensitivity multi-channel far infrared laser diagnostics with switchable interferometry and polarimetry operation modes for the advanced neutral beam-driven C-2U field-reversed configuration (FRC) plasmas is described. The interferometer achieved superior resolution of 1 × 10{sup 16} m{sup −2} at >1.5 MHz bandwidth, illustrated by measurement of small amplitude high frequency fluctuations. The polarimetry achieved 0.04° instrument resolution and 0.1° actual resolution in the challenging high density gradient environment with >0.5 MHz bandwidth, making it suitable for weak internal magnetic field measurements in the C-2U plasmas, where the maximum Faraday rotation angle is less than 1°. The polarimetry resolution data is analyzed, and high resolution Faraday rotation data in C-2U is presented together with direct evidences of field reversal in FRC magnetic structure obtained for the first time by a non-perturbative method.

  13. High sensitivity far infrared laser diagnostics for the C-2U advanced beam-driven field-reversed configuration plasmas.

    Science.gov (United States)

    Deng, B H; Beall, M; Schroeder, J; Settles, G; Feng, P; Kinley, J S; Gota, H; Thompson, M C

    2016-11-01

    A high sensitivity multi-channel far infrared laser diagnostics with switchable interferometry and polarimetry operation modes for the advanced neutral beam-driven C-2U field-reversed configuration (FRC) plasmas is described. The interferometer achieved superior resolution of 1 × 1016 m-2 at >1.5 MHz bandwidth, illustrated by measurement of small amplitude high frequency fluctuations. The polarimetry achieved 0.04° instrument resolution and 0.1° actual resolution in the challenging high density gradient environment with >0.5 MHz bandwidth, making it suitable for weak internal magnetic field measurements in the C-2U plasmas, where the maximum Faraday rotation angle is less than 1°. The polarimetry resolution data is analyzed, and high resolution Faraday rotation data in C-2U is presented together with direct evidences of field reversal in FRC magnetic structure obtained for the first time by a non-perturbative method.

  14. Real-time brain activity measurement and signal processing system using highly sensitive MI sensor

    Directory of Open Access Journals (Sweden)

    Kewang Wang

    2017-05-01

    Full Text Available Superconducting Quantum Interference Devices (SQUIDs are the most used sensor to detect the extremely weak magnetic field of brain. However, the sensor heads need to be kept at very low temperature to maintain superconductivity, and that makes the devices large-scale and inconvenient. In order to measure brain activity in normal environment, we had constructed a measurement system based on highly sensitive Magneto-Impedance (MI sensor, and reported the study of measuring Auditory Evoked Field (AEF brain waves. In this study, the system was improved, and the sensor signals can be processed in real-time to monitor brain activity. We use this system to measure the alpha rhythm in the occipital region and the Event-Related Field (ERF P300 in the frontal, the parietal and both the temporal regions.

  15. Real-time brain activity measurement and signal processing system using highly sensitive MI sensor

    Science.gov (United States)

    Wang, Kewang; Cai, Changmei; Yamamoto, Michiharu; Uchiyama, Tsuyoshi

    2017-05-01

    Superconducting Quantum Interference Devices (SQUIDs) are the most used sensor to detect the extremely weak magnetic field of brain. However, the sensor heads need to be kept at very low temperature to maintain superconductivity, and that makes the devices large-scale and inconvenient. In order to measure brain activity in normal environment, we had constructed a measurement system based on highly sensitive Magneto-Impedance (MI) sensor, and reported the study of measuring Auditory Evoked Field (AEF) brain waves. In this study, the system was improved, and the sensor signals can be processed in real-time to monitor brain activity. We use this system to measure the alpha rhythm in the occipital region and the Event-Related Field (ERF) P300 in the frontal, the parietal and both the temporal regions.

  16. Effects of menopause and high-intensity training on insulin sensitivity and muscle metabolism

    DEFF Research Database (Denmark)

    Mandrup, Camilla M; Egelund, Jon; Nyberg, Michael

    2018-01-01

    To investigate peripheral insulin sensitivity and skeletal muscle glucose metabolism in premenopausal and postmenopausal women, and evaluate whether exercise training benefits are maintained after menopause. Sedentary, healthy, normal-weight, late premenopausal (n = 21), and early postmenopausal (n...... = 20) women were included in a 3-month high-intensity exercise training intervention. Body composition was assessed by magnetic resonance imaging and dual-energy x-ray absorptiometry, whole body glucose disposal rate (GDR) by hyperinsulinemic euglycemic clamp (40 mU/m/min), and femoral muscle glucose....... Training increased lean body mass (estimate [95% confidence interval] 0.5 [0.2-0.9] kg, P ...

  17. Acceleration sensitivity compensation in high performance crystal oscillators

    Science.gov (United States)

    Emmons, D. A.

    1978-01-01

    Two approaches to achieving reduced acceleration sensitivity of crystal oscillators are discussed. The first involves electronic compensation within the frequency control loop. The second utilizes two resonators of comparable acceleration sensitivity to compensate each other. Problems encountered in matching and tuning the resonators are discussed, as well as orientation symmetry of the frequency deviation patterns. Results on frequency stability which reflect an improved static sensitivity are presented.

  18. Highly sensitive and multiplexed platforms for allergy diagnostics

    Science.gov (United States)

    Monroe, Margo R.

    Allergy is a disorder of the immune system caused by an immune response to otherwise harmless environmental allergens. Currently 20% of the US population is allergic and 90% of pediatric patients and 60% of adult patients with asthma have allergies. These percentages have increased by 18.5% in the past decade, with predicted similar trends for the future. Here we design sensitive, multiplexed platforms to detect allergen-specific IgE using the Interferometric Reflectance Imaging Sensor (IRIS) for various clinical settings. A microarray platform for allergy diagnosis allows for testing of specific IgE sensitivity to a multitude of allergens, while requiring only small volumes of patient blood sample. However, conventional fluorescent microarray technology is limited by i) the variation of probe immobilization, which hinders the ability to make quantitative, assertive, and statistically relevant conclusions necessary in immunodiagnostics and ii) the use of fluorophore labels, which is not suitable for some clinical applications due to the tendency of fluorophores to stick to blood particulates and require daily calibration methods. This calibrated fluorescence enhancement (CaFE) method integrates the low magnification modality of IRIS with enhanced fluorescence sensing in order to directly correlate immobilized probe (major allergens) density to allergen-specific IgE in patient serum. However, this platform only operates in processed serum samples, which is not ideal for point of care testing. Thus, a high magnification modality of IRIS was adapted as an alternative allergy diagnostic platform to automatically discriminate and size single nanoparticles bound to specific IgE in unprocessed, characterized human blood and serum samples. These features make IRIS an ideal candidate for clinical and diagnostic applications, such a POC testing. The high magnification (nanoparticle counting) modality in conjunction with low magnification of IRIS in a combined instrument

  19. One-thousand-fold enhancement of high field liquid nuclear magnetic resonance signals at room temperature

    Science.gov (United States)

    Liu, Guoquan; Levien, Marcel; Karschin, Niels; Parigi, Giacomo; Luchinat, Claudio; Bennati, Marina

    2017-07-01

    Nuclear magnetic resonance (NMR) is a fundamental spectroscopic technique for the study of biological systems and materials, molecular imaging and the analysis of small molecules. It detects interactions at very low energies and is thus non-invasive and applicable to a variety of targets, including animals and humans. However, one of its most severe limitations is its low sensitivity, which stems from the small interaction energies involved. Here, we report that dynamic nuclear polarization in liquid solution and at room temperature can enhance the NMR signal of 13C nuclei by up to three orders of magnitude at magnetic fields of ∼3 T. The experiment can be repeated within seconds for signal averaging, without interfering with the sample magnetic homogeneity. The method is therefore compatible with the conditions required for high-resolution NMR. Enhancement of 13C signals on various organic compounds opens up new perspectives for dynamic nuclear polarization as a general tool to increase the sensitivity of liquid NMR.

  20. High-performance battery electrodes via magnetic templating

    Science.gov (United States)

    Sander, J. S.; Erb, R. M.; Li, L.; Gurijala, A.; Chiang, Y.-M.

    2016-08-01

    In lithium-ion batteries, the critical need for high-energy-density, low-cost storage for applications ranging from wearable computing to megawatt-scale stationary storage has created an unmet need for facile methods to produce high-density, low-tortuosity, kinetically accessible storage electrodes. Here we show that magnetic control of sacrificial features enables the creation of directional pore arrays in lithium-ion electrodes. The directional pores result in faster charge transport kinetics and enable electrodes with more than threefold higher area capacity (for example, >12 mAh cm-2 versus electric vehicle model drive cycle.

  1. Entanglement and magnetism in high-spin graphene nanodisks

    Science.gov (United States)

    Hagymási, I.; Legeza, Ö.

    2018-01-01

    We investigate the ground-state properties of triangular graphene nanoflakes with zigzag edge configurations. The description of zero-dimensional nanostructures requires accurate many-body techniques since the widely used density-functional theory with local density approximation or Hartree-Fock methods cannot handle the strong quantum fluctuations. Applying the unbiased density-matrix renormalization group algorithm we calculate the magnetization and entanglement patterns with high accuracy for different interaction strengths and compare them to the mean-field results. With the help of quantum information analysis and subsystem density matrices we reveal that the edges are strongly entangled with each other. We also address the effect of electron and hole doping and demonstrate that the magnetic properties of triangular nanoflakes can be controlled by an electric field, which reveals features of flat-band ferromagnetism. This may open up new avenues in graphene based spintronics.

  2. High-Resolution and Frequency, Printed Miniature Magnetic Probes

    Science.gov (United States)

    Prager, James; Ziemba, Timothy; Miller, Kenneth; Picard, Julian

    2013-10-01

    Eagle Harbor Technologies, Inc. (EHT) is developing a technique to significantly reduce the cost and development time of producing magnetic field diagnostics. EHT is designing probes that can be printed on flexible PCBs thereby allowing for extremely small coils to be produced while essentially eliminating the time to wind the coils. The coil size can be extremely small when coupled with the EHT Hybrid Integrator, which is capable of high bandwidth measurements over short and long pulse durations. This integrator is currently being commercialized with the support of a DOE SBIR. Additionally, the flexible PCBs allow probes to be attached to complex surface and/or probes that have a complex 3D structure to be designed and fabricated. During the Phase I, EHT will design and construct magnetic field probes on flexible PCBs, which will be tested at the University of Washington's HIT-SI experiment and in EHT's material science plasma reactor. Funding provided by DOE SBIR/STTR Program.

  3. Development of Hf(4+)-immobilized polydopamine-coated magnetic graphene for highly selective enrichment of phosphopeptides.

    Science.gov (United States)

    Lin, Haizhu; Deng, Chunhui

    2016-01-01

    In this work, we first designed and synthesized an IMAC material with Hf(4+) immobilized on polydopamine-coated magnetic graphene and applied it to phosphopeptides enrichment successfully. The newly prepared material gathered the advantages of large specific surface area of graphene, good hydrophilicity and biocompatibility of polydopamine and superparamagnetism of Fe3O4. We investigated the performance of Hf(4+)-immobilized polydopamine-coated magnetic graphene (denoted as magG@PDA-Hf(4+)) in phosphopeptides enrichment and the results showed high selectivity and sensitivity of the new material. Finally, we successfully applied magG@PDA-Hf(4+) to phosphopeptides enrichment from non-fat milk digests and human serum, further demonstrating excellent performance of this new material in phosphopeptides enrichment. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Adjoint sensitivity analysis of high frequency structures with Matlab

    CERN Document Server

    Bakr, Mohamed; Demir, Veysel

    2017-01-01

    This book covers the theory of adjoint sensitivity analysis and uses the popular FDTD (finite-difference time-domain) method to show how wideband sensitivities can be efficiently estimated for different types of materials and structures. It includes a variety of MATLAB® examples to help readers absorb the content more easily.

  5. Characterization of three high efficiency and blue sensitive silicon photomultipliers

    Science.gov (United States)

    Otte, Adam Nepomuk; Garcia, Distefano; Nguyen, Thanh; Purushotham, Dhruv

    2017-02-01

    We report about the optical and electrical characterization of three high efficiency and blue sensitive Silicon photomultipliers from FBK, Hamamatsu, and SensL. Key features of the tested devices when operated at 90% breakdown probability are peak photon detection efficiencies between 40% and 55%, temperature dependencies of gain and PDE that are less than 1%/°C, dark rates of ∼50 kHz/mm2 at room temperature, afterpulsing of about 2%, and direct optical crosstalk between 6% and 20%. The characteristics of all three devices impressively demonstrate how the Silicon-photomultiplier technology has improved over the past ten years. It is further demonstrated how the voltage and temperature characteristics of a number of quantities can be parameterized on the basis of physical models. The models provide a deeper understanding of the device characteristics over a wide bias and temperature range. They also serve as examples how producers could provide the characteristics of their SiPMs to users. A standardized parameterization of SiPMs would enable users to find the optimal SiPM for their application and the operating point of SiPMs without having to perform measurements thus significantly reducing design and development cycles.

  6. Improvement of sensitivity in high-resolution Rutherford backscattering spectroscopy.

    Science.gov (United States)

    Hashimoto, H; Nakajima, K; Suzuki, M; Sasakawa, K; Kimura, K

    2011-06-01

    The sensitivity (limit of detection) of high-resolution Rutherford backscattering spectroscopy (HRBS) is mainly determined by the background noise of the spectrometer. There are two major origins of the background noise in HRBS, one is the stray ions scattered from the inner wall of the vacuum chamber of the spectrometer and the other is the dark noise of the microchannel plate (MCP) detector which is commonly used as a focal plane detector of the spectrometer in HRBS. In order to reject the stray ions, several barriers are installed inside the spectrometer and a thin Mylar foil is mounted in front of the detector. The dark noise of the MCP detector is rejected by the coincidence measurement with the secondary electrons emitted from the Mylar foil upon the ion passage. After these improvements, the background noise is reduced by a factor of 200 at a maximum. The detection limit can be improved down to 10 ppm for As in Si at a measurement time of 1 h under ideal conditions. © 2011 American Institute of Physics

  7. Ultra-high sensitivity imaging of cancer using SERRS nanoparticles

    Science.gov (United States)

    Kircher, Moritz F.

    2016-05-01

    "Surface-enhanced Raman spectroscopy" (SERS) nanoparticles have gained much attention in recent years for in silico, in vitro and in vivo sensing applications. Our group has developed novel generations of biocompatible "surfaceenhanced resonance Raman spectroscopy" (SERRS) nanoparticles as novel molecular imaging agents. Via rigorous optimization of the different variables contributing to the Raman enhancement, we were able to design SERRS nanoparticles with so far unprecedented sensitivity of detection under in vivo imaging conditions (femto-attomolar range). This has resulted in our ability to visualize, with a single nanoparticle, many different cancer types (after intravenous injection) in mouse models. The cancer types we have tested so far include brain, breast, esophagus, stomach, pancreas, colon, sarcoma, and prostate cancer. All mouse models used are state-of-the-art and closely mimic the tumor biology in their human counterparts. In these animals, we were able to visualize not only the bulk tumors, but importantly also microscopic extensions and locoregional satellite metastases, thus delineating for the first time the true extent of tumor spread. Moreover, the particles enable the detection of premalignant lesions. Given their inert composition they are expected to have a high chance for clinical translation, where we envision them to have an impact in various scenarios ranging from early detection, image-guidance in open or minimally invasive surgical procedures, to noninvasive imaging in conjunction with spatially offset (SESORS) Raman detection devices.

  8. CMOS capacitive biosensors for highly sensitive biosensing applications.

    Science.gov (United States)

    Chang, An-Yu; Lu, Michael S-C

    2013-01-01

    Magnetic microbeads are widely used in biotechnology and biomedical research for manipulation and detection of cells and biomolecules. Most lab-on-chip systems capable of performing manipulation and detection require external instruments to perform one of the functions, leading to increased size and cost. This work aims at developing an integrated platform to perform these two functions by implementing electromagnetic microcoils and capacitive biosensors on a CMOS (complementary metal oxide semiconductor) chip. Compared to most magnetic-type sensors, our detection method requires no externally applied magnetic fields and the associated fabrication is less complicated. In our experiment, microbeads coated with streptavidin were driven to the sensors located in the center of microcoils with functionalized anti-streptavidin antibody. Detection of a single microbead was successfully demonstrated using a capacitance-to-frequency readout. The average capacitance changes for the experimental and control groups were -5.3 fF and -0.2 fF, respectively.

  9. Symmetry-Breaking as a Paradigm to Design Highly-Sensitive Sensor Systems

    Directory of Open Access Journals (Sweden)

    Antonio Palacios

    2015-06-01

    Full Text Available A large class of dynamic sensors have nonlinear input-output characteristics, often corresponding to a bistable potential energy function that controls the evolution of the sensor dynamics. These sensors include magnetic field sensors, e.g., the simple fluxgate magnetometer and the superconducting quantum interference device (SQUID, ferroelectric sensors and mechanical sensors, e.g., acoustic transducers, made with piezoelectric materials. Recently, the possibilities offered by new technologies and materials in realizing miniaturized devices with improved performance have led to renewed interest in a new generation of inexpensive, compact and low-power fluxgate magnetometers and electric-field sensors. In this article, we review the analysis of an alternative approach: a symmetry-based design for highly-sensitive sensor systems. The design incorporates a network architecture that produces collective oscillations induced by the coupling topology, i.e., which sensors are coupled to each other. Under certain symmetry groups, the oscillations in the network emerge via an infinite-period bifurcation, so that at birth, they exhibit a very large period of oscillation. This characteristic renders the oscillatory wave highly sensitive to symmetry-breaking effects, thus leading to a new detection mechanism. Model equations and bifurcation analysis are discussed in great detail. Results from experimental works on networks of fluxgate magnetometers are also included.

  10. Highly sensitive NIR PtSi/Si-nanostructure detectors

    Science.gov (United States)

    Li, Hua-gao; Guo, Pei; Yuan, An-bo; Long, Fei; Li, Rui-zhi; Li, Ping; Li, Yi

    2016-10-01

    We report a high external quantum efficiency (EQE) photodiode detector with PtSi/Si-nanostructures. Black silicon nanostructures were fabricated by metal-assist chemical etching (MCE), a 2 nm Pt layer was subsequently deposited on black silicon surface by DC magnetron sputtering system, and PtSi/Si-nanostructures were formed in vacuum annealing at 450 oC for 5 min. As the PtSi/Si-nanostructures presented a spiky shape, the absorption of incident light was remarkably enhanced for the repeat reflection and absorption. The breakdown voltage, dark current, threshold voltage and responsivity of the device were investigated to evaluate the performance of the PtSi/Si-nanostructures detector. The threshold voltage and dark currents of the PtSi/Si-nanostructure photodiode tends to be slightly higher than those of the standard diodes. The breakdown voltage remarkably was reduced because of existing avalanche breakdown in PtSi/Si-nanostructures. However, the photodiodes had high response at room temperature in near infrared region. At -5 V reverse bias voltage, the responsivity was 0.72 A/W in 1064 nm wavelength, and the EQE was 83.9%. By increasing the reverse bias voltage, the responsivity increased. At -60 V reverse bias voltage, the responsivity was 3.5 A/W, and the EQE was 407.5%, which means the quantum efficiency of PtSi/Si-nanostructure photodiodes was about 10 times higher than that of a standard diode. Future research includes how to apply this technology to enhance the NIR sensitivity of image sensors, such as Charge Coupled Devices (CCD).

  11. Orientation and thickness dependence of magnetization at the interfacesof highly spin-polarized manganite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chopdekar, Rajesh V.; Arenholz, Elke; Suzuki, Y.

    2008-08-18

    We have probed the nature of magnetism at the surface of (001), (110) and (111)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films. The spin polarization of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films is not intrinsically suppressed at all surfaces and interfaces but is highly sensitive to both the epitaxial strain state as well as the substrate orientation. Through the use of soft x-ray spectroscopy, the magnetic properties of (001), (110) and (111)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/SrTiO{sub 3} interfaces have been investigated and compared to bulk magnetometry and resistivity measurements. The magnetization of (110) and (111)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/SrTiO{sub 3} interfaces are more bulk-like as a function of thickness whereas the magnetization at the (001)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/SrTiO{sub 3} interface is suppressed significantly below a layer thickness of 20 nm. Such findings are correlated with the biaxial strain state of the La{sub 0.7}Sr{sub 0.3}MnO{sub 3} films; for a given film thickness it is the tetragonal distortion of (001) La{sub 0.7}Sr{sub 0.3}MnO{sub 3} that severely impacts the magnetization, whereas the trigonal distortion for (111)-oriented films and monoclinic distortion for (110)-oriented films have less of an impact. These observations provide evidence that surface magnetization and thus spin polarization depends strongly on the crystal surface orientation as well as epitaxial strain.

  12. Probing Primordial Magnetic Fields with 21-cm Line Observations of the High-redshift Intergalactic Medium

    Science.gov (United States)

    Oklopcic, Antonija; Gluscevic, V.; Hirata, C. M.; Mishra, A.; Venumadhav, T. N.

