WorldWideScience

Sample records for off-resonance saturation magnetic

  1. Evaluating Iron Content and Tissue Microstructure with Off-Resonance Saturation MRI

    Science.gov (United States)

    Fahmy, Sherif R.

    We present three magnetic resonance imaging (MRI) studies, each focused on applying off-resonance saturation (ORS) imaging to a different context or application. Particularly, we are interested in using ORS to evaluate the uptake of superparamagnetic MRI contrast agents in biological tissue, and to evaluate endogenous iron content. This relies on ORS being applied at low off-resonance frequency offsets where most of the negative contrast is due to signal loss from direct saturation of the water content of the sample. Additionally, we wish to combine this information with magnetization transfer contrast, which is obtained by applying ORS at offsets that are far from the resonance frequency, where magnetization transfer (MT) becomes the dominant effect rather than direct saturation (DS). In the first study, we observed the uptake of ultra-small superparamagnetic iron oxide (USPIO) nanoparticles in a simple model system by imaging the uptake in healthy murine liver in vivo, and by testing different metrics to quantify the uptake. Through this process, we discovered an approach that provides high sensitivity and specificity in low-signal scenarios. In the second study, we evaluated image contrast between brain regions in healthy human adults, and related these to the expected iron content in different regions based on age. Images were evaluated based on different MRI contrast mechanisms including quantitative transverse relaxation rates, as well as parameters obtained from ORS imaging. We also performed a field inhomogeneity adjustment on low-offset ORS data using the information obtained from the coarsely sampled ORS spectrum, and this was sufficient to correct for the inhomogeneities. In the third study, we used transverse relaxation, DS - which is strongly dependent on iron content, and MT contrast, in order to classify ex vivo brain samples having Alzheimer's disease pathology and normal controls, and were able to find strong classifiers. The three studies helped

  2. Multi-frequency interpolation in spiral magnetic resonance fingerprinting for correction of off-resonance blurring.

    Science.gov (United States)

    Ostenson, Jason; Robison, Ryan K; Zwart, Nicholas R; Welch, E Brian

    2017-09-01

    Magnetic resonance fingerprinting (MRF) pulse sequences often employ spiral trajectories for data readout. Spiral k-space acquisitions are vulnerable to blurring in the spatial domain in the presence of static field off-resonance. This work describes a blurring correction algorithm for use in spiral MRF and demonstrates its effectiveness in phantom and in vivo experiments. Results show that image quality of T1 and T2 parametric maps is improved by application of this correction. This MRF correction has negligible effect on the concordance correlation coefficient and improves coefficient of variation in regions of off-resonance relative to uncorrected measurements. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Diagnostic value of T1 and T2 * relaxation times and off-resonance saturation effects in the evaluation of Achilles tendinopathy by MRI at 3T.

    Science.gov (United States)

    Grosse, Ulrich; Syha, Roland; Hein, Tobias; Gatidis, Sergios; Grözinger, Gerd; Schabel, Christoph; Martirosian, Petros; Schick, Fritz; Springer, Fabian

    2015-04-01

    To evaluate and compare the diagnostic value of T1 , T2 * relaxation times and off-resonance saturation ratios (OSR) in healthy controls and patients with different clinical and morphological stages of Achilles tendinopathy. Forty-two healthy Achilles tendons and 34 tendons of 17 patients with symptomatic and asymptomatic tendinopathy were investigated clinically with conventional magnetic resonance imaging (MRI) sequences on a 3T whole-body MR scanner and a dynamic ultrasound examination. In addition, T1 and T2 * relaxation times were assessed using an ultrashort echo time (UTE) imaging sequence with flip angle and echo time variation. For the calculation of OSR values a Gaussian off-resonance saturation pulse (frequency offset: 750-5000 Hz) was used. The diagnostic value of the derived MR values was assessed and compared using receiver operating characteristic (ROC) curves. ROC curves demonstrate the highest overall test performance for OSR values at 2000 Hz off-resonance in differentiating slightly (OSR-2000 [AUC: 0.930] > T2 * [AUC: 0.884] > T1 [AUC: 0.737]) and more severe pathologically altered tendon areas (OSR-2000 [AUC: 0.964] > T2 * [AUC: 0.917] > T1 [AUC: 0.819]) from healthy ones. OSR values at a frequency offset of 2000 Hz demonstrated a better sensitivity and specificity for detecting mild and severe stages of tendinopathy compared to T2 * and particularly when compared to T1 relaxation times. © 2014 Wiley Periodicals, Inc.

  4. Intradiurnal fluctuations of off-resonance saturation effects in healthy human achilles tendons assessed with a 3D ultrashort echo time MRI sequence at 3 tesla

    Energy Technology Data Exchange (ETDEWEB)

    Grosse, U.; Syha, R.; Kessler, D.E.; Bongers, M.; Seith, F.; Nikolaou, K.; Springer, F. [University Hospital Tuebingen (Germany). Dept. of Diagnostic and Interventional Radiology; Partovi, S.; Robbin, M. [Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Radiology; Schick, F. [University Hospital Tuebingen (Germany). Section on Experimental Radiology

    2015-11-15

    The purpose of this study was to evaluate whether gravitational interstitial fluid accumulation in healthy subjects has an impact on off-resonance saturation ratios (OSR) or the volume of the Achilles tendon after a prolonged time of reduced levels of physical activity. 7 healthy volunteers were repeatedly investigated on 3 consecutive days on a 3 T whole body MR scanner using an ultrashort echo time (UTE) imaging sequence with a Gaussian off-resonance saturation pulse at a frequency offset of 2000 Hz to calculate OSR values. For accurate volumetric quantification of the Achilles tendon, a newly developed contour detection snake algorithm was applied on high-resolution isotropic T2-weighted SPACE sequence datasets. Single-measure intraclass correlation coefficients (ICC) were calculated to estimate test-retest reliability. For OSR and tendon volume measurements on three consecutive days, excellent reproducibility could be achieved with ICC values above 0.96 and 0.97, respectively. Comparing the results of all three days, a statistically significant mean individual percentage decrease (-4.1 ± 1.5 %; p=0.001) of calculated tendon OSR values was found for the evening measurements. No statistically significant difference between tendon volumes in the morning and the evening could be detected (p=0.589). The results of this in-vivo study demonstrate a significant influence of gravitational interstitial fluid accumulation after reduced physical activity on OSR values in the Achilles tendon, but not on tendon volume. Taken together with the demonstrated excellent reproducibility, these findings are important for future studies investigating temporal changes of the Achilles tendon microstructure.

  5. Intradiurnal fluctuations of off-resonance saturation effects in healthy human achilles tendons assessed with a 3D ultrashort echo time MRI sequence at 3 tesla

    International Nuclear Information System (INIS)

    Grosse, U.; Syha, R.; Kessler, D.E.; Bongers, M.; Seith, F.; Nikolaou, K.; Springer, F.; Partovi, S.; Robbin, M.; Schick, F.

    2015-01-01

    The purpose of this study was to evaluate whether gravitational interstitial fluid accumulation in healthy subjects has an impact on off-resonance saturation ratios (OSR) or the volume of the Achilles tendon after a prolonged time of reduced levels of physical activity. 7 healthy volunteers were repeatedly investigated on 3 consecutive days on a 3 T whole body MR scanner using an ultrashort echo time (UTE) imaging sequence with a Gaussian off-resonance saturation pulse at a frequency offset of 2000 Hz to calculate OSR values. For accurate volumetric quantification of the Achilles tendon, a newly developed contour detection snake algorithm was applied on high-resolution isotropic T2-weighted SPACE sequence datasets. Single-measure intraclass correlation coefficients (ICC) were calculated to estimate test-retest reliability. For OSR and tendon volume measurements on three consecutive days, excellent reproducibility could be achieved with ICC values above 0.96 and 0.97, respectively. Comparing the results of all three days, a statistically significant mean individual percentage decrease (-4.1 ± 1.5 %; p=0.001) of calculated tendon OSR values was found for the evening measurements. No statistically significant difference between tendon volumes in the morning and the evening could be detected (p=0.589). The results of this in-vivo study demonstrate a significant influence of gravitational interstitial fluid accumulation after reduced physical activity on OSR values in the Achilles tendon, but not on tendon volume. Taken together with the demonstrated excellent reproducibility, these findings are important for future studies investigating temporal changes of the Achilles tendon microstructure.

  6. Criteria for saturated magnetization loop

    International Nuclear Information System (INIS)

    Harres, A.; Mikhov, M.; Skumryev, V.; Andrade, A.M.H. de; Schmidt, J.E.; Geshev, J.

    2016-01-01

    Proper estimation of magnetization curve parameters is vital in studying magnetic systems. In the present article, criteria for discrimination non-saturated (minor) from saturated (major) hysteresis loops are proposed. These employ the analysis of (i) derivatives of both ascending and descending branches of the loop, (ii) remanent magnetization curves, and (iii) thermomagnetic curves. Computational simulations are used in order to demonstrate their validity. Examples illustrating the applicability of these criteria to well-known real systems, namely Fe_3O_4 and Ni fine particles, are provided. We demonstrate that the anisotropy-field value estimated from a visual examination of an only apparently major hysteresis loop could be more than two times lower than the real one. - Highlights: • Proper estimation of hysteresis-loop parameters is vital in magnetic studies. • We propose criteria for discrimination minor from major hysteresis loops. • The criteria analyze magnetization, remanence and ZFC/FC curves and/or their derivatives. • Examples of their application on real nanoparticles systems are given. • Using the criteria could avoid twofold or bigger saturation-field underestimation errors.

  7. Criteria for saturated magnetization loop

    Energy Technology Data Exchange (ETDEWEB)

    Harres, A. [Departamento de Física, UFSM, Santa Maria, 97105-900 Rio Grande do Sul (Brazil); Mikhov, M. [Faculty of Physics, University of Sofia, 1164 Sofia (Bulgaria); Skumryev, V. [Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona (Spain); Departament de Física, Universitat Autònoma de Barcelona, 08193 Barcelona (Spain); Andrade, A.M.H. de; Schmidt, J.E. [Instituto de Física, UFRGS, Porto Alegre, 91501-970 Rio Grande do Sul (Brazil); Geshev, J., E-mail: julian@if.ufrgs.br [Departament de Física, Universitat Autònoma de Barcelona, 08193 Barcelona (Spain); Instituto de Física, UFRGS, Porto Alegre, 91501-970 Rio Grande do Sul (Brazil)

    2016-03-15

    Proper estimation of magnetization curve parameters is vital in studying magnetic systems. In the present article, criteria for discrimination non-saturated (minor) from saturated (major) hysteresis loops are proposed. These employ the analysis of (i) derivatives of both ascending and descending branches of the loop, (ii) remanent magnetization curves, and (iii) thermomagnetic curves. Computational simulations are used in order to demonstrate their validity. Examples illustrating the applicability of these criteria to well-known real systems, namely Fe{sub 3}O{sub 4} and Ni fine particles, are provided. We demonstrate that the anisotropy-field value estimated from a visual examination of an only apparently major hysteresis loop could be more than two times lower than the real one. - Highlights: • Proper estimation of hysteresis-loop parameters is vital in magnetic studies. • We propose criteria for discrimination minor from major hysteresis loops. • The criteria analyze magnetization, remanence and ZFC/FC curves and/or their derivatives. • Examples of their application on real nanoparticles systems are given. • Using the criteria could avoid twofold or bigger saturation-field underestimation errors.

  8. Iron saturation control in RHIC dipole magnets

    International Nuclear Information System (INIS)

    Thompson, P.A.; Gupta, R.C.; Kahn, S.A.; Hahn, H.; Morgan, G.H.; Wanderer, P.J.; Willen, E.

    1991-01-01

    The Relativistic Heavy Ion Collider (RHIC) will require 360 dipoles of 80 mm bore. This paper discusses the field perturbations produced by the saturation of the yoke iron. Changes have been made to the yoke to reduce these perturbations, in particular, decapole -4 . Measurements and calculations for 6 series of dipole magnets are presented. 2 refs., 2 figs., 1 tab

  9. Magnetic field saturation in the Riga dynamo experiment.

    Science.gov (United States)

    Gailitis, A; Lielausis, O; Platacis, E; Dement'ev, S; Cifersons, A; Gerbeth, G; Gundrum, T; Stefani, F; Christen, M; Will, G

    2001-04-02

    After the dynamo experiment in November 1999 [A. Gailitis et al., Phys. Rev. Lett. 84, 4365 (2000)] had shown magnetic field self-excitation in a spiraling liquid metal flow, in a second series of experiments emphasis was placed on the magnetic field saturation regime as the next principal step in the dynamo process. The dependence of the strength of the magnetic field on the rotation rate is studied. Various features of the saturated magnetic field are outlined and possible saturation mechanisms are discussed.

  10. Preparation of hydrophilic magnetic nanospheres with high saturation magnetization

    International Nuclear Information System (INIS)

    Xu Hong; Tong Naihu; Cui Longlan; Lu Ying; Gu Hongchen

    2007-01-01

    Well-defined silica-magnetite core-shell nanospheres were prepared via a modified sol-gel method. Sphere-like magnetite aggregates were obtained as cores of the final nanospheres by assembling in the presence of Tween 20. Characterization by transmission electron microscopy (TEM) showed spherical morphology of the nanospheres with controlled silica shell thickness from 9 to 30 nm, depending on the amount of tetraethoxysilane (TEOS) used. The nanospheres contained up to 41.7 wt% magnetite with a saturation magnetization of 21.8 emu/g. Up to 35 μg/mg of the model biomolecule streptavidin (SA) could be bound covalently to the hydrophilic silica nanospheres

  11. SATURATION OF MAGNETOROTATIONAL INSTABILITY THROUGH MAGNETIC FIELD GENERATION

    International Nuclear Information System (INIS)

    Ebrahimi, F.; Prager, S. C.; Schnack, D. D.

    2009-01-01

    The saturation mechanism of magnetorotational instability (MRI) is examined through analytical quasi-linear theory and through nonlinear computation of a single mode in a rotating disk. We find that large-scale magnetic field is generated through the α-effect (the correlated product of velocity and magnetic field fluctuations) and causes the MRI mode to saturate. If the large-scale plasma flow is allowed to evolve, the mode can also saturate through its flow relaxation. In astrophysical plasmas, for which the flow cannot relax because of gravitational constraints, the mode saturates through field generation only.

  12. New insight in magnetic saturation behavior of nickel hierarchical structures

    Science.gov (United States)

    Ma, Ji; Zhang, Jianxing; Liu, Chunting; Chen, Kezheng

    2017-09-01

    It is unanimously accepted that non-ferromagnetic inclusions in a ferromagnetic system will lower down total saturation magnetization in unit of emu/g. In this study, ;lattice strain; was found to be another key factor to have critical impact on magnetic saturation behavior of the system. The lattice strain determined assembling patterns of primary nanoparticles in hierarchical structures and was intimately related with the formation process of these architectures. Therefore, flower-necklace-like and cauliflower-like nickel hierarchical structures were used as prototype systems to evidence the relationship between assembling patterns of primary nanoparticles and magnetic saturation behaviors of these architectures. It was found that the influence of lattice strain on saturation magnetization outperformed that of non-ferromagnetic inclusions in these hierarchical structures. This will enable new insights into fundamental understanding of related magnetic effects.

  13. Modelling a linear PM motor including magnetic saturation

    NARCIS (Netherlands)

    Polinder, H.; Slootweg, J.G.; Compter, J.C.; Hoeijmakers, M.J.

    2002-01-01

    The use of linear permanent-magnet (PM) actuators increases in a wide variety of applications because of the high force density, robustness and accuracy. The paper describes the modelling of a linear PM motor applied in, for example, wafer steppers, including magnetic saturation. This is important

  14. Inversion degree and saturation magnetization of different nanocrystalline cobalt ferrites

    International Nuclear Information System (INIS)

    Concas, G.; Spano, G.; Cannas, C.; Musinu, A.; Peddis, D.; Piccaluga, G.

    2009-01-01

    The inversion degree of a series of nanocrystalline samples of CoFe 2 O 4 ferrites has been evaluated by a combined study, which exploits the saturation magnetization at 4.2 K and 57 Fe Moessbauer spectroscopy. The samples, prepared by sol-gel autocombustion, have different thermal history and particle size. The differences observed in the saturation magnetization of these samples are explained in terms of different inversion degrees, as confirmed by the analysis of the components in the Moessbauer spectra. It is notable that the inversion degrees of the samples investigated are set among the highest values reported in the literature.

  15. 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%.

  16. Minnealloy: a new magnetic material with high saturation flux density and low magnetic anisotropy

    Science.gov (United States)

    Mehedi, Md; Jiang, Yanfeng; Suri, Pranav Kumar; Flannigan, David J.; Wang, Jian-Ping

    2017-09-01

    We are reporting a new soft magnetic material with high saturation magnetic flux density, and low magnetic anisotropy. The new material is a compound of iron, nitrogen and carbon, α‧-Fe8(NC), which has saturation flux density of 2.8  ±  0.15 T and magnetic anisotropy of 46 kJ m-3. The saturation flux density is 27% higher than pure iron, a widely used soft magnetic material. Soft magnetic materials are very important building blocks of motors, generators, inductors, transformers, sensors and write heads of hard disk. The new material will help in the miniaturization and efficiency increment of the next generation of electronic devices.

  17. High saturation magnetization FeB(C) nanocapsules

    International Nuclear Information System (INIS)

    Ma, S.; Si, P.Z.; Zhang, Y.; Wu, B.; Li, Y.B.; Liu, J.J.; Feng, W.J.; Ma, X.L.; Zhang, Z.D.

    2007-01-01

    FeB(C) nanocapsules were prepared by arc-discharging Fe 80 B 20 alloy in Ar and CH 4 . X-ray diffraction and transmission electron microscopy analyses showed that the FeB(C) nanocapsules had a core-shell structure with α-Fe and Fe 3 B as cores and graphite as shells. The formation mechanism of the FeB(C) nanocapsules is discussed. The graphite shells display a strong anti-acid effect. The saturation magnetization at room temperature of the FeB(C) nanocapsules is much higher than that of Fe(B) nanocapsules. The blocking temperature of FeB(C) nanocapsules is above 300 K

  18. The effect of saturation magnetization of nanocatalyst and oscillating magnetic field for green urea synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Yahya, Noorhana, E-mail: noorhana_yahya@petronas.com.my; Alqasem, Bilal, E-mail: bilalalqasem@yahoo.com; Irfan, Muhammad; Qureshi, Saima; Rehman, Zia Ur; Shafie, Afza; Soleimani, Hassan

    2017-02-15

    Hematite and cupric oxide nanowires have been synthesized using the oxidation method for green urea production. Hematite nanowires were obtained by the oxidation of an iron wire at a temperature of 650 °C and ambient pressure in the presence of N{sub 2} and O{sub 2} gases. Cupric oxide nanowires were obtained by the same method at 700 °C, using a copper wire. The X-ray diffraction results show the formation of rhombohedral structure of α-Fe{sub 2}O{sub 3} and monoclinic phase of CuO. FE-SEM results reveal the formation of nanowires with dimensions ranging between 5–15 µm and 4–12 µm in length and a diametere ranging between 50–150 nm and 50–250 nm for α-Fe{sub 2}O{sub 3} and CuO respectively. The VSM results show that the saturation magnetization values for hematite and cupric oxide were 132.8700 and 0.0124 emu/g, respectively. The nanowires were used as catalyst for green urea synthesis in the presence of an oscillating and a static magnetic fields. The use of nanocatalyst with high saturation magnetization gives a higher yield of urea due to the increase in the singlet to triplet conversion. The highest yield of urea 11243 ppm was achieved by applying an oscillating magnetic field of frequency 0.5 MHz and using α-Fe{sub 2}O{sub 3} nanowires as nanocatalyst. - Highlights: • Effect of saturation magnetization of nanocatalyst on urea yield was investigated • Using nanocatalyst with high saturation magnetization value improved urea yield. • Effect of oscillating magnetic field frequency on the urea yield was investigated. • The highest urea yield was achieved by applying 0.5 MHz oscillating magnetic field.

  19. The effect of saturation magnetization of nanocatalyst and oscillating magnetic field for green urea synthesis

    International Nuclear Information System (INIS)

    Yahya, Noorhana; Alqasem, Bilal; Irfan, Muhammad; Qureshi, Saima; Rehman, Zia Ur; Shafie, Afza; Soleimani, Hassan

    2017-01-01

    Hematite and cupric oxide nanowires have been synthesized using the oxidation method for green urea production. Hematite nanowires were obtained by the oxidation of an iron wire at a temperature of 650 °C and ambient pressure in the presence of N 2 and O 2 gases. Cupric oxide nanowires were obtained by the same method at 700 °C, using a copper wire. The X-ray diffraction results show the formation of rhombohedral structure of α-Fe 2 O 3 and monoclinic phase of CuO. FE-SEM results reveal the formation of nanowires with dimensions ranging between 5–15 µm and 4–12 µm in length and a diametere ranging between 50–150 nm and 50–250 nm for α-Fe 2 O 3 and CuO respectively. The VSM results show that the saturation magnetization values for hematite and cupric oxide were 132.8700 and 0.0124 emu/g, respectively. The nanowires were used as catalyst for green urea synthesis in the presence of an oscillating and a static magnetic fields. The use of nanocatalyst with high saturation magnetization gives a higher yield of urea due to the increase in the singlet to triplet conversion. The highest yield of urea 11243 ppm was achieved by applying an oscillating magnetic field of frequency 0.5 MHz and using α-Fe 2 O 3 nanowires as nanocatalyst. - Highlights: • Effect of saturation magnetization of nanocatalyst on urea yield was investigated • Using nanocatalyst with high saturation magnetization value improved urea yield. • Effect of oscillating magnetic field frequency on the urea yield was investigated. • The highest urea yield was achieved by applying 0.5 MHz oscillating magnetic field.

  20. Effect of partial saturation of bonded neo magnet on the automotive accessory motor

    Directory of Open Access Journals (Sweden)

    Nimitkumar K. Sheth

    2017-05-01

    Full Text Available In this paper the effects of using a partially magnetized bonded neo (NdFeB magnet in an automotive accessory motor are presented. The potential reason for partial saturation of the bonded neo magnet is explained and a simple method to ensure saturation of the magnet is discussed. A magnetizing fixture design using the 2-D Finite element analysis (FEA is presented. The motor performance at various magnet saturation levels has been estimated using the 2-D FEA. Details of the thermal demagnetization test adopted by the automotive industry is also discussed and results of the motor performance for four saturation levels are detailed. These results indicate that the effect of demagnetization is more adverse in a motor with partially saturated magnets.

  1. Effect of partial saturation of bonded neo magnet on the automotive accessory motor

    Science.gov (United States)

    Sheth, Nimitkumar K.; Angara, Raghu C. S. Babu

    2017-05-01

    In this paper the effects of using a partially magnetized bonded neo (NdFeB) magnet in an automotive accessory motor are presented. The potential reason for partial saturation of the bonded neo magnet is explained and a simple method to ensure saturation of the magnet is discussed. A magnetizing fixture design using the 2-D Finite element analysis (FEA) is presented. The motor performance at various magnet saturation levels has been estimated using the 2-D FEA. Details of the thermal demagnetization test adopted by the automotive industry is also discussed and results of the motor performance for four saturation levels are detailed. These results indicate that the effect of demagnetization is more adverse in a motor with partially saturated magnets.

  2. High energy resolution off-resonant X-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wojciech, Blachucki [Univ. of Fribourg (Switzerland). Dept. of Physics

    2015-10-16

    This work treats of the high energy resolution off-resonant X-ray spectroscopy (HEROS) method of determining the density of unoccupied electronic states in the vicinity of the absorption edge. HEROS is an alternative to the existing X-ray absorption spectroscopy (XAS) methods and opens the way for new studies not achievable before.

  3. Torque Analysis With Saturation Effects for Non-Salient Single-Phase Permanent-Magnet Machines

    DEFF Research Database (Denmark)

    Lu, Kaiyuan; Ritchie, Ewen

    2011-01-01

    The effects of saturation on torque production for non-salient, single-phase, permanent-magnet machines are studied in this paper. An analytical torque equation is proposed to predict the instantaneous torque with saturation effects. Compared to the existing methods, it is computationally faster......-element results, and experimental results obtained on a prototype single-phase permanent-magnet machine....

  4. Synthesis of FeSiBPNbCu nanocrystalline soft-magnetic alloys with high saturation magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zongzhen [China Iron and Steel Research Institute Group, Advanced Technology and Materials Co., Ltd., Beijing 100081 (China); Wang, Anding; Chang, Chuntao [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, 519 Zhuangshi Road, Zhenhai District, Ningbo, Zhejiang 315201 (China); Wang, Yanguo [Institute of Physics, Chinese Academy of Sciences, PO Box 603, Beijing 100080 (China); Dong, Bangshao [China Iron and Steel Research Institute Group, Advanced Technology and Materials Co., Ltd., Beijing 100081 (China); Zhou, Shaoxiong, E-mail: sxzhou@atmcn.com [China Iron and Steel Research Institute Group, Advanced Technology and Materials Co., Ltd., Beijing 100081 (China)

    2014-10-25

    Highlights: • Thermal stability of the FeSiBPNbCu alloys is strongly dependent on the Fe content. • The FeSiBPNbCu alloys with high Fe content exhibit good soft magnetic properties. • The coexistence of Cu, P and Nb leads to the excellent soft magnetic properties. - Abstract: A series of [Fe{sub 0.76+x}(Si{sub 0.4}B{sub 0.4}P{sub 0.2}){sub 0.24−x}]{sub 98.25}Nb{sub 1}Cu{sub 0.75} (x = 0–0.08) nanocrystalline soft-magnetic alloys with high saturation magnetization were synthesized by adjusting Fe content and improving the crystallization behavior, soft-magnetic properties and microstructure. It is found that the temperature interval between the two crystallization peaks is significantly enlarged from 50 to 180 °C when the Fe content of the alloys increases from x = 0 to x = 0.08, which greatly expands the optimum annealing temperature range. The alloys with higher Fe content are prone to form more uniform nanocomposite microstructure with better thermal stability and soft magnetic properties. The Fe-rich FeSiBPNbCu nanocrystalline alloys with x = 0.08 exhibit excellent soft-magnetic properties, including the high saturation magnetic flux density of up to 1.74 T, low coercivity of about 3.3 A/m and high effective permeability of more than 2.2 × 10{sup 4} at 1 kHz under a field of 1 A/m. The combination of excellent soft-magnetic properties, low cost and good productivity makes the FeSiBPNbCu alloys to be a kind of promising soft-magnetic materials for electrical and electronic industry applications.

  5. Impact of magnetic saturation on the input-output linearising tracking control of an induction motor

    DEFF Research Database (Denmark)

    Dolinar, Drago; Ljusev, Petar; Stumberger, Gorazd

    2004-01-01

    This paper deals with the tracking control design of an induction motor, based on input-output linearization with magnetic saturation included. Magnetic saturation is represented by the nonlinear magnetizing curve of the iron core and is used in the control design, the observer of state variables......, and in the load torque estimator. An input-output linearising control is used to achieve better tracking performances of the drive. It is based on the mixed ”stator current - rotor flux linkage” induction motor model with magnetic saturation considered in the stationary reference frame. Experimental results show...... that the proposed input-output linearising tracking control with the included saturation behaves considerably better than the one without saturation, and that it introduces smaller position and speed errors, and better motor stiffness on account of the increased computational complexity....

  6. 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...

  7. Input-output linearizing tracking control of induction machine with the included magnetic saturation

    DEFF Research Database (Denmark)

    Dolinar, Drago; Ljusev, Petar; Stumberger, Gorazd

    2003-01-01

    The tracking control design of an induction motor, based on input-output linearisation with magnetic saturation included is addressed. The magnetic saturation is represented by a nonlinear magnetising curve for the iron core and is used in the control, the observer of the state variables......, and in the load torque estimator. An input-output linearising control is used to achieve better tracking performances. It is based on the mixed 'stator current - rotor flux linkage' induction motor model with magnetic saturation considered in the stationary reference frame. Experimental results show...... that the proposed input-output linearising tracking control with saturation included behaves considerably better than the one without saturation, and that it introduces smaller position and speed errors, and better motor stiffness on account of the increased computational complexity....

  8. Precision polarization measurements of atoms in a far-off-resonance optical dipole trap

    International Nuclear Information System (INIS)

    Fang, F.; Vieira, D. J.; Zhao, X.

    2011-01-01

    Precision measurement of atomic and nuclear polarization is an essential step for beta-asymmetry measurement of radioactive atoms. In this paper, we report the polarization measurement of Rb atoms in an yttrium-aluminum-garnet (YAG) far-off-resonance optical dipole trap. We have prepared a cold cloud of polarized Rb atoms in the YAG dipole trap by optical pumping and achieved an initial nuclear polarization of up to 97.2(5)%. The initial atom distribution in different Zeeman levels is measured by using a combination of microwave excitation, laser pushing, and atomic retrap techniques. The nuclear-spin polarization is further purified to 99.2(2)% in 10 s and maintained above 99% because the two-body collision loss rate between atoms in mixed spin states is greater than the one-body trap loss rate. Systematic effects on the nuclear polarization, including the off-resonance Raman scattering, magnetic field gradient, and background gas collisions, are discussed.

  9. Criterion of magnetic saturation and simulation of nonlinear magnetization for a linear multi-core pulse transformer

    International Nuclear Information System (INIS)

    Zeng Zhengzhong; Kuai Bin; Sun Fengju; Cong Peitian; Qiu Aici

    2002-01-01

    The linear multi-core pulse transformer is an important primary driving source used in pulsed power apparatus for the production of dense plasm owing to its compact, relatively low-cost and easy-to-handle characteristics. The evaluation of the magnetic saturation of the transformer cores is essential to the transformer design, because the energy transfer efficiency of the transformer will degrade significantly after magnetic saturation. This work proposes analytical formulas of the criterion of magnetic saturation for the cores when the transformer drives practical loads. Furthermore, an electric circuit model based on a dependent source treatment for simulating the electric behavior of the cores related to their nonlinear magnetization is developed using the initial magnetization curve of the cores. The numerical simulation with the model is used to evaluate the validity of the criterion. Both the criterion and the model are found to be in agreement with the experimental data

  10. Preparation of Magnetic Iron Oxide Nanoparticles (MIONs with Improved Saturation Magnetization Using Multifunctional Polymer Ligand

    Directory of Open Access Journals (Sweden)

    Muhammad Irfan Majeed

    2016-11-01

    Full Text Available This paper describes the preparation of ultra-small magnetic iron oxide (Fe3O4 nanoparticles (MIONs coated with water-soluble thioether end-functionalized polymer ligand pentaerythritol tetrakis 3-mercaptopropionate-polymethacrylic acid (PTMP-PMAA. The MIONs were prepared by co-precipitation of aqueous iron precursor solution at a high temperature. The polymer modified MIONs were characterized by dynamic light scattering (DLS, transmission electron microscopy (TEM, Fourier transform infrared spectroscopy (FTIR, X-ray powder diffraction (XRD, thermogravimetric analysis (TGA, and vibrating sample magnetometery (VSM. It was found that these MIONs were successfully modified by this water-soluble polymer ligand with a fairly uniform size and narrow size distribution. The dried powder of MIONs could be stored for a long time and re-dispersed well in water without any significant change. Additionally, the polymer concentration showed a significant effect on size and magnetic properties of the MIONs. The saturation magnetization was increased by optimizing the polymer concentration. Furthermore, the 3-(4,5-dimethylthiazol-2-yl-2-5-diphenyltetrazolium bromide (MTT-assay demonstrated that these MIONs were highly biocompatible and they could be successfully coupled with fluorescent dye Rhodamine due to the formation of amide bond between carboxylic acid groups of MIONs and amine groups of dye. The obtained results indicated that these multifunctional MIONs with rich surface chemistry exhibit admirable potential in biomedical applications.

  11. Optimization design of toroidal core for magnetic energy harvesting near power line by considering saturation effect

    Science.gov (United States)

    Park, Bumjin; Kim, Dongwook; Park, Jaehyoung; Kim, Kibeom; Koo, Jay; Park, HyunHo; Ahn, Seungyoung

    2018-05-01

    Recently, magnetic energy harvesting technologies have been studied actively for self-sustainable operation of applications around power line. However, magnetic energy harvesting around power lines has the problem of magnetic saturation, which can cause power performance degradation of the harvester. In this paper, optimal design of a toroidal core for magnetic energy harvesters has been proposed with consideration of magnetic saturation near power lines. Using Permeability-H curve and Ampere's circuital law, the optimum dimensional parameters needed to generate induced voltage were analyzed via calculation and simulation. To reflect a real environment, we consider the nonlinear characteristic of the magnetic core material and supply current through a 3-phase distribution panel used in the industry. The effectiveness of the proposed design methodology is verified by experiments in a power distribution panel and takes 60.9 V from power line current of 60 A at 60 Hz.

  12. Analytical model and design of spoke-type permanent-magnet machines accounting for saturation and nonlinearity of magnetic bridges

    Science.gov (United States)

    Liang, Peixin; Chai, Feng; Bi, Yunlong; Pei, Yulong; Cheng, Shukang

    2016-11-01

    Based on subdomain model, this paper presents an analytical method for predicting the no-load magnetic field distribution, back-EMF and torque in general spoke-type motors with magnetic bridges. Taking into account the saturation and nonlinearity of magnetic material, the magnetic bridges are equivalent to fan-shaped saturation regions. For getting standard boundary conditions, a lumped parameter magnetic circuit model and iterative method are employed to calculate the permeability. The final field domain is divided into five types of simple subdomains. Based on the method of separation of variables, the analytical expression of each subdomain is derived. The analytical results of the magnetic field distribution, Back-EMF and torque are verified by finite element method, which confirms the validity of the proposed model for facilitating the motor design and optimization.

  13. Studies on diagnosis of endometriosis by magnetic resonance imaging by means of fat saturation techniques

    International Nuclear Information System (INIS)

    Okada, Saori

    1995-01-01

    It is difficult to distinguish a small endometrial implant from adipose tissue by magnetic resonance imaging (MRI). I assessed the usefulness of fat saturated MRI in detecting small endometrial implants by comparing it with conventional MRI. Seventy-four patients with clinically suspected endometriosis were referred for MRI. In every patient, laparoscopy or laparotomy was performed. MRI was performed with a 1.5 T superconducting magnet with spin echo T1, T2 and fat saturated T1 weighted images. Surgery revealed a normal pelvis in 6 patients, endometriosis in 65, and cystic lesions in three others. With fat saturated MRI, overall sensitivity, specificity, positive predictive value and negative predictive value were 87.7%, 66.7%, 95.0% and 42.9%, respectively. At surgery, 160 pigmented lesions of endometriosis were detected. Conventional MRI permitted identification of almost all ovarian endometriomas >10 mm in diameter, as with fat saturated MRI. With conventional MRI, 18 endometrial implant lesions <10 mm in diameter were detected. Including those detected by fat saturated MRI, altogether 42 lesions were detected. Conventional MRI demonstrated only 3 lesions among the 48 blueberry spots, but the additional fat saturated MRI technique increased the detection rate to 21 out of 48. Fat saturated MRI can therefore be used for detecting small endometrial implants. (author)

  14. Studies on diagnosis of endometriosis by magnetic resonance imaging by means of fat saturation techniques

    Energy Technology Data Exchange (ETDEWEB)

    Okada, Saori [Shimane Medical Univ., Izumo (Japan)

    1995-03-01

    It is difficult to distinguish a small endometrial implant from adipose tissue by magnetic resonance imaging (MRI). I assessed the usefulness of fat saturated MRI in detecting small endometrial implants by comparing it with conventional MRI. Seventy-four patients with clinically suspected endometriosis were referred for MRI. In every patient, laparoscopy or laparotomy was performed. MRI was performed with a 1.5 T superconducting magnet with spin echo T1, T2 and fat saturated T1 weighted images. Surgery revealed a normal pelvis in 6 patients, endometriosis in 65, and cystic lesions in three others. With fat saturated MRI, overall sensitivity, specificity, positive predictive value and negative predictive value were 87.7%, 66.7%, 95.0% and 42.9%, respectively. At surgery, 160 pigmented lesions of endometriosis were detected. Conventional MRI permitted identification of almost all ovarian endometriomas >10 mm in diameter, as with fat saturated MRI. With conventional MRI, 18 endometrial implant lesions <10 mm in diameter were detected. Including those detected by fat saturated MRI, altogether 42 lesions were detected. Conventional MRI demonstrated only 3 lesions among the 48 blueberry spots, but the additional fat saturated MRI technique increased the detection rate to 21 out of 48. Fat saturated MRI can therefore be used for detecting small endometrial implants. (author).

  15. SATDSK: a numerical simulation of the magnetic field due to saturated iron in cyclotron poletips

    International Nuclear Information System (INIS)

    McNeilly, G.S.

    1979-10-01

    SATDSK is a computer program, written in FORTRAN, which calculates the median plane magnetic field due to fully saturated iron poletips. Optionally, SATDSK calculates the magnetic field due to disks of magnetic charge, which can simulate the effect of holes in the iron poletip, or circular trim rods embedded in the poletip. SATDSK is intended for poletip geometries that are both symmetric about the median plane, and have azimuthal sector symmetry. Thus, the program is primarily designed to simulate the magnetic field due to iron poletips in superconducting cyclotrons

  16. Effect of saturating ferrite on the field in a prototype kicker magnet

    International Nuclear Information System (INIS)

    Barnes, M.J.; Wait, G.D.

    1994-06-01

    The field rise for kicker magnets is often specified between 1% and 99% of full strength. Three-gap thyratrons are frequently used as switches for kicker magnet systems. These thyratrons turn on in three stages: the collapse of voltage across one gap causes a displacement current to flow in the parasitic capacitance of off-state gap(s). The displacement current flows in the external circuit and can thus increase the effective rise-time of the field in the kicker magnet. One promising method of decreasing the effect of the displacement current involves the use of saturating ferrites. Another method for achieving the specified rise-time and 'flatness' for the kick strength is to utilize speed-up networks in the electrical circuit. Measurements have been carried out on a prototype kicker magnet with a speed-up network and various geometries of saturating ferrite. Measurements and PSpice calculations are presented. (author)

  17. Size Reduction of a DC Link Choke Using Saturation Gap and Biasing with Permanent Magnets

    DEFF Research Database (Denmark)

    Aguilar, Andres Revilla; Munk-Nielsen, Stig; Zuccherato, Marco

    2014-01-01

    This document describes the design procedure of permanent magnet biased DC inductors using the Saturation-gap technique [1]. This biasing configuration can provide a 50% reduction in either the core volume or the number of turns, while meeting its current and inductance requirements. A design exa...

  18. Magnetic properties of natural pyrrhotite Part I : Behaviour of initial susceptibility and saturation-magnetization-related rock-magnetic parameters in a grain-size dependent framework

    NARCIS (Netherlands)

    Dekkers, M.J.

    1988-01-01

    The grain-size dependence of the initial susceptibility, saturation magnetization, saturation remanence , coercive force, remanent coercive force and remanent acquisition coercive force, is reported for four natural pyrrhotites in a grain-size range from 250 µm down to <5 µm.

  19. Analytical model and design of spoke-type permanent-magnet machines accounting for saturation and nonlinearity of magnetic bridges

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Peixin; Chai, Feng [State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150001 (China); Department of Electrical Engineering, Harbin Institute of Technology, Harbin 150001 (China); Bi, Yunlong [Department of Electrical Engineering, Harbin Institute of Technology, Harbin 150001 (China); Pei, Yulong, E-mail: peiyulong1@163.com [Department of Electrical Engineering, Harbin Institute of Technology, Harbin 150001 (China); Cheng, Shukang [State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150001 (China); Department of Electrical Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2016-11-01

    Based on subdomain model, this paper presents an analytical method for predicting the no-load magnetic field distribution, back-EMF and torque in general spoke-type motors with magnetic bridges. Taking into account the saturation and nonlinearity of magnetic material, the magnetic bridges are equivalent to fan-shaped saturation regions. For getting standard boundary conditions, a lumped parameter magnetic circuit model and iterative method are employed to calculate the permeability. The final field domain is divided into five types of simple subdomains. Based on the method of separation of variables, the analytical expression of each subdomain is derived. The analytical results of the magnetic field distribution, Back-EMF and torque are verified by finite element method, which confirms the validity of the proposed model for facilitating the motor design and optimization. - Highlights: • The no-load magnetic field of poke-type motors is firstly calculated by analytical method. • The magnetic circuit model and iterative method are employed to calculate the permeability. • The analytical expression of each subdomain is derived.. • The proposed method can effectively reduce the predesign stages duration.

  20. Analytical model and design of spoke-type permanent-magnet machines accounting for saturation and nonlinearity of magnetic bridges

    International Nuclear Information System (INIS)

    Liang, Peixin; Chai, Feng; Bi, Yunlong; Pei, Yulong; Cheng, Shukang

    2016-01-01

    Based on subdomain model, this paper presents an analytical method for predicting the no-load magnetic field distribution, back-EMF and torque in general spoke-type motors with magnetic bridges. Taking into account the saturation and nonlinearity of magnetic material, the magnetic bridges are equivalent to fan-shaped saturation regions. For getting standard boundary conditions, a lumped parameter magnetic circuit model and iterative method are employed to calculate the permeability. The final field domain is divided into five types of simple subdomains. Based on the method of separation of variables, the analytical expression of each subdomain is derived. The analytical results of the magnetic field distribution, Back-EMF and torque are verified by finite element method, which confirms the validity of the proposed model for facilitating the motor design and optimization. - Highlights: • The no-load magnetic field of poke-type motors is firstly calculated by analytical method. • The magnetic circuit model and iterative method are employed to calculate the permeability. • The analytical expression of each subdomain is derived.. • The proposed method can effectively reduce the predesign stages duration.

  1. Subcritical saturation of the magnetorotational instability through mean magnetic field generation

    Science.gov (United States)

    Xie, Jin-Han; Julien, Keith; Knobloch, Edgar

    2018-03-01

    The magnetorotational instability is widely believed to be responsible for outward angular momentum transport in astrophysical accretion discs. The efficiency of this transport depends on the amplitude of this instability in the saturated state. We employ an asymptotic expansion based on an explicit, astrophysically motivated time-scale separation between the orbital period, Alfvén crossing time and viscous or resistive dissipation time-scales, originally proposed by Knobloch and Julien, to formulate a semi-analytical description of the saturated state in an incompressible disc. In our approach a Keplerian shear flow is maintained by the central mass but the instability saturates via the generation of a mean vertical magnetic field. The theory assumes that the time-averaged angular momentum flux and the radial magnetic flux are constant and determines both self-consistently. The results predict that, depending on parameters, steady saturation may be supercritical or subcritical, and in the latter case that the upper (lower) solution branch is always stable (unstable). The angular momentum flux is always outward, consistent with the presence of accretion, and for fixed wavenumber peaks in the subcritical regime. The limit of infinite Reynolds number at large but finite magnetic Reynolds number is also discussed.

  2. PRO-QUEST: a rapid assessment method based on progressive saturation for quantifying exchange rates using saturation times in CEST.

    Science.gov (United States)

    Demetriou, Eleni; Tachrount, Mohamed; Zaiss, Moritz; Shmueli, Karin; Golay, Xavier

    2018-03-05

    To develop a new MRI technique to rapidly measure exchange rates in CEST MRI. A novel pulse sequence for measuring chemical exchange rates through a progressive saturation recovery process, called PRO-QUEST (progressive saturation for quantifying exchange rates using saturation times), has been developed. Using this method, the water magnetization is sampled under non-steady-state conditions, and off-resonance saturation is interleaved with the acquisition of images obtained through a Look-Locker type of acquisition. A complete theoretical framework has been set up, and simple equations to obtain the exchange rates have been derived. A reduction of scan time from 58 to 16 minutes has been obtained using PRO-QUEST versus the standard QUEST. Maps of both T 1 of water and B 1 can simply be obtained by repetition of the sequence without off-resonance saturation pulses. Simulations and calculated exchange rates from experimental data using amino acids such as glutamate, glutamine, taurine, and alanine were compared and found to be in good agreement. The PRO-QUEST sequence was also applied on healthy and infarcted rats after 24 hours, and revealed that imaging specificity to ischemic acidification during stroke was substantially increased relative to standard amide proton transfer-weighted imaging. Because of the reduced scan time and insensitivity to nonchemical exchange factors such as direct water saturation, PRO-QUEST can serve as an excellent alternative for researchers and clinicians interested to map pH changes in vivo. © 2018 International Society for Magnetic Resonance in Medicine.

  3. Speed control of switched reluctance motors taking into account mutual inductances and magnetic saturation effects

    Energy Technology Data Exchange (ETDEWEB)

    Alrifai, M., E-mail: alrifm@eng.kuniv.edu.k [Electrical Engineering Department, College of Engineering and Petroleum, Kuwait University, P.O. Box 5969, Safat 13060 (Kuwait); Zribi, M.; Rayan, M. [Electrical Engineering Department, College of Engineering and Petroleum, Kuwait University, P.O. Box 5969, Safat 13060 (Kuwait); Krishnan, R. [Center for Rapid Transit Systems, Electrical and Computer Engineering Department, Virginia Tech University, 461 Durham Hall, Blacksburg, VA 24061-011 (United States)

    2010-06-15

    This paper deals with the speed control of switched reluctance motor (SRM) drives taking into account the effects of the mutual inductances between two adjacent phases and the effects of the magnetic saturation of the core. To overcome the problems commonly associated with single-phase excitation, a nonlinear SRM model, which is suitable for two-phase excitation and which takes into account the effects of mutual inductances between two adjacent phases and the magnetic saturation effects, is considered in the design of the proposed controllers. A feedback linearization control scheme and a sliding mode control scheme are designed for this motor drive. The proposed controllers guarantee the convergence of the phase currents and the rotor speed of the motor to their desired values. Simulation results indicate that the proposed controllers work well and that they are robust to changes in the parameters of the system and to changes in the load torque.

  4. Speed control of switched reluctance motors taking into account mutual inductances and magnetic saturation effects

    International Nuclear Information System (INIS)

    Alrifai, M.; Zribi, M.; Rayan, M.; Krishnan, R.

    2010-01-01

    This paper deals with the speed control of switched reluctance motor (SRM) drives taking into account the effects of the mutual inductances between two adjacent phases and the effects of the magnetic saturation of the core. To overcome the problems commonly associated with single-phase excitation, a nonlinear SRM model, which is suitable for two-phase excitation and which takes into account the effects of mutual inductances between two adjacent phases and the magnetic saturation effects, is considered in the design of the proposed controllers. A feedback linearization control scheme and a sliding mode control scheme are designed for this motor drive. The proposed controllers guarantee the convergence of the phase currents and the rotor speed of the motor to their desired values. Simulation results indicate that the proposed controllers work well and that they are robust to changes in the parameters of the system and to changes in the load torque.

  5. Synthesis of high saturation magnetic iron oxide nanomaterials via low temperature hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Bhavani, P.; Rajababu, C.H. [Department of Materials Science & Nanotechnology, Yogivemana University, Vemanapuram 516003, Kadapa (India); Arif, M.D. [Environmental Magnetism Laboratory, Indian Institute of Geomagnetism (IIG), Navi Mumbai 410218, Mumbai (India); Reddy, I. Venkata Subba [Department of Physics, Gitam University, Hyderabad Campus, Rudraram, Medak 502329 (India); Reddy, N. Ramamanohar, E-mail: manoharphd@gmail.com [Department of Materials Science & Nanotechnology, Yogivemana University, Vemanapuram 516003, Kadapa (India)

    2017-03-15

    Iron oxide nanoparticles (IONPs) were synthesized through a simple low temperature hydrothermal approach to obtain with high saturation magnetization properties. Two series of iron precursors (sulfates and chlorides) were used in synthesis process by varying the reaction temperature at a constant pH. The X-ray diffraction pattern indicates the inverse spinel structure of the synthesized IONPs. The Field emission scanning electron microscopy and high resolution transmission electron microscopy studies revealed that the particles prepared using iron sulfate were consisting a mixer of spherical (16–40 nm) and rod (diameter ~20–25 nm, length <100 nm) morphologies that synthesized at 130 °C, while the IONPs synthesized by iron chlorides are found to be well distributed spherical shapes with size range 5–20 nm. On other hand, the IONPs synthesized at reaction temperature of 190 °C has spherical (16–46 nm) morphology in both series. The band gap values of IONPs were calculated from the obtained optical absorption spectra of the samples. The IONPs synthesized using iron sulfate at temperature of 130 °C exhibited high saturation magnetization (M{sub S}) of 103.017 emu/g and low remanant magnetization (M{sub r}) of 0.22 emu/g with coercivity (H{sub c}) of 70.9 Oe{sub ,} which may be attributed to the smaller magnetic domains (d{sub m}) and dead magnetic layer thickness (t). - Highlights: • Comparison of iron oxide materials prepared with Fe{sup +2}/Fe{sup +3} sulfates and chlorides at different temperatures. • We prepared super-paramagnetic and soft ferromagnetic magnetite nanoparticles. • We report higher saturation magnetization with lower coercivity.

  6. Determination of the saturation magnetization, anisotropy field, mean field interaction, and switching field distribution for nanocrystalline hard magnets

    International Nuclear Information System (INIS)

    McCallum, R. William

    2005-01-01

    For a uniaxial nanocrystalline magnetic material, the determination of the saturation magnetization, M s , requires measurements of the magnetization at fields which exceed the anisotropy field. For a typical RE-Tm compound, where RE=rare earth and Tm=transition metal, this may require fields above 7 T if the approach to saturation law is used. However for an isotropic material composed of a random distribution of non-interacting uniaxial grains, both M s and the anisotropy filed, H a , may be determined by fitting the Stoner-Wohlfarth (SW) model (Philos. Trans. Roy. Soc. 240 (1948) 599) to the reversible part of the demagnetization curve in the first quadrant. Furthermore, using the mean field interaction model of Callen, Liu and Cullen [2], a quantitative measure of the interaction strength for interacting particles may be determined. In conjunction with an analytical fit to the first quadrant demagnetization curve of the SW model, this allows M s , H a and the mean field interaction constant of a nanocrystalline magnet to be determined from measurements below 5 T. Furthermore, comparison of the model solution for the reversible magnetization with experimental data in the 2nd and 3rd quadrants allows the accurate determination of the switching field distribution. In many cases the hysteresis loop may be accurately described by a normal distribution of switching fields

  7. Fabrication high-purity Fe nanochains with near theoretical limit value of saturation magnetization of bulk Fe

    Energy Technology Data Exchange (ETDEWEB)

    Bian, Erkang [Henan University, Key Laboratory for Special Functional Materials of Ministry of Education (China); Xu, Yanling [Henan University, The Audit Department (China); Lou, Shiyun, E-mail: lousy@henu.edu.cn [Henan University, Key Laboratory for Special Functional Materials of Ministry of Education (China); Fu, Yunlong, E-mail: yunlongfu@dns.sxnu.edu.cn [Shanxi Normal University, School of Chemistry and Material Science (China); Zhou, Shaomin, E-mail: smzhou@henu.edu.cn [Henan University, Key Laboratory for Special Functional Materials of Ministry of Education (China)

    2016-11-15

    High-yield purity chain-like one-dimensional nanostructures consisting of single crystal Fe nanoparticles have been produced by using solution dispersion approach. Room temperature magnetic measurement shows that the as-fabricated Fe nanochains are ferromagnetic with a high saturation magnetization (203 emu/g) whereas the nanoparticles are single magnetic domains, which indicate that the as-synthesized products have superparamagnetism behavior with the saturation magnetization of about 28 emu/g. Maybe this results from the directional alignment of the nanoparticles. The excellent characteristic may have led to the potential applications in spin filtering, high density magnetic recording, and nanosensors.

  8. Physics of the saturation of particle acceleration in relativistic magnetic reconnection

    Science.gov (United States)

    Kagan, Daniel; Nakar, Ehud; Piran, Tsvi

    2018-05-01

    We investigate the saturation of particle acceleration in relativistic reconnection using two-dimensional particle-in-cell simulations at various magnetizations σ. We find that the particle energy spectrum produced in reconnection quickly saturates as a hard power law that cuts off at γ ≈ 4σ, confirming previous work. Using particle tracing, we find that particle acceleration by the reconnection electric field in X-points determines the shape of the particle energy spectrum. By analysing the current sheet structure, we show that physical cause of saturation is the spontaneous formation of secondary magnetic islands that can disrupt particle acceleration. By comparing the size of acceleration regions to the typical distance between disruptive islands, we show that the maximum Lorentz factor produced in reconnection is γ ≈ 5σ, which is very close to what we find in our particle energy spectra. We also show that the dynamic range in Lorentz factor of the power-law spectrum in reconnection is ≤40. The hardness of the power law combined with its narrow dynamic range implies that relativistic reconnection is capable of producing the hard narrow-band flares observed in the Crab nebula but has difficulty producing the softer broad-band prompt gamma-ray burst emission.

  9. Analysis of saturation effects on the operation of magnetic-controlled switcher type FCL

    Directory of Open Access Journals (Sweden)

    Faramarz Faghihi

    2009-12-01

    Full Text Available With the extensive application of electrical power system, suppression of fault current limiter is an important subject that guarantees system security. The superconducting fault current limiters (SFCL have been expected as a possible type of power apparatus to reduce the fault current in the power system. The results shown that under normal state, the FCL has no obvious effect on the power system; under fault state, the current limiting inductance connected in the bias current will be inserted into the fault circuit to limit the fault current. By regulating the bias current, the FCL voltage loss under normal state and the fault current can be adjusted to prescribed level. This kind of SFCL used the nonlinear permeability of the magnetic core for create a sufficient impedance and The transient performance considering the magnetic saturation is analyzed by Preisach model. Preisach model that intrinsically satisfies nonlinear properties is used as the numerical method for analysis of saturation effects. It is able to identification isotropic and no isotropic behaviour. The main idea is to compute the magnetization vector in two steps independently, amplitude and phase. The described model yield results in qualitative agreement with the experimental results.

  10. Off-resonance artifacts correction with convolution in k-space (ORACLE).

    Science.gov (United States)

    Lin, Wei; Huang, Feng; Simonotto, Enrico; Duensing, George R; Reykowski, Arne

    2012-06-01

    Off-resonance artifacts hinder the wider applicability of echo-planar imaging and non-Cartesian MRI methods such as radial and spiral. In this work, a general and rapid method is proposed for off-resonance artifacts correction based on data convolution in k-space. The acquired k-space is divided into multiple segments based on their acquisition times. Off-resonance-induced artifact within each segment is removed by applying a convolution kernel, which is the Fourier transform of an off-resonance correcting spatial phase modulation term. The field map is determined from the inverse Fourier transform of a basis kernel, which is calibrated from data fitting in k-space. The technique was demonstrated in phantom and in vivo studies for radial, spiral and echo-planar imaging datasets. For radial acquisitions, the proposed method allows the self-calibration of the field map from the imaging data, when an alternating view-angle ordering scheme is used. An additional advantage for off-resonance artifacts correction based on data convolution in k-space is the reusability of convolution kernels to images acquired with the same sequence but different contrasts. Copyright © 2011 Wiley-Liss, Inc.

  11. Nuclear magnetic resonance and sound velocity measurements of chalk saturated with magnesium rich brine

    DEFF Research Database (Denmark)

    Katika, Konstantina; Alam, Mohammad Monzurul; Fabricius, Ida Lykke

    2013-01-01

    The use of low field Nuclear Magnetic Resonance (NMR) to determine petrophysical properties of reservoirs has proved to be a good technique. Together with sonic and electrical resistivity measurements, NMR can contribute to illustrate the changes on chalk elasticity due to different pore water...... solutions of the same ionic strength. Saturation with a solution that contained divalent ions caused a major shift on the distribution of the relaxation time. The changes were probably due to precipitats forming extra internal surface in the sample. Sonic velocities were relatively low in the MgCl2 solution...

  12. Use of nuclear magnetic resonance of hydrogen in the characterization of saturated hydrocarbonic chains

    International Nuclear Information System (INIS)

    Costa Neto, A.; Soares, V.L.P.; Costa Neto, C.

    1979-01-01

    Alkanes and cycloalkanes are characterized by a methyl-methylene-methine groups proportion, the percentual absorption in prefixed regions and the pattern of the spectrum of nuclear magnetic resonance of hydrogen. The GPI is calculated from the contribution of the areas corresponding to prefixed regions of the hydrogen magnetic resonance spectra (60 Mc). These regions are (for the saturated hydrocarbons): 0,5-1,05ppm (X), 1,05ppm (Y) and 1,50-2,00ppm (Z). The validity of the index was verified for the homologous series of linear hydrocarbons and methyl-, dimethyl-, ethyl-, cyclopentyl- and cyclohexyl-branched hydrocarbons. Its application to shale oil chemistry (xistoquimica) is discussed. (author) [pt

  13. A general electromagnetic excitation model for electrical machines considering the magnetic saturation and rub impact

    Science.gov (United States)

    Xu, Xueping; Han, Qinkai; Chu, Fulei

    2018-03-01

    The electromagnetic vibration of electrical machines with an eccentric rotor has been extensively investigated. However, magnetic saturation was often neglected. Moreover, the rub impact between the rotor and stator is inevitable when the amplitude of the rotor vibration exceeds the air-gap. This paper aims to propose a general electromagnetic excitation model for electrical machines. First, a general model which takes the magnetic saturation and rub impact into consideration is proposed and validated by the finite element method and reference. The dynamic equations of a Jeffcott rotor system with electromagnetic excitation and mass imbalance are presented. Then, the effects of pole-pair number and rubbing parameters on vibration amplitude are studied and approaches restraining the amplitude are put forward. Finally, the influences of mass eccentricity, resultant magnetomotive force (MMF), stiffness coefficient, damping coefficient, contact stiffness and friction coefficient on the stability of the rotor system are investigated through the Floquet theory, respectively. The amplitude jumping phenomenon is observed in a synchronous generator for different pole-pair numbers. The changes of design parameters can alter the stability states of the rotor system and the range of parameter values forms the zone of stability, which lays helpful suggestions for the design and application of the electrical machines.

  14. Off-resonant vibrational excitation: Orientational dependence and spatial control of photofragments

    DEFF Research Database (Denmark)

    Machholm, Mette; Henriksen, Niels Engholm

    2000-01-01

    Off-resonant and resonant vibrational excitation with short intense infrared (IR) laser pulses creates localized oscillating wave packets, but differs by the efficiency of the excitation and surprisingly by the orientational dependence. Orientational selectivity of the vibrational excitation...... of randomly oriented heteronuclear diatomic molecules can be obtained under simultaneous irradiation by a resonant and an off-resonant intense IR laser pulse: Molecules with one initial orientation will be vibrationally excited, while those with the opposite orientation will be at rest. The orientation-dependent...... distribution. (C) 2000 American Institute of Physics....

  15. Modelling of a linear PM machine including magnetic saturation and end effects : maximum force to current ratio

    NARCIS (Netherlands)

    Polinder, H.; Slootweg, J.G.; Hoeijmakers, M.J.; Compter, J.C.

    2003-01-01

    The use of linear permanent-magnet (PM) actuators increases in a wide variety of applications because of their high force density, robustness and accuracy. These linear PM motors are often heavily loaded during short intervals of high acceleration, so that magnetic saturation occurs. This paper

  16. Rapid and quantitative chemical exchange saturation transfer (CEST) imaging with magnetic resonance fingerprinting (MRF).

    Science.gov (United States)

    Cohen, Ouri; Huang, Shuning; McMahon, Michael T; Rosen, Matthew S; Farrar, Christian T

    2018-05-13

    To develop a fast magnetic resonance fingerprinting (MRF) method for quantitative chemical exchange saturation transfer (CEST) imaging. We implemented a CEST-MRF method to quantify the chemical exchange rate and volume fraction of the N α -amine protons of L-arginine (L-Arg) phantoms and the amide and semi-solid exchangeable protons of in vivo rat brain tissue. L-Arg phantoms were made with different concentrations (25-100 mM) and pH (pH 4-6). The MRF acquisition schedule varied the saturation power randomly for 30 iterations (phantom: 0-6 μT; in vivo: 0-4 μT) with a total acquisition time of ≤2 min. The signal trajectories were pattern-matched to a large dictionary of signal trajectories simulated using the Bloch-McConnell equations for different combinations of exchange rate, exchangeable proton volume fraction, and water T 1 and T 2 relaxation times. The chemical exchange rates of the N α -amine protons of L-Arg were significantly (P exchange using saturation power method. Similarly, the L-Arg concentrations determined using MRF were significantly (P exchange rate was well fit (R 2  = 0.9186) by a base catalyzed exchange model. The amide proton exchange rate measured in rat brain cortex (34.8 ± 11.7 Hz) was in good agreement with that measured previously with the water exchange spectroscopy method (28.6 ± 7.4 Hz). The semi-solid proton volume fraction was elevated in white (12.2 ± 1.7%) compared to gray (8.1 ± 1.1%) matter brain regions in agreement with previous magnetization transfer studies. CEST-MRF provides a method for fast, quantitative CEST imaging. © 2018 International Society for Magnetic Resonance in Medicine.

  17. Off-resonance plasmonic enhanced femtosecond laser optoporation and transfection of cancer cells.

    Science.gov (United States)

    Baumgart, Judith; Humbert, Laure; Boulais, Étienne; Lachaine, Rémi; Lebrun, Jean-Jaques; Meunier, Michel

    2012-03-01

    A femtosecond laser based transfection method using off-resonance plasmonic gold nanoparticles is described. For human cancer melanoma cells, the treatment leads to a very high perforation rate of 70%, transfection efficiency three times higher than for conventional lipofection, and very low toxicity (transfection for skin cancer treatment. Copyright © 2011 Elsevier Ltd. All rights reserved.

  18. Nonlinear saturated states of the magnetic-curvature-driven Rayleigh-Taylor instability in three dimensions

    International Nuclear Information System (INIS)

    Das, Amita; Sen, Abhijit; Kaw, Predhiman; Benkadda, S.; Beyer, Peter

    2005-01-01

    Three-dimensional electromagnetic fluid simulations of the magnetic-curvature-driven Rayleigh-Taylor instability are presented. Issues related to the existence of nonlinear saturated states and the nature of the temporal evolution to such states from random initial conditions are addressed. It is found that nonlinear saturated states arising from generation of zonal shear flows continue to exist in certain parametric domains but their spectrum and spatial characteristics have important differences from earlier two-dimensional results reported in Phys. Plasmas 4, 1018 (1997) and Phys. Plasmas 8, 5104 (2001). In particular, the three-dimensional nonlinear states possess a significant power level in short scales and the spatial structures of the potential and density fluctuations appear not to develop any functional correlations. Electromagnetic effects are found to inhibit the formation of zonal flows and thereby to considerably restrict the parametric domain of nonlinear stabilization. The role of finite k parallel and the contribution of the unstable drift wave branch are also discussed and delineated through a number of simulation studies carried out in special simplified limits

  19. Anti-saturation system for surface nuclear magnetic resonance in efficient groundwater detection

    Science.gov (United States)

    Lin, Jun; Zhang, Yang; Yang, Yujing; Sun, Yong; Lin, Tingting

    2017-06-01

    Compared to other geophysical techniques, the surface nuclear magnetic resonance (SNMR) method could provide unique insights into the hydrologic properties of groundwater in the subsurface. However, the SNMR signal is in the order of nanovolts (10-9 V), and the complex environmental noise, i.e., the spike and the harmony noise (10-4 V), can reach up to 105 times the signal amplitude. Saturation of the amplifier is therefore a serious problem in current SNMR systems. In this study, we propose an anti-saturation method based on an instantaneous floating-point amplifier. The gain of a programmable amplifier is controlled by the value of the input signal. A regulating speed of 50 kS/s is thus achieved to satisfy the self-adaptive adjustment of the real-time SNMR system, which replaces the original man-made setting gain. A large dynamic range of 192.65 dB with a 24-bit high speed analog-digital converter module is then implemented. Compared to traditional SNMR instruments, whose magnification factor is fixed during the experiment, our system can effectively inhibit the distortion of the SNMR signal in both laboratory and field settings. Furthermore, an improved SNR, which is realized by the real-time SNMR system, enables the accurate inversion of the aquifer. Our study broadens the applicability of SNMR systems to use in and around developed areas.

