These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Explosives detection by nuclear quadrupole resonance (NQR)  

NASA Astrophysics Data System (ADS)

Pure nuclear quadrupole resonance (NQR) of 14N nuclei is quite promising as a method for detecting explosives such as RDX and contraband narcotics such as cocaine and heroin in quantities of interest. Pure NQR is conducted without an external applied magnetic field, so potential concerns about damage to magnetically encoded data or exposure of personnel to large magnetic fields are not relevant. Because NQR frequencies of different compounds are quite distinct, we do not encounter false alarms from the NQR signals of other benign materials. We have constructed a laboratory prototype NQR explosives detector which interrogates a volume of 300 liters (10 ft3). This paper presents abbreviated results from a demonstration of the laboratory prototype NQR explosives detector conducted at the Federal Aviation Administration Technical Center in May 1994 on RDX-based explosives.

Garroway, Allen N.; Buess, Michael L.; Yesinowski, James P.; Miller, Joel B.; Krauss, Ronald A.

1994-10-01

2

Frequency selective detection of nuclear quadrupole resonance (NQR) spin echoes  

NASA Astrophysics Data System (ADS)

Nuclear Quadrupole Resonance (NQR) is a radio frequency (RF) technique that can be used to detect the presence of quadrupolar nuclei, such as the 14N nucleus prevalent in many explosives and narcotics. The technique has been hampered by low signal-to-noise ratios and is further aggravated by the presence of RF interference (RFI). To ensure accurate detection, proposed detectors should exploit the rich form of the NQR signal. Furthermore, the detectors should also be robust to any remaining residual interference, left after suitable RFI mitigation has been employed. In this paper, we propose a new NQR data model, particularly for the realistic case where multiple pulse sequences are used to generate trains of spin echoes. Furthermore, we refine two recently proposed approximative maximum likelihood (AML) detectors, enabling the algorithm to optimally exploit the data model of the entire echo train and also incorporate knowledge of the temperature dependent spin-echo decay time. The AML-based detectors ensure accurate detection and robustness against residual RFI, even when the temperature of the sample is not precisely known, by exploiting the dependencies of the NQR resonant lines on temperature. Further robustness against residual interference is gained as the proposed detector is frequency selective; exploiting only those regions of the spectrum where the NQR signal is expected. Extensive numerical evaluations based on both simulated and measured NQR data indicate that the proposed Frequency selective Echo Train AML (FETAML) detector offers a significant improvement as compared to other existing detectors.

Somasundaram, Samuel D.; Jakobsson, Andreas; Smith, John A. S.; Althoefer, Kaspar A.

2006-05-01

3

Interplane coupling in the superconductor Y2Ba4Cu7O15 as revealed by NQR spin-echo double resonance  

NASA Astrophysics Data System (ADS)

We report a detailed spin-echo double-resonance study of the planar Cu sites in Y2Ba4Cu7O15 above Tc employing nuclear quadrupole resonance (NQR). The experiments directly reveal the coupling between the inequivalent single planes of a double CuO2 plane. The ratio of particular NQR relaxation rates is a measure for the strength of this interplane coupling with respect to the intraplane coupling. This ratio increases with decreasing temperature. Using recent calculations by Millis and Monien, an interplane coupling constant of about 5 meV is deduced.

Stern, R.; Mali, M.; Roos, J.; Brinkmann, D.

1995-12-01

4

NQR Spin--Echo Double Resonance (SEDOR) Study of Interplane Coupling in Y_2Ba_4Cu_7O_15  

NASA Astrophysics Data System (ADS)

We report a detailed spin--echo double resonance study(R. Stern, M. Mali, J. Roos, and D. Brinkmann, Phys. Rev. B 52), (in press). of the planar Cu sites in Y_2Ba_4Cu_7O_15 above Tc employing nuclear quadrupole resonance (NQR). Due to the alternation of YBa_2Cu_3O7 and YBa_2Cu_4O8 blocks in its structure the individual planes of a CuO2 double plane in Y_2Ba_4Cu_7O_15 are inequivalent and hence can separately be monitored by NMR/NQR methods.(R. Stern et al.), Phys. Rev. B 50, 426 (1994), ibid. 51, 15478 (1995). The experiments directly reveal the coupling between the inequivalent single planes of a double CuO2 plane. The ratio of particular NQR relaxation rates is a measure for the strength of this interplane coupling with respect to the intraplane coupling. This ratio increases with decreasing temperature. Using recent calculations by Millis and Monien,(A. J. Millis and H. Monien, cond-mat # 9506088.) an interplane coupling constant of about 5 meV is deduced.

Stern, Raivo

1996-03-01

5

Methyl quantum tunneling and nitrogen-14 NQR NMR studies using a SQUID magnetic resonance spectrometer  

SciTech Connect

Nuclear Magnetic Resonance (NMR) and Nuclear Quadrupole Resonance (NQR) techniques have been very successful in obtaining molecular conformation and dynamics information. Unfortunately, standard NMR and NQR spectrometers are unable to adequately detect resonances below a few megahertz due to the frequency dependent sensitivity of their Faraday coil detectors. For this reason a new spectrometer with a dc SQUID (Superconducting Quantum Interference Device) detector, which has no such frequency dependence, has been developed. Previously, this spectrometer was used to observe {sup 11}B and {sup 27}Al NQR resonances. The scope of this study was increased to include {sup 23}Na, {sup 51}V, and {sup 55}Mn NQR transitions. Also, a technique was presented to observe {sup 14}N NQR resonances through cross relaxation of the nitrogen polarization to adjacent proton spins. When the proton Zeeman splitting matches one nitrogen quadrupoler transition the remaining two {sup 14}N transitions can be detected by sweeping a saturating rf field through resonance. Additionally, simultaneous excitation of two nitrogen resonances provides signal enhancement which helps to connect transitions from the same site. In this way, nitrogen-14 resonances were observed in several amino acids and polypeptides. This spectrometer has also been useful in the direct detection of methyl quantum tunneling splittings at 4.2 K. Tunneling, frequencies of a homologous series of carboxylic acids were measured and for solids with equivalent crystal structures, an exponential correlation between the tunneling frequency and the enthalpy of fusion is observed. This correlation provides information about the contribution of intermolecular interactions to the energy barrier for methyl rotation.

Black, B.E. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley Lab., CA (United States)

1993-07-01

6

Some features of double-resonance detection of 17O NQR in ice  

NASA Astrophysics Data System (ADS)

Proton oxygen-17 double resonance was used to detect the NQR signals of 17O in natural abundance and isotope-enriched ice. When a nonmodulated rf irradiation was applied to a search for the NQR signals, absorptions due to the "solid state effect" which were shifted toward higher frequencies from resonance were detected only in enriched samples. In such circumtances, a saturation phenomenon was observed; at a given frequency (in the vicinity of a resonance) and 17O concentration, the scaling-down factor of the proton signal reaches a characteristic minimum value. The dependence of this value on the 17O concentration indicates that the two spin systems evolve toward a common final spin temperature in the rotating frame, limiting the signal detection to enriched ice. When the NQR irradiation was modulated at a frequency comparable to the dipole-dipole interaction energy between the two nuclear spin systems and applied at resonance, the proton spin temperature evolved to infinity, thus allowing signal detection even at very low concentrations such as the natural abundance of 17O. Distinct signals were detected at 1615 ± 5, 1710 ± 5, and 3320 ± 10 kHz, which yield the quadrupolar parameters e2qQ = 6.42 MHz and ? = 0.924, consistent with a recent report by Brosnon and Edmonds.

Margalit, Yair; Shporer, Mordechai

7

NQR Spin--Echo Double Resonance (SEDOR) Study of Interplane Coupling in Y_2Ba_4Cu_7O_15  

Microsoft Academic Search

We report a detailed spin--echo double resonance study(R. Stern, M. Mali, J. Roos, and D. Brinkmann, Phys. Rev. B 52), (in press). of the planar Cu sites in Y_2Ba_4Cu_7O_15 above Tc employing nuclear quadrupole resonance (NQR). Due to the alternation of YBa_2Cu_3O7 and YBa_2Cu_4O8 blocks in its structure the individual planes of a CuO2 double plane in Y_2Ba_4Cu_7O_15 are inequivalent

Raivo Stern

1996-01-01

8

Two-dimensional NQR using ultra-broadband electronics.  

PubMed

We have recently developed an ultra-broadband instrument that can effectively excite and detect NMR and NQR signals over a wide frequency range. Our current system operates between 100 kHz and 3.2 MHz using an un-tuned sample coil. The major benefits of this instrument compared to conventional NQR/NMR systems include increased robustness, ease of use (in particular for multi-frequency experiments), and elimination of the need for tuning adjustments in the hardware. Here we describe its use for performing two-dimensional (2D) scans, which allow improved interpretation of complex NQR spectra by detecting the connected resonances. Our method relies on population transfers between the three energy levels of spin-1 nuclei (such as (14)N) by using multi-frequency excitation and a single RF coil. Experimental results on pure samples and mixtures are also presented. PMID:24495675

Mandal, S; Song, Y-Q

2014-03-01

9

NQR investigation and characterization of cocrystals and crystal polymorphs  

NASA Astrophysics Data System (ADS)

The application of 14N NQR to the study of cocrystals and crystal polymorphs is reviewed. In ferroelectric and antiferroelectric organic cocrystals 14N NQR is used to determine proton position in an N-H...O hydrogen bond and proton displacement below TC. In cocrystal isonicitinamide - oxalic acid (2:1) 14N NQR is used to distinguish between two polymorphs and to determine the type of the hydrogen bond (N-...H-O). The difference in the 14N NQR spectra of cocrystal formers and cocrystal is investigated in case of carbamazepine, saccharin and carbamazepine - saccharin (1:1). The experimental resolution allows an unambiguous distinction between the 14N NQR spectrum of the cocrystal and the 14N NQR spectra of the cocrystal formers. The possibility of application of NQR and double resonance for the determination of the inhomogeneity of the sample and for the study of the life time of an unstable polymorph is discussed.

Seliger, Janez; Žagar, Veselko; Asaji, Tetsuo

2013-05-01

10

NQR and Raman spectroscopy study of ?-dichlorobiphenyl  

Microsoft Academic Search

Pulsed 0953-8984\\/8\\/21\\/016\\/img9 nuclear quadrupole resonance (NQR) and Raman spectroscopy studies were performed to get information about the structural and dynamic thermal behaviour of the 0953-8984\\/8\\/21\\/016\\/img10 dichlorobiphenyl. NQR measurements of the line-shape and the spin - lattice relaxation time 0953-8984\\/8\\/21\\/016\\/img11 were obtained in the temperature range 80 K - 320 K. Raman spectra from powder samples were recorded for temperatures between

J. Schneider; A. Wolfenson; A. Brunetti; L. A. de O. Nunes

1996-01-01

11

Experiments with Helmholtz Resonators.  

ERIC Educational Resources Information Center

Presents experiments that use Helmholtz resonators and have been designed for a sophomore-level course in oscillations and waves. Discusses the theory of the Helmholtz resonator and resonance curves. (JRH)

Greenslade, Thomas B., Jr.

1996-01-01

12

Intensity of NQR lines for integer spins  

NASA Astrophysics Data System (ADS)

Because of the publication of contradictory information demonstrating an incorrect approach to the modeling of NQR-NMR frequency-intensity spectra of integral-spin isotopes (for example, boron-10), we study the NQR-NMR double resonance with level crossing (DRLC) in10B-1H,11B-1H,59K-1H and23Na-1H in crystal hydrates of sodium tetraborate (Na2B4O7·10H2O) and potassium tetraborate (K2B4O7·4H2O) and the results of the measurements are compared with theoretical calculations. The fact that for a system including three elements-quadrupole (NQR), Zeeman (NMR), and dipole-dipole, which establishes the interaction of the first two- the intensities of the lines in double resonance spectra are determined both by the equations of balance of the populations of the levels of the quadrupole and Zeeman reservoirs and by the probabilities of transitions within each reservoir is taken into account in the calculations. The distortion of the energy levels of the NQR subsystem by the magnetic field in the process of level crossing with the NMR subsystem is taken into account.

Anferov, V. P.; Beloglazov, G. S.; Grechishkin, V. S.

1986-12-01

13

Partial disorder and molecular motion of 4-chlorobiphenyl studied by 35Cl NQR and Raman spectroscopy  

Microsoft Academic Search

Pulsed 35Cl nuclear quadrupole resonance (NQR) and Raman spectroscopy studies were performed to get information about the structural and dynamic thermal behavior of the 4-chlorobiphenyl. NQR measurements of the line shape and the spin-lattice relaxation time (T1) were obtained in the temperature range 80-320 K. An inhomogeneously broadened NQR line shape was observed, suggesting a disordered structure in all the

J. Schneider; A. Wolfenson; C. Schürrer; A. Brunetti; L. A. de O. Nunes

1996-01-01

14

NQR Characteristics of an RDX Plastic Explosives Simulant.  

PubMed

For reliable detection of explosives, a combination of methods integrated within a single measurement platform may increase detection performance. However, the efficient field testing of such measurement platforms requires the use of inexplosive simulants that are detectable by a wide range of methods. Physical parameters such as simulant density, elemental composition and crystalline structure must closely match those of the target explosive. The highly discriminating bulk detection characteristics of nuclear quadrupole resonance (NQR) especially constrain simulant design. This paper describes the development of an inexplosive RDX simulant suited to a wide range of measurement methods, including NQR. Measurements are presented that confirm an RDX NQR response from the simulant. The potential use of the simulant for field testing a prototype handheld NQR-based RDX detector is analyzed. Only modest changes in prototype operation during field testing would be required to account for the use of simulant rather than real explosive. PMID:23204647

Turecek, J; Schwitter, B; Miljak, D; Stancl, M

2012-12-01

15

NMR and NQR studies of quadrupolar effects in glasses and polycrystals with half-integer spins  

NASA Astrophysics Data System (ADS)

NMR and NQR techniques have been used in the present study to investigate glasses and polycrystalline compounds containing nuclei with half-integer spins such as: sp{11}B, sp{23}Na, sp{45}Sc, and sp{93}Nb. The low field ({˜}1.2{-}1.5 Tesla) continuous wave (CW) NMR experiments were performed using the Non-Adiabatic Superfast Passage (NASP) or the slow passage methods. A BRUKER MSL 300 pulsed NMR spectrometer was used for the high field (7.1 Tesla) studies. The CW NQR experiments at room and liquid nitrogen temperature were carried out on a home built Robinson-type spectrometer. Using pulsed NMR the sp{45}Sc response from the glass system CaO-Bsb2Osb3-Scsb2Osb3, yielded a first-order quadrupolar interaction with eta=0 and Qsb{cc}?617 kHz. A new Sc site with Qsb{cc}=23.44 MHz and eta=0 was found in polycrystalline Scsb2Osb3 and it was confirmed by NQR. Employing the NASP method it was found that the fraction of four-coordinated (Nsb4) boron atoms in the alkali thioborate (Nasb2S-Bsb2Ssb3) glass system follows a 3x/(1 - x) relationship for x?0.15, where x is the molar fraction of Nasb2S in the glass. For the NQR spectra the 10% Nasb2S content glass exhibited a broader NQR resonance than the NQR resonance for pure v-Bsb2Ssb3. The additional width was attributed to responses of BSsb3 units whose Qsb{cc} values differ somewhat from the BSsb3 units in the pure vitreous Bsb2Ssb3. The CW NASP method was used to study the sp{23}Na response in the Nasb2O*2SiOsb2 glass, heat treated in three ways: annealed, slow cooled and splat quenched. Subjecting the glass to rapid cooling will produce an increased range of values for the components of the electric field gradient (EFG), and, hence an increased range of values for Qsb{cc} and eta. This was observed for the slow cooled sample when compared with the annealed glass. The effect should be seen also from the slow cooled to the splat quenched sample, but this was not observed. Crystalline sodium disilicate was examined by both NMR and NQR and yielded Qsb{cc} = 1.89 MHz for sp{23}Na and eta=0.9. Furthermore the response from sp{23}Na in the polycrystalline forms of sodium molybdate, sodium tungstate, sodium stanate and albite was examined by means of NASP, pulsed NMR, and NQR. The sp{23}Na spectra for these compounds yielded values of Qsb{cc}, in the range 2.56 MHz to 2.80 MHz. A computer simulation program was used to simulate the spectra of sp{93}Nb-containing compounds. The survey of the niobium response in various polycrystalline compounds using the pulse-echo technique revealed first-order and second-order quadrupolar effects. The sp{93}Nb responses from five glasses in the Nbsb2Osb5-Nasb2O-SiOsb2 ternary glass system produced a second-order quadrupole pattern, but the response might contain more than one Nb site.

Orengo-Aviles, Moises

16

Rapid detection of arsenic minerals using portable broadband NQR  

NASA Astrophysics Data System (ADS)

remote real-time detection of specific arsenic species would significantly benefit in minerals processing to mitigate the release of arsenic into aquatic environments and aid in selective mining. At present, there are no technologies available to detect arsenic minerals in bulk volumes outside of laboratories. Here we report on the first room-temperature broadband 75As nuclear quadrupole resonance (NQR) detection of common and abundant arsenic ores in the Earth crust using a large sample (0.78 L) volume prototype sensor. Broadband excitation aids in detection of natural minerals with low crystallinity. We briefly discuss how the proposed NQR detector could be employed in mining operations.

Lehmann-Horn, J. A.; Miljak, D. G.; O'Dell, L. A.; Yong, R.; Bastow, T. J.

2014-10-01

17

Ultra-Low Temperature Thermometry Using Zeeman Perturbed NQR  

Microsoft Academic Search

We report the results of measurements of the magnetic field perturbed nuclear quadrupole resonance (NQR) lines of powdered Sb immersed in liquid3He at low temperatures. The magnetic field was used to separate the frequencies of the allowed transitions between the \\u000a

E. B. Genio; G. G. Ihas; N. S. Sullivan

1998-01-01

18

115In-NQR study of CeRh1-xIrxIn5 under pressure  

NASA Astrophysics Data System (ADS)

We report on pressure-induced evolutions of antiferromagnetic spin fluctuations (AFM-SFs) and unconventional superconductivity on the x=0.6 sample in a series of compounds CeRh1-xIrxIn5 via the 115In nuclear-quadrupole-resonance (NQR) experiment. The In-NQR 1/T1 measurements have revealed that the slight application of pressure makes Tc=0.9 K at P=0 increase up to Tc=1.06 K at P=0.47 GPa. Concomitantly, the character of AFM-SF evolves from an isotropic regime to an anisotropic one as P increases. These results suggest that AFM-SFs play vital role in mediating the strong-coupling superconductivity in CeRh1-xIrxIn5.

Mugino, Y.; Kawasaki, S.; Yashima, M.; Mukuda, H.; Kitaoka, Y.; Shishido, H.; ?nuki, Y.

2007-03-01

19

The incommensurate phase of 4,4'-dichlorobiphenyl sulphone reinvestigated by 35Cl NQR  

Microsoft Academic Search

In order to acquire new information about the normal-incommensurate (IC) phase transition and to check the existence of a lock-in transition in 4,4'-dichlorobiphenyl sulphone (4,4'-DCBS), a comprehensive 35Cl nuclear quadrupole resonance (NQR) study is reported. Detailed NQR measurements of frequency, line width and spin relaxation time (Tl) were obtained in the temperature range 80-270 K. The results show that the

J. Schneider; A. Wolfenson; A. Brunetti

1994-01-01

20

An analytical method for estimating the {sup 14}N nuclear quadrupole resonance parameters of organic compounds with complex free induction decays for radiation effects studies  

SciTech Connect

The use of {sup 14}N nuclear quadrupole resonance (NQR) as a radiation dosimetry tool has only recently been explored. An analytical method for analyzing {sup 14}N NQR complex free induction decays is presented with the background necessary to conduct pulsed NQR experiments. The {sup 14}N NQR energy levels and possible transitions are derived in step-by-step detail. The components of a pulsed NQR spectrometer are discussed along with the experimental techniques for conducting radiation effects experiments using the spectrometer. Three data analysis techniques -- the power spectral density Fourier transform, state space singular value decomposition (HSVD), and nonlinear curve fitting (using the downhill simplex method of global optimization and the Levenberg-Marquart method) -- are explained. These three techniques are integrated into an analytical method which uses these numerical techniques in this order to determine the physical NQR parameters. Sample data sets of urea and guanidine sulfate data are used to demonstrate how these methods can be employed to analyze both simple and complex free induction decays. By determining baseline values for biologically significant organics, radiation effects on the NQR parameters can be studied to provide a link between current radiation dosimetry techniques and the biological effects of radiation.

Iselin, L.H.

1992-12-31

21

14N NQR and relaxation in ammonium nitrate  

NASA Astrophysics Data System (ADS)

The complete 14N nuclear quadrupole resonance (NQR) spectrum of ammonium nitrate is presented recorded using two double resonance techniques - double contact cross relaxation and zero field NQR. The spectra gave the quadrupole coupling constant (Qcc) and asymmetry parameter (?) values for the nitro of 611 kHz, 0.229 and that for the ammonium nitrogen of 242 kHz, 0.835. The three relaxation transition probabilities have been determined for both the nitro and ammonium nitrogen atoms. The bi-exponential relaxation times (T 1) were measured at 295 K. The values for nitro are 16.9 s and 10.5 s and that of the ammonium are 23.0 s and 16.4 s.

Stephenson, David

2014-11-01

22

Measurement of in-situ stress in salt and rock using NQR techniques  

SciTech Connect

A discussion of how stress and strain affect the quantities which can be measured in an NQR experiment shows that, for stresses of the magnitude to be expected at depths up to about 10,000 feet, quadrupole coupling constants will fall in the range of 1 to 10 kHz for both the sodium and chloride ions in NaCl. The most promising system involves pulsed nuclear double resonance detection; and alterative is to observe the quadrupolar splitting of the NMR signal. Choices to be made in the measurement and mapping techniques are discussed. The well-known perturbation of the homogenous stress field in the neighborhood of a borehole is shown to be advantageous from the point of view of obtaining directional information on the stress. Construction and operation of a borehole stress sensor are considered. The NQR technique seems feasible for measuring the magnitude and direction of underground stress with a resolution of about 25 psi, or 2.5% at 1000 psi. Downhole instrumentation suitable for in-situ determinations of stress appears within the state of the art. Additional tasks required on the project are identified.

Schempp, E.; Hirschfeld, T.; Klainer, S.

1980-12-01

23

Correlation between proton transfer and (35)Cl NQR frequency as well as molecular geometry of chloranilic acid in co-crystals with some organic bases.  

PubMed

Proton transfer in hydrogen-bonded organic co-crystals of chloranilic acid with some organic bases was investigated by nuclear quadrupole resonance (NQR) spectroscopy. The (35)Cl NQR frequencies of chloranilic acid molecule as well as (14)N NQR frequencies of the organic base molecule were measured with the conventional pulse methods as well as double-resonance methods, respectively. The extent of proton transfer in the O...H...N hydrogen bond was estimated from Townes-Dailey analysis of the (14)N NQR parameters. The (35)Cl NQR frequency and molecular geometry of chloranilic acid are correlated to the extent of proton transfer in the protonation process of the organic base molecule. It is shown that the hydrogen bond affects the pi-electron system of chloranilic acid. Geometry dependence of the O...H...N hydrogen bond, i.e. the H-N valence bond order versus the hydrogen-bond geometry correlation is also discussed. PMID:20535777

Asaji, Tetsuo; Seliger, Janez; Zagar, Veselko; Ishida, Hiroyuki

2010-07-01

24

Resonant solar neutrino oscillation experiments  

SciTech Connect

The results of a detailed calculation of the effects of resonant neutrino oscillations in the sun on the current and proposed solar neutrino experiments are presented. Analytic results are used for the electron-neutrino survival probability so that a sophisticated model for both the production distribution of the solar neutrino sources and the solar electron-number density can be employed. Contour plots for the electron-neutrino capture rate, in the mass-difference-squared versus vacuum-mixing-angle plane, are given for the current /sup 37/Cl experiment and the proposed /sup 71/Ga detector.

Parke, S.J.; Walker, T.P.

1986-11-03

25

SQUID detected NMR and NQR  

Microsoft Academic Search

The dc Superconducting QUantum Interference Device (SQUID) is a sensitive detector of magnetic flux, with a typical flux noise of the order 1 ??0 Hz?1\\/2 at liquid helium temperatures. Here ?0=?\\/2e is the flux quantum. In our NMR or NQR spectrometer, a niobium wire coil wrapped around the sample is coupled to a thin film superconducting coil deposited on the

Matthew P. Augustine; Dinh M. TonThat; John Clarke

1998-01-01

26

Copper valence, structural separation and lattice dynamics in tennantite (fahlore): NMR, NQR and SQUID studies  

NASA Astrophysics Data System (ADS)

Electronic and magnetic properties of tennantite subfamily of tetrahedrite-group minerals have been studied by copper nuclear quadrupole resonance (NQR), nuclear magnetic resonance (NMR) and SQUID magnetometry methods. The temperature dependences of copper NQR frequencies and line-width, nuclear spin-lattice relaxation rate T {1/-1} and nuclear spin-echo decay rate T {2/-1} in tennantite samples in the temperature range 4.2-210 K is evidence of the presence of field fluctuations caused by electronic spins hopping between copper CuS3 positions via S2 bridging atom. The analysis of copper NQR data at low temperatures points to the magnetic phase transition near 65 K. The magnetic susceptibility in the range 2-300 K shows a Curie-Weiss behavior, which is mainly determined by Fe2+ paramagnetic substituting ions.

Gainov, R. R.; Dooglav, A. V.; Pen'kov, I. N.; Mukhamedshin, I. R.; Savinkov, A. V.; Mozgova, N. N.

2008-01-01

27

35Cl NQR of an organic ferroelectric phenazine chloranilic acid co-crystal  

NASA Astrophysics Data System (ADS)

A ferroelectric transition of phenazine (Phz) chloranilic acid (H 2ca) co-crystal was studied by 35Cl nuclear quadrupole resonance (NQR). The single NQR line observed at 36.689 MHz at 295 K, split into a doublet below the ferroelectric transition temperature Tc=253 K in accord with the inversion-symmetry breaking at the H 2ca molecular center in the crystal. The continuous variation of the splitting-width through Tc suggests a second-order nature of this phase transition. The NQR frequency is consistent with the crystal structure in which the two acid hydrogen atoms of H 2ca remain as attached to the quinone molecules. The spin-lattice relaxation time T1 showed a decrease with decreasing temperature in the ferroelectric phase. This suggests the existence of a fast motion of nearby atomic group, which is a cause of electric field gradient fluctuation.

Asaji, Tetsuo; Gotoh, Kazuma; Watanabe, Jun

2006-06-01

28

IMPLEMENTATION OF A -NQR SYSTEM AT THE NSCL FOR GROUND STATE QUADRUPOLE MOMENT  

E-print Network

The nuclear electric quadrupole moment, Q, is a direct measure of the nuclear charge distribution, and provides an important test of nuclear structure models. The detected nuclear quadrupole resonance (-NQR, my family, all my teachers and friends iii #12;ACKNOWLEDGMENTS I am very grateful to my advisor

Mantica, Paul F.

29

Gapless superconductivity in overdoped Hg System; Cu-NQR study  

Microsoft Academic Search

The nuclear quadrupole resonance (NQR) investigation of Cu in the overdoped compounds HgBa2CuOy (Hg1201) with y=4. 06 (Tc=92K) and 4.11 (64K) and HgBa2CaCu2Oy (Hg1212) with y=6.13 (Tc=125K) and 6.21 (117K) was carried out in zero field. From the temperature (T) dependence of the nuclear spin-lattice relaxation time, T1, of63Cu, we discuss a cause of the Tc suppression with decreasing the

Shigeki Ohsugi; Tetsuo Tsuchiya; Tadashi Koyama; Kazuo Fueki

1996-01-01

30

NMR/NQR and disorder effects in URu2Si2  

NASA Astrophysics Data System (ADS)

NMR experiments at ambient pressure in URu2Si2 demonstrate a linewidth enhancement effect at the hidden order transition temperature (T0). We find that larger amounts of sample disorder appear to induce larger linewidth enhancement at T0. We will present recent NMR and NQR experiments in oriented powder and single crystal samples of URu2Si2 and discuss the measurements with emphasis on a possible connection between linewidth/disorder effects and hidden order. Both NQR and NMR spectra as functions of temperature and NMR for different magnetic field strengths and orientations will be reported.

Bernal, O. O.; Ishida, K.; Reyes, A. P.; Maclaughlin, D. E.; Lukefarh, H. G.; Mydosh, J. A.; Gortenmulder, T. J.; Amitsuka, H.

2005-03-01

31

Copper NQR and NMR in the superconductor YBa2Cu4O8+x  

Microsoft Academic Search

The frequencies nuQ, the linewidth and the spin-lattice and spin-spin relaxation times T1 and T2, respectively, of the 63Cu nuclear quadrupole resonance (NQR) signals for chain and planar copper sites in YBa2Cu4O8 were measured between 6 and 750 K; in addition nuclear magnetic resonance (NMR) spectra were taken at 150 and 300 K. The results are compared with data known

H. Zimmermann; M. Mali; D. Brinkmann; J. Karpinski; E. Kaldis; S. Rusiecki

1989-01-01

32

Dielectric square resonator investigated with microwave experiments.  