    2014-01-01

    Coherent magnetic fields with strengths of the order of 10^(-5) G are observed on scales of individual galaxies, including the Milky Way. They are thought to be organized and maintained by a dynamo mechanism. However, the nature and origin of the seed magnetic field, required for the dynamo effect to take place, are still unknown. Here, we propose a method of probing the magnetic field in the intergalactic medium before the Epoch of Reionization through observations of redshifted 21-cm radiation of neutral hydrogen. The 21-cm line is created during the spin-flip transition between the hyperfine levels of the hydrogen ground state. The upper hyperfine level is a triplet consisting of atomic states with three different projections of the total angular momentum vector. Anisotropic 21-cm radiation, resulting from perturbations in the high-redshift IGM, unevenly populates triplet sublevels. If an atom is located in an external magnetic field, it precesses between the three states; this causes an additional anisotropy in the 21-cm radiation, which could be imprinted in the 21-cm power spectrum. In order to evaluate the effect of the magnetic field, we need to consider in full detail all mechanisms that affect the distribution of atoms in hyperfine sublevels, such as the interaction of hydrogen atoms with the 21-cm radiation, optical pumping by Lyman-alpha photons, and spin-exchange in hydrogen-hydrogen collisions. Preliminary calculations suggest that this method could be sensitive to extremely weak magnetic fields, of the order of 10^(-17) G.

  13. High throughput modular chambers for rapid evaluation of anesthetic sensitivity

    Directory of Open Access Journals (Sweden)

    Eckmann David M

    2006-11-01

    Full Text Available Abstract Background Anesthetic sensitivity is determined by the interaction of multiple genes. Hence, a dissection of genetic contributors would be aided by precise and high throughput behavioral screens. Traditionally, anesthetic phenotyping has addressed only induction of anesthesia, evaluated with dose-response curves, while ignoring potentially important data on emergence from anesthesia. Methods We designed and built a controlled environment apparatus to permit rapid phenotyping of twenty-four mice simultaneously. We used the loss of righting reflex to indicate anesthetic-induced unconsciousness. After fitting the data to a sigmoidal dose-response curve with variable slope, we calculated the MACLORR (EC50, the Hill coefficient, and the 95% confidence intervals bracketing these values. Upon termination of the anesthetic, Emergence timeRR was determined and expressed as the mean ± standard error for each inhaled anesthetic. Results In agreement with several previously published reports we find that the MACLORR of halothane, isoflurane, and sevoflurane in 8–12 week old C57BL/6J mice is 0.79% (95% confidence interval = 0.78 – 0.79%, 0.91% (95% confidence interval = 0.90 – 0.93%, and 1.96% (95% confidence interval = 1.94 – 1.97%, respectively. Hill coefficients for halothane, isoflurane, and sevoflurane are 24.7 (95% confidence interval = 19.8 – 29.7%, 19.2 (95% confidence interval = 14.0 – 24.3%, and 33.1 (95% confidence interval = 27.3 – 38.8%, respectively. After roughly 2.5 MACLORR • hr exposures, mice take 16.00 ± 1.07, 6.19 ± 0.32, and 2.15 ± 0.12 minutes to emerge from halothane, isoflurane, and sevoflurane, respectively. Conclusion This system enabled assessment of inhaled anesthetic responsiveness with a higher precision than that previously reported. It is broadly adaptable for delivering an inhaled therapeutic (or toxin to a population while monitoring its vital signs, motor reflexes, and providing precise control

  14. Pulsed magnetic field excitation sensitivity of match-type electric blasting caps

    Science.gov (United States)

    Parson, Jonathan; Dickens, James; Walter, John; Neuber, Andreas A.

    2010-10-01

    This paper presents a study on energy deposition and electromagnetic compatibility of match-type electroexplosive devices (EEDs), which recently have found more usage in pulsed power environments with high electromagnetic interference (EMI) background. The sensitivity of these devices makes them dangerous to intended and unintended radiation produced by devices commonly used in pulsed power environments. Match-type EEDs have been found to be susceptible to such low levels of energy (7-8 mJ) that safe operation of these EEDs is vital when in use near devices that produce high levels of pulsed EMI. The scope of this paper is to provide an investigation that incorporates results of similar studies to provide detonation characteristics of these EEDs. The three topics included in this study are sensitivity testing, modeling of the thermodynamic heat propagation, and electromagnetic compatibility from pulsed electromagnetic radiation. The thermodynamic joule heating of the primary explosive has been modeled by a solution to the 1D heat equation. A simple pulsed generator, Marx generator with an inductive load, was used for the electromagnetic compatibility assessment of the coupled field between the pulse generator and shorted EED. The results of the electromagnetic compatibility assessment relate the resistive, inductive, and capacitive components of the pulse generator to the area of the shorted EED.

  15. Pulsed magnetic field excitation sensitivity of match-type electric blasting caps.

    Science.gov (United States)

    Parson, Jonathan; Dickens, James; Walter, John; Neuber, Andreas A

    2010-10-01

    This paper presents a study on energy deposition and electromagnetic compatibility of match-type electroexplosive devices (EEDs), which recently have found more usage in pulsed power environments with high electromagnetic interference (EMI) background. The sensitivity of these devices makes them dangerous to intended and unintended radiation produced by devices commonly used in pulsed power environments. Match-type EEDs have been found to be susceptible to such low levels of energy (7-8 mJ) that safe operation of these EEDs is vital when in use near devices that produce high levels of pulsed EMI. The scope of this paper is to provide an investigation that incorporates results of similar studies to provide detonation characteristics of these EEDs. The three topics included in this study are sensitivity testing, modeling of the thermodynamic heat propagation, and electromagnetic compatibility from pulsed electromagnetic radiation. The thermodynamic joule heating of the primary explosive has been modeled by a solution to the 1D heat equation. A simple pulsed generator, Marx generator with an inductive load, was used for the electromagnetic compatibility assessment of the coupled field between the pulse generator and shorted EED. The results of the electromagnetic compatibility assessment relate the resistive, inductive, and capacitive components of the pulse generator to the area of the shorted EED.

  16. High resolution magnetic force microscopy using focused ion beam modified tips

    NARCIS (Netherlands)

    Phillips, G.N.; Siekman, Martin Herman; Abelmann, Leon; Lodder, J.C.

    2002-01-01

    Atomic force microscope tips coated by the thermal evaporation of a magnetic 30 nm thick Co film have been modified by focused ion beam milling with Ga+ ions to produce tips suitable for magnetic force microscopy. Such tips possess a planar magnetic element with high magnetic shape anisotropy, an

  17. High-performance Bi(2)Te(3)-based topological insulator film magnetic field detector.

    Science.gov (United States)

    Zhang, H B; Li, H; Shao, J M; Li, S W; Bao, D H; Yang, G W

    2013-11-27

    Topological insulators with the nanoscaled metallic surface state (3-5 nm) are actually of typical functional nanostructures. Significant efforts have been devoted to study new families of topological insulators and identifications of topological surface state, as well as fundamental physics issues relating to spin-polarized surface electronic states in the past few years. However, transport investigations that can provide direct experimental evidence for potentially practical applications of topological insulators are limited, and realization of functional devices based on topological insulators is still under exploration. Here, using the Sn-doping Bi2Te3 polycrystalline topological insulator films, we fabricated high-performance current-controlled magnetic field detectors. When a parallel magnetic field is applied, the as-fabricated device exhibits a stable and reproducible magneto-resistance (MR) switching behavior, and the corresponding MR ratio can be modulated by the applied current. Even under such a low magnetic field (0.5 kG), the device still shows a distinguishable MR switching performance, suggesting that topological insulator devices are very sensitive to external stimulation and potentially applicable to weak magnetic field detection.

  18. Evidence for single-chain magnet behavior in a Mn(III)-Ni(II) chain designed with high spin magnetic units: a route to high temperature metastable magnets.

    Science.gov (United States)

    Clérac, Rodolphe; Miyasaka, Hitoshi; Yamashita, Masahiro; Coulon, Claude

    2002-10-30

    . This result indicates the presence of a metastable state without magnetic long-range order. This material is the first experimental design of a heterometallic chain with ST = 3 magnetic units showing a "single-chain magnet" behavior predicted in 1963 by R. J. Glauber for an Ising one-dimensional system. This work opens new perspectives for one-dimensional systems to obtain high temperature metastable magnets by combining high spin magnetic units, strong interunit interactions, and uniaxial anisotropy.

  19. Building high-coverage monolayers of covalently bound magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Mackenzie G.; Teplyakov, Andrew V., E-mail: andrewt@udel.edu

    2016-12-01

    Graphical abstract: - Highlights: • A method for forming a layer of covalently bound nanoparticles is offered. • A nearly perfect monolayer of covalently bound magnetic nanoparticles was formed on gold. • Spectroscopic techniques confirmed covalent binding by the “click” reaction. • The influence of the functionalization scheme on surface coverage was investigated. - Abstract: This work presents an approach for producing a high-coverage single monolayer of magnetic nanoparticles using “click chemistry” between complementarily functionalized nanoparticles and a flat substrate. This method highlights essential aspects of the functionalization scheme for substrate surface and nanoparticles to produce exceptionally high surface coverage without sacrificing selectivity or control over the layer produced. The deposition of one single layer of magnetic particles without agglomeration, over a large area, with a nearly 100% coverage is confirmed by electron microscopy. Spectroscopic techniques, supplemented by computational predictions, are used to interrogate the chemistry of the attachment and to confirm covalent binding, rather than attachment through self-assembly or weak van der Waals bonding. Density functional theory calculations for the surface intermediate of this copper-catalyzed process provide mechanistic insight into the effects of the functionalization scheme on surface coverage. Based on this analysis, it appears that steric limitations of the intermediate structure affect nanoparticle coverage on a flat solid substrate; however, this can be overcome by designing a functionalization scheme in such a way that the copper-based intermediate is formed on the spherical nanoparticles instead. This observation can be carried over to other approaches for creating highly controlled single- or multilayered nanostructures of a wide range of materials to result in high coverage and possibly, conformal filling.

  20. Haemocompatibility of iron oxide nanoparticles synthesized for theranostic applications: a high-sensitivity microfluidic tool

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Raquel O. [Polytechnic Institute of Bragança, Laboratory of Separation and Reaction Engineering-Laboratory of Catalysis and Materials (LSRE-LCM) (Portugal); Bañobre-López, Manuel; Gallo, Juan [INL-International Iberian Nanotechnology Laboratory, Advanced (Magnetic) Theranostic Nanostructures Lab (Portugal); Tavares, Pedro B. [Universidade de Trás-os-Montes e Alto Douro, CQVR-Centro de Química-Vila Real (Portugal); Silva, Adrián M. T. [Universidade do Porto, Laboratory of Separation and Reaction Engineering-Laboratory of Catalysis and Materials (LSRE-LCM), Faculdade de Engenharia (Portugal); Lima, Rui, E-mail: rl@dem.uminho.pt [MEtRiCS, University of Minho, Mechanical Engineering Department (Portugal); Gomes, Helder T. [Polytechnic Institute of Bragança, Laboratory of Separation and Reaction Engineering-Laboratory of Catalysis and Materials (LSRE-LCM) (Portugal)

    2016-07-15

    The poor heating efficiency of the most reported magnetic nanoparticles (MNPs), allied to the lack of comprehensive biocompatibility and haemodynamic studies, hampers the spread of multifunctional nanoparticles as the next generation of therapeutic bio-agents in medicine. The present work reports the synthesis and characterization, with special focus on biological/toxicological compatibility, of superparamagnetic nanoparticles with diameter around 18 nm, suitable for theranostic applications (i.e. simultaneous diagnosis and therapy of cancer). Envisioning more insights into the complex nanoparticle-red blood cells (RBCs) membrane interaction, the deformability of the human RBCs in contact with magnetic nanoparticles (MNPs) was assessed for the first time with a microfluidic extensional approach, and used as an indicator of haematological disorders in comparison with a conventional haematological test, i.e. the haemolysis analysis. Microfluidic results highlight the potential of this microfluidic tool over traditional haemolysis analysis, by detecting small increments in the rigidity of the blood cells, when traditional haemotoxicology analysis showed no significant alteration (haemolysis rates lower than 2 %). The detected rigidity has been predicted to be due to the wrapping of small MNPs by the bilayer membrane of the RBCs, which is directly related to MNPs size, shape and composition. The proposed microfluidic tool adds a new dimension into the field of nanomedicine, allowing to be applied as a high-sensitivity technique capable of bringing a better understanding of the biological impact of nanoparticles developed for clinical applications.

  1. Nb3Sn High Field Magnets for the High Luminosity LHC Upgrade Project

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosio, Giorgio

    2015-06-01

    The High Luminosity upgrade of the Large Hadron Collider at CERN requires a new generation of high field superconducting magnets. High field large aperture quadrupoles (MQXF) are needed for the low-beta triplets close to the ATLAS and CMS detectors, and high field two-in-one dipoles (11 T dipoles) are needed to make room for additional collimation. The MQXF quadrupoles, with a field gradient of 140 T/m in 150 mm aperture, have a peak coil field of 12.1 T at nominal current. The 11 T dipoles, with an aperture of 60 mm, have a peak coil field of 11.6 T at nominal current. Both magnets require Nb3Sn conductor and are the first applications of this superconductor to actual accelerator magnets.

  2. High-sensitivity operation of single-beam optically pumped magnetometer in a kHz frequency range

    Science.gov (United States)

    Savukov, I.; Kim, Y. J.; Shah, V.; Boshier, M. G.

    2017-03-01

    Optically pumped magnetometers (OPM) can be used in various applications, from magnetoencephalography to magnetic resonance imaging and nuclear quadrupole resonance (NQR). OPMs provide high sensitivity and have the significant advantage of non-cryogenic operation. To date, many magnetometers have been demonstrated with sensitivity close to 1 fT, but most devices are not commercialized. Most recently, QuSpin developed a model of OPM that is low cost, high sensitivity, and convenient for users, which operates in a single-beam configuration. Here we developed a theory of single-beam (or parallel two-beam) magnetometers and showed that it is possible to achieve good sensitivity beyond their usual frequency range by tuning the magnetic field. Experimentally we have tested and optimized a QuSpin OPM for operation in the frequency range from DC to 1.7 kHz, and found that the performance was only slightly inferior despite the expected decrease due to deviation from the spin-exchange relaxation-free regime.

  3. Unexpected Windy Weather Around a Highly Magnetized Neutron Star

    Science.gov (United States)

    Younes, George A.; Kouveliotou, Chryssa; Kargaltsev, Oleg; Gill, Ramandeep; Granot, Jonathan; Watts, Anna; Gelfand, Joseph; Baring, Matthew G.; Kust Harding, Alice; Pavlov, George G.; van der Horst, Alexander; Huppenkothen, Daniela; Gögüs, Ersin; Lin, Lin; Roberts, Oliver

    2016-04-01

    Magnetars and rotation-powered pulsars (RPPs) historically represented two distinct subclasses of neutron stars. Magnetars are slowly-rotating (~2-12 s), isolated neutron stars (NSs) with super-strong magnetic fields, B~10^13-10^15 G. RPPs, on the other hand, are rapidly-rotating (~0.01-0.3~s), isolated NSs with surface dipole magnetic field in the range ~10^11-10^13 G. Most pulsars possess a large rotational energy loss rate that powers a relativistic magnetized particle wind, often seen as a pulsar wind nebula (PWN; the Crab PWN being the most famous). There has not yet been convincing evidence for a wind nebula around magnetars, most likely due to their low rotational energy loss rate. Here, we report the study of new deep X-ray observations of the peculiar extended emission around the magnetar Swift J1834.9-0846. Our new results strongly support a wind nebula as the nature of the extended emission, thus, establishing Swift J1834.9-0846 as the first magnetar to possess a surrounding nebula. This implies that wind nebulae are no longer exclusive to RPPs and, along with recent discoveries in the field, further narrow the gaps between these two sub-populations of isolated NSs. The physical properties of this wind nebula, however, show peculiarities, especially its high radiative efficiency of about 10%, only shared with two other known very young RPPs, the Crab and its twin.

  4. A sensitive and selective spectrophotometric method for 2-chlorophenol based on solid phase extraction with mixed hemimicelle magnetic nanoparticles

    Directory of Open Access Journals (Sweden)

    Siriboon Mukdasai

    2016-05-01

    Full Text Available The first study of a sensitive and selective spectrophotometric detection of 2-chlorophenol (2-CP was reported. The method is based on derivatization of 2-CP with 4-aminoantipyrine (4-AAP and subsequent preconcentration by solid phase extraction (SPE using mixed hemimicelles adsorbent of cetyltrimethylammonium bromide coated magnetic nanoparticles (CTAB coated Fe3O4 NPs before its detection by spectrophotometry at 510 nm. The adsorption capacity was evaluated using the Langmuir adsorption isotherm model, with high correlation coefficients (R2 = 0.9983. The optimum conditions for SPE were CTAB coated Fe3O4 NPs 20 mg under vortex 60 s and methanol as the desorption solvent under sonication for 7 min. The linearity of the method was in the range of 0.05–1.0 mg L−1 with correlation coefficient (0.9970. The limit of detection (LOD and limit of quantitation (LOQ were 0.01 mg L−1 and 0.05 mg L−1, respectively. Good precision with relative standard deviation (%RSD, n = 5 less than 3.7% was obtained. The method was successfully applied for the determination of 2-CP in soil samples with satisfactory recoveries (81.7–95.2%.

  5. Magnetic nanocomposite sensor

    KAUST Repository

    Alfadhel, Ahmed

    2016-05-06

    A magnetic nanocomposite device is described herein for a wide range of sensing applications. The device utilizes the permanent magnetic behavior of the nanowires to allow operation without the application of an additional magnetic field to magnetize the nanowires, which simplifies miniaturization and integration into microsystems. In5 addition, the nanocomposite benefits from the high elasticity and easy patterning of the polymer-based material, leading to a corrosion-resistant, flexible material that can be used to realize extreme sensitivity. In combination with magnetic sensor elements patterned underneath the nanocomposite, the nanocomposite device realizes highly sensitive and power efficient flexible artificial cilia sensors for flow measurement or tactile sensing.

  6. High-sensitivity multifunctional spinner magnetometer using a magneto-impedance sensor

    Science.gov (United States)

    Kodama, Kazuto

    2017-01-01

    A novel spinner magnetometer was developed with a wide dynamic range from 10-10 to 10-4 Am2 and a resolution of 10-11 Am2. High sensitivity was achieved with the use of a magneto-impedance (MI) sensor, which is a compact, sensitive magnetic sensor used industrially. Its slow-spinning rate (5 Hz) and the incorporation of a unique mechanism for adjusting the spacing between the sensing unit and the spinning axis allows the measurement of fragile samples sized 10-50 mm. The sensor configuration, in which a pair of MI sensors is connected in opposite serial, along with an amplification circuit with a programmable low-pass filter, reduces the problems of external noise and sensor drift. The signal, with reference to the spinning frequency, is detected with a lock-in amplifier. The MI spinner has two selectable measurement modes: the fundamental mode (F mode) and the harmonic mode (H mode). Measurements in the F mode detect signals of the fundamental frequency (5 Hz), in the same way as conventional spinner magnetometers. In the H mode, the second (10 Hz) and the third (15 Hz) harmonic components are measured, in addition to the fundamental component. Tests in the H mode were performed using a small coil and a natural sample to simulate dipoles with various degrees of offset. The results revealed that the magnitude of the fundamental component of the offset dipole was systematically larger (by several percent) than that of the nonoffset dipole. These findings suggest that this novel MI spinner will be useful in estimating the inhomogeneity of the magnetization of a sample that can equivalently be described by an offset dipole.

  7. A Simple Approach for Obtaining High Resolution, High Sensitivity ¹H NMR Metabolite Spectra of Biofluids with Limited Mass Supply

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jian Zhi; Rommereim, Donald N.; Wind, Robert A.; Minard, Kevin R.; Sears, Jesse A.

    2006-11-01

    A simple approach is reported that yields high resolution, high sensitivity ¹H NMR spectra of biofluids with limited mass supply. This is achieved by spinning a capillary sample tube containing a biofluid at the magic angle at a frequency of about 80Hz. A 2D pulse sequence called ¹H PASS is then used to produce a high-resolution ¹H NMR spectrum that is free from magnetic susceptibility induced line broadening. With this new approach a high resolution ¹H NMR spectrum of biofluids with a volume less than 1.0 µl can be easily achieved at a magnetic field strength as low as 7.05T. Furthermore, the methodology facilitates easy sample handling, i.e., the samples can be directly collected into inexpensive and disposable capillary tubes at the site of collection and subsequently used for NMR measurements. In addition, slow magic angle spinning improves magnetic field shimming and is especially suitable for high throughput investigations. In this paper first results are shown obtained in a magnetic field of 7.05T on urine samples collected from mice using a modified commercial NMR probe.

  8. Highly sensitive and selective colorimetric sensing of antibiotics in milk.

    Science.gov (United States)

    Zhang, Xiaofang; Zhang, Yang; Zhao, Hong; He, Yujian; Li, Xiangjun; Yuan, Zhuobin

    2013-05-17

    Antibiotics residues in foods are very harmful to human beings. Determination of antibiotics residues relies largely on the availability of adequate analytical techniques. Currently, there is an urgent need for on site and real time detection of antibiotics in food. In this work, a novel one step synthesis of gold nanoparticles (AuNPs) was proposed using pyrocatechol violet (PCV) as a reducer agent. Highly sensitive and selective colorimetric detection of four antibiotics kanamycin mono sulfate (KA), neomycin sulfate (NE), streptomycin sulfate (ST) and bleomycin sulfate (BL) was realized during the formation of AuNPs. PCV has -OH groups and these antibiotics have -OH, -NH2, -NH- groups, so there may be some special hydrogen-bonding interactions between PCV and these antibiotics. Therefore, the presence of KA, NE, ST and BL would influence the synthesis of AuNPs, then the color and state of AuNPs would change, which could be observed with the naked eye or a UV-vis spectrophotometer. Results showed that A670 was linear with the logarithm of KA concentration in the range from 1.0×10(-8) to 5.0×10(-7)M and 5.0×10(-7) to 5.5×10(-5)M. The detection limit of KA was 1.0×10(-9)M (S/N=3). The coexisting substances including 1.0×10(-5)M phenylalanine, alanine, glycerol, glucose, Mg(2+), Ca(2+), Na(+), K(+), CO3(2-), SO4(2-), NO3(-), Cl(-) and Br(-) did not affect the determination of 1.0×10(-7)M antibiotics. In particular, the proposed method could be applied successfully to the detection of antibiotics in the pretreated liquid milk products. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Highly sensitive and unbiased approach for elucidating antibody repertoires.