  20. Velocity Regulation in Switched Reluctance Motors under Magnetic Flux Saturation Conditions

    Directory of Open Access Journals (Sweden)

    Victor M. Hernández-Guzmán

    2018-01-01

    Full Text Available We propose a controller for velocity regulation in switched reluctance motors under magnetic flux saturation conditions. Both hysteresis and proportional control are employed in the internal electric current loops. A classical PI velocity controller is employed in the external loop. Our control law is the simplest one proposed in the literature but provided with a formal stability proof. We prove that the state is bounded having an ultimate bound which can be rendered arbitrarily small by a suitable selection of controller gains. Furthermore, this result stands when starting from any initial condition within a radius which can be arbitrarily enlarged using suitable controller gains. We present a simulation study where even convergence to zero of velocity error is observed as well as a good performance when regulating velocity in the presence of unknown step changes in external torque disturbances.

  1. Influence of magnetic saturation effects on the fault detection of induction motors

    Directory of Open Access Journals (Sweden)

    Drozdowski Piotr

    2014-09-01

    Full Text Available In this paper, the influence of impact damage to the induction motors on the zero-sequence voltage and its spectrum is presented. The signals detecting the damages result from a detailed analysis of the formula describing this voltage component which is induced in the stator windings due to core magnetic saturation and the discrete displacement of windings. Its course is affected by the operation of both the stator and the rotor. Other fault detection methods, are known and widely applied by analysing the spectrum of stator currents. The presented method may be a complement to other methods because of the ease of measurements of the zero voltage for star connected motors. Additionally, for converter fed motors the zero sequence voltage eliminates higher time harmonics displaced by 120 degrees. The results of the method application are presented through measurements and explained by the use of a mathematical model of the slip-ring induction motor

  2. Eddy-current inspection of ferromagnetic tubing using pulsed magnetic saturation

    Energy Technology Data Exchange (ETDEWEB)

    Dodd, C V; Deeds, W E

    1986-07-01

    A pulsed eddy-current system has been designed and developed for nondestructive evaluation of 2.25Cr-1Mo steam generator tubing from the bore side. Since the tubing is ferromagnetic, a large current pulse is sent through a driver coil to produce magnetic saturation all the way through the tube wall. A pickup coil produces an output pulse that is dependent upon the tube properties as well as the driving pulse. The output pulse heights at selected times are used as data that are computer-correlated with calibration data taken from machined standards. Performance data, circuit diagrams, and computer programs are given for the system, which has been demonstrated to detect small flaws located near the outside of a thick ferromagnetic tube.

  3. Modeling of the Direct Current Generator Including the Magnetic Saturation and Temperature Effects

    Directory of Open Access Journals (Sweden)

    Alfonso J. Mercado-Samur

    2013-11-01

    Full Text Available In this paper the inclusion of temperature effect on the field resistance on the direct current generator model DC1A, which is valid to stability studies is proposed. First, the linear generator model is presented, after the effect of magnetic saturation and the change in the resistance value due to temperature produced by the field current are included. The comparison of experimental results and model simulations to validate the model is used. A direct current generator model which is a better representation of the generator is obtained. Visual comparison between simulations and experimental results shows the success of the proposed model, because it presents the lowest error of the compared models. The accuracy of the proposed model is observed via Modified Normalized Sum of Squared Errors index equal to 3.8979%.

  4. Minor-Cu doped soft magnetic Fe-based FeCoBCSiCu amorphous alloys with high saturation magnetization

    Science.gov (United States)

    Li, Yanhui; Wang, Zhenmin; Zhang, Wei

    2018-05-01

    The effects of Cu alloying on the amorphous-forming ability (AFA) and magnetic properties of the P-free Fe81Co5B11C2Si1 amorphous alloy were investigated. Addition of ≤ 1.0 at.% Cu enhances the AFA of the base alloy without significant deterioration of the soft magnetic properties. The Fe80.5Co5B11C2Si1Cu0.5 alloy with the largest critical thickness for amorphous formation of ˜35 μm possesses a high saturation magnetization (Bs) of ˜1.78 T, low coercivity of ˜14.6 A/m, and good bending ductility upon annealing in a wide temperature range of 513-553 K with maintaining the amorphous state. The fabrication of the new high-Fe-content Fe-Co-B-C-Si-Cu amorphous alloys by minor doping of Cu gives a guideline to developing high Bs amorphous alloys with excellent AFA.

  5. ANALYSIS OF THE SPECIAL FEATURES OF THE THERMAL PROCESS IN AN INDUCTION GENERATOR AT HIGH SATURATION OF THE MAGNETIC SYSTEM

    Directory of Open Access Journals (Sweden)

    V. Chenchevoi

    2017-06-01

    Full Text Available Purpose. Development of the method for the assessment of the thermal operation modes of an autonomous electrical power system with an induction motor, aiming at improvement of the reliability of electricity supply and the quality of electric energy. Methodology. Induction generator mathematical modeling taking into account the magnetic system saturation was used in the research. A heat model taking into account the excess of the temperature of the induction generator units in the mode of high saturation was developed. The obtained results were compared with the experimental data. Results. The paper contains the solution to the problem of improvement of the mathematical model sand methods for steel losses determination in there search of the operation modes of an autonomous uncontrolled induction generator taking into consideration the properties of the magnetic system in the mode of high saturation. The expression for determination of steel losses in the mode of high saturation is obtained. It enables the assessment of the induction generator thermal condition. Originality. The analytical dependence for the calculation of the steel losses in the mode of magnetic system saturation has been obtained for the first time. Practical value. The obtained expression for the calculation of the steel losses can be used for determination of the admissible time of generator operation at overload. It will allow avoiding broken winding insulation and complete use of the generator overload capacity. As a result, it will reduce possible irregularities of electricity supply due to the generator preliminary cutoff.

  6. Use of an elliptical aperture to control saturation in closely-coupled, cold iron, superconducting dipole magnets

    International Nuclear Information System (INIS)

    Morgan, G.

    1985-01-01

    The high fields permitted by superconducting windings result in saturation of closely-coupled iron in dipole and quadrupole beam transport magnets. Coupland suggested using a triangular cutout at the poles to reduce the change in the sextupole (b 2 ) term due to saturation. The use of an elliptical aperture in a close-coupled dipole for the Relativistic Heavy Ion Collider (RHIC) has been studied using the BNL computer program MDP (a version of GFUN). The ellipse aspect ratio was varied while holding the horizontal (minor) radius constant. The proper aspect ratio gives no shift in b 2 sue to saturation, and a reduction in the b 4 shift. A modification of the ellipse also reduces b 4 . The elliptical aperture introduces a large b 2 term at low field which must be compensated for by the coil design. A practical coil design which does this for the RHIC magnet is presented. 5 refs., 2 figs., 3 tabs

  7. Explanation of the quantum phenomenon of off-resonant cavity-mode emission

    Science.gov (United States)

    Echeverri-Arteaga, Santiago; Vinck-Posada, Herbert; Gómez, Edgar A.

    2018-04-01

    We theoretically investigate the unexpected occurrence of an extra emission peak that has been experimentally observed in off-resonant studies of cavity QED systems. Our results within the Markovian master equation approach successfully explain why the central peak arises, and how it reveals that the system is suffering a dynamical phase transition induced by the phonon-mediated coupling. Our findings are in qualitative agreement with previous reported experimental results, and the fundamental physics behind this quantum phenomenon is understood.

  8. Kerr-like behaviour of second harmonic generation in the far-off resonant regime

    Science.gov (United States)

    Peřinová, Vlasta; Lukš, Antonín; Křepelka, Jaromír; Leoński, Wiesław; Peřina, Jan

    2018-05-01

    We separate the Kerr-like behaviour of the second-harmonic generation in the far-off resonant regime from the oscillations caused by the time-dependence of the interaction energy. To this purpose, we consider the approximation obtained from the exact dynamics by the method of small rotations. The Floquet-type decomposition of the approximate dynamics comprises the Kerr-like dynamics and oscillations of the same order of magnitude as those assumed for the exact dynamics of the second-harmonic generation. We have found that a superposition of two states of concentrated quantum phase arises in the fundamental mode in the second-harmonic generation in the far-off resonant limit at a later time than a superposition of two coherent states in the corresponding Kerr medium and the difference is larger for higher initial coherent amplitudes. The quantum phase fluctuation is higher for the same initial coherent amplitudes in the fundamental mode in the second-harmonic generation in the far-off resonant limit than in the corresponding Kerr medium and the difference is larger for higher initial coherent amplitudes.

  9. Nuclear Magnetic Resonance and Elastic Wave Velocity of Chalk Saturated with Brines Containing Divalent Ions

    DEFF Research Database (Denmark)

    Katika, Konstantina; Alam, Mohammad Monzurul; Fabricius, Ida Lykke

    divided into groups of three and each group was saturated either with deionized water, calcite equilibrated water, or sodium chloride, magnesium chloride and calcium chloride solutions of the same ionic strength. Saturation with solutions that contain divalent ions caused major shifts in the distribution...... of the relaxation time. Core samples saturated with calcium chloride solution relaxed slower and those saturated with magnesium chloride solution relaxed faster than the rest of the samples. Along with the changes in relaxation the samples experienced smaller velocities of elastic waves when saturated with MgCl2...

  10. Thermal treatment to enhance saturation magnetization of superparamagnetic Ni nanoparticles while maintaining low coercive force

    Science.gov (United States)

    Ishizaki, Toshitaka; Yatsugi, Kenichi; Akedo, Kunio

    2018-05-01

    Superparamagnetic nanoparticles capped by insulators have the potential to decrease eddy current and hysteresis losses. However, the saturation magnetization ( M s) decreases significantly with decreasing the particle size. In this study, superparamagnetic Ni nanoparticles having the mean size of 11.6 ± 1.8 nm were synthesized from the reduction of Ni(II) acetylacetonate in oleylamine with the addition of trioctylphosphine, indicating the coercive force ( H c) less than 1 Oe. Thermal treatments of the Ni nanoparticles were investigated as a method to enhance the M s. The results indicated that the M s was enhanced by an increase of the Ni mass ratio with increasing thermal treatment temperature. However, the decomposition behavior of the capping layers indicated that their alkyl chains actively decomposed at temperatures above 523 K to form Ni3P via reaction between Ni and P, resulting in particle growth with a significant increase in the H c. Therefore, the optimal temperature was determined to be 473 K, which increased the Ni ratio without formation of Ni3P while maintaining particle sizes with superparamagnetic properties. Further, the M s could be improved by 22% (relative to the as-synthesized Ni nanoparticles) after thermal treatment at 473 K while maintaining the H c to be less than 1 Oe.

  11. Towards measuring the off-resonant thermal noise of a pendulum mirror

    CERN Document Server

    Leonhardt, V; Kloevekorn, P; Willke, B; Lück, H B; Danzmann, K

    2002-01-01

    Thermal noise is one of the dominant noise sources in interferometric length measurements and can limit the sensitivity of gravitational wave detectors. Our goal is to analyse the off-resonant thermal noise of a high Q pendulum. Therefore we interferometrically detect the length changes of a 2.3 cm long optical resonator, which for good seismic isolation consists of two multiple stage pendulums. We are able to lock the length of this optical resonator to a frequency-stabilized laser beam and as a result get the spectral density of the differential mirror movement.

  12. Off-resonance transformer charging for 250-kV water Blumlein

    International Nuclear Information System (INIS)

    Cook, E.; Reginato, L.

    1978-01-01

    An off-resonance transformer for charging a 250-kV Blumlein system provides a viable alternative to other charging schemes by permitting the use of conventional thyratrons. Such a transformer must have reliability, a reasonable voltage step-up, and a non-reversing primary current. The analysis, design, and performance data for such a transformer are presented. The strong interrelationship between transformer design and Blumlein requirements necessitates that Blumlein description and design criterion be briefly presented prior to transformer design such that transformer load requirements be defined

  13. Rapidly reconfigurable slow-light system based on off-resonant Raman absorption

    International Nuclear Information System (INIS)

    Vudyasetu, Praveen K.; Howell, John C.; Camacho, Ryan M.

    2010-01-01

    We present a slow-light system based on dual Raman absorption resonances in warm rubidium vapor. Each Raman absorption resonance is produced by a control beam in an off-resonant Λ system. This system combines all optical control of the Raman absorption and the low-dispersion broadening properties of the double Lorentzian absorption slow light. The bandwidth, group delay, and central frequency of the slow-light system can all be tuned dynamically by changing the properties of the control beam. We demonstrate multiple pulse delays with low distortion and show that such a system has fast switching dynamics and thus fast reconfiguration rates.

  14. Off-resonance suppression for multispectral MR imaging near metallic implants.

    Science.gov (United States)

    den Harder, J Chiel; van Yperen, Gert H; Blume, Ulrike A; Bos, Clemens

    2015-01-01

    Metal artifact reduction in MRI within clinically feasible scan-times without through-plane aliasing. Existing metal artifact reduction techniques include view angle tilting (VAT), which resolves in-plane distortions, and multispectral imaging (MSI) techniques, such as slice encoding for metal artifact correction (SEMAC) and multi-acquisition with variable resonances image combination (MAVRIC), that further reduce image distortions, but significantly increase scan-time. Scan-time depends on anatomy size and anticipated total spectral content of the signal. Signals outside the anticipated spatial region may cause through-plane back-folding. Off-resonance suppression (ORS), using different gradient amplitudes for excitation and refocusing, is proposed to provide well-defined spatial-spectral selectivity in MSI to allow scan-time reduction and flexibility of scan-orientation. Comparisons of MSI techniques with and without ORS were made in phantom and volunteer experiments. Off-resonance suppressed SEMAC (ORS-SEMAC) and outer-region suppressed MAVRIC (ORS-MAVRIC) required limited through-plane phase encoding steps compared with original MSI. Whereas SEMAC (scan time: 5'46") and MAVRIC (4'12") suffered from through-plane aliasing, ORS-SEMAC and ORS-MAVRIC allowed alias-free imaging in the same scan-times. ORS can be used in MSI to limit the selected spatial-spectral region and contribute to metal artifact reduction in clinically feasible scan-times while avoiding slice aliasing. © 2014 Wiley Periodicals, Inc.

  15. Imaging in Vivo Extracellular pH with a Single Paramagnetic Chemical Exchange Saturation Transfer Magnetic Resonance Imaging Contrast Agent

    Directory of Open Access Journals (Sweden)

    Guanshu Liu

    2012-01-01

    Full Text Available The measurement of extracellular pH (pHe has potential utility for cancer diagnoses and for assessing the therapeutic effects of pH-dependent therapies. A single magnetic resonance imaging (MRI contrast agent that is detected through paramagnetic chemical exchange saturation transfer (PARACEST was designed to measure tumor pHe throughout the range of physiologic pH and with magnetic resonance saturation powers that are not harmful to a mouse model of cancer. The chemical characterization and modeling of the contrast agent Yb3+-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid, 10-o-aminoanilide (Yb-DO3A-oAA suggested that the aryl amine of the agent forms an intramolecular hydrogen bond with a proximal carboxylate ligand, which was essential for generating a practical chemical exchange saturation transfer (CEST effect from an amine. A ratio of CEST effects from the aryl amine and amide was linearly correlated with pH throughout the physiologic pH range. The pH calibration was used to produce a parametric pH map of a subcutaneous flank tumor on a mouse model of MCF-7 mammary carcinoma. Although refinements in the in vivo CEST MRI methodology may improve the accuracy of pHe measurements, this study demonstrated that the PARACEST contrast agent can be used to generate parametric pH maps of in vivo tumors with saturation power levels that are not harmful to a mouse model of cancer.

  16. Comments on ''The non-linear saturation of a magnetic island'' by J. Norris

    International Nuclear Information System (INIS)

    Thyagaraja, A.

    1990-01-01

    Recent results derived on non-linear saturation of tearing modes (Norris, J., Plasma Phys. Contr. Fusion, 1989, Vol. 31, 699) are examined in relation to previously published literature. It is explicitly demonstrated that they are at variance in several important respects with those due to previous workers in this area. (author)

  17. Off-resonant transitions in the collective dynamics of multi-level atomic ensembles

    DEFF Research Database (Denmark)

    Miroshnychenko, Yevhen; Mølmer, Klaus

    2013-01-01

    We study the contributions of off-resonant transitions to the dynamics of a system of N multi-level atoms sharing one excitation and interacting with the quantized vector electromagnetic field. The rotating wave approximation significantly simplifies the derivation of the equations of motion...... describing the collective atomic dynamics, but it leads to an incorrect expression for the dispersive part of the atom–atom interaction terms. For the case of two-level atoms and a scalar electromagnetic field, it turns out that the atom–atom interaction can be recovered correctly if integrals over...... the photon mode frequencies are extended to incorporate negative values. We explicitly derive the atom–atom interaction for multi-level atoms, coupled to the full vector electromagnetic field, and we recover also in this general case the validity of the results obtained by the extension to negative...

  18. On- and off-resonance radiation-atom-coupling matrix elements involving extended atomic wave functions

    Science.gov (United States)

    Komninos, Yannis; Mercouris, Theodoros; Nicolaides, Cleanthes A.

    2014-01-01

    In continuation of our earlier works, we present results concerning the computation of matrix elements of the multipolar Hamiltonian (MPH) between extended wave functions that are obtained numerically. The choice of the MPH is discussed in connection with the broader issue of the form of radiation-atom (or -molecule) interaction that is appropriate for the systematic solution of various problems of matter-radiation interaction. We derive analytic formulas, in terms of the sine-integral function and spherical Bessel functions of various orders, for the cumulative radial integrals that were obtained and calculated by Komninos, Mercouris, and Nicolaides [Phys. Rev. A 71, 023410 (2005), 10.1103/PhysRevA.71.023410]. This development allows the much faster and more accurate computation of such matrix elements, a fact that enhances the efficiency with which the time-dependent Schrödinger equation is solved nonperturbatively, in the framework of the state-specific expansion approach. The formulas are applicable to the general case where a pair of orbitals with angular parts |ℓ1,m1> and |ℓ2,m2> are coupled radiatively. As a test case, we calculate the matrix elements of the electric field and of the paramagnetic operators for on- and off-resonance transitions, between hydrogenic circular states of high angular momentum, whose quantum numbers are chosen so as to satisfy electric dipole and electric quadrupole selection rules. Because of the nature of their wave function (they are nodeless and the large centrifugal barrier keeps their overwhelming part at large distances from the nucleus), the validity of the electric dipole approximation in various applications where the off-resonance couplings must be considered becomes precarious. For example, for the transition from the circular state with n = 20 to that with n = 21, for which ≈400 a.u., the dipole approximation starts to fail already at XUV wavelengths (λ <125nm).

  19. Detection of Static Eccentricity Fault in Saturated Induction Motors by Air-Gap Magnetic Flux Signature Analysis Using Finite Element Method

    Directory of Open Access Journals (Sweden)

    N. Halem

    2013-06-01

    Full Text Available Unfortunately, motor current signature analysis (MCSA cannot detect the small degrees of the purely static eccentricity (SE defects, while the air-gap magnetic flux signature analysis (FSA is applied successfully. The simulation results are obtained by using time stepping finite elements (TSFE method. In order to show the impact of magnetic saturation upon the diagnosis of SE fault, the analysis is carried out for saturated induction motors. The index signatures of static eccentricity fault around fundamental and PSHs are detected successfully for saturated motor.

  20. DETECTION OF STATIC ECCENTRICITY FAULT IN SATURATED INDUCTION MOTORS BY AIR-GAP MAGNETIC FLUX SIGNATURE ANALYSIS USING FINITE ELEMENT METHOD

    Directory of Open Access Journals (Sweden)

    N. Halem

    2013-06-01

    Full Text Available Unfortunately, motor current signature analysis (MCSA cannot detect the small degrees of the purely static eccentricity (SE defects, while the air-gap magnetic flux signature analysis (FSA is applied successfully. The simulation results are obtained by using time stepping finite elements (TSFE method. In order to show the impact of magnetic saturation upon the diagnosis of SE fault, the analysis is carried out for saturated induction motors. The index signatures of static eccentricity fault around fundamental and PSHs are detected successfully for saturated motor.

  1. DETECTION OF STATIC ECCENTRICITY FAULT IN SATURATED INDUCTION MOTORS BY AIR-GAP MAGNETIC FLUX SIGNATURE ANALYSIS USING FINITE ELEMENT METHOD

    Directory of Open Access Journals (Sweden)

    N. Halem

    2015-07-01

    Full Text Available Unfortunately, motor current signature analysis (MCSA cannot detect the small degrees of the purely static eccentricity (SE defects, while the air-gap magnetic flux signature analysis (FSA is applied successfully. The simulation results are obtained by using time stepping finite elements (TSFE method. In order to show the impact of magnetic saturation upon the diagnosis of SE fault, the analysis is carried out for saturated induction motors. The index signatures of static eccentricity fault around fundamental and PSHs are detected successfully for saturated motor.

  2. Upper limit for the effect of elastic bending stress on the saturation magnetization of La0.8Sr0.2MnO3

    KAUST Repository

    Wang, Q.

    2018-01-31

    Using polarized neutron reflectometry, we measured the influence of elastic bending stress on the magnetization depth profile of a La0.8Sr0.2MnO3 (LSMO) epitaxial film grown on a SrTiO3 substrate. The elastic bending strain of +/- 0.03% has no obvious effect on the magnetization depth profile at saturation. This result is in stark contrast to that of (La1-xPrx)(1-y),Ca-y,MnO3 (LPCMO) films for which strain of +/- 0.01% produced dramatic changes in the magnetization profile and Curie temperature. We attribute the difference between the influence of strain on the saturation magnetization in LSMO (weak or none) and LPCMO (strong) to a difference in the ability of LSMO (weak or none) and LPCMO (strong) to phase separate. Our observation provides an upper limit of tuning LSMO saturation magnetization via elastic strain effect.

  3. Upper limit for the effect of elastic bending stress on the saturation magnetization of L a0.8S r0.2Mn O3

    Science.gov (United States)

    Wang, Q.; Chen, A. P.; Guo, E. J.; Roldan, M. A.; Jia, Q. X.; Fitzsimmons, M. R.

    2018-01-01

    Using polarized neutron reflectometry, we measured the influence of elastic bending stress on the magnetization depth profile of a L a0.8S r0.2Mn O3 (LSMO) epitaxial film grown on a SrTi O3 substrate. The elastic bending strain of ±0.03 % has no obvious effect on the magnetization depth profile at saturation. This result is in stark contrast to that of (L a1 -xP rx)1 -y C ayMn O3 (LPCMO) films for which strain of ±0.01 % produced dramatic changes in the magnetization profile and Curie temperature. We attribute the difference between the influence of strain on the saturation magnetization in LSMO (weak or none) and LPCMO (strong) to a difference in the ability of LSMO (weak or none) and LPCMO (strong) to phase separate. Our observation provides an upper limit of tuning LSMO saturation magnetization via elastic strain effect.

  4. Study of Factors Related to Magnetic Treatment of Calcium Carbonate Saturated Water

    National Research Council Canada - National Science Library

    Lambert, Kevin

    1998-01-01

    ..., calcium carbonate concentration and number of magnetic device attached. XRD of crystals gave relative proportions of calcite and aragonite present and XRF measured transition metals and elements known to substitute for calcium in scale...

  5. Amendment of saturation magnetization, blocking temperature and particle size homogeneity in Mn-ferrite nanoparticles using Co-Zn substitution

    Energy Technology Data Exchange (ETDEWEB)

    Eltabey, M.M. [Basic Engineering Science Department, Faculty of Engineering, Menoufiya University (Egypt); Physics Department, Faculty of Science, Jazan University, Jazan (Saudi Arabia); Massoud, A.M., E-mail: Amassouda1@yahoo.com [Physics Department, Faculty of Science, Ain Shams University, Abbassia 11566, Cairo (Egypt); Radu, Cosmin [Lake Shore Cryotronics, Inc., Westerville, OH (United States)

    2017-01-15

    Nanocrystalline particles of compositions (CoZn){sub x}Mn{sub 1−x}Fe{sub 2}O{sub 4} were prepared by the coprecipitation method from stoichiometric aqueous solutions, where x varies from 0 to 0.3 in steps of 0.05. The synthesized powders were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and Fourier transform infrared spectroscopy (FT-IR). A vibrating sample magnetometer (VSM) was used to measure the hysteresis parameters at 300 and 6 K. Zero field cooling (ZFC) and field cooling (FC) curves were obtained at the temperature range 6–400 K and the blocking temperature values were determined. XRD analysis confirmed the formation of the obtained powder in a single cubic spinel phase and it showed also that the lattice parameter is decreasing with the increase of (Co-Zn) content. FT-IR measurements between 160 and 650 cm{sup −1} also confirmed the intrinsic cation vibrations of the spinel structure. The magnetic measurements showed that the saturation magnetization, coercivity and the values of blocking temperatures were increased with the (Co-Zn) content. TEM micrographs declared the improvement of particle size homogeneity with the increase of (Co-Zn) content without remarkable change in the average particle size. The obtained results were discussed in view of A-B sublattices interaction and superparamagnetic phenomenon. - Highlights: • Nanocrystalline particles of compositions (CoZn){sub x}Mn{sub 1-x}Fe{sub 2}O{sub 4} were prepared by the coprecipitation method. • XRD analysis showed that the lattice parameter is decreased with the increase of (Co,Zn) content. • The saturation magnetization is improved with the (Co,Zn) content. • Particle size homogeneity is enhanced with (Co,Zn) content. • The values of blocking temperatures are enhanced with increasing (Co,Zn) content.

  6. Nuclear magnetic resonance characterization of the stationary dynamics of partially saturated media during steady-state infiltration flow

    Science.gov (United States)

    Rassi, Erik M.; Codd, Sarah L.; Seymour, Joseph D.

    2011-01-01

    Flow in porous media and the resultant hydrodynamics are important in fields including but not limited to the hydrology, chemical, medical and petroleum industries. The observation and understanding of the hydrodynamics in porous media are critical to the design and optimal utilization of porous media, such as those seen in trickle-bed reactors, medical filters, subsurface flows and carbon sequestration. Magnetic resonance (MR) provides for a non-invasive technique that can probe the hydrodynamics on pore and bulk scale lengths; many previous works have characterized fully saturated porous media, while rapid MR imaging (MRI) methods in particular have previously been applied to partially saturated flows. We present time- and ensemble-averaged MR measurements to observe the effects on a bead pack partially saturated with air under flowing water conditions. The 10 mm internal diameter bead pack was filled with 100 μm borosilicate glass beads. Air was injected into the bead pack as water flowed simultaneously through the sample at 25 ml h-1. The initial partially saturated state was characterized with MRI density maps, free induction decay (FID) experiments, propagators and velocity maps before the water flow rate was increased incrementally from 25 to 500 ml h-1. After the maximum flow rate of 500 ml h-1, the MRI density maps, FID experiments, propagators and velocity maps were repeated and compared to the data taken before the maximum flow rate. This work shows that a partially saturated single-phase flow has global flow dynamics that return to characteristic flow statistics once a steady-state high flow rate has been reached. This high flow rate pushed out a significant amount of the air in the bead pack and caused the return of a preferential flow pattern. Velocity maps indicated that local flow statistics were not the same for the before and after blow out conditions. It has been suggested and shown previously that a flow pattern can return to

  7. Nuclear magnetic resonance characterization of the stationary dynamics of partially saturated media during steady-state infiltration flow

    International Nuclear Information System (INIS)

    Rassi, Erik M; Codd, Sarah L; Seymour, Joseph D

    2011-01-01

    Flow in porous media and the resultant hydrodynamics are important in fields including but not limited to the hydrology, chemical, medical and petroleum industries. The observation and understanding of the hydrodynamics in porous media are critical to the design and optimal utilization of porous media, such as those seen in trickle-bed reactors, medical filters, subsurface flows and carbon sequestration. Magnetic resonance (MR) provides for a non-invasive technique that can probe the hydrodynamics on pore and bulk scale lengths; many previous works have characterized fully saturated porous media, while rapid MR imaging (MRI) methods in particular have previously been applied to partially saturated flows. We present time- and ensemble-averaged MR measurements to observe the effects on a bead pack partially saturated with air under flowing water conditions. The 10 mm internal diameter bead pack was filled with 100 μm borosilicate glass beads. Air was injected into the bead pack as water flowed simultaneously through the sample at 25 ml h -1 . The initial partially saturated state was characterized with MRI density maps, free induction decay (FID) experiments, propagators and velocity maps before the water flow rate was increased incrementally from 25 to 500 ml h -1 . After the maximum flow rate of 500 ml h -1 , the MRI density maps, FID experiments, propagators and velocity maps were repeated and compared to the data taken before the maximum flow rate. This work shows that a partially saturated single-phase flow has global flow dynamics that return to characteristic flow statistics once a steady-state high flow rate has been reached. This high flow rate pushed out a significant amount of the air in the bead pack and caused the return of a preferential flow pattern. Velocity maps indicated that local flow statistics were not the same for the before and after blow out conditions. It has been suggested and shown previously that a flow pattern can return to similar

  8. Half Size Reduction of DC Output Filter Inductors With the Saturation-Gap Magnetic Bias Topology

    DEFF Research Database (Denmark)

    Aguilar, Andres Revilla; Munk-Nielsen, Stig

    2016-01-01

    Filter inductors are probably one of the heaviest and more voluminous components found in power supplies of most electronic devices. A known technique to reduce the inductor size in dc applications is the use of permanent magnet inductors (PMIs). One of the latest developed biasing topologies...

  9. Far off-resonance laser frequency stabilization using multipass cells in Faraday rotation spectroscopy.

    Science.gov (United States)

    Quan, Wei; Li, Yang; Li, Rujie; Shang, Huining; Fang, Zishan; Qin, Jie; Wan, Shuangai

    2016-04-01

    We propose a far off-resonance laser frequency stabilization method by using multipass cells in Rb Faraday rotation spectroscopy. Based on the detuning equation, if multipass cells with several meters optical path length are used in the conventional Faraday spectroscopy, the detuning of the lock point can be extended much further from the alkali metal resonance. A plate beam splitter was used to generate two different Faraday signals at the same time. The transmitted optical path length was L=50  mm and the reflected optical path length was 2L=100  mm. When the optical path length doubled, the detuning of the lock points moved further away from the atomic resonance. The temperature dependence of the detuning of the lock point was also analyzed. A temperature-insensitive lock point was found near resonance when the cell temperature was between 110°C and 130°C. We achieved an rms fluctuation of 0.9 MHz/23 h at a detuning of 0.5 GHz. A frequency drift of 16 MHz/h at a detuning of -5.6  GHz and 4 MHz/h at a detuning of -5.2  GHz were also obtained for the transmitted and reflected light Faraday signal.

  10. Magnetic Resonance Imaging in degenerative disease of the lumbar spine: Fat Saturation technique and contrast medium.

    Science.gov (United States)

    D'Aprile, Paola; Nasuto, Michelangelo; Tarantino, Alfredo; Cornacchia, Samantha; Guglielmi, Giuseppe; Jinkins, J Randy

    2018-01-19

    To examine both anterior and posterior elements of the lumbar spine in patients with low back pain using MRI T2-weighted sequences with Fat Saturation (FS) and contrast enhanced T1-weighted sequences with FS. Two thousand eight hundred and twenty (2820) patients (1628 male, 1192 female, mean age 54) presenting low back pain underwent MRI standard examination (Sagittal T1w TSE and T2w TSE, axial T1 SE) with the addition of sagittal and axial T2w Fat Sat (FS) sequences. Among all the patients, 987 (35%) have been studied adding Contrast Enhanced (CE) T1w FS sequences after administration of contrast medium. Among 987 patients studied with contrast medium, we found: active-inflammatory intervertebral osteochondrosis in 646 (65%) patients; degenerative-inflammatory changes in facet joints (facet joint effusion, synovitis, synovial cysts) in 462 (47%); spondylolysis in 69 (7%); degenerative-inflammatory changes of the flava, interspinous and supraspinous ligaments in 245 (25%); inflammatory changes of posterior perispinal muscles in 84 (8%) patients. In patients with suspected no-disc-related low back pain, the implementation of T2w FS and CE T1w FS sequences to the standard MR protocol could allow a better identification of degenerative-inflammatory changes more likely associated to the pain.

  11. μ+-meson method of investigation of monocrystalline samples of ferromagnetic metals magnetized to saturation

    International Nuclear Information System (INIS)

    Gorelkin, V.N.; Miloserdin, V.Yu.; Smilga, V.P.

    1977-01-01

    Analysis and calculation have been performed with respect to local magnetic fields in nickel, cobalt and iron lattices with the use of the Ehwald's method. Based on the calculation results regularities have been established of the behaviour of muons in the given ferromagnetic materials in the absence of muon diffusion. It has been found that the μ + meson method makes it possible to study the position of a hydrogen light isotope (muonium) in the metal crystal lattice, deformation and stressed state of the lattice, to measure the contact and dipole fields. The advantages of the μ + meson method in the study of ferromagnetic properties are shown

  12. Saturation of VCMA in out-of-plane magnetized CoFeB/MgO/CoFeB magnetic tunnel junctions

    Science.gov (United States)

    Williamson, M.; de Rozieres, M.; Almasi, H.; Chao, X.; Wang, W.; Wang, J.-P.; Tsoi, M.

    2018-05-01

    Voltage controlled magnetic anisotropy (VCMA) currently attracts considerable attention as a novel method to control and manipulate magnetic moments in high-speed and low-power spintronic applications based on magnetic tunnel junctions (MTJs). In our experiments, we use ferromagnetic resonance (FMR) to study and quantify VCMA in out-of-plane magnetized CoFeB/MgO/CoFeB MTJ pillars. FMR is excited by applying a microwave current and detected via a small rectified voltage which develops across MTJ at resonance. The VCMA effective field can be extracted from the measured resonance field and was found to vary as a function of electrical bias applied to MTJ. At low applied biases, we observe a linear shift of the VCMA field as a function of the applied voltage which is consistent with the VCMA picture based on the bias-induced electron migration across the MgO/CoFeB interface. At higher biases, both positive and negative, we observe a deviation from the linear behavior which may indicate a saturation of the VCMA effect. These results are important for the design of MTJ-based applications.

  13. Significant reduction of saturation magnetization and microwave-reflection loss in barium-natural ferrite via Nd3+ substitution

    Science.gov (United States)

    Widanarto, W.; Ardenti, E.; Ghoshal, S. K.; Kurniawan, C.; Effendi, M.; Cahyanto, W. T.

    2018-06-01

    To minimize the signal degradation, many electronic devices require efficient microwave absorbers with very low reflection-losses within the X-band. We prepared a series of trivalent neodymium-ion (Nd3+) substituted barium-natural ferrite using a modified solid-state reaction method. The effect of the Nd3+-ion content on the structure, surface morphology, magnetic properties, and microwave reflection loss was studied. The composites were characterized using X-ray diffraction, a vibrating sample magnetometer, scanning electron microscopy, and a vector network analyzer. The XRD patterns of the sample without Nd3+ reveal the presence of BaFe12O19 (hexagonal) and BaFe2O4 (rhombohedral) phases. Furthermore, a new hexagonal crystal phase of Ba6Nd2Fe4O15 appeared after substituting Nd3+. The average size of the prepared barium-natural ferrite particles was estimated to be between 0.4 and 0.8 μm. Both saturation magnetization and microwave reflection losses of these barium-ferrites were significantly reduced by increasing the Nd3+ content.

  14. Diagnostic Accuracy of Multiparametric Magnetic Resonance Imaging and Fusion Guided Targeted Biopsy Evaluated by Transperineal Template Saturation Prostate Biopsy for the Detection and Characterization of Prostate Cancer.

    Science.gov (United States)

    Mortezavi, Ashkan; Märzendorfer, Olivia; Donati, Olivio F; Rizzi, Gianluca; Rupp, Niels J; Wettstein, Marian S; Gross, Oliver; Sulser, Tullio; Hermanns, Thomas; Eberli, Daniel

    2018-02-21

    We evaluated the diagnostic accuracy of multiparametric magnetic resonance imaging and multiparametric magnetic resonance imaging/transrectal ultrasound fusion guided targeted biopsy against that of transperineal template saturation prostate biopsy to detect prostate cancer. We retrospectively analyzed the records of 415 men who consecutively presented for prostate biopsy between November 2014 and September 2016 at our tertiary care center. Multiparametric magnetic resonance imaging was performed using a 3 Tesla device without an endorectal coil, followed by transperineal template saturation prostate biopsy with the BiopSee® fusion system. Additional fusion guided targeted biopsy was done in men with a suspicious lesion on multiparametric magnetic resonance imaging, defined as Likert score 3 to 5. Any Gleason pattern 4 was defined as clinically significant prostate cancer. The detection rates of multiparametric magnetic resonance imaging and fusion guided targeted biopsy were compared with the detection rate of transperineal template saturation prostate biopsy using the McNemar test. We obtained a median of 40 (range 30 to 55) and 3 (range 2 to 4) transperineal template saturation prostate biopsy and fusion guided targeted biopsy cores, respectively. Of the 124 patients (29.9%) without a suspicious lesion on multiparametric magnetic resonance imaging 32 (25.8%) were found to have clinically significant prostate cancer on transperineal template saturation prostate biopsy. Of the 291 patients (70.1%) with a Likert score of 3 to 5 clinically significant prostate cancer was detected in 129 (44.3%) by multiparametric magnetic resonance imaging fusion guided targeted biopsy, in 176 (60.5%) by transperineal template saturation prostate biopsy and in 187 (64.3%) by the combined approach. Overall 58 cases (19.9%) of clinically significant prostate cancer would have been missed if fusion guided targeted biopsy had been performed exclusively. The sensitivity of

  15. Natural convection in square cavity filled with ferrofluid saturated porous medium in the presence of uniform magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Javed, Tariq [Department of Mathematics and Statistics, FBAS, International Islamic University, Islamabad 44000 (Pakistan); Mehmood, Z., E-mail: rajaziafat@yahoo.com [Department of Mathematics and Statistics, FBAS, International Islamic University, Islamabad 44000 (Pakistan); Abbas, Z. [Department of Mathematics, The Islamia University, Bahawalpur (Pakistan)

    2017-02-01

    This article contains numerical results for free convection through square enclosure enclosing ferrofluid saturated porous medium when uniform magnetic field is applied upon the flow along x-axis. Heat is provided through bottom wall and a square blockage placed near left or right bottom corner of enclosure as a heat source. Left and right vertical boundaries of the cavity are considered insulated while upper wall is taken cold. The problem is modelled in terms of system of nonlinear partial differential equations. Finite element method has been adopted to compute numerical simulations of mathematical problem for wide range of pertinent flow parameters including Rayleigh number, Hartman number, Darcy number and Prandtl number. Analysis of results reveals that the strength of streamline circulation is an increasing function of Darcy and Prandtl number where convection heat transfer is dominant for large values of these parameters whereas increase in Hartman number has opposite effects on isotherms and streamline circulations. Thermal conductivity and hence local heat transfer rate of fluid gets increased when ferroparticles are introduced in the fluid. Average Nusselt number increases with increase in Darcy and Rayleigh numbers while it is decreases when Hartman number is increased.

  16. Natural convection in square cavity filled with ferrofluid saturated porous medium in the presence of uniform magnetic field

    International Nuclear Information System (INIS)

    Javed, Tariq; Mehmood, Z.; Abbas, Z.

    2017-01-01

    This article contains numerical results for free convection through square enclosure enclosing ferrofluid saturated porous medium when uniform magnetic field is applied upon the flow along x-axis. Heat is provided through bottom wall and a square blockage placed near left or right bottom corner of enclosure as a heat source. Left and right vertical boundaries of the cavity are considered insulated while upper wall is taken cold. The problem is modelled in terms of system of nonlinear partial differential equations. Finite element method has been adopted to compute numerical simulations of mathematical problem for wide range of pertinent flow parameters including Rayleigh number, Hartman number, Darcy number and Prandtl number. Analysis of results reveals that the strength of streamline circulation is an increasing function of Darcy and Prandtl number where convection heat transfer is dominant for large values of these parameters whereas increase in Hartman number has opposite effects on isotherms and streamline circulations. Thermal conductivity and hence local heat transfer rate of fluid gets increased when ferroparticles are introduced in the fluid. Average Nusselt number increases with increase in Darcy and Rayleigh numbers while it is decreases when Hartman number is increased.

  17. The off-resonant aspects of decoherence and a critique of the two-level approximation

    International Nuclear Information System (INIS)

    Savran, Kerim; Hakioglu, T; Mese, E; Sevincli, Haldun

    2006-01-01

    Conditions in favour of a realistic multilevelled description of a decohering quantum system are examined. In this regard the first crucial observation is that the thermal effects, contrary to the conventional belief, play a minor role at low temperatures in the decoherence properties. The system-environment coupling and the environmental energy spectrum dominantly affect the decoherence. In particular, zero temperature quantum fluctuations or non-equilibrium sources can be present and influential on the decoherence rates in a wide energy range allowed by the spectrum of the environment. A crucial observation against the validity of the two-level approximation is that the decoherence rates are found to be dominated not by the long time resonant but the short time off-resonant processes. This observation is demonstrated in two stages. Firstly, our zero temperature numerical results reveal that the calculated short time decoherence rates are Gaussian-like (the time dependence of the density matrix is led by the second time derivative at t = 0). Exact analytical results are also permitted in the short time limit, which, consistent with our numerical results, reveal that this specific Gaussian-like behaviour is a property of the non-Markovian correlations in the environment. These Gaussian-like rates have no dependence on any spectral parameter (position and the width of the spectrum) except, in totality, the spectral area itself. The dependence on the spectral area is a power law. Furthermore, the Gaussian-like character at short times is independent of the number of levels (N), but the numerical value of the decoherence rates is a monotonic function of N. In this context, we demonstrate that leakage, as a characteristic multilevel effect, is dominated by the non-resonant processes. The long time behaviour of decoherence is also examined. Since our spectral model allows Markovian environmental correlations at long times, the decoherence rates in this regime become

  18. Spin-locking of half-integer quadrupolar nuclei in NMR of solids: The far off-resonance case.

    Science.gov (United States)

    Odedra, Smita; Wimperis, Stephen

    Spin-locking of spin I=3/2 and I=5/2 nuclei in the presence of large resonance offsets has been studied using both approximate and exact theoretical approaches and, in the case of I=3/2, experimentally. We show the variety of coherences and population states produced in a far off-resonance spin-locking NMR experiment (one consisting solely of a spin-locking pulse) and how these vary with the radiofrequency field strength and offset frequency. Under magic angle spinning (MAS) conditions and in the "adiabatic limit", these spin-locked states acquire a time dependence. We discuss the rotor-driven interconversion of the spin-locked states, using an exact density matrix approach to confirm the results of the approximate model. Using conventional and multiple-quantum filtered spin-locking 23 Na (I=3/2) NMR experiments under both static and MAS conditions, we confirm the results of the theoretical calculations, demonstrating the applicability of the approximate theoretical model to the far off-resonance case. This simplified model includes only the effects of the initial rapid dephasing of coherences that occurs at the start of the spin-locking period and its success in reproducing both experimental and exact simulation data indicates that it is this dephasing that is the dominant phenomenon in NMR spin-locking of quadrupolar nuclei, as we have previously found for the on-resonance and near-resonance cases. Potentially, far off-resonance spin-locking of quadrupolar nuclei could be of interest in experiments such as cross polarisation as a consequence of the spin-locking pulse being applied to a better defined initial state (the thermal equilibrium bulk magnetisation aligned along the z-axis) than can be created in a powdered solid with a selective radiofrequency pulse, where the effect of the pulse depends on the orientation of the individual crystallites. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Enhanced saturation magnetization of Fe3Si nanodot-embedded Fe80Si17Nb3 flexible film for efficient wireless power transfer

    International Nuclear Information System (INIS)

    Pai, Yi-Hao; Yan, Zih-Yu; Fu, Ping-Hao

    2013-01-01

    An efficient magnetically coupled resonance response is performed using an iron silicide-based nanostructured magnetoelectric material with high saturation magnetization for the wireless charging of battery-powered consumer electronics. With 500 °C annealing, the self-assembled Fe 3 Si nanodots buried in the Fe 80 Si 17 Nb 3 host matrix with (220) lattice spacing of 1.99 Å corresponding to a volume density of 8.96 × 10 16 cm 3 , can be obtained and a maximum saturation magnetization of 244 emu g −1 achieved. The return loss of the antenna will be tuned to match the designed frequency with greater attenuated intensity (−0.39 dB) and a relatively narrow bandwidth (6 kHz) when the Fe 3 Si nanodot-embedded Fe 80 Si 17 Nb 3 sample is placed in a WiTricity system. An efficient wireless power transfer can be created and improved from 47.5% to 97.3%. The associated coil and loop antenna resonators are significantly readjusted to match the power transfer by putting this nanostructured magnetoelectric material in a WiTricity system. - Highlights: • The saturation magnetization is effective enhancement in the presence of Fe 3 Si nanodot buried in the Fe 80 Si 17 Nb 3 . • A saturation magnetization of 244 emu g −1 is proposed for high-efficiency wireless power transfer. • The return loss of the antenna will be tuned to match the designed frequency. • Such a wireless power transfer can be enhanced efficiency up to 97.3%

  20. Simultaneous multislice triple-echo steady-state (SMS-TESS) T1 , T2 , PD, and off-resonance mapping in the human brain.

    Science.gov (United States)

    Heule, Rahel; Celicanin, Zarko; Kozerke, Sebastian; Bieri, Oliver

    2018-02-21

    To investigate the ability of simultaneous multislice triple-echo steady-state (SMS-TESS) imaging to provide quantitative maps of multiple tissue parameters, i.e., longitudinal and transverse relaxation times (T 1 and T 2 ), proton density (PD), and off-resonance (ΔB 0 ), in the human brain at 3T from a single scan. TESS acquisitions were performed in 2D mode to reduce motion sensitivity and accelerated by an SMS excitation scheme (CAIPIRINHA) with SENSE reconstruction. SMS-acceleration factors (R) of 2 and 4 were evaluated. The in vitro and in vivo validation process included standard reference scans to analyze the accuracy of T 1 , T 2 , and ΔB 0 estimates, as well as single-slice TESS measurements. For R = 2, the quantification of T 1 , T 2 , PD, and ΔB 0 was overall reliable with marginal noise enhancement. T 1 and T 2 values were in good agreement with the reference measurements and single-slice TESS. For R = 4, the agreement of ΔB 0 with the standard reference was excellent and the determination of T 1 , T 2 , and PD was reproducible; however, increased variations in T 1 and T 2 values with respect to single-slice TESS were observed. SMS-TESS has shown potential to offer rapid simultaneous T 1 , T 2 , PD, and ΔB 0 mapping of human brain tissues. © 2018 International Society for Magnetic Resonance in Medicine.

  1. Anomalous solute transport in saturated porous media: Relating transport model parameters to electrical and nuclear magnetic resonance properties

    Science.gov (United States)

    Swanson, Ryan D; Binley, Andrew; Keating, Kristina; France, Samantha; Osterman, Gordon; Day-Lewis, Frederick D.; Singha, Kamini

    2015-01-01

    The advection-dispersion equation (ADE) fails to describe commonly observed non-Fickian solute transport in saturated porous media, necessitating the use of other models such as the dual-domain mass-transfer (DDMT) model. DDMT model parameters are commonly calibrated via curve fitting, providing little insight into the relation between effective parameters and physical properties of the medium. There is a clear need for material characterization techniques that can provide insight into the geometry and connectedness of pore spaces related to transport model parameters. Here, we consider proton nuclear magnetic resonance (NMR), direct-current (DC) resistivity, and complex conductivity (CC) measurements for this purpose, and assess these methods using glass beads as a control and two different samples of the zeolite clinoptilolite, a material that demonstrates non-Fickian transport due to intragranular porosity. We estimate DDMT parameters via calibration of a transport model to column-scale solute tracer tests, and compare NMR, DC resistivity, CC results, which reveal that grain size alone does not control transport properties and measured geophysical parameters; rather, volume and arrangement of the pore space play important roles. NMR cannot provide estimates of more-mobile and less-mobile pore volumes in the absence of tracer tests because these estimates depend critically on the selection of a material-dependent and flow-dependent cutoff time. Increased electrical connectedness from DC resistivity measurements are associated with greater mobile pore space determined from transport model calibration. CC was hypothesized to be related to length scales of mass transfer, but the CC response is unrelated to DDMT.

  2. Biochemical imaging of cervical intervertebral discs with glycosaminoglycan chemical exchange saturation transfer magnetic resonance imaging: feasibility and initial results

    International Nuclear Information System (INIS)

    Schleich, Christoph; Mueller-Lutz, Anja; Zimmermann, Lisa; Boos, Johannes; Wittsack, Hans-Joerg; Antoch, Gerald; Miese, Falk; Schmitt, Benjamin

    2016-01-01

    To evaluate glycosaminoglycan chemical exchange saturation transfer (gagCEST) imaging at 3T in the assessment of the GAG content of cervical IVDs in healthy volunteers. Forty-two cervical intervertebral discs of seven healthy volunteers (four females, three males; mean age: 21.4 ± 1.4 years; range: 19-24 years) were examined at a 3T MRI scanner in this prospective study. The MRI protocol comprised standard morphological, sagittal T2 weighted (T2w) images to assess the magnetic resonance imaging (MRI) based grading system for cervical intervertebral disc degeneration (IVD) and biochemical imaging with gagCEST to calculate a region-of-interest analysis of nucleus pulposus (NP) and annulus fibrosus (AF). GagCEST of cervical IVDs was technically successful at 3T with significant higher gagCEST values in NP compared to AF (1.17 % ± 1.03 % vs. 0.79 % ± 1.75 %; p = 0.005). We found topological differences of gagCEST values of the cervical spine with significant higher gagCEST effects in lower IVDs (r = 1; p = 0). We could demonstrate a significant, negative correlation between gagCEST values and cervical disc degeneration of NP (r = -0.360; p = 0.019). Non-degenerated IVDs had significantly higher gagCEST effects compared to degenerated IVDs in NP (1.76 % ± 0.92 % vs. 0.52 % ± 1.17 %; p < 0.001). Biochemical imaging of cervical IVDs is feasible at 3T. GagCEST analysis demonstrated a topological GAG distribution of the cervical spine. The depletion of GAG in the NP with increasing level of morphological degeneration can be assessed using gagCEST imaging. (orig.)

  3. Comparison of axial T1 spin-echo and T1 fat-saturation magnetic resonance imaging techniques in the diagnosis of chondromalacia patellae.

    Science.gov (United States)

    Vanarthos, W J; Pope, T L; Monu, J U

    1994-12-01

    To test the diagnostic value of T1 spin-echo and T1 fat-saturated magnetic resonance images (MRIs), we reviewed axial T1-weighted images with and without fat saturation in 20 patients with clinically suspected chondromalacia of the patella. All scans were obtained on 1.5-MR units. The scans were randomly ordered and reviewed independently at different times by two radiologists without knowledge of the arthroscopy results. The sensitivity of the individual techniques for detecting grade 3 or 4 chondromalacia patellae was 92% for fat-saturated axial T1-weighted images alone, and 67% for axial T1-weighted images without fat saturation. The sensitivity of the combined techniques was 100% for grades 3 and 4 and 90% for all grades (0 to 4). Chondromalacia patellae is diagnosed more accurately by using T1 fat saturation than by using T1 spin-echo images. With a combination of the two techniques, accuracy is 90% to 100%.

  4. Value of Perineural Edema/Inflammation Detected by Fat Saturation Sequences in Lumbar Magnetic Resonance Imaging of Patients with Unilateral Sciatica

    Energy Technology Data Exchange (ETDEWEB)

    Sirvanci, M.; Duran, C. (Dept. of Radiology, Faculty of Medicine, Istanbul Bilim Univ., Istanbul (Turkey)); Kara, B.; Onat, L.; Ulusoy, O.L.; Mutlu, A. (Dept. of Radiology of Florence Nightingale Hospital, Istanbul (Turkey)); Ozturk, E. (Dept. of Radiology, GATA Haydarpasa Teaching Hospital, Istanbul (Turkey)); Karatoprak, O. (Dept. of Orthopeadic Surgery, Kadikoy Florence Nightingale Hospital, Istanbul (Turkey))

    2009-02-15

    Background: Routine lumbar spine magnetic resonance imaging (MRI) may not show any evidence of the cause of sciatica in some cases. The relationship between nerve root compression detected on lumbar MRI and sciatica is also sometimes uncertain. Purpose: To ascertain whether axial (and, when necessary, sagittal and coronal) short-tau inversion recovery or fat-saturated T2-weighted MRI findings can be used to study the level of sciatica in patients with a non-yielding routine MRI examination. Material and Methods: A total of 215 patients with unilateral sciatica underwent MRI. All patients were asked to complete pain drawing forms describing their pain dermatomal distributions. Perineural edema/inflammation corresponding to the pain location indicated by the pain drawings was sought on short-tau inversion recovery or fat-saturated T2-weighted images. Results: Routine MRI findings revealed that 110 of the 215 patients had nerve root compromise related to the patients' symptoms. Routine MRI could not ascertain the cause of these symptoms in the remaining 105 patients. In 31 (29.5%) of these 105 patients, short-tau inversion recovery or fat-saturated T2-weighted magnetic resonance images revealed perineural edema/inflammation surrounding the nerve roots related to the pain locations indicated in the pain drawings. Conclusion: Axial (and, when required, sagittal and coronal) short-tau inversion recovery or fat-saturated T2-weighted magnetic resonance images may be helpful for revealing additional findings in cases of unexplained sciatica in standard magnetic resonance imaging. However, the value of this imaging may be not great enough to justify routine use of these additional sequences to study the level of sciatica

  5. Value of Perineural Edema/Inflammation Detected by Fat Saturation Sequences in Lumbar Magnetic Resonance Imaging of Patients with Unilateral Sciatica

    International Nuclear Information System (INIS)

    Sirvanci, M.; Duran, C.; Kara, B.; Onat, L.; Ulusoy, O.L.; Mutlu, A.; Ozturk, E.; Karatoprak, O.

    2009-01-01

    Background: Routine lumbar spine magnetic resonance imaging (MRI) may not show any evidence of the cause of sciatica in some cases. The relationship between nerve root compression detected on lumbar MRI and sciatica is also sometimes uncertain. Purpose: To ascertain whether axial (and, when necessary, sagittal and coronal) short-tau inversion recovery or fat-saturated T2-weighted MRI findings can be used to study the level of sciatica in patients with a non-yielding routine MRI examination. Material and Methods: A total of 215 patients with unilateral sciatica underwent MRI. All patients were asked to complete pain drawing forms describing their pain dermatomal distributions. Perineural edema/inflammation corresponding to the pain location indicated by the pain drawings was sought on short-tau inversion recovery or fat-saturated T2-weighted images. Results: Routine MRI findings revealed that 110 of the 215 patients had nerve root compromise related to the patients' symptoms. Routine MRI could not ascertain the cause of these symptoms in the remaining 105 patients. In 31 (29.5%) of these 105 patients, short-tau inversion recovery or fat-saturated T2-weighted magnetic resonance images revealed perineural edema/inflammation surrounding the nerve roots related to the pain locations indicated in the pain drawings. Conclusion: Axial (and, when required, sagittal and coronal) short-tau inversion recovery or fat-saturated T2-weighted magnetic resonance images may be helpful for revealing additional findings in cases of unexplained sciatica in standard magnetic resonance imaging. However, the value of this imaging may be not great enough to justify routine use of these additional sequences to study the level of sciatica

  6. Computational study of plasma-assisted photoacoustic response from gold nanoparticles irradiated by off-resonance ultrafast laser

    International Nuclear Information System (INIS)

    Hatef, Ali; Darvish, Behafarid; Sajjadi, Amir Yousef

    2017-01-01

    The gold nanoparticles (AuNPs) are capable of enhancing the incident laser field in the form of scattered near field for even an off-resonance irradiation where the incident laser wavelength is far away from the localized surface plasmon resonance (LSPR). If the intensity of the pulse laser is large enough, this capability can be employed to generate a highly localized free electron (plasma) in the vicinity of the particles. The generated plasma can absorb more energy during the pulse, and this energy deposition can be considered as an energy source for structural mechanics calculations in the surrounding media to generate a photoacoustic (PA) signal. To show this, in this paper, we model plasma-mediated PA pressure wave propagation from a 100-nm AuNPs and the surrounding media irradiated by an ultrashort pulse laser. In this model, the AuNP is immersed in water and the laser pulse width is ranging from 70 fs to 2 ps at the wavelength of 800 nm (off-resonance). Our results qualitatively show the substantial impact of the energy deposition in plasma on the PA signal through boosting the pressure amplitudes up to ∼1000 times compared to the conventional approach.

  7. Computational study of plasma-assisted photoacoustic response from gold nanoparticles irradiated by off-resonance ultrafast laser

    Energy Technology Data Exchange (ETDEWEB)

    Hatef, Ali, E-mail: alih@nipissingu.ca; Darvish, Behafarid [Nipissing University, Nipissing Computational Physics Laboratory (NCPL), Department of Computer Science and Mathematics (Canada); Sajjadi, Amir Yousef [Massachusetts General Hospital, Cutaneous Biology Research Center (United States)

    2017-02-15

    The gold nanoparticles (AuNPs) are capable of enhancing the incident laser field in the form of scattered near field for even an off-resonance irradiation where the incident laser wavelength is far away from the localized surface plasmon resonance (LSPR). If the intensity of the pulse laser is large enough, this capability can be employed to generate a highly localized free electron (plasma) in the vicinity of the particles. The generated plasma can absorb more energy during the pulse, and this energy deposition can be considered as an energy source for structural mechanics calculations in the surrounding media to generate a photoacoustic (PA) signal. To show this, in this paper, we model plasma-mediated PA pressure wave propagation from a 100-nm AuNPs and the surrounding media irradiated by an ultrashort pulse laser. In this model, the AuNP is immersed in water and the laser pulse width is ranging from 70 fs to 2 ps at the wavelength of 800 nm (off-resonance). Our results qualitatively show the substantial impact of the energy deposition in plasma on the PA signal through boosting the pressure amplitudes up to ∼1000 times compared to the conventional approach.

  8. In vivo 31P nuclear magnetic resonance saturation transfer measurements of phosphate exchange reactions in the yeast Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Campbell, S.L.; Jones, K.A.; Schulman, R.G.

    1985-01-01

    31 P saturation transfer techniques have been used to measure phosphate kinetics in the yeast Saccharomyces cerevisiae. The phosphate comsumption rate observed in acetate grown mid-log cells was combined with measurements of O 2 consumption to yield P/O ratios of 2.2 and 2.9, for cells respiring on glucose and ethanol, respectively. However, no phosphate consumption activity was observed in saturation transfer experiments on anaerobic glucose fed cells. The phosphate consumption rates measured by saturation transfer in cells respiring on glucose and ethanol was attributed to the unidirectional rates of mitochondrial ATP synthesis. (Auth.)

  9. Spin-locking vs. chemical exchange saturation transfer MRI for investigating chemical exchange process between water and labile metabolite protons

    Science.gov (United States)

    Jin, Tao; Autio, Joonas; Obata, Takayuki; Kim, Seong-Gi

    2010-01-01

    Chemical exchange saturation transfer (CEST) and spin-locking (SL) experiments were both able to probe the exchange process between protons of non-equivalent chemical environments. To compare the characteristics of the CEST and SL approaches in the study of chemical exchange effects, we performed CEST and SL experiments at varied pH and concentrated metabolites with exchangeable amide, amine, and hydroxyl protons at 9.4 T. Our results show that: i) On-resonance SL is most sensitive to chemical exchanges in the intermediate exchange regime and is able to detect hydroxyl and amine protons on a millimolar concentration scale. Off-resonance SL and CEST approaches are sensitive to slow-exchanging protons when an optimal SL or saturation pulse power matches the exchanging rate, respectively. ii) Offset frequency-dependent SL and CEST spectra are very similar, and can be explained well with an SL model recently developed by Trott and Palmer. iii) The exchange rate and population of metabolite protons can be determined from offset-dependent SL or CEST spectra or from on-resonance SL relaxation dispersion measurements. iv) The asymmetry of the magnetization transfer ratio (MTRasym) is highly dependent on the choice of saturation pulse power. In the intermediate exchange regime, MTRasym becomes complicated and should be interpreted with care. PMID:21500270

  10. Spin-locking versus chemical exchange saturation transfer MRI for investigating chemical exchange process between water and labile metabolite protons.

    Science.gov (United States)

    Jin, Tao; Autio, Joonas; Obata, Takayuki; Kim, Seong-Gi

    2011-05-01

    Chemical exchange saturation transfer (CEST) and spin-locking (SL) experiments were both able to probe the exchange process between protons of nonequivalent chemical environments. To compare the characteristics of the CEST and SL approaches in the study of chemical exchange effects, we performed CEST and SL experiments at varied pH and concentrated metabolite phantoms with exchangeable amide, amine, and hydroxyl protons at 9.4 T. Our results show that: (i) on-resonance SL is most sensitive to chemical exchanges in the intermediate-exchange regime and is able to detect hydroxyl and amine protons on a millimolar concentration scale. Off-resonance SL and CEST approaches are sensitive to slow-exchanging protons when an optimal SL or saturation pulse power matches the exchanging rate, respectively. (ii) Offset frequency-dependent SL and CEST spectra are very similar and can be explained well with an SL model recently developed by Trott and Palmer (J Magn Reson 2002;154:157-160). (iii) The exchange rate and population of metabolite protons can be determined from offset-dependent SL or CEST spectra or from on-resonance SL relaxation dispersion measurements. (iv) The asymmetry of the magnetization transfer ratio (MTR(asym)) is highly dependent on the choice of saturation pulse power. In the intermediate-exchange regime, MTR(asym) becomes complicated and should be interpreted with care. Copyright © 2010 Wiley-Liss, Inc.

  11. Assessment of the patellofemoral cartilage: Correlation of knee pain score with magnetic resonance cartilage grading and magnetization transfer ratio asymmetry of glycosaminoglycan chemical exchange saturation transfer.

    Science.gov (United States)

    Lee, Young Han; Yang, Jaemoon; Jeong, Ha-Kyu; Suh, Jin-Suck

    2017-01-01

    Biochemical imaging of glycosaminoglycan chemical exchange saturation transfer (gagCEST) could predict the depletion of glycosaminoglycans (GAG) in early osteoarthritis. The purpose of this study was to evaluate the relationship between the magnetization transfer ratio asymmetry (MTR asym ) of gagCEST images and visual analog scale (VAS) pain scores in the knee joint. This retrospective study was approved by the institutional review board. A phantom study was performed using hyaluronic acid to validate the MTR asym values of gagCEST images. Knee magnetic resonance (MR) images of 22 patients (male, 9; female, 13; mean age, 50.3years; age range; 25-79years) with knee pain were included in this study. The MR imaging (MRI) protocol involved standard knee MRI as well as gagCEST imaging, which allowed region-of-interest analyses of the patellar facet and femoral trochlea. The MTR asym at 1.0ppm was calculated at each region. The cartilages of the patellar facets and femoral trochlea were graded according to the Outerbridge classification system. Data regarding the VAS scores of knee pain were collected from the electronic medical records of the patients. Statistical analysis was performed using Spearman's correlation. The results of the phantom study revealed excellent correlation between the MTR asym values and the concentration of GAGs (r=0.961; p=0.003). The cartilage grades on the MR images showed significant negative correlation with the MTR asym values in the patellar facet and femoral trochlea (r=-0.460; p=0.031 and r=-0.543; p=0.009, respectively). The VAS pain scores showed significant negative correlation with the MTR asym values in the patellar facet and femoral trochlea (r=-0.435; p=0.043 and r=-0.671; p=0.001, respectively). The pain scores were associated with the morphological and biochemical changes in articular cartilages visualized on knee MR images. The biochemical changes, visualized in terms of the MTR asym values of the gagCEST images, exhibited

  12. Ion cyclotron instability saturation and turbulent plasma heating in the presence of ions moving across the magnetic field

    International Nuclear Information System (INIS)

    Mikhajlenko, V.S.; Stepanov, K.N.