PubMed

We present a detailed experimental study of the symmetry properties and the momentum space representation of the field distributions of a dielectric square resonator as well as the comparison with a semiclassical model. The experiments have been performed with a flat ceramic microwave resonator. Both the resonance spectra and the field distributions were measured. The momentum space representations of the latter evidenced that the resonant states are each related to a specific classical torus, leading to the regular structure of the spectrum. Furthermore, they allow for a precise determination of the refractive index. Measurements with different arrangements of the emitting and the receiving antennas were performed and their influence on the symmetry properties of the field distributions was investigated in detail, showing that resonances with specific symmetries can be selected purposefully. In addition, the length spectrum deduced from the measured resonance spectra and the trace formula for the dielectric square resonator are discussed in the framework of the semiclassical model. PMID:25493860

Bittner, S; Bogomolny, E; Dietz, B; Miski-Oglu, M; Richter, A

2014-11-01

33

75As, 63Cu NMR and NQR characterization of selected arsenic minerals.  

PubMed

The direct measurement and identification of solid state arsenic phases using (75)As NMR is made difficult by the simultaneous conditions of large quadrupole moment and low coordination symmetry in many compounds. However, specific arsenic minerals can efficiently be detected and discriminated via nuclear quadrupolar resonance (NQR). We report on the first NMR and NQR measurements in the natural minerals enargite (Cu3AsS4), niccolite (NiAs), arsenopyrite (FeAsS) and loellingite (FeAs2). The NQR frequencies have been determined from both high-field NMR powder patterns and via zero-field frequency sweeps. Density functional theory (DFT) based ab initio calculations support the experimental results. The compounds studied here are common in terms of the known set of As-containing minerals. They are sometimes encountered in the context of base metal or gold mining. The study represents a significant addition to the list of arsenic minerals that can now be detected with NQR techniques. PMID:23706610

Lehmann-Horn, J A; Miljak, D G; Bastow, T J

2013-01-01

34

A miniaturized NQR spectrometer for a multi-channel NQR-based detection device.  

PubMed

A low frequency (0.5-5 MHz) battery operated sensitive pulsed NQR spectrometer with a transmitter power up to 5 W and a total mass of about 3 kg aimed at detecting (14)N NQR signals, predominantly of illicit materials, was designed and assembled. This spectrometer uses a standard software defined radio (SDR) platform for the data acquisition unit. Signal processing is done with the LabView Virtual instrument on a personal computer. We successfully tested the spectrometer by measuring (14)N NQR signals from aminotetrazole monohydrate (ATMH), potassium nitrate (PN), paracetamol (PCM) and trinitrotoluene (TNT). Such a spectrometer is a feasible component of a portable single or multichannel (14)N NQR based detection device. PMID:25233110

Beguš, Samo; Jazbinšek, Vojko; Pirnat, Janez; Trontelj, Zvonko

2014-10-01

35

Multiband Superconductivity in Filled-Skutterudite Compounds (Pr1-xLax)Os4Sb12: An Sb Nuclear-Quadrupole-Resonance Study  

Microsoft Academic Search

We report on the systematic evolution of normal-state properties and superconducting characteristics in filled-skutterudite compounds (Pr1-xLax)Os4Sb12 determined using Sb nuclear-quadrupole-resonance (NQR) experiments. The Sb-NQR spectra in these compounds have split into two sets, arising from different Sb12 cages containing either Pr or La, which enables us to measure two kinds of nuclear spin-lattice relaxation time T1Pr and T1La. In the

Mamoru Yogi; Takayuki Nagai; Yojyu Imamura; Hidekazu Mukuda; Yoshio Kitaoka; Daisuke Kikuchi; Hitoshi Sugawara; Yuji Aoki; Hideyuki Sato; Hisatomo Harima

2006-01-01

36

127 I and 79 Br NQR spectra of halo-substituted phenols and phenylmercury phenoxides  

Microsoft Academic Search

The full127I NQR spectra of a series of iodo-substituted phenols and phenylmercury phenoxides have been studied. The quadrupole coupling constants and asymmetry parameters have been determined. The character of the OH...Hal hydrogen bond has been found to depend on the nature of substituents in the ring. Correlation dependences of the asymmetry parameters on the sum of the substituents resonance constants

G. K. Semin; S. I. Gushchin; S. B. Karpov; E. V. Bryukhova; L. S. Golovchenko; D. N. Kramov

1996-01-01

37

Low-frequency NMR and NQR with a dc SQUID amplifier  

SciTech Connect

A sensitive Fourier-transform spectrometer based on a dc SQUID (Superconducting QUantum Interference Device) has been developed for the direct detection of nuclear magnetic resonance (NMR) in zero applied magnetic field and pure nuclear quadrupole resonance (NQR) at low frequencies. The motivation to detect zero field NMR and NQR is to provide a new high resolution spectroscopy technique at frequencies below 200 kHz to study ultra-weak interactions in chemicals and materials. By comparing the sensitivity of a SQUID amplifier with that of a conventional semiconductor amplifier, it is shown that a SQUID amplifier is essential for the direct detection of low frequency resonant signals. The spectrometer has a frequency response extending from about 10 to 200 kHz, and a recovery time (after the magnetic pulse is removed) of about 50 {mu}s. The spectrometer is used to detect NMR spectra from Pt and Cu metal powders in a magnetic field of 6 mtesla, and NQR spectra from {sup 2}D in a tunneling methyl group and {sup 14}N in NH{sub 4}ClO{sub 4}. Finally, the zero field NMR spectrum from a quantum tunneling methyl group is calculated. 25 refs., 34 figs., 2 tabs.

Fan, Nong-Qiang.

1990-11-01

38

Electron density distribution in cladribine (2-chloro-2?-deoxyadenosine) - A drug against leukemia and multiple sclerosis - Studied by multinuclear NQR spectroscopy and DFT calculations  

NASA Astrophysics Data System (ADS)

2-Chloro-2'-deoxyadenosine (Cladribine) chemotherapeutic drug has been studied experimentally in solid state by 35Cl NQR and NMR-NQR double resonance and theoretically by the Density Functional Theory. Fifteen resonance frequencies on 14N have been detected and assigned to particular nitrogen sites in the 2-CdA molecule. The effects of tautomerism, regioisomerism, conformations and molecular aggregations, related to intermolecular hydrogen bond formation, on the NQR parameters have been analysed within the DFT and AIM ( Atoms in Molecules) formalism. The properties of the whole molecule, the so-called global reactivity descriptors, have been calculated for a comparison of both syn and anti conformations of 2-CdA molecule to check the effect of crystal packing on molecular conformation.

Latosi?ska, J. N.; Latosi?ska, M.; Seliger, J.; Žagar, V.; Kazimierczuk, Z.

2009-07-01

39

Crystallization and preliminary analysis of the NqrA and NqrC subunits of the Na+-translocating NADH:ubiquinone oxidoreductase from Vibrio cholerae.  

PubMed

The Na+-translocating NADH:ubiquinone oxidoreductase (Na+-NQR) from Vibrio cholerae is a membrane protein complex consisting of six different subunits NqrA-NqrF. The major domains of the NqrA and NqrC subunits were heterologously expressed in Escherichia coli and crystallized. The structure of NqrA1-377 was solved in space groups C222? and P2? by SAD phasing and molecular replacement at 1.9 and 2.1?Å resolution, respectively. NqrC devoid of the transmembrane helix was co-expressed with ApbE to insert the flavin mononucleotide group covalently attached to Thr225. The structure was determined by molecular replacement using apo-NqrC of Parabacteroides distasonis as search model at 1.8?Å resolution. PMID:25005105

Vohl, Georg; Nedielkov, Ruslan; Claussen, Björn; Casutt, Marco S; Vorburger, Thomas; Diederichs, Kay; Möller, Heiko M; Steuber, Julia; Fritz, Günter

2014-07-01

40

Site-directed mutagenesis of conserved cysteine residues in NqrD and NqrE subunits of Na+-translocating NADH:quinone oxidoreductase.  

PubMed

Each of two hydrophobic subunits of Na+-translocating NADH:quinone oxidoreductase (NQR), NqrD and NqrE, contain a pair of strictly conserved cysteine residues within their transmembrane alpha-helices. Site-directed mutagenesis showed that substitutions of these residues in NQR of Vibrio harveyi blocked the Na+-dependent and 2-n-heptyl-4-hydroxyquinoline N-oxide-sensitive quinone reductase activity of the enzyme. However, these mutations did not affect the interaction of NQR with NADH and menadione. It was demonstrated that these conserved cysteine residues are necessary for the correct folding and/or the stability of the NQR complex. Mass and EPR spectroscopy showed that NQR from V. harveyi bears only a 2Fe-2S cluster as a metal-containing prosthetic group. PMID:18298367

Fadeeva, M S; Bertsova, Y V; Verkhovsky, M I; Bogachev, A V

2008-02-01

41

A study of hydrogen bond of imidazole and its 4-nitro derivative by ab initio and DFT calculated NQR parameters  

NASA Astrophysics Data System (ADS)

Nuclear quadrupole resonance (NQR) parameters of 14N, 2H of N 2H groups are calculated for imidazole and 4-nitroimidazole using HF and B3LYP methods. These computations are performed on the basis of X-ray and neutron diffraction structural data which are collected at 100, 103, 123 and 293 K temperatures. In order to take into account intermolecular hydrogen bonds and the van der Waals effects, two different sizes of clusters have been considered. Results of calculation have been compared with that of a single molecule in each case. Calculations illustrate that for imidazole and 4-nitroimidazole octameric and trimeric clusters, respectively, suffice to generate results which are compatible with experimental data. Our calculated NQR parameters and X-ray data show no significant structural change for 4-nitroimidazole at 293 and 100 K.

Amini, S. K.; Hadipour, N. L.; Elmi, F.

2004-06-01

42

Hafnium Resonance Parameter Analysis Using Neutron Capture and Transmission Experiments  

E-print Network

Hafnium Resonance Parameter Analysis Using Neutron Capture and Transmission Experiments M. J factor in reducing the overall uncertainty on reactor physics calculations. Experiments measuring neutron experiments at flight path lengths of 15 and 25 m, respectively. Capture experiments were performed using a 16

Danon, Yaron

43

Hafnium Resonance Parameter Analysis using Neutron Capture and Transmission Experiments  

E-print Network

Hafnium Resonance Parameter Analysis using Neutron Capture and Transmission Experiments Michael J. Experiments measuring neutron capture and transmission were performed at the Rensselaer Polytechnic Institute detectors were used for transmission experiments at flight path lengths of 15 and 25 m. Capture experiments

Danon, Yaron

44

Non-cyclic geometric phase of nuclear quadrupole resonance signals of powdered samples.  

PubMed

The non-cyclic geometric phase of ¹?N and ³?Cl NQR signals induced by the character of trajectory of nuclear magnetization motion upon pulse r.f. excitation of powdered samples is studied. Analytical expressions for the geometric phases of NQR signals of the nuclei of spins I=1 and 3/2 upon nuclear magnetization rotation induced by means of r.f. pulses with frequency detuned from the resonance and for any impulse duration for a separate crystallite are obtained. It is shown that the geometric phase recorded for the signal from a powdered sample at ??=0 can be different from zero and can oscillate upon changes in duration of the r.f. excitation pulse. An alternative variant of the nutation experiment aimed at obtaining the asymmetry parameter ? from locations of frequency singularities in the nutation phase spectrum for nuclei of spin I=3/2 in powder substances is proposed. PMID:21463929

Glotova, O; Ponamareva, N; Sinyavsky, N; Nogaj, B

2011-01-01

45

Nuclear quadrupole resonance of 35Cl nuclei in glassy solution of chlorobenzene in pyridine  

Microsoft Academic Search

Pulsed nuclear quadrupole resonance (NQR) measurements of 35Cl nuclei were performed on 43.5 mol % chlorobenzene solution in pyridine (a) in glassy state (Tg=131 K) after quenching in liquid nitrogen and (b) in crystalline precipitate under slow cooling starting from liquid phase. In both cases the NQR line shape, obtained by the fast Fourier transform (FFT) method, consisted of a

A. E. Wolfenson; A. H. Brunetti; D. J. Pusiol; W. M. Pontuschka

1990-01-01

46

Miniature Magnet for Electron Spin Resonance Experiments  

ERIC Educational Resources Information Center

Describes commercially available permanent magnets that have been incorporated in a compact and inexpensive structure providing both field sweep and modulation suitable for electron spin resonance at microwave frequencies. (MLH)

Rupp, L. W.; And Others

1976-01-01

47

Possibility of valence-fluctuatsion-mediated superconductivity in Cd-doped CeIrIn(5) probed by In NQR.  

PubMed

We report on a pressure-induced evolution of exotic superconductivity and spin correlations in CeIr(In(1-x)Cd(x))(5) by means of in-nuclear-quadrupole-resonance (NQR) studies. Measurements of an NQR spectrum and nuclear-spin-lattice-relaxation rate 1/T(1) have revealed that antiferromagnetism induced by Cd doping emerges locally around Cd dopants, but superconductivity is suddenly induced at T(c)=0.7 and 0.9 K at 2.34 and 2.75 GPa, respectively. The unique superconducting characteristics with a large fraction of the residual density of state at the Fermi level which increases with T(c) differ from those for anisotropic superconductivity mediated by antiferromagnetic correlations. By incorporating the pressure dependence of the NQR frequency pointing to the valence change of Ce, we suggest that unconventional superconductivity in the CeIr(In(1-x)Cd(x))(5) system may be mediated by valence fluctuations. PMID:23005666

Yashima, M; Tagami, N; Taniguchi, S; Unemori, T; Uematsu, K; Mukuda, H; Kitaoka, Y; Ota, Y; Honda, F; Settai, R; Onuki, Y

2012-09-14

48

Nuclear quadrupole resonance study of hydrogen bonded solid materials.  

PubMed

Nuclear quadrupole resonance is presented as a method for the study of solid hydrogen bonded materials. NQR study of hydrogen bonds in ferroelectric and paraelectric KH2PO4, antiferroelectric and paraelectric squaric acid, ferroelectric croconic acid and antiferroelectric and paraelectric cocrystal 5'-dimethyl-2, 2'-bipyridine - chloranilic acid (1:1) are discussed in more details. A 14N NQR study of the strong short O-HKN hydrogen bond in two polymorphic forms of cocrystal isonicotinamide-oxalic acid (2:1) is presented as well. Various correlations between the NQR parameters and between the NQR and structural parameters have been observed. These correlations may be used to determine the proton position in a hydrogen bond and some other structural parameters from the NQR data. PMID:24062106

Seliger, Janez

2011-09-01

49

101Ru NQR study in CeRu 2  

NASA Astrophysics Data System (ADS)

We present measurements of the NQR spectrum and the nuclear spin lattice relaxation rate, 1/ T1, of 101Ru in superconducting CeRu 2 from 1.9 K to 10 K. From the NQR spectrum, the electric quadrupole interaction parameters were determined to be ?Q = 13.2 MHz and ? = 0.1/ T1 varies in proportion to temperature in the normal state, has the Hebel-Slichter coherence peak just below the superconducting transition temperature, TC, of 6.2 K, and decreases exponentially at low temperatures with the energy gap of 2 ? = 4.0 kBTC. 101Ru NQR study indicates that CeRu 2 is an s-wave and strong-coupling superconductor.

Matsuda, K.; Kohori, Y.; Kohara, T.

1996-02-01

50

Narcotics and explosives detection by 14N pure nuclear quadrupole resonance  

NASA Astrophysics Data System (ADS)

Pure nuclear quadrupole resonance (NQR) of 14N nuclei is quite promising as a method for detecting explosives such as RDX and contraband narcotics such as cocaine and heroin in quantities of interest. Pure NQR is conducted without an external applied magnetic field, so potential concerns about damage to magnetically encoded data or exposure of personnel to large magnetic fields are not relevant. Because NQR frequencies of different compounds are quite distinct, we do not encounter false alarms from the NQR signals of other benign materials. We have constructed a proof-of-concept NQR explosives detector which interrogates a volume of 300 liters (10 ft3). With minimal modification to the existing explosives detector, we can detect operationally relevant quantities of (free base) cocaine within the 300-liter inspection volume in 6 seconds. We are presently extending this approach to the detection of heroin base and also examining 14N and 35,37Cl pure NQR for detection of the hydrochloride forms of both materials. An adaptation of this NQR approach may be suitable for scanning personnel for externally carried contraband and explosives. We first outline the basics of the NQR approach, highlighting strengths and weaknesses, and then present representative results for RDX and cocaine detection. We also present a partial compendium of relevant NQR parameters measured for some materials of interest.

Garroway, Allen N.; Buess, Michael L.; Yesinowski, James P.; Miller, Joel B.

1994-03-01

51

Local resonance bandgaps in periodic media: theory and experiment.  

PubMed

Periodic composites such as acoustic metamaterials use local resonance phenomenon in designing low frequency sub-Bragg bandgaps. These bandgaps emerge from a resonant scattering interaction between a propagating wave and periodically arranged resonators. This paper develops a receptance coupling technique to combine the dynamics of the resonator with the unit cell dynamics of the background medium to analyze flexural wave transmission in a periodic structure, involving a single degree of freedom coupling between the medium and the resonator. Receptance techniques allow for a straightforward extension to higher dimensional systems with multiple degrees of freedom coupling and for easier experimental measurements. Closed-form expressions for the location and width of sub-Bragg bandgaps are obtained. Rigid body modes of the unit cell of the background medium are shown to set the bounding frequencies for local resonance bandgaps. Results from the receptance analysis compare well with Bloch wave analysis and experiments performed on a finite structural beam with periodic masses and resonators. Stronger coupling and inertia of the resonator increase the local resonance bandgap width. Two-fold periodicity widens the Bragg bandgap, narrowed by local resonators, thus expanding the design space and highlighting the advantages of hierarchical periodicity. PMID:23967928

Raghavan, L; Phani, A Srikantha

2013-09-01

52

Studies of the electronic structure and biological activity of chosen 1,4-benzodiazepines by 35Cl NQR spectroscopy and DFT calculations  

NASA Astrophysics Data System (ADS)

Selected derivatives of 1,4-benzodiazepine: lorazepam, lormetazepam, oxazepam and temazepam, used as active substances in anxiolytic drugs, have been studied by 35Cl NQR method in order to find the correlation between electronic structure and biological activity. The 35Cl NQR resonance frequencies ( ?Q) measured at 77 K have been correlated with the following parameters characterising their biological activity: biological half-life period ( t0.5), affinity to benzodiazepine receptor (IC 50) and mean dose equivalent. The results of experimental study of some benzodiazepine derivatives by nuclear quadrupole resonance of 35Cl nuclei are compared with theoretical results based on DFT calculations which were carried out by means of Gaussian'98 W software.

Bronisz, K.; Ostafin, M.; Poleshchuk, O. Kh.; Mielcarek, J.; Nogaj, B.

2006-11-01

53

Weak Magnetic Order in Bilayered-Hydrate NaxCoO2\\\\cdotyH2O Structure Probed by Co Nuclear Quadrupole Resonance Proposed Phase Diagram in Superconducting NaxCoO2\\\\cdotyH2O---  

Microsoft Academic Search

A weak magnetic order was found in a nonsuperconducting bilayered-hydrate NaxCoO2\\\\cdotyH2O sample by Co nuclear quadrupole resonance (NQR) measurement. The nuclear spin-lattice relaxation rate divided by temperature 1\\/T_1T shows a prominent peak at 5.5 K, below which a Co NQR peak splits due to an internal field at the Co site. From the analyses of the Co NQR spectrum at

Yoshihiko Ihara; Kenji Ishida; Chishiro Michioka; Masaki Kato; Kazuyoshi Yoshimura; Kazunori Takada; Takayoshi Sasaki; Hiroya Sakurai; Eiji Takayama-Muromachi

2005-01-01

54

1H NMR and 14N NQR study of the ferroelectric phase transition in (CH3)2NH2H2PO4  

Microsoft Academic Search

The ferroelectric phase transition in (CH3)2NH2H2PO4 has been studied by 14N nuclear-quadrupole resonance (NQR) and 1H spin-lattice relaxation. Both above and below TC, the 14N quadrupole coupling constant is approximately 1.2 MHz and the asymmetry parameter eta is close to 1. Two nonequivalent nitrogen positions in the unit cell are observed below TC whereas, above TC, all nitrogen crystallographic positions

J. Seliger; V. Zagar

1998-01-01

55

NUCLEAR SPIN RESONANCE  

Microsoft Academic Search

I. Introduction 566 II. NSR energy levels and frequencies 568 1. Energy levels for resonating nuclei with spins 1 or 3\\/2 568 2. NSR energy levels for spin 5\\/2 571 III. Relative intensities of NSR lines 571 1. Relative intensities of Zeeman components in NQR 571 2. Generalized NSR equations 572 3. Relative intensities of NSR lines for spin 1

Vadim S Grechishkin; N. E. Ajnbinder

1964-01-01

56

Thermal hysteresis in 4,4' dichlorobenzophenone studied by 35Cl NQR  

Microsoft Academic Search

A pulsed NQR study of 4,4' dichlorobenzophenone has been performed to get information about dynamic features in its three crystalline phases. The authors found in phases I (T>190 K) and III (T<180 K) a normal thermal behaviour of the NQR frequency and spin-lattice relaxation time. In the intermediate phase II (180 KNQR parameters could

J. F. Schneider; A. E. Wolfenson; A. H. Brunetti

1992-01-01

57

Hafnium Resonance Parameter Analysis Using Neutron Capture and Transmission Experiments  

SciTech Connect

The focus of this work is to determine the resonance parameters for stable hafnium isotopes in the 0.005 - 200 eV region, with special emphasis on the overlapping {sup 176}Hf and {sup 178}Hf resonances near 8 eV. Accurate hafnium cross sections and resonance parameters are needed in order to quantify the effects of hafnium found in zirconium, a metal commonly used in reactors. The accuracy of the cross sections and the corresponding resonance parameters used in current nuclear analysis tools are rapidly becoming the limiting factor in reducing the overall uncertainty on reactor physics calculations. Experiments measuring neutron capture and transmission are routinely performed at the Rensselaer Polytechnic Institute (RPI) LINAC using the time-of flight technique. {sup 6}Li glass scintillation detectors were used for transmission experiments at flight path lengths of 15 and 25 m, respectively. Capture experiments were performed using a sixteen section NaI multiplicity detector at a flight path length of 25 m. These experiments utilized several thicknesses of metallic and isotope-enriched liquid Hf samples. The liquid Hf samples were designed to provide information on the {sup 176}Hf and {sup 178}Hf contributions to the 8 eV doublet without saturation. Data analyses were performed using the R-matrix Bayesian code SAMMY. A combined capture and transmission data analysis yielded resonance parameters for all hafnium isotopes from 0.005 - 200 eV. Additionally, resonance integrals were calculated, along with errors for each hafnium isotope, using the NJOY and INTER codes. The isotopic resonance integrals calculated were significantly different than previous values. The {sup 176}Hf resonance integral, based on this work, is approximately 73% higher than the ENDF/B-VI value. This is due primarily to the changes to resonance parameters in the 8 eV resonance, the neutron width presented in this work is more than twice that of the previous value. The calculated elemental hafnium resonance integral however, changed very little.

Trbovich, M J; Barry, D P; Slovacek, R E; Danon, Y; Block, R C; Francis, N C; Lubert, M; Burke, J A; Drindak, N J; Lienweber, G; Ballad, R

2007-02-06

58

Superconductivity and Magnetic Fluctuations in Cd2Re2O7 via Cd Nuclear Magnetic Resonance and Re Nuclear Quadrupole Resonance  

Microsoft Academic Search

We report Cd nuclear magnetic resonance (NMR) and Re nuclear quadrupole resonance (NQR) studies on Cd 2Re2O7, the first superconductor among pyrochlore oxides (Tc~=1 K). The Re NQR spectrum at zero magnetic field below 100 K rules out any magnetic or charge order. The spin-lattice relaxation rate below Tc exhibits a pronounced coherence peak and follows the weak-coupling BCS theory

O. Vyaselev; K. Arai; K. Kobayashi; J. Yamazaki; K. Kodama; M. Takigawa; M. Hanawa; Z. Hiroi

2002-01-01

59

Nuclear quadrupole resonance and nuclear magnetic resonance of copper in the high-Tc superconductor YBa2Cu3O7-delta  

Microsoft Academic Search

The 65Cu and 63Cu zero-field nuclear quadrupole resonance (NQR), nuclear magnetic resonance (NMR) at 4.7 and 8.5 T and the spin-lattice relaxation time T1 at 8.5 T are measured in the superconducting oxide YBa2Cu3O7-delta between 80 and 300 K. No sign of magnetic order or localized moments are found. The NQR linewidth is strongly dependent on the oxygen content. We

I. Furo; A. Jánossy; L. Mihály; P. Bánki; I. Pócsik; I. Bakonyi; I. Heinmaa; E. Joon; E. Lippmaa

1987-01-01

60

Hafnium Resonance Parameter Analysis Using Neutron Capture and Transmission Experiments  

SciTech Connect

The focus of this work is to determine resonance parameters for stable hafnium isotopes in the 0.005-200 eV region, with special emphasis on the overlapping {sup 176}Hf and {sup 178}Hf resonances near 8 eV. The large neutron cross section of hafnium, combined with its corrosion resistance and excellent mechanical properties, make it a useful material for controlling nuclear reactions. Experiments measuring neutron capture and transmission were performed at the Rensselaer Polytechnic Institute (RPI) electron linear accelerator (LINAC) using the time of flight method. {sup 6}Li glass scintillation detectors were used for transmission experiments at flight path lengths of 15 and 25 m. Capture experiments were done using a sixteen section NaI(Tl) multiplicity detector at a flight path length of 25 m. These experiments utilized various thicknesses of metallic and isotopically-enriched liquid samples. The liquid samples were designed to provide information on the {sup 176}Hf and {sup 178}Hf contributions to the 8 eV doublet without saturation. Data analysis was done using the R-matrix Bayesian code SAMMY version M6 beta. SAMMY is able to account for experimental resolution effects for each of the experimental setups at the RPI LINAC, and also can correct for multiple scattering effects in neutron capture yield data. The combined capture and transmission data analysis yielded resonance parameters for all hafnium isotopes from 0.005-200 eV. Resonance integrals were calculated along with errors for each hafnium isotope using the NJOY [1] and INTER [2] codes. The isotopic resonance integrals calculated were significantly different than previously published values; however the calculated elemental hafnium resonance integral changed very little.

MJ Trbovich; DP Barry; RE Slovacck; Y Danon; RC Block; JA Burke; NJ Drindak; G Leinweber; RV Ballad

2004-10-13

61

Hafnium Resonance Parameter Analysis using Neutron Capture and Transmission Experiments  

NASA Astrophysics Data System (ADS)

The focus of this work is to determine resonance parameters for stable hafnium isotopes in the 0.005-200 eV region, with special emphasis on the overlapping 176Hf and 178Hf resonances near 8 eV. The large neutron cross section of hafnium, combined with its corrosion resistance and excellent mechanical properties, make it a useful material for controlling nuclear reactions. Experiments measuring neutron capture and transmission were performed at the Rensselaer Polytechnic Institute (RPI) electron linear accelerator (LINAC) using the time of flight method. 6Li glass scintillation detectors were used for transmission experiments at flight path lengths of 15 and 25 m. Capture experiments were done using a sixteen-section NaI(Tl) multiplicity detector at a flight path length of 25 m. These experiments utilized various thicknesses of metallic and isotopically enriched liquid samples. The liquid samples were designed to provide information on the 176Hf and 178Hf contributions to the 8-eV doublet without saturation. Data analysis was done using the R-matrix Bayesian code SAMMY version M6 beta. SAMMY is able to account for experimental resolution effects for each of the experimental setups at the RPI LINAC, and also can correct for multiple scattering effects in neutron capture yield data. The combined capture and transmission data analysis yielded resonance parameters for all hafnium isotopes from 0.005-200 eV. Resonance integrals were calculated along with errors for each hafnium isotope using the NJOY and INTER codes. The isotopic resonance integrals calculated were significantly different than previously published values; however the calculated elemental hafnium resonance integral changed very little.

Trbovich, Michael J.; Barry, Devin P.; Slovacek, Rudy E.; Danon, Yaron; Block, Robert C.; Burke, John A.; Drindak, Noel J.; Leinweber, Greg; Ballad, Robert V.

2005-05-01

62

Nuclear Magnetic Resonance Experiments using Laser-Polarized Noble Gas  

E-print Network

Patrick Teen Chung Wong to The Department of Physics in partial fulfillment of the requirements 2001 #12;c 2001 by Glenn Patrick Teen Chung Wong All rights reserved #12;Advisor: Dr. Ronald Walsworth Author: Glenn Patrick Teen Chung Wong Nuclear Magnetic Resonance Experiments using Laser-Polarized Noble

Walsworth, Ronald L.

63

Magnetic Field Gradient Calibration as an Experiment to Illustrate Magnetic Resonance Imaging  

ERIC Educational Resources Information Center

A nuclear magnetic resonance (NMR) spectroscopy experiment for the undergraduate physical chemistry laboratory is described that encompasses both qualitative and quantitative pedagogical goals. Qualitatively, the experiment illustrates how images are obtained in magnetic resonance imaging (MRI). Quantitatively, students experience the…

Seedhouse, Steven J.; Hoffmann, Markus M.

2008-01-01

64

NMR and NQR investigations of local symmetry in the hidden order phase of URu2Si2  

NASA Astrophysics Data System (ADS)

In order to study local symmetries at the 4e(Si)- and 4d(Ru)-sites above and below hidden order transition temperature TO = 17.5 K in URu2Si2, we have investigated the nuclear quadrupole interaction by 73Ge-nuclear magnetic resonance (NMR) measurement on a 10% 73Ge-substituted sample URu2(Si0.9Ge0.1)2, and by 101Ru-nuclear quadrupole resonance (NQR) measurement on a pure single crystal sample. The present 73Ge-NMR measurements do not give any evidence for change in the local symmetry at 4e-site within experimental accuracy. On the other hand, the precise measurement of 101Ru-NQR frequency has detected an anomaly just below TO as sensitively as the thermal expansion measurement dose. Its temperature dependence shows a linear relation with that of the in-plane lattice parameter, which may be a clue to clarify a modification in microscopic charge distribution at TO.