    Science.gov (United States)

    Lin, Sherry G; Ba, Zhaoqing; Du, Zhou; Zhang, Yu; Hu, Jiazhi; Alt, Frederick W

    2016-07-12

    Developing B lymphocytes undergo V(D)J recombination to assemble germ-line V, D, and J gene segments into exons that encode the antigen-binding variable region of Ig heavy (H) and light (L) chains. IgH and IgL chains associate to form the B-cell receptor (BCR), which, upon antigen binding, activates B cells to secrete BCR as an antibody. Each of the huge number of clonally independent B cells expresses a unique set of IgH and IgL variable regions. The ability of V(D)J recombination to generate vast primary B-cell repertoires results from a combinatorial assortment of large numbers of different V, D, and J segments, coupled with diversification of the junctions between them to generate the complementary determining region 3 (CDR3) for antigen contact. Approaches to evaluate in depth the content of primary antibody repertoires and, ultimately, to study how they are further molded by secondary mutation and affinity maturation processes are of great importance to the B-cell development, vaccine, and antibody fields. We now describe an unbiased, sensitive, and readily accessible assay, referred to as high-throughput genome-wide translocation sequencing-adapted repertoire sequencing (HTGTS-Rep-seq), to quantify antibody repertoires. HTGTS-Rep-seq quantitatively identifies the vast majority of IgH and IgL V(D)J exons, including their unique CDR3 sequences, from progenitor and mature mouse B lineage cells via the use of specific J primers. HTGTS-Rep-seq also accurately quantifies DJH intermediates and V(D)J exons in either productive or nonproductive configurations. HTGTS-Rep-seq should be useful for studies of human samples, including clonal B-cell expansions, and also for following antibody affinity maturation processes.

  10. Using Bio-Functionalized Magnetic Nanoparticles and Dynamic Nuclear Magnetic Resonance to Characterize the Time-Dependent Spin-Spin Relaxation Time for Sensitive Bio-Detection

    Directory of Open Access Journals (Sweden)

    Shu-Hsien Liao

    2014-11-01

    Full Text Available In this work, we report the use of bio-functionalized magnetic nanoparticles (BMNs and dynamic magnetic resonance (DMR to characterize the time-dependent spin-spin relaxation time for sensitive bio-detection. The biomarkers are the human C-reactive protein (CRP while the BMNs are the anti-CRP bound onto dextran-coated Fe3O4 particles labeled as Fe3O4-antiCRP. It was found the time-dependent spin-spin relaxation time, T2, of protons decreases as time evolves. Additionally, the ΔT2 of of protons in BMNs increases as the concentration of CRP increases. We attribute these to the formation of the magnetic clusters that deteriorate the field homogeneity of nearby protons. A sensitivity better than 0.1 μg/mL for assaying CRP is achieved, which is much higher than that required by the clinical criteria (0.5 mg/dL. The present MR-detection platform shows promise for further use in detecting tumors, viruses, and proteins.

  11. High-Magnetic-Field and High-Pressure Effects in Monocrystalline URu2Si2

    NARCIS (Netherlands)

    Boer, F.R. de; Franse, J.J.M.; Louis, E.; Menovsky, A.A.; Mydosh, J.A.; Palstra, T.T.M.; Rauchschwalbe, U.; Schlabitz, W.; Steglich, F.; Visser, A. de

    1986-01-01

    High-field magnetisation and high-pressure resistivity measurements have been performed on monocrystalline samples of the superconducting compound URu2Si2 just above Tc. At 1.4 K, well below the magnetic ordering temperature of about 17.5K, two sharp transitions at 36 and 40 T have been observed in

  12. High-intensity xenon plasma discharge lamp for bulk-sensitive high-resolution photoemission spectroscopy.

    Science.gov (United States)

    Souma, S; Sato, T; Takahashi, T; Baltzer, P

    2007-12-01

    We have developed a highly brilliant xenon (Xe) discharge lamp operated by microwave-induced electron cyclotron resonance (ECR) for ultrahigh-resolution bulk-sensitive photoemission spectroscopy (PES). We observed at least eight strong radiation lines from neutral or singly ionized Xe atoms in the energy region of 8.4-10.7 eV. The photon flux of the strongest Xe I resonance line at 8.437 eV is comparable to that of the He Ialpha line (21.218 eV) from the He-ECR discharge lamp. Stable operation for more than 300 h is achieved by efficient air-cooling of a ceramic tube in the resonance cavity. The high bulk sensitivity and high-energy resolution of PES using the Xe lines are demonstrated for some typical materials.

  13. Development of high sensitivity and high speed large size blank inspection system LBIS

    Science.gov (United States)

    Ohara, Shinobu; Yoshida, Akinori; Hirai, Mitsuo; Kato, Takenori; Moriizumi, Koichi; Kusunose, Haruhiko

    2017-07-01

    The production of high-resolution flat panel displays (FPDs) for mobile phones today requires the use of high-quality large-size photomasks (LSPMs). Organic light emitting diode (OLED) displays use several transistors on each pixel for precise current control and, as such, the mask patterns for OLED displays are denser and finer than the patterns for the previous generation displays throughout the entire mask surface. It is therefore strongly demanded that mask patterns be produced with high fidelity and free of defect. To enable the production of a high quality LSPM in a short lead time, the manufacturers need a high-sensitivity high-speed mask blank inspection system that meets the requirement of advanced LSPMs. Lasertec has developed a large-size blank inspection system called LBIS, which achieves high sensitivity based on a laser-scattering technique. LBIS employs a high power laser as its inspection light source. LBIS's delivery optics, including a scanner and F-Theta scan lens, focus the light from the source linearly on the surface of the blank. Its specially-designed optics collect the light scattered by particles and defects generated during the manufacturing process, such as scratches, on the surface and guide it to photo multiplier tubes (PMTs) with high efficiency. Multiple PMTs are used on LBIS for the stable detection of scattered light, which may be distributed at various angles due to irregular shapes of defects. LBIS captures 0.3mμ PSL at a detection rate of over 99.5% with uniform sensitivity. Its inspection time is 20 minutes for a G8 blank and 35 minutes for G10. The differential interference contrast (DIC) microscope on the inspection head of LBIS captures high-contrast review images after inspection. The images are classified automatically.

  14. Trapped magnetic field of a superconducting bulk magnet in high- T sub c RE-Ba-Cu-O

    CERN Document Server

    Fujimoto, H; Higuchi, T; Nakamura, Y; Kamijo, H; Nagashima, K; Murakami, M

    1999-01-01

    Superconducting magnets made of high-T sub c superconductors are promising for industrial applications. It is well known that REBa sub 2 Cu sub 3 O sub 7 sub - sub x and LRE (light rare-earth) Ba sub 2 Cu sub 3 O sub 7 sub - sub x superconductors prepared by melt processes have a high critical current density, J sub c , at 77 K and high magnetic fields. Therefore, the materials are very prospective for high magnetic field application as a superconducting permanent/bulk magnet with liquid-nitrogen refrigeration. LREBaCuO bulks, compared with REBaCuO bulks, exhibit a larger J sub c in high magnetic fields and a much improved irreversibility field, H sub i sub r sub r , at 77 K. In this study, we discuss the possibility and trapped field properties of a superconducting bulk magnet, as well as the melt processing for bulk superconductors and their characteristic superconducting properties. One of the applications is a superconducting magnet for the future magnetically levitated (Maglev) train.

  15. The physics of ultra-high-density magnetic recording

    CERN Document Server

    Ek, Johannes; Weller, Dieter

    2001-01-01

    In this book, 17 experts in magnetic recording focus on the underlying physical mechanisms that play crucial roles in medium and transducer development for high areal density disk drives. In 11 chapters, an examination is made of the fundamental physical concepts and their impact on recording mechanisms, with special emphasis on thin-film longitudinal, perpendicular, patterned and nanoparticle media. Theoretical and experimental investigations are presented which serve to enhance our basic understanding of thin-film dynamics, medium dynamics and thermal effects. Fundamental aspects of magnetotransport are discussed and an overview is given of recording head designs.

  16. Design and development of ITER high-frequency magnetic sensor

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Y., E-mail: Yunxing.Ma@iter.org [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Fircroft Engineering, Lingley House, 120 Birchwood Point, Birchwood Boulevard, Warrington, WA3 7QH (United Kingdom); Vayakis, G. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Begrambekov, L.B. [National Research Nuclear University (MEPhI), 115409, Moscow, Kashirskoe shosse 31 (Russian Federation); Cooper, J.-J. [Culham Centre for Fusion Energy (CCFE), Abingdon, Oxfordshire OX14 3DB (United Kingdom); Duran, I. [IPP Prague, Za Slovankou 1782/3, 182 00 Prague 8 (Czech Republic); Hirsch, M.; Laqua, H.P. [Max-Planck-Institut für Plasmaphysik, Teilinstitut Greifswald, Wendelsteinstraße 1, D-17491 Greifswald (Germany); Moreau, Ph. [CEA Cadarache, 13108 Saint Paul lez Durance Cedex (France); Oosterbeek, J.W. [Eindhoven University of Technology (TU/e), PO Box 513, 5600 MB Eindhoven (Netherlands); Spuig, P. [CEA Cadarache, 13108 Saint Paul lez Durance Cedex (France); Stange, T. [Max-Planck-Institut für Plasmaphysik, Teilinstitut Greifswald, Wendelsteinstraße 1, D-17491 Greifswald (Germany); Walsh, M. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France)

    2016-11-15

    Highlights: • ITER high-frequency magnetic sensor system has been designed. • Prototypes have been successfully manufactured. • Manufactured prototypes have been tested in various labs. • Test results experimentally validated the design. - Abstract: High-frequency (HF) inductive magnetic sensors are the primary ITER diagnostic set for Toroidal Alfvén Eigenmodes (TAE) detection, while they also supplement low-frequency MHD and plasma equilibrium measurements. These sensors will be installed on the inner surface of ITER vacuum vessel, operated in a harsh environment with considerable neutron/nuclear radiation and high thermal load. Essential components of the HF sensor system, including inductive coil, electron cyclotron heating (ECH) shield, electrical cabling and termination load, have been designed to meet ITER measurement requirements. System performance (e.g. frequency response, thermal conduction) has been assessed. A prototyping campaign was initiated to demonstrate the manufacturability of the designed components. Prototypes have been produced according to the specifications. A series of lab tests have been performed to examine assembly issues and validate electrical and thermo-mechanical aspects of the design. In-situ microwave radiation test has been conducted in the MISTRAL test facility at IPP-Greifswald to experimentally examine the microwave shielding efficiency and structural integrity of the ECH shield. Low-power microwave attenuation measurement and scanning electron microscopic inspection were conducted to probe and examine the quality of the metal coating on the ECH shield.

  17. Combined passive and active shimming for in vivo MR spectroscopy at high magnetic fields

    Science.gov (United States)

    Juchem, Christoph; Muller-Bierl, Bernd; Schick, Fritz; Logothetis, Nikos K.; Pfeuffer, Josef

    2006-12-01

    The use of high magnetic fields increases the sensitivity and spectral dispersion in magnetic resonance spectroscopy (MRS) of brain metabolites. Practical limitations arise, however, from susceptibility-induced field distortions, which are increased at higher magnetic field strengths. Solutions to this problem include optimized shimming, provided that active, i.e., electronic, shimming can operate over a sufficient range. To meet our shim requirements, which were an order of magnitude greater than the active shim capacity of our 7 T MR system, we developed a combined passive and active shim approach. Simple geometries of ferromagnetic shim elements were derived and numerically optimized to generate a complete set of second-order spherical harmonic shim functions in a modular manner. The major goals of the shim design were maximization of shim field accuracy and ease of practical implementation. The theoretically optimized ferro-shim geometries were mounted on a cylindrical surface and placed inside the magnet bore, surrounding the subject's head and the RF coil. Passive shimming generated very strong shim fields and eliminated the worst of the field distortions, after which the field was further optimized by flexible and highly accurate active shimming. Here, the passive-shimming procedure was first evaluated theoretically, then applied in phantom studies and subsequently validated for in vivo1H MRS in the macaque visual cortex. No artifacts due to the passive shim setup were observed; adjustments were reproducible between sessions. The modularity and the reduction to two pieces per shim term in this study is an important simplification that makes the method applicable also for passive shimming within single sessions. The feasibility of very strong, flexible and high-quality shimming via a combined approach of passive and active shimming is of great practical relevance for MR imaging and spectroscopy at high field strengths where shim power is limited or where

  18. High Frequency Amplitude Detector for GMI Magnetic Sensors

    Directory of Open Access Journals (Sweden)

    Aktham Asfour

    2014-12-01

    Full Text Available A new concept of a high-frequency amplitude detector and demodulator for Giant-Magneto-Impedance (GMI sensors is presented. This concept combines a half wave rectifier, with outstanding capabilities and high speed, and a feedback approach that ensures the amplitude detection with easily adjustable gain. The developed detector is capable of measuring high-frequency and very low amplitude signals without the use of diode-based active rectifiers or analog multipliers. The performances of this detector are addressed throughout the paper. The full circuitry of the design is given, together with a comprehensive theoretical study of the concept and experimental validation. The detector has been used for the amplitude measurement of both single frequency and pulsed signals and for the demodulation of amplitude-modulated signals. It has also been successfully integrated in a GMI sensor prototype. Magnetic field and electrical current measurements in open- and closed-loop of this sensor have also been conducted.

  19. Strong magnetic fields in normal galaxies at high redshift

    Science.gov (United States)

    Bernet, Martin L.; Miniati, Francesco; Lilly, Simon J.; Kronberg, Philipp P.; Dessauges-Zavadsky, Miroslava

    2008-07-01

    The origin and growth of magnetic fields in galaxies is still something of an enigma. It is generally assumed that seed fields are amplified over time through the dynamo effect, but there are few constraints on the timescale. It was recently demonstrated that field strengths as traced by rotation measures of distant (and hence ancient) quasars are comparable to those seen today, but it was unclear whether the high fields were in the unusual environments of the quasars themselves or distributed along the lines of sight. Here we report high-resolution spectra that demonstrate that the quasars with strong MgII absorption lines are unambiguously associated with larger rotation measures. Because MgII absorption occurs in the haloes of normal galaxies along the sightlines to the quasars, this association requires that organized fields of surprisingly high strengths are associated with normal galaxies when the Universe was only about one-third of its present age.

  20. Magnetic Implosion for Novel Strength Measurements at High Strain Rates

    Energy Technology Data Exchange (ETDEWEB)

    Lee, H.; Preston, D.L.; Bartsch, R.R.; Bowers, R.L.; Holtkamp, D.; Wright, B.L.

    1998-10-19

    Recently Lee and Preston have proposed to use magnetic implosions as a new method for measuring material strength in a regime of large strains and high strain rates inaccessible to previously established techniques. By its shockless nature, this method avoids the intrinsic difficulties associated with an earlier approach using high explosives. The authors illustrate how the stress-strain relation for an imploding liner can be obtained by measuring the velocity and temperature history of its inner surface. They discuss the physical requirements that lead us to a composite liner design applicable to different test materials, and also compare the code-simulated prediction with the measured data for the high strain-rate experiments conducted recently at LANL. Finally, they present a novel diagnostic scheme that will enable us to remove the background in the pyrometric measurement through data reduction.

  1. Dual-Modality Imaging Probes with High Magnetic Relaxivity and Near-Infrared Fluorescence Based Highly Aminated Mesoporous Silica Nanoparticles

    Directory of Open Access Journals (Sweden)

    Zhu Fei-Peng

    2016-01-01

    Full Text Available Dual-modal imaging by combining magnetic resonance (MR and near-infrared (NIR fluorescence can integrate the advantages of high-resolution anatomical imaging with high sensitivity in vivo fluorescent imaging, which is expected to play a significant role in biomedical researches. Here we report a dual-modality imaging probe (NIR/MR-MSNs fabricated by conjugating NIR fluorescent heptamethine dyes (IR-808 and MR contrast agents (Gd-DTPA within highly aminated mesoporous silica nanoparticles (MSNs-NH2. The dual-modality imaging probes NIR/MR-MSNs possess a size of ca. 120 nm. The NIR/MR-MSNs show not only near-infrared fluorescence imaging property with an emission peak at 794 nm, but also highly MR T1 relaxivity of 14.54 mM−1 s−1, which is three times more than Gd-DTPA. In vitro experiment reveals high uptake and retention abilities of the nanoprobes, while cell viability assay demonstrates excellent cytocompatibility of the dual-modality imaging probe. After intratumor injection with the NIR/MR-MSNs, MR imaging shows clear anatomical border of the enhanced tumor region while NIR fluorescence exhibits high sensitive tumor detection ability. These intriguing features suggest that this newly developed dual-modality imaging probes have great potential in biomedical imaging.

  2. Construction of a high-performance magnetic enzyme nanosystem for rapid tryptic digestion

    OpenAIRE

    Gong Cheng; Si-Yang Zheng

    2014-01-01

    A magnetic enzyme nanosystem have been designed and constructed by a polydopamine (PDA)-modification strategy. The magnetic enzyme nanosystem has well defined core-shell structure and a relatively high saturation magnetization (Ms) value of 48.3 emu g−1. The magnetic enzyme system can realize rapid, efficient and reusable tryptic digestion of proteins by taking advantage of its magnetic core and biofunctional shell. Various standard proteins (e.g. cytochrome C (Cyt-C), myoglobin (MYO) and bov...

  3. High-field magnetic transition in Er sub 2 Fe sub 14 B

    Energy Technology Data Exchange (ETDEWEB)

    Radwanski, R.J.; Boer, F.R. de (Natuurkundig Lab., Univ. van Amsterdam (Netherlands)); Zhong, X.P.; Yang, F.M.; Li, J.Y. (Magnetism Lab., Inst. of Physics, Academia Sinica, Beijing (China)); Kohashi, T.; Ono, M.; Date, M. (Dept. of Physics, Osaka Univ. (Japan)); Yamagishi, A. (Research Center for Extreme Materials, Osaka Univ. (Japan))

    1991-10-01

    Field-induced transitions in quasi-ternary Er{sub 2}Fe{sub 14}B compounds have been revealed by means of magnetization measurements at high magnetic fields. The high-field studies for Er{sub 2}Fe{sub 14}B, in particular the modest differential high-field susceptibility and the formation of a non-collinear magnetic structure at 42 T, do not confirm the substantial canted magnetic structure at low fields. (orig.).

  4. High-resolution melting analysis (HRMA): a highly sensitive inexpensive genotyping alternative for population studies.

    Science.gov (United States)

    Smith, B L; Lu, C-P; Alvarado Bremer, J R

    2010-01-01

    High-resolution melting analysis (HRMA) is a highly sensitive closed-tube genotyping method used primarily in clinical studies. As the method is rapid, inexpensive and amenable to high throughput, we decided to investigate its applicability to population studies. Small amplicons and unlabelled probes were used to genotype the nuclear genes, lactate dehydrogenase-A (ldh-A), myosin light chain-2 (mlc-2), acidic ribosomal phosphoprotein P0 (ARP) and calmodulin (CaM) in populations of swordfish, Xiphias gladius. Results indicate that HRMA is a powerful genotyping tool to study wild populations. © 2009 Blackwell Publishing Ltd.

  5. An improved electrochemiluminescence polymerase chain reaction method for highly sensitive detection of plant viruses

    Energy Technology Data Exchange (ETDEWEB)

    Tang Yabing [MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, South China Normal University, Guangzhou 510631 (China); Xing Da [MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, South China Normal University, Guangzhou 510631 (China)]. E-mail: xingda@scnu.edu.cn; Zhu Debin [MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, South China Normal University, Guangzhou 510631 (China); Liu Jinfeng [MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, South China Normal University, Guangzhou 510631 (China)

    2007-01-23

    Recently, we have reported an electrochemiluminescence polymerase chain reaction (ECL-PCR) method for detection of genetically modified organisms. The ECL-PCR method was further improved in the current study by introducing a multi-purpose nucleic acid sequence that was specific to the tris(bipyridine) ruthenium (TBR) labeled probe, into the 5' terminal of the primers. The method was applied to detect plant viruses. Conserved sequence of the plant viruses was amplified by PCR. The product was hybridized with a biotin labeled probe and a TBR labeled probe. The hybridization product was separated by streptavidin-coated magnetic beads, and detected by measuring the ECL signals of the TBR labeled. Under the optimized conditions, the experiment results show that the detection limit is 50 fmol of PCR products, and the signal-to-noise ratio is in excess of 14.6. The method was used to detect banana streak virus, banana bunchy top virus, and papaya leaf curl virus. The experiment results show that this method could reliably identity viruses infected plant samples. The improved ECL-PCR approach has higher sensitivity and lower cost than previous approach. It can effectively detect the plant viruses with simplicity, stability, and high sensitivity.