    1981-01-01

    Ion cyclotron instability saturation is considered in terms of the turbulence theory when there is a beam of heavy ions with large thermal longitudinal velocity spread. The instability excitation is due to a cyclotron interaction with ions of the beam under the anomalous Doppler effect. The instability is shown to be saturated due to an induced plasma ion scattering of ion cyclotron waves when the beam ion charge number Zsub(b) is approximately 1. Decay processes, wave scattering by virtual wave polarization clouds and resonance broadening due to random walk of plasma ions in turbulent instability fields appear to be unimportant. For Zsub(b)>>1 the induced wave scattering by the beam ions is the main process determining the nonlinear stage of the instability. Estimates are given for the oscillation energy density in the instability saturation state and for the turbulent heating rate of plasma and beam ions [ru

  13. Improved cerebral time-of-flight magnetic resonance angiography at 7 Tesla--feasibility study and preliminary results using optimized venous saturation pulses.

    Directory of Open Access Journals (Sweden)

    Karsten H Wrede

    Full Text Available PURPOSE: Conventional saturation pulses cannot be used for 7 Tesla ultra-high-resolution time-of-flight magnetic resonance angiography (TOF MRA due to specific absorption rate (SAR limitations. We overcome these limitations by utilizing low flip angle, variable rate selective excitation (VERSE algorithm saturation pulses. MATERIAL AND METHODS: Twenty-five neurosurgical patients (male n = 8, female n = 17; average age 49.64 years; range 26-70 years with different intracranial vascular pathologies were enrolled in this trial. All patients were examined with a 7 Tesla (Magnetom 7 T, Siemens whole body scanner system utilizing a dedicated 32-channel head coil. For venous saturation pulses a 35° flip angle was applied. Two neuroradiologists evaluated the delineation of arterial vessels in the Circle of Willis, delineation of vascular pathologies, presence of artifacts, vessel-tissue contrast and overall image quality of TOF MRA scans in consensus on a five-point scale. Normalized signal intensities in the confluence of venous sinuses, M1 segment of left middle cerebral artery and adjacent gray matter were measured and vessel-tissue contrasts were calculated. RESULTS: Ratings for the majority of patients ranged between good and excellent for most of the evaluated features. Venous saturation was sufficient for all cases with minor artifacts in arteriovenous malformations and arteriovenous fistulas. Quantitative signal intensity measurements showed high vessel-tissue contrast for confluence of venous sinuses, M1 segment of left middle cerebral artery and adjacent gray matter. CONCLUSION: The use of novel low flip angle VERSE algorithm pulses for saturation of venous vessels can overcome SAR limitations in 7 Tesla ultra-high-resolution TOF MRA. Our protocol is suitable for clinical application with excellent image quality for delineation of various intracranial vascular pathologies.

  14. Improved Cerebral Time-of-Flight Magnetic Resonance Angiography at 7 Tesla – Feasibility Study and Preliminary Results Using Optimized Venous Saturation Pulses

    Science.gov (United States)

    Wrede, Karsten H.; Johst, Sören; Dammann, Philipp; Özkan, Neriman; Mönninghoff, Christoph; Kraemer, Markus; Maderwald, Stefan; Ladd, Mark E.; Sure, Ulrich; Umutlu, Lale; Schlamann, Marc

    2014-01-01

    Purpose Conventional saturation pulses cannot be used for 7 Tesla ultra-high-resolution time-of-flight magnetic resonance angiography (TOF MRA) due to specific absorption rate (SAR) limitations. We overcome these limitations by utilizing low flip angle, variable rate selective excitation (VERSE) algorithm saturation pulses. Material and Methods Twenty-five neurosurgical patients (male n = 8, female n = 17; average age 49.64 years; range 26–70 years) with different intracranial vascular pathologies were enrolled in this trial. All patients were examined with a 7 Tesla (Magnetom 7 T, Siemens) whole body scanner system utilizing a dedicated 32-channel head coil. For venous saturation pulses a 35° flip angle was applied. Two neuroradiologists evaluated the delineation of arterial vessels in the Circle of Willis, delineation of vascular pathologies, presence of artifacts, vessel-tissue contrast and overall image quality of TOF MRA scans in consensus on a five-point scale. Normalized signal intensities in the confluence of venous sinuses, M1 segment of left middle cerebral artery and adjacent gray matter were measured and vessel-tissue contrasts were calculated. Results Ratings for the majority of patients ranged between good and excellent for most of the evaluated features. Venous saturation was sufficient for all cases with minor artifacts in arteriovenous malformations and arteriovenous fistulas. Quantitative signal intensity measurements showed high vessel-tissue contrast for confluence of venous sinuses, M1 segment of left middle cerebral artery and adjacent gray matter. Conclusion The use of novel low flip angle VERSE algorithm pulses for saturation of venous vessels can overcome SAR limitations in 7 Tesla ultra-high-resolution TOF MRA. Our protocol is suitable for clinical application with excellent image quality for delineation of various intracranial vascular pathologies. PMID:25232868

  15. Fat-saturated, contrast-enhanced spin echo sequences in magnetic resonance tomographic diagnosis of peritoneal carcinosis

    International Nuclear Information System (INIS)

    Ricke, J.; Hosten, N.; Stroszczynski, C.; Amthauer, H.; Felix, R.; Sehouli, J.; Buchmann, E.; Rieger, J.

    1999-01-01

    Purpose: To evaluate contrast-enhanced, fat-saturated spin echo sequences for the detection of peritoneal carcinosis with MRI. Material and Methods: 61 patients, 35 with and 26 without peritoneal carcinosis, were examined with abdominal MRI. Fat-saturated, T 1 -weighted spin echo sequences were performed before and after administration of Gd-DTPA. In addition, 22 patients with peritoneal carcinosis were examined with contrast-enhanced abdominal CT. Results: 32 of 35 patients with peritoneal carcinosis demonstrated contrast enhancement of the visceral and 30 to 35 enhancement of the parietal peritoneum (91 and 86%, respectively). Wall thickening of the intestine or parietal peritoneum were noted in 21 and 20 of 35 patients (60 and 57%, respectively), ascites in 18 of 35 patients (51%). False positive contrast enhancement of the peritoneum was noted in 4 of 26 patients (15%). In the direct comparison of MRI and CT, 22 of 22 patients versus 7 of 22 patients showed contrast enhancement of the visceral peritoneum (100 and 32%, respectively). For other signs of peritoneal carcinosis (e.g., ascites, peritoneal seedings), no differences in diagnostic reliability were demonstrated. Conclusions: The use of fat-saturated, spin echo sequences facilitates the diagnosis of peritoneal carcinosis by artifact reduction and improved detection of peritoneal contrast enhancement. MRI with fat-saturated sequences was superior to CT. (orig.) [de

  16. Preparation of metastable CoFeNi alloys with ultra-high magnetic saturation (Bs = 2.4-2.59 T) by reverse pulse electrodeposition

    Science.gov (United States)

    Tabakovic, Ibro; Venkatasamy, Venkatram

    2018-04-01

    The results of reverse pulse electrodeposition of CoFeNi films with ultra-high magnetic saturation, i.e. Bs values between 2.4 and 2.59 T, are presented in this work. Based on valence-bond theory (Hund's rule) it was assumed that the electronic configuration of MOH obtained by one electron reduction of electroactive intermediate (MOH+ads + e → MOHads) or oxidation of metal (M - e + HOH → MOH + H+) would result with larger number of spins per atom for each of transition metals in MOH-precipitated in CoFeNi deposit- with one more spin than their respective neutral metal in the order: Fe > Co > Ni. The experimental results showed that the increase of Bs value above Slater-Pauling curve was not observed for CoFe alloys, thus FeOH and CoOH compounds were not present in deposit. However, the increase of the Bs values above the Slater-Pauling curve (Bs = 2.4-2.59 T) was observed, for CoFeNi films obtained by reverse pulse electrodeposition. Therefore, NiOH as a stable compound is probably formed in a one-electron oxidation step during anodic pulse oxidation reaction precipitated presumably at the grain boundaries, giving rise to the ultra-high magnetic saturation of CoFeNi films. The effects of experimental conditions on elemental composition, magnetic properties, crystal structure, and thermal stability of CoFeNi films were studied.

  17. Synthesis of iron oxides nanoparticles with very high saturation magnetization form TEA-Fe(III) complex via electrochemical deposition for supercapacitor applications

    Science.gov (United States)

    Elrouby, Mahmoud; Abdel-Mawgoud, A. M.; El-Rahman, Rehab Abd

    2017-11-01

    This work is devoted to the synthesis of magnetic iron oxides nanoparticles with very high saturation magnetization to be qualified for supercapacitor applications using, a simple electrodeposition technique. It is found that the electrochemical reduction process depends on concentration, temperature, deposition potential and the scan rate of potential. The nature of electrodeposition process has been characterized via voltammetric and chronoamperometric techniques. The morphology of the electrodeposits has been investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The structure and phase content of these investigated electrodeposits have been examined and calculated. The obtained iron oxides show a high saturation magnetization (Ms) of about 229 emu g-1. The data exhibited a relation between Ms of electrodeposited iron oxide and specific capacitance. This relation exhibits that the highest Ms value of electrodeposited iron oxides gives also highest specific capacitance of about 725 Fg-1. Moreover, the electrodeposited iron oxides exhibit a very good stability. The new characteristics of the electro synthesized iron oxides at our optimized conditions, strongly qualify them as a valuable material for high-performance supercapacitor applications.

  18. Multi-frequency modes in superconducting resonators: Bridging frequency gaps in off-resonant couplings

    Science.gov (United States)

    Andersen, Christian Kraglund; Mølmer, Klaus

    2015-03-01

    A SQUID inserted in a superconducting waveguide resonator imposes current and voltage boundary conditions that makes it suitable as a tuning element for the resonator modes. If such a SQUID element is subject to a periodically varying magnetic flux, the resonator modes acquire frequency side bands. We calculate the multi-frequency eigenmodes and these can couple resonantly to physical systems with different transition frequencies and this makes the resonator an efficient quantum bus for state transfer and coherent quantum operations in hybrid quantum systems. As an example of the application, we determine their coupling to transmon qubits with different frequencies and we present a bi-chromatic scheme for entanglement and gate operations. In this calculation, we obtain a maximally entangled state with a fidelity F = 95 % . Our proposal is competitive with the achievements of other entanglement-gates with superconducting devices and it may offer some advantages: (i) There is no need for additional control lines and dephasing associated with the conventional frequency tuning of qubits. (ii) When our qubits are idle, they are far detuned with respect to each other and to the resonator, and hence they are immune to cross talk and Purcell-enhanced decay.

  19. Double agents and secret agents: the emerging fields of exogenous chemical exchange saturation transfer and T2-exchange magnetic resonance imaging contrast agents for molecular imaging.

    Science.gov (United States)

    Daryaei, Iman; Pagel, Mark D

    2015-01-01

    Two relatively new types of exogenous magnetic resonance imaging contrast agents may provide greater impact for molecular imaging by providing greater specificity for detecting molecular imaging biomarkers. Exogenous chemical exchange saturation transfer (CEST) agents rely on the selective saturation of the magnetization of a proton on an agent, followed by chemical exchange of a proton from the agent to water. The selective detection of a biomarker-responsive CEST signal and an unresponsive CEST signal, followed by the ratiometric comparison of these signals, can improve biomarker specificity. We refer to this improvement as a "double-agent" approach to molecular imaging. Exogenous T 2 -exchange agents also rely on chemical exchange of protons between the agent and water, especially with an intermediate rate that lies between the slow exchange rates of CEST agents and the fast exchange rates of traditional T 1 and T 2 agents. Because of this intermediate exchange rate, these agents have been relatively unknown and have acted as "secret agents" in the contrast agent research field. This review exposes these secret agents and describes the merits of double agents through examples of exogenous agents that detect enzyme activity, nucleic acids and gene expression, metabolites, ions, redox state, temperature, and pH. Future directions are also provided for improving both types of contrast agents for improved molecular imaging and clinical translation. Therefore, this review provides an overview of two new types of exogenous contrast agents that are becoming useful tools within the armamentarium of molecular imaging.

  20. Breaking the Carnot limit without violating the second law: A thermodynamic analysis of off-resonant quantum light generation

    Science.gov (United States)

    Boukobza, E.; Ritsch, H.

    2013-06-01

    The Carnot limit, formulated in 1824, represents the maximal efficiency of a classical heat engine. In this work we present a thermodynamical analysis of a light amplifier based on a three-level atom coupled off-resonantly to a single quantized cavity mode and to two heat reservoirs with positive temperatures. Based on standard work and heat flow equilibrium, we show that for a cavity blue-detuned with respect to the atomic resonance, the system can surpass the Carnot limit. Nevertheless, the second law of thermodynamics is still obeyed, as the total entropy always increases. By analyzing a semiclassical version of the model, we derive a formula for the critical frequency for which the Carnot limit is broken and a formula for the amplifier efficiency which agrees with its quantum counterpart. In the semiclassical regime, however, the second law is not satisfied and hence it does not offer a physically acceptable description of the system. Finally, we show that breaking the Carnot limit occurs also in a blue-detuned quantum amplifier with output coupling, which represents a realistic model of a laser or maser.

  1. In situ detection of atomic and molecular iodine using Resonance and Off-Resonance Fluorescence by Lamp Excitation: ROFLEX

    Directory of Open Access Journals (Sweden)

    J. C. Gómez Martín

    2011-01-01

    Full Text Available We demonstrate a new instrument for in situ detection of atmospheric iodine atoms and molecules based on atomic and molecular resonance and off-resonance ultraviolet fluorescence excited by lamp emission. The instrument combines the robustness, light weight, low power consumption and efficient excitation of radio-frequency discharge light sources with the high sensitivity of the photon counting technique. Calibration of I2 fluorescence is achieved via quantitative detection of the molecule by Incoherent Broad Band Cavity-enhanced Absorption Spectroscopy. Atomic iodine fluorescence signal is calibrated by controlled broad band photolysis of known I2 concentrations in the visible spectral range at atmospheric pressure. The instrument has been optimised in laboratory experiments to reach detection limits of 1.2 pptv for I atoms and 13 pptv for I2, for S/N = 1 and 10 min of integration time. The ROFLEX system has been deployed in a field campaign in northern Spain, representing the first concurrent observation of ambient mixing ratios of iodine atoms and molecules in the 1–350 pptv range.

  2. Photoinduced intermolecular electron transfer and off-resonance Raman characteristics of Rhodamine 101/N,N-diethylaniline

    International Nuclear Information System (INIS)

    Jiang, Li-lin; Liu, Wei-long; Song, Yun-fei; He, Xing; Wang, Yang; Wang, Chang; Wu, Hong-lin; Yang, Fang; Yang, Yan-qiang

    2014-01-01

    Highlights: • Mechanism of PIET reaction process for the Rh101 + /DEA system is investigated. • The significant geometrical changes of the charge–transfer complex are explained. • Forward Electron transfer from DEA to Rh101 +∗ occurs with lifetime of 425–560 fs. • Backward electron transfer occurs with a time constant of 46.16–51.40 ps. • Intramolecular vibrational relaxation occurs with lifetime of 2.77–5.39 ps. - Abstract: The ultrafast photoinduced intermolecular electron transfer (PIET) reaction of Rhodamine 101 (Rh101 + ) in N,N-diethylaniline (DEA) was investigated using off-resonance Raman, femtosecond time-resolved multiplex transient grating (TG) and transient absorption (TA) spectroscopies. The Raman spectra indicate that the C=C stretching vibration of the chromophore aromatic ring is more sensitive to ET compared with the C-C stretching mode. The ultrafast photoinduced intermolecular forward ET (FET) from DEA to Rh101 +∗ occurs on a time scale of τ FET = 425–560 fs. The backward ET (BET) occurs in the inverted region with a time constant of τ BET = 46.16–51.40 ps. The intramolecular vibrational relaxation (IVR) process occurs on the excited state potential energy surface with the time constant of τ IVR = 2.77–5.39 ps

  3. Quantum-coherence-assisted tunable on- and off-resonance tunneling through a quantum-dot-molecule dielectric film

    International Nuclear Information System (INIS)

    Shen Jianqi; Zeng Ruixi

    2017-01-01

    Quantum-dot-molecular phase coherence (and the relevant quantum-interference-switchable optical response) can be utilized to control electromagnetic wave propagation via a gate voltage, since quantum-dot molecules can exhibit an effect of quantum coherence (phase coherence) when quantum-dot-molecular discrete multilevel transitions are driven by an electromagnetic wave. Interdot tunneling of carriers (electrons and holes) controlled by the gate voltage can lead to destructive quantum interference in a quantum-dot molecule that is coupled to an incident electromagnetic wave, and gives rise to a quantum coherence effect (e.g., electromagnetically induced transparency, EIT) in a quantum-dot-molecule dielectric film. The tunable on- and off-resonance tunneling effect of an incident electromagnetic wave (probe field) through such a quantum-coherent quantum-dot-molecule dielectric film is investigated. It is found that a high gate voltage can lead to the EIT phenomenon of the quantum-dot-molecular systems. Under the condition of on-resonance light tunneling through the present quantum-dot-molecule dielectric film, the probe field should propagate without loss if the probe frequency detuning is zero. Such an effect caused by both EIT and resonant tunneling, which is sensitive to the gate voltage, can be utilized for designing devices such as photonic switching, transistors, and logic gates. (author)

  4. Photoinduced intermolecular electron transfer and off-resonance Raman characteristics of Rhodamine 101/N,N-diethylaniline

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Li-lin [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); School of Mechanical and Electronic Engineering, Hezhou University, Hezhou 542800 (China); Liu, Wei-long; Song, Yun-fei; He, Xing; Wang, Yang; Wang, Chang; Wu, Hong-lin [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Yang, Fang [National Key Laboratory of Science and Technology on Tunable Laser, Department of Optoelectronics Information Science Technology, Harbin Institute of Technology, Harbin 150001 (China); Yang, Yan-qiang, E-mail: yqyang@hit.edu.cn [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900, Sichuan (China)

    2014-01-31

    Highlights: • Mechanism of PIET reaction process for the Rh101{sup +}/DEA system is investigated. • The significant geometrical changes of the charge–transfer complex are explained. • Forward Electron transfer from DEA to Rh101{sup +∗} occurs with lifetime of 425–560 fs. • Backward electron transfer occurs with a time constant of 46.16–51.40 ps. • Intramolecular vibrational relaxation occurs with lifetime of 2.77–5.39 ps. - Abstract: The ultrafast photoinduced intermolecular electron transfer (PIET) reaction of Rhodamine 101 (Rh101{sup +}) in N,N-diethylaniline (DEA) was investigated using off-resonance Raman, femtosecond time-resolved multiplex transient grating (TG) and transient absorption (TA) spectroscopies. The Raman spectra indicate that the C=C stretching vibration of the chromophore aromatic ring is more sensitive to ET compared with the C-C stretching mode. The ultrafast photoinduced intermolecular forward ET (FET) from DEA to Rh101{sup +∗} occurs on a time scale of τ{sub FET} = 425–560 fs. The backward ET (BET) occurs in the inverted region with a time constant of τ{sub BET} = 46.16–51.40 ps. The intramolecular vibrational relaxation (IVR) process occurs on the excited state potential energy surface with the time constant of τ{sub IVR} = 2.77–5.39 ps.

  5. Enhanced off-resonance magnetoelectric response in laser annealed PZT thick film grown on magnetostrictive amorphous metal substrate

    Energy Technology Data Exchange (ETDEWEB)

    Palneedi, Haribabu [Materials Interface Laboratory, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea, Republic of); Functional Ceramics Group, Korea Institute of Materials Science (KIMS), Changwon 641-831 (Korea, Republic of); Maurya, Deepam; Priya, Shashank [Bio-inspired Materials and Devices Laboratory (BMDL), Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States); Kim, Gi-Yeop; Choi, Si-Young, E-mail: youngchoi@kims.re.kr [Materials Modeling and Characterization Department, Korea Institute of Materials Science (KIMS), Changwon 641-831 (Korea, Republic of); Kang, Suk-Joong L. [Materials Interface Laboratory, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701 (Korea, Republic of); Kim, Kwang-Ho [School of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Ryu, Jungho, E-mail: jhryu@kims.re.kr [Functional Ceramics Group, Korea Institute of Materials Science (KIMS), Changwon 641-831 (Korea, Republic of)

    2015-07-06

    A highly dense, 4 μm-thick Pb(Zr,Ti)O{sub 3} (PZT) film is deposited on amorphous magnetostrictive Metglas foil (FeBSi) by granule spray in vacuum process at room temperature, followed by its localized annealing with a continuous-wave 560 nm ytterbium fiber laser radiation. This longer-wavelength laser radiation is able to anneal the whole of thick PZT film layer without any deteriorative effects, such as chemical reaction and/or atomic diffusion, at the interface and crystallization of amorphous Metglas substrate. Greatly enhanced dielectric and ferroelectric properties of the annealed PZT are attributed to its better crystallinity and grain growth induced by laser irradiation. As a result, a colossal off-resonance magnetoelectric (ME) voltage coefficient that is two orders of magnitude larger than previously reported output from PZT/Metglas film-composites is achieved. The present work addresses the problems involved in the fabrication of PZT/Metglas film-composites and opens up emerging possibilities in employing piezoelectric materials with low thermal budget substrates (suitable for integrated electronics) and designing laminate composites for ME based devices.

  6. 31P nuclear magnetic resonance spectroscopy studies of tumor energy metabolism and its relationship to intracapillary oxyhemoglobin saturation status and tumor hypoxia.

    Science.gov (United States)

    Rofstad, E K; DeMuth, P; Fenton, B M; Sutherland, R M

    1988-10-01

    Relationships between tumor bioenergetic status on the one hand and intracapillary oxyhemoglobin (HbO2) saturation status and fraction of radiobiologically hypoxic cells on the other were studied using two murine sarcoma lines (KHT, RIF-1) and two human ovarian carcinoma xenograft lines (MLS, OWI). Tumor energy metabolism was studied in vivo by 31P nuclear magnetic resonance (NMR) spectroscopy and the resonance area ratio (PCr + NTP beta)/Pi was used as parameter for bioenergetic status. Intracapillary HbO2 saturation status reflects the oxygen supply conditions in tumors and was measured in vitro using a cryospectrophotometric method. The KHT, RIF-1, and MLS lines showed decreasing bioenergetic status, i.e., decreasing PCr and NTP beta resonances and an increasing Pi resonance, with increasing tumor volume, whereas the OWI line showed no changes in these resonances during tumor growth. The volume-dependence of the HbO2 saturation status differed similarly among the tumor lines; HbO2 saturation status decreased with increasing tumor volume for the KHT, RIF-1, and MLS lines and was independent of tumor volume for the OWI line. Moreover, linear correlations were found between bioenergetic status and HbO2 saturation status for individual tumors of the KHT, RIF-1, and MLS lines. These observations together indicated a direct relationship between 31P-NMR spectral parameters and tumor oxygen supply conditions. However, this relationship was not identical for the different tumor lines, suggesting that it was influenced by intrinsic properties of the tumor cells such as rate of respiration and ability to survive under hypoxia. Similarly, there was no correlation between bioenergetic status and fraction of radiobiologically hypoxic cells across the four tumor lines. This indicates that 31P-NMR spectroscopy data have to be supplemented with other data, e.g., rate of oxygen consumption, cell survival time under hypoxic stress, and/or fraction of metabolically active

  7. Determination of Irreducible Water Saturation from nuclear magnetic resonance based on fractal theory — a case study of sandstone with complex pore structure

    Science.gov (United States)

    Peng, L.; Pan, H.; Ma, H.; Zhao, P.; Qin, R.; Deng, C.

    2017-12-01

    The irreducible water saturation (Swir) is a vital parameter for permeability prediction and original oil and gas estimation. However, the complex pore structure of the rocks makes the parameter difficult to be calculated from both laboratory and conventional well logging methods. In this study, an effective statistical method to predict Swir is derived directly from nuclear magnetic resonance (NMR) data based on fractal theory. The spectrum of transversal relaxation time (T2) is normally considered as an indicator of pore size distribution, and the micro- and meso-pore's fractal dimension in two specific range of T2 spectrum distribution are calculated. Based on the analysis of the fractal characteristics of 22 core samples, which were drilled from four boreholes of tight lithologic oil reservoirs of Ordos Basin in China, the positive correlation between Swir and porosity is derived. Afterwards a predicting model for Swir based on linear regressions of fractal dimensions is proposed. It reveals that the Swir is controlled by the pore size and the roughness of the pore. The reliability of this model is tested and an ideal consistency between predicted results and experimental data is found. This model is a reliable supplementary to predict the irreducible water saturation in the case that T2 cutoff value cannot be accurately determined.

  8. A general model to calculate the spin-lattice (T1) relaxation time of blood, accounting for haematocrit, oxygen saturation and magnetic field strength.

    Science.gov (United States)

    Hales, Patrick W; Kirkham, Fenella J; Clark, Christopher A

    2016-02-01

    Many MRI techniques require prior knowledge of the T1-relaxation time of blood (T1bl). An assumed/fixed value is often used; however, T1bl is sensitive to magnetic field (B0), haematocrit (Hct), and oxygen saturation (Y). We aimed to combine data from previous in vitro measurements into a mathematical model, to estimate T1bl as a function of B0, Hct, and Y. The model was shown to predict T1bl from in vivo studies with a good accuracy (± 87 ms). This model allows for improved estimation of T1bl between 1.5-7.0 T while accounting for variations in Hct and Y, leading to improved accuracy of MRI-derived perfusion measurements. © The Author(s) 2015.

  9. Investigating the Role of Shell Thickness and Field Cooling on Saturation Magnetization and Its Temperature Dependence in Fe3O4/γ-Fe2O3 Core/Shell Nanoparticles

    Directory of Open Access Journals (Sweden)

    Ihab M. Obaidat

    2017-12-01

    Full Text Available Understanding saturation magnetization and its behavior with particle size and temperature are essential for medical applications such magnetic hyperthermia. We report the effect of shell thickness and field cooling on the saturation magnetization and its behavior with temperature in Fe3O4/γ-Fe2O3 core/shell nanoparticles of fixed core diameter (8 nm and several shell thicknesses. X-ray diffraction (XRD analysis and transmission electron microscopy (TEM, high-resolution transmission electron microscopy (HRTEM were used to investigate the phase and the morphology of the samples. Selected area electron diffraction (SAED confirmed the core/shell structure and phases. Using a SQUID (San Diego, CA, USA, magnetic measurements were conducted in the temperature range of 2 to 300 K both under zero field-cooling (ZFC and field-cooling (FC protocols at several field-cooling values. In the ZFC state, considerable enhancement of saturation magnetization was obtained with the increase of shell thickness. After field cooling, we observed a drastic enhancement of the saturation magnetization in one sample up to 120 emu/g (50% larger than the bulk value. In both the FC and ZFC states, considerable deviations from the original Bloch’s law were observed. These results are discussed and attributed to the existence of interface spin-glass clusters which are modified by the changes in the shell thickness and the field-cooling.

  10. Magnetic resonance enteroclysis in patients with Crohn's disease: fat saturated T2-weighted sequences for evaluation of inflammatory activity.

    Science.gov (United States)

    Grieser, Christian; Denecke, Timm; Steffen, Ingo G; Werner, Scarlett; Kröncke, Thomas; Guckelberger, Olaf; Pape, Ulrich-Frank; Meier, Johannes; Thiel, Regina; Kivelitz, Dietmar; Sturm, Andreas; Hamm, Bernd; Röttgen, Rainer

    2012-04-01

    To evaluate fat saturated (fs) T2-weighted (w) fast relaxation fast spin echo (FRFSE)-sequences compared to the standard protocol with contrast agent for the evaluation of inflammatory activity in patients with Crohn's Disease (CD). Fourty-eight patients (male, 17; female, 33; mean age, 37 years) with suspicion of inflammatory activity in proven CD who underwent MR enteroclysis (MRE) at 1.5T (GE Healthcare) were retrospectively included. Two blinded radiologists analyzed MRE images for presence and extent of CD lesions and degree of local inflammation for fsT2-w FRFSE and contrast enhanced T1-w images (T2-activity; T1-activity; score, 1-4) in consensus. Furthermore, mural signal intensity (SI) ratios (T2-ratio; T1-ratio) were recorded. Patient based MRE findings were correlated with endoscopic (45 patients), surgical (6 patients), histopathological, and clinical data (CDAI) as a surrogate reference standard. In total, 24 of 48 eligible patients presented with acute inflammatory activity with 123 affected bowel segments. ROC analysis of the total inflammatory score presented an AUC of 0.93 (pT2-activity (T1-activity, AUC 0.63; p=0.019). ROC analysis revealed an AUC of 0.76 (pT2-ratio (T1-ratio, AUC 0.51; p=0.93). General linear regression model revealed T2-activity (p=0.001) and age (p=0.024) as predictive factors of acute bowel inflammation. T2-w FRFSE-sequences can depict CD lesions and help to assess the inflammation activity, even with improved accuracy as compared to contrast-enhanced T1-w sequences. Copyright © 2011 European Crohn's and Colitis Organisation. Published by Elsevier B.V. All rights reserved.

  11. On-bead combinatorial synthesis and imaging of chemical exchange saturation transfer magnetic resonance imaging agents to identify factors that influence water exchange.

    Science.gov (United States)

    Napolitano, Roberta; Soesbe, Todd C; De León-Rodríguez, Luis M; Sherry, A Dean; Udugamasooriya, D Gomika

    2011-08-24

    The sensitivity of magnetic resonance imaging (MRI) contrast agents is highly dependent on the rate of water exchange between the inner sphere of a paramagnetic ion and bulk water. Normally, identifying a paramagnetic complex that has optimal water exchange kinetics is done by synthesizing and testing one compound at a time. We report here a rapid, economical on-bead combinatorial synthesis of a library of imaging agents. Eighty different 1,4,7,10-tetraazacyclododecan-1,4,7,10-tetraacetic acid (DOTA)-tetraamide peptoid derivatives were prepared on beads using a variety of charged, uncharged but polar, hydrophobic, and variably sized primary amines. A single chemical exchange saturation transfer image of the on-bead library easily distinguished those compounds having the most favorable water exchange kinetics. This combinatorial approach will allow rapid screening of libraries of imaging agents to identify the chemical characteristics of a ligand that yield the most sensitive imaging agents. This technique could be automated and readily adapted to other types of MRI or magnetic resonance/positron emission tomography agents as well.

  12. Fat suppression with short inversion time inversion-recovery and chemical-shift selective saturation: a dual STIR-CHESS combination prepulse for turbo spin echo pulse sequences.

    Science.gov (United States)

    Tanabe, Koji; Nishikawa, Keiichi; Sano, Tsukasa; Sakai, Osamu; Jara, Hernán

    2010-05-01

    To test a newly developed fat suppression magnetic resonance imaging (MRI) prepulse that synergistically uses the principles of fat suppression via inversion recovery (STIR) and spectral fat saturation (CHESS), relative to pure CHESS and STIR. This new technique is termed dual fat suppression (Dual-FS). To determine if Dual-FS could be chemically specific for fat, the phantom consisted of the fat-mimicking NiCl(2) aqueous solution, porcine fat, porcine muscle, and water was imaged with the three fat-suppression techniques. For Dual-FS and STIR, several inversion times were used. Signal intensities of each image obtained with each technique were compared. To determine if Dual-FS could be robust to magnetic field inhomogeneities, the phantom consisting of different NiCl(2) aqueous solutions, porcine fat, porcine muscle, and water was imaged with Dual-FS and CHESS at the several off-resonance frequencies. To compare fat suppression efficiency in vivo, 10 volunteer subjects were also imaged with the three fat-suppression techniques. Dual-FS could suppress fat sufficiently within the inversion time of 110-140 msec, thus enabling differentiation between fat and fat-mimicking aqueous structures. Dual-FS was as robust to magnetic field inhomogeneities as STIR and less vulnerable than CHESS. The same results for fat suppression were obtained in volunteers. The Dual-FS-STIR-CHESS is an alternative and promising fat suppression technique for turbo spin echo MRI. Copyright 2010 Wiley-Liss, Inc.

  13. Proton magnetic resonance studies of 5,6-saturated thymidine derivatives produced by ionizing radiation. Conformational analysis of 6-hydroxylated diastereoisomers

    Energy Technology Data Exchange (ETDEWEB)

    Cadet, J; Ducolomb, R [CEA Centre d' Etudes Nucleaires de Grenoble, 38 (France). Lab. de Radiobiologie; Hruska, F E [Manitoba Univ., Winnipeg (Canada). Dept. of Chemistry

    1979-06-20

    The conformational properties of ten 6-hydroxylated dihydrothymidine derivatives including the various diastereoisomers of 5,6-dihydroxy-5,6-dihydrothymidine, 6-hydroxy-5,6-dihydrothymidine and 5-bromo-6-hydroxy-5,6-dihydrothymidine have been studied by 250 MHz proton magnetic resonance in aqueous solutions. A close correlation has been established between the carbon-6 configuration and the osidic conformation. The increase in the amplitude of the puckering within the furanose ring compared to that of thymidine or 2'-deoxyuridine is more pronounced for the levortatory (6S) nucleosides than for the dextrorotatory (6R) diastereoisomers. The importance of the 2'endo conformer population decreases in the following order: (-)> (+)>thymidine. The absence of destabilizing effects on the g/sup +/ rotameric population about the C(4')-C(5') bond denotes the lack of any interaction between exocyclic hydroxymethyl group and the 6-hydroxyl function or the 2-keto group. The 5,6-saturated nucleosides adopt a preferential anti conformation. The comparison has been extended to syn nucleosides which show opposite trends in the sugar conformation and g/sup +/ distribution.

  14. Saturation of the turbulent dynamo.

    Science.gov (United States)

    Schober, J; Schleicher, D R G; Federrath, C; Bovino, S; Klessen, R S

    2015-08-01

    The origin of strong magnetic fields in the Universe can be explained by amplifying weak seed fields via turbulent motions on small spatial scales and subsequently transporting the magnetic energy to larger scales. This process is known as the turbulent dynamo and depends on the properties of turbulence, i.e., on the hydrodynamical Reynolds number and the compressibility of the gas, and on the magnetic diffusivity. While we know the growth rate of the magnetic energy in the linear regime, the saturation level, i.e., the ratio of magnetic energy to turbulent kinetic energy that can be reached, is not known from analytical calculations. In this paper we present a scale-dependent saturation model based on an effective turbulent resistivity which is determined by the turnover time scale of turbulent eddies and the magnetic energy density. The magnetic resistivity increases compared to the Spitzer value and the effective scale on which the magnetic energy spectrum is at its maximum moves to larger spatial scales. This process ends when the peak reaches a characteristic wave number k☆ which is determined by the critical magnetic Reynolds number. The saturation level of the dynamo also depends on the type of turbulence and differs for the limits of large and small magnetic Prandtl numbers Pm. With our model we find saturation levels between 43.8% and 1.3% for Pm≫1 and between 2.43% and 0.135% for Pm≪1, where the higher values refer to incompressible turbulence and the lower ones to highly compressible turbulence.

  15. Non-invasive investigation of the saturated/unsaturated zone with magnetic resonance sounding - a field example at the testsite Fuhrberger Feld near Hannover, Germany

    Science.gov (United States)

    Costabel, S.; Noell, U.; Ganz, C.

    2012-04-01

    Magnetic resonance sounding (MRS) is a non-invasive geophysical method for groundwater prospection that uses the principle of nuclear magnetic resonance (NMR) in the Earth's magnetic field. Its unique property distinct from other hydrogeophysical methods is the direct sensitivity to the amount of water, i.e. to the amount of 1H nuclei in the subsurface. Because MRS is normally used to investigate the water content of the saturated zone and to characterize aquifer structures, the standard application is optimized for 1D-measurements in depths from several to several tens of meters. However, our investigations show that MRS has also the potential to contribute substantially to the study of groundwater recharge if the sensitivity of the method for the unsaturated zone and for the transition to the saturated zone is increased by using a modified measurement setup and adjusted interpretation schemes. We conducted MRS test measurements with the focus on the very shallow subsurface in the range of some few decimeters down to the groundwater table in a depth of 3 m. The test site is located in the area Fuhrberger Feld about 30 km north-east of Hannover, Germany, which comprises an unconfined sandy aquifer of 20 to 30-m thickness. Previous studies have discovered the soil physical characteristics of the site with tension infiltrometer measurements and tracer irrigation experiments in the field, as well as with water retention measurements in the laboratory. In addition, several infiltration experiments with dye tracer were conducted and monitored with electrical resistivity tomography (ERT), tensiometers and TDR devices. For the MRS measurements at the testsite, a serious challenge was the intense electromagnetic noise consisting of large spiky radio signals and harmonic components, respectively. A special combination of new processing techniques was developed to isolate and interpret the NMR signals with amplitudes of approximately 5 to 14 nV. The standard inversion of the

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

    Science.gov (United States)

    Buehler, Tania; Kreis, Roland; Boesch, Chris

    2015-02-01

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

  17. Influence of amplitude-related perfusion parameters in the parotid glands by non-fat-saturated dynamic contrast-enhanced magnetic resonance imaging

    International Nuclear Information System (INIS)

    Chiu, Su-Chin; Cheng, Cheng-Chieh; Chang, Hing-Chiu; Chung, Hsiao-Wen; Chiu, Hui-Chu; Liu, Yi-Jui; Hsu, Hsian-He; Juan, Chun-Jung

    2016-01-01

    Purpose: To verify whether quantification of parotid perfusion is affected by fat signals on non-fat-saturated (NFS) dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and whether the influence of fat is reduced with fat saturation (FS). Methods: This study consisted of three parts. First, a retrospective study analyzed DCE-MRI data previously acquired on different patients using NFS (n = 18) or FS (n = 18) scans. Second, a phantom study simulated the signal enhancements in the presence of gadolinium contrast agent at six concentrations and three fat contents. Finally, a prospective study recruited nine healthy volunteers to investigate the influence of fat suppression on perfusion quantification on the same subjects. Parotid perfusion parameters were derived from NFS and FS DCE-MRI data using both pharmacokinetic model analysis and semiquantitative parametric analysis. T tests and linear regression analysis were used for statistical analysis with correction for multiple comparisons. Results: NFS scans showed lower amplitude-related parameters, including parameter A, peak enhancement (PE), and slope than FS scans in the patients (all with P < 0.0167). The relative signal enhancement in the phantoms was proportional to the dose of contrast agent and was lower in NFS scans than in FS scans. The volunteer study showed lower parameter A (6.75 ± 2.38 a.u.), PE (42.12% ± 14.87%), and slope (1.43% ± 0.54% s"−"1) in NFS scans as compared to 17.63 ± 8.56 a.u., 104.22% ± 25.15%, and 9.68% ± 1.67% s"−"1, respectively, in FS scans (all with P < 0.005). These amplitude-related parameters were negatively associated with the fat content in NFS scans only (all with P < 0.05). Conclusions: On NFS DCE-MRI, quantification of parotid perfusion is adversely affected by the presence of fat signals for all amplitude-related parameters. The influence could be reduced on FS scans.

  18. Influence of amplitude-related perfusion parameters in the parotid glands by non-fat-saturated dynamic contrast-enhanced magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, Su-Chin [Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei 106, Taiwan, Republic of China and Department of Radiology, Tri-Service General Hospital, Taipei 114, Taiwan (China); Cheng, Cheng-Chieh [Department of Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts 02115 (United States); Chang, Hing-Chiu [Department of Diagnostic Radiology, The University of Hong Kong (Hong Kong); Chung, Hsiao-Wen [Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei 106, Taiwan (China); Department of Radiology, Tri-Service General Hospital, Taipei 114, Taiwan (China); Department of Radiology, National Defense Medical Center, Taipei 114, Taiwan (China); Chiu, Hui-Chu [Ph.D. Program of Technology Management, Chung Hua University, Hsinchu 300, Taiwan (China); Liu, Yi-Jui [Department of Automatic Control Engineering, Feng-Chia University, Taichung 407, Taiwan (China); Hsu, Hsian-He; Juan, Chun-Jung, E-mail: peterjuancj@yahoo.com.tw [Department of Radiology, Tri-Service General Hospital, Taipei 114, Taiwan and Department of Radiology, National Defense Medical Center, Taipei 114, Taiwan (China)

    2016-04-15

    Purpose: To verify whether quantification of parotid perfusion is affected by fat signals on non-fat-saturated (NFS) dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and whether the influence of fat is reduced with fat saturation (FS). Methods: This study consisted of three parts. First, a retrospective study analyzed DCE-MRI data previously acquired on different patients using NFS (n = 18) or FS (n = 18) scans. Second, a phantom study simulated the signal enhancements in the presence of gadolinium contrast agent at six concentrations and three fat contents. Finally, a prospective study recruited nine healthy volunteers to investigate the influence of fat suppression on perfusion quantification on the same subjects. Parotid perfusion parameters were derived from NFS and FS DCE-MRI data using both pharmacokinetic model analysis and semiquantitative parametric analysis. T tests and linear regression analysis were used for statistical analysis with correction for multiple comparisons. Results: NFS scans showed lower amplitude-related parameters, including parameter A, peak enhancement (PE), and slope than FS scans in the patients (all with P < 0.0167). The relative signal enhancement in the phantoms was proportional to the dose of contrast agent and was lower in NFS scans than in FS scans. The volunteer study showed lower parameter A (6.75 ± 2.38 a.u.), PE (42.12% ± 14.87%), and slope (1.43% ± 0.54% s{sup −1}) in NFS scans as compared to 17.63 ± 8.56 a.u., 104.22% ± 25.15%, and 9.68% ± 1.67% s{sup −1}, respectively, in FS scans (all with P < 0.005). These amplitude-related parameters were negatively associated with the fat content in NFS scans only (all with P < 0.05). Conclusions: On NFS DCE-MRI, quantification of parotid perfusion is adversely affected by the presence of fat signals for all amplitude-related parameters. The influence could be reduced on FS scans.

  19. Enhanced saturation magnetization of Fe{sub 3}Si nanodot-embedded Fe{sub 80}Si{sub 17}Nb{sub 3} flexible film for efficient wireless power transfer

    Energy Technology Data Exchange (ETDEWEB)

    Pai, Yi-Hao, E-mail: paiyihao@mail.ndhu.edu.tw; Yan, Zih-Yu; Fu, Ping-Hao

    2013-07-15

    An efficient magnetically coupled resonance response is performed using an iron silicide-based nanostructured magnetoelectric material with high saturation magnetization for the wireless charging of battery-powered consumer electronics. With 500 °C annealing, the self-assembled Fe{sub 3}Si nanodots buried in the Fe{sub 80}Si{sub 17}Nb{sub 3} host matrix with (220) lattice spacing of 1.99 Å corresponding to a volume density of 8.96 × 10{sup 16} cm{sup 3}, can be obtained and a maximum saturation magnetization of 244 emu g{sup −1} achieved. The return loss of the antenna will be tuned to match the designed frequency with greater attenuated intensity (−0.39 dB) and a relatively narrow bandwidth (6 kHz) when the Fe{sub 3}Si nanodot-embedded Fe{sub 80}Si{sub 17}Nb{sub 3} sample is placed in a WiTricity system. An efficient wireless power transfer can be created and improved from 47.5% to 97.3%. The associated coil and loop antenna resonators are significantly readjusted to match the power transfer by putting this nanostructured magnetoelectric material in a WiTricity system. - Highlights: • The saturation magnetization is effective enhancement in the presence of Fe{sub 3}Si nanodot buried in the Fe{sub 80}Si{sub 17}Nb{sub 3}. • A saturation magnetization of 244 emu g{sup −1} is proposed for high-efficiency wireless power transfer. • The return loss of the antenna will be tuned to match the designed frequency. • Such a wireless power transfer can be enhanced efficiency up to 97.3%.

  20. Off-resonance R1ρ relaxation outside of the fast exchange limit: An experimental study of a cavity mutant of T4 lysozyme

    International Nuclear Information System (INIS)

    Korzhnev, Dmitry M.; Orekhov, Vladislav Yu.; Dahlquist, Frederick W.; Kay, Lewis E.

    2003-01-01

    An 15 N off-resonance R 1ρ spin relaxation study of an L99A point mutant of T4 lysozyme is presented. Previous CPMG-based relaxation dispersion studies of exchange in this protein have established that the molecule interconverts between a populated ground state and an excited state (3.4%) with an exchange rate constant of 1450 s -1 at 25 deg. C. It is shown that for the majority of residues in this protein the offset dependence of the R 1ρ relaxation rates cannot be well fit using models which are only valid in the fast exchange regime. In contrast, a recently derived expression by Trott and Palmer (J. Magn. Reson., 154, 157-160, 2002) which is valid over a wider window of exchange than other relations, is shown to fit the data well. Values of (signed) chemical shift differences between exchanging sites have been extracted and are in reasonable agreement with shift differences measured using CPMG methods. A set of simulations is presented which help establish the exchange regimes that are best suited to analysis by off-resonance R 1ρ techniques

  1. Assessing atmospheric particulate matter distribution based on Saturation Isothermal Remanent Magnetization of herbaceous and tree leaves in a tropical urban environment.

    Science.gov (United States)

    Barima, Yao Sadaiou Sabas; Angaman, Djédoux Maxime; N'gouran, Kobenan Pierre; Koffi, N'guessan Achille; Kardel, Fatemeh; De Cannière, Charles; Samson, Roeland

    2014-02-01

    Particulate matter (PM) emissions, and the associated human health risks, are likely to continue increasing in urban environments of developing countries like Abidjan (Ivory Cost). This study evaluated the potential of leaves of several herbaceous and tree species as bioindicators of urban particulate matter pollution, and its variation over different land use classes, in a tropical area. Four species well distributed (presence frequencies >90%) over all land use classes, easy to harvest and whose leaves are wide enough to be easily scanned were selected, i.e.: Amaranthus spinosus (Amaranthaceae), Eleusine indica (Poaceae), Panicum maximum (Poaceae) and Ficus benjamina (Moraceae). Leaf sampling of these species was carried out at 3 distances from the road and at 3 height levels. Traffic density was also noted and finally biomagnetic parameters of these leaves were determined. Results showed that Saturation Isothermal Remanent Magnetization (SIRM) of leaves was at least 4 times higher (27.5×10(-6)A) in the vicinity of main roads and industrial areas than in parks and residential areas. The main potential sources of PM pollution were motor vehicles and industries. The slightly hairy leaves of the herbaceous plant A. spinosus and the waxy leaves of the tree F. benjamina showed the highest SIRM (25×10(-6)A). Leaf SIRM increased with distance to road (R(2)>0.40) and declined with sampling height (R(2)=0.17). The distance between 0 and 5m from the road seemed to be the most vulnerable in terms of PM pollution. This study has showed that leaf SIRM of herbaceous and tree species can be used to assess PM exposure in tropical urban environments. © 2013.

  2. Suppression of error in qubit rotations due to Bloch-Siegert oscillation via the use of off-resonant Raman excitation

    International Nuclear Information System (INIS)

    Pradhan, Prabhakar; Cardoso, George C; Shahriar, M S

    2009-01-01

    The rotation of a quantum bit (qubit) is an important step in quantum computation. The rotation is generally performed using a Rabi oscillation. In a direct two-level qubit system, if the Rabi frequency is comparable to its resonance frequency, the rotating wave approximation is not valid, and the Rabi oscillation is accompanied by the so-called Bloch-Siegert oscillation (BSO) that occurs at twice the frequency of the driving field. One implication of the BSO is that for a given interaction time and Rabi frequency, the degree of rotation experienced by the qubit depends explicitly on the initial phase of the driving field. If this effect is not controlled, it leads to an apparent fluctuation in the rotation of the qubit. Here we show that when an off-resonant lambda system is used to realize a two-level qubit, the BSO is inherently negligible, thus eliminating this source of potential error.

  3. Off-resonance rotating-frame relaxation dispersion experiment for 13C in aromatic side chains using L-optimized TROSY-selection

    DEFF Research Database (Denmark)

    Weininger, Ulrich; Brath, Ulrika; Modig, Kristofer

    2014-01-01

    Protein dynamics on the microsecond-millisecond time scales often play a critical role in biological function. NMR relaxation dispersion experiments are powerful approaches for investigating biologically relevant dynamics with site-specific resolution, as shown by a growing number of publications...... on enzyme catalysis, protein folding, ligand binding, and allostery. To date, the majority of studies has probed the backbone amides or side-chain methyl groups, while experiments targeting other sites have been used more sparingly. Aromatic side chains are useful probes of protein dynamics, because...... they are over-represented in protein binding interfaces, have important catalytic roles in enzymes, and form a sizable part of the protein interior. Here we present an off-resonance R 1ρ experiment for measuring microsecond to millisecond conformational exchange of aromatic side chains in selectively (13)C...

  4. The application of "double isolation" in Fourier transform ion cyclotron resonance sustained off-resonance irradiation collisionally-induced dissociation tandem mass spectrometry to remove labile isobaric impurities.

    Science.gov (United States)

    Gates, Paul J; Lopes, Norberto P; Pinto, Emani; Colepicolo, Pio; Cardozo, Karina H M

    2011-01-01

    This study reports the application of "double isolation" in sustained off-resonance irradiation collisionally-induced dissociation tandem mass spectrometry (SORI-CID-MS/MS) to remove radio- frequency (RF) fragment ions of very close mass isobaric ions (0.02 m/z apart). Analyses were performed with a fraction of a biological extract isolated from a macroalgae containing the mycosporine-like amino acid asterina-330. Direct isolation of the precursor ion by narrowing the isolation window proved ineffective as it impinged upon the required ion thus substantially reducing its intensity. By increasing the correlated sweep time, ejection efficiency of the isolation was improved, but caused the unwanted side-effect of RF fragmentation of labile ions. Finally, by skipping the ion activation step and performing a second isolation (in the MS(3) module) the RF fragments from the first isolation were removed leaving a very pure isolation of the required precursor ion and allowed a very clean CID fragmentation. We demonstrated that the m/z 272.1351 ion is derived from the loss of NH(3) from m/z 289.1620 isobaric impurity and is not related to asterina-330. This application represents a powerful tool to remove unwanted ions in the MS/MS spectrum that result from fragmentation of isobaric ions.

  5. Phase collapse and revival of a 1-mode Bose-Einstein condensate induced by an off-resonant optical probe field and superselection rules

    Science.gov (United States)

    Arruda, L. G. E.; Prataviera, G. A.; de Oliveira, M. C.

    2018-02-01

    Phase collapse and revival for Bose-Einstein condensates are nonlinear phenomena appearing due to atomic collisions. While it has been observed in a general setting involving many modes, for one-mode condensates its occurrence is forbidden by the particle number superselection rule (SSR), which arises because there is no phase reference available. We consider a single mode atomic Bose-Einstein condensate interacting with an off-resonant optical probe field. We show that the condensate phase revival time is dependent on the atom-light interaction, allowing optical control on the atomic collapse and revival dynamics. Incoherent effects over the condensate phase are included by considering a continuous photo-detection over the probe field. We consider conditioned and unconditioned photo-counting events and verify that no extra control upon the condensate is achieved by the probe photo-detection, while further inference of the atomic system statistics is allowed leading to a useful test of the SSR on particle number and its imposition on the kind of physical condensate state.

  6. Saturated tearing modes in tokamaks with divertors

    International Nuclear Information System (INIS)

    Bateman, G.

    1982-12-01

    We have developed a self-consistent theory of saturated tearing modes capable of predicting multiple magnetic island widths in tokamaks with no assumptions on the cross-sectional shape, aspect ratio, or plasma pressure. We are in the process of implementing this algorithm in the form of a computer code. We propose: (1) to complete, refine, document and publish this computer code; (2) to carry out a survey in which we vary the current profile, aspect ratio, cross-sectional shape, and pressure profile in order to determine their effect on saturated tearing mode magnetic island widths; and (3) to determine the effect of some externally applied magnetic perturbation harmonics on these magnetic island widths. Particular attention will be paid to the coupling between different helical harmonics, the effect of multiple magnetic islands on the profiles of temperature, pressure and current, and the potential of magnetic island overlap leading to a disruptive instability

  7. Saturated Switching Systems

    CERN Document Server

    Benzaouia, Abdellah

    2012-01-01

    Saturated Switching Systems treats the problem of actuator saturation, inherent in all dynamical systems by using two approaches: positive invariance in which the controller is designed to work within a region of non-saturating linear behaviour; and saturation technique which allows saturation but guarantees asymptotic stability. The results obtained are extended from the linear systems in which they were first developed to switching systems with uncertainties, 2D switching systems, switching systems with Markovian jumping and switching systems of the Takagi-Sugeno type. The text represents a thoroughly referenced distillation of results obtained in this field during the last decade. The selected tool for analysis and design of stabilizing controllers is based on multiple Lyapunov functions and linear matrix inequalities. All the results are illustrated with numerical examples and figures many of them being modelled using MATLAB®. Saturated Switching Systems will be of interest to academic researchers in con...

  8. Interaction between Wine Phenolic Acids and Salivary Proteins by Saturation-Transfer Difference Nuclear Magnetic Resonance Spectroscopy (STD-NMR) and Molecular Dynamics Simulations.

    Science.gov (United States)

    Ferrer-Gallego, Raúl; Hernández-Hierro, José Miguel; Brás, Natércia F; Vale, Nuno; Gomes, Paula; Mateus, Nuno; de Freitas, Victor; Heredia, Francisco J; Escribano-Bailón, María Teresa

    2017-08-09

    The interaction between phenolic compounds and salivary proteins is highly related to the astringency perception. Recently, it has been proven the existence of synergisms on the perceived astringency when phenolic acids were tested as mixtures in comparison to individual compounds, maintaining constant the total amount of the stimulus. The interactions between wine phenolic acids and the peptide fragment IB7 12 have been studied by saturation-transfer difference (STD) NMR spectroscopy. This technique provided the dissociation constants and the percentage of interaction between both individual and mixtures of hydroxybenzoic and hydroxycinnamic acids and the model peptide. It is noteworthy that hydroxybenzoic acids showed higher affinity for the peptide than hydroxycinnamic acids. To obtain further insights into the mechanisms of interaction, molecular dynamics simulations have been performed. Results obtained not only showed the ability of these compounds to interact with salivary proteins but also may justify the synergistic effect observed in previous sensory studies.

  9. Evaluating the Uncertainty in Exchange Parameters Determined from Off-Resonance R1ρ Relaxation Dispersion for Systems in Fast Exchange

    Science.gov (United States)

    Bothe, Jameson R.; Stein, Zachary W.; Al-Hashimi, Hashim M.

    2014-01-01

    Spin relaxation in the rotating frame (R1ρ) is a powerful NMR technique for characterizing fast microsecond timescale exchange processes directed toward short-lived excited states in biomolecules. At the limit of fast exchange, only kex = k1 + k−1 and Φıx = pGpE(Δω)2 can be determined from R1ρ data limiting the ability to characterize the structure and energetics of the excited state conformation. Here, we use simulations to examine the uncertainty with which exchange parameters can be determined for two state systems in intermediate-to-fast exchange using off-resonance R1ρ relaxation dispersion. R1ρ data computed by solving the Bloch-McConnell equations reveals small but significant asymmetry with respect to offset (R1ρ(ΔΩ) ≠ R1ρ(−ΔΩ)), which is a hallmark of slow-to-intermediate exchange, even under conditions of fast exchange for free precession chemical exchange line broadening (kex/Δω > 10). A grid search analysis combined with bootstrap and Monte-Carlo based statistical approaches for estimating uncertainty in exchange parameters reveals that both the sign and magnitude of Δω can be determined at a useful level of uncertainty for systems in fast exchange (kex/Δω exchange parameters. Results from simulations are complemented by analysis of experimental R1ρ data measured in three nucleic acid systems with exchange processes occurring on the slow (kex/Δω = 0.2; pE = ~ 0.7%), fast (kex/Δω = ~10–16; pE = ~13%) and very fast (kex = 39,000 s−1) chemical shift timescales. PMID:24819426

  10. Magnetic resonance imaging of articular cartilage in the knee. Evaluation of 3D-fat-saturation FLASH sequence in normal volunteer and patient with osteoarthritis

    International Nuclear Information System (INIS)

    Sato, Katsuhiko

    1996-01-01

    MR imaging of normal and abnormal articular cartilage of the knee was performed using 3D-fat-saturation FLASH sequence (FSF). Contrast-to-noise ratios between the cartilage and fluid, and cartilage and bone marrow were evaluated respectively in 10 normal volunteers. The optimal imaging parameters were determined as flip angle of 40deg and TE of 10 ms. Good correlation was noted between MR images and macroscopic appearance of the hyaline cartilages in the cadaver knees. Comparison of MR and radiographic findings was made in 39 cases of osteoarthritis. MR was significantly more sensitive than radiography in detecting cartilage abnormalities. In patient with radiographically normal joint spaces, cartilage abnormality was detected by MRI in the medial compartment of 13 cases and the lateral compartment of 19 cases. Signal intensity of joint effusion was sufficiently suppressed and did not hamper evaluation of the cartilages. FSF method was considered as a valuable imaging technique in the evaluation of cartilage abnormalities of the knee. (author)

  11. Magnetic resonance imaging of articular cartilage in the knee. Evaluation of 3D-fat-saturation FLASH sequence in normal volunteer and patient with osteoarthritis

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Katsuhiko [Kyorin Univ., Mitaka, Tokyo (Japan). School of Medicine

    1996-07-01

    MR imaging of normal and abnormal articular cartilage of the knee was performed using 3D-fat-saturation FLASH sequence (FSF). Contrast-to-noise ratios between the cartilage and fluid, and cartilage and bone marrow were evaluated respectively in 10 normal volunteers. The optimal imaging parameters were determined as flip angle of 40deg and TE of 10 ms. Good correlation was noted between MR images and macroscopic appearance of the hyaline cartilages in the cadaver knees. Comparison of MR and radiographic findings was made in 39 cases of osteoarthritis. MR was significantly more sensitive than radiography in detecting cartilage abnormalities. In patient with radiographically normal joint spaces, cartilage abnormality was detected by MRI in the medial compartment of 13 cases and the lateral compartment of 19 cases. Signal intensity of joint effusion was sufficiently suppressed and did not hamper evaluation of the cartilages. FSF method was considered as a valuable imaging technique in the evaluation of cartilage abnormalities of the knee. (author)

  12. Gluon saturation in a saturated environment

    International Nuclear Information System (INIS)

    Kopeliovich, B. Z.; Potashnikova, I. K.; Schmidt, Ivan

    2011-01-01

    A bootstrap equation for self-quenched gluon shadowing leads to a reduced magnitude of broadening for partons propagating through a nucleus. Saturation of small-x gluons in a nucleus, which has the form of transverse momentum broadening of projectile gluons in pA collisions in the nuclear rest frame, leads to a modification of the parton distribution functions in the beam compared with pp collisions. In nucleus-nucleus collisions all participating nucleons acquire enhanced gluon density at small x, which boosts further the saturation scale. Solution of the reciprocity equations for central collisions of two heavy nuclei demonstrate a significant, up to several times, enhancement of Q sA 2 , in AA compared with pA collisions.

  13. Automatic NAA. Saturation activities

    International Nuclear Information System (INIS)

    Westphal, G.P.; Grass, F.; Kuhnert, M.

    2008-01-01

    A system for Automatic NAA is based on a list of specific saturation activities determined for one irradiation position at a given neutron flux and a single detector geometry. Originally compiled from measurements of standard reference materials, the list may be extended also by the calculation of saturation activities from k 0 and Q 0 factors, and f and α values of the irradiation position. A systematic improvement of the SRM approach is currently being performed by pseudo-cyclic activation analysis, to reduce counting errors. From these measurements, the list of saturation activities is recalculated in an automatic procedure. (author)

  14. Effect of collagen on magnetization transfer contrast assessed in cultured cartilage

    International Nuclear Information System (INIS)

    Aoki, Jun; Seo, Gwy-Suk; Karakida, Osamu; Ueda, Hitoshi; Sone, Shusuke; Hiraki, Yuji; Shukunami, Chisa; Moriya, Hiroto.

    1996-01-01

    We investigated the effect of collagen on magnetization transfer contrast (MTC) in cultured cartilage. In our culture system, only collagen synthesis was increased by the addition of vitamin C, while proteoglycan synthesis and the number of chondrocytes were unaffected. The MTC effect was assessed by using an off-resonance RF pulse (0.3 KHz off-resonance, sinc wave of 18 msec, maximum amplitude 4.61 x 10 -4 T) on a GRASS sequence. The cartilage cultured with vitamin C showed a higher MTC effect than that cultured without vitamin C. The major role of collagen on MTC was confirmed in living cartilage tissue. (author)

  15. Qualitative and quantitative comparison of contrast-enhanced fluid-attenuated inversion recovery, magnetization transfer spin echo, and fat-saturation T1-weighted sequences in infectious meningitis

    International Nuclear Information System (INIS)

    Azad, Rajiv; Tayal, Mohit; Azad, Sheenam; Sharma, Garima; Srivastava, Rajendra Kumar

    2017-01-01

    To compare the contrast-enhanced fluid-attenuated inversion recovery (CE-FLAIR), the CE T1-weighted (CE-T1W) sequence with fat suppression (FS) and magnetization transfer (MT) for early detection and characterization of infectious meningitis. Fifty patients and 10 control subjects were evaluated with the CE-FLAIR and the CE-T1W sequences with FS and MT. Qualitative assessment was done by two observers for presence and grading of abnormal leptomeningeal enhancement. Quantitative assessment included computation of net meningeal enhancement, using single pixel signal intensity software. A newly devised FLAIR based scoring system, based on certain imaging features including ventricular dilatation, ependymal enhancement, infarcts and subdural effusions was used to indicate the etiology. Data were analysed using the Student's t test, Cohen's Kappa coefficient, Pearson's correlation coefficient, the intraclass correlation coefficient, one way analysis of variance, and Fisher's exact test with Bonferroni correction as the post hoc test. The CE-FLAIR sequence demonstrated a better sensitivity (100%), diagnostic accuracy (95%), and a stronger correlation with the cerebrospinal fluid, total leukocyte count (r = 0.75), protein (r = 0.77), adenosine deaminase (r = 0.81) and blood glucose (r = -0.6) values compared to the CE-T1W sequences. Qualitative grades and quantitative meningeal enhancement on the CE-FLAIR sequence were also significantly greater than those on the other sequences. The FLAIR based scoring system yielded a diagnostic accuracy of 91.6% and a sensitivity of 96%. A strong inverse Pearson's correlation (r = -0.95) was found between the assigned score and patient's Glasgow Coma Scale at the time of admission. The CE-FLAIR sequence is better suited for evaluating infectious meningitis and could be included as a part of the routine MR imaging protocol

  16. Qualitative and quantitative comparison of contrast-enhanced fluid-attenuated inversion recovery, magnetization transfer spin echo, and fat-saturation T1-weighted sequences in infectious meningitis

    Energy Technology Data Exchange (ETDEWEB)

    Azad, Rajiv; Tayal, Mohit; Azad, Sheenam; Sharma, Garima; Srivastava, Rajendra Kumar [SGRR Institute of Medical and Health Sciences, Patel Nagar, Dehradun (India)

    2017-11-15

    To compare the contrast-enhanced fluid-attenuated inversion recovery (CE-FLAIR), the CE T1-weighted (CE-T1W) sequence with fat suppression (FS) and magnetization transfer (MT) for early detection and characterization of infectious meningitis. Fifty patients and 10 control subjects were evaluated with the CE-FLAIR and the CE-T1W sequences with FS and MT. Qualitative assessment was done by two observers for presence and grading of abnormal leptomeningeal enhancement. Quantitative assessment included computation of net meningeal enhancement, using single pixel signal intensity software. A newly devised FLAIR based scoring system, based on certain imaging features including ventricular dilatation, ependymal enhancement, infarcts and subdural effusions was used to indicate the etiology. Data were analysed using the Student's t test, Cohen's Kappa coefficient, Pearson's correlation coefficient, the intraclass correlation coefficient, one way analysis of variance, and Fisher's exact test with Bonferroni correction as the post hoc test. The CE-FLAIR sequence demonstrated a better sensitivity (100%), diagnostic accuracy (95%), and a stronger correlation with the cerebrospinal fluid, total leukocyte count (r = 0.75), protein (r = 0.77), adenosine deaminase (r = 0.81) and blood glucose (r = -0.6) values compared to the CE-T1W sequences. Qualitative grades and quantitative meningeal enhancement on the CE-FLAIR sequence were also significantly greater than those on the other sequences. The FLAIR based scoring system yielded a diagnostic accuracy of 91.6% and a sensitivity of 96%. A strong inverse Pearson's correlation (r = -0.95) was found between the assigned score and patient's Glasgow Coma Scale at the time of admission. The CE-FLAIR sequence is better suited for evaluating infectious meningitis and could be included as a part of the routine MR imaging protocol.