Mito, T.; Hattori, M.; Motoyama, G.; Sakai, Y.; Koyama, T.; Ueda, K.; Kohara, T.; Yokoyama, M.; Amitsuka, H.

2012-12-01

65

79 Br and 127 I nqr spectra in series of acetylene derivatives  

Microsoft Academic Search

The complete79Br and127I NQR spectra of a number of bromo and iodo derivatives of acetylene were studied for the first time, and the field constants of the NQR frequencies were determined. It was found that the asymmetry parameters in them are low. Changes in the field constants are determined by the competing conjugation of the iodine atom and the corresponding

G. K. Semin; S. A. Petukhov; S. I. Gushchin; I. R. Gol'ding; E. V. Bryukhova; A. M. Sladkov

1983-01-01

66

35 Cl, 79 Br, and 127 I NQR spectra of some halogen-containing organoselenium compounds  

Microsoft Academic Search

1.The35Cl,79Br, and127I NQR spectra of a number of halogen-containing organoselenium compounds were obtained.2.The35Cl NQR frequencies of compounds of type R1R2R3SeCl (Ri=Me, Ph, Cl) are linearly related to the induction constants of the substituentssi.

V. V. Saatsazov; T. L. Khotsyanova; N. N. Magdesieva; S. I. Kuznetsov; I. M. Alymov; R. A. Kyandzhetsian; E. V. Bryukhova

1974-01-01

67

Detecting body cavity bombs with nuclear quadrupole resonance  

NASA Astrophysics Data System (ADS)

Nuclear Quadrupole Resonance (NQR) is a technology with great potential for detecting hidden explosives. Past NQR research has studied the detection of land mines and bombs concealed within luggage and packages. This thesis focuses on an NQR application that has received less attention and little or no publicly available research: detecting body cavity bombs (BCBs). BCBs include explosives that have been ingested, inserted into orifices, or surgically implanted. BCBs present a threat to aviation and secure facilities. They are extremely difficult to detect with the technology currently employed at security checkpoints. To evaluate whether or not NQR can be used to detect BCBs, a computational model is developed to assess how the dielectric properties of biological tissue affect the radio frequency magnetic field employed in NQR (0.5-5MHz). The relative permittivity of some biological tissue is very high (over 1,000 at 1MHz), making it conceivable that there is a significant effect on the electromagnetic field. To study this effect, the low-frequency approximation known as the Darwin model is employed. First, the electromagnetic field of a coil is calculated in free space. Second, a dielectric object or set of objects is introduced, and the free-space electric field is modified to accommodate the dielectric object ensuring that the relevant boundary conditions are obeyed. Finally, the magnetic field associated with the corrected electric field is calculated. This corrected magnetic field is evaluated with an NQR simulation to estimate the impact of dielectric tissue on NQR measurements. The effect of dielectric tissue is shown to be small, thus obviating a potential barrier to BCB detection. The NQR model presented may assist those designing excitation and detection coils for NQR. Some general coil design considerations and strategies are discussed.

Collins, Michael London

68

I: Low Frequency NMR and NQR Using a dc SQUID. II: Variable-temperature 13C CP/MAS of Organometallics  

SciTech Connect

NMR and NQR at low frequencies are difficult prospects due to small nuclear spin polarization. Furthermore, the sensitivity'of the inductive pickup circuitry of standard spectrometers is reduced as the frequency is lowered. I have used a cw-SQUID (Superconducting QUantum Interference Device) spectrometer, which has no such frequency dependence, to study the local atomic environment of {sup 14}N via the quadrupolar interaction. Because {sup 14}N has spin I = 1 and a 0-6 MHz frequency range, it is not possible to obtain well-resolved spectra in high magnetic fields. I have used a technique to observe {sup 14}N NQR resonances via their effect on neighboring protons mediated by the heteronuclear dipolar interaction to study peptides and narcotics. The sensitivity of the SQUID is not enough to measure low-frequency surface (or other low spin density) systems. The application of spin-polarized xenon has been previously used to enhance polarization in conventional NMR experiments. Because xenon only polarizes spins with which it is in contact, it is surface selective. While differences in chemical shifts between surface and bulk spins are not large, it is expected that the differences in quadrupole coupling constant should be very large due to the drastic change of the electric field gradient surrounding spins at the surface. With this in mind, I have taken preliminary steps to measure SQUID detected polarization transfer from Xe to another spin species at 4.2 K and in small magnetic fields (<50 G). In this regime, the spin-lattice relaxation of xenon is dependent on the applied magnetic field. The results of our efforts to characterize the relaxation of xenon are presented. The final section describes the solid-state variable-temperature (VT) one- and two-dimensional {sup 13}C cross polarization (CP)/magic angle spinning (MAS) NMR of Hf({eta}{sup 5}-C{sub 5}H{sub 5}){sub 2}({eta}{sup 1}-C{sub 5}H{sub 5}){sub 2}, Zr({eta}{sup 5}-C{sub 5}H{sub 5}){sub 3}({eta}{sup 1}-C{sub 5}H{sub 5}) and Sn({eta}{sup 1}-C{sub 5}H{sub 5}){sub 4}. This work was undertaken in the hope of gaining insight into the intramolecuhrr dynamics, specifically which fluxional processes exist in the solid state, by what mechanism rearrangements are occurring, and the activation energies by which these processes are governed.

Ziegeweid, M.A.

1995-11-29

69

Closing supersymmetric resonance regions with direct detection experiments  

SciTech Connect

One of the few remaining ways that neutralinos could potentially evade constraints from direct detection experiments is if they annihilate through a resonance, as can occur if 2m{sub ?{sup 0}} falls within about ?10% of either m{sub A/H}, m{sub h}, or m{sub Z}. Assuming a future rate of progress among direct detection experiments that is similar to that obtained over the past decade, we project that within 7 years the light Higgs and Z pole regions will be entirely closed, while the remaining parameter space near the A/H resonance will require that 2m{sub ?{sup 0}} be matched to the central value (near m{sub A}) to within less than 4%. At this rate of progress, it will be a little over a decade before multi-ton direct detection experiments will be able to close the remaining, highly-tuned, regions of the A/H resonance parameter space.

Kelso, Chris [Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112 (United States)

2014-06-24

70

35Cl NQR study of lattice dynamic and magnetic property of a crystalline coordination polymer {CuCA(phz)(H 2O) 2} n  

NASA Astrophysics Data System (ADS)

Copper(II) compounds {CuCA(phz)(H 2O) 2} n (H 2CA = chloranilic acid, phz = phenazine) having a layer structure of -CuCA(H 2O) 2- polymer chains and phenazine were studied by 35Cl nuclear quadrupole resonance (NQR). The single NQR line observed at 35.635 MHz at 261.5 K increased to 35.918 MHz at 4.2 K. The degree of reduction of electric field gradient due to lattice vibrations was similar to that of chloranilic acid crystal. Temperature dependence of spin-lattice relaxation time, T1, of the 35Cl NQR signal below 20 K, between 20 and 210 K, and above 210 K, was explained by (1) a decrease of effective electron-spin density caused by antiferromagnetic interaction, (2) a magnetic interaction between Cl nuclear-spin and electron-spins on paramagnetic Cu(II) ions, and (3) an increasing contribution from reorientation of ligand molecules, respectively. The electron spin-exchange parameter ? J? between the neighboring Cu(II) electrons was estimated to be 0.33 cm -1 from the T1 value of the range 20-210 K. Comparing this value with that of J = -1.84 cm -1 estimated from the magnetic susceptibility, it is suggested that the magnetic dipolar coupling with the electron spins on Cu(II) ions must be the principal mechanism for the 35Cl NQR spin-lattice relaxation of {CuCA(phz)(H 2O) 2} n but a delocalization of electron spin over the chloranilate ligand has to be taken into account.

Gotoh, Kazuma; Terao, Takeshi; Asaji, Tetsuo

2007-01-01

71

Nuclear Acoustic Resonance (NAR) Experiments on AuIn_2  

NASA Astrophysics Data System (ADS)

In NMR experiments on metallic bulk samples, the NMR active volume is reduced because of the skin effect. This not only reduces the signal intensity, but also leads to an inhomogeneous spin tipping over the volume of the sample. The penetration depth in superconducting materials is even smaller. Nuclear acoustic resonance (NAR) offers the possibility to overcome penetration dependent difficulties due to high frequency electromagnetic fields. We applied NAR to the intermetallic compound AuIn_2, which shows several fascinating and unexpected effects at low temperature. In our experiments, 10 MHz sound pulses of 10 ?s duration were applied to the sample via a transducer. These pulses interact with the nuclear spin system over the modulated dynamic field gradients and/or over the internal rf--fields which are generated in the presence of a static external magnetic field. We measured the influence of on-- and off-- resonant sound fields on the pickup signal induced in an NMR coil wound directly on the single crystal sample. We report on the results of these experiments as well as on CW--NAR experiments and on acoustic saturation of NMR.

Ihas, Gary G.; Huebner, M.; Leib, J. W.; Eska, G. W.

1997-03-01

72

Temperature and baric dependence of nuclear quadruple resonance spectra in indium and gallium monoselenides  

NASA Astrophysics Data System (ADS)

Pulsed radiospectroscopy method has been used to study nuclear quadruple resonance (NQR) spectra of 69Ga and 115In isotopes in the layered semiconductors GaSe and InSe. It has been found that in GaSe and InSe there is a considerable temperature dependence of NQR frequency which in the temperature range of 250 to 390 K is practically linear with conversion slope 1.54 kHz/degree for 69Ga and 2.35 kHz/degree for 115In. In the same crystals the effect of uniaxial pressure on NQR spectra applied along the optical axis ? up to the values of 500 kg/?m2 has been studied. A strong attenuation of NQR spectra intensity with increase in pressure on layered crystal package has been established. The unvaried multiplicity of resonance spectra indicates the absence of structural transformations in these layered crystals over the investigated range of temperatures and pressures.

Khandozhko, Victor; Raranskii, Nikolai; Balazjuk, Vitaly; Samila, Andriy; Kovalyuk, Zahar

2013-12-01

73

Experiment study of an electron cyclotron resonant ion source based on a tapered resonance cavity  

SciTech Connect

Electron cyclotron resonant plasma is one type of magnetised plasma generated by continuous microwave energy. It has the property of high degree of ionization and large volume at low gas pressure, which makes it useful for space propulsion and material processing. This article presents the experiment study of the plasma properties and ion beam extraction from an electron cyclotron resonant ion source based on a tapered resonance cavity. Optical emission spectroscopy based on a simple collisional radiation model was used for plasma diagnosis. Experiment results show that, at microwave power setting ranging from 7.06 to 17.40 W and mass flow rate ranging from 1 to 10 sccm, argon gas can be ionized. Ion beam of 109.1 mA from the ion source can be extracted at microwave power of 30 W, mass flow rate of 10 sccm, and accel voltage of 800 V. The diagnosed plasma temperature and density are 2.4–5.2 eV and 2 × 10{sup 16}–4.8 × 10{sup 17} m{sup ?3}, respectively.

Yang, Juan; Shi, Feng; Jin, Yizhou; Wang, Yunmin [College of Astronautics, Northwestern Polytechnic University, Xi'an, Shaanxi 710072 (China)] [College of Astronautics, Northwestern Polytechnic University, Xi'an, Shaanxi 710072 (China); Komurasaki, Kimiya [Department of Aeronautics and Astronautics, The University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo 113-8656 (Japan)] [Department of Aeronautics and Astronautics, The University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo 113-8656 (Japan)

2013-12-15

74

Experiment study of an electron cyclotron resonant ion source based on a tapered resonance cavity  

NASA Astrophysics Data System (ADS)

Electron cyclotron resonant plasma is one type of magnetised plasma generated by continuous microwave energy. It has the property of high degree of ionization and large volume at low gas pressure, which makes it useful for space propulsion and material processing. This article presents the experiment study of the plasma properties and ion beam extraction from an electron cyclotron resonant ion source based on a tapered resonance cavity. Optical emission spectroscopy based on a simple collisional radiation model was used for plasma diagnosis. Experiment results show that, at microwave power setting ranging from 7.06 to 17.40 W and mass flow rate ranging from 1 to 10 sccm, argon gas can be ionized. Ion beam of 109.1 mA from the ion source can be extracted at microwave power of 30 W, mass flow rate of 10 sccm, and accel voltage of 800 V. The diagnosed plasma temperature and density are 2.4-5.2 eV and 2 × 1016-4.8 × 1017 m-3, respectively.

Yang, Juan; Shi, Feng; Jin, Yizhou; Wang, Yunmin; Komurasaki, Kimiya

2013-12-01

75

35Cl nuclear quadrupole resonance study in 4,4'-dichlorobiphenyl sulphone: A possible incommensurate system  

Microsoft Academic Search

Pulsed nuclear quadrupole resonance (NQR) has been used to get information about the nature of the molecular dynamics in two crystalline phases of 4,4'-dichlorobiphenyl sulphone. This work includes detailed experimental measurements of the NQR frequency, spin-lattice relaxation time, and line intensity temperature behavior in the range of temperature where a possible normal-to-incommensurate phase transition occurs. The experimental results show the

D. J. Pusiol; A. E. Wolfenson; A. H. Brunetti

1989-01-01

76

Cyclotron resonance maser experiments in a bifilar helical waveguide Alon Aharony, Rami Drori, and Eli Jerby*  

E-print Network

Cyclotron resonance maser experiments in a bifilar helical waveguide Alon Aharony, Rami Drori 2000 Oscillator and amplifier cyclotron-resonance-maser CRM experiments in a spiral bifilar waveguide, 84.40.Ik, 84.40.Az I. INTRODUCTION Cyclotron resonance masers CRM's and related gyrode- vices

Jerby, Eli

77

Field constants of 79 Br and 127 I NQR of halogen derivatives of carbon  

Microsoft Academic Search

A study has been made of the NQR frequency field constants for the chlorine, bromine, and iodine atoms. It has been shown that the degree to which the field constants are characteristic decreases in the series Cl-Br-I.

S. A. Petukhov; E. V. Bryukhova; G. K. Semin; A. A. Boguslavskii

1984-01-01

78

High Pressure NQR Measurement in CeCu2Si2 up to Sudden Disappearance of Superconductivity  

NASA Astrophysics Data System (ADS)

We report the results of 63Cu nuclear quadrupole resonance (NQR) measurements on CeCu2Si2 under high pressures up to 4.8 GPa. Enhanced spin fluctuations due to quantum criticality at ambient pressure are drastically suppressed with increasing pressure, whereas Tc increases from 0.7 K at ambient pressure to 1.64 K at 4.2 GPa. We have found that bulk superconductivity suddenly disappears at 4.8 GPa accompanied with a rapid decrease in the density of states at the Fermi level. The nuclear spin-lattice relaxation rate 1/T1 at 4.2 GPa reveals that anisotropic superconductivity in the strong-coupling regime is realized even under high pressure far from the antiferromagnetic critical point. Superconductivity under high pressure is unconventional in origin, but the spin fluctuation scenario is not likely to be applicable.

Fujiwara, Kenji; Hata, Yoshiki; Kobayashi, Keigo; Miyoshi, Kiyotaka; Takeuchi, Jun; Shimaoka, Yoshiyuki; Kotegawa, Hisashi; Kobayashi, Tatsuo C.; Geibel, Christoph; Steglich, Frank

2008-12-01

79

Magnetic correlations in La(2-x)Sr(x)CuO4 from NQR relaxation and specific heat  

NASA Technical Reports Server (NTRS)

La-139 and Cu-63 Nuclear Quadrupole Resonance (NQR) relaxation measurements in La(2-x)Sr(x)CuO4 for x ranging from 0 up to 0.3, with particular emphasis on the effect of doping on the Cu(2+) magnetic correlations and dynamics, are reviewed. In the low doping limit, x less than or equal to 0.05, the results can be interpreted consistently in terms of a simple phenomenological 'two-fluids' model whereby the effect of thermally-activated mobile O(2p) holes is the one of disrupting locally the Cu(2+) spin correlations. For x greater than or equal to 0.1, the results indicate the onset, as T approaches T(sub c)(+), of a strong coupling between Cu(2+) spins and the Fermi liquid of O(2p) holes leading to the apparent disappearance of localized Cu(2+) moment in connection with the opening of a superconducting gap.

Borsa, F.; Rigamonti, A.

1991-01-01

80

35 Cl, 79 Br, and 127 I NQR spectra of several polyhalophenols and their phenylmercury derivatives  

Microsoft Academic Search

1.The intramolecular contribution to the splitting of the NQR frequencies in the 2,6-dihalo-4-X-derivatives of phenol has been separated out. The strength of the intramolecular hydrogen bond is substantially dependent on the nature of the substituants in position 4. The splittings in the NQR spectra are reduced upon passing from electron-accepting substituents to electron-donating substituents.2.The intramolecular coordination interactions of mercury atoms

G. Ko Semin; E. V. Bryukhova; D. N. Kravtsov; L. S. Golovchenko

1982-01-01

81

Studies of Ga NMR and NQR in SrGa4  

NASA Astrophysics Data System (ADS)

In order to microscopically investigate the properties in SrGa4, the Ga NMR measurements of a powder sample were carried out. The Ga NMR spectra corresponding to Ga(I) and Ga(II) sites are obtained. The NMR spectra of 69&71Ga (a nuclear spin I = 3/2) in the powder sample of SrGa4 do not take a typical powder pattern caused by the NQR interaction, but take the spectra consisting of three well resolved resonance-lines, which indicates that the nonuniform distribution of crystal orientation in the powder sample occurs because of the magnetic anisotropy. From the analysis of the Ga NMR spectrum, it is found that the ab-plane of the crystal is parallel to the external magnetic field, which would be attributed to the anisotropy of the magnetic susceptibility with the easy axis parallel to the ab-plane. This result is also confirmed by the 69Ga NQR in SrGa4. The Knight shifts of the 69Ga(I) and 69Ga(II) shift slightly to the negative side with decreasing temperature due to the core polarization of the d-electrons. The values of the Knight shift of the 69Ga(I) and 69Ga(II) are 0.01 and -0.11 % at 4.2 K, and 0.09 and -0.08 % at 300 K, respectively. The values of the 1/ T 1 T of the NMR of both 69Ga(I) and 69Ga(II) are almost constant between 4.2 and 100 K, whose values are 1.5 s -1 K -1 at 69Ga(I) and 0.12 s -1 K -1 at 69Ga(II), while the 1/ T 1 T slightly increase above 100K with increasing temperature. The value of T 1 of 69Ga(I) is one order of magnitude less than that of 69Ga(II).

Niki, H.; Higa, N.; Nakamura, S.; Kuroshima, H.; Toji, T.; Yogi, M.; Nakamura, A.; Hedo, M.; Nakama, T.; ?nuki, Y.; Harima, H.

2014-11-01

82

JLAB experiment 01-006: resonance-prime spin structure  

SciTech Connect

Experiment 01-006 (Resonances' Spin Structure) was carried out at Jefferson Lab's Hall C to measure the nucleon spin structure functions in the region of the nucleon resonances. Longitudinally polarized electrons of 5.76 GeV beam energy were incident on solid polarized ammonia and deuterated ammonia (15NH3, 15N2H3) targets. The scattered electrons were detected in the High Momentum Spectrometer parked at a 13.15° angle relative to the beam. The polarized target field was used to align the nucleon spins parallel and perpendicular to the beam helicity to measure the corresponding asymmetries A|| and A^. The measured asymmetries are used to extract in a model-free way the nucleon spin asymmetries A1(W,Q2) and A2(W,Q2), which are functions of the invariant mass of the final system, W, and of the four-momentum transfer, Q2. The measurements extend over 0.8GeV? W?1.95 GeV and are at an average Q2=1.3 [GeV/c]2. Preliminary results are shown, including the world's first set of dat

Rondon-Aramayo, Oscar

2004-11-01

83

Optical Resonators in Current and Future Experiments of the ALPS Collaboration  

NASA Astrophysics Data System (ADS)

The ALPS collaboration runs a "light shining through a wall" (LSW) experiment to search for weakly interacting sub-eV particles (WISPs). Its sensitivity is significantly enhanced by the incorporation of a large-scale production resonator and a small-scale high-power resonant second harmonic generator. Here we report on important experimental details and limitations of these resonators and derive recommendations for further experiments. A very promising improvement for a future ALPS experiment is the incorporation of an additional large-scale regeneration resonator. We present a rough sketch of how to combine a regeneration resonator with a single-photon counter (SPC) as detector for regenerated photons.

Meier, T.

2010-08-01

84

Reviews of Topical Problems: Nuclear Spin Resonance  

Microsoft Academic Search

I. Introduction 566 II. NSR energy levels and frequencies 568 1. Energy levels for resonating nuclei with spins 1 or 3\\/2 568 2. NSR energy levels for spin 5\\/2 571 III. Relative intensities of NSR lines 571 1. Relative intensities of Zeeman components in NQR 571 2. Generalized NSR equations 572 3. Relative intensities of NSR lines for spin 1

Vadim S. Grechishkin; N. E. Ainbinder

1964-01-01

85

Electron cyclotron resonance heating in the microwave tokamak experiment  

NASA Astrophysics Data System (ADS)

This paper presents the results from a series of Electron Cyclotron Resonance Heating (ECRH) experiments on the Microwave Tokamak Experiment (MTX). On-axis heating at B(sub T) = 5T (f(sub ce) = 140 GHz) has been performed at electron densities up to cutoff. We have used both a long-pulse gyrotron (approximately 200 kW, approximately 0.1s) and a pulsed Free Electron Laser (FEL) as microwave sources. Gyrotron experiments with power densities corresponding to 4 MW m(exp -3) are presented. A far infrared (FIR) polarimeter measured peaking of plasma current profiles in some discharges during the ECRH pulse. During high-power single-pulse FEL experiments, single-pass microwave transmission measurements show nonlinear effects (i.e., higher transmission than predicted by linear theory). A corrugated-wall duct was used in the tokamak port to increase the gradient of the parallel refractive index n(sub parallel) of the incident wave, and increased absorption was observed. Evidence of electron tail heating during FEL pulses was observed on soft x-ray and ECE diagnostics. These results are in agreement with predictions of nonlinear theory; extrapolation of this theory to reactor-like conditions indicates efficient absorption and heating. A Laser Assisted Particle Probe Spectroscopy (LAPPS) diagnostic provided estimates of the vacuum electric field of the FEL which were consistent with the measured power. Multiple pulse operation of the ETA-2 accelerator for the FEL has also been demonstrated indicating the feasibility of high-average power FEL operation.

Allen, S. L.; Casper, T. A.; Fenstermacher, M. E.; Foote, J. H.; Hooper, E. B.; Hoshino, K.; Lasnier, C. J.; Lopez, P.; Makowski, M. A.; Marinak, M. M.

1992-09-01

86

Low frequency magnetic resonance with a dc SQUID (Superconducting QUantum Interference Device)  

SciTech Connect

Conventional NMR and NQR spectrometers use transistor-based detectors, which are responsive only to voltage. This forces the experimenter to convert the sample magnetization to a voltage, a process that is less efficient at low frequencies when the Faraday induction effect is used. However, the SQUID directly measures the magnetization, so there is no frequency dependent sensitivity to the sample magnetization. Of course, many other devices also measure magnetic field directly, but none has the low frequency sensitivity of the SQUID. Chapter 2 presents the theory required to extend conventional magnetic resonance to z-axis magnetic resonance, a form most efficient for the SQUID. The operating principles of the SQUID, as well as the techniques used to convert the SQUID response into a useful output voltage, are outlined in Chapter 3. The SQUID spectrometer constructed for these experiments is described in Chapter 4. Also in this chapter are a discussion of the design considerations for a SQUID spectrometer, and indications of the overall performance of our instrument. Experimental results on NQR and low frequency NMR are found in Chapters 5 and 6, respectively. 96 refs., 38 figs., 5 tabs.

Connor, C.

1989-10-01

87

Charge-carrier density and interplane coupling in Y2Ba4Cu7O15: A Cu NMR-NQR study  

NASA Astrophysics Data System (ADS)

We report an observation of the 63,65Cu nuclear quadrupole resonance (NQR) and nuclear magnetic resonance (NMR) in Y2Ba4Cu7O15. We have measured the temperature dependence of the Cu NQR frequency and spin-lattice relaxation at all four chemically inequivalent Cu sites, and of the Cu magnetic shift at two inequivalent plane Cu sites (for the magnetic field parallel and perpendicular to the c axis). The Y2Ba4Cu7O15 compound turns out to be a structure containing two inequivalent CuO2 planes of differing doping levels, a multilattice in which YBa2Cu4O8 blocks and YBa2Cu3O7 blocks alternate. In the normal conducting state both the static and the dynamic electron spin susceptibilities of the individual planes of a double plane are governed by the same temperature dependence, which shows a behavior typical for an underdoped high-Tc compound. The same temperature dependence means strong coupling between these planes, with the lower limit of the coupling constant not much less than 30 meV. Although the planes are strongly coupled, their spin susceptibilities retain a distinct q dependence. The temperature variation of relaxation rate and Knight shift is described in terms of spin-gap formation or, alternatively, of frustrated phase separation. Below Tc, the common temperature dependence is lost, which could arise from the opening of two superconducting gaps that differ in the individual planes.

Stern, R.; Mali, M.; Mangelschots, I.; Roos, J.; Brinkmann, D.; Genoud, J.-Y.; Graf, T.; Muller, J.

1994-07-01

88

Magnetic resonance imaging of the female pelvis: initial experience  

SciTech Connect

The potential of magnetic resonance imaging (MRI) was evaluated in 21 female subjects: seven volunteers, 12 patients scanned for reasons unrelated to the lower genitourinary tract, and two patients referred with gynecologic disease. The uterus at several stages was examined; the premenarcheal uterus (one patient), the uterus of reproductive age (12 patients), the postmenopausal uterus (two patients), and in an 8 week pregnancy (one patient). The myometrium and cyclic endometrium in the reproductive age separated by a low-intensity line (probably stratum basale), which allows recognition of changes in thickness of the cyclic endometrium during the menstrual cycle. The corpus uteri can be distinguished from the cervix by the transitional zone of the isthmus. The anatomic relation of the uterus to bladder and rectum is easily outlined. The vagina can be distinguished from the cervix, and the anatomic display of the closely apposed bladder, vagina, and rectum is clear on axial and coronal images. The ovary is identified; the signal intensity from the ovary depends on the acquisition parameter used. Uterine leiomyoma, endometriosis, and dermoid cyst were depicted, but further experience is needed to ascertain the specificity of the findings.

Hricak, H.; Alpers, C.; Crooks, L.E.; Sheldon, P.E.

1983-12-01

89

NMR and NQR Studies on Non-centrosymmetric Superconductors Re7B3, LaBiPt, and BiPd  

NASA Astrophysics Data System (ADS)

We report the nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements for non-centrosymmetric superconductors Re7B3, LaBiPt, and BiPd containing heavy elements. For all three compounds, the spin--lattice relaxation rate 1/T1 shows a coherence peak just below Tc and decreases exponentially at low temperatures, which indicates that an isotropic superconducting gap is dominant in these compounds. In BiPd, the height of the coherence peak just below Tc is much suppressed, which suggests that there exists a substantial component of gap with nodes in this compound. Our results indicate that heavy element is not the only factor, but the extent of inversion symmetry breaking is also important to induce a large spin--orbit coupling and an unconventional superconducting state.

Matano, Kazuaki; Maeda, Satoki; Sawaoka, Hiroki; Muro, Yuji; Takabatake, Toshiro; Joshi, Bhanu; Ramakrishnan, Srinivasan; Kawashima, Kenji; Akimitsu, Jun; Zheng, Guo-qing

2013-08-01

90

Liquid contact resonance AFM: analytical models, experiments, and limitations  

NASA Astrophysics Data System (ADS)

Contact resonance AFM (CR-AFM) is a scanning probe microscopy technique that utilizes the contact resonances of the AFM cantilever for concurrent imaging of topography and surface stiffness. The technique has not been used in liquid until recently due to analytical and experimental difficulties, associated with viscous damping of cantilever vibrations and fluid loading effects. To address these difficulties, (i) an analytical approach for contact resonances in liquid is developed, and (ii) direct excitation of the contact resonances is demonstrated by actuating the cantilever directly in a magnetic field. By implementing the analytical approach and the direct actuation through magnetic particles, quantitative stiffness imaging on surfaces with a wide range of stiffness can be achieved in liquid with soft cantilevers and low contact forces.

Parlak, Zehra; Tu, Qing; Zauscher, Stefan

2014-11-01

91

1H NMR and 14N NQR study of the ferroelectric phase transition in (CH3)2NH2H2PO4  

NASA Astrophysics Data System (ADS)

The ferroelectric phase transition in (CH3)2NH2H2PO4 has been studied by 14N nuclear-quadrupole resonance (NQR) and 1H spin-lattice relaxation. Both above and below TC, the 14N quadrupole coupling constant is approximately 1.2 MHz and the asymmetry parameter ? is close to 1. Two nonequivalent nitrogen positions in the unit cell are observed below TC whereas, above TC, all nitrogen crystallographic positions are equivalent. Proton spin-lattice relaxation times T1 and T1D show the presence of two molecular motions. Both below and above TC, proton T1 as measured at ?L=32 MHz is dominated by a motion that slows down on the NMR frequency scale below -100 °C. This motion is most probably the 180° reorientation of a dimethylammonium ion around its twofold axis. In the paraelectric phase we observed a slow motion dominating T1D and T1 at low Larmor frequencies. This motion seems to be an up-down reorientation of a dimethylammonium ion along its twofold axis. The NMR and NQR data are interpreted in a model assuming close similarities between the crystal structures of KH2PO4 and (CH3)2NH2H2PO4.