  6. An induction heating device using planar coil with high amplitude alternating magnetic fields for magnetic hyperthermia.

    Science.gov (United States)

    Wu, Zuhe; Zhuo, Zihang; Cai, Dongyang; Wu, Jian'an; Wang, Jie; Tang, Jintian

    2015-01-01

    Induction heating devices using the induction coil and magnetic nanoparticles (MNPs) are the way that the magnetic hyperthermia is heading. To facilitate the induction heating of in vivo magnetic nanoparticles in hyperthermia experiments on large animals. An induction heating device using a planar coil was designed with a magnetic field frequency of 328 kHz. The coil's magnetic field distribution and the device's induction heating performance on different concentrations of magnetic nanoparticles were measured. The alternating magnetic field produced in the axis position 165 mm away from the coil center is 40 Gs in amplitude; magnetic nanoparticles with a concentration higher than 80 mg. mL-1 can be heated up rapidly. Our results demonstrate that the device can be applied not only to in vitro and in small animal experiments of magnetic hyperthermia using MNPs, but also in large animal experiments.

  7. High-performance iron oxide nanoparticles for magnetic particle imaging - guided hyperthermia (hMPI)

    Science.gov (United States)

    Bauer, Lisa M.; Situ, Shu F.; Griswold, Mark A.; Samia, Anna Cristina S.

    2016-06-01

    Magnetic particle imaging (MPI) is an emerging imaging modality that allows the direct and quantitative mapping of iron oxide nanoparticles. In MPI, the development of tailored iron oxide nanoparticle tracers is paramount to achieving high sensitivity and good spatial resolution. To date, most MPI tracers being developed for potential clinical applications are based on spherical undoped magnetite nanoparticles. For the first time, we report on the systematic investigation of the effects of changes in chemical composition and shape anisotropy on the MPI performance of iron oxide nanoparticle tracers. We observed a 2-fold enhancement in MPI signal through selective doping of magnetite nanoparticles with zinc. Moreover, we demonstrated focused magnetic hyperthermia heating by adapting the field gradient used in MPI. By saturating the iron oxide nanoparticles outside of a field free region (FFR) with an external static field, we can selectively heat a target region in our test sample. By comparing zinc-doped magnetite cubic nanoparticles with undoped spherical nanoparticles, we could show a 5-fold improvement in the specific absorption rate (SAR) in magnetic hyperthermia while providing good MPI signal, thereby demonstrating the potential for high-performance focused hyperthermia therapy through an MPI-guided approach (hMPI).Magnetic particle imaging (MPI) is an emerging imaging modality that allows the direct and quantitative mapping of iron oxide nanoparticles. In MPI, the development of tailored iron oxide nanoparticle tracers is paramount to achieving high sensitivity and good spatial resolution. To date, most MPI tracers being developed for potential clinical applications are based on spherical undoped magnetite nanoparticles. For the first time, we report on the systematic investigation of the effects of changes in chemical composition and shape anisotropy on the MPI performance of iron oxide nanoparticle tracers. We observed a 2-fold enhancement in MPI signal

  8. [Survey of risks related to static magnetic fields in ultra high field MRI].

    Science.gov (United States)

    Möller, H E; von Cramon, D Y

    2008-04-01

    In magnetic resonance imaging (MRI), substantial improvements with respect to sensitivity are expected due to the development of so-called ultra high field scanners, i. e., whole-body scanners with a magnetic field strength of 7 T or above. Users of this technology need to evaluate this benefit for potential risks since commercially available systems are not certified as a medical device for human use. This review provides a detailed survey of static field bioeffects related to the exposure of subjects being scanned, to occupational exposure, and to exposure of the general public under consideration of current standards and directives. According to present knowledge, it is not expected that exposure of human subjects to static magnetic fields of 7 T implies a specific risk of damage or disease provided that known contraindications are observed. The available database does not permit definition of exact thresholds for harmful effects. However, experience from previous application of ultra high field MRI indicates that transient phenomena, such as vertigo, nausea, metallic taste, or magneto-phosphenes, are more frequently observed. In particular, movements in the field or the gradient of the fringe field seem to lead to detectable effects. Besides such observations, there is a strong demand for systematic investigation of potential interaction mechanisms related to static field exposure during MRI examinations.

  9. High incidence of sensitization to ornamental plants in allergic rhinitis.

    Science.gov (United States)

    Mahillon, V; Saussez, S; Michel, O

    2006-09-01

    A few indoor plants have been described as potential allergens, in single case reports of allergic rhinitis. There is no data evaluating the prevalence of allergic sensitization to these plants. The relationship between owning indoor ornamental plants with the risk to be sensitized has been evaluated in atopic rhinitis. A group of 59 patients with allergic rhinitis were submitted to skin prick tests (SPT) using both the leafs of their own plant and commercial extracts of the most frequent airborne allergens. A control group of 15 healthy subjects was tested with the same allergens. While no subject from the control group developed a significant SPT to any of the tested plants, 78% of allergic rhinitis had positive SPT to at least one plant, the most frequent sensitization being Ficus benjamina, yucca, ivy and palm tree. In allergic rhinitis, indoor plants should be considered as potential allergens.

  10. Development of High Temperature/High Sensitivity Novel Chemical Resistive Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Chunrui [Univ. of Texas, San Antonio, TX (United States); Enriquez, Erik [Univ. of Texas, San Antonio, TX (United States); Wang, Haibing [Univ. of Texas, San Antonio, TX (United States); Xu, Xing [Univ. of Texas, San Antonio, TX (United States); Bao, Shangyong [Univ. of Texas, San Antonio, TX (United States); Collins, Gregory [Univ. of Texas, San Antonio, TX (United States)

    2013-08-13

    The research has been focused to design, fabricate, and develop high temperature/high sensitivity novel multifunctional chemical sensors for the selective detection of fossil energy gases used in power and fuel systems. By systematically studying the physical properties of the LnBaCo2O5+d (LBCO) [Ln=Pr or La] thin-films, a new concept chemical sensor based high temperature chemical resistant change has been developed for the application for the next generation highly efficient and near zero emission power generation technologies. We also discovered that the superfast chemical dynamic behavior and an ultrafast surface exchange kinetics in the highly epitaxial LBCO thin films. Furthermore, our research indicates that hydrogen can superfast diffuse in the ordered oxygen vacancy structures in the highly epitaxial LBCO thin films, which suggest that the LBCO thin film not only can be an excellent candidate for the fabrication of high temperature ultra sensitive chemical sensors and control systems for power and fuel monitoring systems, but also can be an excellent candidate for the low temperature solid oxide fuel cell anode and cathode materials.

  11. Magnetically-related properties of bismuth containing high Tc superconductors

    Science.gov (United States)

    Vezzoli, Gary C.; Chen, M. F.; Craver, F.; Safari, A.; Moon, B. M.; Lalevic, B.; Burke, Terence; Shoga, M.

    1990-08-01

    The effect of magnetic fields to 15 T on electrical resistance has been measured for the BiSrCaCuO superconductor at precise temperatures during the transition to the superconducting state from pre-onset conditions to essentially zero resistance conditions. The results show that the temperature at which the magnetic field causes a divergence in the resistance versus 1000/ T curve is approximately the same temperature as the value at which, during cooling, the positive Hall coefficient begins its abrupt descent to zero. This temperature gives the best measure of Tc. It is also shown that small oscillations of low frequency start near onset conditions, the amplitude of which at a given temperature is B-field dependent. Additionally, Hall effect studies as a function of temperature at 4 T in three separate experiments (including high Tc BiSrCaCu PbO of > 90% theoretical density) show that sharp delta-function-like peaks in + RH are observed near Tc and are superimposed on a broader maximum. The Hall data are explicable in terms of exciton formation and ionization. The bound holes associated with these excitons are believed to be the mediators producing Cooper-pairing, and scale very well with Tc for all the known high Tc oxides.

  12. Rapid, high sensitivity, point-of-care test for cardiac troponin based on optomagnetic biosensor

    NARCIS (Netherlands)

    Dittmer, W.U.; Evers, T.H.; Hardeman, W.M.; Huijnen-Keur, W.M.; Kamps, R.; De Kievit, P.; Neijzen, J.H.M.; Sijbers, M.J.J.; Nieuwenhuis, J.H.; Hefti, M.H.; Dekkers, D.; Martens, M.

    2010-01-01

    BACKGROUND: We present a handheld integrated device based on a novel magnetic-optical technology for the sensitive detection of cardiactroponin I, a biomarker for the positive diagnosis of myocardial infarct, in a finger-prick blood sample. The test can be performed with a turn-around time of 5

  13. Nanoparticle Aggregate-Based Fluorescence Enhancement for Highly Sensitive and Reproducible Detection of DNA

    NARCIS (Netherlands)

    Annink, C.; Gill, Ron

    2014-01-01

    Sensitive detection of DNA at the sub picomolar range is demonstrated using a magnetic bead sandwich hybridization assay coupled with surface-enhanced fluorescence (SEF)-based amplification. Unlike enzymatic amplification, the SEF amplification step does not add any additional background to the

  14. High-speed high-sensitivity infrared spectroscopy using mid-infrared swept lasers (Conference Presentation)

    Science.gov (United States)

    Childs, David T. D.; Groom, Kristian M.; Hogg, Richard A.; Revin, Dmitry G.; Cockburn, John W.; Rehman, Ihtesham U.; Matcher, Stephen J.

    2016-03-01

    Infrared spectroscopy is a highly attractive read-out technology for compositional analysis of biomedical specimens because of its unique combination of high molecular sensitivity without the need for exogenous labels. Traditional techniques such as FTIR and Raman have suffered from comparatively low speed and sensitivity however recent innovations are challenging this situation. Direct mid-IR spectroscopy is being speeded up by innovations such as MEMS-based FTIR instruments with very high mirror speeds and supercontinuum sources producing very high sample irradiation levels. Here we explore another possible method - external cavity quantum cascade lasers (EC-QCL's) with high cavity tuning speeds (mid-IR swept lasers). Swept lasers have been heavily developed in the near-infrared where they are used for non-destructive low-coherence imaging (OCT). We adapt these concepts in two ways. Firstly by combining mid-IR quantum cascade gain chips with external cavity designs adapted from OCT we achieve spectral acquisition rates approaching 1 kHz and demonstrate potential to reach 100 kHz. Secondly we show that mid-IR swept lasers share a fundamental sensitivity advantage with near-IR OCT swept lasers. This makes them potentially able to achieve the same spectral SNR as an FTIR instrument in a time x N shorter (N being the number of spectral points) under otherwise matched conditions. This effect is demonstrated using measurements of a PDMS sample. The combination of potentially very high spectral acquisition rates, fundamental SNR advantage and the use of low-cost detector systems could make mid-IR swept lasers a powerful technology for high-throughput biomedical spectroscopy.

  15. Magnetoencephalography with a Cs-based high-sensitivity compact atomic magnetometer

    Science.gov (United States)

    Sheng, Jingwei; Wan, Shuangai; Sun, Yifan; Dou, Rongshe; Guo, Yuhao; Wei, Kequan; He, Kaiyan; Qin, Jie; Gao, Jia-Hong

    2017-09-01

    In recent years, substantial progress has been made in developing a new generation of magnetoencephalography (MEG) with a spin-exchange relaxation free (SERF)-based atomic magnetometer (AM). An AM employs alkali atoms to detect weak magnetic fields. A compact AM array with high sensitivity is crucial to the design; however, most proposed compact AMs are potassium (K)- or rubidium (Rb)-based with single beam configurations. In the present study, a pump-probe two beam configuration with a Cesium (Cs)-based AM (Cs-AM) is introduced to detect human neuronal magnetic fields. The length of the vapor cell is 4 mm, which can fully satisfy the need of designing a compact sensor array. Compared with state-of-the-art compact AMs, our new Cs-AM has two advantages. First, it can be operated in a SERF regime, requiring much lower heating temperature, which benefits the sensor with a closer distance to scalp due to ease of thermal insulation and less electric heating noise interference. Second, the two-beam configuration in the design can achieve higher sensitivity. It is free of magnetic modulation, which is necessary in one-beam AMs; however, such modulation may cause other interference in multi-channel circumstances. In the frequency band between 10 Hz and 30 Hz, the noise level of the proposed Cs-AM is approximately 10 f T/Hz1/2, which is comparable with state-of-the-art K- or Rb-based compact AMs. The performance of the Cs-AM was verified by measuring human auditory evoked fields (AEFs) in reference to commercial superconducting quantum interference device (SQUID) channels. By using a Cs-AM, we observed a clear peak in AEFs around 100 ms (M100) with a much larger amplitude compared with that of a SQUID, and the temporal profiles of the two devices were in good agreement. The results indicate the possibility of using the compact Cs-AM for MEG recordings, and the current Cs-AM has the potential to be designed for multi-sensor arrays and gradiometers for future neuroscience

  16. High sensitivity PCR assay in plastic micro reactors.

    Science.gov (United States)

    Yang, Jianing; Liu, Yingjie; Rauch, Cory B; Stevens, Rauch L; Liu, Randall H; Lenigk, Robin; Grodzinski, Piotr

    2002-11-01

    Small volume operation and rapid thermal cycling have been subjects of numerous reports in micro reactor chip development. Sensitivity aspects of the micro PCR reactor have not been studied in detail, however, despite the fact that detection of rare targets or trace genomic material from clinical and/or environmental samples has been a great challenge for microfluidic devices. In this study, a serpentine shaped thin (0.75 mm) polycarbonate plastic PCR micro reactor was designed, constructed, and tested for not only its rapid operation and efficiency, but also its detection sensitivity and specificity, in amplification of Escherichia coli (E. coli) K12-specific gene fragment. At a template concentration as low as 10 E. coli cells (equivalent to 50 fg genomic DNA), a K12-specific gene product (221 bp) was adequately amplified with a total of 30 cycles in 30 min. Sensitivity of the PCR micro reactor was demonstrated with its ability to amplify K12-specific gene from 10 cells in the presence of 2% blood. Specificity of the polycarbonate PCR micro reactor was also proven through multiplex PCR and/or amplification of different pathogen-specific genes. This is, to our knowledge, the first systematic study of assay sensitivity and specificity performed in plastic, disposable micro PCR devices.

  17. New Highly-Sensitive Ultra-Performance Liquid Chromatography ...

    African Journals Online (AJOL)

    Purpose: To develop and validate a simple, rapid, sensitive and specific ultraperformance liquid chromatography mass spectrometry method for the quantification of the angiotensin II receptor antagonist, telmisartan (TEL), in human plasma. Methods: After simple protein precipitation using acetonitrile and methanol, TEL and ...

  18. Ultra-High Intensity Magnetic Field Generation in Dense Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Fisch, Nathaniel J. [Princeton Univ., NJ (United States)

    2014-01-08

    The main objective of this grant proposal was to explore the efficient generation of intense currents. Whereas the efficient generation of electric current in low-­energy-­density plasma has occupied the attention of the magnetic fusion community for several decades, scant attention has been paid to carrying over to high-­energy-­density plasma the ideas for steady-­state current drive developed for low-­energy-­density plasma, or, for that matter, to inventing new methodologies for generating electric current in high-­energy-­density plasma. What we proposed to do was to identify new mechanisms to accomplish current generation, and to assess the operation, physics, and engineering basis of new forms of current drive in regimes appropriate for new fusion concepts.

  19. Raman spectroscopy of graphite in high magnetic fields

    Science.gov (United States)

    Kim, Younghee; Lombardo, Antonio; Kalugin, Nikolai G.; Kono, Junichiro; Ferrari, Andrea C.; Smirnov, Dmitry

    2011-03-01

    Recently, much attention has been paid to electron-phonon coupling in graphene. In particular, significant re-normalization and broadening of long-wavelength optical phonons are predicted to occur through resonant interaction with Landau-quantized Dirac fermions. We report here on a high-field magneto-Raman spectroscopy study of highly-oriented pyrolytic graphite (HOPG) and natural graphite at temperatures down to 5 K and in magnetic fields up to 45 T. The E2 g graphite phonon line exhibits anticrossing-like behavior at approximately 30 T, which we attribute to the magneto-phonon resonance (MPR) of graphite's massless holes at the H-point. Additionally, we observed features related to inter-Landau-level transitions at the K-point of graphite. We also observed weak graphene-like signatures of MPR, indicating the existence of graphene flakes on the graphite surface.

  20. Detecting the sensitivity of magnetic response on different pollution sources--A case study from typical mining cities in northwestern China.

    Science.gov (United States)

    Wang, Bo; Xia, Dunsheng; Yu, Ye; Jia, Jia; Nie, Yan; Wang, Xin

    2015-12-01

    Rapid monitoring and discriminating different anthropogenic pollution is a key scientific issue. To detect the applicability and sensitivity of magnetic measurements for evaluating different industrial pollution in urban environment, characteristics of topsoil from three typical fast developing industrial cities (Jinchang, Baiyin and Jiayuguan in Gansu province, northwestern China) were studied by magnetic and geochemical analyses. The results showed that magnetic susceptibility was enhanced near industrial areas, and PSD-MD magnetite dominated the magnetic properties. Magnetic concentration parameters (χlf, SIRM, and χARM) showed different correlations with heavy metals and PLI in the three cities, indicating significantly different magnetic response to different pollution sources. Principal component analysis showed that ferrimagnetic minerals coexist with heavy metals of Fe, As, Cu, Pb, and Zn in Baiyin and Fe, V, Cu, Mn, Pb, and Cr in Jiayuguan. Fuzzy cluster analysis and regression analysis further indicated that the sensitivity of magnetic monitoring to fuel dust is higher than that to mineral dust near non-ferrous metal smelters, and fossil fuel consumption is an important factor for increasing magnetite content. In all the three cities, the sensitivity of magnetic monitoring to pollutants from steel plants is much higher than that from non-ferrous metal plants. Therefore, magnetic proxies provide a rapid means for detecting heavy metal contamination caused by multi-anthropogenic pollution sources in a large scale area, however, the sensitivity was controlled by pollution sources. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Static high-gradient magnetic fields affect the functionality of monocytic cells

    Czech Academy of Sciences Publication Activity Database

    Syrovets, T.; Schmidt, Z.; Buechele, B.; Zablotskyy, Vitaliy A.; Dejneka, Alexandr; Dempsey, N.; Simmet, T.

    2014-01-01

    Roč. 28, č. 1 (2014), s. 1-2 ISSN 0892-6638 Institutional support: RVO:68378271 Keywords : static high-gradient * magnet ic fields * affect the functionality * monocytic cells Subject RIV: BM - Solid Matter Physics ; Magnet ism

  2. A new method of determining the reversible magnetization loop of bulk high-temperature superconductors

    NARCIS (Netherlands)

    Ermolaev, YS; Rudnev, IA

    2004-01-01

    A new method of calculation of the magnetization loop of bulk high-temperature superconductors is proposed which employs the results of measurements of the magnetic levitation force. (C) 2004 MAIK "Nauka / Interperiodica".

  3. Design of High Performance Permanent-Magnet Synchronous Wind Generators

    Directory of Open Access Journals (Sweden)

    Chun-Yu Hsiao

    2014-11-01

    Full Text Available This paper is devoted to the analysis and design of high performance permanent-magnet synchronous wind generators (PSWGs. A systematic and sequential methodology for the design of PMSGs is proposed with a high performance wind generator as a design model. Aiming at high induced voltage, low harmonic distortion as well as high generator efficiency, optimal generator parameters such as pole-arc to pole-pitch ratio and stator-slot-shoes dimension, etc. are determined with the proposed technique using Maxwell 2-D, Matlab software and the Taguchi method. The proposed double three-phase and six-phase winding configurations, which consist of six windings in the stator, can provide evenly distributed current for versatile applications regarding the voltage and current demands for practical consideration. Specifically, windings are connected in series to increase the output voltage at low wind speed, and in parallel during high wind speed to generate electricity even when either one winding fails, thereby enhancing the reliability as well. A PMSG is designed and implemented based on the proposed method. When the simulation is performed with a 6 Ω load, the output power for the double three-phase winding and six-phase winding are correspondingly 10.64 and 11.13 kW. In addition, 24 Ω load experiments show that the efficiencies of double three-phase winding and six-phase winding are 96.56% and 98.54%, respectively, verifying the proposed high performance operation.

  4. High magnetic field properties of Fe-pnictide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kurth, Fritz

    2015-11-20

    The recent discovery of high-temperature superconductivity in Fe-based materials triggered worldwide efforts to investigate their fundamental properties. Despite a lot of similarities to cuprates and MgB{sub 2}, important differences like near isotropic behaviour in contrast to cuprates and the peculiar pairing symmetry of the order parameter (OP) have been reported. The OP symmetry of Fe-based superconductors (FBS) was theoretically predicted to be of so-called s± state prior to various experimental works. Still, most of the experimental results favour the s± scenario; however, definitive evidence has not yet been reported. Although no clear understanding of the superconducting mechanisms yet exists, potential applications such as high-field magnets and Josephson devices have been explored. Indeed, a lot of reports about FBS tapes, wires, and even SQUIDs have been published to this date. In this thesis, the feasibility of high-field magnet applications of FBS is addressed by studying their transport properties, involving doped BaFe{sub 2}As{sub 2} (Ba-122) and LnFeAs(O,F) [Ln=Sm and Nd]. Particularly, it is important to study physical properties in a sample form (i.e. thin films) that is close to the conditions found in applications. However, the realisation of epitaxial FBS thin films is not an easy undertaking. Recent success in growing epitaxial FBS thin films opens a new avenue to delve into transport critical current measurements. The information obtained through this research will be useful for exploring high-field magnet applications. This thesis consists of 7 chapters: Chapter 1 describes the motivation of this study, the basic background of superconductivity, and a brief summary of the thin film growth of FBS. Chapter 2 describes experimental methods employed in this study. Chapter 3 reports on the fabrication of Co-doped Ba-122 thin films on various substrates. Particular emphasis lies on the discovery of fluoride substrates to be beneficial for

  5. MAGNET

    CERN Multimedia

    Benoit Curé.