  17. Brain oxygen saturation assessment in neonates using T2-prepared blood imaging of oxygen saturation and near-infrared spectroscopy

    DEFF Research Database (Denmark)

    Alderliesten, Thomas; De Vis, Jill B; Lemmers, Petra Ma

    2017-01-01

    saturation in the sagittal sinus (R(2 )= 0.49, p = 0.023), but no significant correlations could be demonstrated with frontal and whole brain cerebral blood flow. These results suggest that measuring oxygen saturation by T2-prepared blood imaging of oxygen saturation is feasible, even in neonates. Strong...... sinus. A strong linear relation was found between the oxygen saturation measured by magnetic resonance imaging and the oxygen saturation measured by near-infrared spectroscopy (R(2 )= 0.64, p ..., and magnetic resonance imaging measures of frontal cerebral blood flow, whole brain cerebral blood flow and venous oxygen saturation in the sagittal sinus (R(2 )= 0.71, 0.50, 0.65; p 

  18. Gluon Saturation and EIC

    Energy Technology Data Exchange (ETDEWEB)

    Sichtermann, Ernst

    2016-12-15

    The fundamental structure of nucleons and nuclear matter is described by the properties and dynamics of quarks and gluons in quantum chromodynamics. Electron-nucleon collisions are a powerful method to study this structure. As one increases the energy of the collisions, the interaction process probes regions of progressively higher gluon density. This density must eventually saturate. An high-energy polarized Electron-Ion Collider (EIC) has been proposed to observe and study the saturated gluon density regime. Selected measurements will be discussed, following a brief introduction.

  19. Quantitative magnetization transfer imaging of rodent glioma using selective inversion recovery.

    Science.gov (United States)

    Xu, Junzhong; Li, Ke; Zu, Zhongliang; Li, Xia; Gochberg, Daniel F; Gore, John C

    2014-03-01

    Magnetization transfer (MT) provides an indirect means to detect noninvasively variations in macromolecular contents in biological tissues, but, so far, there have been only a few quantitative MT (qMT) studies reported in cancer, all of which used off-resonance pulsed saturation methods. This article describes the first implementation of a different qMT approach, selective inversion recovery (SIR), for the characterization of tumor in vivo using a rodent glioma model. The SIR method is an on-resonance method capable of fitting qMT parameters and T1 relaxation time simultaneously without mapping B0 and B1 , which is very suitable for high-field qMT measurements because of the lower saturation absorption rate. The results show that the average pool size ratio (PSR, the macromolecular pool versus the free water pool) in rat 9 L glioma (5.7%) is significantly lower than that in normal rat gray matter (9.2%) and white matter (17.4%), which suggests that PSR is potentially a sensitive imaging biomarker for the assessment of brain tumor. Despite being less robust, the estimated MT exchange rates also show clear differences from normal tissues (19.7 Hz for tumors versus 14.8 and 10.2 Hz for gray and white mater, respectively). In addition, the influence of confounding effects, e.g. B1 inhomogeneity, on qMT parameter estimates is investigated with numerical simulations. These findings not only help to better understand the changes in the macromolecular contents of tumors, but are also important for the interpretation of other imaging contrasts, such as chemical exchange saturation transfer of tumors. Copyright © 2013 John Wiley & Sons, Ltd.

  20. On the importance of exchangeable NH protons in creatine for the magnetic coupling of creatine methyl protons in skeletal muscle

    NARCIS (Netherlands)

    Kruiskamp, M.J.; Nicolaij, K.

    2001-01-01

    The methyl protons of creatine in skeletal muscle exhibit a strong off-resonance magnetization transfer effect. The mechanism of this process is unknown. We previously hypothesized that the exchangeable amide/amino protons of creatine might be involved. To test this the characteristics of the

  1. Magnets

    International Nuclear Information System (INIS)

    Young, I.R.

    1984-01-01

    A magnet pole piece for an NMR imaging magnet is made of a plurality of magnetic wires with one end of each wire held in a non-magnetic spacer, the other ends of the wires being brought to a pinch, and connected to a magnetic core. The wires may be embedded in a synthetic resin and the magnetisation and uniformity thereof can be varied by adjusting the density of the wires at the spacer which forms the pole piece. (author)

  2. Magnetization transfer ratio for the assessment of perianal fistula activity in Crohn's disease

    Energy Technology Data Exchange (ETDEWEB)

    Pinson, C.; Dolores, M.; Cruypeninck, Y.; Koning, E.; Dacher, J.N.; Savoye-Collet, C. [Rouen University Hospital-Charles Nicolle, Department of Radiology, Rouen cedex (France); Savoye, G. [Rouen University Hospital-Charles Nicolle, Department of Gastroenterology, Rouen cedex (France)

    2017-01-15

    Assessment of perianal fistulas is important to guide management of Crohn's disease (CD). Our objectives were to analyze the feasibility of magnetization transfer (MT) imaging to assess fistulas and to evaluate its contribution in assessing disease activity. During 15 months, all patients referred for perianal fistulas in CD underwent 3T-MRI including diffusion, T2/T1-weighted gadolinium-enhanced sequences and MT sequences (one with an off-resonance saturation pulse of 800 and one with 1200 Hz). We collected Van Assche score, fistula activity signs by analyzing T2, diffusion and contrast enhancement. We calculated MT ratio (MTR) with a ROI in the largest fistula. Twenty-nine patients (mean 34.9 years, range 17-53) were included. Van Assche score was 11.7, range 4-21. In 22 patients, the fistula presented with a bright T2 and diffusion signal with contrast enhancement, and was characterized as active. Mean MTR was respectively 47.2 (range 12-68) and 34.3 (range 11-57) at 800 and 1200 Hz. MTR at 800 Hz was significantly lower in non-active (34, range 12-55) than in active fistulas (51, range 24-68) (p < 0.02). MTR is feasible for the assessment of fistulas in CD and in the future could be used to help identify active and non-active fistulas. (orig.)

  3. Rare earth permanent magnet with easy magnetization

    International Nuclear Information System (INIS)

    Kim, A.S.; Camp, F.E.

    1998-01-01

    Rare earth permanent magnets have high energy products and coercivities, and thus the volume miniaturization of magnetic devices has been possible with improved magnetic performance. Although the high energy products of these rare earth permanent magnets provide substantial advantages for magnetic design and application, the strong magnetic force of the magnetized magnets makes assembly difficult. Therefore, a special device is needed to assemble the magnetized magnets. On the other hand, unmagnetized magnets are assembled and then they are magnetized. The assembled magnets are generally more difficult to magnetize than unassembled magnets because a much less effective magnetic field may be applied to them. This is particularly true for the rare earth permanent magnets because they usually need a much higher magnetic field to be fully magnetized than alnico or ferrite magnets. To obtain optimum magnetic properties, the required minimum magnetizing fields for SmCo 5 , Sm 2 TM 17 and Nd 2 Fe 14 B magnets were reported as 25-30 kOe, 45-60 kOe and 25-30 kOe, respectively. If the required magnetizing field for full saturation could be lowered, the effective utilization of magnetic properties would be maximized and the magnetic design option could be expanded with reduced restrictions. To meet this demand, we have sought to lower the field required for full magnetic saturation, and found that an increase in Dy content in R-(Fe,Co,Cu)-B type magnets lowers the field required for full saturation as well as improves the temperature stability. By increasing the H ci with Dy addition from 14 kOe to 24 and 34 kOe, the field required for full magnetic saturation decreases from about 20 to 15 and 10 kOe, respectively. This dual benefit will open up new application areas with more freedom for magnet design options. The mechanism for the lower magnetizing fields will be discussed. (orig.)

  4. Rectifier transformer saturation on commutation failure

    International Nuclear Information System (INIS)

    Lu, E.; Bronner, G.

    1989-01-01

    The rectifier transformer's service differs from the power transformer's service because of the rectifier load. Under certain fault conditions, such as a commutation failure, d.c. magnetization may be introduced into the rectifier transformer cores, resulting in possible saturation of the magnetic circuit, thus in degradation of the performance of the transformer. It is the purpose of this paper to present an approach for evaluating the electromagnetic transient process under such a fault condition. The studies were made on the operating 1000MVA converter system at the Princeton Plasma Physics Laboratory

  5. Probing peptide fragment ion structures by combining sustained off-resonance collision-induced dissociation and gas-phase H/D exchange (SORI-HDX) in Fourier transform ion-cyclotron resonance (FT-ICR) instruments.

    Science.gov (United States)

    Somogyi, Arpád

    2008-12-01

    The usefulness of gas-phase H/D exchange is demonstrated to probe heterogeneous fragment and parent ion populations. Singly and multiply protonated peptides/proteins were fragmented by using sustained off-resonance irradiation collision-induced dissociation (SORI-CID). The fragments and the surviving precursor ions then all undergo H/D exchange in the gas-phase with either D(2)O or CD(3)OD under the same experimental conditions. Usually, 10 to 60 s of reaction time is adequate to monitor characteristic differences in the H/D exchange kinetic rates. These differences are then correlated to isomeric ion structures. The SORI-HDX method can be used to rapidly test fragment ion structures and provides useful insights into peptide fragmentation mechanisms.

  6. Measurement of gradient magnetic field temporal characteristics

    International Nuclear Information System (INIS)

    Bartusek, K.; Jflek, B.

    1994-01-01

    We describe a technique of measuring the time dependence and field distortions of magnetic fields due to eddy currents (EC) produced by time-dependent magnetic field gradients. The EC measuring technique makes use of a large volume sample and selective RF excitation pulses and free induction decay (FID) (or a spin or gradient echo) to measure the out-of-phase component of the FID, which is proportional to γδB, i.e. the amount the signal is off resonance. The measuring technique is sensitive, easy to implement and interpret, and used for determining pre-emphasis compensation parameters

  7. Saturated Zone Colloid Transport

    International Nuclear Information System (INIS)

    H. S. Viswanathan

    2004-01-01

    This scientific analysis provides retardation factors for colloids transporting in the saturated zone (SZ) and the unsaturated zone (UZ). These retardation factors represent the reversible chemical and physical filtration of colloids in the SZ. The value of the colloid retardation factor, R col is dependent on several factors, such as colloid size, colloid type, and geochemical conditions (e.g., pH, Eh, and ionic strength). These factors are folded into the distributions of R col that have been developed from field and experimental data collected under varying geochemical conditions with different colloid types and sizes. Attachment rate constants, k att , and detachment rate constants, k det , of colloids to the fracture surface have been measured for the fractured volcanics, and separate R col uncertainty distributions have been developed for attachment and detachment to clastic material and mineral grains in the alluvium. Radionuclides such as plutonium and americium sorb mostly (90 to 99 percent) irreversibly to colloids (BSC 2004 [DIRS 170025], Section 6.3.3.2). The colloid retardation factors developed in this analysis are needed to simulate the transport of radionuclides that are irreversibly sorbed onto colloids; this transport is discussed in the model report ''Site-Scale Saturated Zone Transport'' (BSC 2004 [DIRS 170036]). Although it is not exclusive to any particular radionuclide release scenario, this scientific analysis especially addresses those scenarios pertaining to evidence from waste-degradation experiments, which indicate that plutonium and americium may be irreversibly attached to colloids for the time scales of interest. A section of this report will also discuss the validity of using microspheres as analogs to colloids in some of the lab and field experiments used to obtain the colloid retardation factors. In addition, a small fraction of colloids travels with the groundwater without any significant retardation. Radionuclides irreversibly

  8. MAGNET

    CERN Multimedia

    by B. Curé

    2011-01-01

    The magnet operation was very satisfactory till the technical stop at the end of the year 2010. The field was ramped down on 5th December 2010, following the successful regeneration test of the turbine filters at full field on 3rd December 2010. This will limit in the future the quantity of magnet cycles, as it is no longer necessary to ramp down the magnet for this type of intervention. This is made possible by the use of the spare liquid Helium volume to cool the magnet while turbines 1 and 2 are stopped, leaving only the third turbine in operation. This obviously requires full availability of the operators to supervise the operation, as it is not automated. The cryogenics was stopped on 6th December 2010 and the magnet was left without cooling until 18th January 2011, when the cryoplant operation resumed. The magnet temperature reached 93 K. The maintenance of the vacuum pumping was done immediately after the magnet stop, when the magnet was still at very low temperature. Only the vacuum pumping of the ma...

  9. Saturated Zone Colloid Transport

    Energy Technology Data Exchange (ETDEWEB)

    H. S. Viswanathan

    2004-10-07

    This scientific analysis provides retardation factors for colloids transporting in the saturated zone (SZ) and the unsaturated zone (UZ). These retardation factors represent the reversible chemical and physical filtration of colloids in the SZ. The value of the colloid retardation factor, R{sub col} is dependent on several factors, such as colloid size, colloid type, and geochemical conditions (e.g., pH, Eh, and ionic strength). These factors are folded into the distributions of R{sub col} that have been developed from field and experimental data collected under varying geochemical conditions with different colloid types and sizes. Attachment rate constants, k{sub att}, and detachment rate constants, k{sub det}, of colloids to the fracture surface have been measured for the fractured volcanics, and separate R{sub col} uncertainty distributions have been developed for attachment and detachment to clastic material and mineral grains in the alluvium. Radionuclides such as plutonium and americium sorb mostly (90 to 99 percent) irreversibly to colloids (BSC 2004 [DIRS 170025], Section 6.3.3.2). The colloid retardation factors developed in this analysis are needed to simulate the transport of radionuclides that are irreversibly sorbed onto colloids; this transport is discussed in the model report ''Site-Scale Saturated Zone Transport'' (BSC 2004 [DIRS 170036]). Although it is not exclusive to any particular radionuclide release scenario, this scientific analysis especially addresses those scenarios pertaining to evidence from waste-degradation experiments, which indicate that plutonium and americium may be irreversibly attached to colloids for the time scales of interest. A section of this report will also discuss the validity of using microspheres as analogs to colloids in some of the lab and field experiments used to obtain the colloid retardation factors. In addition, a small fraction of colloids travels with the groundwater without any significant

  10. Saturated tearing modes in tokamaks. Renewal proposal, progress report

    International Nuclear Information System (INIS)

    Bateman, G.

    1984-01-01

    We have completed a computer code (GTOR) implementing our quasilinear method for determining saturated tearing mode magnetic island widths in axisymmetric toroidal plasmas. With this code we have surveyed the effect of current profile, aspect ratio and plasma elongation on saturated tearing modes. Current peaking within the islands is found to have a particularly large effect. In support of this research, we have developed a direct method for computing Hamada coordinates from harmonics of the inverse Grad-Shafranov equation

  11. Nonlinear saturation of dissipative trapped ion instability and anomalous transport

    International Nuclear Information System (INIS)

    Sugihara, Masayoshi; Ogasawara, Masatada.

    1977-04-01

    An expression for the turbulent collision frequency is derived by summing up the most dominant terms from each order in the perturbation expansion in order to obtain the nonlinear saturation level of the dissipative trapped ion instability. Numerical calculation shows that the anomalous diffusion coefficient at the saturated state is in good agreement with the result of Kadomtsev and Pogutse when the effect of the magnetic shear is taken into account. (auth.)

  12. Tearing mode saturation with finite pressure

    International Nuclear Information System (INIS)

    Lee, J.K.

    1988-01-01

    With finite pressure, the saturation of the current-driven tearing mode is obtained in three-dimensional nonlinear resistive magnetohydrodynamic simulations for Tokamak plasmas. To effectively focus on the tearing modes, the perturbed pressure effects are excluded while the finite equilibrium pressure effects are retained. With this model, the linear growth rates of the tearing modes are found to be very insensitive to the equilibrium pressure increase. The nonlinear aspects of the tearing modes, however, are found to be very sensitive to the pressure increase in that the saturation level of the nonlinear harmonics of the tearing modes increases monotonically with the pressure rise. The increased level is associated with enhanced tearing island sizes or increased stochastic magnetic field region. (author)

  13. nitrogen saturation in stream ecosystems

    OpenAIRE

    Earl, S. R.; Valett, H. M.; Webster, J. R.

    2006-01-01

    The concept of nitrogen (N) saturation has organized the assessment of N loading in terrestrial ecosystems. Here we extend the concept to lotic ecosystems by coupling Michaelis-Menten kinetics and nutrient spiraling. We propose a series of saturation response types, which may be used to characterize the proximity of streams to N saturation. We conducted a series of short-term N releases using a tracer ((NO3)-N-15-N) to measure uptake. Experiments were conducted in streams spanning a gradient ...

  14. Saturation Detection-Based Blocking Scheme for Transformer Differential Protection

    Directory of Open Access Journals (Sweden)

    Byung Eun Lee

    2014-07-01

    Full Text Available This paper describes a current differential relay for transformer protection that operates in conjunction with a core saturation detection-based blocking algorithm. The differential current for the magnetic inrush or over-excitation has a point of inflection at the start and end of each saturation period of the transformer core. At these instants, discontinuities arise in the first-difference function of the differential current. The second- and third-difference functions convert the points of inflection into pulses, the magnitudes of which are large enough to detect core saturation. The blocking signal is activated if the third-difference of the differential current is larger than the threshold and is maintained for one cycle. In addition, a method to discriminate between transformer saturation and current transformer (CT saturation is included. The performance of the proposed blocking scheme was compared with that of a conventional harmonic blocking method. The test results indicate that the proposed scheme successfully discriminates internal faults even with CT saturation from the magnetic inrush, over-excitation, and external faults with CT saturation, and can significantly reduce the operating time delay of the relay.

  15. Thermal effects on tearing mode saturation

    International Nuclear Information System (INIS)

    Kim, J.S.; Chu, M.S.; Greene, J.M.

    1988-01-01

    The effect of geometry on tearing modes, saturated states of tearing modes, and the thermal effect on tearing modes are presented. The configuration of current and magnetic fields are quite different in slabs and in Tokamaks. However, for any magnetic island regardless of geometry and heating conditions, at island saturation the product of resistivity and current is the same at magnetic O and X lines. The temperature perturbation effect on the nonlinear development of tearing modes is investigated. Thermal conduction along the field lines is much faster than that in the perpendicular direction, and thus the temperature profile follows the island structure. Utilizing Spitzer's conductivity relation, the temperature perturbation is modelled as helical components of resistivity. For a usual tearing mode unstable Tokamak, where shear is positive, the islands continue to grow to a larger size when the islands are cooled. When they are heated, the island sizes are reduced. The temperature perturbation can induce islands even for equilibria stable with respect to tearing modes. Again, the islands appear when cooling takes place. The equilibria with the cooled islands show enhanced field line stochasticity, thus enhanced heat transport. Therefore, thermal instability can be directly related to pressure disruptions. (author)

  16. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    Operation of the magnet has gone quite smoothly during the first half of this year. The magnet has been at 4.5K for the full period since January. There was an unplanned short stop due to the CERN-wide power outage on May 28th, which caused a slow dump of the magnet. Since this occurred just before a planned technical stop of the LHC, during which access in the experimental cavern was authorized, it was decided to leave the magnet OFF until 2nd June, when magnet was ramped up again to 3.8T. The magnet system experienced a fault also resulting in a slow dump on April 14th. This was triggered by a thermostat on a filter choke in the 20kA DC power converter. The threshold of this thermostat is 65°C. However, no variation in the water-cooling flow rate or temperature was observed. Vibration may have been the root cause of the fault. All the thermostats have been checked, together with the cables, connectors and the read out card. The tightening of the inductance fixations has also been checked. More tem...

  17. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      The magnet was energised at the beginning of March 2012 at a low current to check all the MSS safety chains. Then the magnet was ramped up to 3.8 T on 6 March 2012. Unfortunately two days later an unintentional switch OFF of the power converter caused a slow dump. This was due to a misunderstanding of the CCC (CERN Control Centre) concerning the procedure to apply for the CMS converter control according to the beam-mode status at that time. Following this event, the third one since 2009, a discussion was initiated to define possible improvement, not only on software and procedures in the CCC, but also to evaluate the possibility to upgrade the CMS hardware to prevent such discharge from occurring because of incorrect procedure implementations. The magnet operation itself was smooth, and no power cuts took place. As a result, the number of magnetic cycles was reduced to the minimum, with only two full magnetic cycles from 0 T to 3.8 T. Nevertheless the magnet suffered four stops of the cryogeni...

  18. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      Following the unexpected magnet stops last August due to sequences of unfortunate events on the services and cryogenics [see CMS internal report], a few more events and initiatives again disrupted the magnet operation. All the magnet parameters stayed at their nominal values during this period without any fault or alarm on the magnet control and safety systems. The magnet was stopped for the September technical stop to allow interventions in the experimental cavern on the detector services. On 1 October, to prepare the transfer of the liquid nitrogen tank on its new location, several control cables had to be removed. One cable was cut mistakenly, causing a digital input card to switch off, resulting in a cold-box (CB) stop. This tank is used for the pre-cooling of the magnet from room temperature down to 80 K, and for this reason it is controlled through the cryogenics control system. Since the connection of the CB was only allowed for a field below 2 T to avoid the risk of triggering a fast d...

  19. Wood construction and magnetic characteristics of impregnated type magnetic wood

    International Nuclear Information System (INIS)

    Oka, Hideo; Hojo, Atsushi; Seki, Kyoushiro; Takashiba, Toshio

    2002-01-01

    The results of experiments involving the AC and DC magnetic characteristics of impregnated type magnetic wood were studied by taking into consideration the wood construction and fiber direction. The experimental results show that the sufficient amount of impregnated magnetic fluid varies depending on the fiber direction and length, and the grain face of the wood material. The impregnated type magnetic wood sample that is fully impregnated by magnetic fluid has a 60% saturation magnetization compared to the saturation magnetization of magnetic fluid. Samples for which the wood fiber direction was the same as the direction of the magnetic path had a higher magnetization intensity and permeability

  20. Saturation and linear transport equation

    International Nuclear Information System (INIS)

    Kutak, K.

    2009-03-01

    We show that the GBW saturation model provides an exact solution to the one dimensional linear transport equation. We also show that it is motivated by the BK equation considered in the saturated regime when the diffusion and the splitting term in the diffusive approximation are balanced by the nonlinear term. (orig.)

  1. Misconceptions in Reporting Oxygen Saturation

    NARCIS (Netherlands)

    Toffaletti, John; Zijlstra, Willem G.

    2007-01-01

    BACKGROUND: We describe some misconceptions that have become common practice in reporting blood gas and cooximetry results. In 1980, oxygen saturation was incorrectly redefined in a report of a new instrument for analysis of hemoglobin (Hb) derivatives. Oxygen saturation (sO(2)) was redefined as the

  2. MAGNET

    CERN Multimedia

    B. Curé

    2012-01-01

      The magnet and its sub-systems were stopped at the beginning of the winter shutdown on 8th December 2011. The magnet was left without cooling during the cryogenics maintenance until 17th January 2012, when the cryoplant operation resumed. The magnet temperature reached 93 K. The vacuum pumping was maintained during this period. During this shutdown, the yearly maintenance was performed on the cryogenics, the vacuum pumps, the magnet control and safety systems, and the power converter and discharge lines. Several preventive actions led to the replacement of the electrovalve command coils, and the 20A DC power supplies of the magnet control system. The filters were cleaned on the demineralised water circuits. The oil of the diffusion pumps was changed. On the cryogenics, warm nitrogen at 343 K was circulated in the cold box to regenerate the filters and the heat exchangers. The coalescing filters have been replaced at the inlet of both the turbines and the lubricant trapping unit. The active cha...

  3. MAGNET

    CERN Multimedia

    B. Curé

    2013-01-01

      The magnet was operated without any problem until the end of the LHC run in February 2013, apart from a CERN-wide power glitch on 10 January 2013 that affected the CMS refrigerator, causing a ramp down to 2 T in order to reconnect the coldbox. Another CERN-wide power glitch on 15 January 2013 didn’t affect the magnet subsystems, the cryoplant or the power converter. At the end of the magnet run, the reconnection of the coldbox at 2.5 T was tested. The process will be updated, in particular the parameters of some PID valve controllers. The helium flow of the current leads was reduced but only for a few seconds. The exercise will be repeated with the revised parameters to validate the automatic reconnection process of the coldbox. During LS1, the water-cooling services will be reduced and many interventions are planned on the electrical services. Therefore, the magnet cryogenics and subsystems will be stopped for several months, and the magnet cannot be kept cold. In order to avoid unc...

  4. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    The magnet was successfully operated at the end of the year 2009 despite some technical problems on the cryogenics. The magnet was ramped up to 3.8 T at the end of November until December 16th when the shutdown started. The magnet operation met a few unexpected stops. The field was reduced to 3.5 T for about 5 hours on December 3rd due to a faulty pressure sensor on the helium compressor. The following day the CERN CCC stopped unintentionally the power converters of the LHC and the experiments, triggering a ramp down that was stopped at 2.7 T. The magnet was back at 3.8 T about 6 hours after CCC sent the CERN-wide command. Three days later, a slow dump was triggered due to a stop of the pump feeding the power converter water-cooling circuit, during an intervention on the water-cooling plant done after several disturbances on the electrical distribution network. The magnet was back at 3.8 T in the evening the same day. On December 10th a break occurred in one turbine of the cold box producing the liquid ...

  5. MAGNET

    CERN Multimedia

    B. Curé

    2011-01-01

    The CMS magnet has been running steadily and smoothly since the summer, with no detected flaw. The magnet instrumentation is entirely operational and all the parameters are at their nominal values. Three power cuts on the electrical network affected the magnet run in the past five months, with no impact on the data-taking as the accelerator was also affected at the same time. On 22nd June, a thunderstorm caused a power glitch on the service electrical network. The primary water cooling at Point 5 was stopped. Despite a quick restart of the water cooling, the inlet temperature of the demineralised water on the busbar cooling circuit increased by 5 °C, up to 23.3 °C. It was kept below the threshold of 27 °C by switching off other cooling circuits to avoid the trigger of a slow dump of the magnet. The cold box of the cryogenics also stopped. Part of the spare liquid helium volume was used to maintain the cooling of the magnet at 4.5 K. The operators of the cryogenics quickly restarted ...

  6. Photoinduced quantum spin and valley Hall effects, and orbital magnetization in monolayer MoS2

    KAUST Repository

    Tahir, M.

    2014-09-22

    We theoretically demonstrate that 100% valley-polarized transport in monolayers of MoS2 and other group-VI dichalcogenides can be obtained using off-resonant circularly polarized light. By tuning the intensity of the off-resonant light the intrinsic band gap in one valley is reduced, while it is enhanced in the other valley, enabling single valley quantum transport. As a consequence, we predict (i) enhancement of the longitudinal electrical conductivity, accompanied by an increase in the spin polarization of the flowing electrons, (ii) enhancement of the intrinsic spin Hall effect, together with a reduction of the intrinsic valley Hall effect, and (iii) enhancement of the orbital magnetic moment and orbital magnetization. These mechanisms provide appealing opportunities to the design of nanoelectronics based on dichalcogenides.

  7. Photoinduced quantum spin and valley Hall effects, and orbital magnetization in monolayer MoS2

    KAUST Repository

    Tahir, M.; Manchon, Aurelien; Schwingenschlö gl, Udo

    2014-01-01

    We theoretically demonstrate that 100% valley-polarized transport in monolayers of MoS2 and other group-VI dichalcogenides can be obtained using off-resonant circularly polarized light. By tuning the intensity of the off-resonant light the intrinsic band gap in one valley is reduced, while it is enhanced in the other valley, enabling single valley quantum transport. As a consequence, we predict (i) enhancement of the longitudinal electrical conductivity, accompanied by an increase in the spin polarization of the flowing electrons, (ii) enhancement of the intrinsic spin Hall effect, together with a reduction of the intrinsic valley Hall effect, and (iii) enhancement of the orbital magnetic moment and orbital magnetization. These mechanisms provide appealing opportunities to the design of nanoelectronics based on dichalcogenides.

  8. MAGNET

    CERN Multimedia

    B. Curé

    2011-01-01

    The magnet ran smoothly in the last few months until a fast dump occurred on 9th May 2011. Fortunately, this occurred in the afternoon of the first day of the technical stop. The fast dump was due to a valve position controller that caused the sudden closure of a valve. This valve is used to regulate the helium flow on one of the two current leads, which electrically connects the coil at 4.5 K to the busbars at room temperature. With no helium flow on the lead, the voltage drop and the temperatures across the leads increase up to the defined thresholds, triggering a fast dump through the Magnet Safety System (MSS). The automatic reaction triggered by the MSS worked properly. The helium release was limited as the pressure rise was just at the limit of the safety valve opening pressure. The average temperature of the magnet reached 72 K. It took four days to recover the temperature and refill the helium volumes. The faulty valve controller was replaced by a spare one before the magnet ramp-up resumed....

  9. Simulation of saturated tearing modes in tokamaks

    International Nuclear Information System (INIS)

    Nguyen, Canh N.; Bateman, Glenn; Kritz, Arnold H.

    2004-01-01

    A quasi-linear model, which includes the effect of the neoclassical bootstrap current, is developed for saturated tearing modes in order to compute magnetic island widths in axisymmetric toroidal plasmas with arbitrary aspect ratio and cross-sectional shape. The model is tested in a simple stand-alone code and is implemented in the BALDUR [C. E. Singer et al., Comput. Phys. Commun. 49, 275 (1982)] predictive modeling code. It is found that the widths of tearing mode islands increase with decreasing aspect ratio and with increasing elongation. Also, the island widths increase when the gradient of the current density increases at the edge of the islands and when the current density inside the islands is suppressed, such as the suppression caused by the near absence of the bootstrap current within the islands. In simulations of tokamak discharges, it is found that tearing mode island widths oscillate in time in response to periodic sawtooth crashes. The local enhancements in the transport produced by magnetic islands have a noticeable effect on global plasma confinement in simulations of low aspect ratio, high beta tokamaks, where saturated tearing mode islands can occur with widths that are greater than 15% of the plasma minor radius

  10. Landsliding in partially saturated materials

    Science.gov (United States)

    Godt, J.W.; Baum, R.L.; Lu, N.

    2009-01-01

    [1] Rainfall-induced landslides are pervasive in hillslope environments around the world and among the most costly and deadly natural hazards. However, capturing their occurrence with scientific instrumentation in a natural setting is extremely rare. The prevailing thinking on landslide initiation, particularly for those landslides that occur under intense precipitation, is that the failure surface is saturated and has positive pore-water pressures acting on it. Most analytic methods used for landslide hazard assessment are based on the above perception and assume that the failure surface is located beneath a water table. By monitoring the pore water and soil suction response to rainfall, we observed shallow landslide occurrence under partially saturated conditions for the first time in a natural setting. We show that the partially saturated shallow landslide at this site is predictable using measured soil suction and water content and a novel unified effective stress concept for partially saturated earth materials. Copyright 2009 by the American Geophysical Union.

  11. Nitrogen saturation in stream ecosystems.

    Science.gov (United States)

    Earl, Stevan R; Valett, H Maurice; Webster, Jackson R

    2006-12-01

    The concept of nitrogen (N) saturation has organized the assessment of N loading in terrestrial ecosystems. Here we extend the concept to lotic ecosystems by coupling Michaelis-Menten kinetics and nutrient spiraling. We propose a series of saturation response types, which may be used to characterize the proximity of streams to N saturation. We conducted a series of short-term N releases using a tracer (15NO3-N) to measure uptake. Experiments were conducted in streams spanning a gradient of background N concentration. Uptake increased in four of six streams as NO3-N was incrementally elevated, indicating that these streams were not saturated. Uptake generally corresponded to Michaelis-Menten kinetics but deviated from the model in two streams where some other growth-critical factor may have been limiting. Proximity to saturation was correlated to background N concentration but was better predicted by the ratio of dissolved inorganic N (DIN) to soluble reactive phosphorus (SRP), suggesting phosphorus limitation in several high-N streams. Uptake velocity, a reflection of uptake efficiency, declined nonlinearly with increasing N amendment in all streams. At the same time, uptake velocity was highest in the low-N streams. Our conceptual model of N transport, uptake, and uptake efficiency suggests that, while streams may be active sites of N uptake on the landscape, N saturation contributes to nonlinear changes in stream N dynamics that correspond to decreased uptake efficiency.

  12. MAGNET

    CERN Multimedia

    Benoit Curé

    2010-01-01

    The magnet worked very well at 3.8 T as expected, despite a technical issue that manifested twice in the cryogenics since June. All the other magnet sub-systems worked without flaw. The issue in the cryogenics was with the cold box: it could be observed that the cold box was getting progressively blocked, due to some residual humidity and air accumulating in the first thermal exchanger and in the adsorber at 65 K. This was later confirmed by the analysis during the regeneration phases. An increase in the temperature difference between the helium inlet and outlet across the heat exchanger and a pressure drop increase on the filter of the adsorber were observed. The consequence was a reduction of the helium flow, first compensated by the automatic opening of the regulation valves. But once they were fully opened, the flow and refrigeration power reduced as a consequence. In such a situation, the liquid helium level in the helium Dewar decreased, eventually causing a ramp down of the magnet current and a field...

  13. MAGNET

    CERN Multimedia

    B. Curé

    MAGNET During the winter shutdown, the magnet subsystems went through a full maintenance. The magnet was successfully warmed up to room temperature beginning of December 2008. The vacuum was broken later on by injecting nitrogen at a pressure just above one atmosphere inside the vacuum tank. This was necessary both to prevent any accidental humidity ingress, and to allow for a modification of the vacuum gauges on the vacuum tank and maintenance of the diffusion pumps. The vacuum gauges had to be changed, because of erratic variations on the measurements, causing spurious alarms. The new type of vacuum gauges has been used in similar conditions on the other LHC experiments and without problems. They are shielded against the stray field. The lubricants of the primary and diffusion pumps have been changed. Several minor modifications were also carried out on the equipment in the service cavern, with the aim to ease the maintenance and to allow possible intervention during operation. Spare sensors have been bough...

  14. 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...

  15. 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...

  16. Off-Resonance Acoustic Levitation Without Rotation

    Science.gov (United States)

    Barmatz, M. B.; Allen, J. L.

    1984-01-01

    Orthogonal acoustic-levitation modes excited at slightly different frequencies to control rotation. Rotation of object in square cross-section acoustic-levitation chamber stopped by detuning two orthogonal (x and y) excitation drivers in plane of square cross section. Detuning done using fundamental degenerate modes or odd harmonic modes.

  17. MAGNET

    CERN Multimedia

    Benoit Curé

    The magnet subsystems resumed operation early this spring. The vacuum pumping was restarted mid March, and the cryogenic power plant was restarted on March 30th. Three and a half weeks later, the magnet was at 4.5 K. The vacuum pumping system is performing well. One of the newly installed vacuum gauges had to be replaced at the end of the cool-down phase, as the values indicated were not coherent with the other pressure measurements. The correction had to be implemented quickly to be sure no helium leak could be at the origin of this anomaly. The pressure measurements have been stable and coherent since the change. The cryogenics worked well, and the cool-down went quite smoothly, without any particular difficulty. The automated start of the turbines had to be fine-tuned to get a smooth transition, as it was observed that the cooling power delivered by the turbines was slightly higher than needed, causing the cold box to stop automatically. This had no consequence as the cold box safety system acts to keep ...

  18. MAGNET

    CERN Multimedia

    B. Curé

    During the winter shutdown, the magnet subsystems went through a full maintenance. The magnet was successfully warmed up to room temperature beginning of December 2008. The vacuum was broken later on by injecting nitrogen at a pressure just above one atmosphere inside the vacuum tank. This was necessary both to prevent any accidental humidity ingress, and to allow for a modification of the vacuum gauges on the vacuum tank and maintenance of the diffusion pumps. The vacuum gauges had to be changed, because of erratic variations on the measurements, causing spurious alarms. The new type of vacuum gauges has been used in similar conditions on the other LHC experiments and without problems. They are shielded against the stray field. The lubricants of the primary and diffusion pumps have been changed. Several minor modifications were also carried out on the equipment in the service cavern, with the aim to ease the maintenance and to allow possible intervention during operation. Spare sensors have been bought. Th...

  19. Differentiated-effect shims for medium field levels and saturation

    International Nuclear Information System (INIS)

    Richie, A.

    1976-01-01

    The arrangement of shims on the upstream and downstream ends of magnets may be based on the independent effects of variations in the geometric length and degree of saturation at the edges of the poles. This technique can be used to match the bending strength of an accelerator's magnets at two field levels (medium fields and maximum fields) and thus save special procedures (mixing the laminations, local compensation for errors by arranging the magnets in the appropriate order) and special devices (for instance, correcting dipoles) solely for correcting bending strengths at low field levels. (Auth.)

  20. Coherence length saturation at the low temperature limit in two-dimensional hole gas

    Science.gov (United States)

    Shan, Pujia; Fu, Hailong; Wang, Pengjie; Yang, Jixiang; Pfeiffer, L. N.; West, K. W.; Lin, Xi

    2018-05-01

    The plateau-plateau transition in the integer quantum Hall effect is studied in three Hall bars with different widths. The slopes of the Hall resistance as a function of magnetic field follow the scaling power law as expected in the plateau-plateau transition, and saturate at the low temperature limit. Surprisingly, the saturation temperature is irrelevant with the Hall bar size, which suggests that the saturation of the coherence length is intrinsic.

  1. Comparative analysis of magnetic resonance in the polaron pair recombination and the triplet exciton-polaron quenching models

    Science.gov (United States)

    Mkhitaryan, V. V.; Danilović, D.; Hippola, C.; Raikh, M. E.; Shinar, J.

    2018-01-01

    We present a comparative theoretical study of magnetic resonance within the polaron pair recombination (PPR) and the triplet exciton-polaron quenching (TPQ) models. Both models have been invoked to interpret the photoluminescence detected magnetic resonance (PLDMR) results in π -conjugated materials and devices. We show that resonance line shapes calculated within the two models differ dramatically in several regards. First, in the PPR model, the line shape exhibits unusual behavior upon increasing the microwave power: it evolves from fully positive at weak power to fully negative at strong power. In contrast, in the TPQ model, the PLDMR is completely positive, showing a monotonic saturation. Second, the two models predict different dependencies of the resonance signal on the photoexcitation power, PL. At low PL, the resonance amplitude Δ I /I is ∝PL within the PPR model, while it is ∝PL2 crossing over to PL3 within the TPQ model. On the physical level, the differences stem from different underlying spin dynamics. Most prominently, a negative resonance within the PPR model has its origin in the microwave-induced spin-Dicke effect, leading to the resonant quenching of photoluminescence. The spin-Dicke effect results from the spin-selective recombination, leading to a highly correlated precession of the on-resonance pair partners under the strong microwave power. This effect is not relevant for TPQ mechanism, where the strong zero-field splitting renders the majority of triplets off resonance. On the technical level, the analytical evaluation of the line shapes for the two models is enabled by the fact that these shapes can be expressed via the eigenvalues of a complex Hamiltonian. This bypasses the necessity of solving the much larger complex linear system of the stochastic Liouville equations. Our findings pave the way towards a reliable discrimination between the two mechanisms via cw PLDMR.

  2. Magnetization transfer on T2-weighted image : magnetization Transfer ratios in normal brain and cerebral lesions

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Myung Kwan; Roh, Hong Gee; Suh, Chang Hae; Cho, Young Kook; Kim, Hyung Jin; Kim, Jin Hee; Kim, Sung Tae; Choi, Sung Kyu [Inha Univ. College of Medicine, Incheon (Korea, Republic of)

    1998-07-01

    To evaluate the magnetization transfer ratio(MTR) of various normal structures and pathologic lesions, as seen on magnetization transfer T2-weighted images (MT+T2WI). Materials and Methods : In ten normal volunteers, T2-weighted images without MT (MT-T2WI) and with MT(MT+T2WI) were obtained. Off-set pulses used in MT+T2WI were 400, 600, 1000, 1500, and 2000Hz. In 60 clinical cases infarction(n=10), brain tumors(n=5), traumatic hematomas(n=5), other hematomas(n=3) vascular malformation(n=2) white matter disease(n=2) normal(n=31) and others(n=2), both MT-T2WI and MT+T2WI images were obtained using an off-set pulse of 600 Hz. In all volunteers and patients, MTR in various normal brain parenchyma and abnormal areas was measured. Results : The MTRs of white and gray matter were 48% and 45% respectively at 400 Hz, 26% and 22% at 600Hz, 12% and 11% of 1000Hz, 10% and 9% 1500HZ, and 9% and 8% at 2000Hz of RF. The MTR of CSF was 43% at 400 Hz of off-resonance RF, while the contrast resolution of T2WI was poor. An off-resonance of 600Hz appeared to be the optimal frequency. In diseased areas,MTRs varied but were usually similar to or lower than those of brain parenchyma. Conclusion : The optimal off-resonance RF on MT+T2WI appears to be 600 Hz for relatively high MTR of brain parenchyma and low MTR of CSF,in which MTRs of white and gray matter were 26% and 22%, respectively, of 600Hz off-set pulse. The MTRs of cerebral lesions varied and further studies of various cerebral lesions are needed.

  3. Magnetic

    Science.gov (United States)

    Aboud, Essam; El-Masry, Nabil; Qaddah, Atef; Alqahtani, Faisal; Moufti, Mohammed R. H.

    2015-06-01

    The Rahat volcanic field represents one of the widely distributed Cenozoic volcanic fields across the western regions of the Arabian Peninsula. Its human significance stems from the fact that its northern fringes, where the historical eruption of 1256 A.D. took place, are very close to the holy city of Al-Madinah Al-Monawarah. In the present work, we analyzed aeromagnetic data from the northern part of Rahat volcanic field as well as carried out a ground gravity survey. A joint interpretation and inversion of gravity and magnetic data were used to estimate the thickness of the lava flows, delineate the subsurface structures of the study area, and estimate the depth to basement using various geophysical methods, such as Tilt Derivative, Euler Deconvolution and 2D modeling inversion. Results indicated that the thickness of the lava flows in the study area ranges between 100 m (above Sea Level) at the eastern and western boundaries of Rahat Volcanic field and getting deeper at the middle as 300-500 m. It also showed that, major structural trend is in the NW direction (Red Sea trend) with some minor trends in EW direction.

  4. MAGNET

    CERN Multimedia

    Benoit Curé

    The cooling down to the nominal temperature of 4.5 K was achieved at the beginning of August, in conjunction with the completion of the installation work of the connection between the power lines and the coil current leads. The temperature gradient on the first exchanger of the cold box is now kept within the nominal range. A leak of lubricant on a gasket of the helium compressor station installed at the surface was observed and several corrective actions were necessary to bring the situation back to normal. The compressor had to be refilled with lubricant and a regeneration of the filters and adsorbers was necessary. The coil cool down was resumed successfully, and the cryogenics is running since then with all parameters being nominal. Preliminary tests of the 20kA coil power supply were done earlier at full current through the discharge lines into the dump resistors, and with the powering busbars from USC5 to UXC5 without the magnet connected. On Monday evening August 25th, at 8pm, the final commissionin...

  5. MAGNET

    CERN Document Server

    B. Curé

    The first phase of the commissioning ended in August by a triggered fast dump at 3T. All parameters were nominal, and the temperature recovery down to 4.5K was carried out in two days by the cryogenics. In September, series of ramps were achieved up to 3 and finally 3.8T, while checking thoroughly the detectors in the forward region, measuring any movement of and around the HF. After the incident of the LHC accelerator on September 19th, corrective actions could be undertaken in the forward region. When all these displacements were fully characterized and repetitive, with no sign of increments in displacement at each field ramp, it was possible to start the CRAFT, Cosmic Run at Four Tesla (which was in fact at 3.8T). The magnet was ramped up to 18.16kA and the 3 week run went smoothly, with only 4 interruptions: due to the VIP visits on 21st October during the LHC inauguration day; a water leak on the cooling demineralized water circuit, about 1 l/min, that triggered a stop of the cooling pumps, and resulte...

  6. MAGNET

    CERN Multimedia

    Benoit Curé

    2013-01-01

    Maintenance work and consolidation activities on the magnet cryogenics and its power distribution are progressing according to the schedules. The manufacturing of the two new helium compressor frame units has started. The frame units support the valves, all the sensors and the compressors with their motors. This activity is subcontracted. The final installation and the commissioning at CERN are scheduled for March–April 2014. The overhauls of existing cryogenics equipment (compressors, motors) are in progress. The reassembly of the components shall start in early 2014. The helium drier, to be installed on the high-pressure helium piping, has been ordered and will be delivered in the first trimester of 2014. The power distribution for the helium compressors in SH5 on the 3.3kV network is progressing. The 3.3kV switches, between each compressor and its hot spare compressor, are being installed, together with the power cables for the new compressors. The 3.3kV electrical switchboards in SE5 will ...

  7. Impulse Magnetization of Nd-Fe-B Sintered Magnets for Sensors

    Directory of Open Access Journals (Sweden)

    Marek Przybylski

    2016-04-01

    Full Text Available Magnetization of large Nd-Fe-B sintered permanent magnets is still challenging. This type of permanent magnet is electrically conductive, so impulse magnetization causes a flow of eddy currents which prevent magnetization of the whole volume of the magnet. The paper deals with the impulse magnetization of sintered Nd-Fe-B permanent magnets and shows a method for the determination of suitable parameters for the supply system. The necessary magnetic field strength for magnetization of the magnet to saturation was determined. The optimal magnetizing fixture supply voltage for magnetization to saturation was determined from simulations in PSpice software, finite element analyses in Maxwell 15 and measurements. Measurements of magnetic induction on the surface of the Nd-Fe-B magnet are also presented to ensure that a magnet with 70 mm diameter and 20 mm in height is fully saturated.

  8. Improved dq-Axes Model of PMSM Considering Airgap Flux Harmonics and Saturation

    DEFF Research Database (Denmark)

    Fasil, Muhammed; Antaloae, Ciprian; Mijatovic, Nenad

    2016-01-01

    In this work, the classical linear model of a permanent magnet synchronous motor (PMSM) is modified by adding d and q-axes harmonic inductances so that the modified model can consider non-linearities present in an interior permanent magnet (IPM) motor. Further, a method has been presented to assess...... the effect of saturation and cross-saturation on constant torque curves of PMSM. Two IPM motors with two different rotor topologies and different specifications are designed to evaluate the effect of saturation on synchronous and harmonic inductances, and on operating points of the machines...

  9. Electron-cyclotron maser utilizing free-electron two-quantum magnetic-wiggler radiation, and explanation of effective laser injection in an electron cyclotron maser as lift-up of saturated power level arisen from uncertainty in electron energy due to electron's transverse wiggling

    Science.gov (United States)

    Kim, S. H.

    2017-12-01

    We reason that in the free-electron radiation if the transition rate τ is less than the radiation frequency ν, the radiation is of broad-band spectrum whereas if τ ≫ ν, the radiation is of monochromatic. We find that when a weaker magnetic wiggler (MW) is superpositioned on a predominantly strong uniform magnetic field, free-electron two-quantum magnetic-wiggler (FETQMW) radiation takes place. In FETQMW radiation, the MW and the electron's intrinsic motivity to change its internal configuration through radiation play as two first-order perturbers while the uniform magnetic field acts as the sole zeroth-order perturber. When Δ E≪ hν, where Δ E is the uncertainty in the electron energy produced by transverse wiggling due to the MW in conjuction with a Heisenberg's uncertainty principle Δ EΔ x h and E = ( m 2 c 4 + c 2 p 2)1/2, the power of FETQMW radiation cannot exceed hν 2. However, we find that this power cap is lifted by the amount of νΔ E when Δ E ≫ hν holds [1,2]. This lift-up of the saturated radiation power is the responsible mechanism for the effective external injection of a 20 kW maser in an electron-cyclotron maser (ECM). We find that an MW-added ECM with radius 5 cm and length 1 m and operating parameters of the present beam technology can yield laser power of 50 MW at the radiation wavelength of 0.001 cm.

  10. Improved dq-axes Model of PMSM Considering Airgap Flux Harmonics and Saturation

    DEFF Research Database (Denmark)

    Fasil, Muhammed; Antaloae, Ciprian; Mijatovic, Nenad

    -saturation on constant torque curves of PMSM. Two interior permanent magnet motor with two different rotor topologies and different specifications are designed to evaluate the effect of saturation on synchronous and harmonic inductances, and operating points of the machines.......The classical dq-axes model of permanent magnet synchronous machines (PMSM) uses linear approximation. This was not an issue in earlier versions of PMSM drives because they mostly used surface magnet motors. With the arrival of interior permanent magnet (IPM) machines, which use reluctance torque...... along with magnet torque, the accuracy of linear models are found to be insufficient. In this work, the effect of air gap flux harmonics is included in the classical model of PMSM using d and q-axes harmonic inductances. Further, a method has been presented to assess the effect of saturation and cross...

  11. Laced permanent magnet quadrupole drift tube magnets

    International Nuclear Information System (INIS)

    Feinberg, B.; Behrsing, G.U.; Halbach, K.; Marks, J.S.; Morrison, M.E.; Nelson, D.H.

    1988-10-01

    A laced permanent magnet quadrupole drift tube magnet has been constructed for a proof-of-principle test. The magnet is a conventional tape-wound quadrupole electromagnet, using iron pole- pieces, with the addition of permanent magnet material (neodymium iron) between the poles to reduce the effects of saturation. The iron is preloaded with magnetic flux generated by the permanent magnet material, resulting in an asymmetrical saturation curve. Since the polarity of the quadrupole magnets in a drift tube linac is not reversed we can take advantage of this asymmetrical saturation to provide greater focusing strength. The magnet configuration has been optimized and the vanadium permendur poles needed in a conventional quadrupole have been replaced with iron poles. The use of permanent magnet material has allowed us to increase the focusing strength of the magnet by about 20% over that of a conventional tape-wound quadrupole. Comparisons will be made between this magnet and the conventional tape-wound quadrupole. 3 refs., 5 figs

  12. Magnetizing of permanent magnet using HTS bulk magnet

    International Nuclear Information System (INIS)

    Oka, Tetsuo; Muraya, Tomoki; Kawasaki, Nobutaka; Fukui, Satoshi; Ogawa, Jun; Sato, Takao; Terasawa, Toshihisa

    2011-01-01

    A demagnetized Nd-Fe-B permanent magnet was scanned just above the magnetic pole containing the HTS bulk magnet, generating a magnetic field of 3.27 T. The magnet sample was subsequently found to be fully magnetized in the open space of the static magnetic fields. We examined the magnetic field distributions when the magnetic poles were scanned twice to activate the magnetic plates inversely with various overlap distances between the tracks of the HTS bulk magnet. The magnetic field of the 'rewritten' magnet reached the values of the magnetically saturated region of the material, showing steep gradients at the border of each magnetic pole. As a replacement for conventional pulse field magnetizing methods, this technique is proposed to expand the degree of freedom in the design of electromagnetic devices, and is proposed as a novel practical method for magnetizing rare-earth magnets, which have excellent magnetic performance and require intense fields of more than 3 T to be activated. (author)

  13. Observability of linear systems with saturated outputs

    NARCIS (Netherlands)

    Koplon, R.; Sontag, E.D.; Hautus, M.L.J.

    1994-01-01

    We present necessary and sufficient conditions for observability of the class of output-saturated systems. These are linear systems whose output passes through a saturation function before it can be measured.

  14. Fault tolerant control of systems with saturations

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik

    2013-01-01

    This paper presents framework for fault tolerant controllers (FTC) that includes input saturation. The controller architecture known from FTC is based on the Youla-Jabr-Bongiorno-Kucera (YJBK) parameterization is extended to handle input saturation. Applying this controller architecture in connec......This paper presents framework for fault tolerant controllers (FTC) that includes input saturation. The controller architecture known from FTC is based on the Youla-Jabr-Bongiorno-Kucera (YJBK) parameterization is extended to handle input saturation. Applying this controller architecture...... in connection with faulty systems including input saturation gives an additional YJBK transfer function related to the input saturation. In the fault free case, this additional YJBK transfer function can be applied directly for optimizing the feedback loop around the input saturation. In the faulty case......, the design problem is a mixed design problem involved both parametric faults and input saturation....

  15. Magnetization transfer contrast MR imaging of the knee at 0.3 T

    International Nuclear Information System (INIS)

    Yoshioka, Hiroshi; Onaya, Hiroaki; Niitsu, Mamoru; Anno, Izumi; Itai, Yuji; Nishimura, Hiroshi; Kajiyama, Koji; Masuda, Tomonori; Nakajima, Kotaro.

    1994-01-01

    It has been reported that magnetization transfer contrast (MTC) images were effective in evaluating the articular cartilage. However, only one in vivo study of the articular cartilage in the knee has been demonstrated at 1.5T. The purpose of this study was to evaluate the optimal off-resonance MTC pulse at 0.3T MR imager and assess its clinical usefulness. Five normal volunteers and eleven patients with suspected knee injuries were investigated using off-resonance sinc, gaussian, constant shaped irradiation pulses. All MTC images revealed higher contrast and contrast-to-noise (C/N) ratio between articular cartilage and external reference (saline) in the normal volunteers' knee than conventional gradient recalled echo images. MTC images with the gaussian or sinc shaped pulse were judged superior to those with constant wave pulse because the former images showed a fewer artifact with lower specific absorption rate than the latter images. The sinc MTC images were performed with the lowest SAR. The gaussian MTC images revealed better contrast and C/N between articular cartilage and joint fluid than the sinc MTC images in patients. 3D MTC images using Guassian pulse were also performed within a clinically tolerable imaging time (13 min 39 sec). Thus, MTC images in the knee at 0.3T using off-resonance pulse may be effective to assess knee injury due to better contrast between articular cartilage and joint fluid. (author)

  16. Receptor saturation in roentgen films

    Energy Technology Data Exchange (ETDEWEB)

    Strid, K G; Reichmann, S [Sahlgrenska Sjukhuset, Goeteborg (Sweden)

    1980-01-01

    Roentgen-film recording of small object details of low attenuation differences (e.g. pulmonary vessels) is regularly seen to be impaired when the film is exposed to yield high values of optical density (D). This high-density failure is due to receptor saturation, which implies that at high exposure values most silver halide grains of the film are made developable, leaving few grains available to receive additional informative photons. The receptor saturation is analysed by means of a mathematical model of a non-screen film yielding Dsub(max) = 2.0. Optimum recording, defined by maximum signal-to-noise ratio in the image, is found at D approximately 0.64, corresponding to, on an average, 1.6 photons absorbed per grain. On the other hand, maximum contrast occurs at D approximately 1.4, where, on the average, 3.6 photons are absorbed per grain. The detective quantum efficiency of the film, i.e. the fraction of the photons actually contributing to the information content of the image, drops from 41 per cent at maximum signal-to-noise ratio to a mere 10 per cent at maximum contrast.

  17. Dependence of the cross polar cap potential saturation on the type of solar wind streams

    OpenAIRE

    Nikolaeva, N. S.; Yermolaev, Yu. I.; Lodkina, I. G.

    2013-01-01

    We compare of the cross polar cap potential (CPCP) saturation during magnetic storms induced by various types of the solar wind drivers. By using the model of Siscoe-Hill \\citep{Hilletal1976,Siscoeetal2002a,Siscoeetal2002b,Siscoeetal2004,Siscoe2011} we evaluate criteria of the CPCP saturation during the main phases of 257 magnetic storms ($Dst_{min} \\le -50$ nT) induced by the following types of the solar wind streams: magnetic clouds (MC), Ejecta, the compress region Sheath before MC ($Sh_{M...

  18. Semiconductor saturable absorbers for ultrafast terahertz signals

    DEFF Research Database (Denmark)

    Hoffmann, Matthias C.; Turchinovich, Dmitry

    2010-01-01

    states, due to conduction band onparabolicity and scattering into satellite valleys in strong THz fields. Saturable absorber parameters, such as linear and nonsaturable transmission, and saturation fluence, are extracted by fits to a classic saturable absorber model. Further, we observe THz pulse......We demonstrate saturable absorber behavior of n-type semiconductors GaAs, GaP, and Ge in the terahertz THz frequency range at room temperature using nonlinear THz spectroscopy. The saturation mechanism is based on a decrease in electron conductivity of semiconductors at high electron momentum...

  19. Mechanics of non-saturated soils

    International Nuclear Information System (INIS)

    Coussy, O.; Fleureau, J.M.

    2002-01-01

    This book presents the different ways to approach the mechanics of non saturated soils, from the physico-chemical aspect to the mechanical aspect, from the experiment to the theoretical modeling, from the laboratory to the workmanship, and from the microscopic scale to the macroscopic one. Content: water and its representation; experimental bases of the behaviour of non-saturated soils; transfer laws in non-saturated environment; energy approach of the behaviour of non-saturated soils; homogenization for the non-saturated soils; plasticity and hysteresis; dams and backfilling; elaborated barriers. (J.S.)

  20. Saturation in dual radiation action

    International Nuclear Information System (INIS)

    Rossi, H.H.; Zaider, M.

    1988-01-01

    The theory of dual radiation action (TDRA) was developed with the aim of applying microdosimetry to radiobiology. It therefore can deal only with the first phases in a long chain of events that results in patent effects. It is, however, clear that the initial spatial and temporal pattern of energy deposition has a profound influence on the ultimate outcome. As often happens, the early formulation of the theory contained a number of simplifying assumptions. Although most of these were explicitly stated when the first version of the TDRA was published experimental data obtained when the limitations are important were cited as contrary evidence causing considerable confusion. A more advanced version eliminated some of the restrictions but there remain others, one of which relates to certain aspects of saturation which are addressed here

  1. Application of MRIL-WD (Magnetic Resonance Imaging Logging While Drilling) for irreducible water saturation, total reservoir, free-fluid, bound-fluid porosity measurements and its value for the petrophysical analysis of RT/RM data from the Shah Deniz well

    Science.gov (United States)

    Amirov, Elnur

    2016-04-01

    , preferably while the drilling of the brand new wells (logging-while-drilling, LWD). The MRIL-WD Tool can accomplish any tasks reliably and in a timely manner thus saving drilling time and reducing the overall risk for the well. Control of water production and identification of pay zones with high irreducible water saturation are also very important for formation evaluation and petrophysical analysis in oil fields located in the Azerbaijan Republic and also other fields around the world. Sometimes above-mentioned problems can cause delay in completion decisions which will create additional expenses for field management. In many wells, breakthroughs in reservoir characterization have been achieved in directly determining hydrocarbon volumes, net permeability thickness, and hydrocarbon type, thus circumventing the problems associated with obtaining wireline data and the considerable amount of rig time required (so MRIL-WD can considerably reduce the NPT). Some reservoir zones with relatively low water saturation, which calculated from the other conventional logs, can produce with relatively high percentage of water cut, primarily because much of the water is movable. However, other zones with high calculated water saturation produce water free hydrocarbons. The difficulty in predicting water production can be related with the producing from the complex lithology, which can contain low-permeability, medium- to fine-grained shaly sands. Where grains are small, the formations have high surface to volume ratios that result in high irreducible water saturation and due to this we can see low resistivity values. As a result the use of resistivity logs as pay indicator, sometimes can cause low resistivity pay zones might be overlooked and consequently net field pay could be underestimated. In the last few years, nuclear magnetic resonance logs have shown great promise in solving problems of formation evaluation that could not be directly resolved with conventional logs. The capability

  2. ISR magnet model

    CERN Multimedia

    CERN PhotoLab

    1965-01-01

    Field measurements being made on the ISR magnet model. In the foreground, the poleface windings can be seen - as distinct from the large exciting coils - together with their supply cables. These windings are mainly used to compensate the saturation effects at high fields. The steel plates forming the yoke are welded together along the whole length of the magnet.

  3. Patterning via optical saturable transitions

    Science.gov (United States)

    Cantu, Precious

    For the past 40 years, optical lithography has been the patterning workhorse for the semiconductor industry. However, as integrated circuits have become more and more complex, and as device geometries shrink, more innovative methods are required to meet these needs. In the far-field, the smallest feature that can be generated with light is limited to approximately half the wavelength. This, so called far-field diffraction limit or the Abbe limit (after Prof. Ernst Abbe who first recognized this), effectively prevents the use of long-wavelength photons >300nm from patterning nanostructures barrier is developed and experimentally verified. This approach, which I refer to as Patterning via Optical Saturable Transitions (POST) has the potential for massive parallelism, enabling the creation of nanostructures and devices at a speed far surpassing what is currently possible with conventional optical lithographic techniques. The fundamental understanding of this technique goes beyond optical lithography in the semiconductor industry and is applicable to any area that requires the rapid patterning of large-area two or three-dimensional complex geometries. At a basic level, this research intertwines the fields of electrochemistry, material science, electrical engineering, optics, physics, and mechanical engineering with the goal of developing a novel super-resolution lithographic technique.

  4. Sensorial saturation for infants' pain.

    Science.gov (United States)

    Bellieni, Carlo Valerio; Tei, Monica; Coccina, Francesca; Buonocore, Giuseppe

    2012-04-01

    Sensorial saturation (SS) is a multisensorial stimulation consisting of delicate tactile, gustative, auditory and visual stimuli. This procedure consists of simultaneously: attracting the infant's attention by massaging the infant's face; speaking to the infant gently, but firmly, and instilling a sweet solution on the infant's tongue. We performed a systematic Medline search of for articles focusing on human neonatal studies related to SS. The search was performed within the last 10 years and was current as of January 2012. We retrieved 8 articles that used a complete form of SS and 2 articles with an incomplete SS. Data show that the use of SS is effective in relieving newborns' pain. Oral solution alone are less effective than SS, but the stimuli without oral sweet solution are ineffective. the partial forms of SS have some effectiveness, but minor than the complete SS. Only one article showed lack of SS as analgesic method, after endotracheal suctioning. SS can be used for all newborns undergoing blood samples or other minor painful procedures. It is more effective than oral sugar alone. SS also promotes interaction between nurse and infant and is a simple effective form of analgesia for the neonatal intensive care unit.

  5. Δ isobars and nuclear saturation

    Science.gov (United States)

    Ekström, A.; Hagen, G.; Morris, T. D.; Papenbrock, T.; Schwartz, P. D.

    2018-02-01

    We construct a nuclear interaction in chiral effective field theory with explicit inclusion of the Δ -isobar Δ (1232 ) degree of freedom at all orders up to next-to-next-to-leading order (NNLO). We use pion-nucleon (π N ) low-energy constants (LECs) from a Roy-Steiner analysis of π N scattering data, optimize the LECs in the contact potentials up to NNLO to reproduce low-energy nucleon-nucleon scattering phase shifts, and constrain the three-nucleon interaction at NNLO to reproduce the binding energy and point-proton radius of 4He. For heavier nuclei we use the coupled-cluster method to compute binding energies, radii, and neutron skins. We find that radii and binding energies are much improved for interactions with explicit inclusion of Δ (1232 ) , while Δ -less interactions produce nuclei that are not bound with respect to breakup into α particles. The saturation of nuclear matter is significantly improved, and its symmetry energy is consistent with empirical estimates.

  6. Large, non-saturating magnetoresistance in WTe2.

    Science.gov (United States)

    Ali, Mazhar N; Xiong, Jun; Flynn, Steven; Tao, Jing; Gibson, Quinn D; Schoop, Leslie M; Liang, Tian; Haldolaarachchige, Neel; Hirschberger, Max; Ong, N P; Cava, R J

    2014-10-09

    Magnetoresistance is the change in a material's electrical resistance in response to an applied magnetic field. Materials with large magnetoresistance have found use as magnetic sensors, in magnetic memory, and in hard drives at room temperature, and their rarity has motivated many fundamental studies in materials physics at low temperatures. Here we report the observation of an extremely large positive magnetoresistance at low temperatures in the non-magnetic layered transition-metal dichalcogenide WTe2: 452,700 per cent at 4.5 kelvins in a magnetic field of 14.7 teslas, and 13 million per cent at 0.53 kelvins in a magnetic field of 60 teslas. In contrast with other materials, there is no saturation of the magnetoresistance value even at very high applied fields. Determination of the origin and consequences of this effect, and the fabrication of thin films, nanostructures and devices based on the extremely large positive magnetoresistance of WTe2, will represent a significant new direction in the study of magnetoresistivity.