Seliger, J.; Žagar, V.

1998-04-01

92

Effect of substituents on the /sup 35/Cl NQR frequencies of atoms in conditions of hyperconjugation  

SciTech Connect

The authors studied the mechanisms of the change in the NOR spectra in a series of alpha-chloro-substituted dialkyl ethers, organonitrogen compounds, and benzyl and benzylidene chlorides. The NQR spectra were made on a pulsed IS-3 spectrometer at a temperature of 77 degrees K. There are n-o and ..pi..-o interactions which decrease the Cl 35 and Br 79 NQR frequencies in the series of alpha-chloro ethers, alpha-chloroalkylamides, and benzyl halides. The introduction of a geminal halogen atom (dichloromethyl ethers, benzylidene halides) decreases the effect of hyperconjugation.

Arbuzov, B.A.; Andreeva, A.I.; Bredikhin, A.A.; Safin, I.A.; Vereshchagin, A.N.

1985-12-10

93

Nuclear Quadrupole Resonance in Superconducting Gallium  

Microsoft Academic Search

The nuclear quadrupole resonance (NQR) of Ga69 is investigated between 0.8 and 4.2°K. (The super-conducting critical temperature is 1.084°K.) Progressive saturation of the resonance is produced at increasing rf power levels of a frequency-modulated marginal oscillator. The nuclear spin-lattice relaxation rate 1T1 (sec-1) is approximately 12T (°K) in the normal state. The contact part of the hyperfine interaction appears to

R. H. Hammond; W. D. Knight

1960-01-01

94

Superconductivity and Magnetic Fluctuations in Cd2Re2O7 via Cd Nuclear Magnetic Resonance and Re Nuclear Quadrupole Resonance  

NASA Astrophysics Data System (ADS)

We report Cd nuclear magnetic resonance (NMR) and Re nuclear quadrupole resonance (NQR) studies on Cd 2Re2O7, the first superconductor among pyrochlore oxides (Tc~=1 K). The Re NQR spectrum at zero magnetic field below 100 K rules out any magnetic or charge order. The spin-lattice relaxation rate below Tc exhibits a pronounced coherence peak and follows the weak-coupling BCS theory with nearly isotropic energy gap. The results of Cd NMR point to a moderate ferromagnetic enhancement at high temperatures followed by a rapid decrease of the density of states below the structural transition temperature of 200 K.

Vyaselev, O.; Arai, K.; Kobayashi, K.; Yamazaki, J.; Kodama, K.; Takigawa, M.; Hanawa, M.; Hiroi, Z.

2002-06-01

95

Modeling Nonlinear Acoustic Standing Waves in Resonators: Theory and Experiments  

NASA Technical Reports Server (NTRS)

The overall goal of the cooperative research with NASA Glenn is to fundamentally understand, computationally model, and experimentally validate non-linear acoustic waves in enclosures with the ultimate goal of developing a non-contact acoustic seal. The longer term goal is to transition the Glenn acoustic seal innovation to a prototype sealing device. Lucas and coworkers are credited with pioneering work in Resonant Macrosonic Synthesis (RMS). Several Patents and publications have successfully illustrated the concept of Resonant Macrosonic Synthesis. To utilize this concept in practical application one needs to have an understanding of the details of the phenomenon and a predictive tool that can examine the waveforms produced within resonators of complex shapes. With appropriately shaped resonators one can produce un-shocked waveforms of high amplitude that would result in very high pressures in certain regions. Our goal is to control the waveforms and exploit the high pressures to produce an acoustic seal. Note that shock formation critically limits peak-to-peak pressure amplitudes and also causes excessive energy dissipation. Proper shaping of the resonator is thus critical to the use of this innovation.

Raman, Ganesh; Li, Xiaofan; Finkbeiner, Joshua

2004-01-01

96

Electronic properties of Y-Ba-Cu-O superconductors as seen by Cu and O NMR/NQR  

SciTech Connect

Nuclear Magnetic Resonance (NMR) and Nuclear Quadrupole Resonance (NQR) allow the investigation of electronic properties at the atomic level. The authors will report on such studies of typical members of the the Y-Ba-Cu-O family such as YBa2Cu30(6 + x) (1-2-3-(6 + x)), YBa2Cu4O8 (1-2-4) and Y2Ba4Cu7015 (2-4-7) with many examples of recent work performed in their laboratory. In particular, they will deal with Knight shift and relaxation studies of copper and oxygen. They will discuss important issues of current studies such as: (1) Existence of a common electronic spin-susceptibility in the planes (and perhaps in the chains) of 1-2-4; (2) Strong evidence for the existence of a pseudo spin-gap of the antiferromagnetic fluctuations in 1-2-4 and 2-4-7; (3) Evidence for d-wave pairing in 1-2-4; (4) Strong coupling of inequivalent Cu-O planes in 2-4-7 and possible origin for the high Tc value of this compound; and (5) The possibility to describe NMR data in the framework of a charge-excitation picture.

Brinkmann, D.

1995-04-01

97

Electronic properties of Y-Ba-Cu-O superconductors as seen by Cu and O NMR/NQR  

NASA Astrophysics Data System (ADS)

Nuclear Magnetic Resonance (NMR) and Nuclear Quadrupole Resonance (NQR) allow the investigation of electronic properties at the atomic level. We will report on such studies of typical members of the the Y-Ba-Cu-O family such as YBa2Cu30(6 + x) (1-2-3-(6 + x)), YBa2Cu4O8 (1-2-4) and Y2Ba4Cu7015 (2-4-7) with many examples of recent work performed in our laboratory. In particular, we will deal with Knight shift and relaxation studies of copper and oxygen. We will discuss important issues of current studies such as: (1) Existence of a common electronic spin-susceptibility in the planes (and perhaps in the chains) of 1-2-4; (2) Strong evidence for the existence of a pseudo spin-gap of the antiferromagnetic fluctuations in 1-2-4 and 2-4-7; (3) Evidence for d-wave pairing in 1-2-4; (4) Strong coupling of inequivalent Cu-O planes in 2-4-7 and possible origin for the high Tc value of this compound; and (5) The possibility to describe NMR data in the framework of a charge-excitation picture.

Brinkmann, D.

1995-04-01

98

Electronic properties of Y-Ba-Cu-O superconductors as seen by Cu and O NMR/NQR  

NASA Technical Reports Server (NTRS)

Nuclear Magnetic Resonance (NMR) and Nuclear Quadrupole Resonance (NQR) allow the investigation of electronic properties at the atomic level. We will report on such studies of typical members of the the Y-Ba-Cu-O family such as YBa2Cu30(6 + x) (1-2-3-(6 + x)), YBa2Cu4O8 (1-2-4) and Y2Ba4Cu7015 (2-4-7) with many examples of recent work performed in our laboratory. In particular, we will deal with Knight shift and relaxation studies of copper and oxygen. We will discuss important issues of current studies such as: (1) Existence of a common electronic spin-susceptibility in the planes (and perhaps in the chains) of 1-2-4; (2) Strong evidence for the existence of a pseudo spin-gap of the antiferromagnetic fluctuations in 1-2-4 and 2-4-7; (3) Evidence for d-wave pairing in 1-2-4; (4) Strong coupling of inequivalent Cu-O planes in 2-4-7 and possible origin for the high Tc value of this compound; and (5) The possibility to describe NMR data in the framework of a charge-excitation picture.

Brinkmann, D.

1995-01-01

99

Enhanced Doppler Effect in the Upper Hybrid Resonance Microwave Backscattering Experiment  

E-print Network

Enhanced Doppler Effect in the Upper Hybrid Resonance Microwave Backscattering Experiment A, Politekhnicheskaya 26, 194021 St.Petersburg, Russia Observations of enhanced Doppler frequency shift effect based on this effect is proposed. 1. INTRODUCTION Investigation of tokamak plasma poloidal rotation

Paris-Sud XI, Université de

100

Electron Spin Resonance Experiments on Shallow Donors in Germanium  

Microsoft Academic Search

At liquid helium temperatures, spin resonance of localized donor electrons has been observed in phorphorus-, arsenic-, and bismuth-doped germanium. The presence of hyperfine splitting confirms the singlet as the ground state for all three. The separation of the excited triplet states has been measured by uniaxially stressing the samples. The triplet states are all found to lie close to the

D. K. Wilson

1964-01-01

101

Investigation of Wavelet-Based Enhancements to Nuclear Quadrupole Resonance Explosives Detectors  

SciTech Connect

Nuclear Quadrupole Resonance (NQR) is effective for the detection and identification of certain types of explosives such as RDX, PETN and TNT. In explosive detection, the NQR response of certain 14N nuclei present in the crystalline material is probed. The 14N nuclei possess a nuclear quadrupole moment which in the presence of an electric field gradient produces an energy level splitting which may be excited by radio-frequency magnetic fields. Pulsing on the sample with a radio signal of the appropriate frequency produces a transient NQR response which may then be detected. Since the resonant frequency is dependent upon both the quadrupole moment of the 14N nucleus and the nature of the local electric field gradients, it is very compound specific. Under DARPA sponsorship, the authors are using multiresolution methods to investigate the enhancement of operation of NQR explosives detectors used for land mine detection. For this application, NQR processing time must be reduced to less than one second. False alarm responses due to acoustic and piezoelectric ringing must be suppressed. Also, as TNT is the most prevalent explosive found in land mines, NQR detection of TNT must be made practical despite unfavorable relaxation tunes. All three issues require improvement in signal-to-noise ratio, and all would benefit from improved feature extraction. This paper reports some of the insights provided by multiresolution methods that can be used to obtain these improvements. It includes results of multiresolution analysis of experimentally observed NQR signatures for RDX responses and various false alarm signatures in the absence of explosive compounds.

Kercel, Stephen W.; Dress, William B.; Hibbs, Andrew D.; Barrall, Geoffrey A.

1998-06-01

102

35 Cl, 79 Br, 81 Br, and 127 I NQR spectra of organomercury halides  

Microsoft Academic Search

A study of the NQR spectra of some halides disclosed that in the crystals of organomercury halides the behavior of the quadrupole constants is determined to a greater degree by the effect of the nature of the substituants on the intermolecular coordination reactions of Hg... Hal than by the usual transfer of the influence of the electronic effects along the

E. V. Bryukhova; A. K. Prokof'ev; T. Ya. Mel'nikova; O. Yu. Okhlobystia; G. K. Semin

1974-01-01

103

Quantum molecular resonance-assisted phonomicrosurgery: preliminary experience.  

PubMed

The objective of this study was to evaluate the use of quantum molecular resonance (QMR) energy in phonomicrosurgery. Quantum molecular resonance energy (QMRE) is an innovative technology that provides low temperature cutting and coagulation of tissues and causes minimal tissue damage during the procedure. Because of these features, this technology may offer new possibilities in phonomicrosurgery. Twelve patients with vocal fold polyps underwent QMR-assisted phonomicrosurgery. The patients were evaluated before and after surgery at 1 and 3 months postoperatively by using the voice handicap index, laryngeal stroboscopy rating, acoustic voice analysis, and perceptual voice evaluation. The subjects were also evaluated by a patient self-assessment questionnaire at 3 months postoperatively. All parameters significantly improved after QMR-assisted phonomicrosurgery (P < .05). All of the patients also subjectively improved by self-rating. These results suggest that QMRE is a safe and potentially promising treatment in phonomicrosurgery. Yet, further studies should be conducted to confirm these results. PMID:25214549

Demirhan, Erhan; Çukurova, ?brahim; Arslan, ?lker Burak; Ozkan, Elcin Tadihan; Mengi, Erdem; Yigitbasi, Orhan Gazi

2015-01-01

104

Idea Bank: A Resonance Tube Experiment Using "Boomwhackers"  

NSDL National Science Digital Library

Bring the "sound of music" to your science classroom--this activity uses the lengths and fundamental frequencies of a set of resonance tubes to verify the expression for the relationship between these two quantities and the value of the speed of sound. Students blow into one end of the boomwhackers and capture the sound onto a computer. Analysis of the resulting waveform provides an excellent introduction to the mathematical relationships between the musical intervals in a scale.

Michael LoPresto

2005-01-01

105

Experiences with functional magnetic resonance imaging at 1 tesla  

Microsoft Academic Search

Functional magnetic resonance imaging (fMRI) has been performed on a standard 1 T system using a pulse sequence developed to utilize blood oxygen level dependent (BOLD) contrast and an oV-line analysis routine using correlation techniques. The sequence and the data analysis routine have been validated by reproducing the conventional hand movement paradigm studies reported by numerous other workers. Our work

A P JONES; D G HUGHES; D S BRETTLE; L ROBINSON; J R SYKES; Q AZIZ; S HAMDY; D G THOMPSON; S W G DERBYSHIRE; A C N CHEN

1998-01-01

106

The conformational changes induced by ubiquinone binding in the Na+-pumping NADH:ubiquinone oxidoreductase (Na+-NQR) are kinetically controlled by conserved glycines 140 and 141 of the NqrB subunit.  

PubMed

Na(+)-pumping NADH:ubiquinone oxidoreductase (Na(+)-NQR) is responsible for maintaining a sodium gradient across the inner bacterial membrane. This respiratory enzyme, which couples sodium pumping to the electron transfer between NADH and ubiquinone, is not present in eukaryotes and as such could be a target for antibiotics. In this paper it is shown that the site of ubiquinone reduction is conformationally coupled to the NqrB subunit, which also hosts the final cofactor in the electron transport chain, riboflavin. Previous work showed that mutations in conserved NqrB glycine residues 140 and 141 affect ubiquinone reduction and the proper functioning of the sodium pump. Surprisingly, these mutants did not affect the dissociation constant of ubiquinone or its analog HQNO (2-n-heptyl-4-hydroxyquinoline N-oxide) from Na(+)-NQR, which indicates that these residues do not participate directly in the ubiquinone binding site but probably control its accessibility. Indeed, redox-induced difference spectroscopy showed that these mutations prevented the conformational change involved in ubiquinone binding but did not modify the signals corresponding to bound ubiquinone. Moreover, data are presented that demonstrate the NqrA subunit is able to bind ubiquinone but with a low non-catalytically relevant affinity. It is also suggested that Na(+)-NQR contains a single catalytic ubiquinone binding site and a second site that can bind ubiquinone but is not active. PMID:25006248

Strickland, Madeleine; Juárez, Oscar; Neehaul, Yashvin; Cook, Darcie A; Barquera, Blanca; Hellwig, Petra

2014-08-22

107

Peptide backbone orientation and dynamics in spider dragline silk and two-photon excitation in nuclear magnetic and quadrupole resonance  

NASA Astrophysics Data System (ADS)

In the first part of the dissertation, spider dragline silk is studied by solid state NMR techniques. The dependence of NMR frequency on molecular orientation is exploited using the DECODER experiment to determine the orientation of the protein backbone within the silk fibre. Practical experimental considerations require that the silk fibres be wound about a cylindrical axis perpendicular to the external magnetic field, complicating the reconstruction of the underlying orientation distribution and necess-itating the development of numerical techniques for this purpose. A two-component model of silk incorporating static b-sheets and polyglycine II helices adequately fits the NMR data and suggests that the b-sheets are well aligned along the silk axis (20 FWHM) while the helices are poorly aligned (68 FWHM). The effects of fibre strain, draw rate and hydration on orientation are measured. Measurements of the time-scale for peptide backbone motion indicate that when wet, a strain-dependent frac-tion of the poorly aligned component becomes mobile. This suggests a mechanism for the supercontraction of silk involving latent entropic springs that undergo a local strain-dependent phase transition, driving supercontraction. In the second part of this dissertation a novel method is developed for exciting NMR and nuclear quadrupole resonance (NQR) by rf irradiation at multiple frequencies that sum to (or differ by) the resonance frequency. This is fundamentally different than traditional NMR experiments where irradiation is applied on-resonance. With excitation outside the detection bandwidth, two-photon excitation allows for detection of free induction signals during excitation, completely eliminating receiver dead-time. A theoretical approach to describing two-photon excitation is developed based on average Hamiltonian theory. An intuition for two-photon excitation is gained by analogy to the coherent absorption of multiple photons requiring conservation of total energy and momentum. It is shown that two-photon excitation efficiency impro-ves when the two applied rf frequencies deviate from half-resonance. For two-photon NQR, it is shown that observable magnetization appears perpendicular to the excita-tion coil, requiring a second coil for detection, and that double quantum coherences are also generated. Several model systems and experimental geometries are used to demonstrate the peculiarities of two-photon excitation in NMR and NQR.

Eles, Philip Thomas

2005-07-01

108

35 Cl, 79 Br, and 127 I NQR spectra and crystallographic parameters of some halomethylated phosphine oxides  

Microsoft Academic Search

1.The35Cl,79Br, and127I NQR spectra and the crystallographic parameters of a number of halomethylated phosphine oxides were measured.2.A structural nonequivalence of the bromine atoms was detected in (CH2Br)3PO.3.Phase transitions, with a change in the multipleticity of the NQR spectra, were recorded in (CH2Cl)3PO and (CH2I)3PO in the range 77–296°K.

V. V. Saatsazov; T. L. Khotsyanova; S. I. Kuznetsov

1975-01-01

109

Neutron-multiwave-interference experiments with many resonance coils  

SciTech Connect

Neutron-multiwave-interference phenomena based on Ramsey's resonance method of ''separated oscillating fields'' are studied. A neutron passes through N successive resonant coils (({Dirac_h}/2{pi}){omega}{sub 0}=2{mu}{sub n}B{sub 0}), which flip the neutron spin with a probability {rho} smaller than 1. These coils are separated by path lengths L over which a homogeneous field B{sub 1} is present. Because the spin-flip probability {rho} is smaller than 1, the number of waves for a neutron is doubled after each flipper, so as to produce 2{sup N} neutron waves at the end of the setup. The phase difference between any pair of waves is a multiple of a ''phase quantum'' determined by the line integral of the field difference B{sub 1}-B{sub 0} over the length L. Highly regular patterns of the quantum-mechanical probability R in (B{sub 1},{rho}) space appear due to pair interference between individual waves. Possible applications of this phenomenon, such as a direct measurement of n-particle correlation function, are pointed out.

Grigoriev, S. V. [Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg 188350, Russia (Russian Federation); Interfacultair Reactor Instituut, TU-Delft, 2629 JB Delft, The Netherlands (Netherlands); Chetverikov, Yu. O.; Syromyatnikov, A. V. [Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg 188350, Russia (Russian Federation); Kraan, W. H.; Rekveldt, M. Th. [Interfacultair Reactor Instituut, TU-Delft, 2629 JB Delft, The Netherlands (Netherlands)

2003-09-01

110

Magnetic correlations in La(2-x)Sr(x)CuO4 from NQR relaxation and specific heat  

NASA Technical Reports Server (NTRS)

La-139 and Cu-63 Nuclear Quadrupole Resonance (NQR) relaxation measurements in La(2-x)Sr(x)CuO4 for O = to or less than 0.3 and in the temperature range 1.6 + 450 K are analyzed in terms of Cu(++) magnetic correlations and dynamics. It is described how the magnetic correlations that would result from Cu-Cu exchange are reduced by mobile charge defects related to x-doping. A comprehensive picture is given which explains satisfactorily the x and T dependence of the correlation time, of the correlation length and of the Neel temperature T(sub n)(x) as well as being consistent with known electrical resistivity and magnetic susceptibility measurements. It is discussed how, in the superconducting samples, the mobile defects also cause the decrease, for T yields T(sub c)(+) of the hyperfine Cu electron-nucleus effective interaction, leading to the coexistence of quasi-localized, reduced magnetic moments from 3d Cu electrons and mobile oxygen p-hole carriers. The temperature dependence of the effective hyperfine field around the superconducting transition yields an activation energy which could be related to the pairing energy. New specific heat measurements are also presented and discussed in terms of the above picture.

Borsa, F.; Rigamonti, A.

1990-01-01

111

A resonance phenomenon observed in a swept frequency experiment on a mother-daughter ionospheric rocket  

NASA Technical Reports Server (NTRS)

The report presents observations obtained in a swept frequency experiment conducted in a mother-daughter rocket flight at auroral latitudes. The discussion is essentially restricted to the possible interpretation of the experimental signal structures noted at and in the vicinity of a resonance frequency where signal components apparently are generated by nonlinear mechanisms. Various resonance frequencies have been considered in attempts to identify this multichannel response frequency. It is concluded that of all the possibilities invoked, the best consistency is provided by identifying the frequency concerned with the cone resonance frequency demonstrated experimentally in the case of a laboratory plasma by Fisher and Gould (1971).

Folkestad, K.; Troim, J.

1974-01-01

112

Vibrate... Resonate... Quicken the Educational Experience into Intensest Life  

ERIC Educational Resources Information Center

In the quest for more effective education, how can direct personal engagement with actual aesthetic experiences--attendance of performances, participation in artistic workshops and activities, and viewing of actual artworks--play an important role? Art educators have a tremendous opportunity to guide students to engage mind, body, and soul--until…

Chin, Christina

2011-01-01

113

Resonance  

NSDL National Science Digital Library

For advanced undergraduate students: Observe resonance in a collection of driven, damped harmonic oscillators. Vary the driving frequency and amplitude, the damping constant, and the mass and spring constant of each resonator. Notice the long-lived transients when damping is small, and observe the phase change for resonators above and below resonance.

Simulations, Phet I.; Dubson, Michael; Loeblein, Patricia; Olson, Jonathan; Perkins, Kathy; Gratny, Mindy

2011-07-20

114

Resonant scattering experiments with radioactive nuclear beams - Recent results and future plans  

NASA Astrophysics Data System (ADS)

Resonant scattering with low-energy radioactive nuclear beams of E < 5 MeV/u have been studied at CRIB of CNS and at RIPS of RIKEN. As an extension to the present experimental technique, we will install an advanced polarized proton target for resonant scattering experiments. A Monte-Carlo simulation was performed to study the feasibility of future experiments with the polarized target. In the Monte-Carlo simulation, excitation functions and analyzing powers were calculated using a newly developed R-matrix calculation code. A project of a small-scale radioactive beam facility at Kyushu University is also briefly described.

Teranishi, T.; Sakaguchi, S.; Uesaka, T.; Yamaguchi, H.; Kubono, S.; Hashimoto, T.; Hayakawa, S.; Kurihara, Y.; Bihn, D. N.; Kahl, D.; Wakabayashi, Y.; Khiem, L. H.; Cuong, P. V.; Watanabe, S.; Goto, A.

2013-04-01

115

Oleuropein site selective hydrolysis by technomimetic nuclear magnetic resonance experiments.  

PubMed

Technomimetic NMR experiments were performed in accordance with the lye treatment adopted during table olive industrial procedures for the debittering process causing oleuropein degradation. The site selective hydrolysis of the two ester groups, characterizing the biophenolic secoiridoid molecule, was shown to be dependent on the different reactivities of these functionalities. The process is controlled by the experimental conditions exerted on the olive pulp and determined by the buffering capacity of the olive mesocarp and by the epicarp molecular components influencing the reactant penetration into the fruit pulp. The overall hydrolytic process of oleuropein, the bitter principle of olives, using the technomimetic experimental mode, gave rise to its catabolic derivatives, hydroxytyrosol, 11-methyloleoside, and the monoterpene glucoside, technomimetically produced, isolated, and structurally characterized by (1)H, (13)C, and COSY spectroscopy as the oleoside. PMID:10820069

Capozzi, F; Piperno, A; Uccella, N

2000-05-01

116

Subfemtotesla radio-frequency atomic magnetometer for detection of nuclear quadrupole resonance  

E-print Network

Subfemtotesla radio-frequency atomic magnetometer for detection of nuclear quadrupole resonance S 20 November 2006 A radio-frequency tunable atomic magnetometer is developed for detection of nuclearHz 14 N NQR frequency of ammonium nitrate. A potential application of the magnetometer is detection

Romalis, Mike

117

A set of triple-resonance nuclear magnetic resonance experiments for structural characterization of organophosphorus compounds in mixture samples.  

PubMed

The (1)H, (13)C correlation NMR spectroscopy utilizes J(CH) couplings in molecules, and provides important structural information from small organic molecules in the form of carbon chemical shifts and carbon-proton connectivities. The full potential of the (1)H, (13)C correlation NMR spectroscopy has not been realized in the Chemical Weapons Convention (CWC) related verification analyses due to the sample matrix, which usually contains a high amount of non-related compounds obscuring the correlations of the relevant compounds. Here, the results of the application of (1)H, (13)C, (31)P triple-resonance NMR spectroscopy in characterization of OP compounds related to the CWC are presented. With a set of two-dimensional triple-resonance experiments the J(HP), J(CH) and J(PC) couplings are utilized to map the connectivities of the atoms in OP compounds and to extract the carbon chemical shift information. With the use of the proposed pulse sequences the correlations from the OP compounds can be recorded without significant artifacts from the non-OP compound impurities in the sample. Further selectivity of the observed correlations is achieved with the application of phosphorus band-selective pulse in the pulse sequences to assist the analysis of multiple OP compounds in mixture samples. The use of the triple-resonance experiments in the analysis of a complex sample is shown with a test mixture containing typical scheduled OP compounds, including the characteristic degradation products of nerve agents sarin, soman, and VX. The viability of the approach in verification analysis is demonstrated in the analysis of the 30th OPCW Proficiency Test sample. PMID:23084058

Koskela, Harri

2012-11-01

118

Nuclear Quadrupole Resonance Studies of the Sorc Sequence and Nuclear Magnetic Resonance Studies of Polymers  

Microsoft Academic Search

The behavior of induction signals during steady -state pulse irradiation in ^{14} N NQR was investigated experimentally. Because Strong Off-resonance Comb (SORC) signals recur as long as the pulsing continues, very efficient signal-averaging can result. The dependence of these steady-state SORC signals on pulse parameters and on frequency offset are presented, together with a discussion of the applicability of the

Jayakody R. Pemadasa Jayakody

1993-01-01

119

A no-tune no-match wideband probe for nuclear quadrupole resonance spectroscopy in the VHF range  

NASA Astrophysics Data System (ADS)

Nuclear quadrupole resonance (NQR) spectroscopy is a method for the characterization of chemical compounds containing so-called quadrupolar nuclei. Similar to nuclear magnetic resonance (NMR), the sample under investigation is irradiated with strong radiofrequency (RF) pulses, which stimulate the emission of weak RF signals from the quadrupolar nuclei. The signals are then amplified and Fourier transformed so as to obtain a spectrum. In principle, narrowband NQR spectra can be measured with NMR spectrometers. However, pure NQR signals require the absence of a static magnetic field and several special applications require the characterization of a substance over a large bandwidth, e.g. 50–100% of the central frequency, which is hardly possible with standard NMR equipment. Dedicated zero-field NQR equipment is not widespread and current concepts employ resonating probes which are tuned and matched over a wide range by using mechanical capacitors driven by stepper motors. While providing the highest signal to noise ratio (SNR) such probes are slow in operation and can only be operated from dedicated NMR consoles. We developed a low-cost NQR wideband probe without tuning and matching for applications in the very high frequency (VHF) range below 300?MHz. The probe coil was realized as part of a reactive network which approximates an exponential transmission line. The input reflection coefficient of the two developed prototype probe coils is ? 20?dB between 90–145?MHz and 74.5–99.5?MHz, respectively. Two wideband NQR spectra of published test substances were acquired with an SNR of better than 20?dB after sufficient averaging. The measured signals and the SNR correspond very well to the theoretically expected values and demonstrate the feasibility of the method. Because there is no need for tuning and matching, our probes can be operated easily from any available NMR console.

Scharfetter, Hermann; Petrovic, Andreas; Eggenhofer, Heidi; Stollberger, Rudolf

2014-12-01

120

Effect of the oxygen protonation on the electronic structure of urea in the solid state: A 14N NQR study  

NASA Astrophysics Data System (ADS)

The 14N NQR frequencies of urea complexes with H2O2 (1:1), NH4Cl (1:1), oxalic (2:1), phosphoric (1:1), and nitric acid (1:1) at 77 °K are reported. The analysis of the NQR data indicates that the population of the N nonbonding orbital decreases and that the population of the s N-H and N-C bonds increases as the degree of protonation of the O atom of urea increases. These changes are consistent with a larger weight of structures like C = N+H2 as the protonation increases. The NQR results are in agreement with those obtained from a CNDO/2 calculation for the uronioum ion [Yu. A. Panteleev and A. A. Lipovskii, Zhu. Struk. Khim. 17, 2 (1976)].

Murgich, Juan; Santana R., Magaly

1981-04-01

121

Resonance  

NSDL National Science Digital Library

All About Circuits is a website that â??provides a series of online textbooks covering electricity and electronics.â? Written by Tony R. Kuphaldt, the textbooks available here are wonderful resources for students, teachers, and anyone who is interested in learning more about electronics. This specific section, Resonance, is the sixth chapter in the Volume II textbook. Topics covered in this chapter include: electric pendulum, simple parallel resonance, simple series resonance, resonance in series-parallel circuits, and Q and bandwidth of a resonant circuit. Diagrams and detailed descriptions of concepts are included throughout the chapter to provide users with a comprehensive lesson. Visitors to the site are also encouraged to discuss concepts and topics using the All About Circuits discussion forums (registration with the site is required to post materials).

Kuphaldt, Tony R.

122

Low threshold parametric decay backscattering instability in tokamak electron cyclotron resonance heating experiments.  