    The magnet operation restarted end of June this year. Quick routine checks of the magnet sub-systems were performed at low current before starting the ramps up to higher field. It appeared clearly that the end of the field ramp down to zero was too long to be compatible with the detector commissioning and operations plans. It was decided to perform an upgrade to keep the ramp down from 3.8T to zero within 4 hours. On July 10th, when a field of 1.5T was reached, small movements were observed in the forward region support table and it was decided to fix this problem before going to higher field. At the end of July the ramps could be resumed. On July 28th, the field was at 3.8T and the summer CRAFT exercise could start. This run in August went smoothly until a general CERN wide power cut took place on August 3rd, due to an insulation fault on the high voltage network outside point 5. It affected the magnet powering electrical circuit, as it caused the opening of the main circuit breakers, resulting in a fast du...

  6. MAGNET

    CERN Multimedia

    B. Curé

    2013-01-01

    The magnet is fully stopped and at room temperature. The maintenance works and consolidation activities on the magnet sub-systems are progressing. To consolidate the cryogenic installation, two redundant helium compressors will be installed as ‘hot spares’, to avoid the risk of a magnet downtime in case of a major failure of a compressor unit during operation. The screw compressors, their motors, the mechanical couplings and the concrete blocks are already available and stored at P5. The metallic structure used to access the existing compressors in SH5 will be modified to allow the installation of the two redundant ones. The plan is to finish the installation and commissioning of the hot spare compressors before the summer 2014. In the meantime, a bypass on the high-pressure helium piping will be installed for the connection of a helium drier unit later during the Long Shutdown 1, keeping this installation out of the schedule critical path. A proposal is now being prepared for the con...

  7. High field magnet program at Brookhaven National Laboratory

    CERN Document Server

    Ghosh, A; Muratore, J; Parker, B; Sampson, W; Wanderer, P J; Willen, E

    2000-01-01

    The magnet program at Brookhaven National Laboratory (BNL) is focussed on superconducting magnets for particle accelerators. The effort includes magnet production at the laboratory and in industry, magnet R&D, and test facilities for magnets and superconductors. Nearly 2000 magnets-dipoles, quadrupoles, sextupoles and correctors for the arc and insertion regions-were produced for the Relativistic Heavy Ion Collider (RHIC), which is being commissioned. Currently, production of helical dipoles for the polarized proton program at RHIC, insertion region dipoles for the Large Hadron Collider (LHC) at CERN, and an insertion magnet system for the Hadron-Elektron-Ring- Analage (HERA) collider at Deutsches Elektronen-Synchrotron (DESY) is underway. The R&D effort is exploring dipoles with fields above 10 T for use in post-LHC colliders. Brittle superconductors-Nb/sub 3/Sn or HTS-are being used for these magnets. The superconductor test facility measures short-sample currents and other characteristics of sample...

  8. Optic Tract Edema: A Highly Specific Magnetic Resonance Imaging Finding for the Diagnosis of Craniopharyngiomas

    Energy Technology Data Exchange (ETDEWEB)

    Hirunpat, S.; Tanomkiat, W.; Sriprung, H.; Chetpaophan, J. [Prince of Songkla Univ., Hat Yai (Thailand). Dept. of Radiology and Epidemiology Unit

    2005-07-01

    Purpose: To clarify the accuracy, sensitivity, and specificity of optic tract edema in the diagnosis of craniopharyngiomas. Material and Methods: Preoperative magnetic resonance images (MRIs) of 49 patients (between May 1996 and March 2003) who had a diagnosis of parasellar masses were blindly reviewed by two radiologists. The spread of edema surrounding the tumor on the coronal TSE T2-weighted images was analyzed. Sensitivity and specificity were calculated based on the numbers in this series and also pooled numbers from previous known reported series. Results: Edema along the optic tracts was detected in 7 of 1 craniopharyngiomas, giving a sensitivity of 63.6% (95% CI{approx_equal}30.8-89.1) for our series and 66.7% (95% CI{approx_equal}47.2-82.7) for the pooled numbers. The specificity was 00% (95% CI{approx_equal}90.7-100.0) for our series and 93.9% (95% CI{approx_equal}87.1-97.7) for the pooled numbers. None of the 28 pituitary macroadenomas, 4 meningiomas, 2 hypothalamic astrocytomas, 2 germinomas, mixed-germ cell tumor and arachnoid cyst in our study showed edema of the optic pathways. Conclusion: Optic tract edema, commonly seen in craniopharyngiomas, is a useful MR finding for distinguishing craniopharyngiomas from other parasellar tumors with considerable sensitivity and high specificity.

  9. Plasmoid Instability in High-Lundquist-Number Magnetic Reconnection

    Science.gov (United States)

    Huang, Yi-Min

    2012-10-01

    Our understanding of magnetic reconnection in resistive magnetohydrodynamics has gone through a fundamental change in recent years. The conventional wisdom is that magnetic reconnection mediated by resistivity is slow in high Lundquist (S) plasmas, due to the S-1/2 scaling of reconnection rate predicted by the classical Sweet-Parker theory. However, recent studies showed that when S exceeds a critical value ˜10^4, the Sweet-Parker current sheet is unstable to a super-Alfvenic plasmoid instability, with a growth rate that increases with S [1]. Consequently, the reconnection layer changes to a chain of plasmoids connected by secondary current sheets that, in turn, may become unstable again. Eventually the reconnection layer will tend to a statistical steady state governed by complex dynamics of plasmoid formation and plasmoid loss due to advection and coalescence. The averaged reconnection rate in this regime is nearly independent of S [2,3], and the distribution function f(ψ) of magnetic fluxes ψ in plasmoids follows a power-law f˜&-1circ;. When Hall effects are included, the plasmoid instability may trigger onset of Hall reconnection even when the conventional criterion for onset is not satisfied. In addition to the usual single X-point topology of Hall reconnection, our large-scale resistive Hall MHD simulations reveal a novel intermediate regime, where formation of new plasmoids is observed after onset of Hall reconnection [4]. Qualitatively similar results have also been found when resistivity is replaced by hyper-resistivity. Our findings suggest that plasmoid formation may be a generic feature of magnetic reconnection in large systems, regardless of the mechanism of breaking the frozen-in condition. (In collaboration with A. Bhattacharjee and B. P. Sullivan).[4pt] [1] N. F. Loureiro, A. A. Schekochihin, and S. C. Cowley, Phys. Plasmas 14, 100703 (2007).[0pt] [2] A. Bhattacharjee, Y.-M. Huang, H. Yang, and B. Rogers, Phys. Plasmas 16, 112102 (2009).[0pt] [3

  10. Highly sensitive BTX detection using surface functionalized QCM sensor

    Energy Technology Data Exchange (ETDEWEB)

    Bozkurt, Asuman Aşıkoğlu; Özdemir, Okan; Altındal, Ahmet, E-mail: altindal@yildiz.edu.tr [Department of Physics, Yildiz Technical University, Davutpasa, 34210 Istanbul (Turkey)

    2016-03-25

    A novel organic compound was designed and successfully synthesized for the fabrication of QCM based sensors to detect the low concentrations of BTX gases in indoor air. The effect of the long-range electron orbital delocalization on the BTX vapour sensing properties of azo-bridged Pcs based chemiresistor-type sensors have also been investigated in this work. The sensing behaviour of the film for the online detection of volatile organic solvent vapors was investigated by utilizing an AT-cut quartz crystal resonator. It was observed that the adsorption of the target molecules on the coating surface cause a reversible negative frequency shift of the resonator. Thus, a variety of solvent vapors can be detected by using the phthalocyanine film as sensitive coating, with sensitivity in the ppm range and response times in the order of several seconds depending on the molecular structure of the organic solvent.

  11. Extremely high frequency sensitivity in a 'simple' ear.

    Science.gov (United States)

    Moir, Hannah M; Jackson, Joseph C; Windmill, James F C

    2013-08-23

    An evolutionary war is being played out between the bat, which uses ultrasonic calls to locate insect prey, and the moth, which uses microscale ears to listen for the approaching bat. While the highest known frequency of bat echolocation calls is 212 kHz, the upper limit of moth hearing is considered much lower. Here, we show that the greater wax moth, Galleria mellonella, is capable of hearing ultrasonic frequencies approaching 300 kHz; the highest frequency sensitivity of any animal. With auditory frequency sensitivity that is unprecedented in the animal kingdom, the greater wax moth is ready and armed for any echolocation call adaptations made by the bat in the on-going bat-moth evolutionary war.

  12. Extremely high frequency sensitivity in a ‘simple’ ear

    Science.gov (United States)

    Moir, Hannah M.; Jackson, Joseph C.; Windmill, James F. C.

    2013-01-01

    An evolutionary war is being played out between the bat, which uses ultrasonic calls to locate insect prey, and the moth, which uses microscale ears to listen for the approaching bat. While the highest known frequency of bat echolocation calls is 212 kHz, the upper limit of moth hearing is considered much lower. Here, we show that the greater wax moth, Galleria mellonella, is capable of hearing ultrasonic frequencies approaching 300 kHz; the highest frequency sensitivity of any animal. With auditory frequency sensitivity that is unprecedented in the animal kingdom, the greater wax moth is ready and armed for any echolocation call adaptations made by the bat in the on-going bat–moth evolutionary war. PMID:23658005

  13. Highly Sensitive Cadmium Concentration Sensor Using Long Period Grating

    Directory of Open Access Journals (Sweden)

    A. S. Lalasangi

    2011-08-01

    Full Text Available In this paper we have proposed a simple and effective Long Period Grating chemical sensor for detecting the traces of Cadmium (Cd++ in drinking water at ppm level. Long Period gratings (LPG were fabricated by point-by-point technique with CO2 laser. We have characterized the LPG concentration sensor sensitivity for different solutions of Cd concentrations varying from 0.01 ppm to 0.04 ppm by injecting white Light source and observed transmitted spectra using Optical Spectrum Analyzer (OSA. Proper reagents have been used in the solutions for detection of the Cd species. The overall shift in wavelength is 10 nm when surrounding medium gradually changed from water to 0.04 ppm of cadmium concentrations. A comparative study has been done using sophisticated spectroscopic atomic absorption spectrometer (AAS and Inductively Coupled Plasma (ICP instruments. The spectral sensitivity enhancement was done by modifying grating surface with gold nanoparticles.

  14. Dynamics of Coulomb correlations in semiconductors in high magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Fromer, Neil Alan [Univ. of California, Berkeley, CA (United States)

    2002-01-01

    Current theories have been successful in explaining many nonlinear optical experiments in undoped semiconductors. However, these theories require a ground state which is assumed to be uncorrelated. Strongly correlated systems of current interest, such as a two dimensional electron gas in a high magnetic field, cannot be explained in this manner because the correlations in the ground state and the low energy collective excitations cause a breakdown of the conventional techniques. We perform ultrafast time-resolved four-wave mixing on $n$-modulation doped quantum wells, which contain a quasi-two dimensional electron gas, in a large magnetic field, when only a single Landau level is excited and also when two levels are excited together. We find evidence for memory effects and as strong coupling between the Landau levels induced by the electron gas. We compare our results with simulations based on a new microscopic approach capable of treating the collective effects and correlations of the doped electrons, and find a good qualitative agreement. By looking at the individual contributions to the model, we determine that the unusual correlation effects seen in the experiments are caused by the scattering of photo-excited electron-hole pairs with the electron gas, leading to new excited states which are not present in undoped semiconductors, and also by exciton-exciton interactions mediated by the long-lived collective excitations of the electron gas, inter-Landau level magnetoplasmons.

  15. Self propagating high temperature synthesis of ferrites in magnetic fields

    CERN Document Server

    Affleck, L

    2002-01-01

    Self propagating high temperature synthesis (SHS) reactions have been performed on mixtures of BaO sub 2 , Fe and Fe sub 2 O sub 3 to form barium ferrite, BaFe sub 1 sub 2 O sub 1 sub 9. Reactions were conducted in zero field and in an applied magnetic field of 1.1 T with the aim of exploring the influence of the field. The temperature and velocity of the reactions were measured and the products, both post-SHS and post-annealing, were characterised by techniques including X-ray diffraction, Moessbauer spectroscopy, vibrating sample magnetometry and electron microprobe analysis. The applied magnetic field was found to lead to hotter and faster reactions, a greater degree of conversion of the reactants, a needle-like microstructure in the post-SHS product, and a reduced coercive field (approx 20-30 %) in the annealed product, compared to zero field. Sodium perchlorate was used as an internal oxidising agent, and found to produce similar effects. Correlations were observed between the temperature reached in the ...

  16. The strain-rate sensitivity of high-strength high-toughness steels.

    Energy Technology Data Exchange (ETDEWEB)

    Dilmore, M.F. (AFRL/MNMW, Eglin AFB, FL); Crenshaw, Thomas B.; Boyce, Brad Lee

    2006-01-01

    The present study examines the strain-rate sensitivity of four high strength, high-toughness alloys at strain rates ranging from 0.0002 s-1 to 200 s-1: Aermet 100, a modified 4340, modified HP9-4-20, and a recently developed Eglin AFB steel alloy, ES-1c. A refined dynamic servohydraulic method was used to perform tensile tests over this entire range. Each of these alloys exhibit only modest strain-rate sensitivity. Specifically, the strain-rate sensitivity exponent m, is found to be in the range of 0.004-0.007 depending on the alloy. This corresponds to a {approx}10% increase in the yield strength over the 7-orders of magnitude change in strain-rate. Interestingly, while three of the alloys showed a concominant {approx}3-10% drop in their ductility with increasing strain-rate, the ES1-c alloy actually exhibited a 25% increase in ductility with increasing strain-rate. Fractography suggests the possibility that at higher strain-rates ES-1c evolves towards a more ductile dimple fracture mode associated with microvoid coalescence.

  17. A High-Sensitivity Current Sensor Utilizing CrNi Wire and Microfiber Coils

    Directory of Open Access Journals (Sweden)

    Xiaodong Xie

    2014-05-01

    Full Text Available We obtain an extremely high current sensitivity by wrapping a section of microfiber on a thin-diameter chromium-nickel wire. Our detected current sensitivity is as high as 220.65 nm/A2 for a structure length of only 35 μm. Such sensitivity is two orders of magnitude higher than the counterparts reported in the literature. Analysis shows that a higher resistivity or/and a thinner diameter of the metal wire may produce higher sensitivity. The effects of varying the structure parameters on sensitivity are discussed. The presented structure has potential for low-current sensing or highly electrically-tunable filtering applications.

  18. Highly Sensitive Sensors Based on Photonic Crystal Fiber Modal Interferometers

    Directory of Open Access Journals (Sweden)

    Joel Villatoro

    2009-01-01

    Full Text Available We review the research on photonic crystal fiber modal interferometers with emphasis placed on the characteristics that make them attractive for different sensing applications. The fabrication of such interferometers is carried out with different post-processing techniques such as grating inscription, tapering or cleaving, and splicing. In general photonic crystal fiber interferometers exhibit low thermal sensitivity while their applications range from sensing strain or temperature to refractive index and volatile organic compounds.

  19. Improvement in the light sensitivity of the ultrahigh-speed high-sensitivity CCD with a microlens array

    Science.gov (United States)

    Hayashida, T.,; Yonai, J.; Kitamura, K.; Arai, T.; Kurita, T.; Tanioka, K.; Maruyama, H.; Etoh, T. Goji; Kitagawa, S.; Hatade, K.; Yamaguchi, T.; Takeuchi, H.; Iida, K.

    2008-02-01

    We are advancing the development of ultrahigh-speed, high-sensitivity CCDs for broadcast use that are capable of capturing smooth slow-motion videos in vivid colors even where lighting is limited, such as at professional baseball games played at night. We have already developed a 300,000 pixel, ultrahigh-speed CCD, and a single CCD color camera that has been used for sports broadcasts and science programs using this CCD. However, there are cases where even higher sensitivity is required, such as when using a telephoto lens during a baseball broadcast or a high-magnification microscope during science programs. This paper provides a summary of our experimental development aimed at further increasing the sensitivity of CCDs using the light-collecting effects of a microlens array.

  20. Desorption of harmful hydrocarbon compounds in soil using micron-sized magnetic particles and high-frequency magnetic fields

    Directory of Open Access Journals (Sweden)

    Bailey S. Tye

    2017-10-01

    Full Text Available This research looks at the use of high frequency (HF magnetic fields to desorb/reduce harmful chemical compounds within gasoline and diesel that commonly leak out of underground storage tanks. Using a multi-strand coil design, measured magnetic fields of over 3 kilo-amperes per meter are generated at an optimal frequency of 117 kHz without skin-depth losses, and without the use of expensive super-conductors or liquid-cooled mechanisms. This high frequency magnetic field is successfully used in non-contact-based magnetic heating and desorption of Gasoline and Diesel mixed with sand, water and easily-dispersible, benign micrometer-sized iron filings, used as a magnetic absorber. Gas chromatography (GC tests done on magnetically-heated Gasoline-soil and Diesel-soil mixtures show desorption/reduction of gasoline and diesel by 44% and 51% respectively, but desorption/reduction of harmful BTEX compounds and other chemical irritants within Gasoline and Diesel by 28–66% after only 80 minutes of magnetic heating. Review of remediation/desorption methods show magnetic fields fare favorably in comparison to other methods that require longer treatment period or the use of secondary pollutants at reducing hydrocarbon and BTEX compounds in them. Keywords: Engineering, Applied sciences, Environmental science, Electrical engineering

  1. High-sensitivity damage detection based on enhanced nonlinear dynamics

    Science.gov (United States)

    Epureanu, Bogdan I.; Yin, Shih-Hsun; Derriso, Mark M.

    2005-04-01

    One of the most important aspects of detecting damage in the framework of structural health monitoring is increasing the sensitivity of the monitored feature to the presence, location, and extent of damage. Distinct from previous techniques of obtaining information about the monitored structure—such as measuring frequency response functions—the approach proposed herein is based on an active interrogation of the system. This interrogation approach allows for the embedding of the monitored system within a larger system by means of a nonlinear feedback excitation. The dynamics of the larger system is then analyzed in state space, and the shape of the attractor of its dynamics is used as a complex geometric feature which is very sensitive to damage. The proposed approach is implemented for monitoring the structural integrity of a panel forced by transverse loads and undergoing limit cycle oscillations and chaos. The nonlinear von Karman plate theory is used to obtain a model for the panel combined with a nonlinear feedback excitation. The presence of damage is modeled as loss of stiffness of various levels in a portion of the plate at various locations. The sensitivity of the proposed approach to parametric changes is shown to be an effective tool in detecting damages. An earlier version was presented at the SPIE 11th International Symposium on Smart Structures and Materials.

  2. Economical Alternatives for High Sensitivity in Atomic Spectrometry Laboratory

    Directory of Open Access Journals (Sweden)

    O. Yavuz Ataman

    2007-12-01

    Full Text Available The most commonly used analytical tools for determination of elements at trace levels are atomic absorption spectrometry (AAS, inductively coupled plasma, optical emission and mass spectrometry (ICP-OES and ICP-MS and atomic fluorescence spectrometry (AFS. Although sensitive plasma techniques are becoming predominant in most of the western laboratories, AAS keeps its importance in developing countries. Simple and inexpensive ways of enhancing sensitivity will be described for laboratories equipped with only a flame AA spectrometer. Although there are many chemical preconcentration procedures to improve sensitivity of flame AAS, only some atom trapping techniques will be included here. One kind of atom trapping device is a slotted quartz tube (SQT used for in situ preconcentration of analyte species followed by a rapid revolatilization cycle to obtain an enhanced signal. These devices provide limits of detection at a level of µg L-1. Another kind of atom trapping involves use of vapor generation technique and quartz or tungsten atom trapping surfaces. The analytical steps consist of the generation of volatile species, usually by hydride formation using NaBH4, trapping these species at the surface of an atom trap held at an optimized temperature and finally re-volatilizing analyte species by rapid heating of trap. These species are transported using a carrier gas to an externally heated quartz tube as commonly used in hydride generation AAS systems; a transient signal is formed and measured. These traps have limits of detection in the order of ng L-1.