  7. Potential scattering in the presence of a static magnetic field and a radiation field of arbitrary polarization

    Science.gov (United States)

    Ferrante, G.; Zarcone, M.; Nuzzo, S.; McDowell, M. R. C.

    1982-05-01

    Expressions are obtained for the total cross sections for scattering of a charged particle by a potential in the presence of a static uniform magnetic field and a radiation field of arbitrary polarization. For a Coulomb field this is closely related to the time reverse of photoionization of a neutral atom in a magnetic field, including multiphoton effects off-resonance. The model is not applicable when the radiation energy approaches one of the quasi-Landau state separations. The effects of radiation field polarization are examined in detail.

  8. Third harmonic current injection into highly saturated multi-phase machines

    Directory of Open Access Journals (Sweden)

    Klute Felix

    2017-03-01

    Full Text Available One advantage of multi-phase machines is the possibility to use the third harmonic of the rotor flux for additional torque generation. This effect can be maximised for Permanent Magnet Synchronous Machines (PMSM with a high third harmonic content in the magnet flux. This paper discusses the effects of third harmonic current injection (THCI on a five-phase PMSM with a conventional magnet shape depending on saturation. The effects of THCI in five-phase machines are shown in a 2D FEM model in Ansys Maxwell verified by measurement results. The results of the FEM model are analytically analysed using the Park model. It is shown in simulation and measurement that the torque improvement by THCI increases significantly with the saturation level, as the amplitude of the third harmonic flux linkage increases with the saturation level but the phase shift of the rotor flux linkage has to be considered. This paper gives a detailed analysis of saturation mechanisms of PMSM, which can be used for optimizing the efficiency in operating points of high saturations, without using special magnet shapes.

  9. Research on evaluation method for water saturation of tight sandstone in Suxi region

    Science.gov (United States)

    Lv, Hong; Lai, Fuqiang; Chen, Liang; Li, Chao; Li, Jie; Yi, Heping

    2017-05-01

    The evaluation of irreducible water saturation is important for qualitative and quantitative prediction of residual oil distribution. However, it is to be improved for the accuracy of experimental measuring the irreducible water saturation and logging evaluation. In this paper, firstly the multi-functional core flooding experiment and the nuclear magnetic resonance centrifugation experiment are carried out in the west of Sulige gas field. Then, the influence was discussed about particle size, porosity and permeability on the water saturation. Finally, the evaluation model was established about irreducible water saturation and the evaluation of irreducible water saturation was carried out. The results show that the results of two experiments are both reliable. It is inversely proportional to the median particle size, porosity and permeability, and is most affected by the median particle size. The water saturation of the dry layer is higher than that of the general reservoir. The worse the reservoir property, the greater the water saturation. The test results show that the irreducible water saturation model can be used to evaluate the water floor.

  10. MAGNETIC CIRCUIT EQUIVALENT OF THE SYNCHRONOUS MOTOR WITH INCORPORATED MAGNETS

    Directory of Open Access Journals (Sweden)

    Fyong Le Ngo

    2015-01-01

    Full Text Available Magnetic circuitry computation is one of the central stages of designing a synchronous motor with incorporated magnets, which can be performed by means of a simplified method of the magnetic-circuits equivalent modeling. The article studies the magnetic circuit of the motor with the rotor-incorporated magnets, which includes four sectors: constant magnets with the field pole extension made of magnetically soft steel, magniflux dispersion sections containing air barriers and steel bridges; the air gap; the stator grooves, cogs and the frame yoke. The authors introduce an equivalent model of the magnetic circuit. High-energy magnets with a linear demagnetization curve are employed in the capacity of constant magnets. Two magnets create the magnetic flux for one pole. The decline of magnetic potential in the steel of the pole is negligible consequent on the admission that the poles magnetic inductivity µ = ∞. The rotor design provides for the air barriers and the steel bridges that close leakage flux. The induction-permeability curve linearization serves for the bridges magnetic saturation accountability and presents a polygonal line consisting of two linear sections. The estimation of the magnet circuit section including the cogs and the frame yoke is executed with account of the steel saturation, their magnetic conductivities thereat being dependent on the saturation rate. Relying on the equivalent model of the magnetic circuit, the authors deduce a system of two equations written from the first and the second Kirchhoff laws of the magnetic circuits. These equations allow solving two problems: specifying dimensions of the magnets by the preset value of the magnetic flow in the clearance and determining the clearance magnetic flow at the preset motor rotor-and-stator design.

  11. Femoral venous oxygen saturation is no surrogate for central venous oxygen saturation

    NARCIS (Netherlands)

    van Beest, Paul A.; van der Schors, Alice; Liefers, Henriëtte; Coenen, Ludo G. J.; Braam, Richard L.; Habib, Najib; Braber, Annemarije; Scheeren, Thomas W. L.; Kuiper, Michaël A.; Spronk, Peter E.

    2012-01-01

    Objective: The purpose of our study was to determine if central venous oxygen saturation and femoral venous oxygen saturation can be used interchangeably during surgery and in critically ill patients. Design: Prospective observational controlled study. Setting: Nonacademic university-affiliated

  12. Measurement of the saturation magnetostriction constant of amorphous wire

    International Nuclear Information System (INIS)

    Mitra, A.; Vazquez, M.

    1990-01-01

    Measurement of the magnetostriction constant of amorphous wire by conventional techniques is very difficult because of its small diameter. However, accurate determination of the magnetostriction constant is important in the study of amorphous wires. Here the saturation magnetostriction constant (λ s ) for a low-magnetostriction amorphous wire of nominal composition (Fe 6.3 Co 92.7 Nb 1 ) 77.5 Si 7.5 B 15 has been determined by means of the small-angle magnetization-rotation method. λ s has been evaluated to be 2.1x10 -7 for its as-received state. The dependence of thermal treatment is also reported

  13. Ultrafast THz Saturable Absorption in Semiconductors

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hoffmann, Matthias C.

    2011-01-01

    We demonstrate THz saturable absorption in n-doped semiconductors GaAs, GaP, and Ge in a nonlinear THz time-domain spectroscopy experiment. Saturable absorption is caused by sample conductivity modulation due to electron heating and satellite valley scattering in the field of a strong THz pulse....

  14. Determination of saturation functions and wettability for chalk based on measured fluid saturations

    Energy Technology Data Exchange (ETDEWEB)

    Olsen, D.; Bech, N.; Moeller Nielsen, C.

    1998-08-01

    The end effect of displacement experiments on low permeable porous media is used for determination of relative permeability functions and capillary pressure functions. Saturation functions for a drainage process are determined from a primary drainage experiment. A reversal of the flooding direction creates an intrinsic imbibition process in the sample, which enables determination if imbibition saturation functions. The saturation functions are determined by a parameter estimation technique. Scanning effects are modelled by the method of Killough. Saturation profiles are determined by NMR. (au)

  15. Recipe for residual oil saturation determination

    Energy Technology Data Exchange (ETDEWEB)

    Guillory, A.J.; Kidwell, C.M.

    1979-01-01

    In 1978, Shell Oil Co., in conjunction with the US Department of Energy, conducted a residual oil saturation study in a deep, hot high-pressured Gulf Coast Reservoir. The work was conducted prior to initiation of CO/sub 2/ tertiary recovery pilot. Many problems had to be resolved prior to and during the residual oil saturation determination. The problems confronted are outlined such that the procedure can be used much like a cookbook in designing future studies in similar reservoirs. Primary discussion centers around planning and results of a log-inject-log operation used as a prime method to determine the residual oil saturation. Several independent methods were used to calculate the residual oil saturation in the subject well in an interval between 12,910 ft (3935 m) and 12,020 ft (3938 m). In general, these numbers were in good agreement and indicated a residual oil saturation between 22% and 24%. 10 references.

  16. MAGNETIC WOVEN FABRICS - PHYSICAL AND MAGNETIC PROPERTIES

    Directory of Open Access Journals (Sweden)

    GROSU Marian C

    2015-05-01

    Full Text Available A coated material is a composite structure that consists of at least two components: base material and coating layer. The purpose of coating is to provide special properties to base material, with potential to be applied in EMI shielding and diverse smart technical fields. This paper reports the results of a study about some physical and magnetic properties of coated woven fabrics made from cotton yarns with fineness of 17 metric count. For this aim, a plain woven fabric was coated with a solution hard magnetic polymer based. As hard magnetic powder, barium hexaferrite (BaFe12O19 was selected. The plain woven fabric used as base has been coated with five solutions having different amounts of hard magnetic powder (15% - 45% in order to obtain five different magnetic woven fabrics. A comparison of physical properties regarding weight (g/m2, thickness (mm, degree of charging (% and magnetic properties of magnetic woven samples were presented. Saturation magnetizing (emu/g, residual magnetizing (emu/g and coercive force (kA/m of pure hard magnetic powder and woven fabrics have been studied as hysteresis characteristics. The magnetic properties of the woven fabrics depend on the mass percentage of magnetic powder from coating solution. Also, the residual magnetism and coercive field of woven fabrics represents only a part of bulk barium hexafferite residual magnetism and coercive field.

  17. Educational simulator app and web page for exploring Nuclear and Compass Magnetic Resonance

    DEFF Research Database (Denmark)

    Hanson, Lars G.

    experimentation that improves understanding of basic MR phenomena. The simulator is used to introduce and explore electromagnetism, magnetic dipoles, static and radiofrequency fields, Compass MR, the free induction decay (FID), relaxation, the Fourier transform (FFT), the resonance condition, spin, precession......, the Larmor equation, Nuclear MR, resonant excitation (linear and quadrature), and off-resonance effects. Methods and implementation: The simulator is a complete HTML5/JavaScript[1,2] rewrite of the JavaCompass[3] so it now executes in modern browsers with no additional software needed. Spin dynamics...

  18. [The water content reference material of water saturated octanol].

    Science.gov (United States)

    Wang, Haifeng; Ma, Kang; Zhang, Wei; Li, Zhanyuan

    2011-03-01

    The national standards of biofuels specify the technique specification and analytical methods. A water content certified reference material based on the water saturated octanol was developed in order to satisfy the needs of the instrument calibration and the methods validation, assure the accuracy and consistency of results in water content measurements of biofuels. Three analytical methods based on different theories were employed to certify the water content of the reference material, including Karl Fischer coulometric titration, Karl Fischer volumetric titration and quantitative nuclear magnetic resonance. The consistency of coulometric and volumetric titration was achieved through the improvement of methods. The accuracy of the certified result was improved by the introduction of the new method of quantitative nuclear magnetic resonance. Finally, the certified value of reference material is 4.76% with an expanded uncertainty of 0.09%.

  19. Studies on the effect of the axial magnetic field on the x-ray bremsstrahlung in a 2.45 GHz permanent magnet microwave ion source.

    Science.gov (United States)

    Kumar, Narender; Rodrigues, G; Lakshmy, P S; Baskaran, R; Mathur, Y; Ahuja, R; Kanjilal, D

    2014-02-01

    A compact microwave ion source has been designed and developed for operation at a frequency of 2.45 GHz. The axial magnetic field is based on two permanent magnet rings, operating in the "off-resonance" mode and is tunable by moving the permanent magnets. In order to understand the electron energy distribution function, x-ray bremsstrahlung has been measured in the axial direction. Simulation studies on the x-ray bremsstrahlung have been carried out to compare with the experimental results. The effect of the axial magnetic field with respect to the microwave launching position and the position of the extraction electrode on the x-ray bremsstrahlung have been studied.

  20. Assessing species saturation: conceptual and methodological challenges.

    Science.gov (United States)

    Olivares, Ingrid; Karger, Dirk N; Kessler, Michael

    2018-05-07

    Is there a maximum number of species that can coexist? Intuitively, we assume an upper limit to the number of species in a given assemblage, or that a lineage can produce, but defining and testing this limit has proven problematic. Herein, we first outline seven general challenges of studies on species saturation, most of which are independent of the actual method used to assess saturation. Among these are the challenge of defining saturation conceptually and operationally, the importance of setting an appropriate referential system, and the need to discriminate among patterns, processes and mechanisms. Second, we list and discuss the methodological approaches that have been used to study species saturation. These approaches vary in time and spatial scales, and in the variables and assumptions needed to assess saturation. We argue that assessing species saturation is possible, but that many studies conducted to date have conceptual and methodological flaws that prevent us from currently attaining a good idea of the occurrence of species saturation. © 2018 Cambridge Philosophical Society.

  1. Saturation and forward jets at HERA

    International Nuclear Information System (INIS)

    Marquet, C.; Peschanski, R.; Royon, C.

    2004-01-01

    We analyse forward-jet production at HERA in the framework of the Golec-Biernat and Wusthoff saturation models. We obtain a good description of the forward-jet cross-sections measured by the H1 and ZEUS Collaborations in the two-hard-scale region (k T∼ Q >> Λ QCD ) with two different parametrizations with either significant or weak saturation effects. The weak saturation parametrization gives a scale compatible with the one found for the proton structure function F2. We argue that Mueller-Navelet jets at the Tevatron and the LHC could help distinguishing between both options

  2. Scintillation probe with photomultiplier tube saturation indicator

    International Nuclear Information System (INIS)

    Ruch, J.F.; Urban, D.J.

    1996-01-01

    A photomultiplier tube saturation indicator is formed by supplying a supplemental light source, typically an light emitting diode (LED), adjacent to the photomultiplier tube. A switch allows the light source to be activated. The light is forwarded to the photomultiplier tube by an optical fiber. If the probe is properly light tight, then a meter attached to the indicator will register the light from the LED. If the probe is no longer light tight, and the saturation indicator is saturated, no signal will be registered when the LED is activated. 2 figs

  3. Magnetic resonance annual, 1988

    International Nuclear Information System (INIS)

    Kressel, H.Y.

    1987-01-01

    This book features reviews of high-resolution MRI of the knee, MRI of the normal and ischmeic hip, MRI of the heart, and temporomandibular joint imaging, as well as thorough discussion on artifacts in magnetic resonance imaging. Contributors consider the clinical applications of gadolinium-DTPA in magnetic resonance imaging and the clinical use of partial saturation and saturation recovery sequences. Timely reports assess the current status of rapid MRI and describe a new rapid gated cine MRI technique. Also included is an analysis of cerebrospinal fluid flow effects during MRI of the central nervous system

  4. Minimum K_2,3-saturated Graphs

    OpenAIRE

    Chen, Ya-Chen

    2010-01-01

    A graph is K_{2,3}-saturated if it has no subgraph isomorphic to K_{2,3}, but does contain a K_{2,3} after the addition of any new edge. We prove that the minimum number of edges in a K_{2,3}-saturated graph on n >= 5 vertices is sat(n, K_{2,3}) = 2n - 3.

  5. Semiconductor saturable absorbers for ultrafast THz signals

    DEFF Research Database (Denmark)

    Hoffmann, Matthias C.; Turchinovich, Dmitry

    We demonstrate saturable absorber behavior of n-type semiconductors in the THz frequency range using nonlinear THz spectroscopy. Further, we observe THz pulse shortening and increase of the group refractive index at high field strengths.......We demonstrate saturable absorber behavior of n-type semiconductors in the THz frequency range using nonlinear THz spectroscopy. Further, we observe THz pulse shortening and increase of the group refractive index at high field strengths....

  6. Ultrafast THz Saturable Absorption in Doped Semiconductors

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hoffmann, Matthias C.

    2011-01-01

    We demonstrate ultrafast THz saturable absorption in n-doped semiconductors by nonlinear THz time-domain spectroscopy. This effect is caused by the semiconductor conductivity modulation due to electron heating and satellite-valley scattering in strong THz fields.......We demonstrate ultrafast THz saturable absorption in n-doped semiconductors by nonlinear THz time-domain spectroscopy. This effect is caused by the semiconductor conductivity modulation due to electron heating and satellite-valley scattering in strong THz fields....

  7. SATURATED ZONE IN-SITU TESTING

    Energy Technology Data Exchange (ETDEWEB)

    P.W. REIMUS

    2004-11-08

    The purpose of this scientific analysis is to document the results and interpretations of field experiments that test and validate conceptual flow and radionuclide transport models in the saturated zone (SZ) near Yucca Mountain, Nevada. The test interpretations provide estimates of flow and transport parameters used in the development of parameter distributions for total system performance assessment (TSPA) calculations. These parameter distributions are documented in ''Site-Scale Saturated Zone Flow Model (BSC 2004 [DIRS 170037]), Site-Scale Saturated Zone Transport'' (BSC 2004 [DIRS 170036]), Saturated Zone Colloid Transport (BSC 2004 [DIRS 170006]), and ''Saturated Zone Flow and Transport Model Abstraction'' (BSC 2004 [DIRS 170042]). Specifically, this scientific analysis contributes the following to the assessment of the capability of the SZ to serve as part of a natural barrier for waste isolation for the Yucca Mountain repository system: (1) The bases for selection of conceptual flow and transport models in the saturated volcanics and the saturated alluvium located near Yucca Mountain. (2) Results and interpretations of hydraulic and tracer tests conducted in saturated fractured volcanics at the C-wells complex near Yucca Mountain. The test interpretations include estimates of hydraulic conductivities, anisotropy in hydraulic conductivity, storativities, total porosities, effective porosities, longitudinal dispersivities, matrix diffusion mass transfer coefficients, matrix diffusion coefficients, fracture apertures, and colloid transport parameters. (3) Results and interpretations of hydraulic and tracer tests conducted in saturated alluvium at the Alluvial Testing Complex (ATC) located at the southwestern corner of the Nevada Test Site (NTS). The test interpretations include estimates of hydraulic conductivities, storativities, total porosities, effective porosities, longitudinal dispersivities, matrix diffusion mass

  8. SATURATED ZONE IN-SITU TESTING

    International Nuclear Information System (INIS)

    REIMUS, P.W.

    2004-01-01

    The purpose of this scientific analysis is to document the results and interpretations of field experiments that test and validate conceptual flow and radionuclide transport models in the saturated zone (SZ) near Yucca Mountain, Nevada. The test interpretations provide estimates of flow and transport parameters used in the development of parameter distributions for total system performance assessment (TSPA) calculations. These parameter distributions are documented in ''Site-Scale Saturated Zone Flow Model (BSC 2004 [DIRS 170037]), Site-Scale Saturated Zone Transport'' (BSC 2004 [DIRS 170036]), Saturated Zone Colloid Transport (BSC 2004 [DIRS 170006]), and ''Saturated Zone Flow and Transport Model Abstraction'' (BSC 2004 [DIRS 170042]). Specifically, this scientific analysis contributes the following to the assessment of the capability of the SZ to serve as part of a natural barrier for waste isolation for the Yucca Mountain repository system: (1) The bases for selection of conceptual flow and transport models in the saturated volcanics and the saturated alluvium located near Yucca Mountain. (2) Results and interpretations of hydraulic and tracer tests conducted in saturated fractured volcanics at the C-wells complex near Yucca Mountain. The test interpretations include estimates of hydraulic conductivities, anisotropy in hydraulic conductivity, storativities, total porosities, effective porosities, longitudinal dispersivities, matrix diffusion mass transfer coefficients, matrix diffusion coefficients, fracture apertures, and colloid transport parameters. (3) Results and interpretations of hydraulic and tracer tests conducted in saturated alluvium at the Alluvial Testing Complex (ATC) located at the southwestern corner of the Nevada Test Site (NTS). The test interpretations include estimates of hydraulic conductivities, storativities, total porosities, effective porosities, longitudinal dispersivities, matrix diffusion mass transfer coefficients, and colloid

  9. A 70 kV solid-state high voltage pulse generator based on saturable pulse transformer.

    Science.gov (United States)

    Fan, Xuliang; Liu, Jinliang

    2014-02-01

    High voltage pulse generators are widely applied in many fields. In recent years, solid-state and operating at repetitive mode are the most important developing trends of high voltage pulse generators. A solid-state high voltage pulse generator based on saturable pulse transformer is proposed in this paper. The proposed generator is consisted of three parts. They are charging system, triggering system, and the major loop. Saturable pulse transformer is the key component of the whole generator, which acts as a step-up transformer and main switch during working process of this generator. The circuit and working principles of the proposed pulse generator are introduced first in this paper, and the saturable pulse transformer used in this generator is introduced in detail. Circuit of the major loop is simulated to verify the design of the system. Demonstration experiments are carried out, and the results show that when the primary energy storage capacitor is charged to a high voltage, such as 2.5 kV, a voltage with amplitude of 86 kV can be achieved on the secondary winding. The magnetic core of saturable pulse transformer is saturated deeply and the saturable inductance of the secondary windings is very small. The switch function of the saturable pulse transformer can be realized ideally. Therefore, a 71 kV output voltage pulse is formed on the load. Moreover, the magnetic core of the saturable pulse transformer can be reset automatically.

  10. Modified small angle magnetization rotation method in multilayer magnetic microwires

    International Nuclear Information System (INIS)

    Torrejon, J.; Badini, G.; Pirota, K.; Vazquez, M.

    2007-01-01

    The small angle magnetization rotation (SAMR) technique is a widely used method to quantify magnetostriction in elongated ultrasoft magnetic materials. In the present work, we introduce significant optimization of the method, particularly simplification of the required equipment, profiting of the very peculiar characteristics of a recently introduced family of multilayer magnetic microwires consisting of a soft magnetic core, insulating intermediate layer and a hard magnetic outer layer. The introduced modified SAMR method is used not only to determine the saturation magnetostriction constant of the soft magnetic nucleus but also the magnetoelastic and magnetostatic coupling. This new method has a great potential in multifunctional sensor applications

  11. Oscillatory interlayer magnetic coupling and induced magnetism in ...

    Indian Academy of Sciences (India)

    Unknown

    lating interlayer magnetic coupling (IMC) (Grunberg et al 1986; Parkin et al 1990; Unguris et al 1991) and giant magnetoresistance (GMR). Such oscillations in interlayer magnetic coupling and the saturation magnetoresistance were reported by Parkin et al (1990) with a period 15–. 20 Å in Fe/Cr, Co/Cr, Co/Ru multilayers.

  12. Lipid order, saturation and surface property relationships: a study of human meibum saturation.

    Science.gov (United States)

    Mudgil, Poonam; Borchman, Douglas; Yappert, Marta C; Duran, Diana; Cox, Gregory W; Smith, Ryan J; Bhola, Rahul; Dennis, Gary R; Whitehall, John S

    2013-11-01

    Tear film stability decreases with age however the cause(s) of the instability are speculative. Perhaps the more saturated meibum from infants may contribute to tear film stability. The meibum lipid phase transition temperature and lipid hydrocarbon chain order at physiological temperature (33 °C) decrease with increasing age. It is reasonable that stronger lipid-lipid interactions could stabilize the tear film since these interactions must be broken for tear break up to occur. In this study, meibum from a pool of adult donors was saturated catalytically. The influence of saturation on meibum hydrocarbon chain order was determined by infrared spectroscopy. Meibum is in an anhydrous state in the meibomian glands and on the surface of the eyelid. The influence of saturation on the surface properties of meibum was determined using Langmuir trough technology. Saturation of native human meibum did not change the minimum or maximum values of hydrocarbon chain order so at temperatures far above or below the phase transition of human meibum, saturation does not play a role in ordering or disordering the lipid hydrocarbon chains. Saturation did increase the phase transition temperature in human meibum by over 20 °C, a relatively high amount. Surface pressure-area studies showing the late take off and higher maximum surface pressure of saturated meibum compared to native meibum suggest that the saturated meibum film is quite molecularly ordered (stiff molecular arrangement) and elastic (molecules are able to rearrange during compression and expansion) compared with native meibum films which are more fluid agreeing with the infrared spectroscopic results of this study. In saturated meibum, the formation of compacted ordered islands of lipids above the surfactant layer would be expected to decrease the rate of evaporation compared to fluid and more loosely packed native meibum. Higher surface pressure observed with films of saturated meibum compared to native meibum

  13. Interger multiplication with overflow detection or saturation

    Energy Technology Data Exchange (ETDEWEB)

    Schulte, M.J.; Balzola, P.I.; Akkas, A.; Brocato, R.W.

    2000-01-11

    High-speed multiplication is frequently used in general-purpose and application-specific computer systems. These systems often support integer multiplication, where two n-bit integers are multiplied to produce a 2n-bit product. To prevent growth in word length, processors typically return the n least significant bits of the product and a flag that indicates whether or not overflow has occurred. Alternatively, some processors saturate results that overflow to the most positive or most negative representable number. This paper presents efficient methods for performing unsigned or two's complement integer multiplication with overflow detection or saturation. These methods have significantly less area and delay than conventional methods for integer multiplication with overflow detection and saturation.

  14. Tracking Controller for Intrinsic Output Saturated Systems in Presence of Amplitude and Rate Input Saturations

    DEFF Research Database (Denmark)

    Chater, E.; Giri, F.; Guerrero, Josep M.

    2014-01-01

    We consider the problem of controlling plants that are subject to multiple saturation constraints. Especially, we are interested in linear systems whose input is subject to amplitude and rate constraints of saturation type. Furthermore, the considered systems output is also subject to an intrinsi...

  15. Studies of non-isothermal flow in saturated and partially saturated porous media

    International Nuclear Information System (INIS)

    Ho, C.K.; Maki, K.S.; Glass, R.J.

    1993-01-01

    Physical and numerical experiments have been performed to investigate the behavior of nonisothermal flow in two-dimensional saturated and partially saturated porous media. The physical experiments were performed to identify non-isothermal flow fields and temperature distributions in fully saturated, half-saturated, and residually saturated two-dimensional porous media with bottom heating and top cooling. Two counter-rotating liquid-phase convective cells were observed to develop in the saturated regions of all three cases. Gas-phase convection was also evidenced in the unsaturated regions of the partially saturated experiments. TOUGH2 numerical simulations of the saturated case were found to be strongly dependent on the assumed boundary conditions of the physical system. Models including heat losses through the boundaries of the test cell produced temperature and flow fields that were in better agreement with the observed temperature and flow fields than models that assumed insulated boundary conditions. A sensitivity analysis also showed that a reduction of the bulk permeability of the porous media in the numerical simulations depressed the effects of convection, flattening the temperature profiles across the test cell

  16. Femoral venous oxygen saturation is no surrogate for central venous oxygen saturation

    NARCIS (Netherlands)

    van Beest, Paul A.; van der Schors, Alice; Liefers, Henriette; Coenen, Ludo G. J.; Braam, Richard L.; Habib, Najib; Braber, Annemarije; Scheeren, Thomas W. L.; Kuiper, Michael A.; Spronk, Peter E.

    2012-01-01

    Objective:  The purpose of our study was to determine if central venous oxygen saturation and femoral venous oxygen saturation can be used interchangeably during surgery and in critically ill patients. Design:  Prospective observational controlled study. Setting:  Nonacademic university-affiliated

  17. Edge effect in charged-particle analyzing magnets

    NARCIS (Netherlands)

    Braams, C.M.

    The manner in which local saturation of pole pieces with sharp edges affects the fall-off of the magnetic induction in the fringing-field region is discussed and measured. Local saturation appears to set in at a field strength well below that at which over-all saturation of the pole pieces becomes

  18. Saturated poroelastic actuators generated by topology optimization

    DEFF Research Database (Denmark)

    Andreasen, Casper Schousboe; Sigmund, Ole

    2011-01-01

    the coupling of internal fluid pressure and elastic shear stresses a slab of the optimized porous material deflects/deforms when a pressure is imposed and an actuator is created. Several phenomenologically based constraints are imposed in order to get a stable force transmitting actuator.......In this paper the fluid-structure interaction problem of a saturated porous media is considered. The pressure coupling properties of porous saturated materials change with the microstructure and this is utilized in the design of an actuator using a topology optimized porous material. By maximizing...

  19. High speed drying of saturated steam

    International Nuclear Information System (INIS)

    Marty, C.; Peyrelongue, J.P.

    1993-01-01

    This paper describes the development of the drying process for the saturated steam used in the PWR nuclear plant turbines in order to prevent negative effects of water on turbine efficiency, maintenance costs and equipment lifetime. The high speed drying concept is based on rotating the incoming saturated steam in order to separate water which is more denser than the steam; the water film is then extracted through an annular slot. A multicellular modular equipment has been tested. Applications on high and low pressure extraction of various PWR plants are described (Bugey, Loviisa)

  20. Site-Scale Saturated Zone Flow Model

    International Nuclear Information System (INIS)

    G. Zyvoloski

    2003-01-01

    The purpose of this model report is to document the components of the site-scale saturated-zone flow model at Yucca Mountain, Nevada, in accordance with administrative procedure (AP)-SIII.lOQ, ''Models''. This report provides validation and confidence in the flow model that was developed for site recommendation (SR) and will be used to provide flow fields in support of the Total Systems Performance Assessment (TSPA) for the License Application. The output from this report provides the flow model used in the ''Site-Scale Saturated Zone Transport'', MDL-NBS-HS-000010 Rev 01 (BSC 2003 [162419]). The Site-Scale Saturated Zone Transport model then provides output to the SZ Transport Abstraction Model (BSC 2003 [164870]). In particular, the output from the SZ site-scale flow model is used to simulate the groundwater flow pathways and radionuclide transport to the accessible environment for use in the TSPA calculations. Since the development and calibration of the saturated-zone flow model, more data have been gathered for use in model validation and confidence building, including new water-level data from Nye County wells, single- and multiple-well hydraulic testing data, and new hydrochemistry data. In addition, a new hydrogeologic framework model (HFM), which incorporates Nye County wells lithology, also provides geologic data for corroboration and confidence in the flow model. The intended use of this work is to provide a flow model that generates flow fields to simulate radionuclide transport in saturated porous rock and alluvium under natural or forced gradient flow conditions. The flow model simulations are completed using the three-dimensional (3-D), finite-element, flow, heat, and transport computer code, FEHM Version (V) 2.20 (software tracking number (STN): 10086-2.20-00; LANL 2003 [161725]). Concurrently, process-level transport model and methodology for calculating radionuclide transport in the saturated zone at Yucca Mountain using FEHM V 2.20 are being

  1. Saturated Zone Colloid-Facilitated Transport

    International Nuclear Information System (INIS)

    Wolfsberg, A.; Reimus, P.

    2001-01-01

    The purpose of the Saturated Zone Colloid-Facilitated Transport Analysis and Modeling Report (AMR), as outlined in its Work Direction and Planning Document (CRWMS MandO 1999a), is to provide retardation factors for colloids with irreversibly-attached radionuclides, such as plutonium, in the saturated zone (SZ) between their point of entrance from the unsaturated zone (UZ) and downgradient compliance points. Although it is not exclusive to any particular radionuclide release scenario, this AMR especially addresses those scenarios pertaining to evidence from waste degradation experiments, which indicate that plutonium and perhaps other radionuclides may be irreversibly attached to colloids. This report establishes the requirements and elements of the design of a methodology for calculating colloid transport in the saturated zone at Yucca Mountain. In previous Total Systems Performance Assessment (TSPA) analyses, radionuclide-bearing colloids were assumed to be unretarded in their migration. Field experiments in fractured tuff at Yucca Mountain and in porous media at other sites indicate that colloids may, in fact, experience retardation relative to the mean pore-water velocity, suggesting that contaminants associated with colloids should also experience some retardation. Therefore, this analysis incorporates field data where available and a theoretical framework when site-specific data are not available for estimating plausible ranges of retardation factors in both saturated fractured tuff and saturated alluvium. The distribution of retardation factors for tuff and alluvium are developed in a form consistent with the Performance Assessment (PA) analysis framework for simulating radionuclide transport in the saturated zone. To improve on the work performed so far for the saturated-zone flow and transport modeling, concerted effort has been made in quantifying colloid retardation factors in both fractured tuff and alluvium. The fractured tuff analysis used recent data

  2. On the saturation of astrophysical dynamos

    DEFF Research Database (Denmark)

    Dorch, Bertil; Archontis, Vasilis

    2004-01-01

    In the context of astrophysical dynamos we illustrate that the no-cosines flow, with zero mean helicity, can drive fast dynamo action and we study the dynamo's mode of operation during both the linear and non-linear saturation regimes. It turns out that in addition to a high growth rate in the li......In the context of astrophysical dynamos we illustrate that the no-cosines flow, with zero mean helicity, can drive fast dynamo action and we study the dynamo's mode of operation during both the linear and non-linear saturation regimes. It turns out that in addition to a high growth rate...

  3. Nonlinear saturation of the Rayleigh Taylor instability

    International Nuclear Information System (INIS)

    Das, A.; Mahajan, S.; Kaw, P.; Sen, A.; Benkadda, S.; Verga, A.

    1997-01-01

    The problem of the nonlinear saturation of the 2 dimensional Rayleigh Taylor instability is re-examined to put various earlier results in a proper perspective. The existence of a variety of final states can be attributed to the differences in the choice of boundary conditions and initial conditions in earlier numerical modeling studies. Our own numerical simulations indicate that the RT instability saturates by the self consistent generation of shear flow even in situations (with periodic boundaries) where, in principle, an infinite amount of gravitational energy can be tapped. Such final states can be achieved for suitable values of the Prandtl number. (author)

  4. Saturable absorption in detonation nanodiamond dispersions

    Science.gov (United States)

    Vanyukov, Viatcheslav; Mikheev, Gennady; Mogileva, Tatyana; Puzyr, Alexey; Bondar, Vladimir; Lyashenko, Dmitry; Chuvilin, Andrey

    2017-07-01

    We report on a saturable absorption in aqueous dispersions of nanodiamonds with femtosecond laser pulse excitation at a wavelength of 795 nm. The open aperture Z-scan experiments reveal that in a wide range of nanodiamond particle sizes and concentrations, a light-induced increase of transmittance occurs. The transmittance increase originates from the saturation of light absorption and is associated with a light absorption at 1.5 eV by graphite and dimer chains (Pandey dimer chains). The obtained key nonlinear parameters of nanodiamond dispersions are compared with those of graphene and carbon nanotubes, which are widely used for the mode-locking.

  5. Fat-saturated post gadolinium T1 imaging of the brain in multiple sclerosis

    International Nuclear Information System (INIS)

    Al-Saeed, Osama; Sheikh, Mehraj; Ismail, Mohammed; Athyal, Reji

    2011-01-01

    Background Magnetic resonance imaging (MRI) is of vital importance in the diagnosis and follow-up of patients with multiple sclerosis (MS). Imaging sequences better demonstrating enhancing lesions can help in detecting active MS plaques. Purpose To evaluate the role of fat-saturated gadolinium-enhanced T1-weighted (T1W) images of the brain in MS and to assess the benefit of performing this additional sequence in the detection of enhancing lesions. Material and Methods In a prospective study over a six-month period, 70 consecutive patients with clinically diagnosed MS were enrolled. These constituted 14 male and 56 female patients between the ages of 21 and 44 years. All the patients underwent brain MRIs on a 1.5 Tesla Magnet. Gadolinium-enhanced T1 images with and without fat saturation were compared and results were recorded and analyzed using a conspicuity score and McNemar test. Results There were a total of 157 lesions detected in 70 patients on post-contrast T1W fat-saturated images compared with 139 lesions seen on the post-contrast T1W fast spin-echo (FSE) images. This was because 18 of the lesions (11.5%) were only seen on the fat-saturated images. In addition, 15 lesions were more conspicuous on the fat saturation sequence (9.5%). The total conspicuity score obtained, including all the lesions, was 2.24 +/-0.60 (SD). Using the two-tailed McNemar test for quantitative analysis, the P value obtained was <0.0001. Conclusion T1W fat-saturated gadolinium-enhanced images show better lesion enhancement than T1W images without fat saturation

  6. Chemical Exchange Saturation Transfer (CEST): what is in a name and what isn’t?

    Science.gov (United States)

    van Zijl, Peter C.M.; Yadav, Nirbhay N.

    2011-01-01

    Chemical exchange saturation transfer (CEST) imaging is a relatively new MRI contrast approach in which exogenous or endogenous compounds containing either exchangeable protons or exchangeable molecules are selectively saturated and, after transfer of this saturation, detected indirectly through the water signal with enhanced sensitivity. The focus of this review is on basic MR principles underlying CEST and similarities to and differences with conventional magnetization transfer contrast (MTC). In CEST MRI, transfer of magnetization is studied in mobile compounds instead of semisolids. Similar to MTC, CEST has contributions of both chemical exchange and dipolar cross-relaxation, but the latter can often be neglected if exchange is fast. Contrary to MTC, CEST imaging requires sufficiently slow exchange on the MR time scale to allow selective irradiation of the protons of interest. As a consequence, magnetic labeling is not limited to radio-frequency saturation but can be expanded with slower frequency-selective approaches such as inversion, gradient dephasing and frequency labeling. The basic theory, design criteria, and experimental issues for exchange transfer imaging are discussed. A new classification for CEST agents based on exchange type is proposed. The potential of this young field is discussed, especially with respect to in vivo application and translation to humans. PMID:21337419

  7. Oxygen general saturation after bronchography under general ...

    African Journals Online (AJOL)

    Thirty-six patients undergoing bronchography or bronchoscopy under general anaesthesia were continuously monitored by pulse oximetry for 5 hours after these procedures. Significant falls in oxygen saturation were observed in the first hour and were of most clinical relevance in patients with preexisting pulmonary ...

  8. Wave propagation in thermoelastic saturated porous medium

    Indian Academy of Sciences (India)

    the existence and propagation of four waves in the medium. Three of the waves are ... predicted infinite speed for propagation of ther- mal signals. Lord and ..... saturated reservoir rock (North-sea Sandstone) is chosen for the numerical model ...

  9. Saturated fat, carbohydrates and cardiovascular disease

    NARCIS (Netherlands)

    Kuipers, R. S.; de Graaf, D. J.; Luxwolda, M. F.; Muskiet, M. H. A.; Dijck-Brouwer, D. A. J.; Muskiet, F. A. J.

    The dietary intake of saturated fatty acids (SAFA) is associated with a modest increase in serum total cholesterol, but not with cardiovascular disease (CVD). Replacing dietary SAFA with carbohydrates (CHO), notably those with a high glycaemic index, is associated with an increase in CVD risk in

  10. Saturation at Low X and Nonlinear Evolution

    International Nuclear Information System (INIS)

    Stasto, A.M.

    2002-01-01

    In this talk the results of the analytical and numerical analysis of the nonlinear Balitsky-Kovchegov equation are presented. The characteristic BFKL diffusion into infrared regime is suppressed by the generation of the saturation scale Q s . We identify the scaling and linear regimes for the solution. We also study the impact of subleading corrections onto the nonlinear evolution. (author)

  11. Saturation of bentonite dependent upon temperature

    International Nuclear Information System (INIS)

    Hausmannova, Lucie; Vasicek, Radek

    2010-01-01

    Document available in extended abstract form only. The fundamental idea behind the long-term safe operation of a deep repository is the use of the Multi-barrier system principle. Barriers may well differ according to the type of host rock in which the repository is located. It is assumed that the buffer in the granitic host rock environment will consist of swelling clays which boast the ideal properties for such a function i.e. low permeability, high swelling pressure, self-healing ability etc. all of which are affected primarily by mineralogy and dry density. Water content plays a crucial role in the activation of swelling pressure as well as, subsequently, in the potential self healing of the various contact areas of the numerous buffer components made from bentonite. In the case of a deep repository, a change in water content is not only connected with the possible intake of water from the host rock, but also with its redistribution owing to changes in temperature after the insertion of the heat source (disposal waste package containing spent fuel) into the repository 'nest'. The principal reason for the experimental testing of this high dry density material is the uncertainty with regard to its saturation ability (final water content or the degree of saturation) at higher temperatures. The results of the Mock-Up-CZ experiment showed that when the barrier is constantly supplied with a saturation medium over a long time period the water content in the barrier as well as the degree of saturation settle independently of temperature. The Mock-Up-CZ experiment was performed at temperatures of 30 deg. - 90 deg. C in the barrier; therefore it was decided to experimentally verify this behaviour by means of targeted laboratory tests. A temperature of 110 deg. C was added to the set of experimental temperatures resulting in samples being tested at 25 deg. C, 95 deg. C and 110 deg. C. The degree of saturation is defined as the ratio of pore water volume to pore

  12. Two-beam interaction in saturable media

    DEFF Research Database (Denmark)

    Schjødt-Eriksen, Jens; Schmidt, Michel R.; Juul Rasmussen, Jens

    1998-01-01

    The dynamics of two coupled soliton solutions of the nonlinear Schrodinger equation with a saturable nonlinearity is investigated It is shown by means of a variational method and by direct numerical calculations that two well-separated solitons can orbit around each other, if their initial velocity...

  13. Oxygenation of saturated and unsaturated hydrocarbons with ...

    Indian Academy of Sciences (India)

    Unknown

    Oxygenation of saturated and unsaturated hydrocarbons with sodium periodate. 431. Table 1. Competitive oxygenation of tetralin and cyclooctene with sodium periodate catalyzed by different manga- .... Teacher Education University. My grateful thanks also extend to Dr D Mohajer for his useful sugges- tions. References. 1.

  14. Multiscale optimization of saturated poroelastic actuators

    DEFF Research Database (Denmark)

    Andreasen, Casper Schousboe; Sigmund, Ole

    A multiscale method for optimizing the material micro structure in a macroscopically heterogeneous saturated poroelastic media with respect to macro properties is presented. The method is based on topology optimization using the homogenization technique, here applied to the optimization of a bi...

  15. Synthesis and characterization of saturated polyester and ...

    Indian Academy of Sciences (India)

    but which can actually be used for processes, which pro- duce interesting ... ing the synthesis of saturated polyester (from GPET waste). This has been done for the .... The solid product obtained from the glycolysis of PET was bis(hydroxy ethyl ...

  16. Microscopic analysis of saturable absorbers: Semiconductor saturable absorber mirrors versus graphene

    Energy Technology Data Exchange (ETDEWEB)

    Hader, J.; Moloney, J. V. [Nonlinear Control Strategies, Inc., 3542 N. Geronimo Ave., Tucson, Arizona 85705 (United States); College of Optical Sciences, University of Arizona, Tucson, Arizona 85721 (United States); Yang, H.-J.; Scheller, M. [College of Optical Sciences, University of Arizona, Tucson, Arizona 85721 (United States); Koch, S. W. [Department of Physics and Materials Sciences Center, Philipps Universität Marburg, Renthof 5, 35032 Marburg (Germany)

    2016-02-07

    Fully microscopic many-body calculations are used to study the influence of strong sub-picosecond pulses on the carrier distributions and corresponding optical response in saturable absorbers used for mode-locking—semiconductor (quantum well) saturable absorber mirrors (SESAMs) and single layer graphene based saturable absorber mirrors (GSAMs). Unlike in GSAMs, the saturation fluence and recovery time in SESAMs show a strong spectral dependence. While the saturation fluence in the SESAM is minimal at the excitonic bandgap, the optimal recovery time and least pulse distortion due to group delay dispersion are found for excitation higher in the first subband. For excitation near the SESAM bandgap, the saturation fluence is about one tenth of that in the GSAM. At energies above the bandgap, the fluences in both systems become similar. A strong dependence of the saturation fluence on the pulse width in both systems is caused by carrier relaxation during the pulse. The recovery time in graphene is found to be about two to four times faster than that in the SESAMs. The occurrence of negative differential transmission in graphene is shown to be caused by dopant related carriers. In SESAMs, a negative differential transmission is found when exciting below the excitonic resonance where excitation induced dephasing leads to an enhancement of the absorption. Comparisons of the simulation data to the experiment show a very good quantitative agreement.

  17. RF slice profile effects in magnetic resonance fingerprinting.

    Science.gov (United States)

    Hong, Taehwa; Han, Dongyeob; Kim, Min-Oh; Kim, Dong-Hyun

    2017-09-01

    The radio frequency (RF) slice profile effects on T1 and T2 estimation in magnetic resonance fingerprinting (MRF) are investigated with respect to time-bandwidth product (TBW), flip angle (FA) level and field inhomogeneities. Signal evolutions are generated incorporating the non-ideal slice selective excitation process using Bloch simulation and matched to the original dictionary with and without the non-ideal slice profile taken into account. For validation, phantom and in vivo experiments are performed at 3T. Both simulations and experiments results show that T1 and T2 error from non-ideal slice profile increases with increasing FA level, off-resonance, and low TBW values. Therefore, RF slice profile effects should be compensated for accurate determination of the MR parameters. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Saturated Zone In-Situ Testing

    International Nuclear Information System (INIS)

    Reimus, P. W.; Umari, M. J.

    2003-01-01

    The purpose of this scientific analysis is to document the results and interpretations of field experiments that have been conducted to test and validate conceptual flow and radionuclide transport models in the saturated zone (SZ) near Yucca Mountain. The test interpretations provide estimates of flow and transport parameters that are used in the development of parameter distributions for Total System Performance Assessment (TSPA) calculations. These parameter distributions are documented in the revisions to the SZ flow model report (BSC 2003 [ 162649]), the SZ transport model report (BSC 2003 [ 162419]), the SZ colloid transport report (BSC 2003 [162729]), and the SZ transport model abstraction report (BSC 2003 [1648701]). Specifically, this scientific analysis report provides the following information that contributes to the assessment of the capability of the SZ to serve as a barrier for waste isolation for the Yucca Mountain repository system: (1) The bases for selection of conceptual flow and transport models in the saturated volcanics and the saturated alluvium located near Yucca Mountain. (2) Results and interpretations of hydraulic and tracer tests conducted in saturated fractured volcanics at the C-wells complex near Yucca Mountain. The test interpretations include estimates of hydraulic conductivities, anisotropy in hydraulic conductivity, storativities, total porosities, effective porosities, longitudinal dispersivities, matrix diffusion mass transfer coefficients, matrix diffusion coefficients, fracture apertures, and colloid transport parameters. (3) Results and interpretations of hydraulic and tracer tests conducted in saturated alluvium at the Alluvium Testing Complex (ATC), which is located at the southwestern corner of the Nevada Test Site (NTS). The test interpretations include estimates of hydraulic conductivities, storativities, total porosities, effective porosities, longitudinal dispersivities, matrix diffusion mass transfer coefficients, and

  19. Saturated Zone In-Situ Testing

    Energy Technology Data Exchange (ETDEWEB)

    P. W. Reimus; M. J. Umari

    2003-12-23

    The purpose of this scientific analysis is to document the results and interpretations of field experiments that have been conducted to test and validate conceptual flow and radionuclide transport models in the saturated zone (SZ) near Yucca Mountain. The test interpretations provide estimates of flow and transport parameters that are used in the development of parameter distributions for Total System Performance Assessment (TSPA) calculations. These parameter distributions are documented in the revisions to the SZ flow model report (BSC 2003 [ 162649]), the SZ transport model report (BSC 2003 [ 162419]), the SZ colloid transport report (BSC 2003 [162729]), and the SZ transport model abstraction report (BSC 2003 [1648701]). Specifically, this scientific analysis report provides the following information that contributes to the assessment of the capability of the SZ to serve as a barrier for waste isolation for the Yucca Mountain repository system: (1) The bases for selection of conceptual flow and transport models in the saturated volcanics and the saturated alluvium located near Yucca Mountain. (2) Results and interpretations of hydraulic and tracer tests conducted in saturated fractured volcanics at the C-wells complex near Yucca Mountain. The test interpretations include estimates of hydraulic conductivities, anisotropy in hydraulic conductivity, storativities, total porosities, effective porosities, longitudinal dispersivities, matrix diffusion mass transfer coefficients, matrix diffusion coefficients, fracture apertures, and colloid transport parameters. (3) Results and interpretations of hydraulic and tracer tests conducted in saturated alluvium at the Alluvium Testing Complex (ATC), which is located at the southwestern corner of the Nevada Test Site (NTS). The test interpretations include estimates of hydraulic conductivities, storativities, total porosities, effective porosities, longitudinal dispersivities, matrix diffusion mass transfer coefficients, and

  20. Hybrid Magnetics and Power Applications

    DEFF Research Database (Denmark)

    Mo, Wai Keung; Paasch, Kasper

    2017-01-01

    A hybrid magnetic approach, merging two different magnetic core properites such as ferrite and iron powder cores, is an effective solution for power converter applications. It can offer similar magnetic properties to that of magnetic powder cores but showing less copper loss than powder cores....... In order to prevent ferrite core saturation, placing an effective air gap within the ferrite core is a key method to obtain optimum hybrid magnetic performance. Furthermore, a relatively large inductance at low loading current is an excellent way to minimze power loss in order to achieve high efficiency...

  1. Space Charge Saturated Sheath Regime and Electron Temperature Saturation in Hall Thrusters

    International Nuclear Information System (INIS)

    Raitses, Y.; Staack, D.; Smirnov, A.; Fisch, N.J.

    2005-01-01

    Secondary electron emission in Hall thrusters is predicted to lead to space charge saturated wall sheaths resulting in enhanced power losses in the thruster channel. Analysis of experimentally obtained electron-wall collision frequency suggests that the electron temperature saturation, which occurs at high discharge voltages, appears to be caused by a decrease of the Joule heating rather than by the enhancement of the electron energy loss at the walls due to a strong secondary electron emission

  2. Comparison of pulseoximetry oxygen saturation and arterial oxygen saturation in open heart intensive care unit

    Directory of Open Access Journals (Sweden)

    Alireza Mahoori

    2013-08-01

    Full Text Available Background: Pulseoximetry is widely used in the critical care setting, currently used to guide therapeutic interventions. Few studies have evaluated the accuracy of SPO2 (puls-eoximetry oxygen saturation in intensive care unit after cardiac surgery. Our objective was to compare pulseoximetry with arterial oxygen saturation (SaO2 during clinical routine in such patients, and to examine the effect of mild acidosis on this relationship.Methods: In an observational prospective study 80 patients were evaluated in intensive care unit after cardiac surgery. SPO2 was recorded and compared with SaO2 obtained by blood gas analysis. One or serial arterial blood gas analyses (ABGs were performed via a radial artery line while a reliable pulseoximeter signal was present. One hundred thirty seven samples were collected and for each blood gas analyses, SaO2 and SPO2 we recorded.Results: O2 saturation as a marker of peripheral perfusion was measured by Pulseoxim-etry (SPO2. The mean difference between arterial oxygen saturation and pulseoximetry oxygen saturation was 0.12%±1.6%. A total of 137 paired readings demonstrated good correlation (r=0.754; P<0.0001 between changes in SPO2 and those in SaO2 in samples with normal hemoglobin. Also in forty seven samples with mild acidosis, paired readings demonstrated good correlation (r=0.799; P<0.0001 and the mean difference between SaO2 and SPO2 was 0.05%±1.5%.Conclusion: Data showed that in patients with stable hemodynamic and good signal quality, changes in pulseoximetry oxygen saturation reliably predict equivalent changes in arterial oxygen saturation. Mild acidosis doesn’t alter the relation between SPO2 and SaO2 to any clinically important extent. In conclusion, the pulse oximeter is useful to monitor oxygen saturation in patients with stable hemodynamic.

  3. Scaling of saturation amplitudes in baroclinic instability

    International Nuclear Information System (INIS)

    Shepherd, T.G.

    1994-01-01

    By using finite-amplitude conservation laws for pseudomomentum and pseudoenergy, rigorous upper bounds have been derived on the saturation amplitudes in baroclinic instability for layered and continuously-stratified quasi-geostrophic models. Bounds have been obtained for both the eddy energy and the eddy potential enstrophy. The bounds apply to conservative (inviscid, unforced) flow, as well as to forced-dissipative flow when the dissipation is proportional to the potential vorticity. This approach provides an efficient way of extracting an analytical estimate of the dynamical scalings of the saturation amplitudes in terms of crucial non-dimensional parameters. A possible use is in constructing eddy parameterization schemes for zonally-averaged climate models. The scaling dependences are summarized, and compared with those derived from weakly-nonlinear theory and from baroclinic-adjustment estimates

  4. Effective stress principle for partially saturated media

    International Nuclear Information System (INIS)

    McTigue, D.F.; Wilson, R.K.; Nunziato, J.W.

    1984-04-01

    In support of the Nevada Nuclear Waste Storage Investigation (NNWSI) Project, we have undertaken a fundamental study of water migration in partially saturated media. One aspect of that study, on which we report here, has been to use the continuum theory of mixtures to extend the classical notion of effective stress to partially saturated media. Our analysis recovers previously proposed phenomenological representations for the effective stress in terms of the capillary pressure. The theory is illustrated by specializing to the case of linear poroelasticity, for which we calculate the deformation due to the fluid pressure in a static capillary fringe. We then examine the transient consolidation associated with liquid flow induced by an applied surface load. Settlement accompanies this flow as the liquid is redistributed by a nonlinear diffusion process. For material properties characteristic of tuff from the Nevada Test Site, these effects are found to be vanishingly small. 14 references, 7 figures, 1 table

  5. The danish tax on saturated fat

    DEFF Research Database (Denmark)

    Jensen, Jørgen Dejgård; Smed, Sinne

    Denmark introduced a new tax on saturated fat in food products with effect from October 2011. The objective of this paper is to make an effect assessment of this tax for some of the product categories most significantly affected by the new tax, namely fats such as butter, butter-blends, margarine...... on saturated fat in food products has had some effects on the market for the considered products, in that the level of consumption of fats dropped by 10 – 20%. Furthermore, the analysis points at shifts in demand from high-price supermarkets towards low-price discount stores – a shift that seems to have been...... utilized by discount chains to raise the prices of butter and margarine by more than the pure tax increase. Due to the relatively short data period with the tax being active, interpretation of these findings from a long-run perspective should be done with considerable care. It is thus recommended to repeat...

  6. Stabilization of Neutral Systems with Saturating Actuators

    Directory of Open Access Journals (Sweden)

    F. El Haoussi

    2012-01-01

    to determine stabilizing state-feedback controllers with large domain of attraction, expressed as linear matrix inequalities, readily implementable using available numerical tools and with tuning parameters that make possible to select the most adequate solution. These conditions are derived by using a Lyapunov-Krasovskii functional on the vertices of the polytopic description of the actuator saturations. Numerical examples demonstrate the effectiveness of the proposed technique.

  7. Gluon saturation beyond (naive) leading logs

    Energy Technology Data Exchange (ETDEWEB)

    Beuf, Guillaume

    2014-12-15

    An improved version of the Balitsky–Kovchegov equation is presented, with a consistent treatment of kinematics. That improvement allows to resum the most severe of the large higher order corrections which plague the conventional versions of high-energy evolution equations, with approximate kinematics. This result represents a further step towards having high-energy QCD scattering processes under control beyond strict Leading Logarithmic accuracy and with gluon saturation effects.

  8. Magnetically responsive enzyme powders

    Energy Technology Data Exchange (ETDEWEB)

    Pospiskova, Kristyna, E-mail: kristyna.pospiskova@upol.cz [Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Safarik, Ivo, E-mail: ivosaf@yahoo.com [Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Department of Nanobiotechnology, Institute of Nanobiology and Structural Biology of GCRC, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic)

    2015-04-15

    Powdered enzymes were transformed into their insoluble magnetic derivatives retaining their catalytic activity. Enzyme powders (e.g., trypsin and lipase) were suspended in various liquid media not allowing their solubilization (e.g., saturated ammonium sulfate and highly concentrated polyethylene glycol solutions, ethanol, methanol, 2-propanol) and subsequently cross-linked with glutaraldehyde. Magnetic modification was successfully performed at low temperature in a freezer (−20 °C) using magnetic iron oxides nano- and microparticles prepared by microwave-assisted synthesis from ferrous sulfate. Magnetized cross-linked enzyme powders were stable at least for two months in water suspension without leakage of fixed magnetic particles. Operational stability of magnetically responsive enzymes during eight repeated reaction cycles was generally without loss of enzyme activity. Separation of magnetically modified cross-linked powdered enzymes from reaction mixtures was significantly simplified due to their magnetic properties. - Highlights: • Cross-linked enzyme powders were prepared in various liquid media. • Insoluble enzymes were magnetized using iron oxides particles. • Magnetic iron oxides particles were prepared by microwave-assisted synthesis. • Magnetic modification was performed under low (freezing) temperature. • Cross-linked powdered trypsin and lipase can be used repeatedly for reaction.

  9. THE SATURATION OF SASI BY PARASITIC INSTABILITIES

    International Nuclear Information System (INIS)

    Guilet, Jerome; Sato, Jun'ichi; Foglizzo, Thierry

    2010-01-01

    The standing accretion shock instability (SASI) is commonly believed to be responsible for large amplitude dipolar oscillations of the stalled shock during core collapse, potentially leading to an asymmetric supernovae explosion. The degree of asymmetry depends on the amplitude of SASI, but the nonlinear saturation mechanism has never been elucidated. We investigate the role of parasitic instabilities as a possible cause of nonlinear SASI saturation. As the shock oscillations create both vorticity and entropy gradients, we show that both Kelvin-Helmholtz and Rayleigh-Taylor types of instabilities are able to grow on a SASI mode if its amplitude is large enough. We obtain simple estimates of their growth rates, taking into account the effects of advection and entropy stratification. In the context of the advective-acoustic cycle, we use numerical simulations to demonstrate how the acoustic feedback can be decreased if a parasitic instability distorts the advected structure. The amplitude of the shock deformation is estimated analytically in this scenario. When applied to the set up of Fernandez and Thompson, this saturation mechanism is able to explain the dramatic decrease of the SASI power when both the nuclear dissociation energy and the cooling rate are varied. Our results open new perspectives for anticipating the effect, on the SASI amplitude, of the physical ingredients involved in the modeling of the collapsing star.

  10. Optimal oxygen saturation in premature infants

    Directory of Open Access Journals (Sweden)

    Meayoung Chang

    2011-09-01

    Full Text Available There is a delicate balance between too little and too much supplemental oxygen exposure in premature infants. Since underuse and overuse of supplemental oxygen can harm premature infants, oxygen saturation levels must be monitored and kept at less than 95% to prevent reactive oxygen species-related diseases, such as retinopathy of prematurity and bronchopulmonary dysplasia. At the same time, desaturation below 80 to 85% must be avoided to prevent adverse consequences, such as cerebral palsy. It is still unclear what range of oxygen saturation is appropriate for premature infants; however, until the results of further studies are available, a reasonable target for pulse oxygen saturation (SpO2 is 90 to 93% with an intermittent review of the correlation between SpO2 and the partial pressure of arterial oxygen tension (PaO2. Because optimal oxygenation depends on individuals at the bedside making ongoing adjustments, each unit must define an optimal target range and set alarm limits according to their own equipment or conditions. All staff must be aware of these values and adjust the concentration of supplemental oxygen frequently.

  11. Saturation and nucleation in hot nuclear systems

    International Nuclear Information System (INIS)

    Deangelis, A.R.

    1990-07-01

    We investigate nuclear fragmentation in a supersaturated system using classical nucleation theory. This allows us to go outside the normally applied constraint of chemical equilibrium. The system is governed by a virial equation of state, which we use to find an expression for the density as a function of pressure and temperature. The evolution of the system is discussed in terms of the phase diagram. Corrections are included to account for the droplet surface and all charges contained in the system. Using this model we investigate and discuss the effects of temperature and saturation, and compare the results to those of other models of fragmentation. We also discuss the limiting temperatures of the system for the cases with and without chemical equilibrium. We find that large nuclei will be formed in saturated systems, even above the limiting temperature as previously defined. We also find that saturation and temperature dominate surface and Coulomb effects. The effects are quite large, thus even a qualitative inspection of the yields may give an indication of the conditions during fragmentation

  12. Multipactor saturation in parallel-plate waveguides

    International Nuclear Information System (INIS)

    Sorolla, E.; Mattes, M.

    2012-01-01

    The saturation stage of a multipactor discharge is considered of interest, since it can guide towards a criterion to assess the multipactor onset. The electron cloud under multipactor regime within a parallel-plate waveguide is modeled by a thin continuous distribution of charge and the equations of motion are calculated taking into account the space charge effects. The saturation is identified by the interaction of the electron cloud with its image charge. The stability of the electron population growth is analyzed and two mechanisms of saturation to explain the steady-state multipactor for voltages near above the threshold onset are identified. The impact energy in the collision against the metal plates decreases during the electron population growth due to the attraction of the electron sheet on the image through the initial plate. When this growth remains stable till the impact energy reaches the first cross-over point, the electron surface density tends to a constant value. When the stability is broken before reaching the first cross-over point the surface charge density oscillates chaotically bounded within a certain range. In this case, an expression to calculate the maximum electron surface charge density is found whose predictions agree with the simulations when the voltage is not too high.

  13. Mass transfer in water-saturated concretes

    International Nuclear Information System (INIS)

    Atkinson, A.; Claisse, P.A.; Harris, A.W.; Nickerson, A.K.

    1990-01-01

    Cements and concretes are often considered as components of barriers for the containment of radioactive waste. The performance of such materials as mainly physical barriers to the transport of dissolved radionuclides depends on the mass transfer characteristics of the material. In particular the diffusion and sorption behavior of the radionuclides and the water permeability are important. These parameters also influence how the chemistry of the concrete is imposed on the repository. In addition, the transport of gas through concrete controls the way in which gases escape from the repository. Diffusion and gas transport have been measured in a variety of cementitious materials, covering both structural concretes and cementitious backfills; all possible repository construction materials. Measurements have been made using aqueous iodide, strontium and caesium ions and tritiated water as diffusants. The results show that the diffusion of tritiated water is more rapid than that of other species, whilst the transport of strontium and caesium is hindered by sorption; particularly in materials containing blast furnace slag. The transport of gas in these materials has been found to be very sensitive to the degree of water saturation and is extremely low in fully saturated structural concretes. Cementitious backfills have, nevertheless, been identified that have appreciable gas transport even when almost water saturated. The consequences of the results for the performance of cementitious barriers are discussed

  14. The statistic-thermodynamically calculations of magnetic thermodynamically functions for nuclear magnetic moments

    International Nuclear Information System (INIS)

    Zhu Zhenghe; Luo Deli; Feng Kaiming

    2013-01-01

    The present work is to calculate the magnetic thermodynamically functions, i.e. energy, the intensity of magnetization, enthalpy, entropy and Gibbs function for nuclear magnetic moments of T, D and neutron n at 2 T and 1, 50, 100 and 150 K from partition functions. It is shown that magnetic saturation of thermonuclear plasma does not easily occur for nuclear magneton is only of 10 -3 of Bohr magneton. The work done by magnetic field is considerable. (authors)

  15. Fat-saturated diffusion-weighted imaging with three-dimensional MP-RAGE sequence

    International Nuclear Information System (INIS)

    Numano, Tomokazu; Homma, Kazuhiro; Takahashi, Nobuyuki; Hirose, Takeshi

    2005-01-01

    Image misrepresentation due to chemical shifts can create image artifacts on MR images. Distinguishing the organization and affected area can be difficult due to the chemical shift artifacts. Chemical shift selective (CHESS) is a method of decreasing chemical shift artifacts. In this study we have developed a new sequence for fat-saturated three-dimensional diffusion weighted MR imaging. This imaging was done during in vivo studies using an animal experiment MR imaging system at 2.0 T. In this sequence a preparation phase with a ''CHESS-90 deg RF-Motion Proving Gradient (MPG-180 deg RF-MPG-90 deg RF pulse train) was used to sensitize the magnetization to fat-saturated diffusion. Centric k-space acquisition order is necessary to minimize saturation effects from tissues with short relaxation times. From experimental results obtained with a phantom, the effect of the diffusion weighting and the effect of the fat-saturation were confirmed. From rat experimental results, fat-saturated diffusion weighted image data (0.55 x 0.55 x 0.55 mm 3 : voxel size) were obtained. This sequence was useful for in vivo imaging. (author)

  16. Mechanics of magnetic fluid column in strong magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Polunin, V.M.; Ryapolov, P.A., E-mail: r-piter@yandex.ru; Platonov, V.B.

    2017-06-01

    Elastic-and magnetic properties of magnetic fluid confined by ponderomotive force in a tube fixed in horizontal position are considered. The system is placed in a strong magnetic field under the influence of external static and dynamic perturbations. An experimental setup has been developed. A theoretical basis of the processes of magnetic colloid elastic deformation has been proposed. The values of the static ponderomotive elasticity coefficient and the elasticity coefficient under dynamic action are experimentally determined. The calculations of the saturation magnetization for two magnetic fluid samples, carried out according to the equation containing the dynamic elasticity coefficient, are in good agreement with the experimental magnetization curve. The described method is of interest when studying magnetophoresis and aggregation of nanoparticles in magnetic colloids.