PubMed

The experimental conditions leading to substantial reduction of the backscattering decay instability threshold in electron cyclotron resonance heating experiments in toroidal devices are analyzed. It is shown that a drastic decrease of threshold is provided by the nonmonotonic behavior of plasma density in the vicinity of magnetic island and poloidal magnetic field inhomogeneity making possible localization of ion Bernstein decay waves. The corresponding ion Bernstein wave gain and the parametric decay instability pump power threshold is calculated. PMID:20867578

Gusakov, E Z; Popov, A Yu

2010-09-10

123

Sinai billiards, Ruelle zeta-functions and Ruelle resonances: microwave experiments  

E-print Network

We discuss the impact of recent developments in the theory of chaotic dynamical systems, particularly the results of Sinai and Ruelle, on microwave experiments designed to study quantum chaos. The properties of closed Sinai billiard microwave cavities are discussed in terms of universal predictions from random matrix theory, as well as periodic orbit contributions which manifest as `scars' in eigenfunctions. The semiclassical and classical Ruelle zeta-functions lead to quantum and classical resonances, both of which are observed in microwave experiments on n-disk hyperbolic billiards.

S. Sridhar; W. T. Lu

2002-06-19

124

DTA and NQR studies of polymorphism in p-chlorofluorobenzene  

Microsoft Academic Search

Differential thermal analysis, and the 35Cl Nuclear Quadrupole Resonance frequency (?Q) and spin-lattice relaxation time (T1) were measured as a function of temperature in p-chlorofluorobenzene. Three different phases were found according to the thermal history of the sample and only one was stable up to the melting point. In one of the phases, the presence of molecular reorientations can be

L. Cerioni; S. Perez; A. Wolfenson

2004-01-01

125

Inhibition of the sodium-translocating NADH-ubiquinone oxidoreductase [Na+-NQR] decreases cholera toxin production in Vibrio cholerae O1 at the late exponential growth phase.  

PubMed

Two virulence factors produced by Vibrio cholerae, cholera toxin (CT) and toxin-corregulated pilus (TCP), are indispensable for cholera infection. ToxT is the central regulatory protein involved in activation of CT and TCP expression. We previously reported that lack of a respiration-linked sodium-translocating NADH-ubiquinone oxidoreductase (Na(+)-NQR) significantly increases toxT transcription. In this study, we further characterized this link and found that Na(+)-NQR affects toxT expression only at the early-log growth phase, whereas lack of Na(+)-NQR decreases CT production after the mid-log growth phase. Such decreased CT production was independent of toxT and ctxB transcription. Supplementing a respiratory substrate, l-lactate, into the growth media restored CT production in the nqrA-F mutant, suggesting that decreased CT production in the Na(+)-NQR mutant is dependent on electron transport chain (ETC) activity. This notion was supported by the observations that two chemical inhibitors, a Na(+)-NQR specific inhibitor 2-n-Heptyl-4-hydroxyquinoline N-oxide (HQNO) and a succinate dehydrogenase (SDH) inhibitor, thenoyltrifluoroacetone (TTFA), strongly inhibited CT production in both classical and El Tor biotype strains of V. cholerae. Accordingly, we propose the main respiratory enzyme of V. cholerae, as a potential drug target to treat cholera because human mitochondria do not contain Na(+)-NQR orthologs. PMID:24361395

Minato, Yusuke; Fassio, Sara R; Reddekopp, Rylan L; Häse, Claudia C

2014-01-01

126

Selective excitation of single and multiple quantum transitions for spin 7/2 in NQR  

NASA Astrophysics Data System (ADS)

The dynamics of spin 7/2 in pure NQR is considered. The orientation of the applied RF field is assumed arbitrary and ? ? 0. For this situation various selective pulses are considered and analytical results obtained. Shaped pulses are also treated. A key feature of this work is to construct the interaction representation from which an analytical calculation, using the computer program 'Maple', can be obtained in a tractable form. The results presented are general for all half integer spins of magnitude higher than 1/2.

Ageev, S. Z.; Sanctuary, B. C.

127

Roles of the Sodium-Translocating NADH:Quinone Oxidoreductase (Na+-NQR) on Vibrio cholerae Metabolism, Motility and Osmotic Stress Resistance  

PubMed Central

The Na+ translocating NADH:quinone oxidoreductase (Na+-NQR) is a unique respiratory enzyme catalyzing the electron transfer from NADH to quinone coupled with the translocation of sodium ions across the membrane. Typically, Vibrio spp., including Vibrio cholerae, have this enzyme but lack the proton-pumping NADH:ubiquinone oxidoreductase (Complex I). Thus, Na+-NQR should significantly contribute to multiple aspects of V. cholerae physiology; however, no detailed characterization of this aspect has been reported so far. In this study, we broadly investigated the effects of loss of Na+-NQR on V. cholerae physiology by using Phenotype Microarray (Biolog), transcriptome and metabolomics analyses. We found that the V. cholerae ?nqrA-F mutant showed multiple defects in metabolism detected by Phenotype Microarray. Transcriptome analysis revealed that the V. cholerae ?nqrA-F mutant up-regulates 31 genes and down-regulates 55 genes in both early and mid-growth phases. The most up-regulated genes included the cadA and cadB genes, encoding a lysine decarboxylase and a lysine/cadaverine antiporter, respectively. Increased CadAB activity was further suggested by the metabolomics analysis. The down-regulated genes include sialic acid catabolism genes. Metabolomic analysis also suggested increased reductive pathway of TCA cycle and decreased purine metabolism in the V. cholerae ?nqrA-F mutant. Lack of Na+-NQR did not affect any of the Na+ pumping-related phenotypes of V. cholerae suggesting that other secondary Na+ pump(s) can compensate for Na+ pumping activity of Na+-NQR. Overall, our study provides important insights into the contribution of Na+-NQR to V. cholerae physiology. PMID:24811312

Minato, Yusuke; Halang, Petra; Quinn, Matthew J.; Faulkner, Wyatt J.; Aagesen, Alisha M.; Steuber, Julia; Stevens, Jan F.; Häse, Claudia C.

2014-01-01

128

Roles of the sodium-translocating NADH:quinone oxidoreductase (Na+-NQR) on vibrio cholerae metabolism, motility and osmotic stress resistance.  

PubMed

The Na+ translocating NADH:quinone oxidoreductase (Na+-NQR) is a unique respiratory enzyme catalyzing the electron transfer from NADH to quinone coupled with the translocation of sodium ions across the membrane. Typically, Vibrio spp., including Vibrio cholerae, have this enzyme but lack the proton-pumping NADH:ubiquinone oxidoreductase (Complex I). Thus, Na+-NQR should significantly contribute to multiple aspects of V. cholerae physiology; however, no detailed characterization of this aspect has been reported so far. In this study, we broadly investigated the effects of loss of Na+-NQR on V. cholerae physiology by using Phenotype Microarray (Biolog), transcriptome and metabolomics analyses. We found that the V. cholerae ?nqrA-F mutant showed multiple defects in metabolism detected by Phenotype Microarray. Transcriptome analysis revealed that the V. cholerae ?nqrA-F mutant up-regulates 31 genes and down-regulates 55 genes in both early and mid-growth phases. The most up-regulated genes included the cadA and cadB genes, encoding a lysine decarboxylase and a lysine/cadaverine antiporter, respectively. Increased CadAB activity was further suggested by the metabolomics analysis. The down-regulated genes include sialic acid catabolism genes. Metabolomic analysis also suggested increased reductive pathway of TCA cycle and decreased purine metabolism in the V. cholerae ?nqrA-F mutant. Lack of Na+-NQR did not affect any of the Na+ pumping-related phenotypes of V. cholerae suggesting that other secondary Na+ pump(s) can compensate for Na+ pumping activity of Na+-NQR. Overall, our study provides important insights into the contribution of Na+-NQR to V. cholerae physiology. PMID:24811312

Minato, Yusuke; Fassio, Sara R; Kirkwood, Jay S; Halang, Petra; Quinn, Matthew J; Faulkner, Wyatt J; Aagesen, Alisha M; Steuber, Julia; Stevens, Jan F; Häse, Claudia C

2014-01-01

129

Instrument for in-situ orientation of superconducting thin-film resonators used for electron-spin resonance experiments  

E-print Network

When used in Electron-Spin Resonance (ESR) measurements, superconducting thin-film resonators must be precisely oriented relative to the external magnetic field in order to prevent the trapping of magnetic flux and the associated degradation of resonator performance. We present a compact design solution for this problem that allows in-situ control of the orientation of the resonator at cryogenic temperatures. Tests of the apparatus show that when proper alignment is achieved, there is almost no hysteresis in the field dependence of the resonant frequency.

Mowry, Andrew; Kuabsek, James; Friedman, Jonathan R

2015-01-01

130

PiC simulations of the anomalous Doppler resonance for a scaled laboratory experiment  

NASA Astrophysics Data System (ADS)

The anomalous Doppler resonance occurs due to coupling between a negative harmonic of the electron cyclotron frequency and an electromagnetic wave, as such this regime is only applicable in slow-wave media like a plasma or dielectric loaded waveguide. In nuclear fusion devices the generation of fast electrons by Lower Hybrid Current Drive or in extreme cases Dreicer acceleration, can lead to the criterion for the anomalous Doppler resonance being fulfilled. The anomalous Doppler resonance is also relevant in the nature of pulsar radio emission. Simulations have been developed to study non-thermal electrons drifting at relativistic velocities along a magnetic field with a background plasma acting as the slow-wave media. The simulations will be used to inform the design of a scaled laboratory experiment at Strathclyde, the results of which will be used to compare with the prediction of the numerical simulations and analytical theory. Once benchmarked by the experiment simulations will investigate regimes relevant to tokamak and astrophysical plasmas.

Bryson, R.; Spiers, D. C.; King, M.; Phelps, A. D. R.; McConville, S. L.; Gillespie, K. M.; Ronald, K.; Vorgul, I.; Cairns, R. A.; Bingham, R.

2012-10-01

131

Effects of nonsinusoidal character of atomic modulation on NQR spin-lattice relaxation time of incommensurate phases  

Microsoft Academic Search

The present work is an extention of the theoretical calculation developed by Blinc to explain the temperature and frequency dependence of the spin-lattice relaxation time in incommensurate phases. We have evaluated the influence of the nonsinusoidal character of the atomic modulation, in the linear approximation, over the NQR spectra and over the spin-lattice relaxation due to direct and Raman processes.

Silvina C. Pérez; Clemar Schurrer; Alberto Wolfenson

2001-01-01

132

Experiment on bias stability measurement of resonator fiber optic gyro with digital feedback scheme  

NASA Astrophysics Data System (ADS)

Experiment on bias stability measurement of resonator fiber optic gyro with a newly developed digital feedback scheme is performed and a sensitivity of 5.6×10-4 rad/s is demonstrated. Under the digital control scheme, the short term and long term laser central frequency drift are reduced by the output of a fast loop determined by proportional calculation to the order of several least significant bits (LSBs) and the output of a slow loop decided by an up/down counter, respectively. Resettling pulse noise due to imperfect 2? voltage of the hybrid digital serrodyne phase modulation waveform is also reduced by automatic proportional and integration (PI) control. Besides, polarization noise is suppressed by exciting single eigen state of polarization (ESOP) of the resonator with twice 90 degree polarization-axis rotated splicing.

Wang, Xijing; He, Zuyuan; Hotate, Kazuo

2009-10-01

133

Ru-NQR Study for Novel Phase Transition in CeRu2Al10  

NASA Astrophysics Data System (ADS)

We have performed Ru-NQR measurements on CeRu2Al10 exhibiting novel phase transition at an abnormally high temperature T0 = 27.3 K and on NdRu2Al10 with a magnetic transition temperature Tm = 2.4 K as a reference RKKY system. The splitting of the NQR line due to internal fields below T0 shows a mean-field-like monotonic increase, indicating no change in the magnetic structure below T0. The internal field strength is one order larger than those at Al sites in CeRu2Al10, and is comparable to that at the Ru site in NdRu2Al10 despite the sevenfold smaller magnitude of the 4f moment, being indicative of an enhanced conduction electron polarization at the Ru site. One of the causes of the high T0 might be the enhanced exchange coupling through the Ce–Ru–Ce path mediated by the enhanced conduction electron polarization. Being similar to that in the Al site, the nuclear spin–lattice relaxation rate 1/T1 shows a gap-like decrease below T0 without enhancement owing to a critical slowing down at T0, in contrast to the mean field 2nd-order transition.

Matsumura, Masahiro; Tomita, Naoya; Matsuoka, Junichirou; Kishimoto, Yasuki; Kato, Harukazu; Kitagawa, Kentaro; Nishioka, Takashi; Tanida, Hiroshi; Sera, Masafumi

2014-10-01

134

A tapered undulator experiment at the ELBE far infrared hybrid-resonator oscillator free electron laser  

NASA Astrophysics Data System (ADS)

A tapered undulator experiment was carried out at the ELBE far-infrared free electron laser (FEL). The oscillator FEL makes use of a hybrid optical resonator. The main motivation was to see whether the presence of a dispersive medium in the form of a waveguide in the resonator has any effect on the outcome. The FEL saturated power and the wavelength shifts have been measured as a function of both positive as well as negative undulator field amplitude tapering. In contrast to the typical high-gain FELs where positive tapering proves beneficial for the output power we observed an improvement of performance at negative taper. During the same experiments we studied the characteristics of the detuning curves. The width of the curves indicates a maximum small signal gain for zero taper while the output peak power increases with negative taper. The saturated power output, the detuning curve characteristics, and the wavelength shifts agrees with the theoretical predictions. Details of the experiment are presented.

Asgekar, V.; Lehnert, U.; Michel, P.

2012-01-01

135

A Mutation in Na(+)-NQR Uncouples Electron Flow from Na(+) Translocation in the Presence of K(+).  

PubMed

The sodium-pumping NADH:ubiquinone oxidoreductase (Na(+)-NQR) is a bacterial respiratory enzyme that obtains energy from the redox reaction between NADH and ubiquinone and uses this energy to create an electrochemical Na(+) gradient across the cell membrane. A number of acidic residues in transmembrane helices have been shown to be important for Na(+) translocation. One of these, Asp-397 in the NqrB subunit, is a key residue for Na(+) uptake and binding. In this study, we show that when this residue is replaced with asparagine, the enzyme acquires a new sensitivity to K(+); in the mutant, K(+) both activates the redox reaction and uncouples it from the ion translocation reaction. In the wild-type enzyme, Na(+) (or Li(+)) accelerates turnover while K(+) alone does not activate. In the NqrB-D397N mutant, K(+) accelerates the same internal electron transfer step (2Fe-2S ? FMNC) that is accelerated by Na(+). This is the same step that is inhibited in mutants in which Na(+) uptake is blocked. NqrB-D397N is able to translocate Na(+) and Li(+), but when K(+) is introduced, no ion translocation is observed, regardless of whether Na(+) or Li(+) is present. Thus, this mutant, when it turns over in the presence of K(+), is the first, and currently the only, example of an uncoupled Na(+)-NQR. The fact the redox reaction and ion pumping become decoupled from each other only in the presence of K(+) provides a switch that promises to be a useful experimental tool. PMID:25486106

Shea, Michael E; Mezic, Katherine G; Juárez, Oscar; Barquera, Blanca

2015-01-20

136

Strong coupling between antiferromagnetic and superconducting order parameters of CeRhIn5 studied by I115n nuclear quadrupole resonance spectroscopy  

Microsoft Academic Search

We report on a pressure (P) -induced evolution of magnetism and superconductivity (SC) in a helical magnet CeRhIn5 with an incommensurate wave vector Qi=((1)\\/(2),(1)\\/(2),0.297) through the I115n nuclear quadrupole resonance (NQR) measurements under P . Systematic measurements of the I115n -NQR spectrum reveal that the commensurate antiferromagnetism (AFM) with Qc=((1)\\/(2),(1)\\/(2),(1)\\/(2)) is realized above Pm˜1.7GPa . An important finding is that

M. Yashima; H. Mukuda; Y. Kitaoka; H. Shishido; R. Settai; Y. Onuki

2009-01-01

137

M dependence in the analysis of NH3-He microwave double resonance experiments  

NASA Technical Reports Server (NTRS)

New close-coupled calculations of laboratory-frame, m-dependent cross sections for rotational excitation in NH3-He collisions are used to examined the validity of using degeneracy averaged values in the analysis of four-level double resonance experiments. It is found that the proper use of m-dependent cross sections and absorption probabilities produces only minor changes in the calculated Delta I/I (the fractional change in the signal absorption intensity when pumping radiation is applied) and does not, therefore, resolve the discrepancies between theoretical and experimental values that were noted in previous studies.

Davis, S. L.; Green, S.

1983-01-01

138

First results of an auxiliary electron cyclotron resonance heating experiment in the GDT magnetic mirror  

NASA Astrophysics Data System (ADS)

The axially symmetric magnetic mirror device gas-dynamic trap (GDT, Budker Institute, Novosibirsk) has recently demonstrated a tangible increase in plasma electron temperature. According to laser scattering, a value of 0.4 keV has been achieved (a twofold increase). In addition to standard machine operation, utilizing a 5 MW neutral beam injection, a newly installed electron cyclotron resonance heating (ECRH) system was employed (54.5 GHz, 0.4 MW). The reported progress in electron temperature, along with previous experiments, which demonstrated plasma confinement at beta as high as 60%, is a significant advancement towards an energy efficient fusion neutron source based on GDT physics.

Bagryansky, P. A.; Kovalenko, Yu. V.; Savkin, V. Ya.; Solomakhin, A. L.; Yakovlev, D. V.

2014-08-01

139

Variable-pitch rectangular cross-section radiofrequency coils for the nitrogen-14 nuclear quadrupole resonance investigation of sealed medicines packets.  

PubMed

The performance of rectangular radio frequency (RF) coils capable of being used to detect nuclear quadrupole resonance (NQR) signals from blister packs of medicines has been compared. The performance of a fixed-pitch RF coil was compared with that from two variable-pitch coils, one based on a design in the literature and the other optimized to obtain the most homogeneous RF field over the whole volume of the coil. It has been shown from (14)N NQR measurements with two medicines, the antibiotic ampicillin (as trihydrate) and the analgesic medicine Paracetamol, that the latter design gives NQR signal intensities almost independent of the distribution of the capsules or pills within the RF coil and is therefore more suitable for quantitative analysis. PMID:23057555

Barras, Jamie; Katsura, Shota; Sato-Akaba, Hideo; Itozaki, Hideo; Kyriakidou, Georgia; Rowe, Michael D; Althoefer, Kaspar A; Smith, John A S

2012-11-01

140

Isomorphism and disorder in o-chlorohalobenzenes studied by NQR.  

PubMed

In this work we present experimental results that allow to characterize different solid modifications found in o-chlorohalobenzenes. Three disordered phases have been found in o-chlorobromobenzene. The stable phase at high temperature (phase I) is also obtained by quenching the sample at 77 K. Slow cooling allow to obtain the low temperature phase III which, on heating, transforms to phase II at 183 K and this, in turns, transforms to phase I at T~210 K. The disorder evidenced through the Nuclear Quadrupole Resonance spectra, is attributed to a random occupation of chlorine and bromine sites. In all phases there is evidence of molecular reorientations out of the benzene ring plane around the pseudo-symmetry axis between the atoms of Cl and Br. In o-chlorofluorobenzene two phases have been found depending on the cooling rate. One phase is disordered due to the random exchange of the occupation of Cl and F sites. In this case, there is also evidence of molecular reorientations out of the benzene ring plane, but in this case the reorientation is around the pseudo-symmetry axis that pass through the C-Cl bonds. Comparisons with the behavior of o-dichlorobenzene are also made. PMID:24440588

Pérez, Silvina C; Wolfenson, Alberto; Zuriaga, Mariano

2014-01-01

141

Resonant laser power build-up in ALPS—A “light shining through a wall” experiment  

NASA Astrophysics Data System (ADS)

The ALPS Collaboration runs a "light shining through a wall" (LSW) experiment to search for photon oscillations into "weakly interacting sub-eV particles" (WISPs) inside of a superconducting HERA dipole magnet at the site of DESY. In this paper we report on the first successful integration of a large-scale optical resonant cavity to boost the available power for WISP production in this type of experiments. The key elements are a frequency tunable narrow line-width continuous wave laser acting as the primary light source and an electronic feed-back control loop to stabilize the power build-up. We describe and characterize our apparatus and demonstrate the data analysis procedures on the basis of a brief exemplary run.

Ehret, Klaus; Frede, Maik; Ghazaryan, Samvel; Hildebrandt, Matthias; Knabbe, Ernst-Axel; Kracht, Dietmar; Lindner, Axel; List, Jenny; Meier, Tobias; Meyer, Niels; Notz, Dieter; Redondo, Javier; Ringwald, Andreas; Wiedemann, Günter; Willke, Benno

2009-12-01

142

Initial Experience with the Resonance Metallic Stent for Antegrade Ureteric Stenting  

SciTech Connect

Background and purpose. We describe our initial experience with a new metallic ureteric stent which has been designed to provide long-term urinary drainage in patients with malignant ureteric strictures. The aim is to achieve longer primary patency rates than conventional polyurethane ureteric stents, where encrustation and compression by malignant masses limit primary patency. The Resonance metallic double-pigtail ureteric stent (Cook, Ireland) is constructed from coiled wire spirals of a corrosion-resistant alloy designed to minimize tissue in-growth and resist encrustation, and the manufacturer recommends interval stent change at 12 months. Methods. Seventeen Resonance stents were inserted via an antegrade approach into 15 patients between December 2004 and March 2006. The causes of ureteric obstruction were malignancies of the bladder (n = 4), colon (n = 3), gynecologic (n = 5), and others (n = 3). Results. One patient had the stent changed after 12 months, and 3 patients had their stents changed at 6 months. These stents were draining adequately with minimal encrustation. Four patients are still alive with functioning stents in situ for 2-10 months. Seven patients died with functioning stents in place (follow-up periods of 1 week to 8 months). Three stents failed from the outset due to bulky pelvic malignancy resulting in high intravesical pressure, as occurs with conventional plastic stents. Conclusion. Our initial experience with the Resonance metallic ureteric stent indicates that it may provide adequate long-term urinary drainage (up to 12 months) in patients with malignant ureteric obstruction but without significantly bulky pelvic disease. This obviates the need for regular stent changes and would offer significant benefit for these patients with limited life expectancy.

Wah, Tze M., E-mail: Tze.Wah@leedsth.nhs.uk; Irving, Henry C. [St. James's University Hospital, Department of Radiology (United Kingdom); Cartledge, Jon [St. James's University Hospital, Department of Urology (United Kingdom)

2007-07-15

143

Identification of Copper(II) Complexes in Aqueous Solution by Electron Spin Resonance: An Undergraduate Coordination Chemistry Experiment.  

ERIC Educational Resources Information Center

Background, procedures, and results are provided for an experiment which examines, through electron spin resonance spectroscopy, complex species formed by cupric and 2,6-dihydroxybenzoate ions in aqueous solutions. The experiment is illustrative of several aspects of inorganic and coordination chemistry, including the identification of species…

Micera, G.; And Others

1984-01-01

144

Rabi and Larmor nuclear quadrupole double resonance of spin-1 nuclei.  

PubMed

We demonstrate the creation of two novel double-resonance conditions between spin-1 and spin-1/2 nuclei in a crystalline solid. Using a magnetic field oscillating at the spin-1/2 Larmor frequency, the nuclear quadrupole resonance (NQR) frequency is matched to the Rabi or Rabi plus Larmor frequency, as opposed to the Larmor frequency as is conventionally done. We derive expressions for the cross-polarization rate for all three conditions in terms of the relevant secular dipolar Hamiltonian, and demonstrate with these expressions how to measure the strength of the heterogenous dipolar coupling using only low magnetic fields. In addition, the combination of different resonance conditions permits the measurement of the spin-1/2 angular momentum vector using spin-1 NQR, opening up an alternate modality for the monitoring of low-field nuclear magnetic resonance. We use ammonium nitrate to explore these resonance conditions, and furthermore use the oscillating field to increase the signal-to-noise ratio per time by a factor of 3.5 for NQR detection of this substance. PMID:23231223

Prescott, D W; Malone, M W; Douglass, S P; Sauer, K L

2012-12-01

145

Rabi and Larmor nuclear quadrupole double resonance of spin-1 nuclei  

NASA Astrophysics Data System (ADS)

We demonstrate the creation of two novel double-resonance conditions between spin-1 and spin-1/2 nuclei in a crystalline solid. Using a magnetic field oscillating at the spin-1/2 Larmor frequency, the nuclear quadrupole resonance (NQR) frequency is matched to the Rabi or Rabi plus Larmor frequency, as opposed to the Larmor frequency as is conventionally done. We derive expressions for the cross-polarization rate for all three conditions in terms of the relevant secular dipolar Hamiltonian, and demonstrate with these expressions how to measure the strength of the heterogenous dipolar coupling using only low magnetic fields. In addition, the combination of different resonance conditions permits the measurement of the spin-1/2 angular momentum vector using spin-1 NQR, opening up an alternate modality for the monitoring of low-field nuclear magnetic resonance. We use ammonium nitrate to explore these resonance conditions, and furthermore use the oscillating field to increase the signal-to-noise ratio per time by a factor of 3.5 for NQR detection of this substance.

Prescott, D. W.; Malone, M. W.; Douglass, S. P.; Sauer, K. L.

2012-12-01

146

Spinning-rate encoded chemical shift correlations from rotational resonance solid-state NMR experiments  

PubMed Central

Structural measurements in magic-angle-spinning (MAS) solid-state NMR rely heavily on 13C-13C distance measurements. Broadbanded recoupling methods are used to generate many cross-peaks, but have complex polarization transfer mechanisms that limit the precision of distance constraints and can suffer from weak intensities for distant peaks due to relaxation, the broad distribution of polarization, as well as dipolar truncation. Frequency-selective methods that feature narrow-banded recoupling can reduce these effects. Indeed, rotational resonance (R2) experiments have found application in many different biological systems, where they have afforded improved precision and accuracy. Unfortunately, a highly selective transfer mechanism also leads to few cross-peaks in the resulting spectra, which complicates the extraction of multiple constraints. R2-width (R2W) measurements that scan a range of MAS rates to probe the R2 matching conditions of one or more sites can improve precision, and also permit multiple simultaneous distance measurements. Unfortunately, multidimensional R2W can be very time-consuming. Here, we present an approach that facilitates the acquisition of 2D-like spectra based on a series of 1D R2W experiments, by taking advantage of the chemical shift information encoded in the MAS rates where matching occurs. This yields a more time-efficient experiment with many of the benefits of more conventional multidimensional R2W measurements. The obtained spectra reveal long-distance 13C-13C cross-peaks resulting from R2-mediated polarization transfer. This experiment also enables the efficient setup and targeted implementation of traditional R2 or R2W experiments. Analogous applications may extend to other variable-MAS and frequency-selective solid-state NMR experiments. PMID:23475055

Li, Jun; van der Wel, Patrick C. A.

2013-01-01

147

Conformational isomerism of methyl dichloroacetate. An infrared, Raman and 35Cl NQR study  

NASA Astrophysics Data System (ADS)

The IR and Raman spectra of methyl dichloroacetate (M-DCA) have been recorded on the liquid, glassy and crystalline states. The vibrational assignment for M-DCA is proposed on the basis of the spectral comparisons between CCl nH 3? n COOCH 3 and CCl nH 5? n CONHCH 5 ( n = 0-3) in the solid state. The observed spectral data indicate that M-DCA exists as a conformational equilibrium in the liquid and in the glassy state and that the conformation in the crystalline state is entirely different from those in the liquid and glassy states. The 35Cl NQR spectrum suggests that the conformation of M-DCA in the crystalline state is the cis form in which one of the two chlorine atoms is located in the cis position with respect to the carbonyl group. Examination of vibrational spectra also leads to the same conclusion.

Mido, Yoshiyuki; Hashimoto, Masao

1985-10-01

148

Weak Magnetic Order in Bilayered-Hydrate NaxCoO2\\cdotyH2O Structure Probed by Co Nuclear Quadrupole Resonance —Proposed Phase Diagram in Superconducting NaxCoO2\\cdotyH2O---  

NASA Astrophysics Data System (ADS)

A weak magnetic order was found in a nonsuperconducting bilayered-hydrate NaxCoO2\\cdotyH2O sample by Co nuclear quadrupole resonance (NQR) measurement. The nuclear spin-lattice relaxation rate divided by temperature 1/T_1T shows a prominent peak at 5.5 K, below which a Co NQR peak splits due to an internal field at the Co site. From the analyses of the Co NQR spectrum at 1.5 K, the internal field is evaluated to be ˜300 Oe and found to be in the ab-plane. The magnitude of the internal field suggests that the ordered moment is as small as ˜0.015 ?B using the hyperfine coupling constant reported previously. It is shown that the NQR frequency ?Q correlates with magnetic fluctuations from measurements of NQR spectra and 1/T_1T in various samples. The higher-?Q sample has stronger magnetic fluctuations. A possible phase diagram for NaxCoO2\\cdotyH2O is depicted using Tc and ?Q, in which the crystal distortion along the c-axis of the tilted CoO2 octahedron is considered to be a physical parameter. Superconductivity with the highest Tc is seemingly observed in the vicinity of a magnetic phase, suggesting strongly that magnetic fluctuations play an important role in the occurrence of superconductivity.