  3. Magnetic anisotropy study of UGe{sub 2}in a static high magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Sakon, T [Center for Geo-Enviromental Science, Akita University, Akita City, 010-8502 (Japan); Saito, S [Center for Geo-Enviromental Science, Akita University, Akita City, 010-8502 (Japan); Koyama, K [Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai, 980-8577 (Japan); Awaji, S [Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai, 980-8577 (Japan); Sato, I [Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai, 980-8577 (Japan); Nojima, T [Center for Low Temperature Science, Tohoku University, Katahira 2-1-1, Sendai, 980-8577 (Japan); Watanabe, K [Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai, 980-8577 (Japan); Motokawa, M [Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai, 980-8577 (Japan); Sato, N K [Department of Physics, Graduated School of Science, Nagoya University, Nagoya 464-8602 (Japan)

    2006-11-15

    UGe{sub 2} has orthorhombic C{sub mmm} crystalline symmetry and shows ferromagnetic Heavy-Fermion (HF) Superconductor, which provides superconductivity under pressure in the range from 1.0 GPa to 1.5 GPa. Magnetic field dependence of magnetization shows strong magnetic anisotropy. When a magnetic field is applied parallel to easy axis (a-axis), magnetization presents ferromagnetic behavior. At 4.2 K, which is much lower than the Curie temperature T{sub c} = 54 K. Spontaneous magnetization is 1.4 {mu}{sub B}/U, and the magnetization gradually increase with increasing field. On the contrary, when a field is applied parallel to hard axis (b-axis or c-axis), magnetization increases linearly with increasing magnetic field. As for H//b-axis, magnetization is 0.23 {mu} {sub B}/U even at 27 T. Magnetocrystalline anisotropy constant is obtained as 230 [T {mu}{sub B}] 3.4[kJ/kg] at 4.2 K. This value is comparable with rare-earth magnet Nd{sub 2}Fe{sub 17}, which is typical strongly correlated ferromagnet.

  4. Reversible effect of magnetic fields on human lymphocyte activation patterns: different sensitivity of naive and memory lymphocyte subsets.

    Science.gov (United States)

    Salerno, Sergio; La Mendola, Carmela; La Manna, Marco Pio; Lo Casto, Antonio; Caccamo, Nadia; Salerno, Alfredo

    2009-10-01

    The aim of this study was to investigate the influence of 50 Hz magnetic or static magnetic fields of 0.5 mT on subsets of human CD4(+) T cells in terms of cytokine release/content, cell proliferation and intracellular free calcium concentration. CD4(+) T cells can be divided into different subsets on the basis of surface marker expression, such as CD45, and T cells can be divided into naive (CD45RA(+)) and memory (CD45RA(-)) cells. In this study, the effects of magnetic fields after 24 and 48 h of cell culture were analyzed. We found that the CD4(+)CD45RA(-) T subset were more sensitive after 2 h of exposure. Decreases in the release/content of IFN-gamma, in cell proliferation and in intracellular free calcium concentrations were observed in exposed CD4(+)CD45RA(-) T cells compared to CD4(+)CD45RA(+) T cells. The results suggest that exposure to the magnetic fields induces a delay in the response to stimulants and that modifications are rapidly reversible, at least after a short exposure.

  5. Development and qualification of a high sensitivity, high throughput Q-PCR assay for quantitation of residual host cell DNA in purification process intermediate and drug substance samples.

    Science.gov (United States)

    Zhang, Wei; Wu, Meng; Menesale, Emily; Lu, Tongjun; Magliola, Aeona; Bergelson, Svetlana

    2014-11-01

    Methods of high sensitivity, accuracy and throughput are needed for quantitation of low level residual host cell DNA in purification process intermediates and drug substances of therapeutic proteins. In this study, we designed primer/probe sets targeting repetitive Alu repeats or Alu-equivalent sequences in the human, Chinese hamster and murine genomes. When used in quantitative polymerase chain reactions (Q-PCRs), these primer/probe sets showed high species specificity and gave significantly higher sensitivity compared to those targeting the low copy number GAPDH gene. This allowed for detection of residual host cell DNA of much lower concentrations and, for some samples, eliminated the need for DNA extraction. By combining the high sensitivity Alu Q-PCR with high throughput automated DNA extraction using an automated MagMAX magnetic particle processor, we successfully developed and qualified a highly accurate, specific, sensitive and efficient method for the quantitation of residual host cell DNA in process intermediates and drug substances of multiple therapeutic proteins purified from cells of multiple species. Compared to the previous method using manual DNA extraction and primer/probe sets targeting the GAPDH gene, this new method increased our DNA extraction throughput by over sevenfold, and lowered the lower limit of quantitation by up to eightfold. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. High-performance and high-sensitivity applications of graphene transistors with self-assembled monolayers.

    Science.gov (United States)

    Yeh, Chao-Hui; Kumar, Vinod; Moyano, David Ricardo; Wen, Shao-Hsuan; Parashar, Vyom; Hsiao, She-Hsin; Srivastava, Anchal; Saxena, Preeti S; Huang, Kun-Ping; Chang, Chien-Chung; Chiu, Po-Wen

    2016-03-15

    Charge impurities and polar molecules on the surface of dielectric substrates has long been a critical obstacle to using graphene for its niche applications that involve graphene's high mobility and high sensitivity nature. Self-assembled monolayers (SAMs) have been found to effectively reduce the impact of long-range scatterings induced by the external charges. Yet, demonstrations of scalable device applications using the SAMs technique remains missing due to the difficulties in the device fabrication arising from the strong surface tension of the modified dielectric environment. Here, we use patterned SAM arrays to build graphene electronic devices with transport channels confined on the modified areas. For high-mobility applications, both rigid and flexible radio-frequency graphene field-effect transistors (G-FETs) were demonstrated, with extrinsic cutoff frequency and maximum oscillation frequency enhanced by a factor of ~2 on SiO2/Si substrates. For high sensitivity applications, G-FETs were functionalized by monoclonal antibodies specific to cancer biomarker chondroitin sulfate proteoglycan 4, enabling its detection at a concentration of 0.01 fM, five orders of magnitude lower than that detectable by a conventional colorimetric assay. These devices can be very useful in the early diagnosis and monitoring of a malignant disease. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. High mass resolution time of flight mass spectrometer for measuring products in heterogeneous catalysis in highly sensitive microreactors

    DEFF Research Database (Denmark)

    Andersen, Thomas; Jensen, Robert; Christensen, M. K.

    2012-01-01

    We demonstrate a combined microreactor and time of flight system for testing and characterization of heterogeneous catalysts with high resolution mass spectrometry and high sensitivity. Catalyst testing is performed in silicon-based microreactors which have high sensitivity and fast thermal...

  8. High field magnetic behavior in Boron doped Fe{sub 2}VAl Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Venkatesh, Ch., E-mail: venkyphysicsiitm@gmail.com [Department of Physics, Indian Institute of Technology, Kharagpur (India); DCMP & MS, Tata Institute of Fundamental Research, Mumbai (India); Vasundhara, M., E-mail: vasu.mutta@gmail.com [Materials Science and Technology Division, National Institute for Interdisciplinary Science and Technology, CSIR, Trivandrum 695019 (India); Srinivas, V. [Department of Physics, Indian Institute of Technology, Chennai (India); Rao, V.V. [Cryogenic Engineering Centre, Indian Institute of Technology, Kharagpur (India)

    2016-11-15

    We have investigated the magnetic behavior of Fe{sub 2}VAl{sub 1−x}B{sub x} (x=0, 0.03, 0.06 and 0.1) alloys under high temperature and high magnetic field conditions separately. Although, the low temperature DC magnetization data for the alloys above x>0 show clear magnetic transitions, the zero field cooled (ZFC) and field cooled (FC) curves indicate the presence of spin cluster like features. Further, critical exponent (γ) deduced from the initial susceptibility above the T{sub c}, does not agree with standard models derived for 3 dimensional long range magnetic systems. The deviation in γ values are consistent with the short range magnetic nature of these alloys. We further extend the analysis of magnetic behavior by carrying the magnetization measurements at high temperatures and high magnetic fields distinctly. We mainly emphasize the following observations; (i) The magnetic hysteresis loops show sharp upturns at lower fields even at 900 K for all the alloys. (ii) High temperature inverse susceptibility do not overlap until T=900 K, indicating the persistent short range magnetic correlations even at high temperatures. (iii) The Arrott's plot of magnetization data shows spontaneous moment (M{sub S}) for the x=0 alloy at higher magnetic fields which is absent at lower fields (<50 kOe), while the Boron doped samples show feeble M{sub S} at lower fields. The origin of this short range correlation is due to presence of dilute magnetic heterogeneous phases which are not detected from the X-ray diffraction method. - Highlights: • Short range magnetic character has been confirmed by the critical exponents analysis. • Magnetoresistace is about −14% with non-saturating tendency even at 150 kOe for Fe{sub 2}VAl alloy. • Boron doped Fe{sub 2}VAl alloys show a weak magnetism even at T=900 K.

  9. Electric and magnetic field measurements in a high voltage center.

    Science.gov (United States)

    Safigianni, Anastasia S; Spyridopoulos, Anastasios I; Kanas, Vasilis L

    2012-01-01

    This paper investigates the electric and magnetic fields inside a large high voltage center constituted both of 400/150 and 150/20 kV substation areas. Results of previous field measurements and calculations in substations, made by the authors of this paper or other researchers, are presented first. The basic data distinguishing the examined center from previously examined substations follow. The main results of the field measurements in the areas of the above-mentioned center are presented in relevant diagrams. General conclusions arising from the comparison of the measured field values with relevant reference levels in force for safe public and occupational exposure as well as with the results of previous research are finally given.

  10. Nonlinear Magnetic Phenomena in Highly Polarized Target Materials

    CERN Document Server

    Kiselev, Yu F

    2007-01-01

    The report introduces and surveys nonlinear magnetic phenomena which have been observed at high nuclear polarizations in polarized targets of the SMC and of the COMPASS collaborations at CERN. Some of these phenomena, namely the frequency modulation eect and the distortion of the NMR line shape, promote the development of the polarized target technique. Others, as the spin-spin cross-relaxation between spin subsystems can be used for the development of quantum statistical physics. New findings bear on an electromagnetic noise and the spectrally resolved radiation from LiD with negatively polarized nuclei detected by low temperature bolometers. These nonlinear phenomena need to be taken into account for achieving the ultimate polarizations.

  11. Preparation of a magnetic-field-sensitive hydrogel and preliminary study of its drug release behavior.

    Science.gov (United States)

    Namdeo, Mini; Bajpai, S K; Kakkar, S

    2009-01-01

    The study describes the in situ formation of magnetite nanoparticles within a swollen polyacrylamide hydrogel. The average diameter of nanoparticles, as determined by TEM analysis, was found to be nearly 12.5 nm. In XRD analysis the characteristic peaks, observed at d = 3.07, 2.78, 2.64, 2.53, 2.32 and 2.03, also confirmed the formation of magnetite within the polymer network. The percent swelling of magnetite-loaded gel in physiological fluid was observed to decrease with increasing amount of magnetite in the gel. Moreover, the percent swelling increased from 140 to 254% as the strength of the applied magnetic field increased from 500 to 2500 Oe. Finally, the model drug, vitamin B(2), loaded magnetic gels showed relatively slower release in the presence of an applied magnetic field.

  12. The radial diffusivity and magnetization transfer pool size ratio are sensitive markers for demyelination in a rat model of type III multiple sclerosis (MS) lesions

    OpenAIRE

    Janve, Vaibhav A.; Zu, Zhongliang; Yao, Song-Yi; Li, Ke; Zhang, Fang Lin; Wilson, Kevin; Ou, Xiawei; Does, Mark D.; Subramaniam, Sriram; Gochberg, Daniel F

    2013-01-01

    Determining biophysical sensitivity and specificity of quantitative magnetic resonance imaging is essential to develop effective imaging metrics of neurodegeneration. Among these metrics apparent pool size ratio (PSR) from quantitative magnetization transfer (qMT) imaging and radial diffusivity (RD) from diffusion tensor imaging (DTI) are both known to relate to histological measure of myelin density and integrity. However their relative sensitivities towards quantitative myelin detection are...

  13. The OMERACT Psoriatic Arthritis Magnetic Resonance Imaging Score (PsAMRIS) is reliable and sensitive to change: results from an OMERACT workshop

    DEFF Research Database (Denmark)

    Bøyesen, Pernille; McQueen, Fiona M; Gandjbakhch, Frédérique

    2011-01-01

    The aim of this multireader exercise was to assess the reliability and sensitivity to change of the psoriatic arthritis magnetic resonance imaging score (PsAMRIS) in PsA patients followed for 1 year.......The aim of this multireader exercise was to assess the reliability and sensitivity to change of the psoriatic arthritis magnetic resonance imaging score (PsAMRIS) in PsA patients followed for 1 year....

  14. Temperature-sensitive polymer-coated magnetic nanoparticles as a potential drug delivery system for targeted therapy of thyroid cancer.

    Science.gov (United States)

    Koppolu, Bhanuprasanth; Bhavsar, Zarna; Wadajkar, Aniket S; Nattama, Sivaniarvindpriya; Rahimi, Maham; Nwariaku, Fiemu; Nguyen, Kytai T

    2012-12-01

    The objective of this work was to develop and investigate temperature-sensitive poly(N-isopropylacrylamide-acrylamide-allylamine)-coated iron oxide magnetic nanoparticles (TPMNPs) as possible targeted drug carriers for treatments of advanced thyroid cancer (ATC). These nanoparticles were prepared by free radical polymerization of monomers on the surface of silane-coupled iron oxide nanoparticles. In vitro studies demonstrated that TPMNPs were cytocompatible and effectively taken up by cancer cells in a dose-dependent manner. An external magnetic field significantly increased nanoparticle uptake, especially when cells were exposed to physiological flow conditions. Drug loading and release studies using doxorubicin confirmed the temperature-responsive release of drugs from nanoparticles. In addition, doxorubicin-loaded nanoparticles significantly killed ATC cells when compared to free doxorubicin. The in vitro results indicate that TPMNPs have potential as targeted and controlled drug carriers for thyroid cancer treatment.

  15. Electric-field assisted switching of magnetization in perpendicularly magnetized (Ga,Mn)As films at high temperatures

    Science.gov (United States)

    Wang, Hailong; Ma, Jialin; Yu, Xueze; Yu, Zhifeng; Zhao, Jianhua

    2017-01-01

    The electric-field effects on the magnetism in perpendicularly magnetized (Ga,Mn)As films at high temperatures have been investigated. An electric-field as high as 0.6 V nm-1 is applied by utilizing a solid-state dielectric Al2O3 film as a gate insulator. The coercive field, saturation magnetization and magnetic anisotropy have been clearly changed by the gate electric-field, which are detected via the anomalous Hall effect. In terms of the Curie temperature, a variation of about 3 K is observed as determined by the temperature derivative of the sheet resistance. In addition, electrical switching of the magnetization assisted by a fixed external magnetic field at 120 K is demonstrated, employing the gate-controlled coercive field. The above experimental results have been attributed to the gate voltage modulation of the hole density in (Ga,Mn)As films, since the ferromagnetism in (Ga,Mn)As is carrier-mediated. The limited modulation magnitude of magnetism is found to result from the strong charge screening effect introduced by the high hole concentration up to 1.10  ×  1021 cm-3, while the variation of the hole density is only about 1.16  ×  1020 cm-3.

  16. Highly sensitive measurement of submicron waveguides based on Brillouin scattering

    Science.gov (United States)

    Godet, Adrien; Ndao, Abdoulaye; Sylvestre, Thibaut; Beugnot, Jean-Charles; Phan Huy, Kien

    2017-02-01

    Fabrication and characterization of submicron optical waveguides is one of the major challenges in modern photonics, as they find many applications from optical sensors to plasmonic devices. Here we report on a novel technique that allows for a complete and precise characterization of silica optical nanofibers. Our method relies on the Brillouin backscattering spectrum analysis that directly depends on the waveguide geometry. Our method was applied to several fiber tapers with diameter ranging from 500 nm to 3 μm. Results were compared to scanning electron microscopy (SEM) images and numerical simulations with very good agreement and similar sensitivity.

  17. Extremely high frequency sensitivity in a ‘simple’ ear

    OpenAIRE

    Moir, Hannah M.; Jackson, Joseph C.; Windmill, James F. C.

    2013-01-01

    An evolutionary war is being played out between the bat, which uses ultrasonic calls to locate insect prey, and the moth, which uses microscale ears to listen for the approaching bat. While the highest known frequency of bat echolocation calls is 212 kHz, the upper limit of moth hearing is considered much lower. Here, we show that the greater wax moth, Galleria mellonella, is capable of hearing ultrasonic frequencies approaching 300 kHz; the highest frequency sensitivity of any animal. With a...

  18. High-density all-optical magnetic recording using a high-NA lens illuminated by circularly polarized pulse lights

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yaoju [College of Physics and Electronic Information, Wenzhou University, Wenzhou 325035 (China)], E-mail: zhangyaoju@sohu.com; Bai Jianping [School of Physics and Electronic Engineering, Nanyang Normal College, Nanyang 472000 (China)

    2008-10-06

    We propose a method for high-density all-optical magnetic recording. Our analyses, based on the vector diffraction theory, show that owing to the inverse Faraday effect, circularly polarized laser pulses focused by a high numerical aperture (NA) lens can induce a small magnetization domain. For an example, the FWHM of the effective magnetization domain is 0.4646{lambda} when NA=0.85. The magnetization direction is basically perpendicular to the surface of the optic-magneto film within the effective magnetization domain and the switching direction of magnetization can be controlled by the helicity of the incident circularly polarized light. These characteristics are useful to next-generation high-density all-optical magnetic storage.

  19. The Relationship between Ethical Sensitivity, High Ability and Gender in Higher Education Students

    Science.gov (United States)

    Schutte, Ingrid; Wolfensberger, Marca; Tirri, Kirsi

    2014-01-01

    This study examined the ethical sensitivity of high-ability undergraduate students (n=731) in the Netherlands who completed the 28-item Ethical Sensitivity Scale Questionnaire (ESSQ) developed by Tirri & Nokelainen (2007; 2011). The ESSQ is based on Narvaez' (2001) operationalization of ethical sensitivity in seven dimensions. The following…

  20. Analysis of Cyberbullying Sensitivity Levels of High School Students and Their Perceived Social Support Levels

    Science.gov (United States)

    Akturk, Ahmet Oguz

    2015-01-01

    Purpose: The purpose of this paper is to determine the cyberbullying sensitivity levels of high school students and their perceived social supports levels, and analyze the variables that predict cyberbullying sensitivity. In addition, whether cyberbullying sensitivity levels and social support levels differed according to gender was also…

  1. Numerical study of magnetic nanoparticles concentration in biofluid (blood) under influence of high gradient magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Reza Habibi, Mohammad, E-mail: mohammad_habibi_4@yahoo.co [Mechanical Engineering Department, K.N.Toosi University of Technology, P.O. Box 19395-1999, Tehran (Iran, Islamic Republic of); Ghasemi, Majid [Mechanical Engineering Department, K.N.Toosi University of Technology, P.O. Box 19395-1999, Tehran (Iran, Islamic Republic of)

    2011-01-15

    Ferrofluids are widely used in pharmaceutical industries as magnetic separation tools, anti-cancer drug carriers and micro-valve applications. The purpose of the current study is to investigate the effect of a magnetic field on the volume concentration of magnetic nanoparticles of a non-Newtonian biofluid (blood) as a drug carrier. The effect of particles on the flow field is considered. The governing non-linear differential equations, concentration and Naviar-stokes are coupled with the magnetic field. To solve these equations, a finite volume based code is developed and utilized. The results show accumulation of magnetic nanoparticles near the magnetic source until it looks like a solid object. The accumulation of nanoparticles is due to the magnetic force that overcomes the fluid drag force. As the magnetic strength and size of the magnetic particles increase, the accumulation of nanoparticles increases, as well. The magnetic susceptibility of particles also affects the flow field and the contour of the concentration considerably.

  2. The smallest detectable difference and sensitivity to change of magnetic resonance imaging and radiographic scoring of structural joint damage in rheumatoid arthritis finger, wrist, and toe joints: a comparison of the OMERACT rheumatoid arthritis magnetic resonance imaging score applied

    DEFF Research Database (Denmark)

    Ejbjerg, Bo Jannik; Vestergaard, Aage; Jacobsen, Søren

    2005-01-01

    To compare 2 magnetic resonance imaging (MRI) approaches and radiographic evaluation according to the Sharp/van der Heijde method with respect to sensitivity to change in joint destruction in patients with rheumatoid arthritis (RA).......To compare 2 magnetic resonance imaging (MRI) approaches and radiographic evaluation according to the Sharp/van der Heijde method with respect to sensitivity to change in joint destruction in patients with rheumatoid arthritis (RA)....

  3. Highly sensitive, self-powered and wearable electronic skin based on pressure-sensitive nanofiber woven fabric sensor.

    Science.gov (United States)

    Zhou, Yuman; He, Jianxin; Wang, Hongbo; Qi, Kun; Nan, Nan; You, Xiaolu; Shao, Weili; Wang, Lidan; Ding, Bin; Cui, Shizhong

    2017-10-11

    The wearable electronic skin with high sensitivity and self-power has shown increasing prospects for applications such as human health monitoring, robotic skin, and intelligent electronic products. In this work, we introduced and demonstrated a design of highly sensitive, self-powered, and wearable electronic skin based on a pressure-sensitive nanofiber woven fabric sensor fabricated by weaving PVDF electrospun yarns of nanofibers coated with PEDOT. Particularly, the nanofiber woven fabric sensor with multi-leveled hierarchical structure, which significantly induced the change in contact area under ultra-low load, showed combined superiority of high sensitivity (18.376 kPa-1, at ~100 Pa), wide pressure range (0.002-10 kPa), fast response time (15 ms) and better durability (7500 cycles). More importantly, an open-circuit voltage signal of the PPNWF pressure sensor was obtained through applying periodic pressure of 10 kPa, and the output open-circuit voltage exhibited a distinct switching behavior to the applied pressure, indicating the wearable nanofiber woven fabric sensor could be self-powered under an applied pressure. Furthermore, we demonstrated the potential application of this wearable nanofiber woven fabric sensor in electronic skin for health monitoring, human motion detection, and muscle tremor detection.