  17. Bat head contains soft magnetic particles: evidence from magnetism.

    Science.gov (United States)

    Tian, Lanxiang; Lin, Wei; Zhang, Shuyi; Pan, Yongxin

    2010-10-01

    Recent behavioral observations have indicated that bats can sense the Earth's magnetic field. To unravel the magnetoreception mechanism, the present study has utilized magnetic measurements on three migratory species (Miniopterus fuliginosus, Chaerephon plicata, and Nyctalus plancyi) and three non-migratory species (Hipposideros armiger, Myotis ricketti, and Rhinolophus ferrumequinum). Room temperature isothermal remanent magnetization acquisition and alternating-field demagnetization showed that the bats' heads contain soft magnetic particles. Statistical analyses indicated that the saturation isothermal remanent magnetization of brains (SIRM(1T_brain)) of migratory species is higher than those of non-migratory species. Furthermore, the SIRM(1T_brain) of migratory bats is greater than their SIRM(1T_skull). Low-temperature magnetic measurements suggested that the magnetic particles are likely magnetite (Fe3O4). This new evidence supports the assumption that some bats use magnetite particles for sensing and orientation in the Earth's magnetic field.

  18. The Characterization of the Magnetic Properties of Soft Magnetic Materials

    DEFF Research Database (Denmark)

    Larsen, Raino Michael

    1996-01-01

    The hysteresis curve and magnetic properties such as permeability, saturation induction, residual induction, coercive force and hysteresis losses are presented. The design and construction of equipment making it possible to measure true DC-values as well as AC-properties of toroid rings and cylin......The hysteresis curve and magnetic properties such as permeability, saturation induction, residual induction, coercive force and hysteresis losses are presented. The design and construction of equipment making it possible to measure true DC-values as well as AC-properties of toroid rings...

  19. Superconducting Accelerator Magnets

    CERN Document Server

    Mess, K H; Wolff, S

    1996-01-01

    The main topic of the book are the superconducting dipole and quadrupole magnets needed in high-energy accelerators and storage rings for protons, antiprotons or heavy ions. The basic principles of low-temperature superconductivity are outlined with special emphasis on the effects which are relevant for accelerator magnets. Properties and fabrication methods of practical superconductors are described. Analytical methods for field calculation and multipole expansion are presented for coils without and with iron yoke. The effect of yoke saturation and geometric distortions on field quality is studied. Persistent magnetization currents in the superconductor and eddy currents the copper part of the cable are analyzed in detail and their influence on field quality and magnet performance is investigated. Superconductor stability, quench origins and propagation and magnet protection are addressed. Some important concepts of accelerator physics are introduced which are needed to appreciate the demanding requirements ...

  20. Model for the saturation of the hydromagnetic Rayleigh--Taylor instability

    International Nuclear Information System (INIS)

    Roderick, N.F.; Hussey, T.W.

    1984-01-01

    The saturation of the hydromagnetic Rayleigh--Taylor instability is caused by the reduction of driving current in the bubble region between the spikes formed as the instability develops. For short wavelengths linear magnetic field diffusion provides the necessary smoothing of the magnetic field to reduce the driving force. For wavelengths longer than the magnetic field diffusion length, the current is shorted through material which expands into the bubble region. This initially low density accumulates in the bubble and eventually provides a source of sufficiently high conductivity plasma which reduces the magnetic field penetration to the front of the bubble. Simple analytic models have been developed to verify and and quantify these predictions. These models have been compared with two-dimensional magnetohydrodynamic calculations for imploding plasma shells and give good agreement with these more detailed simulations

  1. Soil aquifer treatment of artificial wastewater under saturated conditions

    KAUST Repository

    Essandoh, H. M K; Tizaoui, Chedly; Mohamed, Mostafa H A; Amy, Gary L.; Brdjanovic, Damir

    2011-01-01

    A 2000 mm long saturated laboratory soil column was used to simulate soil aquifer treatment under saturated conditions to assess the removal of chemical and biochemical oxygen demand (COD and BOD), dissolved organic carbon (DOC), nitrogen

  2. Calcium phosphate saturation in the western Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Naik, S.; Reddy, C.V.G.

    Temperature, inorganic phosphate concentration and pH seem to be the major factors influencing the degree of saturation of calcium phosphate in sea water. Two water regions can be demarcated in the study area based on the saturation patterns...

  3. Automated agitation management accounting for saturation dynamics.

    Science.gov (United States)

    Rudge, A D; Chase, J G; Shaw, G M; Lee, D

    2004-01-01

    Agitation-sedation cycling in critically ill is damaging to patient health and increases length of and cost. A physiologically representative model of the agitation-sedation system is used as a platform to evaluate feedback controllers offering improved agitation management. A heavy-derivative controller with upper and infusion rate bounds maintains minimum plasma concentrations through a low constant infusion, and minimizes outbursts of agitation through strong, timely boluses. controller provides improved agitation management using from 37 critically ill patients, given the saturation of effect at high concentration. Approval was obtained the Canterbury Ethics Board for this research.

  4. Modelling contaminant transport in saturated aquifers

    International Nuclear Information System (INIS)

    Lakshminarayana, V.; Nayak, T.R.

    1990-01-01

    With the increase in population and industrialization the problem of pollution of groundwater has become critical. The present study deals with modelling of pollutant transport through saturated aquifers. Using this model it is possible to predict the concentration distribution, spatial as well as temporal, in the aquifer. The paper also deals with one of the methods of controlling the pollutant movement, namely by pumping wells. A simulation model is developed to determine the number, location and rate of pumping of a number of wells near the source of pollution so that the concentration is within acceptable limits at the point of interest. (Author) (18 refs., 14 figs., tab.)

  5. Elevated transferrin saturation and risk of diabetes

    DEFF Research Database (Denmark)

    Ellervik, Christina; Mandrup-Poulsen, Thomas; Andersen, Henrik Ullits

    2011-01-01

    OBJECTIVE We tested the hypothesis that elevated transferrin saturation is associated with an increased risk of any form of diabetes, as well as type 1 or type 2 diabetes separately. RESEARCH DESIGN AND METHODS We used two general population studies, The Copenhagen City Heart Study (CCHS, N = 9......,121) and The Copenhagen General Population Study (CGPS, N = 24,195), as well as a 1:1 age- and sex-matched population-based case-control study with 6,129 patients with diabetes from the Steno Diabetes Centre and 6,129 control subjects, totaling 8,535 patients with diabetes and 37,039 control subjects. RESULTS...

  6. The Danish tax on saturated fat

    DEFF Research Database (Denmark)

    Vallgårda, Signild; Holm, Lotte; Jensen, Jørgen Dejgård

    2015-01-01

    arguments and themes involved in the debates surrounding the introduction and the repeal. SUBJECTS/METHODS: An analysis of parliamentary debates, expert reports and media coverage; key informant interviews; and a review of studies about the effects of the tax on consumer behaviour. RESULTS: A tax......BACKGROUND/OBJECTIVES: Health promoters have repeatedly proposed using economic policy tools, taxes and subsidies, as a means of changing consumer behaviour. As the first country in the world, Denmark introduced a tax on saturated fat in 2011. It was repealed in 2012. In this paper, we present...... indicates that the tax was effective in changing consumer behaviour....

  7. Regulation of fields excited by permanent magnets

    International Nuclear Information System (INIS)

    Savchenko, I.S.

    1989-01-01

    Two methods of fast regulation of fields excited by permanent magnets in salient-pole electron-optical lenses are described: 1)the hybrid method realized using the additional electromagnet introduced to a magnetic chain sequentially its field being composed or substracted with magnetosolid exciter field; 2)the method with saturation of a part of a magnetic circuit, with saturation being achievable at the begining or in the end of a regulation cycle. In the second method it is proposed to direct orthogonally the main flux excited by permanent magnets and the flux in the saturated part of the magnetic circuit excited using an electromagnet. It is shown that the second method allows one to reduce the required ampere-coils by more than an order as compared to the first method at one and the same regulation range and other equal conditions. The frequency of field regulation in the experimental mock-up was 10 kHz. 3 refs.; 2 figs

  8. Cage-rotor induction motor inter-turn short circuit fault detection with and without saturation effect by MEC model.

    Science.gov (United States)

    Naderi, Peyman

    2016-09-01

    The inter-turn short fault for the Cage-Rotor-Induction-Machine (CRIM) is studied in this paper and its local saturation is taken into account. However, in order to observe the exact behavior of machine, the Magnetic-Equivalent-Circuit (MEC) and nonlinear B-H curve are proposed to provide an insight into the machine model and saturation effect respectively. The electrical machines are generally operated near to their saturation zone due to some design necessities. Hence, when the machine is exposed to a fault such as short circuit or eccentricities, it is operated within its saturation zone and thus, time and space harmonics are integrated and as a result, current and torque harmonics are generated which the phenomenon cannot be explored when saturation is dismissed. Nonetheless, inter-turn short circuit may lead to local saturation and this occurrence is studied in this paper using MEC model. In order to achieve the mentioned objectives, two and also four-pole machines are modeled as two samples and the machines performances are analyzed in healthy and faulty cases with and without saturation effect. A novel strategy is proposed to precisely detect inter-turn short circuit fault according to the stator׳s lines current signatures and the accuracy of the proposed method is verified by experimental results. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  9. A demonstration experiment for studying the properties of saturated vapor

    Science.gov (United States)

    Grebenev, Igor V.; Lebedeva, Olga V.; Polushkina, Svetlana V.

    2017-11-01

    The paper proposes an important demonstration experiment that can be used at secondary schools in physics. The described experiment helps students learn the main concepts of the topic ‘saturated vapor’, namely, evaporation, condensation, dynamic equilibrium, saturation vapor, partial pressure, and the dependence of saturated vapor pressure on temperature.

  10. In vivo detection of hemoglobin oxygen saturation and carboxyhemoglobin saturation with multiwavelength photoacoustic microscopy.

    Science.gov (United States)

    Chen, Zhongjiang; Yang, Sihua; Xing, Da

    2012-08-15

    A method for noninvasively detecting hemoglobin oxygen saturation (SO2) and carboxyhemoglobin saturation (SCO) in subcutaneous microvasculature with multiwavelength photoacoustic microscopy is presented. Blood samples mixed with different concentrations of carboxyhemoglobin were used to test the feasibility and accuracy of photoacoustic microscopy compared with the blood-gas analyzer. Moreover, fixed-point detection of SO2 and SCO in mouse ear was obtained, and the changes from normoxia to carbon monoxide hypoxia were dynamically monitored in vivo. Experimental results demonstrate that multiwavelength photoacoustic microscopy can detect SO2 and SCO, which has future potential clinical applications.

  11. Particle Correlations in Saturated QCD Matter

    CERN Document Server

    Baier, R; Nardi, M; Wiedemann, Urs Achim; Baier, Rudolf; Kovner, Alex; Nardi, Marzia; Wiedemann, Urs Achim

    2005-01-01

    We study quantitatively angular correlations in the two-particle spectrum produced by an energetic probe scattering off a dense hadronic target with sizeable saturation momentum. To this end, two parton inclusive cross sections for arbitrary projectiles with small color charge density are derived in the eikonal formalism. Our results are the following: For large momenta of the observed particles, the perturbative limit with characteristic back-to-back correlation is recovered. As the trigger momenta get closer to the saturation scale Q_s, the angular distribution broadens. When the momenta are significantly smaller than Q_s, the azimuthal distribution is broad but still peaked back-to-back. However, in a narrow momentum range (0.5 - 1.5) Q_s, we observe that the azimuthal correlation splits into a double peak with maxima displaced away from 180 degree. We argue that it is the soft multiple scattering physics that is responsible for the appearance of this shift in the angle of maximal correlation. We also poin...

  12. Facilitated transport near the carrier saturation limit

    Directory of Open Access Journals (Sweden)

    Anawat Sungpet

    2002-11-01

    Full Text Available Permeation of ethylbenzene, styrene and 1-hexene through perfluorosulfonate ionomer membranes was carried out with the feed concentrations ranging from 1 M to pure. On comparison, fluxes of ethylbenzene through the Ag+-form membrane were the lowest. Only a small increase in ethylbenzene flux was observed after the feed concentration exceeded 3 M, indicating the existence of carrier saturation. The increase in styrene flux was suppressed to some degree at high concentration driving forces. In contrast, 1-hexene flux was the highest and continued to increase even at very high feed concentrations. After the experiments with pure feeds, extraction of the solutes from the membranes revealed that 62.5% of Ag+ ions reacted with 1-hexene as against 40.6% for styrene and 28.9% for ethylbenzene. Equilibrium constants, determined by distribution method, of 1-hexene, styrene and ethylbenzene were 129, 2.2 and 0.7 M-1 respectively, which suggested that stability of the complex was a key factor in the carrier saturation phenomenon.

  13. Salt-saturated concrete strength and permeability

    International Nuclear Information System (INIS)

    Pfeifle, T.W.; Hansen, F.D.; Knowles, M.K.

    1996-01-01

    Laboratory-scale experiments applicable to the use of salt-saturated concrete as a seal material for a transuranic waste repository have been completed. Nitrogen gas permeability measurements were made using a flexible-wall permeameter, a confining pressure of 1 MPa, and gas pressure gradients ranging from 0.3 MPa to 0.75 MPa. Results show that salt-saturated concrete has very low intrinsic permeability with values ranging from 9.4 x 10 -22 m 2 to 9.7 x 10 -17 m 2 . Strength and deformation characteristics were investigated under conditions of triaxial compression with confining pressures ranging from 0 to 15 MPa using either axial strain-rate or axial stress-rate control and show that the failure strength of concrete increases with confining pressure which can be adequately described through pressure-sensitive failure criteria. Axial, radial, and volumetric strains were also measured during each test and these data were used to determine elastic properties. Experimental results are applicable in the design and analysis of scale-related functions and apply to other concrete structures subjected to compressive loadings such as dams and prestressed structural members

  14. Characteristics of magnetic switch used as main switch of solid-state accelerator

    International Nuclear Information System (INIS)

    Li Song; Qian Baoliang; Yang Hanwu; Meng Zhipeng; Yang Shi

    2012-01-01

    In order to improve the performance of solid-state accelerator, the characteristics of magnetic switch used as the main switch of the accelerator have been investigated. The volume of magnetic core, the loss, and saturated inductance of the magnetic switch have been derived. The results show that the spacing factor of the magnetic switch reaches the peak when the height of the magnetic materials is 0.05 m for selected magnetic cores. The saturated inductance of the windings changes slowly when the average magnetic path length of the core is greater than 1 m. The physical process of saturation in the cores was analyzed by using saturation-wave theory. The rise-time factor of the output pulse was derived. The thickness, resistivity and magnetic path length difference of the magnetic core are shown to be key parameters affecting the rise-time factor. (authors)

  15. SITE-SCALE SATURATED ZONE TRANSPORT

    International Nuclear Information System (INIS)

    S. KELLER

    2004-01-01

    This work provides a site-scale transport model for calculating radionuclide transport in the saturated zone (SZ) at Yucca Mountain, for use in the abstractions model in support of ''Total System Performance Assessment for License Application'' (TSPA-LA). The purpose of this model report is to provide documentation for the components of the site-scale SZ transport model in accordance with administrative procedure AP-SIII.10Q, Models. The initial documentation of this model report was conducted under the ''Technical Work Plan For: Saturated Zone Flow and Transport Modeling and Testing'' (BSC 2003 [DIRS 163965]). The model report has been revised in accordance with the ''Technical Work Plan For: Natural System--Saturated Zone Analysis and Model Report Integration'', Section 2.1.1.4 (BSC 2004 [DIRS 171421]) to incorporate Regulatory Integration Team comments. All activities listed in the technical work plan that are appropriate to the transport model are documented in this report and are described in Section 2.1.1.4 (BSC 2004 [DIRS 171421]). This report documents: (1) the advection-dispersion transport model including matrix diffusion (Sections 6.3 and 6.4); (2) a description and validation of the transport model (Sections 6.3 and 7); (3) the numerical methods for simulating radionuclide transport (Section 6.4); (4) the parameters (sorption coefficient, Kd ) and their uncertainty distributions used for modeling radionuclide sorption (Appendices A and C); (5) the parameters used for modeling colloid-facilitated radionuclide transport (Table 4-1, Section 6.4.2.6, and Appendix B); and (6) alternative conceptual models and their dispositions (Section 6.6). The intended use of this model is to simulate transport in saturated fractured porous rock (double porosity) and alluvium. The particle-tracking method of simulating radionuclide transport is incorporated in the finite-volume heat and mass transfer numerical analysis (FEHM) computer code, (FEHM V2.20, STN: 10086

  16. Magnetic properties of magnetic glass-like carbon prepared from furan resin alloyed with magnetic fluid

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Kazumasa, E-mail: naka@sss.fukushima-u.ac.jp [Materials Science Area, Graduate School of Symbiotic Systems Science and Technology, Fukushima University, 1 Kanayagawa, Fukushima 960-1296 (Japan); Okuyama, Kyoko [Materials Science Area, Graduate School of Symbiotic Systems Science and Technology, Fukushima University, 1 Kanayagawa, Fukushima 960-1296 (Japan); Takase, Tsugiko [Institute of Environmental Radioactivity (IER), Fukushima University, 1 Kanayagawa, Fukushima 960-1296 (Japan)

    2017-03-01

    Magnetic glass-like carbons that were heat-treated at different temperatures or were filled with different magnetic nanoparticle contents were prepared from furan resin alloyed with magnetic fluid (MF) or Fe{sub 3}O{sub 4} powder in their liquid-phase states during mixing. Compared to the Fe{sub 3}O{sub 4} powder-alloyed carbon, the MF-alloyed carbon has highly dispersed the nanoparticles, and has the excellent saturation magnetization and coercivity. It is implied that saturation magnetizations are related to changes in the types of phases for the nanoparticles and the relative intensities of X-ray diffraction peaks for iron and iron-containing compounds in the carbons. Additionally, the coercivities are possibly affected by the size and crystallinity of the nanoparticles, the relative amounts of iron, and the existence of amorphous compounds on the carbon surfaces. - Highlights: • Magnetic glass-like carbons were prepared from furan resin alloyed with magnetic fluid. • The nanoparticles of MF-alloyed GLCs were highly dispersed. • MF-alloyed GLCs had excellent magnetic properties compared to powder-alloyed ones. • The magnetic properties changed with treatment temperature and nanoparticle content. • The changes in magnetic properties were investigated with XRD and FE-SEM.

  17. The Dependence of Water Permeability in Quartz Sand on Gas Hydrate Saturation in the Pore Space

    Science.gov (United States)

    Kossel, E.; Deusner, C.; Bigalke, N.; Haeckel, M.

    2018-02-01

    Transport of fluids in gas hydrate bearing sediments is largely defined by the reduction of the permeability due to gas hydrate crystals in the pore space. Although the exact knowledge of the permeability behavior as a function of gas hydrate saturation is of crucial importance, state-of-the-art simulation codes for gas production scenarios use theoretically derived permeability equations that are hardly backed by experimental data. The reason for the insufficient validation of the model equations is the difficulty to create gas hydrate bearing sediments that have undergone formation mechanisms equivalent to the natural process and that have well-defined gas hydrate saturations. We formed methane hydrates in quartz sand from a methane-saturated aqueous solution and used magnetic resonance imaging to obtain time-resolved, three-dimensional maps of the gas hydrate saturation distribution. These maps were fed into 3-D finite element method simulations of the water flow. In our simulations, we tested the five most well-known permeability equations. All of the suitable permeability equations include the term (1-SH)n, where SH is the gas hydrate saturation and n is a parameter that needs to be constrained. The most basic equation describing the permeability behavior of water flow through gas hydrate bearing sand is k = k0 (1-SH)n. In our experiments, n was determined to be 11.4 (±0.3). Results from this study can be directly applied to bulk flow analysis under the assumption of homogeneous gas hydrate saturation and can be further used to derive effective permeability models for heterogeneous gas hydrate distributions at different scales.

  18. Plasma current sustainment after iron core saturation in the STOR-M tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Mitarai, O., E-mail: omitarai@ktmail.tokai-u.jp [Kumamoto Liberal Arts Education Center, Tokai University, 9-1-1 Toroku, Higashi-ku, Kumamoto 862-8652 (Japan); Ding, Y.; Hubeny, M.; Lu, Y.; Onchi, T.; McColl, D.; Xiao, C.; Hirose, A. [Plasma Physics Laboratory, University of Saskatchewan, 116 Science Place, Saskatoon, SK S7N 5E2 (Canada)

    2014-10-15

    Highlights: • Plasma current can be started up by small iron core without central solenoid. • Iron core removes central solenoid. • Plasma current can be maintained after iron core saturation. • Hysteresis curve shows the partial core saturation. • Image field from iron core is estimated during discharge. • Spherical tokamak reactor without CS is proposed using the small iron core. - Abstract: We propose to use of a small iron core transformer to start up the plasma current in a spherical tokamak (ST) reactor without central solenoid (CS). Taking advantage of the high aspect ratio of the STOR-M iron core tokamak, we have demonstrated that the plasma current up to 10–15 kA can be started up using the outer Ohmic heating (OH) coils without CS, and that the plasma current can be maintained further by increasing the outer OH coil current during iron core saturation phase. When the magnetizing current reaches 1.2 kA and the iron core becomes saturated, the third capacitor bank connected to the outer OH coils is discharged to maintain the plasma current. The plasma current is slightly increased and maintained for additional 5 ms as expected from numerical calculations. Core saturation has been clearly observed on the hysteresis curve. This is the first experimental demonstration of the feasibility of slow transition from the iron core to air core transformer phase without CS. The results implies that a plasma current can be initiated by a small iron core and could be ramped up by additional heating and vertical field after iron core saturation in future STs without CS.

  19. Energy dependent saturable and reverse saturable absorption in cube-like polyaniline/polymethyl methacrylate film

    Energy Technology Data Exchange (ETDEWEB)

    Thekkayil, Remyamol [Department of Chemistry, Indian Institute of Space Science and Technology, Valiamala, Thiruvananthapuram 695 547 (India); Philip, Reji [Light and Matter Physics Group, Raman Research Institute, C.V. Raman Avenue, Bangalore 560 080 (India); Gopinath, Pramod [Department of Physics, Indian Institute of Space Science and Technology, Valiamala, Thiruvananthapuram 695 547 (India); John, Honey, E-mail: honey@iist.ac.in [Department of Chemistry, Indian Institute of Space Science and Technology, Valiamala, Thiruvananthapuram 695 547 (India)

    2014-08-01

    Solid films of cube-like polyaniline synthesized by inverse microemulsion polymerization method have been fabricated in a transparent PMMA host by an in situ free radical polymerization technique, and are characterized by spectroscopic and microscopic techniques. The nonlinear optical properties are studied by open aperture Z-scan technique employing 5 ns (532 nm) and 100 fs (800 nm) laser pulses. At the relatively lower laser pulse energy of 5 μJ, the film shows saturable absorption both in the nanosecond and femtosecond excitation domains. An interesting switchover from saturable absorption to reverse saturable absorption is observed at 532 nm when the energy of the nanosecond laser pulses is increased. The nonlinear absorption coefficient increases with increase in polyaniline concentration, with low optical limiting threshold, as required for a good optical limiter. - Highlights: • Synthesized cube-like polyaniline nanostructures. • Fabricated polyaniline/PMMA nanocomposite films. • At 5 μJ energy, saturable absorption is observed both at ns and fs regime. • Switchover from SA to RSA is observed as energy of laser beam increases. • Film (0.1 wt % polyaniline) shows high β{sub eff} (230 cm GW{sup −1}) and low limiting threshold at 150 μJ.

  20. Simulation of the saturation process of a radwaste storage cell

    International Nuclear Information System (INIS)

    Robbe, M.F.; Clouard, A.

    2001-01-01

    This paper presents a simulation of the saturation of the barrier and the plug of a storage cell by the surrounding host rock. Generally speaking, the unsaturated barrier and plug start saturating immediately in the vicinity of the quasi-saturated host rock. Then the saturation front propagates towards the canisters and the symmetry axis. Apart from the part in contact with the plug, the barrier is saturated at about 30 years. The part of the barrier near the plug is saturated around 80 years. If the top of the plug is saturated very soon, the part in the corner near the gallery and the symmetry axis is not completely saturated after 100 years. In the site, we observe a small desaturation during the first month, at the limit with the plug and the barrier, and especially in the corner limited by both FoCa clay pieces. This transient phenomenon may be assigned to the time difference between the immediate suction of water by the unsaturated materials and the delayed water flows coming from the saturated host rock to compensate the water suction. The purpose of this computation was at once to estimate the time necessary for the saturation of the clay layers surrounding the radwaste canisters and to evaluate the hydro-mechanical behaviour of the storage cell during the saturation process. Therefore a mechanical simulation was performed using the present hydraulic results to initiate the mechanical computation. (authors)

  1. Saturation of DNA repair in mammalian cells

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, F E; Setlow, R B

    1979-01-01

    Excision repair seems to reach a plateau in normal human cells at a 254 nm dose near 20 J/m/sup 2/. We measured excision repair in normal human fibroblasts up to 80 J/m/sup 2/. The four techniques used (unscheduled DNA synthesis, photolysis of BrdUrd incorporated during repair, loss of sites sensitive to a UV endonuclease from Micrococcus luteus, and loss of pyrimidine dimers from DNA) showed little difference between the two doses. Moreover, the loss of endonuclease sites in 24h following two 20 J/m/sup 2/ doses separated by 24h was similar to the loss observed following one dose. Hence, we concluded that the observed plateau in excision repair is real and does not represent some inhibitory process at high doses but a true saturation of one of the rate limiting steps in repair.

  2. The Danish tax on saturated fat

    DEFF Research Database (Denmark)

    Jensen, Jørgen Dejgård; Smed, Sinne

    2013-01-01

    and oils. This assessment is done by conducting an econometric analysis on weekly food purchase data from a large household panel dataset (GfK Consumer Tracking Scandinavia), spanning the period from January 2008 until July 2012.The econometric analysis suggest that the introduction of the tax on saturated...... and fats, a shift that seems to have been utilized by discount chains to raise the prices of butter and margarine by more than the pure tax increase. Due to the relatively short data period with the tax being active, interpretation of these findings from a long-run perspective should be done...... with considerable care. It is thus recommended to repeat – and broaden – the analysis at a later stage, when data are available for a longer period after the introduction of the fat tax....

  3. Relative Humidity in the Tropopause Saturation Layer

    Science.gov (United States)

    Selkirk, H. B.; Schoeberl, M. R.; Pfister, L.; Thornberry, T. D.; Bui, T. V.

    2017-12-01

    The tropical tropopause separates two very different atmospheric regimes: the stable lower stratosphere where the air is both extremely dry and nearly always so, and a transition layer in the uppermost tropical troposphere, where humidity on average increases rapidly downward but can undergo substantial temporal fluctuations. The processes that control the humidity in this layer below the tropopause include convective detrainment (which can result in either a net hydration or dehydration), slow ascent, wave motions and advection. Together these determine the humidity of the air that eventually passes through the tropopause and into the stratosphere, and we refer to this layer as the tropopause saturation layer or TSL. We know from in situ water vapor observations such as Ticosonde's 12-year balloonsonde record at Costa Rica that layers of supersaturation are frequently observed in the TSL. While their frequency is greatest during the local rainy season from June through October, supersaturation is also observed in the boreal winter dry season when deep convection is well south of Costa Rica. In other words, local convection is not a necessary condition for the presence of supersaturation. Furthermore, there are indications from airborne measurements during the recent POSIDON campaign at Guam that if anything deep convection tends to `reset' the TSL locally to a state of just-saturation. Conversely, it may be that layers of supersaturation are the result of slow ascent. To explore these ideas we take Ticosonde water vapor observations from the TSL, stratify them on the basis of relative humidity and report on the differences in the the history of upstream convective influence between supersaturated parcels and those that are not.

  4. Magnetic binary nanofillers

    International Nuclear Information System (INIS)

    Morales Mendoza, N.; Goyanes, S.; Chiliotte, C.; Bekeris, V.; Rubiolo, G.; Candal, R.

    2012-01-01

    Magnetic binary nanofillers containing multiwall carbon nanotubes (MWCNT) and hercynite were synthesized by Chemical Vapor Deposition (CVD) on Fe/AlOOH prepared by the sol-gel method. The catalyst precursor was fired at 450 °C, ground and sifted through different meshes. Two powders were obtained with different particle sizes: sample A (50-75 μm) and sample B (smaller than 50 μm). These powders are composed of iron oxide particles widely dispersed in the non-crystalline matrix of aluminum oxide and they are not ferromagnetic. After reduction process the powders are composed of α-Fe nanoparticles inside hercynite matrix. These nanofillers are composed of hercynite containing α-Fe nanoparticles and MWCNT. The binary magnetic nanofillers were slightly ferromagnetic. The saturation magnetization of the nanofillers depended on the powder particle size. The nanofiller obtained from powder particles in the range 50-75 μm showed a saturation magnetization 36% higher than the one formed from powder particles smaller than 50 μm. The phenomenon is explained in terms of changes in the magnetic environment of the particles as consequence of the presence of MWCNT.

  5. Magnetic binary nanofillers

    Energy Technology Data Exchange (ETDEWEB)

    Morales Mendoza, N. [INQUIMAE, CONICET-UBA, Ciudad Universitaria, Pab2, (C1428EHA) Bs As (Argentina); LPyMC, Dep. De Fisica, FCEN-UBA and IFIBA -CONICET, Ciudad Universitaria, Cap. Fed. (Argentina); Goyanes, S. [LPyMC, Dep. De Fisica, FCEN-UBA and IFIBA -CONICET, Ciudad Universitaria, Cap. Fed. (Argentina); Chiliotte, C.; Bekeris, V. [LBT, Dep. De Fisica, FCEN-UBA. Ciudad Universitaria, Pab1, C1428EGA CABA (Argentina); Rubiolo, G. [LPyMC, Dep. De Fisica, FCEN-UBA and IFIBA -CONICET, Ciudad Universitaria, Cap. Fed. (Argentina); Unidad de Actividad Materiales, CNEA, Av Gral. Paz 1499, San Martin (1650), Prov. de Bs As (Argentina); Candal, R., E-mail: candal@qi.fcen.uba.ar [INQUIMAE, CONICET-UBA, Ciudad Universitaria, Pab2, (C1428EHA) Bs As (Argentina); Escuela de Ciencia y Tecnologia, 3iA, Universidad de Gral. San Martin, San Martin, Prov. Bs As (Argentina)

    2012-08-15

    Magnetic binary nanofillers containing multiwall carbon nanotubes (MWCNT) and hercynite were synthesized by Chemical Vapor Deposition (CVD) on Fe/AlOOH prepared by the sol-gel method. The catalyst precursor was fired at 450 Degree-Sign C, ground and sifted through different meshes. Two powders were obtained with different particle sizes: sample A (50-75 {mu}m) and sample B (smaller than 50 {mu}m). These powders are composed of iron oxide particles widely dispersed in the non-crystalline matrix of aluminum oxide and they are not ferromagnetic. After reduction process the powders are composed of {alpha}-Fe nanoparticles inside hercynite matrix. These nanofillers are composed of hercynite containing {alpha}-Fe nanoparticles and MWCNT. The binary magnetic nanofillers were slightly ferromagnetic. The saturation magnetization of the nanofillers depended on the powder particle size. The nanofiller obtained from powder particles in the range 50-75 {mu}m showed a saturation magnetization 36% higher than the one formed from powder particles smaller than 50 {mu}m. The phenomenon is explained in terms of changes in the magnetic environment of the particles as consequence of the presence of MWCNT.

  6. A superconducting magnetic gear

    International Nuclear Information System (INIS)

    Campbell, A M

    2016-01-01

    A comparison is made between a magnetic gear using permanent magnets and superconductors. The objective is to see if there are any fundamental reasons why superconducting magnets should not provide higher power densities than permanent magnets. The gear is based on the variable permeability design of Attilah and Howe (2001 IEEE Trans. Magn. 37 2844–46) in which a ring of permanent magnets surrounding a ring of permeable pole pieces with a different spacing gives an internal field component at the beat frequency. Superconductors can provide much larger fields and forces but will saturate the pole pieces. However the gear mechanism still operates, but in a different way. The magnetisation of the pole pieces is now constant but rotates with angle at the beat frequency. The result is a cylindrical Halbach array which produces an internal field with the same symmetry as in the linear regime, but has an analytic solution. In this paper a typical gear system is analysed with finite elements using FlexPDE. It is shown that the gear can work well into the saturation regime and that the Halbach array gives a good approximation to the results. Replacing the permanent magnets with superconducting tapes can give large increases in torque density, and for something like a wind turbine a combined gear and generator is possible. However there are major practical problems. Perhaps the most fundamental is the large high frequency field which is inevitably present and which will cause AC losses. Also large magnetic fields are required, with all the practical problems of high field superconducting magnets in rotating machines. Nevertheless there are ways of mitigating these difficulties and it seems worthwhile to explore the possibilities of this technology further. (paper)

  7. On the measurement of magnetic viscosity

    Science.gov (United States)

    Serletis, C.; Efthimiadis, K. G.

    2012-08-01

    This work is an investigation of the experimental method used for measuring the magnetic viscosity in a hard ferromagnetic material, i.e. the recording of the magnetization under constant applied field and temperature, after the material has been magnetically saturated. It investigates how the experimental results are affected by the initial conditions of the method (saturation field, field change rate and field oscillation prior to its stabilization), and by minor variations of field and temperature during the recording. Based on the arising conclusions and the use of a more complex fitting function of measurements, the accuracy and repeatability of experimental results is improved.

  8. Electrical conductivity modeling in fractal non-saturated porous media

    Science.gov (United States)

    Wei, W.; Cai, J.; Hu, X.; Han, Q.

    2016-12-01

    The variety of electrical conductivity in non-saturated conditions is important to study electric conduction in natural sedimentary rocks. The electrical conductivity in completely saturated porous media is a porosity-function representing the complex connected behavior of single conducting phases (pore fluid). For partially saturated conditions, the electrical conductivity becomes even more complicated since the connectedness of pore. Archie's second law is an empirical electrical conductivity-porosity and -saturation model that has been used to predict the formation factor of non-saturated porous rock. However, the physical interpretation of its parameters, e.g., the cementation exponent m and the saturation exponent n, remains questionable. On basis of our previous work, we combine the pore-solid fractal (PSF) model to build an electrical conductivity model in non-saturated porous media. Our theoretical porosity- and saturation-dependent models contain endmember properties, such as fluid electrical conductivities, pore fractal dimension and tortuosity fractal dimension (representing the complex degree of electrical flowing path). We find the presented model with non-saturation-dependent electrical conductivity datasets indicate excellent match between theory and experiments. This means the value of pore fractal dimension and tortuosity fractal dimension change from medium to medium and depends not only on geometrical properties of pore structure but also characteristics of electrical current flowing in the non-saturated porous media.

  9. Preparation and magnetic characterization of Y-type hexaferrites containing zinc, cobalt and copper

    International Nuclear Information System (INIS)

    Bai Yang; Zhou Ji; Gui Zhilun; Yue Zhensing; Li Longtu

    2003-01-01

    Y-type hexaferrites series with Ba 2 Me 2 Fe 12 O 22 (Me=Zn, Co, Cu) has been prepared by the solid-state reaction method. Y-type polycrystalline hexaferrite powders were characterized by X-ray diffraction and the magnetic characteristics were investigated by vibrating samples magnetometer. Experimental results show that the substitution of Co for Zn leads to a decrease of saturation magnetization and an increase of magnetic anisotropy. At room temperature, saturation magnetization does not increase linearly as Zn content increases due to the effect of the thermal agitation. Saturation magnetization of the Zn-Cu Y-type ferrite exhibits the similar variational rule at room temperature. As Cu substitute for Co, the saturation magnetization and magnetic anisotropy all decrease. Cu modification can lower the single-phase formed temperature distinctly as the magnetic properties slightly debase

  10. Correcting saturation of detectors for particle/droplet imaging methods

    International Nuclear Information System (INIS)

    Kalt, Peter A M

    2010-01-01

    Laser-based diagnostic methods are being applied to more and more flows of theoretical and practical interest and are revealing interesting new flow features. Imaging particles or droplets in nephelometry and laser sheet dropsizing methods requires a trade-off of maximized signal-to-noise ratio without over-saturating the detector. Droplet and particle imaging results in lognormal distribution of pixel intensities. It is possible to fit a derived lognormal distribution to the histogram of measured pixel intensities. If pixel intensities are clipped at a saturated value, it is possible to estimate a presumed probability density function (pdf) shape without the effects of saturation from the lognormal fit to the unsaturated histogram. Information about presumed shapes of the pixel intensity pdf is used to generate corrections that can be applied to data to account for saturation. The effects of even slight saturation are shown to be a significant source of error on the derived average. The influence of saturation on the derived root mean square (rms) is even more pronounced. It is found that errors on the determined average exceed 5% when the number of saturated samples exceeds 3% of the total. Errors on the rms are 20% for a similar saturation level. This study also attempts to delineate limits, within which the detector saturation can be accurately corrected. It is demonstrated that a simple method for reshaping the clipped part of the pixel intensity histogram makes accurate corrections to account for saturated pixels. These outcomes can be used to correct a saturated signal, quantify the effect of saturation on a derived average and offer a method to correct the derived average in the case of slight to moderate saturation of pixels

  11. Analysis of an SEIR Epidemic Model with Saturated Incidence and Saturated Treatment Function

    Directory of Open Access Journals (Sweden)

    Jinhong Zhang

    2014-01-01

    Full Text Available The dynamics of SEIR epidemic model with saturated incidence rate and saturated treatment function are explored in this paper. The basic reproduction number that determines disease extinction and disease survival is given. The existing threshold conditions of all kinds of the equilibrium points are obtained. Sufficient conditions are established for the existence of backward bifurcation. The local asymptotical stability of equilibrium is verified by analyzing the eigenvalues and using the Routh-Hurwitz criterion. We also discuss the global asymptotical stability of the endemic equilibrium by autonomous convergence theorem. The study indicates that we should improve the efficiency and enlarge the capacity of the treatment to control the spread of disease. Numerical simulations are presented to support and complement the theoretical findings.

  12. Critical phenomena in magnetic vortex formation probed by noise spectroscopy

    International Nuclear Information System (INIS)

    Saitoh, E.; Harii, K.; Miyajima, H.; Yamaoka, T.

    2004-01-01

    Transition between a vortex magnetic state and a uniform magnetic state in a Ni 81 Fe 19 mesoscopic ring has been investigated in terms of resistive-noise spectroscopy. The observed low-frequency noise exhibits critical enhancement around the magnetization saturation. This noise enhancement can be argued from the viewpoint of the critical phenomena due to the chiral-symmetry breakdown of mesoscopic magnetic-structure, which can present a typical mechanism of symmetry transition of magnetic structure in mesoscopic ferromagnets

  13. Void fraction prediction in saturated flow boiling

    International Nuclear Information System (INIS)

    Francisco J Collado

    2005-01-01

    Full text of publication follows: An essential element in thermal-hydraulics is the accurate prediction of the vapor void fraction, or fraction of the flow cross-sectional area occupied by steam. Recently, the author has suggested to calculate void fraction working exclusively with thermodynamic properties. It is well known that the usual 'flow' quality, merely a mass flow rate ratio, is not at all a thermodynamic property because its expression in function of thermodynamic properties includes the slip ratio, which is a parameter of the process not a function of state. By the other hand, in the classic and well known expression of the void fraction - in function of the true mass fraction of vapor (also called 'static' quality), and the vapor and liquid densities - does not appear the slip ratio. Of course, this would suggest a direct procedure for calculating the void fraction, provided we had an accurate value of the true mass fraction of vapor, clearly from the heat balance. However the classic heat balance is usually stated in function of the 'flow' quality, what sounds really contradictory because this parameter, as we have noted above, is not at all a thermodynamic property. Then we should check against real data the actual relationship between the thermodynamic properties and the applied heat. For saturated flow boiling just from the inlet of the heated tube, and not having into account the kinetic and potential terms, the uniform applied heat per unit mass of inlet water and per unit length (in short, specific linear heat) should be closely related to a (constant) slope of the mixture enthalpy. In this work, we have checked the relation between the specific linear heat and the thermodynamic enthalpy of the liquid-vapor mixture using the actual mass fraction. This true mass fraction is calculated using the accurate measurements of the outlet void fraction taken during the Cambridge project by Knights and Thom in the sixties for vertical and horizontal

  14. Nitrogen Saturation in Highly Retentive Watersheds?

    Science.gov (United States)

    Daley, M. L.; McDowell, W. H.

    2009-12-01

    Watershed managers are often concerned with minimizing the amount of N delivered to N-limited estuaries and coastal zones. A major concern is that watersheds might reach N saturation, in which N delivered to coastal zones increases due to declines in the efficiency of N retention despite constant or even reduced N inputs. We have quantified long-term changes in N inputs (atmospheric deposition, imported food and agricultural fertilizers), outputs (N concentration and export) and retention in the urbanizing Lamprey River watershed in coastal NH. Overall, the Lamprey watershed is 70% forested, receives about 13.5 kg N/ha/yr and has a high rate of annual N retention (85%). Atmospheric deposition (8.7 kg/ha/yr) is the largest N input to the watershed. Of the 2.2 kg N/ha/yr exported in the Lamprey River, dissolved organic N (DON) is the dominant form (50% of total) and it varies spatially throughout the watershed with wetland cover. Nitrate accounts for 30% of the N exported, shows a statistically significant increase from 1999 to 2009, and its spatial variability in both concentration and export is related to human population density. In sub-basins throughout the Lamprey, inorganic N retention is high (85-99%), but the efficiency of N retention declines sharply with increased human population density and associated anthropogenic N inputs. N assimilation in the vegetation, denitrification to the atmosphere and storage in the groundwater pool could all be important contributors to the current high rates of N retention. The temporal and spatial patterns that we have observed in nitrate concentration and export are driven by increases in N inputs and impervious surfaces over time, but the declining efficiency of N retention suggests that the watershed may also be reaching N saturation. The downstream receiving estuary, Great Bay, already suffers from low dissolved oxygen levels and eelgrass loss in part due to N loading from the Lamprey watershed. Targeting and reducing

  15. Effect of pressure on magnetic properties of hexacyanochromates

    Czech Academy of Sciences Publication Activity Database

    Mitróová, Z.; MaŤaš, S.; Mihalik, M.; Zentková, M.; Arnold, Zdeněk; Kamarád, Jiří

    2008-01-01

    Roč. 113, č. 1 (2008), s. 469-472 ISSN 0587-4246 R&D Projects: GA AV ČR IAA100100632 Institutional research plan: CEZ:AV0Z10100521 Keywords : saturation moments and magnet ic susceptibilities * antiferromagnetics * molecular magnet Subject RIV: BM - Solid Matter Physics ; Magnet ism Impact factor: 0.321, year: 2008

  16. Electrical Machines Laminations Magnetic Properties: A Virtual Instrument Laboratory

    Science.gov (United States)

    Martinez-Roman, Javier; Perez-Cruz, Juan; Pineda-Sanchez, Manuel; Puche-Panadero, Ruben; Roger-Folch, Jose; Riera-Guasp, Martin; Sapena-Baño, Angel

    2015-01-01

    Undergraduate courses in electrical machines often include an introduction to their magnetic circuits and to the various magnetic materials used in their construction and their properties. The students must learn to be able to recognize and compare the permeability, saturation, and losses of these magnetic materials, relate each material to its…

  17. Empirical algorithms to predict aragonite saturation state

    Science.gov (United States)

    Turk, Daniela; Dowd, Michael

    2017-04-01

    Novel sensor packages deployed on autonomous platforms (Profiling Floats, Gliders, Moorings, SeaCycler) and biogeochemical models have a potential to increase the coverage of a key water chemistry variable, aragonite saturation state (ΩAr) in time and space, in particular in the under sampled regions of global ocean. However, these do not provide the set of inorganic carbon measurements commonly used to derive ΩAr. There is therefore a need to develop regional predictive models to determine ΩAr from measurements of commonly observed or/and non carbonate oceanic variables. Here, we investigate predictive skill of several commonly observed oceanographic variables (temperature, salinity, oxygen, nitrate, phosphate and silicate) in determining ΩAr using climatology and shipboard data. This will allow us to assess potential for autonomous sensors and biogeochemical models to monitor ΩAr regionally and globally. We apply the regression models to several time series data sets and discuss regional differences and their implications for global estimates of ΩAr.

  18. Saturated output tabletop x-ray lasers

    International Nuclear Information System (INIS)

    Dunn, J.; Osterheld, A.L.; Nilsen, J.; Hunter, J.R.; Li, Y.; Faenov, A.Ya.; Pikuz, T.A.; Shlyaptsev, N.

    2000-01-01

    The high efficiency method of transient collisional excitation has been successfully demonstrated for Ne-like and Ni-like ion x-ray laser schemes with small 5-10 J laser facilities. Our recent studies using the tabletop COMET (Compact Multipulse Terawatt) laser system at the Lawrence Livermore National Laboratory (LLNL) have produced several x-ray lasers operating in the saturation regime. Output energy of 10-15 (micro)J corresponding to a gL product of 18 has been achieved on the Ni-like Pd 4d → 4p transition at 147 (angstrom) with a total energy of 5-7 J in a 600 ps pulse followed by a 1.2 ps pulse. Analysis of the laser beam angular profile indicates that refraction plays an important role in the amplification and propagation process in the plasma column. We report further improvement in the extraction efficiency by varying a number of laser driver parameters. In particular, the duration of the second short pulse producing the inversion has an observed effect on the x-ray laser output

  19. SATURATED ZONE FLOW AND TRANSPORT MODEL ABSTRACTION

    International Nuclear Information System (INIS)

    B.W. ARNOLD

    2004-01-01

    The purpose of the saturated zone (SZ) flow and transport model abstraction task is to provide radionuclide-transport simulation results for use in the total system performance assessment (TSPA) for license application (LA) calculations. This task includes assessment of uncertainty in parameters that pertain to both groundwater flow and radionuclide transport in the models used for this purpose. This model report documents the following: (1) The SZ transport abstraction model, which consists of a set of radionuclide breakthrough curves at the accessible environment for use in the TSPA-LA simulations of radionuclide releases into the biosphere. These radionuclide breakthrough curves contain information on radionuclide-transport times through the SZ. (2) The SZ one-dimensional (I-D) transport model, which is incorporated in the TSPA-LA model to simulate the transport, decay, and ingrowth of radionuclide decay chains in the SZ. (3) The analysis of uncertainty in groundwater-flow and radionuclide-transport input parameters for the SZ transport abstraction model and the SZ 1-D transport model. (4) The analysis of the background concentration of alpha-emitting species in the groundwater of the SZ

  20. Saturation and stability of nonlinear photonic crystals

    International Nuclear Information System (INIS)

    Franco-Ortiz, M; Corella-Madueño, A; Rosas-Burgos, R A; Adrian Reyes, J; Avendaño, Carlos G

    2017-01-01

    We consider a one-dimensional photonic crystal made by an infinite set of nonlinear nematic films immersed in a linear dielectric medium. The thickness of each equidistant film is negligible and its refraction index depends continuously on the electric field intensity, giving rise to all the involved nonlinear terms, which joints from a starting linear index for negligible amplitudes to a final saturation index for extremely large field intensities. We show that the nonlinear exact solutions of this system form an intensity-dependent band structure which we calculate and analyze. Next, we ponder a finite version of this system; that is, we take a finite array of linear dielectric stacks of the same size separated by the same nonlinear extremely thin nematic slabs and find the reflection coefficients for this arrangement and obtain the dependence on the wave number and intensity of the incident wave. As a final step we analyze the stability of the analytical solutions of the nonlinear crystal by following the evolution of an additive amplitude to the analytical nonlinear solution we have found here. We discuss our results and state our conclusions. (paper)

  1. Saturated output tabletop X-ray lasers

    Energy Technology Data Exchange (ETDEWEB)

    Dunn, J.; Osterheld, A.L.; Nilsen, J.; Hunter, J.R. [Lawrence Livermore National Lab., CA (United States); Yuelin Li [Lawrence Livermore National Lab., CA (United States); ILSA, Lawrence Livermore National Lab., Livermore, CA (United States); Faenov, A.Ya.; Pikuz, T.A. [Lawrence Livermore National Lab., CA (United States); MISDC of VNIIFTRI, Mendeleevo (Russian Federation); Shlyaptsev, V.N. [Lawrence Livermore National Lab., CA (United States); DAS, Univ. of California Davis-Livermore, Livermore, CA (United States)

    2001-07-01

    The high efficiency method of transient collisional excitation has been successfully demonstrated for Ne-like and Ni-like ion X-ray laser schemes with small 5-10 J laser facilities. Our recent studies using the tabletop COMET (compact multipulse terawatt) laser system at the Lawrence livermore national laboratory (LLNL) have produced several X-ray lasers operating in the saturation regime. Output energy of 10-15 {mu}J corresponding to a gL product of 18 has been achieved on the Ni-like Pd 4d{yields}4p transition at 147 A with a total energy of 5-7 J in a 600 ps pulse followed by a 1.2 ps pulse. Analysis of the laser beam angular profile indicates that refraction plays an important role in the amplification and propagation process in the plasma column. We report further improvement in the extraction efficiency by varying a number of laser driver parameters. In particular, the duration of the second short pulse producing the inversion has an observed effect on the X-ray laser output. (orig.)

  2. The role of meson dynamics in nuclear matter saturation

    International Nuclear Information System (INIS)

    Goncalves, E.

    1988-01-01

    The problem of the saturation of nuclea matter in the non-relativistic limit of the model proposed by J.D. Walecka is studied. In the original context nuclear matter saturation is obtained as a direct consequence of relativistic effects and both scalar and vector mesons are treated statically. In the present work we investigate the effect of the meson dynamics for the saturation using a Born-Oppenheimer approximation for the ground state. An upper limit for the saturation curve of nuclear matter and are able to decide now essential is the relativistic treatment of the nucleons for this problem, is obtained. (author) [pt

  3. Magnetically nonlinear dynamic model of synchronous motor with permanent magnets

    International Nuclear Information System (INIS)

    Hadziselimovic, Miralem; Stumberger, Gorazd; Stumberger, Bojan; Zagradisnik, Ivan

    2007-01-01

    This paper deals with a magnetically nonlinear two-axis dynamic model of a permanent magnet synchronous motor (PMSM). The geometrical and material properties of iron core and permanent magnets, the effects of winding distribution, saturation, cross-saturation and slotting effects are, for the first time, simultaneously accounted for in a single two-axis dynamic model of a three-phase PMSM. They are accounted for by current- and position-dependent characteristics of flux linkages. These characteristics can be determined either experimentally or by the finite element (FE) computations. The results obtained by the proposed dynamic model show a very good agreement with the measured ones and those obtained by the FE computation

  4. Peculiarities of MCD C-term saturation behavior of the exchange coupled Co(II) dimers

    International Nuclear Information System (INIS)

    Ostrovsky, S.M.

    2011-01-01

    Graphical abstract: The change of sign of the MCD signal with temperature and magnetic field increase can take place. The origin of this peculiarity is explained by the strong orbital contribution. Highlights: → MCD C-term saturation behavior of the exchange coupled cobalt dimer. → Strong orbital contribution to the magneto-optical behavior. → Change of sign of the MCD signal with temperature and magnetic field increase. - Abstract: The MCD C-term saturation behavior of the exchange coupled octahedrally coordinated cobalt dimers is studied for different types of distortion of the local surrounding of each interacting ion. It was found that in the case of antiferromagnetic exchange interaction the change of sign of the MCD signal with temperature and magnetic field increase can take place. This signal behavior is not the result of overlapping of different electronic transitions and it is characteristic of an individual MCD line. The origin of this magneto-optical behavior is explained by the strong contribution coming from the unquenched orbital angular momenta of interacting cobalt ions. The found peculiarity is inherent to complexes composed of nonequivalent cobalt ions as well as to the dimeric complexes with the equivalent Co ions with nonparallel local axes.

  5. Can Polyphosphate Biochemistry Affect Biological Apatite Saturation?

    Science.gov (United States)

    Omelon, S. J.; Matsuura, N.; Gorelikov, I.; Wynnyckyj, C.; Grynpas, M. D.

    2010-12-01

    Phosphorus (P) is an important and limiting element for life. One strategy for storing ortho phosphates (Pi) is polymerization. Polymerized Pi's (polyphosphates: (PO3-)n: polyPs) serve as a Pi bank, as well as a catiion chelator, energy source, & regulator of responses to stresses in the stationary phase of culture growth and development1. PolyP biochemistry has been investigated in yeasts, bacteria & plants2. Bigeochemical cycling of P includes the condensation of Pi into pyro (P2O7-4), & polyPs, & the release of Pi from these compounds by the hydrolytic degradation of Pi from phosphomonoester bonds. Alkaline phosphatase (ALP) is one of the predominate enzymes for regenerating Pi in aquatic systems3, & it cleaves Pi from polyPs. ALP is also the enzyme associated with apatite biomineralization in vertebrates4. PolyP was proposed to be the ALP substrate in bone mineralization5. Where calcium ions are plentiful in many aquatic environments, there is no requirement for aquatic life to generate Ca-stores. However, terrestrial vertebrates benefit from a bioavailable Ca-store such as apatite. The Pi storage strategy of polymerizing PO4-3 into polyPs dovetails well with Ca-banking, as polyPs sequester Ca, forming a neutral calcium polyphosphate (Ca-polyP: (Ca(PO3)2)n) complex. This neutral complex represents a high total [Ca+2] & [PO4-3], without the threat of inadvertent apatite precipitation, as the free [Ca+2] & [PO4-3], and therefore apatite saturation, are zero. Recent identification of polyP in regions of bone resorption & calcifying cartilage5 suggests that vertebrates may use polyP chemistry to bank Ca+2 and PO4-3. In vitro experiments with nanoparticulate Ca-polyP & ALP were undertaken to determine if carbonated apatite could precipitate from 1M Ca-polyP in Pi-free “physiological fluid” (0.1 M NaCl, 2 mM Ca+2, 0.8 mM Mg+2, pH ~8.0 ±0.5, 37 °C), as this is estimated to generate the [Ca+2] & [PO4-3] required to form the apatite content of bone tissue

  6. A Perturbation Analysis of Harmonics Generation from Saturated Elements in Power Systems

    Science.gov (United States)

    Kumano, Teruhisa

    Nonlinear phenomena such as saturation in magnetic flux give considerable effects in power system analysis. It is reported that a failure in a real 500kV system triggered islanding operation, where resultant even harmonics caused malfunctions in protective relays. It is also reported that the major origin of this wave distortion is nothing but unidirectional magnetization of the transformer iron core. Time simulation is widely used today to analyze this type of phenomena, but it has basically two shortcomings. One is that the time simulation takes two much computing time in the vicinity of inflection points in the saturation characteristic curve because certain iterative procedure such as N-R (Newton-Raphson) should be used and such methods tend to be caught in an ill conditioned numerical hunting. The other is that such simulation methods sometimes do not help intuitive understanding of the studied phenomenon because the whole nonlinear equations are treated in a matrix form and not properly divided into understandable parts as done in linear systems. This paper proposes a new computation scheme which is based on so called perturbation method. Magnetic saturation in iron cores in a generator and a transformer are taken into account. The proposed method has a special feature against the first shortcoming of the N-R based time simulation method stated above. In the proposed method no iterative process is used to reduce the equation residue but uses perturbation series, which means free from the ill condition problem. Users have only to calculate each perturbation terms one by one until he reaches necessary accuracy. In a numerical example treated in the present paper the first order perturbation can make reasonably high accuracy, which means very fast computing. In numerical study three nonlinear elements are considered. Calculated results are almost identical to the conventional Newton-Raphson based time simulation, which shows the validity of the method. The

  7. Magnetic properties of natural pyrrhotite Part I: Behaviour

    NARCIS (Netherlands)

    Dekkers, M.J.

    1988-01-01

    The grain-size dependence of the initial susceptibility (X 1~),saturation magnetization (.1,), saturation remanence (J~),coercive force (He), remanent coercive force (Hcr) and remanent acquisition coercive force (Hcr’), is reported for four natural pyrrhotites in a grain-size range from 250

  8. Nanocrystalline permanent magnets with enhanced properties

    International Nuclear Information System (INIS)

    Leonowicz, M.

    2002-01-01

    Parameters of permanent magnets result from the combination of intrinsic properties such as saturation magnetization, magnetic exchange, and magnetocrystalline energy, as well as microstructural parameters such as phase structure, grain size, and orientation. Reduction of grain size into nanocrystalline regime (∼ 50 nm) leads to the enhanced remanence which derives from ferromagnetic exchange coupling between highly refined grains. In this study the fundamental phenomena, quantities, and structure parameters, which define nanophase permanent magnets are presented and discussed. The theoretical considerations are confronted with experimental data for nanocrystalline Sm-Fe-N type permanent magnets. (author)

  9. Temperature dependence of the magnetization of canted spin structures

    DEFF Research Database (Denmark)

    Jacobsen, Henrik; Lefmann, Kim; Brok, Erik

    2012-01-01

    Numerous studies of the low-temperature saturation magnetization of ferrimagnetic nanoparticles and diamagnetically substituted ferrites have shown an anomalous temperature dependence. It has been suggested that this is related to freezing of canted magnetic structures. We present models for the ......Numerous studies of the low-temperature saturation magnetization of ferrimagnetic nanoparticles and diamagnetically substituted ferrites have shown an anomalous temperature dependence. It has been suggested that this is related to freezing of canted magnetic structures. We present models...... for the temperature dependence of the magnetization of a simple canted spin structure in which relaxation can take place at finite temperatures between spin configurations with different canting angles. We show that the saturation magnetization may either decrease or increase with decreasing temperature, depending...

  10. Magnetoresistance and magnetic breakdown phenomenon in amorphous magnetic alloys

    International Nuclear Information System (INIS)

    Chen Hui-yu; Gong Xiao-yu

    1988-01-01

    Transverse magnetoresistance in amorphous magnetic alloys (Fe/sub 1-//sub x/CO/sub x/) 82 Cu/sub 0.4/Si/sub 4.4/B/sub 13.2/ were measured at room temperature and in the magnetic field range 0--15 kOe. For large magnetic field, three different functional dependences of magnetoresistance on magnetic field strength have been found as follows: (1) Δrho/rho approaches saturation. (2) Δrho/rho increases proportionally to H 2 . (3) For x = 0.15, a sharp Δrho/rho peak appears at a certain magnetic field strength in spatial angular orientation of both magnetic field and electric currents. Case (3) is a magnetic breakdown phenomenon. Magnetic breakdown occurs at the gap between the spin-up and spin-down sheets of the Fermi surface. This gap is the spin-orbit gap and its magnitude is a sensitive function of magnetization. Hence the magnitude and width of the magnetoresistance peak and the magnetic field strength at the peak point are functions of angular orientation of both magnetic field and electric current

  11. Quantum Theory of Rare-Earth Magnets

    Science.gov (United States)

    Miyake, Takashi; Akai, Hisazumi

    2018-04-01

    Strong permanent magnets mainly consist of rare earths (R) and transition metals (T). The main phase of the neodymium magnet, which is the strongest magnet, is Nd2Fe14B. Sm2Fe17N3 is another magnet compound having excellent magnetic properties comparable to those of Nd2Fe14B. Their large saturation magnetization, strong magnetocrystalline anisotropy, and high Curie temperature originate from the interaction between the T-3d electrons and R-4f electrons. This article discusses the magnetism of rare-earth magnet compounds. The basic theory and first-principles calculation approaches for quantitative description of the magnetic properties are presented, together with applications to typical compounds such as Nd2Fe14B, Sm2Fe17N3, and the recently synthesized NdFe12N.

  12. Magnetic phase shift reconstruction for uniformly magnetized nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Akhtari-Zavareh, Azadeh [Department of Physics, Simon Fraser University, Burnaby, British Columbia (Canada); De Graef, Marc [Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA (United States); Kavanagh, Karen L. [Department of Physics, Simon Fraser University, Burnaby, British Columbia (Canada)

    2017-01-15

    A new analytical model is developed for the magnetic phase shift of uniformly magnetized nanowires with ideal cylindrical geometry. The model is applied to experimental data from off-axis electron holography measurements of the phase shift of CoFeB nanowires, and the saturation induction of a selected wire, as well as its radius, aspect ratio, position and orientation, is determined by fitting the model parameters. The saturation induction value of 1.7 T of the CoFeB nanowire is found to be similar, to be within the measurement error, to values reported in the literature. - Highlights: • We describe a mathematical model for the magnetic phase shift of a cylindrical nanowire. • We discuss electron holography experiments on magnetic nanowires. • We obtain an accurate fit of the measured magnetic phase shift profile. • We extract the magnetic induction of the nanowire from the phase shift model. • The magnetic induction of 1.7 T agrees well with literature results.

  13. In-situ gas hydrate hydrate saturation estimated from various well logs at the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

    Science.gov (United States)

    Lee, M.W.; Collett, T.S.

    2011-01-01

    In 2006, the U.S. Geological Survey (USGS) completed detailed analysis and interpretation of available 2-D and 3-D seismic data and proposed a viable method for identifying sub-permafrost gas hydrate prospects within the gas hydrate stability zone in the Milne Point area of northern Alaska. To validate the predictions of the USGS and to acquire critical reservoir data needed to develop a long-term production testing program, a well was drilled at the Mount Elbert prospect in February, 2007. Numerous well log data and cores were acquired to estimate in-situ gas hydrate saturations and reservoir properties.Gas hydrate saturations were estimated from various well logs such as nuclear magnetic resonance (NMR), P- and S-wave velocity, and electrical resistivity logs along with pore-water salinity. Gas hydrate saturations from the NMR log agree well with those estimated from P- and S-wave velocity data. Because of the low salinity of the connate water and the low formation temperature, the resistivity of connate water is comparable to that of shale. Therefore, the effect of clay should be accounted for to accurately estimate gas hydrate saturations from the resistivity data. Two highly gas hydrate-saturated intervals are identified - an upper ???43 ft zone with an average gas hydrate saturation of 54% and a lower ???53 ft zone with an average gas hydrate saturation of 50%; both zones reach a maximum of about 75% saturation. ?? 2009.

  14. Suppression of magnetic islands by rf-driven currents

    International Nuclear Information System (INIS)

    Reiman, A.H.

    1982-06-01

    The quasilinear theory for the saturation of nonlinear tearing modes is modified to include rf driven currents. It is shown that the presence of lower hybrid driven currents can strongly suppress the growth of magnetic islands

  15. Variable Permanent Magnet Quadrupole

    International Nuclear Information System (INIS)

    Mihara, T.; Iwashita, Y.; Kyoto U.; Kumada, M.; NIRS, Chiba; Spencer, C.M.; SLAC

    2007-01-01

    A permanent magnet quadrupole (PMQ) is one of the candidates for the final focus lens in a linear collider. An over 120 T/m strong variable permanent magnet quadrupole is achieved by the introduction of saturated iron and a 'double ring structure'. A fabricated PMQ achieved 24 T integrated gradient with 20 mm bore diameter, 100 mm magnet diameter and 20 cm pole length. The strength of the PMQ is adjustable in 1.4 T steps, due to its 'double ring structure': the PMQ is split into two nested rings; the outer ring is sliced along the beam line into four parts and is rotated to change the strength. This paper describes the variable PMQ from fabrication to recent adjustments

  16. Saturation and beaming in astrophysical masers. II. The fully saturated limit

    International Nuclear Information System (INIS)

    Alcock, C.; Ross, R.R.; College of the Holy Cross, Worcester, MA)

    1985-01-01

    Radiative transfer in fully saturated maser clouds has been investigated using the four-stream model equations of Alcock and Ross (1985). It is shown that a modest elongation of the maser cloud produces a substantial asymmetry in the maser output. The ratio of output fluxes in different directions is a strong function of the ratio of the corresponding chord lengths across the cloud. Arguments are presented that the asymmetries reported here for the four-stream models closely mimic the asymmetries that should be expected in a real master cloud. 10 references

  17. Quantitative 1D saturation profiles on chalk by NMR

    DEFF Research Database (Denmark)

    Olsen, Dan; Topp, Simon; Stensgaard, Anders

    1996-01-01

    Quantitative one-dimensional saturation profiles showing the distribution of water and oil in chalk core samples are calculated from NMR measurements utilizing a 1D CSI spectroscopy pulse sequence. Saturation profiles may be acquired under conditions of fluid flow through the sample. Results reveal...