Ihara, Yoshihiko; Ishida, Kenji; Michioka, Chishiro; Kato, Masaki; Yoshimura, Kazuyoshi; Takada, Kazunori; Sasaki, Takayoshi; Sakurai, Hiroya; Takayama-Muromachi, Eiji

2005-03-01

149

CARBON-13 Nuclear Magnetic Resonance Experiments in Powdered and Oriented Materials  

NASA Astrophysics Data System (ADS)

Sample reorientation during the mixing time of a two-dimensional ^{13}C Nuclear Magnetic Resonance (NMR) exchange experiment allows the measurement of the principal values of chemical shift tensors in powdered samples whose one-dimensional powder patterns are too complex to reliably analyze. The experiment is relatively easy to perform, and the experimental artifacts can be accounted for with a straightforward physical model. The process of fitting the powdered sample spectra produces the principal values of the chemical shift tensor, and a function that describes the experimental artifacts in the spectrum. The method is useful for sorting out the principal values of overlapping chemical shift tensor powder patterns, and it also shows promise for characterizing heterogeneous materials. The experiment is useful for characterizing order in partially oriented samples. The orientational distribution of molecular fragments in extruded and drawn polymer samples have been measured. The distribution functions are quite similar to the predictions of a normal probability distribution on a sphere. The function that describes the experimental artifacts in the powder spectrum can be used to correct the analysis of the oriented sample's spectrum, thereby increasing the accuracy of orientational distribution measurements. In certain cases, the local conformation of a macromolecule can be determined from the spectrum of a very highly oriented sample.

Hughes, Craig Dale

150

Space Time Reversal Experiment by Use of Pulsed Neutron Ramsey Resonance  

SciTech Connect

We have developed a pulsed neutron Ramsey resonance for a T-violation experiment on polarized neutron transmission through a polarized nuclear target. Two separated oscillatory fields were placed in a pulsed neutron beam line, which were synchronized with a neutron pulse for precision neutron spin manipulation. We observed neutron Larmor precession between the two oscillatory fields as a function of a neutron time of flight (TOF). We modulated the phase of the second oscillatory field with respect to the first oscillatory field. The effect of the phase modulation was found in a neutron intensity modulation as a function of the TOF. From the neutron intensity modulation, the neutron spin direction as well as the neutron velocity between the two oscillatory fields was precisely obtained.

Masuda, Y.; Jeong, S. C.; Watanabe, Y. [Institute of Particle and Nuclear Studies, KEK, Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan); Skoy, V. [Joint Institute for Nuclear Research, 14980 Dubna Moscow Region (Russian Federation); Ino, T. [Institute of Material Structure Science, KEK, Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan)

2007-06-13

151

Atomic force microscopy silicon tips as photon tunneling sensors: a resonant evanescent coupling experiment  

NASA Astrophysics Data System (ADS)

Evanescent wave conversion by transparent dielectric nanoprobes has long been achieved in photon scanning tunneling microscopy experiments. Nevertheless, the exact mechanism (i.e., resolution limit) of this optical interaction is not satisfactorily explained theoretically nor evidenced experimentally. We study the ability of doped silicon atomic force microscopy tips to capture infrared near-field waves standing at the flat surface of a semiconductor (semi-insulating InP) material. It is shown that, unlike silicon nitride tips previously studied, the transmitted intensity of these silicon tips does not obey the classical frustrated total internal reflection model but a more complex dependence that involves a resonant tunneling transfer. An explanation is proposed that follows the theoretical predictions for the electromagnetic coupling between subwavelength objects.

Fillard, J. P.; Castagne, M.; Prioleau, C.

1995-07-01

152

Effects of nonsinusoidal character of atomic modulation on NQR spin-lattice relaxation time of incommensurate phases  

SciTech Connect

The present work is an extention of the theoretical calculation developed by Blinc to explain the temperature and frequency dependence of the spin-lattice relaxation time in incommensurate phases. We have evaluated the influence of the nonsinusoidal character of the atomic modulation, in the linear approximation, over the NQR spectra and over the spin-lattice relaxation due to direct and Raman processes. It is shown that the peak with lower intensity in the NQR spectra always has a larger T{sub 1} and viceversa. The results have been applied to bis(4-chlorophenyl)sulfone T{sub 1} and line-shape data. The temperature and frequency dependence of T{sub 1} are well reproduced if Raman processes are considered.

Perez, Silvina C.; Schurrer, Clemar; Wolfenson, Alberto

2001-06-01

153

Solid-state NMR/NQR and first-principles study of two niobium halide cluster compounds.  

PubMed

Two hexanuclear niobium halide cluster compounds with a [Nb6X12](2+) (X=Cl, Br) diamagnetic cluster core, have been studied by a combination of experimental solid-state NMR/NQR techniques and PAW/GIPAW calculations. For niobium sites the NMR parameters were determined by using variable Bo field static broadband NMR measurements and additional NQR measurements. It was found that they possess large positive chemical shifts, contrary to majority of niobium compounds studied so far by solid-state NMR, but in accordance with chemical shifts of (95)Mo nuclei in structurally related compounds containing [Mo6Br8](4+) cluster cores. Experimentally determined ?iso((93)Nb) values are in the range from 2,400 to 3,000 ppm. A detailed analysis of geometrical relations between computed electric field gradient (EFG) and chemical shift (CS) tensors with respect to structural features of cluster units was carried out. These tensors on niobium sites are almost axially symmetric with parallel orientation of the largest EFG and the smallest CS principal axes (Vzz and ?33) coinciding with the molecular four-fold axis of the [Nb6X12](2+) unit. Bridging halogen sites are characterized by large asymmetry of EFG and CS tensors, the largest EFG principal axis (Vzz) is perpendicular to the X-Nb bonds, while intermediate EFG principal axis (Vyy) and the largest CS principal axis (?11) are oriented in the radial direction with respect to the center of the cluster unit. For more symmetrical bromide compound the PAW predictions for EFG parameters are in better correspondence with the NMR/NQR measurements than in the less symmetrical chlorine compound. Theoretically predicted NMR parameters of bridging halogen sites were checked by (79/81)Br NQR and (35)Cl solid-state NMR measurements. PMID:24581866

Peri?, Berislav; Gautier, Régis; Pickard, Chris J; Bosio?i?, Marko; Grbi?, Mihael S; Požek, Miroslav

2014-01-01

154

Detection of {sup 14}N and {sup 35}Cl in cocaine base and hydrochloride using NQR, NMR, and SQUID techniques  

SciTech Connect

Results from {sup 14}N pure NQR of cocaine in the free base form (cocaine base) yield a nuclear quadrupole coupling constant (NQCC) e{sup 2}Qq/h of 5.0229 ({+-}0.0001) MHz and an asymmetry parameter {eta} of 0.0395 ({+-}0.0001) at 295 K, with corresponding values of 5.0460 ({+-}0.0013) MHz and 0.0353 ({+-}0.0008) at 77 K. Both pure NQR (at 295-77 K) and a superconducting quantum interference device (SQUID) detector (at 4.2 K) were used to measure the very low (<1 MHz) {sup 14}N transition frequencies in cocaine hydrochloride; at 295 K the NQCC is 1.1780 ({+-}0.0014) MHz and the asymmetry parameter is 0.2632 ({+-}0.0034). Stepping the carrier frequency enables one to obtain a powder pattern without the severe intensity distortions that otherwise arise from finite pulse power. A powder pattern simulation using an NQCC value of 5.027 MHz and an asymmetry parameter {eta} of 0.2 agrees reasonably well with the experimental stepped-frequency spectrum. The use of pure NQR for providing nondestructive, quantitative, and highly specific detection of crystalline compounds is discussed, as are experimental strategies. 31 refs., 8 figs., 1 tab.

Yesinowski, J.P.; Buess, M.L.; Garroway, A.N. [Naval Research Lab., Washington, DC (United States); Ziegeweid, M.; Pines, A. [Univ. of California, Berkeley, CA (United States)]|[Lawrence Berkeley Lab., CA (United States)

1995-07-01

155

Nuclear Quadrupole Resonance of Cu in High-Tc Bi-Pb-Sr-Ca-Cu-O  

Microsoft Academic Search

Nuclear quadrupole resonance (NQR) signals of Cu have been discovered in the high-Tc superconducting oxide Bi-Pb-Sr-Ca-Cu-O with Tc{=}109 K. It has been observed that there are two Cu sites with a different quadrupole coupling. The temperature dependence of the nuclear relaxation rate, 1\\/T1, was similar to that of the CuO2 plane in YBa2Cu3O7. It is found that the 1\\/T1 for

Kenji Fujiwara; Yoshio Kitaoka; Kunisuke Asayama; Hiroyuki Sasakura; Sinnosuke Minamigawa; Kiyotaka Nakahigashi; Shigemitsu Nakanishi; Mineo Kogachi; Nobuo Fukuoka; Akira Yanase

1989-01-01

156

Observations of noise bands associated with the upper hybrid resonance by the Imp 6 radio astronomy experiment  

Microsoft Academic Search

The intense noise bands occurring near the upper hybrid resonanace ; frequency have been observed with the Imp 6 GSFC radio astronomy experiment in ; the plasmasphere. The identification of the upper hybrid resonance provides an ; accurate measure of the local electron density and allows the observed noise data ; to be fit to the scale of characteristic frequencies

Stephen R. Mosier; Michael L. Kaiser; L. W. Brown

1973-01-01

157

Two dimensional 31P nuclear magnetic resonance coherence transfer experiments under magic-angle sample spinning  

NASA Astrophysics Data System (ADS)

In this paper, we report on two dimensional (2D) 31P cross polarization (CP) magic angle spinning (MAS) nuclear magnetic resonance (NMR) experiments on the coupled two-spin systems, sodium pyrophosphate decahydrate, Na4P2O7, 1OH2O (SP) and tetraphenyldiphosphine-1-oxide, (C6H5)2PP(O) (C6H5)2 (TPPO), including antiecho (COSY), double-quantum NMR, and zero-quantum NMR experiments. These experiments are generalizations of the absolute mode 2D Fourier transform antiecho COSY performed under MAS condition by Kentgens, de Boer, and Veeman [J. Chem. Phys. 87, 6859 (1987)]. The 2D sideband intensities for these experiments on polycrystalline samples are shown theoretically to be real. There are two mechanisms of coherence transfer; homonuclear J coupling and dipolar coupling. Theory shows that the zero-quantum signal for the coupled two spins can not be observed by using a (CPx-?-(?)x-?-(?/2)x-t1-(?/2)-t2 pulse sequence, when the coherence transfer is due to J coupling. When, however, the coherence transfer is induced by the flip-flop term of the dipolar coupling Hamiltonian, the zero-quantum signal can be observed by that pulse sequence. The preparation time dependences of the double-quantum and the zero-quantum sideband patterns, are expected, when the coherence transfer is induced by dipolar coupling. The zero-quantum signal was very weak for TPPO, while it was strong for SP. The apparent preparation time dependence of the zero-quantum sideband pattern was observed for SP. These results suggest that the coherence transfer is mainly due to J coupling in TPPO, where the two 31P nuclei have different isotropic chemical shifts. While, on the other hand, the dipolar coupling is more important in SP, where the two 31P nuclei have the same isotropic chemical shifts but different orientations of the chemical shift tensors. The 2D sideband intensities of the antiecho COSY spectrum of TPPO were calculated, and the relative orientation of the two chemical shift tensors was determined.

Kubo, Atsushi; Root, Andrew; McDowell, Charles A.

1990-10-01

158

Electron cyclotron resonance ion source experience at the Heidelberg Ion Beam Therapy Center  

SciTech Connect

Radiotherapy with heavy ions is an upcoming cancer treatment method with to date unparalleled precision. It associates higher control rates particularly for radiation resistant tumor species with reduced adverse effects compared to conventional photon therapy. The accelerator beam lines and structures of the Heidelberg Ion Beam Therapy Center (HIT) have been designed under the leadership of GSI, Darmstadt with contributions of the IAP Frankfurt. Currently, the accelerator is under commissioning, while the injector linac has been completed. When the patient treatment begins in 2008, HIT will be the first medical heavy ion accelerator in Europe. This presentation will provide an overview about the project, with special attention given to the 14.5 GHz electron cyclotron resonance (ECR) ion sources in operation with carbon, hydrogen, helium, and oxygen, and the experience of one year of continuous operation. It also displays examples for beam emittances, measured in the low energy beam transport. In addition to the outlook of further developments at the ECR ion sources for a continuously stable operation, this paper focuses on some of the technical processings of the past year.

Winkelmann, T.; Cee, R.; Haberer, T.; Naas, B.; Peters, A.; Scheloske, S.; Spaedtke, P.; Tinschert, K. [Heidelberger Ionenstrahl-Therapie Centrum (HIT), D-69120 Heidelberg (Germany); GSI Darmstadt, D-64291 Darmstadt (Germany)

2008-02-15

159

Magnetic Resonance Imaging in Multiple Sclerosis – Patients' Experiences, Information Interests and Responses to an Education Programme  

PubMed Central

Background Magnetic resonance imaging (MRI) is a key diagnostic and monitoring tool in multiple sclerosis (MS) management. However, many scientific uncertainties, especially concerning correlates to impairment and prognosis remain. Little is known about MS patients' experiences, knowledge, attitudes, and unmet information needs concerning MRI. Methods We performed qualitative interviews (n?=?5) and a survey (n?=?104) with MS patients regarding MRI patient information, and basic MRI knowledge. Based on these findings an interactive training program of 2 hours was developed and piloted in n?=?26 patients. Results Interview analyses showed that patients often feel lost in the MRI scanner and left alone with MRI results and images while 90% of patients in the survey expressed a high interest in MRI education. Knowledge on MRI issues was fair with some important knowledge gaps. Major information interests were relevance of lesions as well as the prognostic and diagnostic value of MRI results. The education program was highly appreciated and resulted in a substantial knowledge increase. Patients reported that, based on the program, they felt more competent to engage in encounters with their physicians. Conclusion This work strongly supports the further development of an evidence-based MRI education program for MS patients to enhance participation in health-care. PMID:25415501

Brand, Judith; Köpke, Sascha; Kasper, Jürgen; Rahn, Anne; Backhus, Imke; Poettgen, Jana; Stellmann, Jan-Patrick; Siemonsen, Susanne; Heesen, Christoph

2014-01-01

160

Experiments with biased side electrodes in electron cyclotron resonance ion sources.  

PubMed

The output of highly charged ions from an electron cyclotron resonance ion source (ECRIS) consists of ionic losses from a highly confined plasma. Therefore, an increase of the output of the ions of interest always is a compromise between an increase in the confinement and an increase of the losses. One route towards a solution consists of attacking the losses in directions - i.e., radial directions - that do not contribute to the required output. This was demonstrated in an experiment (using the Kei ECRIS at NIRS, Japan) where radial losses were electrostatically reduced by positively biasing one set of six "side" electrodes surrounding the plasma in side-ward directions attached (insulated) to the cylindrical wall of the plasma chamber. Recently new studies were performed in two laboratories using two essentially different ion sources. At the BioNano ECRIS (Toyo University, Japan) various sets of electrodes were used; each of the electrodes could be biased individually. At the Atomki ECRIS (Hungary), one movable, off-axis side electrode was applied in technically two versions. The measurements show indeed a decrease of ionic losses but different effectivities as compared to the biased disk. PMID:24593500

Drentje, A G; Kitagawa, A; Uchida, T; Rácz, R; Biri, S

2014-02-01

161

The 14N NQR spectrum and the crystal structure of Ba[Fe(CN) 5NO] · 3H 2O at room temperature  

NASA Astrophysics Data System (ADS)

The previously reported 14N NQR spectrum of the CN groups of Ba [Fe (CN) 5NO] · 3H 2O (BNP) was shown to also contain lines of Na 2 [Fe (CN) 5NO] · 2H 2O used in the preparation of BNP. The number of NQR lines and their relative intensities in BNP confirmed that it has a Pbcm instead of a Pca2 1 space group at 293 K as previously assumed. The three CN sites found in BNP at room temperature are increased to five below 233 K and to eight below 131 K as a result of phase transitions. The effect on the NQR lines of the axial CN group of the disorder of some water molecules in BNP is also discussed.

Murgich, Juan; Bonalde, Ismardo

1990-07-01

162

Detection of ¹⁴N and ³⁵Cl in cocaine base and hydrochloride using NQR, NMR, and SQUID techniques  

Microsoft Academic Search

Results from ¹⁴N pure NQR of cocaine in the free base form (cocaine base) yield a nuclear quadrupole coupling constant (NQCC) e²Qq\\/h of 5.0229 ({+-}0.0001) MHz and an asymmetry parameter η of 0.0395 ({+-}0.0001) at 295 K, with corresponding values of 5.0460 ({+-}0.0013) MHz and 0.0353 ({+-}0.0008) at 77 K. Both pure NQR (at 295-77 K) and a superconducting quantum

James P. Yesinowski; Michael L. Buess; Allen N. Garroway; Marcia. Ziegeweid; Alexander. Pines

1995-01-01

163

Frequency Response of an Air Resonance Tube--Some Computer-Interfaced Experiments.  

ERIC Educational Resources Information Center

Describes a measurement system for recording the frequency response of acoustic systems. The computer interface detects the characteristic modes, their relative strengths, and resonant shapes over a broad range of frequencies. Includes experimental data for tubes and analyzes the data to determine the optimal functional form for the resonant…

Jolly, Pratibha; And Others

1993-01-01

164

Injection Seeding of Ti:Al2O3 in an unstable resonator theory and experiment  

NASA Technical Reports Server (NTRS)

Injection Seeding of a Ti:Al2O3 unstable resonator using both a pulsed single-mode Ti:Al2O3 laser and a continuous wave laser diode has been characterized. Results are compared with a theory which calculates injection seeding as function of seed and resonator alignment, beam profiles, and power.

Barnes, J. C.; Wang, L. G.; Barnes, N. P.; Edwards, W. C.; Cheng, W. A.; Hess, R. V.; Lockard, G. E.; Ponsardin, P. L.

1991-01-01

165

Measurement of the 14N nuclear quadrupole resonance frequencies by the solid effect  

NASA Astrophysics Data System (ADS)

1H- 14N nuclear quadrupole double resonance using magnetic field cycling between high and low magnetic field and solid effect in the low magnetic field is analyzed in details. The transition probabilities per unit time for the solid-effect transitions are calculated. The double resonance spectra are calculated in the limiting cases of fast and slow nitrogen spin-lattice relaxation. The double resonance spectra are measured in histamine and quinolinic acid. The experimental spectra are analyzed and the 14N NQR frequencies are determined.

Seliger, J.; Žagar, V.

2008-07-01

166

Results from the TARC experiment: spallation neutron phenomenology in lead and neutron-driven nuclear transmutation by adiabatic resonance crossing  

Microsoft Academic Search

We summarize here the results of the TARC experiment whose main purpose is to demonstrate the possibility of using Adiabatic Resonance Crossing (ARC) to destroy efficiently Long-Lived Fission Fragments (LLFFs) in accelerator-driven systems and to validate a new simulation developed in the framework of the Energy Amplifier programme. An experimental set-up was installed in a CERN PS proton beam line

A. Abánades; J. Aleixandre; Samuel A Andriamonje; Angelos Angelopoulos; Alcibiades J Apostolakis; H. Arnould; E. Belle; C. A Bompas; Delecurgo Brozzi; J. Bueno; S. Buono; F. Carminati; Federico Casagrande; P. Cennini; J. I. Collar; E. Cerro; R. Del Moral; S D??ez; C Eleftheriadis; M Embid; R Fernández; J Gálvez; J Garc??a; C Gelès; A Giorni; E González; O González; I Goulas; D Heuer; M Hussonnois; Y Kadi; P Karaiskos; G Kitis; R Klapisch; P Kokkas; V Lacoste; C. Le Naour; Cayetano Lopez Martinez; J. M Loiseaux; J. M Mart??nez-Val; O Méplan; H Nifenecker; J Oropesa; I M Papadopoulos; P Pavlopoulos; E Pérez-Enciso; A Pérez-Navarro; M Perlado; A Placci; M Poza; Jean Pierre Charles Revol; Carlo Rubbia; Juan Antonio Rubio; L Sakelliou; F Saldaña; E Savvidis; F Schussler; C Sirvent; J Tamarit; D Trubert; A Tzima; J. B Viano; S L Vieira; V Vlachoudis; Konstantin Zioutas

2002-01-01

167

Analysis of nuclear-quadrupole-resonance spectrum of incommensurate phases: The case of bis(4-chlorophenyl) sulfone  

Microsoft Academic Search

In this work, previous experimental studies of the 35Cl nuclear-quadrupole-resonance (NQR) line shape in the incommensurate phase of bis(4-chlorophenyl) sulfone were extended. The broad spectra in the incommensurate phase (IC) were measured using the Fourier transform of the nuclear signal to avoid systematic errors committed in some studies of this compound. The results were interpreted within the framework of the

J. Schneider; C. Schürrer; A. Wolfenson; A. Brunetti

1998-01-01

168

A study of the semiconductor compound ?uAlO2 by the method of nuclear quadrupole resonance of Cu  

NASA Astrophysics Data System (ADS)

The method of nuclear quadrupole resonance of Cu (NQR Cu) is used to study the samples of a semiconductor compound CuAlO2. The crystal structure of CuAlO2 belongs to the family of delafossite - the mineral of a basic CuFeO2 structure. Transparent semiconductor oxides, such as CuAlO2, have attracted recent attention as promising thermoelectric materials.

Matukhin, V. L.; Khabibulin, I. Kh.; Shul'gin, D. A.; Smidt, S. V.

2012-07-01

169

An ultrahigh-vacuum apparatus for resonant diffraction experiments using soft x rays (hnu=300-2000 eV).  

PubMed

We have developed an ultrahigh-vacuum instrument for resonant diffraction experiments using polarized soft x rays in the energy range of hnu=300-2000 eV at beamline BL17SU of SPring-8. The diffractometer consists of modified differentially pumped rotary feedthroughs for theta-2theta stages, a sample manipulator with motor-controlled x-y-z-, tilt (chi)-, and azimuth (phi)-axes, and a liquid helium flow-type cryostat for temperature dependent measurements between 30 and 300 K. Test results indicate that the diffractometer exhibits high reproducibility (better than 0.001 degrees ) for a Bragg reflection of alpha-quartz 100 at a photon energy of hnu=1950 eV. Typical off- and on-resonance Bragg reflections in the energy range of 530-1950 eV could be measured using the apparatus. The results show that x-ray diffraction experiments with energy-, azimuth-, and incident photon polarization-dependence can be reliably measured using soft x rays in the energy range of approximately 300-2000 eV. The facility can be used for resonant diffraction experiments across the L-edge of transition metals, M-edge of lanthanides, and up to the Si K-edge of materials. PMID:19256660

Takeuchi, T; Chainani, A; Takata, Y; Tanaka, Y; Oura, M; Tsubota, M; Senba, Y; Ohashi, H; Mochiku, T; Hirata, K; Shin, S

2009-02-01

170

Cavity-Enhanced IR Absorption in Planar Chalcogenide Glass Microdisk Resonators: Experiment and Analysis  

E-print Network

Planar microdisk optical resonators fabricated from Ge[subscript 23]Sb[subscript 7]S[subscript 70] chalcogenide glass on a silicon substrate are applied for cavity-enhanced spectroscopic measurement of chemical molecular ...

Kimerling, Lionel C.

171

Toward Resonant, Imaginative Experiences in Ecological and Democratic Education. A Response to "Imagination and Experience: An Integrative Framework"  

ERIC Educational Resources Information Center

In this response to Fettes's "Imagination and Experience," the authors further consider the varieties of educational experience that inspire ecological flourishing and a living democracy. The essential interconnectedness of encounter-driven and language-driven ways of knowing are explored with particular reference to the…

Derby, Michael; Blenkinsop, Sean; Telford, John; Piersol, Laura; Caulkins, Michael

2013-01-01

172

I: Low Frequency NMR and NQR Using a dc SQUID. II: Variable-temperature 13C CP\\/MAS of Organometallics  

Microsoft Academic Search

NMR and NQR at low frequencies are difficult prospects due to small nuclear spin polarization. Furthermore, the sensitivity'of the inductive pickup circuitry of standard spectrometers is reduced as the frequency is lowered. I have used a cw-SQUID (Superconducting QUantum Interference Device) spectrometer, which has no such frequency dependence, to study the local atomic environment of ¹N via the quadrupolar interaction.

Ziegeweid

1995-01-01

173

Central role of the Na+-translocating NADH:quinone oxidoreductase (Na+-NQR) in sodium bioenergetics of Vibrio cholerae.  

PubMed

Abstract Vibrio cholerae is a Gram-negative bacterium that lives in brackish or sea water environments. Strains of V. cholerae carrying the pathogenicity islands infect the human gut and cause the fatal disease cholera. Vibrio cholerae maintains a Na+ gradient at its cytoplasmic membrane that drives substrate uptake, motility, and efflux of antibiotics. Here, we summarize the major Na+-dependent transport processes and describe the central role of the Na+-translocating NADH:quinone oxidoreductase (Na+-NQR), a primary Na+ pump, in maintaining a Na+-motive force. The Na+-NQR is a membrane protein complex with a mass of about 220 kDa that couples the exergonic oxidation of NADH to the transport of Na+ across the cytoplasmic membrane. We describe the molecular architecture of this respiratory complex and summarize the findings how electron transport might be coupled to Na+-translocation. Moreover, recent advances in the determination of the three-dimensional structure of this complex are reported. PMID:25205724

Steuber, Julia; Halang, Petra; Vorburger, Thomas; Steffen, Wojtek; Vohl, Georg; Fritz, Günter

2014-12-01

174

A 4 K cryogenic probe for use in magnetic resonance force microscopy experiments  

NASA Astrophysics Data System (ADS)

The detailed design of a mechanically detected nuclear magnetic resonance probe using the SPAM (Springiness Preservation by Aligning Magnetization) geometry, operating at 4 K, in vacuum, and a several-Tesla magnetic field is described. The probe head is vibration-isolated well enough from the environment by a three-spring suspension system that the cantilever achieves thermal equilibrium with the environment without the aid of eddy current damping. The probe uses an ultra-soft Si cantilever with a Ni sphere attached to its tip, and magnetic resonance is registered as a change in the resonant frequency of the driven cantilever. The RF system uses frequency sweeps for adiabatic rapid passage using a 500 ?m diameter RF coil wound around a sapphire rod. The RF coil and optical fiber of the interferometer used to sense the cantilever's position are both located with respect to the cantilever using a Garbini micropositioner, and the sample stage is mounted on an Attocube nanopositioner.

Smith, Doran D.; Alexson, Dimitri A.; Garbini, Joseph L.

2013-09-01

175

Theory and experiment on resonant frequencies of liquid-air interfaces trapped in microfluidic devices  

PubMed Central

Bubble-based microfluidic devices have been proven to be useful for many biological and chemical studies. These bubble-based microdevices are particularly useful when operated at the trapped bubbles' resonance frequencies. In this work, we present an analytical expression that can be used to predict the resonant frequency of a bubble trapped over an arbitrary shape. Also, the effect of viscosity on the dispersion characteristics of trapped bubbles is determined. A good agreement between experimental data and theoretical results is observed for resonant frequency of bubbles trapped over different-sized rectangular-shaped structures, indicating that our expression can be valuable in determining optimized operational parameters for many bubble-based microfluidic devices. Furthermore, we provide a close estimate for the harmonics and a method to determine the dispersion characteristics of a bubble trapped over circular shapes. Finally, we present a new method to predict fluid properties in microfluidic devices and complement the explanation of acoustic microstreaming. PMID:24343156

Chindam, Chandraprakash; Nama, Nitesh; Ian Lapsley, Michael; Costanzo, Francesco; Jun Huang, Tony

2013-01-01

176

A 4 K cryogenic probe for use in magnetic resonance force microscopy experiments  

SciTech Connect

The detailed design of a mechanically detected nuclear magnetic resonance probe using the SPAM (Springiness Preservation by Aligning Magnetization) geometry, operating at 4 K, in vacuum, and a several-Tesla magnetic field is described. The probe head is vibration-isolated well enough from the environment by a three-spring suspension system that the cantilever achieves thermal equilibrium with the environment without the aid of eddy current damping. The probe uses an ultra-soft Si cantilever with a Ni sphere attached to its tip, and magnetic resonance is registered as a change in the resonant frequency of the driven cantilever. The RF system uses frequency sweeps for adiabatic rapid passage using a 500 ?m diameter RF coil wound around a sapphire rod. The RF coil and optical fiber of the interferometer used to sense the cantilever's position are both located with respect to the cantilever using a Garbini micropositioner, and the sample stage is mounted on an Attocube nanopositioner.

Smith, Doran D.; Alexson, Dimitri A. [U.S. Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland 20783 (United States)] [U.S. Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland 20783 (United States); Garbini, Joseph L. [Mechanical Engineering, University of Washington, Seattle, Washington 98195 (United States)] [Mechanical Engineering, University of Washington, Seattle, Washington 98195 (United States)

2013-09-15

177

Nuclear quadrupole resonance studies of the SORC sequence and nuclear magnetic resonance studies of polymers  

SciTech Connect

The behavior of induction signals during steady-state pulse irradiation in {sup 14}N NQR was investigated experimentally. Because Strong Off-resonance Comb (SORC) signals recur as long as the pulsing continues, very efficient signal-averaging can result. The dependence of these steady-state SORC signals on pulse parameters and on frequency offset are presented, together with a discussion of the applicability of the method. Also as part of the NQR work, cocaine base has been detected using conventional NQR techniques. The experimental results show that SORC detection can be of sufficient sensitivity to form the basis of narcotics screening devices for both mail and airline baggage. A new NMR technique, to obtain the correlation time of the random thermal motion of a polymer at temperatures near the glass transition has been introduced. The temperature dependence is a result of thermal motion. For slow-motion of a polymer chain near the glass transition, the CSA parameter begins to decrease. This motional narrowing can be interpreted to yield the correlation time of the thermal motion. In this work nitrocellulose isotopically highly enriched with {sup 15}N was studied at four different temperatures between 27{degrees} and 120{degrees} Celsius and the correlation times for polymer backbone motions were obtained. Naflon films containing water (D{sub 2}O and H{sub 2} {sup 17}O) and methanol (CH{sub 3}OD, CH{sub 3} {sup 17}OH), have been studied using deuteron and oxygen-17 NMR spectroscopy. Glassy behavior of the water domains at low temperature is evidenced by the specific nature of the {sup 2}H NMR lineshapes. Activation energies extracted from {sup 2}H spin-lattice relaxation data on the high temperature side of the T{sub 1} minimum exhibit a steady increase with increasing water content. In spite of a high degree of molecular mobility, angular-dependent spectra of both unstretched and stretched samples reflect considerable anisotrophy of the host polymer.