  4. High-gradient magnetic separation using ferromagnetic membrane

    Energy Technology Data Exchange (ETDEWEB)

    Podoynitsyn, Sergey N., E-mail: spod@sky.chph.ras.ru; Sorokina, Olga N., E-mail: alsiona@gmail.com; Kovarski, Alexander L., E-mail: alkogon383@yandex.ru

    2016-01-01

    The magnetic separator with the membrane separating unit made of laser-perforated thick ferromagnetic foil was tested using composite water suspension of magnetic nanoparticles adsorbed on hydroxylapatite microparticles. The average sizes of the particles in the suspension and the magnetic moment of the suspension were measured by dynamic light scattering and electron magnetic resonance correspondingly to evaluate the efficiency of the separation. It was shown experimentally that the separation is effected by the membrane type and the flow rate. Magnetic coarse grains (larger than 1 μm) were captured by the membrane preferably and the magnetic moment of the suspension decreased by 20–25% after the separation. The magnetic field simulation and experimental results demonstrate the higher separation efficiency for thicker membranes. - Highlights: • A new design of magnetic separator with ferromagnetic membrane was developed. • Coarse magnetic particles 1 μm in size are captured by the membrane preferably. • Selectivity of magnetic separation improves with flow rate decrease. • Separation efficiency of thick ferromagnetic membrane is higher than of the thin one.

  5. Rational synthesis of zerovalent iron/bamboo charcoal composites with high saturation magnetization

    Science.gov (United States)

    Mingshan Wu; Jianfeng Ma; Zhiyong Cai; Genlin Tian; Shumin Yang; Youhong Wang; Xing' e Liu

    2015-01-01

    The synthesis of magnetic biochar composites is a major new research area in advanced materials sciences. A series of magnetic bamboo charcoal composites (MBC800, MBC1000 and MBC1200) with high saturation magnetization (Ms) was fabricated in this work by mixing bamboo charcoal powder with an aqueous ferric chloride solution and subsequently...

  6. High resolution three-dimensional magnetization mapping in Tokachidake Volcano using low altitude airborne magnetic survey data

    Science.gov (United States)

    Iwata, M.; Mogi, T.; Okuma, S.; Nakatsuka, T.

    2016-12-01

    Tokachidake Volcano, central Hokkaido, Japan erupted in 1926, 1962 and 1988-1989 in the 20th century from the central part. In recent years, expansions of the edifice of the volcano at shallow depth and increases of the volcanic smoke in the Taisho crater were observed (Meteorological Agency of Japan, 2014). Magnetic changes were observed at the 62-2 crater by repeated magnetic measurements in 2008-2009, implying a demagnetization beneath the crater (Hashimoto at al., 2010). Moreover, a very low resistivity part was found right under the 62-2 crater from an AMT survey (Yamaya et al., 2010). However, since the station numbers of the survey are limited, the area coverage is not sufficient. In this study, we have re-analyzed high-resolution aeromagnetic data to delineate the three-dimensional magnetic structure of the volcano to understand the nature of other craters.A low altitude airborne magnetic survey was conducted in 2014 mainly over the active areas of the volcano by the Ministry of Land, Infrastructure, Transport and Tourism to manage land slide risk in the volcano. The survey was flown at an altitude of 60 m above ground by a helicopter with a Cesium magnetometer in the towed-bird 30m below the helicopter. The low altitude survey enables us to delineate the detailed magnetic structure. We calculated magnetic anomaly distribution on a smooth surface assuming equivalent anomalies below the observation surface. Then the 3D magnetic imaging method (Nakatsuka and Okuma, 2014) was applied to the magnetic anomalies to reveal the three-dimensional magnetic structure.As a result, magnetization highs were seen beneath the Ground crater, Suribachi crater and Kitamuki crater. This implies that magmatic activity occurred in the past at these craters. These magma should have already solidified and acquired strong remanent magnetization. Relative magnetization lows were seen beneath the 62-2 crater and the Taisho crater where fumarolic activity is active. However a

  7. Conceptual design of a compact high gradient quadrupole magnet of varying strength using permanent magnets

    Directory of Open Access Journals (Sweden)

    Gautam Sinha

    2018-02-01

    Full Text Available A concept is presented to design magnets using cylindrical-shaped permanent-magnet blocks, where various types of magnetic fields can be produced by either rotating or varying the size of the magnetic blocks within a given mechanical structure. A general method is introduced to calculate the 3D magnetic field produced by a set of permanent magnets. An analytical expression of the 2D field and the condition to generate various magnetic fields like dipole, quadrupole, and sextupole are derived. Using the 2D result as a starting point, a computer code is developed to get the optimum orientation of the magnets to obtain the user-specific target field profile over a given volume in 3D. Designs of two quadrupole magnets are presented, one using 12 and the other using 24 permanent-magnet blocks. Variation of the quadrupole strength is achieved using tuning coils of a suitable current density and specially designed end tubes. A new concept is introduced to reduce the integrated quadrupole field strength by inserting two hollow cylindrical tubes made of iron, one at each end. This will not affect the field gradient at the center but reduce the integrated field strength by shielding the magnetic field near the ends where the tubes are inserted. The advantages of this scheme are that it is easy to implement, the magnetic axis will not shift, and it will prevent interference with nearby devices. Around 40% integrated field variation is achieved using this method in the present example. To get a realistic estimation of the field quality, a complete 3D model using a nonlinear B-H curve is also studied using a finite-element-based computer code. An example to generate around an 80  T/m quadrupole field gradient is also presented.

  8. Giant magnetoimpedance intrinsic impedance and voltage sensitivity of rapidly solidified Co{sub 66}Fe{sub 2}Cr{sub 4}Si{sub 13}B{sub 15} amorphous wire for highly sensitive sensors applications

    Energy Technology Data Exchange (ETDEWEB)

    Das, Tarun K.; Mandal, Sushil K. [CSIR - National Metallurgical Laboratory, NDE and Magnetic Materials Group, MST Division, Jamshedpur (India); Banerji, Pallab [Indian Institute of Technology, Kharagpur, Materials Science Centre, Kharagpur (India)

    2016-11-15

    We report a systematic study of the influence of wire length, L, dependence of giant magneto-impedance (GMI) sensitivity of Co{sub 66}Fe{sub 2}Cr{sub 4}Si{sub 13}B{sub 15} soft magnetic amorphous wire of diameter ∝ 100 μm developed by in-water quenching technique. The magnetization behaviour (hysteresis loops) of the wire with different length (L = 1, 2, 3, 5, 8 and 10 cm) has been evaluated by fuxmetric induction method. It was observed that the behaviour of the hysteresis loops change drastically with the wire length, being attributed to the existence of a critical length, L{sub C}, found to be around 3 cm. GMI measurements have been taken using automated GMI measurement system and the GMI sensitivities in terms of intrinsic impedance sensitivity (S{sub Ω/Am}{sup -1}) and voltage sensitivity (S{sub V/Am}{sup -1}) of the wire have been evaluated under optimal bias field and excitation current. It was found that the maximum (S{sub Ω/Am}{sup -1}){sub max} ∼ 0.63 Ω/kAm{sup -1}/cm and (S{sub V/Am}{sup -1}){sub max} ∼ 3.10 V/kAm{sup -1}/cm were achieved at a critical length L{sub C} ∝ 3 cm of the wire for an AC current of 5 mA and a frequency of 5 MHz. These findings provide crucial insights for optimization of the geometrical dimensions of magnetic sensing elements and important practical guidance for designing high sensitive GMI sensors. The relevant combinations of magnetic material parameters and operating conditions that optimize the sensitivity are highlighted. (orig.)

  9. RAPID COMMUNICATION: High performance superconducting wire in high applied magnetic fields via nanoscale defect engineering

    Science.gov (United States)

    Wee, Sung Hun; Goyal, Amit; Zuev, Yuri L.; Cantoni, Claudia

    2008-09-01

    High temperature superconducting (HTS) wires capable of carrying large critical currents with low dissipation levels in high applied magnetic fields are needed for a wide range of applications. In particular, for electric power applications involving rotating machinery, such as large-scale motors and generators, a high critical current, Ic, and a high engineering critical current density, JE, in applied magnetic fields in the range of 3-5 Tesla (T) at 65 K are required. In addition, exceeding the minimum performance requirements needed for these applications results in a lower fabrication cost, which is regarded as crucial to realize or enable many large-scale bulk applications of HTS materials. Here we report the fabrication of short segments of a potential superconducting wire comprised of a 4 µm thick YBa2Cu3O7-δ (YBCO) layer on a biaxially textured substrate with a 50% higher Ic and JE than the highest values reported previously. The YBCO film contained columns of self-assembled nanodots of BaZrO3 (BZO) roughly oriented along the c-axis of YBCO. Although the YBCO film was grown at a high deposition rate, three-dimensional self-assembly of the insulating BZO nanodots still occurred. For all magnetic field orientations, minimum Ic and JE at 65 K, 3 T for the wire were 353 A cm-1 and 65.4 kA cm-2, respectively.

  10. A new compact, high sensitivity neutron imaging system

    Energy Technology Data Exchange (ETDEWEB)

    Caillaud, T.; Landoas, O.; Briat, M.; Rosse, B.; Thfoin, I.; Philippe, F.; Casner, A.; Bourgade, J. L.; Disdier, L. [CEA, DAM, DIF,F-91297 Arpajon (France); Glebov, V. Yu.; Marshall, F. J.; Sangster, T. C. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Park, H. S.; Robey, H. F.; Amendt, P. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    2012-10-15

    We have developed a new small neutron imaging system (SNIS) diagnostic for the OMEGA laser facility. The SNIS uses a penumbral coded aperture and has been designed to record images from low yield (10{sup 9}-10{sup 10} neutrons) implosions such as those using deuterium as the fuel. This camera was tested at OMEGA in 2009 on a rugby hohlraum energetics experiment where it recorded an image at a yield of 1.4 Multiplication-Sign 10{sup 10}. The resolution of this image was 54 {mu}m and the camera was located only 4 meters from target chamber centre. We recently improved the instrument by adding a cooled CCD camera. The sensitivity of the new camera has been fully characterized using a linear accelerator and a {sup 60}Co {gamma}-ray source. The calibration showed that the signal-to-noise ratio could be improved by using raw binning detection.

  11. Highly sensitive urea sensing with ion-irradiated polymer foils

    Energy Technology Data Exchange (ETDEWEB)

    Fink, Dietmar, E-mail: fink@daad-alumni.de [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, P.O. Box 55-534, 09340 Mexico, D.F. (Mexico); Nuclear Physics Institute, Academy of Sciences of the Czech Republic, 250 68 Rez (Czech Republic); Munoz Hernandez, Gerardo [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, P.O. Box 55-534, 09340 Mexico, D.F. (Mexico); Division de Ciencias Naturales e Ingenieria, Universidad Autonoma Metropolitana-Cuajimalpa, Pedro Antonio de los Santos 84, Col. Sn. Miguel Chapultepec, C.P. 11850, Mexico, D.F. (Mexico); Alfonta, Lital, E-mail: alfontal@bgu.ac.il [Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105 (Israel)

    2012-02-15

    Recently we prepared urea-sensors by attaching urease to the inner walls of etched ion tracks within thin polymer foil. Here, alternative track-based sensor configurations are examined where the enzyme remained in solution. The conductivities of systems consisting of two parallel irradiated polymer foils and confining different urea/urease mixtures in between were examined. The correlations between conductivity and urea concentration differed strongly for foils with unetched and etched tracks, which points at different sensing mechanisms - tentatively attributed to the adsorption of enzymatic reaction products on the latent track entrances and to the enhanced conductivity of reaction product-filled etched tracks, respectively. All examined systems enable in principle, urea sensing. They point at the possibility of sensor cascade construction for more sensitive or selective sensor systems.

  12. Large scintillation cells for high sensitivity radon concentration measurements

    Science.gov (United States)

    Cohen, B. L.; El Ganayni, M.; Cohen, E. S.

    1983-07-01

    Methods for improving the sensitivity of scintillation cells for radon concentration measurements were studied with emphasis on improving light collection efficiency. This allows the length and hence the volume of the cell to be increased. Variables studied were choice of scintillator material, its method of application and thickness, length of cell, cell material, type and configuration of reflectors, choice of photomultipliers, and factors affecting background. Response from various areas of the cell surface was studied with an alpha source and with radon filling. Coating the window with phosphor was found to be counter-productive. The optimum results obtained were with the inside of the cell (other than the window) covered with a thick layer of ZnS(Ag), or with a thick layer of reflective material coated with a thin layer of phosphor. With it, a 10 cm diameter plexiglass cell can be extended to at least 50 cm length without difficulty from insufficient pulse height.

  13. Nuclear magnetic resonance studies of half-integer quadrupolar nuclei : sensitivity enhancements using double frequency sweeps

    NARCIS (Netherlands)

    Iuga, Dinu

    2003-01-01

    Exploiting adiabatic passages of the spin transitions, this thesis reports sensitivity enhancements of the MAS and MQMAS experiments on half-integer quadrupolar nuclei. The processes governing frequency sweeping are described. During such experiments the irradiation frequency sweeps through the

  14. Controlling interactions between highly magnetic atoms with Feshbach resonances.

    Science.gov (United States)

    Kotochigova, Svetlana

    2014-09-01

    This paper reviews current experimental and theoretical progress in the study of dipolar quantum gases of ground and meta-stable atoms with a large magnetic moment. We emphasize the anisotropic nature of Feshbach resonances due to coupling to fast-rotating resonant molecular states in ultracold s-wave collisions between magnetic atoms in external magnetic fields. The dramatic differences in the distribution of resonances of magnetic (7)S3 chromium and magnetic lanthanide atoms with a submerged 4f shell and non-zero electron angular momentum is analyzed. We focus on dysprosium and erbium as important experimental advances have been recently made to cool and create quantum-degenerate gases for these atoms. Finally, we describe progress in locating resonances in collisions of meta-stable magnetic atoms in electronic P-states with ground-state atoms, where an interplay between collisional anisotropies and spin-orbit coupling exists.

  15. High sensitivity of gold nanoparticles co-doped with Gd2O3 mesoporous silica nanocomposite to nasopharyngeal carcinoma cells

    Science.gov (United States)

    Wang, Hui; Zhang, Songjin; Tian, Xiumei; Liu, Chufeng; Zhang, Lei; Hu, Wenyong; Shao, Yuanzhi; Li, Li

    2016-10-01

    Nanoprobes for combined optical and magnetic resonance imaging have tremendous potential in early cancer diagnosis. Gold nanoparticles (AuNPs) co-doped with Gd2O3 mesoporous silica nanocomposite (Au/Gd@MCM-41) can produce pronounced contrast enhancement for T1 weighted image in magnetic resonance imaging (MRI). Here, we show the remarkably high sensitivity of Au/Gd@MCM-41 to the human poorly differentiated nasopharyngeal carcinoma (NPC) cell line (CNE-2) using fluorescence lifetime imaging (FLIM). The upconversion luminescences from CNE-2 and the normal nasopharyngeal (NP) cells (NP69) after uptake of Au/Gd@MCM-41 show the characteristic of two-photon-induced-radiative recombination of the AuNPs. The presence of the Gd3+ ion induces a much shorter luminescence lifetime in CNE-2 cells. The interaction between AuNPs and Gd3+ ion clearly enhances the optical sensitivity of Au/Gd@MCM-41 to CNE-2. Furthermore, the difference in the autofluorescence between CNE-2 and NP69 cells can be efficiently demonstrated by the emission lifetimes of Au/Gd@MCM-41 through the Forster energy transfers from the endogenous fluorophores to AuNPs. The results suggest that Au/Gd@MCM-41 may impart high optical resolution for the FLIM imaging that differentiates normal and high-grade precancers.

  16. Development of analytical Fourier transform nuclear magnetic resonance spectroscopy for sensitivity enhancement and mixture analyses

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Steven Tung-Kuen.

    1989-01-01

    FT-NMR has been explored with regard to its ability to analyze mixtures. The recycled-flow NMR method, which permits premagnetized nuclei to flow into the detector before acquisition, allows substantial sensitivity enhancement, especially for those nuclei with inefficient relaxation mechanisms. The enhancement factor of flow NMR over static NMR is between 3.5-5 for the slowly relaxing carbon nuclei. Similar enhancements have been observed in 1D spin-echo and 2D J-resolved experiments. A mathematical discussion of the potential enhancement in recycled-flow NMR indicates that this enhancement could be as large as 20. In addition, flow NMR also provides accurate quantitative {sup 13}C data in substantially less time. These dual advantages of recycled-flow NMR have been applied to analyze two mixtures and to determine the MW{sub n} of several polyethylene glycols. An on-line continuous-flow high performance liquid chromatography (HPLC)/{sup 1}H NMR system has been developed on a 400 MHz FT-NMR spectrometer. The detection limit of this system is estimated to be 30 {mu}g, using alanine and caffeine as test samples. For practical HPLC/NMR analyses, a 200 {mu}g quantity of material may be required. The eluent used in reversed-phase (RP)-HPLC, which interfaces with the proton signals of the eluates, is suppressed by the binomial and WATR (Water Attenuation by T{sub 2} Relaxation) pulse methods. RP-HPLC/{sup 1}H NMR is applied to the separation and identification of antimycin A, a class of antibiotics used in fishery management, and its degradation products, antimycin lactones. A method based on the long range J-resolved (LRJR) NMR experiment is developed to analyze mixtures. LRJR is used to select those carbons that are modulated due to the long range {sub 1}H-{sup 13}C coupling to a specific proton(s).

  17. High frequency electromagnetic interference shielding magnetic polymer nanocomposites

    Science.gov (United States)

    He, Qingliang

    Electromagnetic interference is one of the most concerned pollution and problem right now since more and more electronic devices have been extensively utilized in our daily lives. Besides the interference, long time exposure to electromagnetic radiation may also result in severe damage to human body. In order to mitigate the undesirable part of the electromagnetic wave energy and maintain the long term sustainable development of our modern civilized society, new technology development based researches have been made to solve this problem. However, one of the major challenges facing to the electromagnetic interference shielding is the relatively low shielding efficiency and the high cost as well as the complicated shielding material manufacture. From the materials science point of view, the key solutions to these challenges are strongly depended on the breakthrough of the current limit of shielding material design and manufacture (such as hierarchical material design with controllable and predictable arrangement in nanoscale particle configuration via an easy in-situ manner). From the chemical engineering point of view, the upgrading of advanced material shielding performance and the enlarged production scale for shielding materials (for example, configure the effective components in the shielding material in order to lower their usage, eliminate the "rate-limiting" step to enlarge the production scale) are of great importance. In this dissertation, the design and preparation of morphology controlled magnetic nanoparticles and their reinforced polypropylene polymer nanocomposites will be covered first. Then, the functionalities of these polymer nanocomposites will be demonstrated. Based on the innovative materials design and synergistic effect on the performance advancement, the magnetic polypropylene polymer nanocomposites with desired multifunctionalities are designed and produced targeting to the electromagnetic interference shielding application. In addition

  18. Neural correlates of anxiety sensitivity in panic disorder: A functional magnetic resonance imaging study.

    Science.gov (United States)

    Poletti, Sara; Radaelli, Daniele; Cucchi, Michele; Ricci, Liana; Vai, Benedetta; Smeraldi, Enrico; Benedetti, Francesco

    2015-08-30

    Panic disorder has been associated with dysfunctional neuropsychological dimensions, including anxiety sensitivity. Brain-imaging studies of the neural correlates of emotional processing have identified a network of structures that constitute the neural circuitry for emotions. The anterior cingulate cortex (ACC), medial prefrontal cortex (mPFC) and insula, which are part of this network, are also involved in the processing of threat-related stimuli. The aim of the study was to investigate if neural activity in response to emotional stimuli in the cortico-limbic network is associated to anxiety sensitivity in panic disorder. In a sample of 18 outpatients with panic disorder, we studied neural correlates of implicit emotional processing of facial affect expressions with a face-matching paradigm; correlational analyses were performed between brain activations and anxiety sensitivity. The correlational analyses performed showed a positive correlation between anxiety sensitivity and brain activity during emotional processing in regions encompassing the PFC, ACC and insula. Our data seem to confirm that anxiety sensitivity is an important component of panic disorder. Accordingly, the neural underpinnings of anxiety sensitivity could be an interesting focus for treatment and further research. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  19. Simplified Magnetically Shielded Cylinder Using Flexible Magnetic Sheets for High-Tc Superconducting Quantum Interference Device Magnetocardiogram Systems

    Science.gov (United States)

    Suzuki, Daisuke; Yokosawa, Koichi; Miyashita, Tsuyoshi; Kandori, Akihiko; Tsukada, Keiji; Tsukamoto, Akira; Arakawa, Shunsuke

    2001-10-01

    A small and simple magnetic-shielding cylinder using a new high-permeability sheet, developed for magnetic shielding, can reduce the amount of effort expended on taking magnetocardiogram (MCG) measurements. This sheet is made of a nanocrystalline soft-magnetic material (an Fe-Cu-Nb-Si-B alloy) and is flexible and easy to handle. Moreover, magnetostriction of the material is nearly zero, unlike that of the materials used in conventional magnetic shielding. The shielding cylinder is made up of three tubes of various diameters (but having the same length), placed one inside the other. The shielding cylinder is 1.0 m in diameter and 2.0 m long, and it has a shielding factor of about 35 dB at 1 Hz. The shielding cylinder was tested by measuring MCGs using a high-Tc superconducting quantum interference device (SQUID) gradiometer.