  18. Gain characteristics of a saturated fiber optic parametric amplifier

    DEFF Research Database (Denmark)

    Rottwitt, Karsten; Lorenzen, Michael Rodas; Noordegraaf, Danny

    2008-01-01

    In this work we discuss saturation performance of a fiber optic parametric amplifier. A simple numerical model is described and applied to specific cases. A system experiment using a saturated amplifier illustrates a 4 dB improvement in required signal to noise ratio for a fixed bit error ratio....

  19. On the spin saturation and thermal properties of nuclear matter

    International Nuclear Information System (INIS)

    Hassan, M.Y.M.; Ramadan, S.

    1983-12-01

    The binding energy and the incompressibility of nuclear matter with degree of spin saturation D is calculated using the Skyrme interaction and two forms of a velocity dependent effective potential. The effect of the degree of spin saturation D on the thermal properties of nuclear matter is also discussed. It is found that generally the pressure decreases with increasing D. (author)

  20. Comparison of empirical models and laboratory saturated hydraulic ...

    African Journals Online (AJOL)

    Numerous methods for estimating soil saturated hydraulic conductivity exist, which range from direct measurement in the laboratory to models that use only basic soil properties. A study was conducted to compare laboratory saturated hydraulic conductivity (Ksat) measurement and that estimated from empirical models.

  1. Saturated hydraulic conductivity values of some forest soils of ...

    African Journals Online (AJOL)

    A simple falling-head method is presented for the laboratory determination of saturated hydraulic conductivity of some forest soils of Ghana. Using the procedure, it was found that saturated hydraulic conductivity was positively and negatively correlated with sand content and clay content, respectively, both at P = 0.05 level.

  2. Stability and stabilization of linear systems with saturating actuators

    CERN Document Server

    Tarbouriech, Sophie; Gomes da Silva Jr, João Manoel; Queinnec, Isabelle

    2011-01-01

    Gives the reader an in-depth understanding of the phenomena caused by the more-or-less ubiquitous problem of actuator saturation. Proposes methods and algorithms designed to avoid, manage or overcome the effects of actuator saturation. Uses a state-space approach to ensure local and global stability of the systems considered. Compilation of fifteen years' worth of research results.

  3. Serum albumin--a non-saturable carrier

    DEFF Research Database (Denmark)

    Brodersen, R; Honoré, B; Larsen, F G

    1984-01-01

    The shape of binding isotherms for sixteen ligands to human serum albumin showed no signs of approaching saturation at high ligand concentrations. It is suggested that ligand binding to serum albumin is essentially different from saturable binding of substrates to enzymes, of oxygen to haemoglobi...

  4. Input saturation in nonlinear multivariable processes resolved by nonlinear decoupling

    Directory of Open Access Journals (Sweden)

    Jens G. Balchen

    1995-04-01

    Full Text Available A new method is presented for the resolution of the problem of input saturation in nonlinear multivariable process control by means of elementary nonlinear decoupling (END. Input saturation can have serious consequences particularly in multivariable control because it may lead to very undesirable system behaviour and quite often system instability. Many authors have searched for systematic techniques for designing multivariable control systems in which saturation may occur in any of the control variables (inputs, manipulated variables. No generally accepted method seems to have been presented so far which gives a solution in closed form. The method of elementary nonlinear decoupling (END can be applied directly to the case of saturation control variables by deriving as many control strategies as there are combinations of saturating control variables. The method is demonstrated by the multivariable control of a simulated Fluidized Catalytic Cracker (FCC with very convincing results.

  5. Convective hydromagnetic instabilities of a power-law liquid saturating a porous medium: Flux conditions

    Science.gov (United States)

    Chahtour, C.; Ben Hamed, H.; Beji, H.; Guizani, A.; Alimi, W.

    2018-01-01

    We investigate how an external imposed magnetic field affects thermal instability in a horizontal shallow porous cavity saturated by a non-Newtonian power-law liquid. The magnetic field is assumed to be constant and parallel to the gravity. A uniform heat flux is applied to the horizontal walls of the layer while the vertical walls are adiabatic. We use linear stability analysis to find expressions for the critical Rayleigh number as a function of the power-law index and the intensity of the magnetic field. We use nonlinear parallel flow theory to find some explicit solutions of the problem, and we use finite difference numerical simulations to solve the full nonlinear equations. We show how the presence of magnetic field alters the known hydrodynamical result of Newtonian flows and power-law flows and how it causes the presence of subcritical finite amplitude convection for both pseudoplastic and dilatant fluids. We also show that in the limit of very strong magnetic field, the dissipation of energy by Joule effect dominates the dissipation of energy by shear stress and gives to the liquid an inviscid character.

  6. Magnets and magnetic materials

    International Nuclear Information System (INIS)

    Meuris, Ch.; Rifflet, J.M.

    2007-01-01

    The Large Hadron Collider (LHC), the world's largest highest-energy particle collider that the CERN plans to commission in 2008, gets a double boost from superconducting magnet technology. Superconducting magnets are first used to guide the particles scheduled for collision through the accelerator, and then to observe the events triggered by the collision inside giant detectors in a known magnetic field. Despite the installation's massive dimensions, all this is done with minimal expenditure of energy. (author)

  7. Elastoplastic model for unsaturated, quasi-saturated and fully saturated fine soils

    Directory of Open Access Journals (Sweden)

    Lai Ba Tien

    2016-01-01

    Full Text Available In unsaturated soils, the gaseous phase is commonly assumed to be continuous. This assumption is no more valid at high saturation ratio. In that case, air bubbles and pockets can be trapped in the porous network by the liquid phase and the gas phase becomes discontinuous. This trapped air reduces the apparent compressibility of the pore fluid and affect the mechanical behavior of the soil. Although it is trapped in the pores, its dissolution can take place. Dissolved air can migrate through the pore space, either by following the flow of the fluid or by diffusion. In this context, this paper present a hydro mechanical model that separately considers the kinematics and the mechanical behavior of each fluid species (eg liquid water, dissolved air, gaseous air and the solid matrix. This new model was implemented in a C++ code. Some numerical simulations are performed to demonstrate the ability of this model to reproduce a continuous transition of unsaturated to saturated states.

  8. Magnetization, magnetic susceptibility, effective magnetic moment of Fe3+ ions in Bi25FeO39 ferrite

    International Nuclear Information System (INIS)

    Zatsiupa, A.A.; Bashkirov, L.A.; Troyanchuk, I.O.; Petrov, G.S.; Galyas, A.I.; Lobanovsky, L.S.; Truhanov, S.V.

    2014-01-01

    Magnetic susceptibility for ferrite Bi 25 FeO 39 is measured at 5–950 K in the magnetic field of 0.86 T. It is shown that Bi 25 FeO 39 is paramagnetic in the temperature range 5−950 K. The saturation magnetization is equal to 5.04μ B per formula unit at 5 K in a magnetic field of 10 T. It is found that at 5−300 K the effective magnetic moment of Fe 3+ ions in Bi 25 FeO 39 is equal to 5.82μ B . - Graphical abstract: The dependence of the magnetization (n, μ B ) on the magnetic field for one formula unit of Bi 25 FeO 39 at 5 K. - Highlights: • Magnetic susceptibility for Bi 25 FeO 39 is measured at 5–950 K in the magnetic field of 0.86 T. • It is shown that Bi 25 FeO 39 is paramagnetic in the temperature range 5−950 K. • The saturation magnetization is equal to 5.04μ B per formula unit at 5 K in a magnetic field of 10 T

  9. Influence of helical external driven current on nonlinear resistive tearing mode evolution and saturation in tokamaks

    Science.gov (United States)

    Zhang, W.; Wang, S.; Ma, Z. W.

    2017-06-01

    The influences of helical driven currents on nonlinear resistive tearing mode evolution and saturation are studied by using a three-dimensional toroidal resistive magnetohydrodynamic code (CLT). We carried out three types of helical driven currents: stationary, time-dependent amplitude, and thickness. It is found that the helical driven current is much more efficient than the Gaussian driven current used in our previous study [S. Wang et al., Phys. Plasmas 23(5), 052503 (2016)]. The stationary helical driven current cannot persistently control tearing mode instabilities. For the time-dependent helical driven current with f c d = 0.01 and δ c d < 0.04 , the island size can be reduced to its saturated level that is about one third of the initial island size. However, if the total driven current increases to about 7% of the total plasma current, tearing mode instabilities will rebound again due to the excitation of the triple tearing mode. For the helical driven current with time dependent strength and thickness, the reduction speed of the radial perturbation component of the magnetic field increases with an increase in the driven current and then saturates at a quite low level. The tearing mode is always controlled even for a large driven current.

  10. Nonlinear saturation of the trapped-ion mode by mode coupling in two dimensions

    International Nuclear Information System (INIS)

    Cohen, B.I.; Tang, W.M.

    1977-01-01

    A study of the nonlinear saturation by mode coupling of the dissipative trapped-ion mode is presented in which both radial and poloidal variations are considered. The saturation mechanism consists of the nonlinear coupling via E x B convection of energy from linearly unstable modes to stable modes. Stabilization is provided at short poloidal wavelengths by Landau damping from trapped and circulating ions, at short radial wavelengths by effects associated with the finite ion banana excursions and at long wavelengths by ion collisions. A one-dimensional, nonlinear partial differential equation for the electrostatic potential derived in earlier work is extended to two dimensions and to third order in amplitude. Included systematically are kinetic effects, e.g., Landau damping and its spatial dependence due to magnetic shear. The stability and accessibility of equilibria are considered in detail for cases far from as well as close to marginal stability. In the first case three-wave interactions are found to be important when the spectrum of unstable modes is sufficiently narrow. In the latter case, it is found that for a single unstable mode, a four-wave interaction can provide the dominant saturation mechanism. Cross-field transport is calculated, and the scaling of results is considered for tokamak parameters

  11. Synthesis and characterization of ultrafine well-dispersed magnetic nanoparticles

    International Nuclear Information System (INIS)

    Liu, Z.L.; Wang, H.B.; Lu, Q.H.; Du, G.H.; Peng, L.; Du, Y.Q.; Zhang, S.M.; Yao, K.L.

    2004-01-01

    Ultrafine well-dispersed magnetic nanoparticles were directly prepared in aqueous solution using controlled coprecipitation method. The structure, size, size distributions and magnetic properties of the magnetic nanoparticles, characterized by TEM, XRD and VSM, indicated the formation of single domain nanoparticles with average size smaller than 5 nm. The magnetic nanoparticles show superparamagnetism and a lower saturation magnetization is found as a consequence of smaller particle size. The relevant conditions for obtaining these magnetic colloids are discussed and the so-prepared magnetic nanoparticles are stable in a wide pH range

  12. On the propagation of a coupled saturation and pressure front

    Energy Technology Data Exchange (ETDEWEB)

    Vasco, D. W.

    2010-12-01

    Using an asymptotic technique, valid for a medium with smoothly varying heterogeneity, I derive an expression for the velocity of a propagating, coupled saturation and pressure front. Due to the nonlinearity of the governing equations, the velocity of the propagating front depends upon the magnitude of the saturation and pressure changes across the front in addition to the properties of the medium. Thus, the expression must be evaluated in conjunction with numerical reservoir simulation. The propagation of the two-phase front is governed by the background saturation distribution, the saturation-dependent component of the fluid mobility, the porosity, the permeability, the capillary pressure function, the medium compressibility, and the ratio of the slopes of the relative permeability curves. Numerical simulation of water injection into a porous layer saturated with a nonaqueous phase liquid indicates that two modes of propagation are important. The fastest mode of propagation is a pressure-dominated disturbance that travels through the saturated layer. This is followed, much later, by a coupled mode with a large saturation change. These two modes are also observed in a simulation using a heterogeneous porous layer. A comparison between the propagation times estimated from the results of the numerical simulation and predictions from the asymptotic expression indicates overall agreement.

  13. Magnetism and magnetic materials

    International Nuclear Information System (INIS)

    1990-01-01

    It describes the actual status of physics in Brazil concerning the study of magnetism and magnetic materials. It gives an overview of different research groups in Brazil, their needs, as well as the investments needed to improve the area. (A.C.A.S.)

  14. Quantification of the magnetization-transfer contrast effect: can it yield additional information in differentiation of musculoskeletal lesions particularly in separation of benign from malignant lesions

    International Nuclear Information System (INIS)

    Vahlensieck, M.; Traeber, F.; Schild, H.; Gieseke, J.

    1999-01-01

    Purpose: To investigate the potential information of the amount of magnetization-transfer effect in musculoskeletal lesions and to compare MT ratios from benign and malignant musculoskeletal lesions. Material and Method: 49 patients with malignant tumors (3 osteosarcoma, 3 malignant fibrous histiocytoma, 4 chondrosarcoma, 2 Ewing sarcomas) and benign lesions (8 chondroma, 2 fibrous dysplasia, 3 osteoid-osteoma, 6 ganglion cyst, 3 cyst, 3 osteomyelitis, 4 tendinitis, 3 rotator cuff tear, 5 scar tissue) were scanned using routine MRI protocols including T 1 - and T 2 -weighted spin echo as well as T 2 *-weighted gradient echo (FFE) sequences at 1.5 Tesla (ACS II, Philips Medical). Additionally MTC images were generated by combining the FFE sequence and the off-resonance MT technique (-1500 Hz off-resonance frequency, 1770 flip angle and 50 ms pulse duration). MT ratios were calculated as SI o -SI m /SI o . Results: The MT ratio of benign lesions was 26±15%, that of malignant lesions was 22±6%. The difference was statistically not significant. As expected muscle showed a high MT ratio of 50±8%. Scar tissue demonstrated an MT ratio of 39±16% which was significantly higher than the tumor MT ratios. Conclusion: MTC (MT ratios) failed to show significant differences between benign and malignant lesions as was expected due to basic differences in cellularity, rate of mitosis and chromatin content. MTC might however gain more importance in separating scar tissue from recurrent tumor in the future. (orig.) [de

  15. Two dimensional magnetic field calculations for the SSC dipole magnets

    International Nuclear Information System (INIS)

    Krefta, M.P.; Pavlik, D.

    1991-01-01

    In this work two-dimensional methods are used to calculate the magnetic fields throughout the cross section of a SSC dipole magnet. Analytic techniques, which are based on closed form solutions to the defining field equations, are used to calculate the multipole content for any specified conductor positioning. The method is extended to investigate the effects of radial slots or keyways in the iron yoke. The multipole components of field, directly attributable to the slots or keyways, are examined as a function of size and location. It is shown that locating the slots or keyways at the magnet pole centers has a large effect on the multipole components; whereas, locating the keyways between the magnet poles has little effect on any of the multipoles. The investigation of nonlinear effects such as ferromagnetic saturation or superconductor magnetization relies on the use of numerical methods such as the finite element method. The errors associated with these codes are explained in terms of numerical round-off, spatial discretization error and the representation of distant boundaries. A method for increasing the accuracy of the multipole calculation from finite element solutions is set forth. It is shown that calculated multipole coefficients are sensitive to boundary conditions external to the cold mass during conditions of magnetic saturation

  16. Magnetic patterning by means of ion irradiation and implantation

    International Nuclear Information System (INIS)

    Fassbender, J.; McCord, J.

    2008-01-01

    A pure magnetic patterning by means of ion irradiation which relies on a local modification of the magnetic anisotropy of a magnetic multilayer structure has been first demonstrated in 1998. Since then also other magnetic properties like the interlayer exchange coupling, the exchange bias effect, the magnetic damping behavior and the saturation magnetization to name a few have also been demonstrated to be affected by ion irradiation or ion implantation. Consequently, all these effects can be used if combined with a masking technique or employing direct focused ion beam writing for a magnetic patterning and thus an imprinting of an artificial magnetic domain structure, which subsequently modifies the integral magnetization reversal behavior or the magnetization dynamics of the film investigated. The present review will summarize how ion irradiation and implantation can affect the magnetic properties by means of structural modifications. The main part will cover the present status with respect to the pure magnetic patterning of micro- and nano structures

  17. Factors influencing fast low angle positive contrast steady-state free precession (FLAPS) magnetic resonance imaging

    International Nuclear Information System (INIS)

    Dharmakumar, Rohan; Koktzoglou, Ioannis; Li Debiao

    2007-01-01

    The presence of susceptibility-shifting media can lead to signal voids in magnetic resonance images. While signal voids have been traditionally used to detect such magnetic perturbers, selective magnetic resonance imaging of off-resonant spins surrounding susceptibility-shifted media allows for them to be visualized as hyper-intense (positive contrast) regions. These positive contrast methods can potentially improve the detection conspicuity of magnetic perturbers against regions that appear dark due to the absence of protons, such as air. Recently, a fast low angle positive contrast steady-state free precession (FLAPS) technique has been proposed as a positive contrast imaging method. This work systematically evaluates the contrast characteristics and acquisition strategies of FLAPS-based imaging from the standpoint of imaging parameters and physical properties of the magnetic perturbers. Results show that scan parameters (T R , flip angle, B 0 ), physical properties of the perturber (size and concentration of shift reagent) and the ratio of the relaxation constants (T 1 /T 2 ) of the medium are significant factors influencing the FLAPS-based positive contrast

  18. Macroscopic simulation of isotropic permanent magnets

    International Nuclear Information System (INIS)

    Bruckner, Florian; Abert, Claas; Vogler, Christoph; Heinrichs, Frank; Satz, Armin; Ausserlechner, Udo; Binder, Gernot; Koeck, Helmut; Suess, Dieter

    2016-01-01

    Accurate simulations of isotropic permanent magnets require to take the magnetization process into account and consider the anisotropic, nonlinear, and hysteretic material behaviour near the saturation configuration. An efficient method for the solution of the magnetostatic Maxwell equations including the description of isotropic permanent magnets is presented. The algorithm can easily be implemented on top of existing finite element methods and does not require a full characterization of the hysteresis of the magnetic material. Strayfield measurements of an isotropic permanent magnet and simulation results are in good agreement and highlight the importance of a proper description of the isotropic material. - Highlights: • Simulations of isotropic permanent magnets. • Accurate calculation of remanence magnetization and strayfield. • Comparison with strayfield measurements and anisotropic magnet simulations. • Efficient 3D FEM–BEM coupling for solution of Maxwell equations.

  19. Lithological controls on gas hydrate saturation: Insights from signal classification of NMR downhole data

    Science.gov (United States)

    Bauer, Klaus; Kulenkampff, Johannes; Henninges, Jan; Spangenberg, Erik

    2016-04-01

    Nuclear magnetic resonance (NMR) downhole data are analyzed with a new strategy to study gas hydrate-bearing sediments in the Mackenzie Delta (NW Canada). NMR logging is a powerful tool to study geological reservoir formations. The measurements are based on interactions between the magnetic moments of protons in geological formation water and an external magnetic field. Inversion of the measured raw data provides so-called transverse relaxation time (T2) distribution curves or spectra. Different parts of the T2 curve are related with distinct pore radii and corresponding fluid components. A common practice in the analysis of T2 distribution curves is to extract single-valued parameters such as apparent total porosity. Moreover, the derived total NMR apparent porosity and the gamma-gamma density log apparent porosity can be combined to estimate gas hydrate saturation in hydrate-bearing sediments. To avoid potential loss of information, in our new approach we analyze the entire T2 distribution curves as quasi-continuous signals to characterize the rock formation. The approach is applied to NMR data measured in gas hydrate research well Mallik 5L-38. We use self-organizing maps, a neural network clustering technique, to subdivide the data set of NMR T2 distribution curves into classes with a similar and distinctive signal shape. The method includes (1) preparation of data vectors, (2) unsupervised learning, (3) cluster definition, and (4) classification and depth mapping of all NMR signals. Each signal class thus represents a specific pore size distribution which can be interpreted in terms of distinct lithologies and reservoir types. A key step in the interpretation strategy is to reconcile the NMR classes with other log data not considered in the clustering analysis, such as gamma ray, photo-electric factor, hydrate saturation, and other logs. Our results defined six main lithologies within the target zone. Gas hydrate layers were recognized by their low signal

  20. Lithological control on gas hydrate saturation as revealed by signal classification of NMR logging data

    Science.gov (United States)

    Bauer, Klaus; Kulenkampff, Johannes; Henninges, Jan; Spangenberg, Erik

    2015-09-01

    In this paper, nuclear magnetic resonance (NMR) downhole logging data are analyzed with a new strategy to study gas hydrate-bearing sediments in the Mackenzie Delta (NW Canada). In NMR logging, transverse relaxation time (T2) distribution curves are usually used to determine single-valued parameters such as apparent total porosity or hydrocarbon saturation. Our approach analyzes the entire T2 distribution curves as quasi-continuous signals to characterize the rock formation. We apply self-organizing maps, a neural network clustering technique, to subdivide the data set of NMR curves into classes with a similar and distinctive signal shape. The method includes (1) preparation of data vectors, (2) unsupervised learning, (3) cluster definition, and (4) classification and depth mapping of all NMR signals. Each signal class thus represents a specific pore size distribution which can be interpreted in terms of distinct lithologies and reservoir types. A key step in the interpretation strategy is to reconcile the NMR classes with other log data not considered in the clustering analysis, such as gamma ray, hydrate saturation, and other logs. Our results defined six main lithologies within the target zone. Gas hydrate layers were recognized by their low signal amplitudes for all relaxation times. Most importantly, two subtypes of hydrate-bearing shaly sands were identified. They show distinct NMR signals and differ in hydrate saturation and gamma ray values. An inverse linear relationship between hydrate saturation and clay content was concluded. Finally, we infer that the gas hydrate is not grain coating, but rather, pore filling with matrix support is the preferred growth habit model for the studied formation.

  1. Magnetization transfer MR of cerebrovascular disorders using calculated images

    Energy Technology Data Exchange (ETDEWEB)

    Enomoto, Kyoko; Watabe, Tsuneya; Amanuma, Makoto; Heshiki, Atsuko [Saitama Medical School, Moroyama, Saitama (Japan)

    1997-06-01

    This study applied a magnetization transfer contrast method to patients with cerebrovascular disorders. A 1.5 T superconducting MR unit was used, and magnetization transfer ratio (MTR) images were calculated by evaluating two paired images before and after off-resonance gradient echo pulse sequences. The normal white matter showed the highest MTRs, CSF the lowest, and gray matter, intermediate. Cerebral ischemic patients showed two patterns according to the chronological stage of the affected area. Lesions in the acute and subacute stages revealed higher transfer rates than those in the chronic stage. Patients with cerebral hemorrhage were divided into three groups: the hyperacute group showed a low transfer pattern; the acute group presented inhomogeneous high transfer rates; and the subacute group showed remarkably low transfer rates. In the acute and subacute ischemic stages, increased macromolecules caused higher MTRs than in the chronic stage. In hemorrhagic groups, low MTRs in subacute hemorrhage reflected the transfer of methemoglobin. High MTRs in acute hemorrhage with rich deoxyhemoglobin suggested increased fibrin, plasma, and serum components of macromolecules. The MTC method provided new chronological information on cerebral hemorrhage, adding to that provided by routine MR images. (author)

  2. Determining the chemical exchange saturation transfer (CEST) behavior of citrate and spermine under in vivo conditions

    Science.gov (United States)

    Basharat, Meer; deSouza, Nandita M.; Parkes, Harold G.

    2015-01-01

    Purpose To estimate the exchange rates of labile 1H in citrate and spermine, metabolites present in prostatic secretions, to predict the size of the citrate and spermine CEST effects in vivo. Methods CEST z‐spectra were acquired at high‐field [11.7 Tesla (T)] from citrate and spermine solutions at physiological pH (6.5) using saturation power 6 μT. CEST was performed at different temperatures to determine exchange regimes (slow, intermediate or fast). For low pH solutions of spermine, exchange rates were estimated from resonance line width, fitting z‐spectra using the Bloch equations incorporating exchange, and using quantifying exchange using saturation time experiments (QUEST). These rates were extrapolated to physiological pH. Results Citrate showed little CEST effect at pH 6.5 and temperature (T) = 310 K (maximum 0.001% mM‐1), indicating fast exchange, whereas spermine showed greater CEST effects (maximum 0.2% mM‐1) indicating intermediate‐to‐fast exchange. Extrapolating data acquired from low pH spermine solutions predicts exchange rates at pH 6.5 and T of 310 K of at least 2 × 104s‐1. Conclusion Citrate and spermine show minimal CEST effects at 11.7T even using high saturation power. These effects would be much less than 2% at clinical field‐strengths due to relatively faster exchange and would be masked by CEST from proteins. Magn Reson Med 76:742–746, 2016. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. PMID:26467055

  3. Calcium phosphate saturation in seawater around the Andaman Island

    Digital Repository Service at National Institute of Oceanography (India)

    Naik, S.; Reddy, C.V.G.

    Ionic product (IP) of calcium phosphate is calculated at some stations around Andaman Island. The depthwise variations of the ionic product of calcium phosphate seem to follow a normal trend with maximum saturation value between 100 to 200 m. Using...

  4. Investigation of saturation effects in ceramic phosphors for laser lighting

    DEFF Research Database (Denmark)

    Krasnoshchoka, Anastasiia; Thorseth, Anders; Dam-Hansen, Carsten

    2017-01-01

    We report observation of saturation effects in a Ce:LuAG and Eu-doped nitride ceramic phosphor for conversion of blue laser light for white light generation. The luminous flux from the phosphors material increases linearly with the input power until saturation effects limit the conversion....... It is shown, that the temperature of the phosphor layer influences the saturation power level and the conversion efficiency. It is also shown that the correlated color temperature (CCT), phosphor conversion efficiency and color rendering index (CRI) are dependent both on incident power and spot size diameter...... of the illumination. A phosphor conversion efficiency up to 140.8 lm/W with CRI of 89.4 was achieved. The saturation in a ceramic phosphor, when illuminated by high intensity laser diodes, is estimated to play the main role in limiting the available luminance from laser based lighting systems....

  5. Saturation volume changes and resistivity changes in nickel

    International Nuclear Information System (INIS)

    Birtcher, R.C.; Blewitt, T.H.

    1976-01-01

    Saturation defect concentrations generated by thermal neutron irradiation of 235 U doped nickel at liquid helium temperature were measured by changes in electrical resistivity and volume. The experimental procedure is described

  6. A Partially Saturated Constitutive Theory for Compacted Fills

    National Research Council Canada - National Science Library

    Berney, Ernest

    2004-01-01

    ... variables present within the soil. From a thermodynamic viewpoint, a partially saturated soil can be best described by the free energy associated with each component of the soil and water mixture...

  7. Rib fracture in Prognathodon saturator (Mosasauridae, Late Cretaceous)

    NARCIS (Netherlands)

    Schulp, Anne S.; Walenkamp, G. H I M; Hofman, P.A.M.; Rothschild, B. M.; Jagt, J. W M

    2004-01-01

    Two unusual bumps occur on the internal surface of a rib of the marine reptile Prognathodon saturator from the Upper Cretaceous (Maastrichtian) of Maastricht, The Netherlands. These bumps are interpreted as stress fractures, possibly related to agonistic behaviour.

  8. Virus movement in soil during saturated and unsaturated flow.

    Science.gov (United States)

    Lance, J C; Gerba, C P

    1984-02-01

    Virus movement in soil during saturated and unsaturated flow was compared by adding poliovirus to sewage water and applying the water at different rates to a 250-cm-long soil column equipped with ceramic samplers at different depths. Movement of viruses during unsaturated flow of sewage through soil columns was much less than during saturated flow. Viruses did not move below the 40-cm level when sewage water was applied at less than the maximum infiltration rate; virus penetration in columns flooded with sewage was at least 160 cm. Therefore, virus movement in soils irrigated with sewage should be less than in flooded groundwater recharge basins or in saturated soil columns. Management of land treatment systems to provide unsaturated flow through the soil should minimize the depth of virus penetration. Differences in virus movement during saturated and unsaturated flow must be considered in the development of any model used to simulate virus movement in soils.

  9. Retinal oxygen saturation before and after glaucoma surgery.

    Science.gov (United States)

    Nitta, Eri; Hirooka, Kazuyuki; Shimazaki, Takeru; Sato, Shino; Ukegawa, Kaori; Nakano, Yuki; Tsujikawa, Akitaka

    2017-08-01

    This study compared retinal vessel oxygen saturation before and after glaucoma surgery. Retinal oxygen saturation in glaucoma patients was measured using a non-invasive spectrophotometric retinal oximeter. Adequate image quality was found in 49 of the 108 consecutive glaucoma patients recruited, with 30 undergoing trabeculectomy, 11 EX-PRESS and eight trabeculotomy. Retinal oxygen saturation measurements in the retinal arterioles and venules were performed at 1 day prior to and at approximately 10 days after surgery. Statistical analysis was performed using a Student's t-test. After glaucoma surgery, intraocular pressure (IOP) decreased from 19.8 ± 7.7 mmHg to 9.0 ± 5.7 mmHg (p glaucoma surgery had an effect on the retinal venous oxygen saturation. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  10. Delayed system control in presence of actuator saturation

    Directory of Open Access Journals (Sweden)

    A. Mahjoub

    2014-09-01

    Full Text Available The paper is introducing a new design method for systems’ controllers with input delay and actuator saturations and focuses on how to force the system output to track a reference input not necessarily saturation-compatible. We propose a new norm based on the way we quantify tracking performance as a function of saturation errors found using the same norm. The newly defined norm is related to signal average power making possible to account for most common reference signals e.g. step, periodic. It is formally shown that, whatever the reference shape and amplitude, the achievable tracking quality is determined by a well defined reference tracking mismatch error. This latter depends on the reference rate and its compatibility with the actuator saturation constraint. In fact, asymptotic output-reference tracking is achieved in the presence of constraint-compatible step-like references.

  11. Effects of Contrast Agent and Outer Volume Saturation Bands on Water Suppression and Shimming of Hepatic Single-Volume Proton MR Spectroscopy at 3.0T

    Directory of Open Access Journals (Sweden)

    Li Xu

    2012-01-01

    Full Text Available Purpose. To determine whether administration of gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA and whether placement of the outer volume saturation bands significantly affect shimming and water suppression on hepatic MR spectroscopic prescanning. Method. Region of interest (ROI of 2 cm × 2 cm × 2 cm was carefully positioned in the region of the middle portion of the right hepatic lobe. 32 patients were examined before and after administration of Gd-DTPA with and without outer-volume saturation bands. Linewidths (Full-Width Half-Maximum (FWHM and water suppression were obtained. A paired t-test for comparison of means was used. Results. (1 The group with the outer volume saturation bands demonstrated slightly better water suppression effect than the group without outer volume saturation bands before administration. (2 The group with the outer volume saturation bands demonstrated better water suppression effect than the group without outer volume saturation bands after administration. (3 Both shimming and water suppression effectswere decreased on enhanced MR spectroscopic prescanning (all P<0.05. Conclusions. Placement of the outer volume saturation bands is helpful to improve water suppression both before and after contrast agent administration. Gd-DTPA exerts a slightly adverse effect (a statistically significant but clinically unimportant on magnetic resonance spectroscopic prescanning at 3T.

  12. The history of magnetization process influence on FMR response of particle systems

    International Nuclear Information System (INIS)

    Dumitru, Ioan; Stancu, Alexandru

    2007-01-01

    In order to express the history of magnetization process dependence on ferromagnetic resonance (FMR) for a particle system we use a statistical model based on the Preisach model. The precedent magnetization processes define in Preisach plane a configuration of particle magnetization orientations. The particles are considered single domain and saturated and are modeled as Stoner-Wohlfarth particles. The FMR response of the system is computed by summarizing the individual dynamic susceptibility of the particles, keeping account of the initial directions of the particle magnetizations. The FMR spectra of the particle system is determined considering three initial magnetization states: the demagnetized state, the positive saturated state in which all the particles have the magnetization in the static field direction and the negative saturated state when all the particles have the magnetization in the opposite field direction. The static field dependence of the resonance frequency and linewidth are determined as functions of the initial magnetization states

  13. Renal vein oxygen saturation in renal artery stenosis

    DEFF Research Database (Denmark)

    Nielsen, K; Rehling, M; Henriksen, Jens Henrik Sahl

    1992-01-01

    Renal vein oxygen-saturation was measured in 56 patients with arterial hypertension and unilateral stenosis or occlusion of the renal artery. Oxygen-saturation in blood from the ischaemic kidney (84.4%, range 73-93%) was significantly higher than that from the 'normal' contralateral kidney (81...... than its blood flow. This is probably due to decreased filtration fraction and filtered sodium with subsequent reduction in absolute tubular re-absorption of sodium ions....

  14. Succinct synthesis of saturated hydroxy fatty acids and

    DEFF Research Database (Denmark)

    Kaspersen, Mads Holmgaard; Jenkins, Laura; Dunlop, Julia

    2017-01-01

    Saturated hydroxy fatty acids make up a class of underexplored lipids with potentially interesting biological activities. We report a succinct and general synthetic route to saturated hydroxy fatty acids hydroxylated at position 6 or higher, and exemplify this with the synthesis of hydroxylauric ...... acids. All regioisomers of hydroxylauric acids were tested on free fatty acid receptors FFA1, FFA4 and GPR84. The results show that the introduction of a hydroxy group and its position have a high impact on receptor activity....

  15. Pulse Distortion in Saturated Fiber Optical Parametric Chirped Pulse Amplification

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh; Da Ros, Francesco; Rottwitt, Karsten

    2012-01-01

    Fiber optical parametric chirped pulse amplification is experimentally compared for different chirped pulses in the picosecond regime. The amplified chirped pulses show distortion appearing as pedestals after recompression when the amplifier is operated in saturation.......Fiber optical parametric chirped pulse amplification is experimentally compared for different chirped pulses in the picosecond regime. The amplified chirped pulses show distortion appearing as pedestals after recompression when the amplifier is operated in saturation....

  16. Facile and Green Synthesis of Saturated Cyclic Amines

    Directory of Open Access Journals (Sweden)

    Arruje Hameed

    2017-10-01

    Full Text Available Single-nitrogen containing saturated cyclic amines are an important part of both natural and synthetic bioactive compounds. A number of methodologies have been developed for the synthesis of aziridines, azetidines, pyrrolidines, piperidines, azepanes and azocanes. This review highlights some facile and green synthetic routes for the synthesis of unsubstituted, multisubstituted and highly functionalized saturated cyclic amines including one-pot, microwave assisted, metal-free, solvent-free and in aqueous media.

  17. Law of nonlinear flow in saturated clays and radial consolidation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    It was derived that micro-scale amount level of average pore radius of clay changed from 0.01 to 0.1 micron by an equivalent concept of flow in porous media. There is good agreement between the derived results and test ones. Results of experiments show that flow in micro-scale pore of saturated clays follows law of nonlinear flow. Theoretical analyses demonstrate that an interaction of solid-liquid interfaces varies inversely with permeability or porous radius. The interaction is an important reason why nonlinear flow in saturated clays occurs. An exact mathematical model was presented for nonlinear flow in micro-scale pore of saturated clays. Dimension and physical meanings of parameters of it are definite. A new law of nonlinear flow in saturated clays was established. It can describe characteristics of flow curve of the whole process of the nonlinear flow from low hydraulic gradient to high one. Darcy law is a special case of the new law. A mathematical model was presented for consolidation of nonlinear flow in radius direction in saturated clays with constant rate based on the new law of nonlinear flow. Equations of average mass conservation and moving boundary, and formula of excess pore pressure distribution and average degree of consolidation for nonlinear flow in saturated clay were derived by using an idea of viscous boundary layer, a method of steady state in stead of transient state and a method of integral of an equation. Laws of excess pore pressure distribution and changes of average degree of consolidation with time were obtained. Results show that velocity of moving boundary decreases because of the nonlinear flow in saturated clay. The results can provide geology engineering and geotechnical engineering of saturated clay with new scientific bases. Calculations of average degree of consolidation of the Darcy flow are a special case of that of the nonlinear flow.

  18. Noise and saturation properties of semiconductor quantum dot optical amplifiers

    DEFF Research Database (Denmark)

    Berg, Tommy Winther; Mørk, Jesper

    2002-01-01

    We present a detailed theoretical analysis of quantum dot optical amplifiers. Due to the presence of a reservoir of wetting layer states, the saturation and noise properties differ markedly from bulk or QW amplifiers and may be significantly improved.......We present a detailed theoretical analysis of quantum dot optical amplifiers. Due to the presence of a reservoir of wetting layer states, the saturation and noise properties differ markedly from bulk or QW amplifiers and may be significantly improved....

  19. Nonlinear Gain Saturation in Active Slow Light Photonic Crystal Waveguides

    DEFF Research Database (Denmark)

    Chen, Yaohui; Mørk, Jesper

    2013-01-01

    We present a quantitative three-dimensional analysis of slow-light enhanced traveling wave amplification in an active semiconductor photonic crystal waveguides. The impact of slow-light propagation on the nonlinear gain saturation of the device is investigated.......We present a quantitative three-dimensional analysis of slow-light enhanced traveling wave amplification in an active semiconductor photonic crystal waveguides. The impact of slow-light propagation on the nonlinear gain saturation of the device is investigated....

  20. Magnetic field and magnetic isotope effects on photochemical reactions

    International Nuclear Information System (INIS)

    Wakasa, Masanobu

    1999-01-01

    By at present exact experiments and the theoretical analysis, it was clear that the magnetic field less than 2 T affected a radical pair reaction and biradical reaction. The radical pair life and the dissipative radical yield showed the magnetic field effects on chemical reactions. The radical pair mechanism and the triplet mechanism were known as the mechanism of magnetic field effects. The radical pair mechanism consists of four mechanisms such as the homogeneous hyperfine interaction (HFC), the delta-g mechanism, the relaxation mechanism and the level cross mechanism. In order to observe the magnetic effects of the radical pair mechanism, two conditions need, namely, the recombination rate of singlet radical pair > the dissipation rate and the spin exchange rate > the dissipation rate. A nanosecond laser photo-decomposition equipment can observe the magnetic field effects. The inversion phenomena of magnetic field effect, isolation of the relaxation mechanism and the delta-g mechanism, the magnetic field effect of heavy metal radical reaction, the magnetic field effect in homogeneous solvent, saturation of delta-g mechanism are explained. The succeeded examples of isotope concentration by the magnetic isotope effect are 17 O, 19 Si, 33 S, 73 Ge and 235 U. (S.Y.)

  1. Magnetostriction in glass-coated magnetic microwires

    International Nuclear Information System (INIS)

    Zhukov, A.; Zhukova, V.; Blanco, J.M.; Cobeno, A.F.; Vazquez, M.; Gonzalez, J

    2003-01-01

    The hysteretic magnetic properties of glass coated magnetic microwires depend on the magnetostriction constant: Co-rich microwires with negative magnetostriction constant present an almost non-hysteretic loop with relatively high magnetic anisotropy field up to around 8 kA/m. In contrast, Fe-rich microwires with positive magnetostriction show rectangular hysteresis loops with switching field depending on diameter of the metallic nucleus and the thickness of the glass coating. The softest magnetic properties, such as large magnetic permeability, are observed in nearly zero magnetostrictive alloys. It is then obvious that the experimental determination of the saturation magnetostriction λ s of glass-coated microwires is very important to predict their magnetic behaviour. Different methods for the determination of the saturation magnetostriction λ s of tiny glass coated microwires have been reviewed and compared in this manuscript. Small angle magnetization rotation (SAMR) method and change of the giant magneto-impedance spectrum under applied stress have been employed in nearly zero magnetostrictive in as-prepared and current annealed glass-covered microwires. The conditions of applicability of these methods to the microwires have been analysed, taking into account the domain structure expected for vanishing magnetostriction constant of the metallic nucleus. These different techniques give similar saturation magnetostriction constant values. Heat treatment results in a significant change of λ s

  2. Rapid determination of oxygen saturation and vascularity for cancer detection.

    Directory of Open Access Journals (Sweden)

    Fangyao Hu

    Full Text Available A rapid heuristic ratiometric analysis for estimating tissue hemoglobin concentration and oxygen saturation from measured tissue diffuse reflectance spectra is presented. The analysis was validated in tissue-mimicking phantoms and applied to clinical measurements in head and neck, cervical and breast tissues. The analysis works in two steps. First, a linear equation that translates the ratio of the diffuse reflectance at 584 nm and 545 nm to estimate the tissue hemoglobin concentration using a Monte Carlo-based lookup table was developed. This equation is independent of tissue scattering and oxygen saturation. Second, the oxygen saturation was estimated using non-linear logistic equations that translate the ratio of the diffuse reflectance spectra at 539 nm to 545 nm into the tissue oxygen saturation. Correlations coefficients of 0.89 (0.86, 0.77 (0.71 and 0.69 (0.43 were obtained for the tissue hemoglobin concentration (oxygen saturation values extracted using the full spectral Monte Carlo and the ratiometric analysis, for clinical measurements in head and neck, breast and cervical tissues, respectively. The ratiometric analysis was more than 4000 times faster than the inverse Monte Carlo analysis for estimating tissue hemoglobin concentration and oxygen saturation in simulated phantom experiments. In addition, the discriminatory power of the two analyses was similar. These results show the potential of such empirical tools to rapidly estimate tissue hemoglobin in real-time spectral imaging applications.

  3. Diffuse reflectance spectroscopy for the measurement of tissue oxygen saturation

    International Nuclear Information System (INIS)

    Sircan-Kucuksayan, A; Canpolat, M; Uyuklu, M

    2015-01-01

    Tissue oxygen saturation (StO 2 ) is a useful parameter for medical applications. A spectroscopic method has been developed to detect pathologic tissues, due to a lack of normal blood circulation, by measuring StO 2 . In this study, human blood samples with different levels of oxygen saturation have been prepared and spectra were acquired using an optical fiber probe to investigate the correlation between the oxygen saturation levels and the spectra. A linear correlation between the oxygen saturation and ratio of the intensities (760 nm to 790 nm) of the spectra acquired from blood samples has been found. In a validation study, oxygen saturations of the blood samples were estimated from the spectroscopic measurements with an error of 2.9%. It has also been shown that the linear dependence between the ratio and the oxygen saturation of the blood samples was valid for the blood samples with different hematocrits. Spectra were acquired from the forearms of 30 healthy volunteers to estimate StO 2 prior to, at the beginning of, after 2 min, and at the release of total vascular occlusion. The average StO 2 of a forearm before and after the two minutes occlusion was significantly different. The results suggested that optical reflectance spectroscopy is a sensitive method to estimate the StO 2 levels of human tissue. The technique developed to measure StO 2 has potential to detect ischemia in real time. (paper)

  4. The relation between oxygen saturation level and retionopathy of prematurity

    Directory of Open Access Journals (Sweden)

    Mohammad Gharavi Fard

    2016-03-01

    Full Text Available Introduction: Oxygen therapy used for preterm infant disease might be associated with oxygen toxicity or oxidative stress. The exact oxygen concentration to control and maintain the arterial oxygen saturation balance is not certainly clear. We aimed to compare the efficacy of higher or lower oxygen saturations on the development of severe retinopathy of prematurity which is a major cause of blindness in preterm neonates. Methods: PubMed was searched for obtaining the relevant articles. A total of seven articles were included after studying the titles, abstracts, and the full text of retrieved articles at initial search. Inclusion criteria were all the English language human clinical randomized controlled trials with no time limitation, which studied the efficacy of low versus high oxygen saturation measured by pulse oximetry in preterm infants.Result: It can be suggested that lower limits of oxygen saturations have higher efficacy at postmesetural age of ≤28 weeks in preterm neonates. This relation has been demonstrated in five large clinical trials including three Boost trials, COT, and Support.Discussion: Applying higher concentrations of oxygen supplementations at mesentural age ≥32 weeks reduced the development of retinopathy of prematurity. Lower concentrations of oxygen saturation decreased the incidence and the development of retinopathy of prematurity in preterm neonates while applied soon after the birth.Conclusions: Targeting levels of oxygen saturation in the low or high range should be performed cautiously with attention to the postmesentural age in preterm infants at the time of starting the procedures.

  5. Calculation of persistent currents in superconducting magnets

    Directory of Open Access Journals (Sweden)

    C. Völlinger

    2000-12-01

    Full Text Available This paper describes a semianalytical hysteresis model for hard superconductors. The model is based on the critical state model considering the dependency of the critical current density on the varying local field in the superconducting filaments. By combining this hysteresis model with numerical field computation methods, it is possible to calculate the persistent current multipole errors in the magnet taking local saturation effects in the magnetic iron parts into consideration. As an application of the method, the use of soft magnetic iron sheets (coil protection sheets mounted between the coils and the collars for partial compensation of the multipole errors during the ramping of the magnets is investigated.

  6. Method for the detection of a magnetic field utilizing a magnetic vortex

    Science.gov (United States)

    Novosad, Valentyn [Chicago, IL; Buchanan, Kristen [Batavia, IL

    2010-04-13

    The determination of the strength of an in-plane magnetic field utilizing one or more magnetically-soft, ferromagnetic member, having a shape, size and material whereas a single magnetic vortex is formed at remanence in each ferromagnetic member. The preferred shape is a thin circle, or dot. Multiple ferromagnetic members can also be stacked on-top of each other and separated by a non-magnetic spacer. The resulting sensor is hysteresis free. The sensor's sensitivity, and magnetic saturation characteristics may be easily tuned by simply altering the material, size, shape, or a combination thereof to match the desired sensitivity and saturation characteristics. The sensor is self-resetting at remanence and therefore does not require any pinning techniques.

  7. The role of cobalt ferrite magnetic nanoparticles in medical science

    International Nuclear Information System (INIS)

    Amiri, S.; Shokrollahi, H.

    2013-01-01

    The nanotechnology industry is rapidly growing and promises that the substantial changes that will have significant economic and scientific impacts be applicable to a wide range of areas, such as aerospace engineering, nano-electronics, environmental remediation and medical healthcare. In this area, cobalt ferrite nanoparticles have been regarded as one of the competitive candidates because of their suitable physical, chemical and magnetic properties like the high anisotropy constant, high coercivity and high Curie temperature, moderate saturation magnetization and ease of synthesis. This paper introduces the magnetic properties, synthesis methods and some medical applications, including the hyperthermia, magnetic resonance imaging (MRI), magnetic separation and drug delivery of cobalt ferrite nanoparticles. Highlights: ► Cobalt ferrite nanoparticles are one of the most important materials for nanomedicine. ► They have high coercivity and moderate saturation magnetization. ► Cobalt ferrite nanoparticles are synthesized easily. ► They are a good candidate for hyperthermia and magnetic resonance imaging.

  8. On the water saturation calculation in hydrocarbon sandstone reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Stalheim, Stein Ottar

    2002-07-01

    The main goal of this work was to identify the most important uncertainty sources in water saturation calculation and examine the possibility for developing new S{sub w} - equations or possibility to develop methods to remove weaknesses and uncertainties in existing S{sub w} - equations. Due to the need for industrial applicability of the equations we aimed for results with the following properties: The accuracy in S{sub w} should increase compared with existing S{sub w} - equations. The equations should be simple to use in petrophysical evaluations. The equations should be based on conventional logs and use as few as possible input parameters. The equations should be numerical stable. This thesis includes an uncertainty and sensitivity analysis of the most common S{sub w} equations. The results are addressed in chapter 3 and were intended to find the most important uncertainty sources in water saturation calculation. To increase the knowledge of the relationship between R{sub t} and S{sub w} in hydrocarbon sandstone reservoirs and to understand how the pore geometry affects the conductivity (n and m) of the rock a theoretical study was done. It was also an aim to examine the possibility for developing new S{sub w} - equations (or investigation an effective medium model) valid inhydrocarbon sandstone reservoirs. The results are presented in paper 1. A new equation for water saturation calculation in clean sandstone oil reservoirs is addressed in paper 2. A recommendation for best practice of water saturation calculation in non water wet formation is addressed in paper 3. Finally a new equation for water saturation calculation in thinly interbedded sandstone/mudstone reservoirs is presented in paper 4. The papers are titled: 1) Is the saturation exponent n a constant. 2) A New Model for Calculating Water Saturation In 3) Influence of wettability on water saturation modeling. 4) Water Saturation Calculations in Thinly Interbedded Sandstone/mudstone Reservoirs. A

  9. Specialty magnets

    International Nuclear Information System (INIS)

    Halbach, K.

    1986-07-01

    A number of basic conceptual designs are explained for magnet systems that use permanent magnet materials. Included are iron free multipoles and hybrid magnets. Also appended is a discussion of the manufacturing process and magnetic properties of some permanent magnet materials

  10. Magnetic Materials: Novel Monitors of Long-Term Evolution of Engineered Barrier Systems

    Directory of Open Access Journals (Sweden)

    Simon L. Harley

    2016-12-01

    Full Text Available Most safety cases for the deep geological disposal of radioactive waste are reliant on the swelling of bentonite in the engineered barrier system as it saturates with groundwater. Assurance of safety therefore requires effective monitoring of bentonite saturation. The time- and fluid-dependent corrosion of synthetic magnets embedded in bentonite is demonstrated here to provide a novel and passive means of monitoring saturation. Experiments have been conducted at 70 °C in which neo magnets, AlNiCo magnets, and ferrite magnets have been reacted with saline (NaCl, KCl, CaCl2 solutions and alkaline fluids (NaOH, KOH, Ca(OH2 solutions; pH = 12 in the presence of bentonite. Nd-Fe-B magnets undergo extensive corrosion that results in a dramatic change from ferromagnetic to superparamagnetic behaviour concomitant with bentonite saturation. AlNiCo magnets in saline solutions show corrosion but only limited decreases in their magnetic intensities, and ferrite magnets are essentially unreactive on the experimental timescales, retaining their initial magnetic properties. For all magnets the impact of their corrosion on bentonite swelling is negligible; alteration of bentonite is essentially governed by the applied fluid composition. In principle, synthetic magnet arrays can, with further development, be designed and embedded in bentonite to monitor its fluid saturation without compromising the integrity of the engineered barrier system itself.

  11. 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.

  12. Thermally activated magnetization reversal in magnetic tunnel junctions

    International Nuclear Information System (INIS)

    Guang-Hong, Zhou; Yin-Gang, Wang; Xian-Jin, Qi; Zi-Quan, Li; Jian-Kang, Chen

    2009-01-01

    In this paper, the magnetization reversal of the ferromagnetic layers in the IrMn/CoFe/AlO x /CoFe magnetic tunnel junction has been investigated using bulk magnetometry. The films exhibit very complex magnetization processes and reversal mechanism. Thermal activation phenomena such as the training effect, the asymmetry of reversal, the loop broadening and the decrease of exchange field while holding the film at negative saturation have been observed on the hysteresis loops of the pinned ferromagnetic layer while not on those of the free ferromagnetic layer. The thermal activation phenomena observed can be explained by the model of two energy barrier distributions with different time constants. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  13. Tuning microstructure and magnetic properties of electrodeposited CoNiP films by high magnetic field annealing

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Chun; Wang, Kai [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Li, Donggang, E-mail: lidonggang@smm.neu.edu.cn [School of Metallurgy, Northeastern University, Shenyang 110819 (China); Lou, Changsheng [School of Materials Science and Engineering, Shenyang Ligong University, Shenyang 110159 (China); Zhao, Yue; Gao, Yang [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Wang, Qiang, E-mail: wangq@mail.neu.edu.cn [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China)

    2016-10-15

    A high magnetic field (up to 12 T) has been used to anneal 2.6-µm-thick Co{sub 50}Ni{sub 40}P{sub 10} films formed by pulse electrodeposition. The effects of high magnetic field annealing on the microstructure and magnetic properties of CoNiP thin films have been investigated. It was found that a high magnetic field accelerated a phase transformation from fcc to hcp and enhanced the preferred hcp-(002) orientation during annealing. Compared with the films annealed without a magnetic field, annealing at 12 T decreased the surface particle size, roughness, and coercivity, but increased the saturation magnetization and remanent magnetization of CoNiP films. The out-of-plane coercivity was higher than that the in-plane for the as-deposited films. After annealing without a magnetic field, the out-of-plane coercivity was equal to that of the in-plane. However, the out-of-plane coercivity was higher than that of the in-plane when annealing at 12 T. These results indicate that high magnetic field annealing is an effective method for tuning the microstructure and magnetic properties of thin films. - Highlights: • High magnetic field annealing accelerated phase transformation from γ to ε. • High magnetic field annealing enhanced preferred hcp-(002) orientation. • High magnetic field annealing decreased particle size, roughness and coercivity. • High magnetic field annealing increased the saturation and remanent magnetization.

  14. Influence of interdiffusion on the magnetic properties of Co/Si (100) films after high magnetic field annealing

    International Nuclear Information System (INIS)

    Zhao, Yue; Wang, Kai; Wang, Qiang; Li, Guojian; Lou, Changsheng; Pang, Hongxuan; He, Jicheng

    2015-01-01

    The influence of interdiffusion on the magnetic properties of Co/Si (100) films after thermal annealing in the presence of a strong magnetic field was investigated. The interdiffusion coefficients of films that were annealed at temperatures of 380 °C and 420 °C in the presence of high magnetic fields were not affected. However, the interdiffusion coefficient of films annealed at 400 °C in the presence of a high magnetic field decreased significantly. The change in the interdiffusion coefficient, caused by high magnetic field annealing, increased the content of the magnetic phase. This increase in the magnetic phase improved the saturation magnetization. A new method of high magnetic field annealing is presented that can modulate the diffusion and magnetic properties of thin films. - Highlights: • Interdiffusion of Co/Si (100) films by high magnetic field annealing was studied. • Thickness of the diffusion layer was reduced by magnetic field annealing at 400 °C. • Interdiffusion coefficient decreased following magnetic field annealing at 400 °C. • Saturation magnetization increased after high magnetic field annealing at 400 °C

  15. Molybdenite saturation in silicic magmas: Occurrence and petrological implications

    Science.gov (United States)

    Audetat, A.; Dolejs, D.; Lowenstern, J. B.

    2011-01-01

    We identified molybdenite (MoS2) as an accessory magmatic phase in 13 out of 27 felsic magma systems examined worldwide. The molybdenite occurs as small (molybdenite-saturated samples reveal 1-13 ppm Mo in the melt and geochemical signatures that imply a strong link to continental rift basalt-rhyolite associations. In contrast, arc-associated rhyolites are rarely molybdenite-saturated, despite similar Mo concentrations. This systematic dependence on tectonic setting seems to reflect the higher oxidation state of arc magmas compared with within-plate magmas. A thermodynamic model devised to investigate the effects of T, f O2 and f S2 on molybdenite solubility reliably predicts measured Mo concentrations in molybdenite-saturated samples if the magmas are assumed to have been saturated also in pyrrhotite. Whereas pyrrhotite microphenocrysts have been observed in some of these samples, they have not been observed from other molybdenite-bearing magmas. Based on the strong influence of f S2 on molybdenite solubility we calculate that also these latter magmas must have been at (or very close to) pyrrhotite saturation. In this case the Mo concentration of molybdenite-saturated melts can be used to constrain both magmatic f O2 and f S2 if temperature is known independently (e.g. by zircon saturation thermometry). Our model thus permits evaluation of magmatic f S2, which is an important variable but is difficult to estimate otherwise, particularly in slowly cooled rocks. ?? The Author 2011. Published by Oxford University Press. All rights reserved.

  16. Bifurcation Phenomena of a Magnetic Island at a Rational Surface in a Magnetic-Shear Control Experiment

    International Nuclear Information System (INIS)

    Ida, K.; Inagaki, S.; Yoshinuma, M.; Narushima, Y.; Itoh, K.; Kobuchi, T.; Watanabe, K. Y.; Funaba, H.; Sakakibara, S.; Morisaki, T.; LHD Experimental Group

    2008-01-01

    Three states of a magnetic island are observed when the magnetic shear at the rational surface is modified using inductive current associated with the neutral beam current drive in the Large Helical Device. One state is the healed magnetic island with a zero island width. The second state is the saturated magnetic island with partial flattening of the T e profile. The third state is characterized by the global flattening of the T e profile in the core region. As the plasma assumes each of the three states consecutively through a bifurcation process a clear hysteresis in the relation between the size of the magnetic island and the magnetic shear is observed

  17. Repulsion-based model for contact angle saturation in electrowetting.

    Science.gov (United States)

    Ali, Hassan Abdelmoumen Abdellah; Mohamed, Hany Ahmed; Abdelgawad, Mohamed

    2015-01-01

    We introduce a new model for contact angle saturation phenomenon in electrowetting on dielectric systems. This new model attributes contact angle saturation to repulsion between trapped charges on the cap and base surfaces of the droplet in the vicinity of the three-phase contact line, which prevents these surfaces from converging during contact angle reduction. This repulsion-based saturation is similar to repulsion between charges accumulated on the surfaces of conducting droplets which causes the well known Coulombic fission and Taylor cone formation phenomena. In our model, both the droplet and dielectric coating were treated as lossy dielectric media (i.e., having finite electrical conductivities and permittivities) contrary to the more common assumption of a perfectly conducting droplet and perfectly insulating dielectric. We used theoretical analysis and numerical simulations to find actual charge distribution on droplet surface, calculate repulsion energy, and minimize energy of the total system as a function of droplet contact angle. Resulting saturation curves were in good agreement with previously reported experimental results. We used this proposed model to predict effect of changing liquid properties, such as electrical conductivity, and system parameters, such as thickness of the dielectric layer, on the saturation angle, which also matched experimental results.

  18. Description of saturation curves and boiling process of dry air

    Directory of Open Access Journals (Sweden)

    Vestfálová Magda

    2018-01-01

    Full Text Available Air is a mixture of gases forming the gas wrap of Earth. It is formed by dry air, moisture and other pollutants. Dry air is a substance whose thermodynamic properties in gaseous state, as well as the thermodynamic properties of its main constituents in gaseous state, are generally known and described in detail in the literature. The liquid air is a bluish liquid and is industrially used to produce oxygen, nitrogen, argon and helium by distillation. The transition between the gaseous and liquid state (the condensation process, resp. boiling process, is usually displayed in the basic thermodynamic diagrams using the saturation curves. The saturation curves of all pure substances are of a similar shape. However, since the dry air is a mixture, the shapes of its saturation curves are modified relative to the shapes corresponding to the pure substances. This paper deals with the description of the dry air saturation curves as a mixture, i.e. with a description of the process of phase change of dry air (boiling process. The dry air saturation curves are constructed in the basic thermodynamic charts based on the values obtained from the literature. On the basis of diagrams, data appearing in various publications are interpreted and put into context with boiling process of dry air.

  19. Gaseous saturable absorbers for the Helios CO2 laser system

    International Nuclear Information System (INIS)

    Haglund, R.F. Jr.; Nowak, A.V.; Czuchlewski, S.J.

    1981-01-01

    Saturable absorbers are widely used to suppress parasitic oscillations in large-aperture, high-power CO 2 fusion-laser systems. We report experimental results on SF 6 -based gaseous saturable absorbers used for parasitic suppression in the eight-beam, 10 kJ Helios fusion-laser system. The gas mix effectively quenches self-lasing in the 9 and 10 μm branches of the CO 2 laser spectrum while simultaneously allowing high transmission of subnanosecond multiwavelength pulses for target-irradiation experiments. The gas isolator now in use consists of SF 6 and the additional fluorocarbons: 1, 1-difluoroethane (FC-152a); dichlorodifluoromethane (FC-12); chloropentafluoroethane (FC-115); 1,1-dichloro 2,2-difluoroethylene (FC-1112a); chlorotrifluoroethylene (FC-1113); and perfluorocyclobutane (FC-C318). The saturation of the mix was studied as a function of incident fluence, pressure, cell length, and incident wavelength. Experimental results are presented on the saturation properties of pure SF 6 and FC-152a and compared with the saturation behavior of CO 2 at 400 0 C

  20. THE SEARCH FOR SUPER-SATURATION IN CHROMOSPHERIC EMISSION

    International Nuclear Information System (INIS)

    Christian, Damian J.; Arias, Tersi; Mathioudakis, Mihalis; Jess, David B.; Jardine, Moira

    2011-01-01

    We investigate if the super-saturation phenomenon observed at X-ray wavelengths for the corona exists in the chromosphere for rapidly rotating late-type stars. Moderate resolution optical spectra of fast-rotating EUV- and X-ray-selected late-type stars were obtained. Stars in α Per were observed in the northern hemisphere with the Isaac Newton 2.5 m telescope and Intermediate Dispersion Spectrograph. Selected objects from IC 2391 and IC 2602 were observed in the southern hemisphere with the Blanco 4 m telescope and R-C spectrograph at CTIO. Ca II H and K fluxes were measured for all stars in our sample. We find the saturation level for Ca II K at log (L CaK /L bol ) = -4.08. The Ca II K flux does not show a decrease as a function of increased rotational velocity or smaller Rossby number as observed in the X-ray. This lack of 'super-saturation' supports the idea of coronal stripping as the cause of saturation and super-saturation in stellar chromospheres and coronae, but the detailed underlying mechanism is still under investigation.

  1. Bulk hydrodynamic stability and turbulent saturation in compressing hot spots

    Science.gov (United States)

    Davidovits, Seth; Fisch, Nathaniel J.

    2018-04-01

    For hot spots compressed at constant velocity, we give a hydrodynamic stability criterion that describes the expected energy behavior of non-radial hydrodynamic motion for different classes of trajectories (in ρR — T space). For a given compression velocity, this criterion depends on ρR, T, and d T /d (ρR ) (the trajectory slope) and applies point-wise so that the expected behavior can be determined instantaneously along the trajectory. Among the classes of trajectories are those where the hydromotion is guaranteed to decrease and those where the hydromotion is bounded by a saturated value. We calculate this saturated value and find the compression velocities for which hydromotion may be a substantial fraction of hot-spot energy at burn time. The Lindl (Phys. Plasmas 2, 3933 (1995)] "attractor" trajectory is shown to experience non-radial hydrodynamic energy that grows towards this saturated state. Comparing the saturation value with the available detailed 3D simulation results, we find that the fluctuating velocities in these simulations reach substantial fractions of the saturated value.

  2. Bulk elastic wave propagation in partially saturated porous solids

    International Nuclear Information System (INIS)

    Berryman, J.G.; Thigpen, L.; Chin, R.C.Y.

    1988-01-01

    The linear equations of motion that describe the behavior of small disturbances in a porous solid containing both liquid and gas are solved for bulk wave propagation. The equations have been simplified by neglecting effects due to changes in capillary pressure. With this simplifying assumption, the equations reduce to two coupled (vector) equations of the form found in Biot's equations (for full saturation) but with more complicated coefficients. As in fully saturated solids, two shear waves with the same speed but different polarizations exist as do two compressional waves with distinct speeds. Attenuation effects can be enhanced in the partially saturated solid, depending on the distribution of gas in the pore space. Two models of the liquid/gas spatial distribution are considered: a segregated-fluids model and a mixed-fluids model. The two models predict comparable attentuation when the gas saturation is low, but the segregated-fluids model predicts a more rapid roll-off of attenuation as the gas saturation increases

  3. A new theoretical interpretation of Archie's saturation exponent

    Directory of Open Access Journals (Sweden)

    P. W. J. Glover

    2017-07-01

    Full Text Available This paper describes the extension of the concepts of connectedness and conservation of connectedness that underlie the generalized Archie's law for n phases to the interpretation of the saturation exponent. It is shown that the saturation exponent as defined originally by Archie arises naturally from the generalized Archie's law. In the generalized Archie's law the saturation exponent of any given phase can be thought of as formally the same as the phase (i.e. cementation exponent, but with respect to a reference subset of phases in a larger n-phase medium. Furthermore, the connectedness of each of the phases occupying a reference subset of an n-phase medium can be related to the connectedness of the subset itself by Gi = GrefSini. This leads naturally to the idea of the term Sini for each phase i being a fractional connectedness, where the fractional connectednesses of any given reference subset sum to unity in the same way that the connectednesses sum to unity for the whole medium. One of the implications of this theory is that the saturation exponent of any phase can be now be interpreted as the rate of change of the fractional connectedness with saturation and connectivity within the reference subset.

  4. Ion-cyclotron instability in magnetic mirrors

    International Nuclear Information System (INIS)

    Pearlstein, L.D.