Jayakody, J.R.P.

1993-12-31

178

An Accessible Two-Dimensional Solution Nuclear Magnetic Resonance Experiment on Human Ubiquitin  

ERIC Educational Resources Information Center

Solution-state nuclear magnetic resonance (NMR) is an invaluable tool in structural and molecular biology research, but may be underutilized in undergraduate laboratories because instrumentation for performing structural studies of macromolecules in aqueous solutions is not yet widely available for use in undergraduate laboratories. We have…

Rovnyak, David; Thompson, Laura E.

2005-01-01

179

Pulse Transmission across a Single Optical Ring-Resonator with Negative Group Velocity: Theory and Experiment  

Microsoft Academic Search

We study pulse transmission across a single optical ring-resonator circuit theoretically. The theory is supported by experimental measurements. From the study, we discuss intuitively the fulfillment of the causality rules in negative delay phenomenon, which occurs when the circuit possesses a negative group velocity.

H. P. Uranus; L. Zhuang; C. G. H. Roeloffzen; H. J. W. M. Hoekstra

2008-01-01

180

Magnetic Criticality and Unconventional Superconductivity in CeCoIn5: Study of 115In-Nuclear Quadrupole Resonance under Pressure  

Microsoft Academic Search

We report the systematic evolution of the superconducting (SC) characteristics of the heavy-fermion (HF) superconductor CeCoIn5 via nuclear-quadrupole-resonance (NQR) measurement under pressure (P). The application of P significantly suppresses the nuclear spin-lattice relaxation rate 1\\/T1 that is dominated by antiferromagnetic (AFM) spin fluctuations (SFs) specific to a quantum critical point (QCP). It is demonstrated that the marked suppression of AFM

M. Yashima; S. Kawasaki; Y. Kawasaki; G.-q. Zheng; Y. Kitaoka; H. Shishido; R. Settai; Y. Haga; Y. Onuki

2004-01-01

181

Nucleon Resonances Spin Structure - RSS: Experiment 01-006 at Jefferson Lab  

SciTech Connect

We have measured the spin structure of the nucleon in the region of the resonances (final state mass W <~ 2 GeV) at intermediate four-momentum transfer Q^2 ~ 1.3 (GeV/c)^2. Double-spin inclusive asymmetries for longitudinally polarized 5.75 GeV electrons incident on longitudinal and transverse solid polarized targets were measured in Jefferson Lab's Hall C. Frozen ammonia and deuterated ammonia were used as the polarized materials. The neutron spin structure is extracted from the proton and deuteron asymmetries. We present new results for the proton measured asymmetries A|| and A[perpendicular] and spin structure functions g_1 and g_2, and preliminary results for the deuteron asymmetries. These are the first measurements of the transverse proton and deuteron spin structure in the resonances. We also report on our measurement of the ratio of the proton electromagnetic form factors with our polarized target.

Rondon-Aramayo, Oscar

2006-07-01

182

Nucleon Resonances Spin Structure - RSS: Experiment 01-006 at Jefferson Lab  

SciTech Connect

We have measured the spin structure of the nucleon in the region of the resonances (final state mass W <{approx} 2 GeV) at intermediate four-momentum transfer Q2 {approx} 1.3 (GeV/c)2. Double-spin inclusive asymmetries for longitudinally polarized 5.75 GeV electrons incident on longitudinal and transverse solid polarized targets were measured in Jefferson Lab's Hall C. Frozen ammonia and deuterated ammonia were used as the polarized materials. The neutron spin structure is extracted from the proton and deuteron asymmetries. We present new results for the proton measured asymmetries A parallel and A perpendicular and spin structure functions g1 and g2, and preliminary results for the deuteron asymmetries. These are the first measurements of the transverse proton and deuteron spin structure in the resonances. We also report on our measurement of the ratio of the proton electromagnetic form factors with our polarized target.

Rondon, Oscar A. [University of Virginia, Charlottesville, VA 22901 (United States)

2006-07-11

183

Theory and experiment of circularly polarized dielectric resonator antenna with a parasitic patch  

Microsoft Academic Search

The use of a single parasitic patch for circular polarization (CP) excitation of the dielectric resonator antenna (DRA) is investigated. For demonstration, the technique is applied to the conformal-strip fed hemispherical DRA, excited at the fundamental TE111 mode. Using the Green's function approach, the integral equations for the conformal-strip and parasitic-patch currents are formulated by matching the appropriate boundary conditions.

Kwok Wa Leung; Hoi Kuen Ng

2003-01-01

184

Coaxial probe for nuclear magnetic resonance diffusion and relaxation correlation experiments  

NASA Astrophysics Data System (ADS)

A coaxial nuclear magnetic resonance (NMR) probe is built to measure diffusion and relaxation properties of liquid samples. In particular, we demonstrate the acquisition of two-dimensional (2D) distribution functions (T1-T2 and diffusion-T2), essential for fluids characterization. The compact design holds promise for miniaturization, thus enabling the measurement of molecular diffusion that is inaccessible to conventional micro-NMR setups. Potential applications range from crude oil characterization to biomolecular screening and detections.

Tang, Yiqiao; Hürlimann, Martin; Mandal, Soumyajit; Paulsen, Jeffrey; Song, Yi-Qiao

2014-02-01

185

Continuous-wave, two-crystal, singly-resonant optical parametric oscillator: theory and experiment.  

PubMed

We present theoretical and experimental study of a continuous-wave, two-crystal, singly-resonant optical parametric oscillator (T-SRO) comprising two identical 30-mm-long crystals of MgO:sPPLT in a four- mirror ring cavity and pumped with two separate pump beams in the green. The idler beam after each crystal is completely out-coupled, while the signal radiation is resonant inside the cavity. Solving the coupled amplitude equations under undepleted pump approximation, we calculate the maximum threshold reduction, parametric gain acceptance bandwidth and closest possible attainable wavelength separation in arbitrary dual-wavelength generation and compare with the experimental results. Although the T-SRO has two identical crystals, the acceptance bandwidth of the device is equal to that of a single-crystal SRO. Due to the division of pump power in two crystals, the T-SRO can handle higher total pump power while lowering crystal damage risk and thermal effects. We also experimentally verify the high power performance of such scheme, providing a total output power of 6.5 W for 16.2 W of green power at 532 nm. We verified coherent energy coupling between the intra-cavity resonant signal waves resulting Raman spectral lines. Based on the T-SRO scheme, we also report a new technique to measure the temperature acceptance bandwidth of the single-pass parametric amplifier across the OPO tuning range. PMID:23609663

Samanta, G K; Aadhi, A; Ebrahim-Zadeh, M

2013-04-22

186

Microscopic properties of the heavy-fermion superconductor PuCoIn5 explored by nuclear quadrupole resonance  

NASA Astrophysics Data System (ADS)

We report 115In nuclear quadrupolar resonance (NQR) measurements on the heavy-fermion superconductor PuCoIn5, in the temperature range 0.29K ? T ? 75K. The NQR parameters for the two crystallographically inequivalent In sites are determined, and their temperature dependence is investigated. A linear shift of the quadrupolar frequency with lowering temperature below the critical value Tc is revealed, in agreement with the prediction for composite pairing. The nuclear spin-lattice relaxation rate T1-1(T) clearly signals a superconducting (SC) phase transition at Tc ? 2.3 K, with strong spin fluctuations, mostly in-plane, dominating the relaxation process in the normal state near to Tc. Analysis of the T1-1 data in the SC state suggests that PuCoIn5 is a strong-coupling d-wave superconductor.

Koutroulakis, G.; Yasuoka, H.; Chudo, H.; Tobash, P. H.; Mitchell, J. N.; Bauer, E. D.; Thompson, J. D.

2014-05-01

187

Low-power stimulated emission nuclear quadrupole resonance detection system utilizing Rabi transitions  

NASA Astrophysics Data System (ADS)

The application of CW radar techniques to Nuclear Quadrupole Resonance (NQR) detection of nitrogen based explosives and chlorine based narcotics enables the use of low power levels, in the range of 10's of watts, to yield high signal strengths. By utilizing Rabi transitions the nucleus oscillates between states one and two under the time dependent incident electromagnetic field and alternately absorbs energy from the incident field while emitting coherent energy via stimulated emission. Through the application of a cancellation algorithm the incident field is eliminated from the NQR response, allowing the receive signal to be measured while transmitting. The response signal is processed using matched filters of the NQR response which enables the direct detection of explosives. This technology has applicability to the direct detection of explosives and narcotics for security screening, all at safe low power levels, opposed to the current XRay and Millimeter wave screening systems that detect objects that may contain explosives and utilize high power. The quantum mechanics theoretical basis for the approach and an application for a system for security screening are described with empirical results presented to show the effects observed.

Apostolos, John; Mouyos, William; Feng, Judy; Chase, Walter

2013-06-01

188

Using an NMR Spectrometer to Do Magnetic Resonance Imaging: An Undergraduate Physical Chemistry Laboratory Experiment  

ERIC Educational Resources Information Center

A conventional Fourier-transform NMR spectrometer with a triple-axis gradient probe can function as a MRI imager. In this experiment students gain hands-on experience with MRI while they learn about important principles underlying the practice of NMR, such as gradients, multi-dimensional spectroscopy, and relaxation. Students image a biological…

Steinmetz, Wayne E.; Maher, M. Cyrus

2007-01-01

189

Coaxial probe for nuclear magnetic resonance diffusion and relaxation correlation experiments  

SciTech Connect

A coaxial nuclear magnetic resonance (NMR) probe is built to measure diffusion and relaxation properties of liquid samples. In particular, we demonstrate the acquisition of two-dimensional (2D) distribution functions (T{sub 1}-T{sub 2} and diffusion–T{sub 2}), essential for fluids characterization. The compact design holds promise for miniaturization, thus enabling the measurement of molecular diffusion that is inaccessible to conventional micro-NMR setups. Potential applications range from crude oil characterization to biomolecular screening and detections.

Tang, Yiqiao; Hürlimann, Martin; Mandal, Soumyajit; Paulsen, Jeffrey; Song, Yi-Qiao, E-mail: ysong@slb.com [Schlumberger-Doll Research, 1 Hampshire Street, Cambridge, Massachusetts 02139 (United States)

2014-02-21

190

Estimation of parasitic losses in a proposed mesoscale resonant engine: Experiment and model  

NASA Astrophysics Data System (ADS)

A resonant engine in which the piston-cylinder assembly is replaced by a flexible cavity is realized at the mesoscale using flexible metal bellows to demonstrate the feasibility of the concept. A four stroke motoring technique is developed and measurements are performed to determine parasitic losses. A non-linear lumped parameter model is developed to evaluate the engine performance. Experimentally, the heat transfer and friction effects are separated by varying the engine speed and operating frequency. The engine energy flow diagram showing the energy distribution among various parasitic elements reveals that the friction loss in the bellows is smaller than the sliding friction loss in a typical piston-cylinder assembly.

Preetham, B. S.; Anderson, M.; Richards, C.

2014-02-01

191

Power instability of singly resonant optical parametric oscillators: theory and experiment.  

PubMed

We present a theoretical model on the effects of mechanical perturbations on the output power instability of singly-resonant optical parametric oscillators (SR-OPOs). Numerical simulations are performed based on real experimental parameters associated with a SR-OPO designed in our laboratory, which uses periodically-poled LiNbO3 (PPLN) as the nonlinear crystal, where the results of the theoretical model are compared with the measurements. The out-coupled power instability is simulated for a wide range of input pump powers the SR-OPO oscillation threshold. From the results, maximum instability is found to occur at an input pump power of ~1.5 times above the OPO threshold. It is also shown theoretically that the idler instability is susceptible to variations in the cavity length caused by vibrations, with longer cavities capable of generating more stable output power. The validity of the theoretical model is verified experimentally by using a mechanical vibrator in order to vary the SR-OPO resonator length over one cavity mode spacing. It is found that at 1.62 times threshold, the out-coupled idler suffers maximum instability. The results of experimental measurements confirm good agreement with the theoretical model. An intracavity etalon is finally used to improve the idler output power by a factor of ~2.2 at an input pump power of 1.79 times oscillation threshold. PMID:23262694

Sabouri, Saeed Ghavami; Khorsandi, Alireza; Ebrahim-Zadeh, Majid

2012-12-01

192

Structure and Nuclear Magnetic Resonance. An Experiment for the General Chemistry Laboratory  

NASA Astrophysics Data System (ADS)

We have developed an experiment that introduces freshman chemistry students to NMR. Students are trained to work on the instrument, analyze 1H and 13C spectra, and identify simple organic molecules. They are also introduced to the idea of functional groups and they use concepts learned in class about Lewis structures to distinguish among spectra of isomers of C3H8O. As part of this exercise students submit written reports and complete a survey evaluating the experiment. The lab experiment, survey results, and findings are presented.

Dávila, Rosa M.; Widener, R. K.

2002-08-01

193

[Heart involvement in thymic neoformations: the role of magnetic resonance tomography. Experience in 3 cases].  

PubMed

Three paracardiac masses (1 thymic cyst, 2 thymomas) were studied by magnetic resonance imaging (MRI) using spin-echo, multi-echo, and gradient-echo sequences (cine-MR). MRI showed: a pedunculate cystic lesion, typical for thymic origin, in Case 1; cardiac and pulmonary infiltration, and 3 intracardiac metastases, in Case 2; cardiovascular compression but not infiltration, in Case 3. In 3/3 cases MRI was superior to transthoracic echocardiography (TTE), and in 2/2 MRI was superior to computed tomography (CT), not performed in Case 2 (allergy to contrast agents). MRI may be considered the most important technique to evaluate cardiovascular involvement by thymic neoplasms. MRI should be performed after TTE and makes CT unnecessary. PMID:8200016

Molinari, G; Sardanelli, F; Ottonello, C; Maragliano, P; Passerone, G; Costa, S; Caponnetto, S

1993-12-01

194

Basic experiments on in-situ magnetized boronization by electron cyclotron resonance discharges  

NASA Astrophysics Data System (ADS)

Boronization based on electron cyclotron resonance (ECR) discharges is studied in a linear laboratory device under a parallel magnetic field of ˜ 0.1 T. A 2.45 GHz ECR discharge in a low-pressure {helium}/{decaborane} mixture gives thin boron films localized on the walls near the gas inlet. In order to understand such film distributions, artificial deposition on plasma-exposed substrates in carried out. Two types of deposition processes are successfully discriminated in the magnetized plasma. One is neutral-induced deposition near the gas inlet and the other is ion-induced deposition in a downstream region. The latter plays a significant role in high-field high-density discharges. A simple scaling of deposition profile for each type of deposition is given along with its implication for achieving a deposition uniformity.

Kokura, H.; Sasaki, K.; Toyoda, H.; Mizuuchi, T.; Kondo, K.; Sano, F.; Obiki, T.; Sugai, H.

1997-02-01

195

Hydrogen transfer in hydrogen-bonded chloranilic acid studied by 35Cl NQR I - a 1:2 complex with 1,4-diazine  

NASA Astrophysics Data System (ADS)

35Cl NQR frequencies and spin-lattice relaxation time ( T1Q) and 1H NMR relaxation times ( T1H) in a H-bonded three molecular system, chloranilic acid-1,4-diazine (1:2) were measured to reveal H-motions in a symmetric two H-bonds in solid. A single 35Cl NQR frequency observed implies that the time-averaged structure of chloranilic acid is roughly monovalent in accordance with p Ka values in both acid and base. T1H temperature dependence was explained by a single relaxation mechanism due to the correlated H-transfer in two H-bonds, while that of T1Q yielded two relaxation processes. One of these undetected by 1H NMR was explained by the uncorrelated H-transfer.

Nihei, Taka-aki; Ishimaru, Shin'ichi; Ishida, Hiroyuki; Ishihara, Hideta; Ikeda, Ryuichi

2000-10-01

196

Nuclear magnetic resonance studies of quadrupolar nuclei and dipolar field effects  

SciTech Connect

Experimental and theoretical research conducted in two areas in the field of nuclear magnetic resonance (NMR) spectroscopy is presented: (1) studies of the coherent quantum-mechanical control of the angular momentum dynamics of quadrupolar (spin I > 1/2) nuclei and its application to the determination of molecular structure; and (2) applications of the long-range nuclear dipolar field to novel NMR detection methodologies.The dissertation is organized into six chapters. The first two chapters and associated appendices are intended to be pedagogical and include an introduction to the quantum mechanical theory of pulsed NMR spectroscopy and the time dependent theory of quantum mechanics. The third chapter describes investigations of the solid-state multiple-quantum magic angle spinning (MQMAS) NMR experiment applied to I = 5/2 quadrupolar nuclei. This work reports the use of rotary resonance-matched radiofrequency irradiation for sensitivity enhancement of the I = 5/2 MQMAS experiment. These experiments exhibited certain selective line narrowing effects which were investigated theoretically.The fourth chapter extends the discussion of multiple quantum spectroscopy of quadrupolar nuclei to a mostly theoretical study of the feasibility of enhancing the resolution of nitrogen-14 NMR of large biomolecules in solution via double-quantum spectroscopy. The fifth chapter continues to extend the principles of multiple quantum NMR spectroscopy of quadrupolar nuclei to make analogies between experiments in NMR/nuclear quadrupolar resonance (NQR) and experiments in atomic/molecular optics (AMO). These analogies are made through the Hamiltonian and density operator formalism of angular momentum dynamics in the presence of electric and magnetic fields.The sixth chapter investigates the use of the macroscopic nuclear dipolar field to encode the NMR spectrum of an analyte nucleus indirectly in the magnetization of a sensor nucleus. This technique could potentially serve as an encoding module for the recently developed NMR remote detection experiment. The feasibility of using hyperpolarized xenon-129 gas as a sensor is discussed. This work also reports the use of an optical atomic magnetometer to detect the nuclear magnetization of Xe-129 gas, which has potential applicability as a detection module for NMR remote detection experiments.

Urban, Jeffry Todd

2004-12-21

197

Secular resonances. [of asteroidal dynamics  

NASA Technical Reports Server (NTRS)

Theories and numerical experiments regarding secular resonances are reviewed. The basic dynamics and the positions of secular resonances are discussed, and secular perturbation theories for the nu16 resonance case, the nu6 resonance, and the nu5 resonance are addressed. What numerical experiments have revealed about asteroids located in secular resonances, the stability of secular resonances, variations of eccentricities and inclinations, and chaotic orbits is considered. Resonant transport of meteorites is discussed.

Scholl, H.; Froeschle, CH.; Kinoshita, H.; Yoshikawa, M.; Williams, J. G.

1989-01-01

198

On the use of Cramér-Rao minimum variance bounds for the design of magnetic resonance spectroscopy experiments.  

PubMed

Localized Magnetic Resonance Spectroscopy (MRS) is in widespread use for clinical brain research. Standard acquisition sequences to obtain one-dimensional spectra suffer from substantial overlap of spectral contributions from many metabolites. Therefore, specially tuned editing sequences or two-dimensional acquisition schemes are applied to extend the information content. Tuning specific acquisition parameters allows to make the sequences more efficient or more specific for certain target metabolites. Cramér-Rao bounds have been used in other fields for optimization of experiments and are now shown to be very useful as design criteria for localized MRS sequence optimization. The principle is illustrated for one- and two-dimensional MRS, in particular the 2D separation experiment, where the usual restriction to equidistant echo time spacings and equal acquisition times per echo time can be abolished. Particular emphasis is placed on optimizing experiments for quantification of GABA and glutamate. The basic principles are verified by Monte Carlo simulations and in vivo for repeated acquisitions of generalized two-dimensional separation brain spectra obtained from healthy subjects and expanded by bootstrapping for better definition of the quantification uncertainties. PMID:23933043

Bolliger, Christine S; Boesch, Chris; Kreis, Roland

2013-12-01

199

Real sample temperature: a critical issue in the experiments of nuclear resonant vibrational spectroscopy on biological samples  

PubMed Central

There are several practical and intertangled issues which make the experiments of nuclear resonant vibrational spectroscopy (NRVS) on biological samples difficult to perform. The sample temperature is one of the most important issues. In NRVS the real sample temperatures can be very different from the readings on the temperature sensors. In this study the following have been performed: (i) citing and analyzing various existing NRVS data to assess the real sample temperatures during the NRVS measurements and to understand their trends with the samples’ loading conditions; (ii) designing several NRVS measurements with (Et4N)[FeCl4] to verify these trends; and (iii) proposing a new sample-loading procedure to achieve significantly lower real sample temperatures and to balance among the intertangled experimental issues in biological NRVS measurements. PMID:22338688

Wang, Hongxin; Yoda, Yoshitaka; Kamali, Saeed; Zhou, Zhao-Hui; Cramer, Stephen P.

2012-01-01

200

The Fetal Magnetic Resonance Imaging Experience in a Large Community Medical Center  

PubMed Central

Fetal magnetic resonance imaging (MRI) continues to prove a useful problem solving tool for diagnostic and management decision making issues encountered in the antenatal period. In this paper, we attempt to review basic fetal MRI protocol considerations and demonstrate key imaging findings through multiple modalities, with pathologic correlation in several cases. A study of five fetal MRI cases, from our institution, were selected in order to highlight both the indications for, and benefits obtained from this advanced imaging technique. Fetal MRI proved useful in each case in better defining fetal anomalies, especially where ultrasound (due to drawbacks such as shadowing by pelvic bones) was unable to be completely diagnostic. The more in-depth study made possible by MRI also helped with formulation of disease prognosis and estimation of survival chances of the fetus. Further, MRI as a diagnostic and prognostic tool has become more ubiquitous across the medical community. This imparts tangible benefit to patients, who are now able to find this service within arm's reach. Whereas previously these patients were obligatorily referred up to 90 miles away from our centre for further medical work-up, now a large percentage can obtain their prenatal imaging and perinatal care locally. In addition, medical education benefits as new types of cases, those with pathology of the antenatal period, are retained for work-up and management in these large community settings. Cases from our institution exemplify these types of pathologies, from fetal chest masses to a syndromic presentation of bilateral renal agenesis. PMID:21966626

Ghobrial, Peter M; Levy, Rebecca A; O’Connor, Stephen C

2011-01-01

201

A dedicated decay-spectroscopy station for the collinear resonance ionization experiment at ISOLDE  

NASA Astrophysics Data System (ADS)

A new decay-spectroscopy station (DSS) has been developed to be coupled to the collinear resonance ionization spectroscopy (CRIS) beam line at CERN-ISOLDE. The system uses a rotatable wheel with ten 20 ?g/cm2 carbon foils as beam implantation sites for the efficient measurement of charged decay products. Silicon detectors are placed on either side of the carbon foil in an optimal geometry to cover a large solid angle for detecting these charged particles. In addition to the silicon detectors at the on-beam axis position, a second pair of off-beam axis detectors are placed at the wheel position 108° away, allowing longer-lived species to be studied. Up to three high purity germanium detectors can be placed around the chamber for particle-gamma correlated measurement. The radioactive beam is transported through the CRIS beam line before implantation into a carbon foil at the DSS. All materials used in the DSS are UHV-compatible to maintain high vacuum conditions required by the CRIS beam line. This paper describes the DSS and presents the first data collected at the setup during the commissioning run with 221Fr.

Rajabali, M. M.; Lynch, K. M.; Cocolios, T. E.; Billowes, J.; Bissell, M. L.; De Schepper, S.; Dewolf, K.; Flanagan, K. T.; Le Blanc, F.; Marsh, B. A.; Mason, P. J. R.; Matea, I.; Neyens, G.; Papuga, J.; Procter, T. J.; Rothe, S.; Simpson, G. S.; Smith, A. J.; Stroke, H. H.; Verney, D.; Walker, P. M.; Wendt, K.; Wood, R. T.

2013-04-01

202

Avidity of influenza virus: model-based identification of adsorption kinetics from surface plasmon resonance experiments.  

PubMed

Affinity chromatography and membrane adsorption are highly promising methods for the downstream processing of cell culture-derived influenza virus. For the optimization of this separation process, it is desirable to quantify the kinetics of virus adsorption. For this reason, the adsorption kinetics of the influenza A virus (Puerto Rico/8/34 (H1N1)) on a surface with the immobilized ligand Euronymus europaeus lectin (EEL) was investigated. The adsorption kinetics was experimentally monitored in a microfluidic flow cell by surface plasmon resonance (SPR) spectroscopy. The boundary layer theory was applied to analyze the convective and diffusive mass transport of the virus particles in the SPR flow cell. A multi-site kinetic adsorption model was found to describe the experimentally recorded adsorption curves adequately. According to the proposed model, under the applied experimental conditions, the number of sites (galactose residuals) binding one single virus particle to the EEL surface is in the range of 300 to 460, which is in average about 4% of the total number of sites available on the virus surface. The avidity of individual virus particles to the EEL surface was estimated to be in the order of magnitude of 10(6)M(-1)s(-1). PMID:24406143

Wang, Wenjing; Wolff, Michael W; Reichl, Udo; Sundmacher, Kai

2014-01-24

203

Magnetic Resonance-Guided Percutaneous Cryoablation of Uterine Fibroids: Early Clinical Experiences  

SciTech Connect

Purpose. Uterine fibroids (leiomyomas) are the most common tumors of the uterus. The present study evaluated the feasibility and effectiveness of magnetic resonance (MR)-guided percutaneous cryoablation for uterine fibroids as a minimally invasive treatment alternative. Methods. From August 2001 to June 2002, MR-guided percutaneous cryoablation was performed on seven uterine fibroids in 6 patients who displayed clinical symptoms related to tumors. Using a horizontal-type open MR system, cryoablation probes were percutaneously placed in fibroids. Fibroids were ablated, and the site and size of ice balls were monitored on MR imaging. Postoperatively, patients completed a questionnaire to assess changes in presenting clinical symptoms, and MR images were obtained for all patients at follow-up. Changes in clinical symptoms and tumor volume were evaluated in each patient. Results. All treated patients showed reductions in tumor size. Mean volume reduction rate was 40.3% at 6 weeks postoperatively, and 79.4% at 9-12 months. All patients reported fever after treatment. Surgical drainage was required for abscess in the probe channel in one patient, and transient liver damage occurred in another. Subjective symptoms improved in all patients except one who had multiple tumors, and no patient complained of new symptoms after cryoablation during follow-up. Conclusion. MR-guided percutaneous cryoablation represents a feasible and effective treatment for uterine fibroids.

Sakuhara, Yusuke, E-mail: YRB03514@nifty.com; Shimizu, Tadashi; Kodama, Yoshihisa; Sawada, Akihiro [Hokkaido University School of Medicine, Department of Radiology (Japan); Endo, Hideho [Kitami Red Cross Hospital, Department of Radiology (Japan); Abo, Daisuke [Hokkaido University School of Medicine, Department of Radiology (Japan); Hasegawa, Tenshu [Asahikawa Red Cross Hospital, Department of Obstetrics and Gynecology (Japan); Miyasaka, Kazuo [Hokkaido University School of Medicine, Department of Radiology (Japan)

2006-08-15

204

Strong coupling between antiferromagnetic and superconducting order parameters of CeRhIn5 studied by I115n nuclear quadrupole resonance spectroscopy  

NASA Astrophysics Data System (ADS)

We report on a pressure (P) -induced evolution of magnetism and superconductivity (SC) in a helical magnet CeRhIn5 with an incommensurate wave vector Qi=((1)/(2),(1)/(2),0.297) through the I115n nuclear quadrupole resonance (NQR) measurements under P . Systematic measurements of the I115n -NQR spectrum reveal that the commensurate antiferromagnetism (AFM) with Qc=((1)/(2),(1)/(2),(1)/(2)) is realized above Pm˜1.7GPa . An important finding is that the size of SC gap and Tc increase as the magnitude of the AFM moment decreases in the P region, where SC uniformly coexists with the commensurate AFM. This result provides evidence of strong coupling between the commensurate AFM order parameter (OP) and SC OP.

Yashima, M.; Mukuda, H.; Kitaoka, Y.; Shishido, H.; Settai, R.; ?nuki, Y.

2009-06-01

205

Infrared spectroscopic evidence of a redox-dependent conformational change involving ion binding residue NqrB-D397 in the Na(+)-pumping NADH:quinone oxidoreductase from Vibrio cholerae.  