  20. Gold nanoparticle-based inductively coupled plasma mass spectrometry amplification and magnetic separation for the sensitive detection of a virus-specific RNA sequence.

    Science.gov (United States)

    Hsu, I-Hsiang; Chen, Wen-Hung; Wu, Tung-Kung; Sun, Yuh-Chang

    2011-04-08

    We have developed a sensitive gold nanoparticle (AuNP)-based inductively coupled plasma mass spectrometry (ICP-MS) amplification and magnetic separation method for the detection of oligonucleotide sequences. The assay relies on (i) the sandwich-type binding of two designed probe sequences that specifically recognize the target oligonucleotide sequences, (ii) magnetic bead separation, and (iii) AuNP-based ICP-MS amplification detection. To enhance the analytical signal and minimize the background signal resulting from nonspecific binding, we performed a series of experiments to evaluate the effects of various parameters (the concentration of the capture probe; the time required for hybridization; the number of washings required to eliminate nonspecific binding) on the oligonucleotide detection. Under the optimized conditions, the detection limit was 80zmol (corresponding to 1.6fM of the target sequence in a sample volume of 50μL). Moreover, it employs a shorter hybridization step and ICP-MS, this procedure is relatively simple and rapid (ca. 1.5h). Based on the analytical results obtained using complementary and mismatched sequences, our method exhibits good performance in distinguishing complementary and random oligonucleotides. Compared with the "gold standard" methodology (plaque assay) for the quantification of dengue virus, our method has the capability to allow early detection of dengue virus in complicated and small-volume samples, with high specificity, good analytical sensitivity, and superior time-effectiveness. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. 3D neuromelanin-sensitive magnetic resonance imaging with semi-automated volume measurement of the substantia nigra pars compacta for diagnosis of Parkinson's disease

    Energy Technology Data Exchange (ETDEWEB)

    Ogisu, Kimihiro; Shirato, Hiroki [Hokkaido University Graduate School of Medicine, Department of Radiology, Hokkaido (Japan); Kudo, Kohsuke; Sasaki, Makoto [Iwate Medical University, Division of Ultrahigh Field MRI, Iwate (Japan); Sakushima, Ken; Yabe, Ichiro; Sasaki, Hidenao [Hokkaido University Hospital, Department of Neurology, Hokkaido (Japan); Terae, Satoshi; Nakanishi, Mitsuhiro [Hokkaido University Hospital, Department of Radiology, Hokkaido (Japan)

    2013-06-15

    Neuromelanin-sensitive MRI has been reported to be used in the diagnosis of Parkinson's disease (PD), which results from loss of dopamine-producing cells in the substantia nigra pars compacta (SNc). In this study, we aimed to apply a 3D turbo field echo (TFE) sequence for neuromelanin-sensitive MRI and to evaluate the diagnostic performance of semi-automated method for measurement of SNc volume in patients with PD. We examined 18 PD patients and 27 healthy volunteers (control subjects). A 3D TFE technique with off-resonance magnetization transfer pulse was used for neuromelanin-sensitive MRI on a 3T scanner. The SNc volume was semi-automatically measured using a region-growing technique at various thresholds (ranging from 1.66 to 2.48), with the signals measured relative to that for the superior cerebellar peduncle. Receiver operating characteristic (ROC) analysis was performed at all thresholds. Intra-rater reproducibility was evaluated by intraclass correlation coefficient (ICC). The average SNc volume in the PD group was significantly smaller than that in the control group at all the thresholds (P < 0.01, student t test). At higher thresholds (>2.0), the area under the curve of ROC (Az) increased (0.88). In addition, we observed balanced sensitivity and specificity (0.83 and 0.85, respectively). At lower thresholds, sensitivity tended to increase but specificity reduced in comparison with that at higher thresholds. ICC was larger than 0.9 when the threshold was over 1.86. Our method can distinguish the PD group from the control group with high sensitivity and specificity, especially for early stage of PD. (orig.)

  2. 3D neuromelanin-sensitive magnetic resonance imaging with semi-automated volume measurement of the substantia nigra pars compacta for diagnosis of Parkinson's disease.

    Science.gov (United States)

    Ogisu, Kimihiro; Kudo, Kohsuke; Sasaki, Makoto; Sakushima, Ken; Yabe, Ichiro; Sasaki, Hidenao; Terae, Satoshi; Nakanishi, Mitsuhiro; Shirato, Hiroki

    2013-06-01

    Neuromelanin-sensitive MRI has been reported to be used in the diagnosis of Parkinson's disease (PD), which results from loss of dopamine-producing cells in the substantia nigra pars compacta (SNc). In this study, we aimed to apply a 3D turbo field echo (TFE) sequence for neuromelanin-sensitive MRI and to evaluate the diagnostic performance of semi-automated method for measurement of SNc volume in patients with PD. We examined 18 PD patients and 27 healthy volunteers (control subjects). A 3D TFE technique with off-resonance magnetization transfer pulse was used for neuromelanin-sensitive MRI on a 3T scanner. The SNc volume was semi-automatically measured using a region-growing technique at various thresholds (ranging from 1.66 to 2.48), with the signals measured relative to that for the superior cerebellar peduncle. Receiver operating characteristic (ROC) analysis was performed at all thresholds. Intra-rater reproducibility was evaluated by intraclass correlation coefficient (ICC). The average SNc volume in the PD group was significantly smaller than that in the control group at all the thresholds (P 2.0), the area under the curve of ROC (Az) increased (0.88). In addition, we observed balanced sensitivity and specificity (0.83 and 0.85, respectively). At lower thresholds, sensitivity tended to increase but specificity reduced in comparison with that at higher thresholds. ICC was larger than 0.9 when the threshold was over 1.86. Our method can distinguish the PD group from the control group with high sensitivity and specificity, especially for early stage of PD.

  3. Development of High-frequency Soft Magnetic Materials for Power Electronics

    Directory of Open Access Journals (Sweden)

    LIU Jun-chang

    2017-05-01

    Full Text Available The new requirements of high-frequency magnetic properties are put forward for electronic components with the rapid development of power electronics industry and the use of new electromagnetic materials. The properties of magnetic core, which is the key unit of electronic components, determine the performance of electronic components directly. Therefore, it's necessary to study the high-frequency soft magnetic materials. In this paper, the development history of four types of soft magnetic materials was reviewed. The advantages and disadvantages of each kind of soft magnetic materials and future development trends were pointed out. The emphases were placed on the popular soft magnetic composite materials in recent years. The tendency is to develop high-frequency soft magnetic composite materials with the particle size controllable, uniform coating layer on the core and a mass production method from laboratory to industrialization.

  4. High sensitivity of northeastern broadleaf forest trees to water availability

    Science.gov (United States)

    Levesque, M.; Pederson, N.; Andreu-Hayles, L.

    2015-12-01

    Temperate deciduous forests of eastern US provide goods and services to millions of people and play a vital role in the terrestrial carbon and hydrological cycles. However, ongoing climate change and increased in CO2 concentration in the atmosphere (ca) are expected to alter growth and gas exchange of trees, and ultimately forest productivity. Still, the magnitude of these effects is unclear. A better comprehension of the species-specific responses to environmental changes will better inform models and managers on the vulnerability and resiliency of these forests. Tree-ring analysis was combined with δ¹³C and δ18O measurements to investigate growth and physiological responses of red oak (Quercus rubra L.) and tulip poplar (Liriodendron tulipifera L.) in northeastern US to changes in water availability and ca for the period 1950-2014. We found very strong correlations between summer climatic water balance (June-August) and isotopic tree-ring series for δ¹³C (r = -0.65 and -0.73), and δ18O (r = -0.59 and -0.70), for red oak and tulip poplar, respectively. In contrast, tree-ring width was less sensitive to summer water availability (r = 0.33-0.39). Prior to the mid 1980s, low water availability resulted in low stomatal conductance, photosynthesis, and growth. Since that period, pluvial conditions occurring in northeastern US have increased stomatal conductance, carbon uptake, and growth of both species. These findings demonstrate that broadleaf trees in this region could be more sensitive to drought than expected. This appears especially true since much of the calibration period looks wet in a multi-centennial perspective. Further, stronger spatial correlations were found between climate data with tree-ring isotopes than with tree-ring width and the geographical area of the observed δ18O-precipitation response (i.e. the area over which correlations are > 0.5) covers most of the northeastern US. Given the good fit between the isotopic time series and water

  5. Design of microchannels for cryostabilization of high temperature superconducting magnets

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Y.S.; Hull, J.R.; Niemann, R.C.

    1993-10-01

    Microchannel cooling using subcooled liquid nitrogen is proposed to cryogenically stabilize high-temperature superconducting magnets. Various design constraints and parameters are identified and summarized. A graphical method is proposed for the design of microchannel systems. This graphical method helps to reduce the amount of work towards achieving optimum design for a specific application because there are a large number of parameters involved in the design of a microchannel system. The proposed graphical method are illustrated by three examples. The results show that a design window may appear for a given application. Any point within this window is an acceptable design. Another advantage of the graphical method is that, by selecting a design point, the design margin against various design contrains can be easily identified. Any two of the design variables can be selected as the independent variables. The choice depends on specific application and, to a certain extent, on individual preference. The three examples revealed that, for high current density applications, the most scattering constraints are the coolant temperature rise and the fin tip temperatures provided that a moderate pressure drop can be tolerated.

  6. Directed magnetic field induced assembly of high magnetic moment cobalt nanowires

    DEFF Research Database (Denmark)

    Srivastava, Akhilesh Kumar; Madhavi, S.; Ramanujan, R.V.

    2010-01-01

    A directed magnetic field induced assembly technique was employed to align two phase (h.c.p. + f.c.c.) cobalt nanoparticles in a mechanically robust long wire morphology. Co nanoparticles with an average size of 4.3 nm and saturation magnetization comparable to bulk cobalt were synthesized by bor...

  7. Storing quantum information in spins and high-sensitivity ESR.

    Science.gov (United States)

    Morton, John J L; Bertet, Patrice

    2018-02-01

    Quantum information, encoded within the states of quantum systems, represents a novel and rich form of information which has inspired new types of computers and communications systems. Many diverse electron spin systems have been studied with a view to storing quantum information, including molecular radicals, point defects and impurities in inorganic systems, and quantum dots in semiconductor devices. In these systems, spin coherence times can exceed seconds, single spins can be addressed through electrical and optical methods, and new spin systems with advantageous properties continue to be identified. Spin ensembles strongly coupled to microwave resonators can, in principle, be used to store the coherent states of single microwave photons, enabling so-called microwave quantum memories. We discuss key requirements in realising such memories, including considerations for superconducting resonators whose frequency can be tuned onto resonance with the spins. Finally, progress towards microwave quantum memories and other developments in the field of superconducting quantum devices are being used to push the limits of sensitivity of inductively-detected electron spin resonance. The state-of-the-art currently stands at around 65 spins per Hz, with prospects to scale down to even fewer spins. Copyright © 2017. Published by Elsevier Inc.

  8. Magnetic nanoparticles coated with maltose-functionalized polyethyleneimine for highly efficient enrichment of N-glycopeptides.

    Science.gov (United States)

    Li, Jinan; Wang, Fangjun; Wan, Hao; Liu, Jing; Liu, Zheyi; Cheng, Kai; Zou, Hanfa

    2015-12-18

    Hydrophilic interaction chromatography (HILIC) adsorbents have drawn increasing attention in recent years due to their high efficiency in N-glycopeptides enrichment. The hydrophilicity and binding capacity of HILIC adsorbents are crucial to the enrichment efficiency and mass spectrometry (MS) detection sensitivity of N-glycopeptides. Herein, magnetic nanoparticles coated with maltose-functionalized polyethyleneimine (Fe3O4-PEI-Maltose MNPs) were prepared by one-pot solvothermal reaction coupled with "click chemistry" and utilized for N-glycopeptides enrichment. Owing to the presence of hydrophilic and branched polyethyleneimine, the amount of immobilized disaccharide units was improved about four times. The N-glycopeptides capturing capacity was about 150mg/g (IgG/MNPs) and the MS detection limitation as low as 0.5fmol for IgG and 85% average enrichment recovery were feasibly achieved by using this hybrid magnetic adsorbent. Finally, 1237 unique N-glycosylation sites and 1567 unique N-glycopeptides from 684 N-glycoproteins were reliably characterized from 60μg protein sample extracted from mouse liver. Therefore, this maltose-functionalized polyethyleneimine coated adsorbent can play a promising role in highly efficient N-glycopeptides enrichment for glycoproteomic analyses of complex protein samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Dynamic T2-mapping during magnetic resonance guided high intensity focused ultrasound ablation of bone marrow

    Science.gov (United States)

    Waspe, Adam C.; Looi, Thomas; Mougenot, Charles; Amaral, Joao; Temple, Michael; Sivaloganathan, Siv; Drake, James M.

    2012-11-01

    Focal bone tumor treatments include amputation, limb-sparing surgical excision with bone reconstruction, and high-dose external-beam radiation therapy. Magnetic resonance guided high intensity focused ultrasound (MR-HIFU) is an effective non-invasive thermotherapy for palliative management of bone metastases pain. MR thermometry (MRT) measures the proton resonance frequency shift (PRFS) of water molecules and produces accurate (<1°C) and dynamic (<5s) thermal maps in soft tissues. PRFS-MRT is ineffective in fatty tissues such as yellow bone marrow and, since accurate temperature measurements are required in the bone to ensure adequate thermal dose, MR-HIFU is not indicated for primary bone tumor treatments. Magnetic relaxation times are sensitive to lipid temperature and we hypothesize that bone marrow temperature can be determined accurately by measuring changes in T2, since T2 increases linearly in fat during heating. T2-mapping using dual echo times during a dynamic turbo spin-echo pulse sequence enabled rapid measurement of T2. Calibration of T2-based thermal maps involved heating the marrow in a bovine femur and simultaneously measuring T2 and temperature with a thermocouple. A positive T2 temperature dependence in bone marrow of 20 ms/°C was observed. Dynamic T2-mapping should enable accurate temperature monitoring during MR-HIFU treatment of bone marrow and shows promise for improving the safety and reducing the invasiveness of pediatric bone tumor treatments.

  10. Accelerated Testing of High Temperature Permanent Magnets for Spacecraft Propulsion Project

    Data.gov (United States)

    National Aeronautics and Space Administration — High temperature permanent magnet materials play an important role in NASA's space missions in electric propulsion, energy generation and storage and other...

  11. A Magnetic Nanoparticle Based Enzyme-Linked Immunosorbent Assay for Sensitive Quantification of Zearalenone in Cereal and Feed Samples

    Directory of Open Access Journals (Sweden)

    Xian Zhang

    2015-10-01

    Full Text Available A novel enzyme-linked immunosorbent assay based on magnetic nanoparticles and biotin/streptavidin-HRP (MNP-bsELISA was developed for rapid and sensitive detection of zearalenone (ZEN. The detection signal was enhanced and the sensitivity of the assay was improved by combined use of antibody-conjugated magnetic nanoparticles and biotin-streptavidin system. Under the optimized conditions, the regression equation for quantification of ZEN was y = −0.4287x + 0.3132 (R2 = 0.9904. The working range was 0.07–2.41 ng/mL. The detection limit was 0.04 ng/mL and IC50 was 0.37 ng/mL. The recovery rates of intra-assay and inter-assay ranged from 92.8%–111.9% and 91.7%–114.5%, respectively, in spiked corn samples. Coefficients of variation were less than 10% in both cases. Parallel analysis of cereal and feed samples showed good correlation between MNP-bsELISA and liquid chromatograph-tandem mass spectrometry (R2 = 0.9283. We conclude that this method is suitable for rapid detection of zearalenone in cereal and feed samples in relevant laboratories.

  12. A Magnetic Nanoparticle Based Enzyme-Linked Immunosorbent Assay for Sensitive Quantification of Zearalenone in Cereal and Feed Samples.

    Science.gov (United States)

    Zhang, Xian; Wang, Xin; Sun, Mengjiao; Zhang, Xiaofeng; Song, Houhui; Yan, Yaxian; Sun, Jianhe; Li, Xiaoliang; Fang, Weihuan

    2015-10-20

    A novel enzyme-linked immunosorbent assay based on magnetic nanoparticles and biotin/streptavidin-HRP (MNP-bsELISA) was developed for rapid and sensitive detection of zearalenone (ZEN). The detection signal was enhanced and the sensitivity of the assay was improved by combined use of antibody-conjugated magnetic nanoparticles and biotin-streptavidin system. Under the optimized conditions, the regression equation for quantification of ZEN was y = -0.4287x + 0.3132 (R² = 0.9904). The working range was 0.07-2.41 ng/mL. The detection limit was 0.04 ng/mL and IC50 was 0.37 ng/mL. The recovery rates of intra-assay and inter-assay ranged from 92.8%-111.9% and 91.7%-114.5%, respectively, in spiked corn samples. Coefficients of variation were less than 10% in both cases. Parallel analysis of cereal and feed samples showed good correlation between MNP-bsELISA and liquid chromatograph-tandem mass spectrometry (R² = 0.9283). We conclude that this method is suitable for rapid detection of zearalenone in cereal and feed samples in relevant laboratories.

  13. Modification of magnetic anisotropy in metallic glasses using high ...

    Indian Academy of Sciences (India)

    Abstract. Heavy ion irradiation in the electronic stopping power region induces macroscopic di- mensional change in metallic glasses and introduces magnetic anisotropy in some magnetic mate- rials. The present work is on the irradiation study of ferromagnetic metallic glasses, where both dimensional change and ...

  14. Development of a high-performance magnetic gear

    DEFF Research Database (Denmark)

    Rasmussen, Peter Omand; Andersen, Torben Ole; Jørgensen, Frank Thorleif

    2005-01-01

    This paper presents calculation and measurement results of a highperformance permanent-magnetic gear. The analyzed permanent-magnetic gear has a gear ratio of 5.5 and is able to deliver 27 N.m. The analysis has shown that special attention needs to be paid to the system where the gear is to be in...

  15. High performance of low cost soft magnetic materials

    Indian Academy of Sciences (India)

    Administrator

    Abstract. The consistent interest in supporting research and development of magnetic materials during the last century is revealed in their steadily increasing market. In this work, the soft magnetic nanocrystalline. FINEMET alloy was prepared with commercial purity raw materials and compared for the first time with the.

  16. High-Field Magnetization of Light Rare-Earth Metals

    DEFF Research Database (Denmark)

    McEwen, K.A.; Cock, G.J.; Roeland, L.W.

    1973-01-01

    The magnetization of single crystals of Eu, Sm, Nd, Pr, and Pr-Nd alloys has been measured in fields up to 37 T (370 kG). The results give new information on the magnetic properties of these metals. Of particular interest is a first-order transition from a nonmagnetic to a metamagnetic phase...

  17. Highly sensitive vacuum ion pump current measurement system

    Science.gov (United States)

    Hansknecht, John Christopher [Williamsburg, VA

    2006-02-21

    A vacuum system comprising: 1) an ion pump; 2) power supply; 3) a high voltage DC--DC converter drawing power from the power supply and powering the vacuum pump; 4) a feedback network comprising an ammeter circuit including an operational amplifier and a series of relay controlled scaling resistors of different resistance for detecting circuit feedback; 5) an optional power block section intermediate the power supply and the high voltage DC--DC converter; and 6) a microprocessor receiving feedback information from the feedback network, controlling which of the scaling resistors should be in the circuit and manipulating data from the feedback network to provide accurate vacuum measurement to an operator.

  18. Magnetic Microcalorimeter (MMC) Gamma Detectors with Ultra-High Energy Resolution

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, Stephen [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2018-01-19

    The goal of this LCP is to develop ultra-high resolution gamma detectors based on magnetic microcalorimeters (MMCs) for accurate non-destructive analysis (NDA) of nuclear materials. For highest energy resolution, we will introduce erbium-doped silver (Ag:Er) as a novel sensor material, and implement several geometry and design changes to improve the signal-to-noise ratio. The detector sensitivity will be increased by developing arrays of 32 Ag:Er pixels read out by 16 SQUID preamplifiers, and by developing a cryogenic Compton veto to reduce the spectral background. Since best MMC performance requires detector operation at ~10 mK, we will purchase a dilution refrigerator with a base temperature <10 mK and adapt it for MMC operation. The detector performance will be tested with radioactive sources of interest to the safeguards community.

  19. High Sensitivity Indium Phosphide Based Avalanche Photodiode Focal Plane Arrays Project

    Data.gov (United States)

    National Aeronautics and Space Administration — nLight has demonstrated highly-uniform APD arrays based on the highly sensitive InGaAs/InP material system. These results provide great promise for achieving the...

  20. Thyroglobulin measurement using highly sensitive assays in patients with differentiated thyroid cancer:

    DEFF Research Database (Denmark)

    Giovanella, Luca; Clark, Penelope M; Chiovato, Luca

    2014-01-01

    stimulation by endogenous or exogenous TSH is recommended by current clinical guidelines to detect occult disease with a maximum sensitivity due to the suboptimal sensitivity of older Tg assays. However, the development of new highly sensitive Tg assays with improved analytical sensitivity and precision...... at low concentrations now allows detection of very low Tg concentrations reflecting minimal amounts of thyroid tissue without the need for TSH stimulation. Use of these highly sensitive Tg assays has not yet been incorporated into clinical guidelines but they will, we believe, be used by physicians...... caring for patients with DTC. The aim of this clinical position paper is, therefore, to offer advice on the various aspects and implications of using these highly sensitive Tg assays in the clinical care of patients with DTC....