    1987-01-01

    This report reviews the role of ion-cyclotron frequency instability in magnetic mirrors. The modes discussed here are loss-cone or anisotropy driven. The discussion includes quasilinear theory, explosive instabilities of 3-wave interaction and non-linear Landau damping, and saturation due to non-linear orbits

  5. Effect of hydrophobic coating on the magnetic anisotropy and radiofrequency heating of γ-Fe.sub.2./sub.O.sub.3./sub. nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Singh, M.; Ulbrich, P.; Prokopec, V.; Svoboda, P.; Šantavá, Eva; Štěpánek, F.

    2013-01-01

    Roč. 339, AUG (2013), s. 106-113 ISSN 0304-8853 Institutional support: RVO:68378271 Keywords : nanoparticle * maghemite * blocking temperature * superparamagnetism * saturation magnetization Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.002, year: 2013

  6. Entirely saturated unilateral smear of laser spot in CCD

    International Nuclear Information System (INIS)

    Zhang Zhen; Zhou Menglian; Zhang Jianmin; Lin Xinwei

    2013-01-01

    In the video of linear CCD camera being irradiated by 532 nm CW laser, the entirely saturated unilateral smear of laser spot was found. The smear area does not represent the distribution of laser. Since this smear lies merely in one side of laser spot, it can not be induced by light leaking or carriers blooming, and it may be induced by charge transfer loss. However, the feature that the smear area is entirely saturated can not be explained by the current constant model of charge transfer inefficiency. Based on the inner structure and operating principle of buried channel CCD, a new model of charge transfer inefficiency that varies with charge quantity is proposed, which can explain the entirely saturated unilateral smear of laser spot. (authors)

  7. A new through-tubing oil-saturation measurement system

    International Nuclear Information System (INIS)

    Roscoe, B.A.; Adolph, R.A.; Bontemy, Y.; Cheeseborough, J.C. III; Hall, J.S.; McKeon, D.C.; Pittman, D.; Seeman, B.; Thomas, S.R. Jr.

    1991-01-01

    This paper reports on carbon-oxygen logging which is used primarily to estimate oil saturation in cased-hole conditions when the formation water is fresh or unknown. The drawbacks of current techniques are: slow logging speed, large tool diameter, and excessive sensitivity to borehole fluid composition. A new, slim, neutron-induced gamma ray spectroscopy logging system has been developed to overcome some of these limitations. The new logging service is called the Reservoir Saturation (RST) Tool. Initial field tests are being carried out in the Middle East. The RST tool uses multiple detectors to separate the signal contributions from the borehole and the formation. Therefore, even when the borehole fluid composition is unknown, oil saturation can be determined in addition to the borehole oil fraction. This presents the possibility of logging flowing wells, which ensures that reinvasion and crossflow will not affect the results, and eliminates the costs of well preparation

  8. Correlations for Saturation Efficiency of Evaporative Cooling Pads

    Science.gov (United States)

    Jain, J. K.; Hindoliya, D. A.

    2014-01-01

    This paper presents some experimental investigations to obtain correlations for saturation efficiency of evaporative cooling pads. Two commonly used materials namely aspen and khus fibers along with new materials namely coconut fibers and palash fibers were tested in a laboratory using suitably fabricated test setup. Simple mathematical correlations have been developed for calculating saturation efficiency of evaporating cooling pads which can be used to predict their performance at any desired mass flow rate. Performances of four different pad materials were also compared using developed correlations. An attempt was made to test two new materials (i.e. fibers of palash wood and coconut) to check their suitability as wetted media for evaporative cooling pads. It was found that Palash wood fibers offered highest saturation efficiency compared to that of other existing materials such as aspen and khus fibers at different mass flow rate of air.

  9. Premature saturation in backpropagation networks: Mechanism and necessary conditions

    International Nuclear Information System (INIS)

    Vitela, J.E.; Reifman, J.

    1997-01-01

    The mechanism that gives rise to the phenomenon of premature saturation of the output units of feedforward multilayer neural networks during training with the standard backpropagation algorithm is described. The entire process of premature saturation is characterized by three distinct stages and it is concluded that the momentum term plays the leading role in the occurrence of the phenomenon. The necessary conditions for the occurrence of premature saturation are presented and a new method is proposed, based on these conditions, that eliminates the occurrence of the phenomenon. Validity of the conditions and the proposed method are illustrated through simulation results. Three case studies are presented. The first two came from a training session for classification of three component failures in a nuclear power plant. The last case, comes from a training session for classification of welded fuel elements

  10. Prediction of saturation using the carbon/oxygen log

    Energy Technology Data Exchange (ETDEWEB)

    Horner, S.C.; Sanyal, S.K.

    1984-09-01

    This project investigates the nature of Dresser-Atlas Carbon/Oxygen Log gamma ray spectra. It presents an attempt to improve the signal-to-noise ratio of the C/O and Si/Ca parameters used by Dresser-Atlas to determine oil saturation. Two techniques were developed to subtract the Compton background from the spectral data. Neither technique significantly improves the accuracy of the cased-hole prediction of oil saturation. However, it has been shown that it is possible to develop a satisfactory correlation for oil saturation on a well-by-well basis. This correlation can then be used to generate oil-in-place from the C/O and Si/Ca ratios. 17 references.

  11. Error of image saturation in the structured-light method.

    Science.gov (United States)

    Qi, Zhaoshuai; Wang, Zhao; Huang, Junhui; Xing, Chao; Gao, Jianmin

    2018-01-01

    In the phase-measuring structured-light method, image saturation will induce large phase errors. Usually, by selecting proper system parameters (such as the phase-shift number, exposure time, projection intensity, etc.), the phase error can be reduced. However, due to lack of a complete theory of phase error, there is no rational principle or basis for the selection of the optimal system parameters. For this reason, the phase error due to image saturation is analyzed completely, and the effects of the two main factors, including the phase-shift number and saturation degree, on the phase error are studied in depth. In addition, the selection of optimal system parameters is discussed, including the proper range and the selection principle of the system parameters. The error analysis and the conclusion are verified by simulation and experiment results, and the conclusion can be used for optimal parameter selection in practice.

  12. Amplifying mirrors with saturated gain without and with a resonator

    DEFF Research Database (Denmark)

    Skettrup, Torben

    2007-01-01

    An investigation of amplifying mirrors with a view to their use in resonator structures has been performed. Both non-saturated and saturated amplifying mirrors are demonstrated. It was found that relatively high values of gain (typical 5-10 times) can be obtained even when saturation is taken...... into account. Several resonator structures containing from two up to four mirrors, some including beamsplitters, are investigated. It was found that the gain to a first approximation depends only on the ratio between the pumping power and the input power on the amplifying mirror. It was also found...... that the configuration with four mirrors is well suited as an amplifier device working as an optical transistor since high values of gain up to 40 times could be obtained....

  13. Nonlinear acoustics of water-saturated marine sediments

    DEFF Research Database (Denmark)

    Jensen, Leif Bjørnø

    1976-01-01

    Interest in the acoustic qualities of water-saturated marine sediments has increased considerably during recent years. The use of sources of high-intensity sound in oil propsecting, in geophysical and geological studies of bottom and subbottom materials and profiles and recently in marine...... archaeology has emphasized the need of information about the nonlinear acoustic qualities of water-saturated marine sediments. While the acoustic experiments and theoretical investigations hitherto performed have concentrated on a determination of the linear acoustic qualities of water-saturated marine...... sediments, their parameters of nonlinear acoustics are still unexplored. The strong absorption, increasing about linearly with frequency, found in most marine sediments and the occurrence of velocity dispersion by some marine sediments restrict the number of nonlinear acoustic test methods traditionally...

  14. Soil hydraulic properties near saturation, an improved conductivity model

    DEFF Research Database (Denmark)

    Børgesen, Christen Duus; Jacobsen, Ole Hørbye; Hansen, Søren

    2006-01-01

    of commonly used hydraulic conductivity models and give suggestions for improved models. Water retention and near saturated and saturated hydraulic conductivity were measured for a variety of 81 top and subsoils. The hydraulic conductivity models by van Genuchten [van Genuchten, 1980. A closed-form equation...... for predicting the hydraulic conductivity of unsaturated soils. Soil Sci. Soc. Am. J. 44, 892–898.] (vGM) and Brooks and Corey, modified by Jarvis [Jarvis, 1991. MACRO—A Model of Water Movement and Solute Transport in Macroporous Soils. Swedish University of Agricultural Sciences. Department of Soil Sciences....... Optimising a matching factor (k0) improved the fit considerably whereas optimising the l-parameter in the vGM model improved the fit only slightly. The vGM was improved with an empirical scaling function to account for the rapid increase in conductivity near saturation. Using the improved models...

  15. Mutual boosting of the saturation scales in colliding nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Kopeliovich, B.Z., E-mail: bzk@mpi-hd.mpg.d [Departamento de Fisica, Universidad Tecnica Federico Santa Maria, Instituto de Estudios Avanzados en Ciencias e Ingenieria, Centro Cientifico-Tecnologico de Valparaiso, Casilla 110-V, Valparaiso (Chile); Institut fuer Theoretische Physik der Universitaet, Philosophenweg 19, 69120 Heidelberg (Germany); Pirner, H.J. [Institut fuer Theoretische Physik der Universitaet, Philosophenweg 19, 69120 Heidelberg (Germany); Potashnikova, I.K.; Schmidt, Ivan [Departamento de Fisica, Universidad Tecnica Federico Santa Maria, Instituto de Estudios Avanzados en Ciencias e Ingenieria, Centro Cientifico-Tecnologico de Valparaiso, Casilla 110-V, Valparaiso (Chile)

    2011-03-14

    Saturation of small-x gluons in a nucleus, which has the form of transverse momentum broadening of projectile gluons in pA collisions in the nuclear rest frame, leads to a modification of the parton distribution functions in the beam compared with pp collisions. The DGLAP driven gluon distribution turns out to be suppressed at large x, but significantly enhanced at x<<1. This is a high twist effect. In the case of nucleus-nucleus collisions all participating nucleons on both sides get enriched in gluon density at small x, which leads to a further boosting of the saturation scale. We derive reciprocity equations for the saturation scales corresponding to a collision of two nuclei. The solution of these equations for central collisions of two heavy nuclei demonstrate a significant, up to several times, enhancement of Q{sub sA}{sup 2}, in AA compared with pA collisions.

  16. Central venous oxygen saturation during hypovolaemic shock in humans

    DEFF Research Database (Denmark)

    Madsen, P; Iversen, H; Secher, N H

    1993-01-01

    We compared central venous oxygen saturation and central venous pressure (CVP) as indices of the effective blood volume during 50 degrees head-up tilt (anti-Trendelenburg's position) induced hypovolaemic shock in eight healthy subjects. Head-up tilt increased thoracic electrical impedance from 31...... (28-36) (median and range) to 34 (30-40) Ohm, mean arterial pressure (MAP) from 79 (70-88) to 86 (80-99) mmHg, heart rate (HR) from 67 (56-71) to 99 (78-119) beats min-1 (p ....05) but thereafter remained stable. In contrast, central venous oxygen saturation showed a linear decrease with time from 0.75 (0.69-0.78) at rest to 0.60 (0.49-0.67) (p measurement of central venous oxygen saturation...

  17. Color and emotion: effects of hue, saturation, and brightness.

    Science.gov (United States)

    Wilms, Lisa; Oberfeld, Daniel

    2017-06-13

    Previous studies on emotional effects of color often failed to control all the three perceptual dimensions of color: hue, saturation, and brightness. Here, we presented a three-dimensional space of chromatic colors by independently varying hue (blue, green, red), saturation (low, medium, high), and brightness (dark, medium, bright) in a factorial design. The 27 chromatic colors, plus 3 brightness-matched achromatic colors, were presented via an LED display. Participants (N = 62) viewed each color for 30 s and then rated their current emotional state (valence and arousal). Skin conductance and heart rate were measured continuously. The emotion ratings showed that saturated and bright colors were associated with higher arousal. The hue also had a significant effect on arousal, which increased from blue and green to red. The ratings of valence were the highest for saturated and bright colors, and also depended on the hue. Several interaction effects of the three color dimensions were observed for both arousal and valence. For instance, the valence ratings were higher for blue than for the remaining hues, but only for highly saturated colors. Saturated and bright colors caused significantly stronger skin conductance responses. Achromatic colors resulted in a short-term deceleration in the heart rate, while chromatic colors caused an acceleration. The results confirm that color stimuli have effects on the emotional state of the observer. These effects are not only determined by the hue of a color, as is often assumed, but by all the three color dimensions as well as their interactions.

  18. Saturated Zone Flow and Transport Expert Elicitation Project

    Energy Technology Data Exchange (ETDEWEB)

    Coppersmith, Kevin J.; Perman, Roseanne C.

    1998-01-01

    This report presents results of the Saturated Zone Flow and Transport Expert Elicitation (SZEE) project for Yucca Mountain, Nevada. This project was sponsored by the US Department of Energy (DOE) and managed by Geomatrix Consultants, Inc. (Geomatrix), for TRW Environmental Safety Systems, Inc. The DOE's Yucca Mountain Site Characterization Project (referred to as the YMP) is intended to evaluate the suitability of the site for construction of a mined geologic repository for the permanent disposal of spent nuclear fuel and high-level radioactive waste. The SZEE project is one of several that involve the elicitation of experts to characterize the knowledge and uncertainties regarding key inputs to the Yucca Mountain Total System Performance Assessment (TSPA). The objective of the current project was to characterize the uncertainties associated with certain key issues related to the saturated zone system in the Yucca Mountain area and downgradient region. An understanding of saturated zone processes is critical to evaluating the performance of the potential high-level nuclear waste repository at Yucca Mountain. A major goal of the project was to capture the uncertainties involved in assessing the saturated flow processes, including uncertainty in both the models used to represent the physical processes controlling saturated zone flow and transport, and the parameter values used in the models. So that the analysis included a wide range of perspectives, multiple individual judgments were elicited from members of an expert panel. The panel members, who were experts from within and outside the Yucca Mountain project, represented a range of experience and expertise. A deliberate process was followed in facilitating interactions among the experts, in training them to express their uncertainties, and in eliciting their interpretations. The resulting assessments and probability distributions, therefore, provide a reasonable aggregate representation of the knowledge and

  19. Fabrication and tests of prototype quadrupole magnets for the storage ring of the Advanced Photon Source

    International Nuclear Information System (INIS)

    Kim, S.H.; Thompson, K.M.; Black, E.L.; Jagger, J.M.

    1991-01-01

    Prototype quadrupole magnets for the APS storage ring have been fabricated and tested. Mechanical stability of the magnet poles and acceptable field quality have been achieved. Geometries of the pole-end bevels have been studied in order to simplify the design of the magnet end-plate. The field saturation at different segments of the magnet has been measured to evaluate the magnet efficiency

  20. On the unusual magnetic behaviour of CeRh3B2

    International Nuclear Information System (INIS)

    Galatanu, A; Yamamoto, E; Okubo, T; Yamada, M; Thamizhavel, A; Takeuchi, T; Sugiyama, K; Inada, Y; Onuki, Y

    2003-01-01

    CeRh 3 B 2 is a ferromagnet with an unexpectedly high Curie temperature and low saturation magnetic moments. The origin of its unusual magnetic behaviour remains unelucidated despite various investigations performed in the last two decades. Here we present magnetic results obtained on high-quality single crystals over a wide temperature range. Some new magnetic features are uncovered and possible approaches to explaining its magnetism are briefly discussed

  1. Traveling wave fronts and the transition to saturation

    International Nuclear Information System (INIS)

    Munier, S.; Peschanski, R.

    2004-01-01

    We propose a general method to study the solutions to nonlinear QCD evolution equations, based on a deep analogy with the physics of traveling waves. In particular, we show that the transition to the saturation regime of high energy QCD is identical to the formation of the front of a traveling wave. Within this physical picture, we provide the expressions for the saturation scale and the gluon density profile as a function of the total rapidity and the transverse momentum. The application to the Balitskii-Kovchegov equation for both fixed and running coupling constants confirms the effectiveness of this method

  2. Bistability By Self-Reflection In A Saturable Absorber

    Science.gov (United States)

    Roso-Franco, Luis

    1987-01-01

    Propagation of laser light through a saturable absorber is theoretically studied. Computed steady state solutions of the Maxwell equations describing the unidimensional propagation of a plane monochromatic wave without introducing the slowly-varying envelope approximation are presented showing how saturation effects can influence the absorption of the field. At a certain range of refractive index and extintion coefficients, computed solutions display a very susprising behaviour, and a self-reflected wave appears inside the absorber. This can be useful for a new kind of biestable device, similar to a standard bistable cavity but with the back mirror self-induced by the light.

  3. Effective constants for wave propagation through partially saturated porous media

    International Nuclear Information System (INIS)

    Berryman, J.G.; Thigpen, L.

    1985-01-01

    The multipole scattering coefficients for elastic wave scattering from a spherical inhomogeneity in a fluid-saturated porous medium have been calculated. These coefficients may be used to obtain estimates of the effective macroscopic constants for long-wavelength propagation of elastic waves through partially saturated media. If the volume average of the single scattering from spherical bubbles of gas and liquid is required to vanish, the resulting equations determine the effective bulk modulus, density, and viscosity of the multiphase fluid filling the pores. The formula for the effective viscosity during compressional wave excitation is apparently new

  4. TAE Saturation of Alpha Particle Driven Instability in TFTR

    International Nuclear Information System (INIS)

    Berk, H.L.; Chen, Y.; Gorelenkov, N.N.; White, R.B.

    1998-01-01

    A nonlinear theory of kinetic instabilities near threshold [H.L. Berk, et al., Plasma Phys. Rep. 23, (1997) 842] is applied to calculate the saturation level of Toroidicity-induced Alfvn Eigenmodes (TAE) and be compared with the predictions of (delta)f method calculations [Y. Chen, Ph.D. Thesis, Princeton University, 1998]. Good agreement is observed between the predictions of both methods and the predicted saturation levels are comparable with experimentally measured amplitudes of the TAE oscillations in TFTR [D.J. Grove and D.M. Meade, Nucl. Fusion 25, (1985) 1167

  5. Synthesis and characterization of magnetic diphase ZnFe2O4/γ-Fe2O3 electrospun fibers

    International Nuclear Information System (INIS)

    Arias, M.; Pantojas, V.M.; Perales, O.; Otano, W.

    2011-01-01

    Magnetic nanofibers of ZnFe 2 O 4 /γ-Fe 2 O 3 composite were synthesized by electrospinning from a sol-gel solution containing a molar ratio (Fe/Zn) of 3. The effects of the calcination temperature on phase composition, particle size and magnetic properties have been investigated. Zinc ferrite fibers were obtained by calcinating the electrospun fibers in air from 300 to 800 deg. C and characterized by thermogravimetric analyses, Fourier transformed infrared spectroscopy, X-ray photoemission spectroscopy, X-ray diffraction, vibration sample magnetometry and magnetic force microscopy. The resulting fibers, with diameters ranging from 90 to 150 nm, were ferrimagnetic with high saturation magnetization as compared to bulk. An increase in the calcination temperature resulted in an increase in particle size and saturation magnetization. The observed increase in saturation magnetization was most likely due to the formation and growth of ZnFe 2 O 4 /γ-Fe 2 O 3 diphase crystals. The highest saturation magnetization (45 emu/g) was obtained for fibers calcined at 800 deg. C. - Research highlights: → Nanofibers were produced by electrospinning from a sol-gel. → ZnFe 2 O 4 /γ-Fe 2 O 3 formed after cacination in air from 300 to 800 deg. C. → Fibers were ferrimagnetic with high saturation magnetization. → Crystallite particle size and saturation magnetization increase with temperature. → Magnetic domains with sizes similar to topographical grains were observed.

  6. Temperature dependence of microwave oscillations in magnetic tunnel junctions with a perpendicularly magnetized free layer

    International Nuclear Information System (INIS)

    Guo, Peng; Feng, Jiafeng; Wei, Hongxiang; Han, Xiufeng; Fang, Bin; Zhang, Baoshun; Zeng, Zhongming

    2015-01-01

    We experimentally study the temperature dependence of the spin-transfer-torque-induced microwave oscillations in MgO-based magnetic tunnel junction nanopillars with a perpendicularly magnetized free layer. We demonstrate that the oscillation frequency increases rapidly with decreasing temperature, which is mainly ascribed to the temperature dependence of both the saturation magnetization and the perpendicular magnetic anisotropy. We also find that a strong temperature dependence of the output power while a nonmonotonic temperature dependence of spectral linewidth are maintained for a constant dc bias in measured temperature range. Possible mechanisms leading to the different dependences of oscillation frequency, output power, and linewidth are discussed

  7. Magnetic Spinner

    Science.gov (United States)

    Ouseph, P. J.

    2006-01-01

    A science toy sometimes called the "magnetic spinner" is an interesting class demonstration to illustrate the principles of magnetic levitation. It can also be used to demonstrate Faraday's law and a horizontally suspended physical pendulum. The levitated part contains two circular magnets encased in a plastic housing. Each magnet stays…

  8. Magnetic anisotropies and magnetic switching in Co films

    Science.gov (United States)

    Bland, J. A. C.; Baird, M. J.; Leung, H. T.; Ives, A. J. R.; Mackay, K. D.; Hughes, H. P.

    1992-07-01

    We have used the magneto-optical Kerr effect to investigate the role of the substrate and growth conditions in determining the magnetic switching behaviour of Co films in the thickness range 100-200 Å supported by GaAs(001) and Si(111) substrates. We discuss the anisotropic magnetic hysteresis behaviour observed for Co/GaAs and Co/Si films in terms of coherent rotation of the magnetisation vector during magnetic switching. Equivalent films supported by glass substrates are found to be almost isotropic in-plane. The in-plane coercive and saturation fields are observed to lie in the range 20-80 Oe but perpendicular saturation fields of 25 and 19 kOe are found for the Co/Si and Co/GaAs systems respectively which substantially exceed the demagnetising field in each case. The measured perpendicular anisotropy fields differ strongly from the values for hcp and bcc Co and are attributed to the details of the interface and film structure. We also report strongly frequency dependent magnetic switching behaviour in these Co films.

  9. Enhanced signal dispersion in saturation transfer difference experiments by conversion to a 1D-STD-homodecoupled spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Martin-Pastor, Manuel; Vega-Vazquez, Marino [Universidade de Santiago de Compostela, Laboratorio Integral de Dinamica e Estructura de Biomoleculas Jose R. Carracido, Unidade de Resonancia Magnetica, Edificio CACTUS, RIAIDT (Spain); Capua, Antonia De [Seconda Universita degli Studi di Napoli, Dipartimento di Scienze Ambientali (Italy); Canales, Angeles [Centro de Investigaciones Biologicas, CSIC, Departamento de Estructura y funcion de proteinas (Spain); Andre, Sabine; Gabius, Hans-Joachim [Ludwig-Maximilians-Universitaet, Institut fuer Physiologische Chemie, Tieraerztliche Fakultaet (Germany); Jimenez-Barbero, Jesus [Centro de Investigaciones Biologicas, CSIC, Departamento de Estructura y funcion de proteinas (Spain)], E-mail: JJbarbero@cib.csic.es

    2006-10-15

    The saturation transfer difference (STD) experiment is a rich source of information on topological aspects of ligand binding to a receptor. The epitope mapping is based on a magnetization transfer after signal saturation from the receptor to the ligand, where interproton distances permit this process. Signal overlap in the STD spectrum can cause difficulties to correctly assign and/or quantitate the measured enhancements. To address this issue we report here a modified version of the routine experiment and a processing scheme that provides a 1D-STD homodecoupled spectrum (i.e. an experiment in which all STD signals appear as singlets) with line widths similar to those in original STD spectrum. These refinements contribute to alleviate problems of signal overlap. The experiment is based on 2D-J-resolved spectroscopy, one of the fastest 2D experiments under conventional data sampling in the indirect dimension, and provides excellent sensitivity, a key factor for the difference experiments.

  10. 31P saturation transfer and phosphocreatine imaging in the monkey brain

    International Nuclear Information System (INIS)

    Mora, B.; Narasimhan, P.T.; Ross, B.D.; Allman, J.; Barker, P.B.

    1991-01-01

    31 P magnetic resonance imaging with chemical-shift discrimination by selective excitation has been employed to determine the phosphocreatine (PCr) distribution in the brains of three juvenile macaque monkeys. PCr images were also obtained while saturating the resonance of the γ-phosphate of ATP, which allowed the investigation of the chemical exchange between PCr and the γ-phosphate of ATP catalyzed by creatine kinase. Superposition of the PCr images over the proton image of the same monkey brain revealed topological variations in the distribution of PCr and creatine kinase activity. PCr images were also obtained with and without visual stimulation. In two out of four experiments, an apparently localized decrease in PCr concentration was noted in visual cortex upon visual stimulation. This result is interpreted in terms of a possible role for the local ADP concentration in stimulating the accompanying metabolic response

  11. Generation and saturation of large-scale flows in flute turbulence

    International Nuclear Information System (INIS)

    Sandberg, I.; Isliker, H.; Pavlenko, V. P.; Hizanidis, K.; Vlahos, L.

    2005-01-01

    The excitation and suppression of large-scale anisotropic modes during the temporal evolution of a magnetic-curvature-driven electrostatic flute instability are numerically investigated. The formation of streamerlike structures is attributed to the linear development of the instability while the subsequent excitation of the zonal modes is the result of the nonlinear coupling between linearly grown flute modes. When the amplitudes of the zonal modes become of the same order as that of the streamer modes, the flute instabilities get suppressed and poloidal (zonal) flows dominate. In the saturated state that follows, the dominant large-scale modes of the potential and the density are self-organized in different ways, depending on the value of the ion temperature

  12. Quantitative Analysis of L-Edge White Line Intensities: The Influence of Saturation and Transverse Coherence

    International Nuclear Information System (INIS)

    Hahlin, A.

    2001-01-01

    We have performed x-ray absorption spectroscopy at the Fe, Ni, and Co L2,3 edges of in situ grown thin magnetic films. We compare electron yield measurements performed at SSRL and BESSY-I. Differences in the L2,3 white line intensities are found for all three elements, comparing data from the two facilities. We propose a correlation between spectral intensities and the degree of spatial coherence of the exciting radiation. The electron yield saturation effects are stronger for light with a higher degree of spatial coherence. Therefore the observed, coherence related, intensity variations are due to an increase in the absorption coefficient, and not to secondary channel related effects

  13. Quantitative analysis of L-edge white line intensities: the influence of saturation and transverse coherence.

    Science.gov (United States)

    Hahlin, A; Karis, O; Brena, B; Dunn, J H; Arvantis, D

    2001-03-01

    We have performed x-ray absorption spectroscopy at the Fe, Ni, and Co L2,3 edges of in situ grown thin magnetic films. We compare electron yield measurements performed at SSRL and BESSY-I. Differences in the L2,3 white line intensities are found for all three elements, comparing data from the two facilities. We propose a correlation between spectral intensities and the degree of spatial coherence of the exciting radiation. The electron yield saturation effects are stronger for light with a higher degree of spatial coherence. Therefore the observed, coherence related, intensity variations are due to an increase in the absorption coefficient, and not to secondary channel related effects.

  14. Observation of room temperature saturated ferroelectric polarization in Dy substituted BiFeO3 ceramics

    KAUST Repository

    Zhang, Shuxia

    2012-04-06

    High quality Bi1− x Dy x FeO3 (0 ≤ x ≤ 0.15) ceramics have been fabricated by sintering Dy-doped BiFeO3 (BFO) precursor powders at a low temperature of 780 °C. The magnetic properties of BFO were improved by the introduction of Dy on the Bi-site. More importantly, well saturated ferroelectric hysteresis loops and polarization switching currents have been observed at room temperature. A large remnant polarization (2P r) value of 62 μC/cm2 is achieved, which is the highest value reported so far for rare-earth-doped BFO ceramics. Moreover, mechanisms for improved multiferroic properties depending on chemical doping-caused structure evolutions have also been discussed.

  15. Observation of room temperature saturated ferroelectric polarization in Dy substituted BiFeO3 ceramics

    KAUST Repository

    Zhang, Shuxia; Wang, Lei; Chen, Yao; Wang, Dongliang; Yao, Yingbang; Ma, Yanwei

    2012-01-01

    High quality Bi1− x Dy x FeO3 (0 ≤ x ≤ 0.15) ceramics have been fabricated by sintering Dy-doped BiFeO3 (BFO) precursor powders at a low temperature of 780 °C. The magnetic properties of BFO were improved by the introduction of Dy on the Bi-site. More importantly, well saturated ferroelectric hysteresis loops and polarization switching currents have been observed at room temperature. A large remnant polarization (2P r) value of 62 μC/cm2 is achieved, which is the highest value reported so far for rare-earth-doped BFO ceramics. Moreover, mechanisms for improved multiferroic properties depending on chemical doping-caused structure evolutions have also been discussed.

  16. Magnetic skyrmions

    Science.gov (United States)

    2018-06-01

    Welcome to the special issue of Journal of Magnetism and Magnetic Materials on magnetic skyrmions. We are proud to present, with great pleasure, a timely collection of 9 original research articles on the recent hot topic "magnetic skyrmions" which studies the static and dynamic properties of skyrmions and the methods to control them in a variety of ways, including magnetic field, electric current and applied strain.

  17. Transfer Rate Edited experiment for the selective detection of Chemical Exchange via Saturation Transfer (TRE-CEST)

    Science.gov (United States)

    Friedman, Joshua I.; Xia, Ding; Regatte, Ravinder R.; Jerschow, Alexej

    2015-07-01

    Chemical Exchange Saturation Transfer (CEST) magnetic resonance experiments have become valuable tools in magnetic resonance for the detection of low concentration solutes with far greater sensitivity than direct detection methods. Accurate measures of rates of chemical exchange provided by CEST are of particular interest to biomedical imaging communities where variations in chemical exchange can be related to subtle variations in biomarker concentration, temperature and pH within tissues using MRI. Despite their name, however, traditional CEST methods are not truly selective for chemical exchange and instead detect all forms of magnetization transfer including through-space NOE. This ambiguity crowds CEST spectra and greatly complicates subsequent data analysis. We have developed a Transfer Rate Edited CEST experiment (TRE-CEST) that uses two different types of solute labeling in order to selectively amplify signals of rapidly exchanging proton species while simultaneously suppressing 'slower' NOE-dominated magnetization transfer processes. This approach is demonstrated in the context of both NMR and MRI, where it is used to detect the labile amide protons of proteins undergoing chemical exchange (at rates ⩾ 30 s-1) while simultaneously eliminating signals originating from slower (∼5 s-1) NOE-mediated magnetization transfer processes. TRE-CEST greatly expands the utility of CEST experiments in complex systems, and in-vivo, in particular, where it is expected to improve the quantification of chemical exchange and magnetization transfer rates while enabling new forms of imaging contrast.

  18. Transfer Rate Edited experiment for the selective detection of Chemical Exchange via Saturation Transfer (TRE-CEST).

    Science.gov (United States)

    Friedman, Joshua I; Xia, Ding; Regatte, Ravinder R; Jerschow, Alexej

    2015-07-01

    Chemical Exchange Saturation Transfer (CEST) magnetic resonance experiments have become valuable tools in magnetic resonance for the detection of low concentration solutes with far greater sensitivity than direct detection methods. Accurate measures of rates of chemical exchange provided by CEST are of particular interest to biomedical imaging communities where variations in chemical exchange can be related to subtle variations in biomarker concentration, temperature and pH within tissues using MRI. Despite their name, however, traditional CEST methods are not truly selective for chemical exchange and instead detect all forms of magnetization transfer including through-space NOE. This ambiguity crowds CEST spectra and greatly complicates subsequent data analysis. We have developed a Transfer Rate Edited CEST experiment (TRE-CEST) that uses two different types of solute labeling in order to selectively amplify signals of rapidly exchanging proton species while simultaneously suppressing 'slower' NOE-dominated magnetization transfer processes. This approach is demonstrated in the context of both NMR and MRI, where it is used to detect the labile amide protons of proteins undergoing chemical exchange (at rates⩾30s(-1)) while simultaneously eliminating signals originating from slower (∼5s(-1)) NOE-mediated magnetization transfer processes. TRE-CEST greatly expands the utility of CEST experiments in complex systems, and in-vivo, in particular, where it is expected to improve the quantification of chemical exchange and magnetization transfer rates while enabling new forms of imaging contrast. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Preparation and characterization of magnetic chitosan particles for hyperthermia application

    International Nuclear Information System (INIS)

    Park, Ji-Ho; Im, Ki-Hyeong; Lee, Se-Ho; Kim, Dong-Hyun; Lee, Doug-Youn; Lee, Yong-Keun; Kim, Kwang-Mahn; Kim, Kyoung-Nam

    2005-01-01

    The size and shape of magnetic chitosan particles were found to be dependent on both the barium ferrite/chitosan (BF/C) ratio and viscosity of a chitosan solution. The saturation magnetization of magnetic chitosan particles varied directly with the BF/C ratio, while coercivity remained almost constant. Notably, incorporated chitosan was shown to exert substantial activity with regard to low cytotoxicity and high heating rate

  20. Saturation behaviour of the LHC NEG coated beam pipes

    CERN Document Server

    Porcelli, T; Lanza, G; Baglin, V; Jimenez, J M

    2012-01-01

    In the CERN Large Hadron Collider (LHC), about 6 km of the UHV beam pipe are at room temperature and serve as experimental or utility insertions. TiZrV non-evaporable getter (NEG) coating is used to maintain the design pressure during beam operation. Molecular desorption due to dynamic effects is stimulated during protons operation at high intensity. This phenomenon produces an important gas load from the vacuum chamber walls, which could lead to a partial or total saturation of the NEG coating. To keep the design vacuum performances and to schedule technical interventions for NEG reactivation, it is necessary to take into account all these aspects and to regularly evaluate the saturation level of the NEG coating. Experimental studies of a typical LHC vacuum sector were conducted in the laboratory in order to identify the best method to assess the saturation level of the beam pipe. Partial saturation of the NEG was performed and the effective pumping speed, transmission and capture probability are analysed.

  1. Experimental Validation of the Invariance of Electrowetting Contact Angle Saturation

    NARCIS (Netherlands)

    Chevalliot, S.; Dhindsa, M.; Kuiper, S.; Heikenfeld, J.

    2011-01-01

    Basic electrowetting theory predicts that a continued increase in applied voltage will allow contact angle modulation to zero degrees. In practice, the effect of contact angle saturation has always been observed to limit the contact angle modulation, often only down to a contact angle of 60 to 70°.

  2. Monte Carlo simulation of AB-copolymers with saturating bonds

    DEFF Research Database (Denmark)

    Chertovich, A.C.; Ivanov, V.A.; Khokhlov, A.R.

    2003-01-01

    Structural transitions in a single AB-copolymer chain where saturating bonds can be formed between A- and B-units are studied by means of Monte Carlo computer simulations using the bond fluctuation model. Three transitions are found, coil-globule, coil-hairpin and globule-hairpin, depending...

  3. The Saturation of Several Universal Inequalities in Information-Processing

    International Nuclear Information System (INIS)

    Zhang Lin; Wu Jun-De; Fei Shao-Ming

    2015-01-01

    In this paper, we characterize the saturation of four universal inequalities in quantum information theory, including a variant version of strong subadditivity inequality for von Neumann entropy, the coherent information inequality, the Holevo quantity, and average entropy inequalities. These results shed new light on quantum information inequalities. (paper)

  4. Effect of soil saturation on denitrification in a grassland soil

    Directory of Open Access Journals (Sweden)

    L. M. Cardenas

    2017-10-01

    Full Text Available Nitrous oxide (N2O is of major importance as a greenhouse gas and precursor of ozone (O3 destruction in the stratosphere mostly produced in soils. The soil-emitted N2O is generally predominantly derived from denitrification and, to a smaller extent, nitrification, both processes controlled by environmental factors and their interactions, and are influenced by agricultural management. Soil water content expressed as water-filled pore space (WFPS is a major controlling factor of emissions and its interaction with compaction, has not been studied at the micropore scale. A laboratory incubation was carried out at different saturation levels for a grassland soil and emissions of N2O and N2 were measured as well as the isotopocules of N2O. We found that flux variability was larger in the less saturated soils probably due to nutrient distribution heterogeneity created from soil cracks and consequently nutrient hot spots. The results agreed with denitrification as the main source of fluxes at the highest saturations, but nitrification could have occurred at the lower saturation, even though moisture was still high (71 % WFSP. The isotopocules data indicated isotopic similarities in the wettest treatments vs. the two drier ones. The results agreed with previous findings where it is clear there are two N pools with different dynamics: added N producing intense denitrification vs. soil N resulting in less isotopic fractionation.

  5. Saturating time-delay transformer for overcurrent protection

    Science.gov (United States)

    Praeg, Walter F.

    1977-01-01

    Electrical loads connected to d-c supplies are protected from damage by overcurrent in the case of a load fault by connecting in series with the load a saturating transformer that detects a load fault and limits the fault current to a safe level for a period long enough to correct the fault or else disconnect the power supply.

  6. Facilitated transport of copper with hydroxyapatite nanoparticles in saturated sand

    Science.gov (United States)

    Saturated packed column experiments were conducted to investigate the facilitated transport of Cu with hydroxyapatite nanoparticles (nHAP) at different pore water velocities (0.22-2.2 cm min–1), solution pH (6.2-9.0), and fraction of Fe oxide coating on grain surfaces (', 0-0.36). The facilitated tr...

  7. Stochastic analysis of radionuclide migration in saturated-unsaturated soils

    International Nuclear Information System (INIS)

    Kawanishi, Moto

    1988-01-01

    In Japan, LLRW (low level radioactive wastes) generated from nuclear power plants shall be started to store concentrically in the Shimokita site from 1990, and those could be transformed into land disposal if the positive safety is confirmed. Therefore, it is hoped that the safety assessment method shall be successed for the land disposal of LLRW. In this study, a stochastic model to analyze the radionuclide migration in saturated-unsaturated soils was constructed. The principal results are summarized as follows. 1) We presented a generalized idea for the modeling of the radionuclide migration in saturated-unsaturated soils as an advective-dispersion phenomena followed by the decay of radionuclides and those adsorption/desorption in soils. 2) Based on the radionuclide migration model mentioned above, we developed a stochastic analysis model on radionuclide migration in saturated-unsaturated soils. 3) From the comparison between the simulated results and the exact solution on a few simple one-dimensional advective-dispersion problems of radionuclides, the good validity of this model was confirmed. 4) From the comparison between the simulated results by this model and the experimental results of radionuclide migration in a one-dimensional unsaturated soil column with rainfall, the good applicability was shown. 5) As the stochastic model such as this has several advantages that it is easily able to represent the image of physical phenomena and has basically no numerical dissipation, this model should be more applicable to the analysis of the complicated radionuclide migration in saturated-unsaturated soils. (author)

  8. Dynamical study of a laser with a saturable absorber

    Energy Technology Data Exchange (ETDEWEB)

    Dignowity, D; RamIrez, R [Centro de Investigaciones en Optica, Loma del Bosque 115, Col. Lomas del Campestre, 37150, Leon, Guanajuato (Mexico)

    2005-01-01

    The study of a laser including a saturable absorber is presented. The non-linear system describing the complex dynamics of the laser is presented. The laser is shown to operate in several regimes depending on the parameters used. It is also shown how the control of the laser is possible depending on the operating regime parameters.

  9. Centrifuge modeling of LNAPL transport in partially saturated sand

    NARCIS (Netherlands)

    Esposito, G.; Allersma, H.G.B.; Selvadurai, A.P.S.

    1999-01-01

    Model tests were performed at the Geotechnical Centrifuge Facility of Delft University of Technology, The Netherlands, to examine the mechanics of light nonaqueous phase liquid (LNAPL) movement in a partially saturated porous granular medium. The experiment simulated a 2D spill of LNAPL in an

  10. Enhancement of aromatic and saturated hydrocarbon by modified ...

    African Journals Online (AJOL)

    Three sediment samples collected from the Qua Iboe River System and eighteen different column packing ratios of silica gel and alumina were used in this investigation. The variation of the composition of the stationary phase (silica gel and alumina, SA) gave different yields of aromatic and saturated hydrocarbons. In all the ...

  11. Asymmetric gain-saturated spectrum in fiber optical parametric amplifiers

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh; Rottwitt, Karsten; Galili, Michael

    2012-01-01

    We demonstrate experimentally and numerically an unexpected spectral asymmetry in the saturated-gain spectrum of single-pump fiber optical parametric amplifiers. The interaction between higher-order four-wave mixing products and dispersive waves radiated as an effect of third-order dispersion inf...... characteristics of the amplifier and shows local maxima for specific dispersion values....

  12. Influence of soil particle shape on saturated hydraulic conductivity

    Directory of Open Access Journals (Sweden)

    Zięba Zofia

    2017-03-01

    Full Text Available The aim of this paper is to define the correlation between the geometry of grains and saturated hydraulic conductivity of soils. The particle shape characteristics were described by the ζ0C index (Parylak, 2000, which expresses the variability of several shape properties, such as sphericity, angularity and roughness.

  13. Surface wave propagation in a fluid-saturated incompressible ...

    Indian Academy of Sciences (India)

    dilatational and one rotational elastic waves in fluid-saturated porous solids. Biot theory ..... If the pore liquid is absent or gas is filled in the pores, then ρF ..... Biot M A (1962) Mechanics of deformation and acoustic propagation in porous media.

  14. Reliable monitoring of oxygen saturation via pulse oximetry: Which ...

    African Journals Online (AJOL)

    This study focuses on identifying the best site for placement of pulse oximeter probe accurate measuring of oxygen saturation. Twenty-three healthy male volunteers aged 20 to 40 years old were recruited in this study. Cold pressor test was done to stim 460 measurements of SpO2level were obtained throughout the study.

  15. Effect Of Intraruminal Infussion Of Saturated And Unsaturated Fatty ...

    African Journals Online (AJOL)

    This study describes the effect of intraruminal infusion of diferent proportions of palmitic (saturated fatty acid) and linolenic (unsaturated fatty acid) on rumen degradability of organic matter fraction of Pennisetium purpureum, total volatile fatty acid and total methane productions in West African Dwarf sheep. Five combination ...

  16. Simple adaptive control for quadcopters with saturated actuators

    Science.gov (United States)

    Borisov, Oleg I.; Bobtsov, Alexey A.; Pyrkin, Anton A.; Gromov, Vladislav S.

    2017-01-01

    The stabilization problem for quadcopters with saturated actuators is considered. A simple adaptive output control approach is proposed. The control law "consecutive compensator" is augmented with the auxiliary integral loop and anti-windup scheme. Efficiency of the obtained regulator was confirmed by simulation of the quadcopter control problem.

  17. Relating saturation capacity to charge density in strong cation exchangers.

    Science.gov (United States)

    Steinebach, Fabian; Coquebert de Neuville, Bertrand; Morbidelli, Massimo

    2017-07-21

    In this work the relation between physical and chemical resin characteristics and the total amount of adsorbed protein (saturation capacity) for ion-exchange resins is discussed. Eleven different packing materials with a sulfo-functionalization and one multimodal resin were analyzed in terms of their porosity, pore size distribution, ligand density and binding capacity. By specifying the ligand density and binding capacity by the total and accessible surface area, two different groups of resins were identified: Below a ligand density of approx. 2.5μmol/m 2 area the ligand density controls the saturation capacity, while above this limit the accessible surface area becomes the limiting factor. This results in a maximum protein uptake of around 2.5mg/m 2 of accessible surface area. The obtained results allow estimating the saturation capacity from independent resin characteristics like the saturation capacity mainly depends on "library data" such as the accessible and total surface area and the charge density. Hence these results give an insight into the fundamentals of protein adsorption and help to find suitable resins, thus limiting the experimental effort in early process development stages. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Transformation of saturated nitrogen-containing heterocyclic compounds by microorganisms.

    Science.gov (United States)

    Parshikov, Igor A; Silva, Eliane O; Furtado, Niege A J C

    2014-02-01

    The saturated nitrogen-containing heterocyclic compounds include many drugs and compounds that may be used as synthons for the synthesis of other pharmacologically active substances. The need for new derivatives of saturated nitrogen-containing heterocycles for organic synthesis, biotechnology and the pharmaceutical industry, including optically active derivatives, has increased interest in microbial synthesis. This review provides an overview of microbial technologies that can be valuable to produce new derivatives of saturated nitrogen-containing heterocycles, including hydroxylated derivatives. The chemo-, regio- and enantioselectivity of microbial processes can be indispensable for the synthesis of new compounds. Microbial processes carried out with fungi, including Beauveria bassiana, Cunninghamella verticillata, Penicillium simplicissimum, Aspergillus niger and Saccharomyces cerevisiae, and bacteria, including Pseudomonas sp., Sphingomonas sp. and Rhodococcus erythropolis, biotransform many substrates efficiently. Among the biological activities of saturated nitrogen-containing heterocyclic compounds are antimicrobial, antitumor, antihypertensive and anti-HIV activities; some derivatives are effective for the treatment and prevention of malaria and trypanosomiasis, and others are potent glycosidase inhibitors.

  19. PARTON SATURATION, PRODUCTION, AND EQUILIBRATION IN HIGH ENERGY NUCLEAR COLLISIONS

    International Nuclear Information System (INIS)

    VENUGOPALAN, R.

    1999-01-01

    Deeply inelastic scattering of electrons off nuclei can determine whether parton distributions saturate at HERA energies. If so, this phenomenon will also tell us a great deal about how particles are produced, and whether they equilibrate, in high energy nuclear collisions

  20. Hydrocarbon saturation determination using acoustic velocities obtained through casing

    Science.gov (United States)

    Moos, Daniel

    2010-03-09

    Compressional and shear velocities of earth formations are measured through casing. The determined compressional and shear velocities are used in a two component mixing model to provides improved quantitative values for the solid, the dry frame, and the pore compressibility. These are used in determination of hydrocarbon saturation.

  1. Nuclear determination of saturation profiles in core plugs

    International Nuclear Information System (INIS)

    Sletsgaard, J.; Oelgaard, P.L.

    1997-01-01

    A method to determine liquid saturations in core plugs during flooding is of importance when the relative permeability and capillary pressure function are to be determined. This part of the EFP-95 project uses transmission of γ-radiation to determine these saturations. In γ-transmission measurements, the electron density of the given substance is measured. This is an advantage as compared to methods that use electric conductivity, since neither oil nor gas conducts electricity. At the moment a single 137 Cs-source is used, but a theoretical investigation of whether it is possible to determine three saturations, using two radioactive sources with different γ-energies, has been performed. Measurements were made on three core plugs. To make sure that the measurements could be reproduced, all the plugs had a point of reference, i.e. a mark so that it was possible to place the plug same way every time. Two computer programs for calculation of saturation and porosity and the experimental setup are listed. (EG)

  2. Effect of weightlessness on mineral saturation of bone tissue

    Science.gov (United States)

    Krasnykh, I. G.

    1975-01-01

    X-ray photometry of bone density established dynamic changes in mineral saturation of bone tissues for Soyuz spacecraft and Salyut orbital station crews. Calcaneus optical bone densities in all crew members fell below initial values; an increase in spacecrew exposure time to weightlessness conditions also increased the degree of decalcification. Demineralization under weightlessness conditions took place at a higher rate than under hypodynamia.

  3. Double shock dynamics induced by the saturation of defocusing nonlinearities

    KAUST Repository

    Crosta, Matteo

    2012-01-01

    We show that the saturation of defocusing nonlinearities leads to qualitative changes in the onset of wave breaking, determining double shock formation whose regularization occurs in terms of antidark solitons. In a given material, the crossover between different regimes can be controlled by changing the input intensity. © 2012 Optical Society of America.

  4. Shear weakening for different lithologies observed at different saturation stages

    Science.gov (United States)

    Diethart-Jauk, Elisabeth; Gegenhuber, Nina

    2018-01-01

    For this study, samples from different lithologies ("Leitha"-limestone, "Dachstein"-limestone, "Haupt"-dolomite, "Bunt"-sandstone, Grey Berea sandstone, granite, quartzite and basalt) were selected. Samples were dried at 70 °C, respectively 105 °C and were saturated with brine. Mass, porosity, permeability, compressional and shear wave velocity were determined from dry and brine saturated samples at laboratory conditions, based on an individual measurement program. Shear modulus was calculated to find out, if shear weakening exists for the dataset. Shear weakening means that shear modulus of dry samples is higher than of saturated samples, but it is assumed that shear modulus is unaffected by saturation. "Dachstein"-limestone and basalt show shear weakening, quartzite samples show both weakening and hardening. Granite samples are affected by temperature, after drying with 105 °C no change can be observed anymore. "Bunt"-sandstone samples show a change in the shear modulus in a small extent, although they may contain clay minerals. The other lithologies show no effect. Explanations for carbonate samples can be the complicated pore structure, for basalt it could be that weathering creates clay minerals which are known as causes for a change of the shear modulus. Fluid viscosity can also be an important factor.

  5. Significance of saturation index of certain clay minerals in shallow ...

    Indian Academy of Sciences (India)

    Significance of saturation index of certain clay minerals in shallow ... The value of ionic activity product (IAP) for a mineral ... where γi is the activity coefficient of ionic species ...... Domenico P A and Schwartz W 1990 Physical and Chemical.

  6. Investigation of paramagnetic saturation in lanthanum manganese nitrate

    NARCIS (Netherlands)

    Flokstra, Jakob; Meijer, H.C.; Bots, G.J.C.; Verheij, W.A.; van der Marel, L.C.

    1973-01-01

    Paramagnetic saturation of lanthanum manganese nitrate, La2Mn3(NO3)12·24H2O, has been investigated at liquid He temperatures in a static as well as a dynamical way. With the aid of the molecular-field theory the Casimir and Du Pré dispersion and absorption curves are adapted explicitly to the

  7. Upscaling soil saturated hydraulic conductivity from pore throat characteristics

    Science.gov (United States)

    Upscaling and/or estimating saturated hydraulic conductivity Ksat at the core scale from microscopic/macroscopic soil characteristics has been actively under investigation in the hydrology and soil physics communities for several decades. Numerous models have beendeveloped based on different approac...

  8. Mulching an Arenic Hapludult at Umudike: Effects on saturated ...

    African Journals Online (AJOL)

    A study was carried out over two cropping seasons on an Arenic Hapludult at Umudike, southeastern Nigeria, to investigate and determine the quantity and type of mulch material that would optimize the rhizome yield of turmeric (Curcuma longa Linn) and improve the saturated hydraulic conductivity of the soil. The turmeric ...

  9. Saturation of single toroidal number Alfvén modes

    International Nuclear Information System (INIS)

    Wang, X; Briguglio, S

    2016-01-01

    The results of numerical simulations are presented to illustrate the saturation mechanism of a single toroidal number Alfvén mode, driven unstable, in a tokamak plasma, by the resonant interaction with energetic ions. The effects of equilibrium geometry non-uniformities and finite mode radial width on the wave-particle nonlinear dynamics are discussed. Saturation occurs as the fast-ion density flattening produced by the radial flux associated to the resonant particles captured in the potential well of the Alfvén wave extends over the whole region where mode-particle power exchange can take place. The occurrence of two different saturation regimes is shown. In the first regime, dubbed resonance detuning, that region is limited by the resonance radial width (that is, the width of the region where the fast-ion resonance frequency matches the mode frequency). In the second regime, called radial decoupling, the power exchange region is limited by the mode radial width. In the former regime, the mode saturation amplitude scales quadratically with the growth rate; in the latter, it scales linearly. The occurrence of one or the other regime can be predicted on the basis of linear dynamics: in particular, the radial profile of the fast-ion resonance frequency and the mode structure. Here, we discuss how such properties can depend on the considered toroidal number and compare simulation results with the predictions obtained from a simplified nonlinear pendulum model. (paper)

  10. 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.

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

    International Nuclear Information System (INIS)

    Lv, Yiliang; Wang, Guobin; Li, Liang

    2015-01-01

    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 (Sm 2 Co 17 ) 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Yiliang; Wang, Guobin [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan (China); Li, Liang [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan (China); State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan (China)

    2015-03-15

    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 (Sm{sub 2}Co{sub 17}) 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.

  13. Simulation of consolidation in partially saturated soil materials

    International Nuclear Information System (INIS)

    Narasimhan, T.N.

    1982-03-01

    Partially saturated soil materials undergo consolidation, heave, collapse and failure due to changes in pore fluid pressure. The precise nature of the mechanics of such deformations is only poorly understood at present. Experimental evidence has shown that the volume change behavior of unsaturated soils cannot be adequately explained through changes in effective stress, even when a saturation dependent parameter is incorporated into the definition of effective stress. Two independent stress-state variables, involving combinations of total stress, pore air pressure and pore water pressure, are required to characterize volume changes and saturation changes in the partially saturated state. In general, two coupled conservation equations, one for the water-phase and the other for the air-phase need to be solved in order to predict the deformation behavior of unsaturated soils. If directional displacements and changes in the stress-field are required, then the conservation equations are to be integrated with an additional set of multi-dimensional force balance equations. For lack of a sufficient understanding of elastic constants such as Poisson's Ratio and Lame's constants as applied to unsaturated soils, little has been achieved so far in integrating the conservation equations and the force balance equations. For the long-term modeling of consolidation with respect to uranium mill tailings, it may be acceptable and economical to solve a single conservation equation for water, assuming that the air-phase is continuous and is at atmospheric pressure everywhere in the soil. The greatest challenge to modeling consolidation in the unsaturated zone at the presnt time is to develop enough experimental data defining the variation of void ratio and saturation with reference to the two chosen stress-state variables

  14. Modelling suction instabilities in soils at varying degrees of saturation

    Directory of Open Access Journals (Sweden)

    Buscarnera Giuseppe

    2016-01-01

    Full Text Available Wetting paths imparted by the natural environment and/or human activities affect the state of soils in the near-surface, promoting transitions across different regimes of saturation. This paper discusses a set of techniques aimed at quantifying the role of hydrologic processes on the hydro-mechanical stability of soil specimens subjected to saturation events. Emphasis is given to the mechanical conditions leading to coupled flow/deformation instabilities. For this purpose, energy balance arguments for three-phase systems are used to derive second-order work expressions applicable to various regimes of saturation. Controllability analyses are then performed to relate such work input with constitutive singularities that reflect the loss of strength under coupled and/or uncoupled hydro-mechanical forcing. A suction-dependent plastic model is finally used to track the evolution of stability conditions in samples subjected to wetting, thus quantifying the growth of the potential for coupled failure modes upon increasing degree of saturation. These findings are eventually linked with the properties of the field equations that govern pore pressure transients, thus disclosing a conceptual link between the onset of coupled hydro-mechanical failures and the evolution of suction with time. Such results point out that mathematical instabilities caused by a non-linear suction dependent behaviour play an important role in the advanced constitutive and/or numerical tools that are commonly used for the analysis of geomechanical problems in the unsaturated zone, and further stress that the relation between suction transients and soil deformations is a key factor for the interpretation of runaway failures caused by intense saturation events.

  15. On the influence of mechanical and magnetic characteristics on the field quality of superconducting magnets

    International Nuclear Information System (INIS)

    Abramov, A.G.; Ershov, S.Yu.; Daikovsky, A.G.; Ryabov, A.D.; Tkachenko, N.P.

    1992-01-01

    The paper presents a numerical analysis of the effect of mechanical processes in a superconducting magnet, beginning with the coil assembly fabrication and ending with energizing it. The purpose of our work was to find the correlations between the harmonics and mechanical behaviour of the design and hence, to detect possible defects in the production technology and show the possible ways of solving the problems. The effects related to the saturation of the magnetic shield are analysed as well. (Author)

  16. Pressure effects on single chain magnets

    Energy Technology Data Exchange (ETDEWEB)

    Mito, M. E-mail: mitoh@elcs.kyutech.ac.jp; Shindo, N.; Tajiri, T.; Deguchi, H.; Takagi, S.; Miyasaka, H.; Yamashita, M.; Clerac, R.; Coulon, C

    2004-05-01

    Pressure effects on a single chain magnet [Mn{sub 2}(saltmen){sub 2}Ni(pao){sub 2}(py){sub 2}](ClO{sub 4}){sub 2} (saltmen{sup 2-}=N,N'-(1,1,2,2-tetramethylethylene)bis(salicylideneiminate), and pao{sup -}=pyridine-2-aldoximate) have been investigated through AC magnetic measurements under pressure (P). The slow relaxation of the magnetization depends on pressure. Both the blocking temperature (T{sub B}) and energy barrier ({delta}) increase by pressurization, and those enhancements saturate at around P=7 kbar.

  17. Magnetic properties in BaFe12O19 nanoparticles prepared under a magnetic field

    International Nuclear Information System (INIS)

    Wang Jun; Chen Qianwang; Che Shan

    2004-01-01

    It was observed that the nanocrystallites of BaFe 12 O 19 formed at 140 deg. C under a 0.25 T magnetic field exhibited a higher saturation magnetization (6.1 emu/g at room temperature) than that of the sample (1.1 emu/g) obtained under zero magnetic field. Both of the two approaches yielded plain-like particles with an average particle size of 12 nm. However, the Curie temperature (T c ), a direct measuring of the strength of superexchange interaction of Fe 3+ -O 2- -Fe 3+ , increased from 410 deg. C for the nanoparticles prepared without an external field applied to 452 deg. C for the particles formed under a 0.25 T magnetic field, which indicates that external magnetic fields can improve the occupancy of magnetic ions and then increase the superexchange interaction. This was confirmed by electron paramagnetic resonance and Moessbauer spectrum analysis. The results present in this paper suggest that in addition to oxygen defects, surface non-magnetic layer and a fraction of finer particles in the superparamagnetic range, cation vacancies should be responsible for the decreasing of saturation magnetization in magnetic nanoparticles

  18. Synthesis and characterization of robust magnetic carriers for bioprocess applications

    Energy Technology Data Exchange (ETDEWEB)

    Kopp, Willian, E-mail: willkopp@gmail.com [Federal University of São Carlos-UFSCar, Graduate Program in Chemical Engineering, Rodovia Washington Luiz, km 235, São Carlos, São Paulo 13565-905 (Brazil); Silva, Felipe A., E-mail: eq.felipe.silva@gmail.com [Federal University of São Carlos-UFSCar, Graduate Program in Chemical Engineering, Rodovia Washington Luiz, km 235, São Carlos, São Paulo 13565-905 (Brazil); Lima, Lionete N., E-mail: lionetenunes@yahoo.com.br [Federal University of São Carlos-UFSCar, Graduate Program in Chemical Engineering, Rodovia Washington Luiz, km 235, São Carlos, São Paulo 13565-905 (Brazil); Masunaga, Sueli H., E-mail: sueli.masunaga@gmail.com [Department of Physics, Montana State University-MSU, 173840, Bozeman, MT 59717-3840 (United States); Tardioli, Paulo W., E-mail: pwtardioli@ufscar.br [Department of Chemical Engineering, Federal University of São Carlos-UFSCar, Rodovia Washington Luiz, km 235, São Carlos, São Paulo 13565-905 (Brazil); Giordano, Roberto C., E-mail: roberto@ufscar.br [Department of Chemical Engineering, Federal University of São Carlos-UFSCar, Rodovia Washington Luiz, km 235, São Carlos, São Paulo 13565-905 (Brazil); Araújo-Moreira, Fernando M., E-mail: faraujo@df.ufscar.br [Department of Physics, Federal University of São Carlos-UFSCar, Rodovia Washington Luiz, km 235, São Carlos, São Paulo 13565-905 (Brazil); and others

    2015-03-15

    Highlights: • Silica magnetic microparticles were synthesized for applications in bioprocesses. • The process to produce magnetic microparticles is inexpensive and easily scalable. • Microparticles with very high saturation magnetization were obtained. • The structure of the silica magnetic microparticles could be controlled. - Abstract: Magnetic carriers are an effective option to withdraw selected target molecules from complex mixtures or to immobilize enzymes. This paper describes the synthesis of robust silica magnetic microparticles (SMMps), particularly designed for applications in bioprocesses. SMMps were synthesized in a micro-emulsion, using sodium silicate as the silica source and superparamagnetic iron oxide nanoparticles as the magnetic core. Thermally resistant particles, with high and accessible surface area, narrow particle size distribution, high saturation magnetization, and with superparamagnetic properties were obtained. Several reaction conditions were tested, yielding materials with saturation magnetization between 45 and 63 emu g{sup −1}, particle size between 2 and 200 μm and average diameter between 11.2 and 15.9 μm, surface area between 49 and 103 m{sup 2} g{sup −1} and pore diameter between 2 and 60 nm. The performance of SMMps in a bioprocess was evaluated by the immobilization of Pseudomonas fluorescens lipase on to octyl modified SMMp, the biocatalyst obtained was used in the production of butyl butyrate with good results.

  19. Magnetic properties of the magnetic hybrid membranes based on various polymer matrices and inorganic fillers

    International Nuclear Information System (INIS)

    Rybak, Aleksandra; Kaszuwara, Waldemar

    2015-01-01

    Magnetic hybrid membranes based on ethylcellulose (EC), poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) and various magnetic praseodymium and neodymium powder microparticles as fillers were obtained. Permeability, diffusion and sorption coefficients of O 2 , N 2 and synthetic air components were estimated for homogeneous and heterogeneous membranes using the Time Lag method based on constant pressure permeation technique. The microstructure studies and the phase analysis of magnetic membranes were also performed using SEM and XRD. The influence of magnetic parameters, like coercivity, remanence and saturation magnetization of created membranes on the gas transport properties was studied. The results showed that their coercivity depended on composition and microstructure of the magnetic powder. On the other hand, remanence and saturation magnetization increased with the increase of the powder addition in the membrane. It was found that the magnetic membrane's gas transport properties were improved with the increase of membrane's remanence, saturation magnetization and magnetic particle filling. The decrease in powder particle size and associated increase of the membrane's coercivity also positively influenced the gas transport and separation properties of investigated membranes. It was observed that the magnetic ethylcellulose and poly(2,6-dimethyl-1,4-phenylene oxide) membranes had higher gas permeability, while their permselectivity and solubility coefficient values were rather maintained or slightly increased. The results also showed that the magnetic powder content enhanced significantly gas diffusivity in EC and PPO membranes. It was also analyzed the dependence of the drift coefficient w on the magnetic parameters of investigated membranes. The correlation between the membrane selectivity, permeability and magnetic properties with their XRD characteristics was stated. - Highlights: • Membrane's production consisting of EC or PPO polymers and

  20. Magnetic properties of the magnetic hybrid membranes based on various polymer matrices and inorganic fillers

    Energy Technology Data Exchange (ETDEWEB)

    Rybak, Aleksandra, E-mail: Aleksandra.Rybak@polsl.pl [Department of Physical Chemistry and Technology of Polymers, Faculty of Chemistry, Silesian University of Technology, Strzody 9, 44-100 Gliwice (Poland); Kaszuwara, Waldemar [Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, 02-507 Warszawa (Poland)

    2015-11-05

    Magnetic hybrid membranes based on ethylcellulose (EC), poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) and various magnetic praseodymium and neodymium powder microparticles as fillers were obtained. Permeability, diffusion and sorption coefficients of O{sub 2}, N{sub 2} and synthetic air components were estimated for homogeneous and heterogeneous membranes using the Time Lag method based on constant pressure permeation technique. The microstructure studies and the phase analysis of magnetic membranes were also performed using SEM and XRD. The influence of magnetic parameters, like coercivity, remanence and saturation magnetization of created membranes on the gas transport properties was studied. The results showed that their coercivity depended on composition and microstructure of the magnetic powder. On the other hand, remanence and saturation magnetization increased with the increase of the powder addition in the membrane. It was found that the magnetic membrane's gas transport properties were improved with the increase of membrane's remanence, saturation magnetization and magnetic particle filling. The decrease in powder particle size and associated increase of the membrane's coercivity also positively influenced the gas transport and separation properties of investigated membranes. It was observed that the magnetic ethylcellulose and poly(2,6-dimethyl-1,4-phenylene oxide) membranes had higher gas permeability, while their permselectivity and solubility coefficient values were rather maintained or slightly increased. The results also showed that the magnetic powder content enhanced significantly gas diffusivity in EC and PPO membranes. It was also analyzed the dependence of the drift coefficient w on the magnetic parameters of investigated membranes. The correlation between the membrane selectivity, permeability and magnetic properties with their XRD characteristics was stated. - Highlights: • Membrane's production consisting of EC or PPO