PubMed

The Na(+)-pumping NADH:quinone oxidoreductase (Na(+)-NQR) is a unique respiratory enzyme that conserves energy by translocating Na(+) through the plasma membrane. Found only in prokaryotes, the enzyme serves as the point of entry of electrons into the respiratory chain in many pathogens, including Vibrio cholerae and Yersinia pestis. In this study, a combined electrochemical and Fourier transform infrared (FTIR) spectroscopic approach revealed that Na(+)-NQR undergoes significant conformational changes upon oxidoreduction, depending on the monovalent cation present (Na(+), Li(+), K(+), or Rb(+)). In the presence of the inhibitor Rb(+), additional conformational changes are evident, indicating a changed accessibility of the sodium binding sites. In electrochemically induced FTIR difference spectra, the involvement of deprotonated acid residues in the binding of cations, together with the spectral features, that point toward a monodentate binding mode for these acid residues in the oxidized form of the enzyme and bidentate binding in the reduced form could be identified. The measurements confirmed that NqrB-D397 is one of the acid residues involved in Na(+) and Li(+) binding. In the NqrB-D397E mutant, the spectral features characteristic of COO(-) groups are shifted, and a weakening of the hydrogen binding of the ion binding cluster is revealed. Finally, H-D exchange kinetics of amide protons confirmed that Na(+)-NQR adopts different conformations, with different accessibilities to the aqueous environment, depending on the cation present, which contributes to the selectivity mechanism of ion translocation. PMID:23566241

Neehaul, Yashvin; Juárez, Oscar; Barquera, Blanca; Hellwig, Petra

2013-05-01

206

Patients’ experience of outsourcing and care related to magnetic resonance examinations  

PubMed Central

Background Outsourcing radiological examinations from public university hospitals affects the patient, who has to attend a different clinic or hospital for the radiological examination. We currently have a limited understanding of how patients view outsourcing and their care related to MR examinations. Aim Aim. To examine the experiences of patients who are sent to private radiology units when their referrals for MR examinations are outsourced from a university hospital, as well as to explore factors which influence patient satisfaction regarding the quality of care related to the MR examination. Methods A group of patients (n = 160) referred for MR examinations and either examined at a university hospital or at an external private unit were interviewed. The interview was designed as a verbal questionnaire. Data were analyzed using Student’s t test, analysis of variance (ANOVA), and Pearson’s correlation. Results Sixty-nine percent of the patients could neither choose nor influence the location at which they were examined. For those who could, aspects that influenced the patient’s choice of radiology department were: short waiting time 79% (127/160), ease of traveling to the radiology department 68% (110/160), and short distance to their home or work 58% (93/160). For 40% (60/160) of the patients, a short time in the waiting room was related to a positive experience of the MR examination. Conclusion Conclusion. If patients were informed about outsourcing and could also choose where to have their examination, key factors contributing to patient satisfaction could be met even when MR examinations are outsourced. PMID:25142133

Aspelin, Peter; Bergstrand, Lott; Blomqvist, Lennart

2014-01-01

207

Study of plasma start-up initiated by second harmonic electron cyclotron resonance heating on WEGA experiment  

SciTech Connect

Although both 1st harmonic ordinary mode (O1) and 2nd harmonic extra-ordinary mode (X2) have been successfully used to initiate pre-ionization and breakdown in many devices, a complete theoretical model is still missing to explain the success of this method. Moreover, some experimental observations are not completely understood, such as what occurs during the delay time between the turn-on of ECRH power and first signals of density or light measurements. Since during this free period the ECRH power has to be absorbed by in-vessel components, it is of prime importance to know what governs this delay time. Recently, dedicated start-up experiments have been performed on WEGA, using a 28 GHz ECRH system in X2-mode. This machine has the interesting capability to be run also as a tokamak allowing comparative experiments between stellarator (?/2? > 0) and tokamak (?/2? = 0) configurations. Different scans in heating power, neutral gas pressure, and rotational transform (?) show clearly that the start-up is a two step process. A first step following the turn-on of the ECRH power during which no measurable electron density (or just above the noise level in some cases), ECE and radiated power is detected. Its duration depends strongly on the level of injected power. The second step corresponds to the gas ionization and plasma expansion phase, with a velocity of density build-up and filling-up of the vessel volume depending mainly on pressure, gas and rotational transform. Moreover, an interesting scenario of ECRH pre-ionization without loop voltage in tokamak configuration by applying a small optimal vertical field is relevant for start-up assistance on future experiments like ITER. The results from this experimental parametric study are useful for the modeling of the start-up assisted by the second harmonic electron cyclotron resonance heating. The aim of this work is to establish predictive scenarios for both ITER and W7-X operation.

Preynas, M.; Laqua, H. P.; Otte, M.; Stange, T.; Aßmus, D. [Max Planck Institut für Plasmaphysik, EURATOM Association, D-17491 Greifswald (Germany); Wauters, T. [Association Euratom-Belgian State, LPP-ERM/KMS, 1000 Brussels (Belgium)

2014-02-12

208

Study of plasma start-up initiated by second harmonic electron cyclotron resonance heating on WEGA experiment  

NASA Astrophysics Data System (ADS)

Although both 1st harmonic ordinary mode (O1) and 2nd harmonic extra-ordinary mode (X2) have been successfully used to initiate pre-ionization and breakdown in many devices, a complete theoretical model is still missing to explain the success of this method. Moreover, some experimental observations are not completely understood, such as what occurs during the delay time between the turn-on of ECRH power and first signals of density or light measurements. Since during this free period the ECRH power has to be absorbed by in-vessel components, it is of prime importance to know what governs this delay time. Recently, dedicated start-up experiments have been performed on WEGA, using a 28 GHz ECRH system in X2-mode. This machine has the interesting capability to be run also as a tokamak allowing comparative experiments between stellarator (?/2? > 0) and tokamak (?/2? = 0) configurations. Different scans in heating power, neutral gas pressure, and rotational transform (?) show clearly that the start-up is a two step process. A first step following the turn-on of the ECRH power during which no measurable electron density (or just above the noise level in some cases), ECE and radiated power is detected. Its duration depends strongly on the level of injected power. The second step corresponds to the gas ionization and plasma expansion phase, with a velocity of density build-up and filling-up of the vessel volume depending mainly on pressure, gas and rotational transform. Moreover, an interesting scenario of ECRH pre-ionization without loop voltage in tokamak configuration by applying a small optimal vertical field is relevant for start-up assistance on future experiments like ITER. The results from this experimental parametric study are useful for the modeling of the start-up assisted by the second harmonic electron cyclotron resonance heating. The aim of this work is to establish predictive scenarios for both ITER and W7-X operation.

Preynas, M.; Laqua, H. P.; Otte, M.; Stange, T.; Wauters, T.; Aßmus, D.

2014-02-01

209

Field experiment provides ground truth for surface nuclear magnetic resonance measurement  

USGS Publications Warehouse

The need for sustainable management of fresh water resources is one of the great challenges of the 21st century. Since most of the planet's liquid fresh water exists as groundwater, it is essential to develop non-invasive geophysical techniques to characterize groundwater aquifers. A field experiment was conducted in the High Plains Aquifer, central United States, to explore the mechanisms governing the non-invasive Surface NMR (SNMR) technology. We acquired both SNMR data and logging NMR data at a field site, along with lithology information from drill cuttings. This allowed us to directly compare the NMR relaxation parameter measured during logging, T 2, to the relaxation parameter T 2 * measured using the SNMR method. The latter can be affected by inhomogeneity in the magnetic field, thus obscuring the link between the NMR relaxation parameter and the hydraulic conductivity of the geologic material. When the logging T 2 data were transformed to pseudo-T 2 * data, by accounting for inhomogeneity in the magnetic field and instrument dead time, we found good agreement with T 2 * obtained from the SNMR measurement. These results, combined with the additional information about lithology at the site, allowed us to delineate the physical mechanisms governing the SNMR measurement. Such understanding is a critical step in developing SNMR as a reliable geophysical method for the assessment of groundwater resources. Copyright 2012 by the American Geophysical Union.

Knight, R.; Grunewald, E.; Irons, T.; Dlubac, K.; Song, Y.; Bachman, H.N.; Grau, B.; Walsh, D.; Abraham, J.D.; Cannia, J.

2012-01-01

210

Oxygen isotope effect of the plane-copper NQR frequency in YBa2Cu4O8  

NASA Astrophysics Data System (ADS)

We report high-precision measurements of the temperature dependence of the plane-63Cu NQR line frequency ?Q(Cu2) and the linewidth in normal and superconducting 16O and 18O-exchanged YBa2Cu4O8. Whereas ?Q(Cu2) passes Tc very smoothly without a discontinuity either in value or slope, the linewidth increases in the normal conducting phase down to Tc and starts to decrease sharply in the superconducting phase to finally resume its high-temperature value of the normal phase. There is a well discernible oxygen isotope effect on the ?Q(Cu2) temperature dependencies. The temperature dependence of ?Q(Cu2) is described by an empirical expression consisting of two parts, one related to the thermal expansion of the lattice and the other due to charge redistribution during the formation of new electronic structures in the CuO2 planes. From the fit to the experimental data we determine for the conjectured formation of new electronic structures an energy scale ?(16O)=188.0(1.6) K and ?(18O)=180.0(1.6) K. This results in a partial oxygen isotope effect coefficient ??Q=0.42(11) which is larger than both the spin pseudogap coefficient ?PG=0.061(8) and the Tc coefficient ?Tc=0.056(12) [F. Raffa, T. Ohno, M. Mali, J. Roos, D. Brinkmann, K. Conder, and M. Eremin, Phys. Rev. Lett. 81, 5912 (1998)].

Mali, M.; Roos, J.; Keller, H.; Karpinski, J.; Conder, K.

2002-05-01

211

Field-tuned critical fluctuations in YFe2Al10: Evidence from magnetization, 27Al NMR, and NQR investigations  

NASA Astrophysics Data System (ADS)

We report magnetization, specific heat, and NMR investigations on YFe2Al10 over a wide range of temperature and magnetic field and zero field (NQR) measurements. Magnetic susceptibility, specific heat, and spin-lattice relaxation rate divided by T(1/T1T) follow a weak power law (˜T-0.4) temperature dependence, which is a signature of the critical fluctuations of Fe moments. The value of the Sommerfeld-Wilson ratio and the linear relation between 1/T1T and ? suggest the existence of ferromagnetic correlations in this system. No magnetic ordering down to 50 mK in Cp(T)/T and the unusual T and H scaling of the bulk and NMR data are associated with a magnetic instability which drives the system to quantum criticality. The magnetic properties of the system are tuned by field wherein ferromagnetic fluctuations are suppressed and a crossover from quantum critical to Fermi-liquid behavior is observed with increasing magnetic field.

Khuntia, P.; Strydom, A. M.; Wu, L. S.; Aronson, M. C.; Steglich, F.; Baenitz, M.

2012-12-01

212

Technical challenges in 3 T magnetic resonance spectroscopic imaging of the prostate—A single-institution experience  

PubMed Central

The magnetic resonance spectroscopic imaging (MRSI) is the only technique that is currently available in the clinical practice to provide the metabolic status of prostate tissue at the cellular level with a great potential to improve the clinical patient care. Increasing the field strength from 1.5 to 3 T can theoretically provide proportionately higher signal-to-noise ratio (SNR) and improve spectral separation between prostatic metabolite peaks. The technique, however, has been limited to a few academic institutions that are equipped with a team of experts primarily due to due to serious technical challenges in optimizing the spectral quality. High quality shimming is key to the successful MRSI acquisition. Without optimization of the increased field inhomogeneity and radiofrequency (RF) dielectric effect at 3 T, the spectral peak broadening and residual signal from the periprostatic fat tissue may render the overall spectra non-diagnostic. The purpose of this technical note is to present the practical steps of successful acquisition of 3 T MRSI and to address several important technical challenges in minimizing the effect of the increased magnetic field and RF field inhomogeneity in order to obtain highest possible spectral quality based on our initial experience in using 3 T MRSI prototype software. PMID:25202660

Underwood, Michelle; Boonsirikamchai, Piyaporn; Matin, Surena; Troncoso, Patricia; Ma, Jingfei

2014-01-01

213

Application of quantitative (19) F nuclear magnetic resonance spectroscopy in tape-stripping experiments with natural microemulsions.  

PubMed

The skin penetration of flufenamic acid (Fluf) and fluconazole (Fluc) from innovative natural microemulsions was investigated in tape-stripping experiments on pig ears. The formulations were based on the eudermic surfactants lecithin, sucrose laurate, alkylpolyglycoside or a mixture thereof. The quantification of the penetrated drug amounts was executed by (19) F nuclear magnetic resonance (NMR) in comparison with high-performance liquid chromatography (HPLC). The data obtained by the (19) F NMR method were confirmed by additional quantitative studies using HPLC. An excellent linear correlation was found for Fluf as well as for Fluc between (19) F NMR and HPLC data. This work presents a strategy outlining the use of (19) F NMR to selectively monitor the skin penetration routes of fluorinated compounds. Fluc penetrated generally well into the stratum corneum with the significantly highest amounts from the sucrose laurate microemulsion on the tape strips 1-5. Similarly, the highest amounts of penetrated Fluf could be observed from the formulation based on sucrose laurate. In addition, NMR self-diffusion studies were conducted and revealed a bicontinuous microstructure of the investigated microemulsions. The skin penetration results are in good agreement with the obtained (19) F NMR self-diffusion coefficients of the active compounds in the microemulsion systems. PMID:23794482

Schwarz, Julia C; Hoppel, Magdalena; Kählig, Hanspeter; Valenta, Claudia

2013-08-01

214

NQR-NMR studies of higher alcohol synthesis Cu-Co catalysts  

SciTech Connect

Copper and cobalt are the key elements in syngas conversion catalyst systems used for higher alcohol synthesis. Their proximity and synergy sensitively control the selectivity and efficiency of the process. It is believed that their outer electronic charge distribution which is responsible for their electrical and magnetic properties might be governing their catalytic properties also. To examine the correlation between catalytic and magnetic properties, a series of copper cobalt catalysts (Co/Cu ratio 5:1 to 5:5) with and without a support were prepared. The nuclear quadrupole resonance spectrum of copper and (zero-field) nuclear magnetic resonance spectrum of cobalt and magnetization and hysteresis character of the catalyst were analyzed. Similar to the catalytic results, the magnetic results also were found to be very sensitive to the preparation technique. The results indicate possible electron exchange between copper and cobalt, and cobalt and the support Titania.

Not Available

1991-01-14

215

Pulsed Fourier-transform NQR of sup 14 N with a dc SQUID  

SciTech Connect

The zero-field free induction decay of solid ammonium perchlorate at 1.5 K has been directly detected with a dc superconducting quantum interference device. The Fourier-transform spectrum consists of three sharp lines at 17.4, 38.8, and 56.2 kHz arising from pure {sup 14}N nuclear quadrupole resonance transitions. The absence of splittings and resonance transitions from dipolar-coupled proton spins is attributed to reorientation of the ammonium groups by quantum tunneling in combination with motional averaging in the three proton levels characterized by the irreducible representation {ital T}. The measured {sup 14}N spin-spin relaxation time is 22{plus minus}2 ms and the spin-lattice relaxation time is 63{plus minus}6 ms.

Huerlimann, M.D.; Pennington, C.H.; Fan, N.Q.; Clarke, J.; Pines, A.; Hahn, E.L. (Department of Physics, University of California, Berkeley, Berkeley, California 94720 (United States) Department of Chemistry, University of California, Berkeley, Berkeley, California 94720 (United States) Materials Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States))

1992-07-27

216

J-Substitution Algorithm in Magnetic Resonance Electrical Impedance Tomography (MREIT): Phantom Experiments for Static Resistivity Images  

Microsoft Academic Search

Recently, a new static resistivity image reconstruction algorithm is proposed utilizing internal current density data obtained by magnetic resonance current density imaging technique. This new imaging method is called magnetic resonance electrical impedance tomography (MREIT). The derivation and performance of J-substitution algorithm in MREIT have been reported as a new accurate and high-resolution static impedance imaging technique via computer simulation

Hyan Soo Khang; Byung Il Lee; Suk Hoon Oh; Eung Je Woo; Soo Yeol Lee; Min Hyoung Cho; Ohin Kwon; Jeong-rock Yoon; Jin Keun Seo

2002-01-01

217

Nuclear Quadrupole Resonance Studies of the Sorc Sequence and Nuclear Magnetic Resonance Studies of Polymers.  

NASA Astrophysics Data System (ADS)

The behavior of induction signals during steady -state pulse irradiation in ^{14} N NQR was investigated experimentally. Because Strong Off-resonance Comb (SORC) signals recur as long as the pulsing continues, very efficient signal-averaging can result. The dependence of these steady-state SORC signals on pulse parameters and on frequency offset are presented, together with a discussion of the applicability of the method. Also as part of the NQR work, Cocaine base has been detected using conventional NQR techniques. The experimental results show that SORC detection can be of sufficient sensitivity to form the basis of narcotics screening devices for both mail and airline baggage. A new NMR technique, to obtain the correlation time of the random thermal motion of a polymer at temperatures near the glass transition has been introduced. The temperature dependence is a result of thermal motion. For slow-motion of a polymer chain near the glass transition, the CSA parameter begins to decrease. This motional narrowing can be interpreted to yield the correlation time of the thermal motion. In this work Nitrocellulose isotopically highly enriched with ^{15}N was studied at four different temperatures between 27^ circ and 120^circ Celsius and the correlation times for polymer backbone motions were obtained. Nafion films containing, water (D_2 O and H_2^{17}O) and methanol (CH_3OD, CH _3^{17}OH), have been studied using Deuteron and Oxygen-17 NMR spectroscopy. Glassy behavior of the water domains at low temperature is evidenced by the specific nature of the ^2H NMR lineshapes. Activation energies extracted from ^2H spin-lattice relaxation data on the high temperature side of the T_1 minimum exhibit a steady increase with increasing water content. In spite of a high degree of molecular mobility, angular-dependent spectra of both unstretched and stretched samples reflect considerable anisotropy of the host polymer. Activation volumes corresponding to a specific dynamical process were obtained from measurements of spin-lattice relaxation vs. pressure. From the NMR measurements of Nafion films containing methanol, it was found that the molecular motion is much more rapid than the molecular motion of water in Nafion membranes.

Jayakody, Jayakody R. Pemadasa

1993-01-01

218

Quantification of microdamage in slate tiles: Comparison of nonlinear acoustic resonance experiments with visual and x-ray diagnosis  

NASA Astrophysics Data System (ADS)

Single Mode Nonlinear Resonant Acoustic Spectroscopy (SIMONRAS) is applied to detect edgecracks in thin slate roofing tiles. The technique focuses on the acoustic nonlinear (i.e. amplitude dependent) response of a particular resonance mode of the material when driven at relatively small wave amplitudes. Undamaged materials are essentially linear in their resonant response. The same material, however, becomes highly nonlinear when cracked. The sensitivity of this method to discern damage due to edgecracking is compared to visual diagnosis of crack density and X-ray images of cracks.

Van Den Abeele, K.; Carmeliet, J.; Wevers, M.

2000-07-01

219

Resonance absorption in CO2 laser-plane targets interaction experiments C. Garban-Labaune, E. Fabre, F. David, J. Maignan and A. Michard  

E-print Network

L-463 Resonance absorption in CO2 laser-plane targets interaction experiments C. Garban-Labaune, E) Résumé. 2014 Nous avons étudié l'influence de la polarisation et de l'angle d'incidence sur l'absorption des flux de 5 x 1011- 5 1012 W/cm2. Les mesures d'absorption sont obtenues à partir de la mesure

Boyer, Edmond

220

Utilization of pure nuclear quadrupole resonance spectroscopy for the study of pharmaceutical crystal forms.  

PubMed

Solid-state physical characterization of a pharmaceutical substance is necessary for successful development and approval of the final product. Different physical analytical techniques are available to do so: X-ray diffraction (XRD), IR, Raman, DSC, TG and NMR. Moreover, all of them detect the presence of excipients perturbing the analysis of the pure substance in low doses. In order to study polymorphism and pseudo polymorphism of drug, this paper introduces possible applications of pure nuclear quadrupole resonance, as a non-destructive technique in qualitative and quantitative approaches. Chlorpropamide and diclofenac sodium were used as examples. Unlike the mentioned techniques, the nuclear quadrupole resonance (NQR) signal of pharmaceutical compounds is not perturbed by the presence of solid excipient or other substances unless they possess resonance frequencies in the same frequency range of the compound studied. PMID:15913931

Pérez, S C; Cerioni, L; Wolfenson, A E; Faudone, S; Cuffini, S L

2005-07-14

221

Experiments of high-amplitude and shock-free oscillations of air column in a tube with array of Helmholtz resonators  

NASA Astrophysics Data System (ADS)

This experimental study is made to verify the weakly nonlinear theory for high-amplitude and shock-free oscillations of an air column developed in the previous paper [Sugimoto et al., J. Acoust. Soc. Am., 114, 1772-1784 (2003)]. The experiments use a new tube and resonators designed so as to not only avoid higher harmonic resonances and evanescences but also reduce the values of the coefficient of Q in the amplitude equation, and a rubber diaphragm sandwiched by circular plates to drive the air column. The steady-state pressure field in the tube and in the cavities of the resonators is measured, from which Fourier coefficients are obtained. In spite of nonlinearity, higher harmonics are suppressed significantly as designed, and the frequency response measured shows quantitatively good agreement with the one predicted up to about 170 dB (SPL). The first harmonics and the nonoscillatory component in the pressure field are well predicted, though the second harmonics show a quantitative discrepancy with the theory. In view of the good agreement of the frequency response, it is concluded that the theory is valid and useful enough to provide guidelines in designing the tube with the array of resonators.

Masuda, M.; Sugimoto, N.

2005-07-01

222

Normal state spin susceptibility in YBa 2Cu 3O 6.92 single crystal from 63Cu and 89Y nuclear magnetic resonance  

NASA Astrophysics Data System (ADS)

We present an extensive nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) study of the normal state ( T> Tc) of an YBa 1.93Sr 0.07Cu 3O 6.92 single crystal ( Tc=90 K). The NMR data is interpreted using a model for the imaginary part of the dynamical electron spin susceptibility ??( q, ?) that is consistent with the inelastic neutron scattering (INS) experiments (carried out on the same sample investigated here): the q-dependence is assumed to be Gaussian (commensurate), with short and T independent coherence length ?. This model enabled us to perform a quantitative analysis of the planar copper spin-lattice and spin-spin relaxation rates which evidenced that a spin pseudogap starts to open at T*?130 K, confirming the INS results. Moreover, we show that the AF fluctuations contribution to yttrium relaxation is not negligible due to the dipolar coupling of the yttrium with the neighboring copper spins. The main signature of this feature is that a relation K??T1T=const does not hold for the yttrium site at higher temperatures. Our main conclusion is that, in order to explain the yttrium (and the planar oxygen) relaxation coherently with the INS results and the widely accepted one-band picture, the characteristic energy ?0 of the spin dynamics near q=0 must be strongly T dependent, otherwise the one-band description is not feasible. All the NMR results are interpreted within the ionic model of the hyperfine Hamiltonian taking into account the anisotropy of the g-factor and the static spin susceptibility ?s.

Auler, T.; Horvatic, M.; Gillet, J. A.; Berthier, C.; Berthier, Y.; Carretta, P.; Kitaoka, Y.; Ségransan, P.; Henry, J. Y.

1999-02-01

223

Tumor Resection in a Shared-Resource Magnetic Resonance Operating Room: Experience at the University of Cincinnati  

Microsoft Academic Search

\\u000a \\u000a Introduction. At the University of Cincinnati, we have developed a shared-resource magnetic resonance operating suite that facilitates\\u000a performance of both neurosurgical and diagnostic procedures in a single unit.\\u000a \\u000a \\u000a \\u000a Methods. The shared-resource magnetic resonance operating suite utilizes a Hitachi AIRIS II, 0.3-T, vertical field, open MRI unit\\u000a located in the MROR. This magnet can be used for both diagnostic and interventional

C. M. McPherson; R. J. Bohinski; E. Dagnew; R. E. Warnick; J. M. Tew

224

Long-lived frequency shifts observed in a magnetic resonance force microscope experiment following microwave irradiation of a nitroxide spin probe  

PubMed Central

We introduce a spin-modulation protocol for force-gradient detection of magnetic resonance that enables the real-time readout of longitudinal magnetization in an electron spin resonance experiment involving fast-relaxing spins. We applied this method to observe a prompt change in longitudinal magnetization following the microwave irradiation of a nitroxide-doped perdeuterated polystyrene film having an electron spin-lattice relaxation time of T1?1ms. The protocol allowed us to discover a large, long-lived cantilever frequency shift. Based on its magnitude, lifetime, and field dependence, we tentatively attribute this persistent signal to deuteron spin magnetization created via transfer of polarization from nitroxide spins. PMID:23653485

Chen, Lei; Longenecker, Jonilyn G.; Moore, Eric W.; Marohn, John A.

2013-01-01

225

?-detected nuclear quadrupole resonance and relaxation of 8Li+ in sapphire  

NASA Astrophysics Data System (ADS)

We report detailed behaviour of low energy 8Li implanted near the surface of ?- Al2O3 single crystal, as revealed by beta-detected NQR of 8Li. We find that the implanted 8Li occupies at least two sites with non-cubic symmetry in the Al2O3 lattice. In both sites the 8Li experiences axially symmetric electric field gradient, with the main principal axis along the c-crystallographic direction. The temperature and field dependence of the spin lattice relaxation of 8Li in ?-Al2O3, indicate that the 8Li diffusion is negligible on the scale of its lifetime, 1.21 s.

Salman, Z.; Chow, K. H.; Hossain, M. D.; Kiefl, R. F.; Levy, C. D. P.; Parolin, T. J.; Pearson, M. R.; Saadaoui, H.; Wang, D.; MacFarlane, W. A.

2014-12-01

226

Signature of the seasonal migration of global lightning in the variation of Schumann resonance peak frequencies - Theory versus experiment  

Microsoft Academic Search

The distance between the active lightning sources and a fixed receiver changes when the global lightning migrates northward\\/southward over the year. Schumann resonance (SR) peak frequencies depend on both the source-observer geometry and the propagation conditions in the Earth-ionosphere cavity. The source-observer geometry can be manifest in frequency variations with different signs for the different modes and field components. This

Gabriella Sátori; Vadim Mushtak; Earle Williams; Tamás. Nagy

2010-01-01

227

Dark resonance  

SciTech Connect

We construct explicit models of particle dark matter where the attractive force in the dark matter sector creates a narrow near-threshold resonance that qualitatively changes the energy dependence of the annihilation cross section. In these models, the resonant enhancement of the dark matter annihilation can easily source the excess of energetic leptons observed by the PAMELA experiment. The distinct feature of these models is that by construction the enhancement of the annihilation cross section shuts off when the dark matter velocity falls below the typical Milky Way values, thus automatically satisfying constraints on dark matter annihilation imposed by the CMB anisotropies and gamma ray constraints from satellite galaxies. However, the resonant enhancement of annihilation can be probed through the most recent FERMI-LAT constraints on the diffuse galactic gamma ray emission.

An, Haipeng; Pospelov, Maxim, E-mail: han@perimeterinstitute.ca, E-mail: mpospelov@perimeterinstitute.ca [Perimeter Institute for Theoretical Physics, Waterloo, ON, N2J 2W9 (Canada)

2012-11-01

228

Isotope ratio of Cl NQR spin-lattice relaxation times in 1D hydrogen-bonding system of tetramethylpyrazine-chloranilic acid at high temperatures  

NASA Astrophysics Data System (ADS)

The temperature dependences of spin-lattice relaxation time T 1 of 35Cl and 37Cl NQR were studied for the co-crystal of tetramethylpyrazine (TMP) with chloranilic acid (H2ca), TMP-H2ca, in which one-dimensional hydrogen bonding is formed by alternate arrangement of TMP and H2ca. The isotope ratio 37Cl T 1 / 35Cl T 1 was determined to be 1.0 ± 0.1 above ca. 290 K where a steep decrease of spin-lattice relaxation time T 1 with increasing temperature was observed. In this temperature range it is suggested that the relaxation is originated from the slow fluctuation of electric field gradient (EFG). Beside EFG fluctuation due to the external-charge-density fluctuation, the small angle reorientation of the quantization axis triggered by a proton transfer motion between N...H-O and N-H...O hydrogen bonding states is proposed.

Asaji, Tetsuo

2013-05-01

229

Experiments  

NASA Astrophysics Data System (ADS)

Experiments were performed on the CERN cyclotron. Pion capture in Ta, Re, and Bi, quadrupole moments, nuclear gamma transitions, pion absorption in the nucleus, neutron multiplicity and angular momentum, and charged particles emission after pion absorption were studied.

Konijn, J.

230

Hydrogen bonding and proton transfer in cocrystals of 4,4'-bipyridyl and organic acids studied using nuclear quadrupole resonance.  

PubMed

Cocrystals of 4,4'-bipyridyl and several carboxylic acids were grown from the methanol solution of the cocrystal formers. Complete (14)N NQR spectra of these cocrystals have been measured using (1)H-(14)N nuclear quadrupole double resonance. The principal values of the quadrupole coupling tensor are calculated from the (14)N NQR frequencies. A large variation in the (14)N quadrupole coupling constant between 1.3 MHz and 4.7 MHz is observed. A very low (14)N quadrupole coupling constant, characteristic for proton transfer O-H···N ? O(-)···H-N(+), is observed in 4,4'-bipyridyl-oxalic acid (1?:?1). In 4,4'-bipyridyl-5-chlorosalycilic acid (1?:?1) the (14)N NQR data show the presence of a short, strong N···H···O hydrogen bond. A correlation of the principal values of the (14)N quadrupole coupling tensor is observed. The correlation is analyzed in the model, where the deformation of the lone pair electron orbital and the change of the population of the ?-electron orbital produce the variation of the (14)N quadrupole coupling tensor in the hydrogen bonded 4,4'-bipyridyl. The temperature variation of the (14)N quadrupole coupling tensor in 4,4'-bipyridyl-5-chlorosalycilic acid (1?:?1) is analyzed. Proton displacement within the N···H···O hydrogen bond and the change of the population of the ?-electron orbital at the two nitrogen positions in a 4,4'-bipyridyl molecule in the temperature interval between 157 K and 323 K are determined. PMID:25052623

Seliger, Janez; Žagar, Veselko

2014-09-14

231

C N.M.R. and N N.Q.R. in ferroelectric liquid crystals Polar versus quadrupolar ordering  

Microsoft Academic Search

C nuclear magnetic resonance and N nuclear quadrupole resonance spectra of ferroelectric smectic C*liquid crystals and their non-chiral analogues allow for a microscopic determination of the polar and quadrupolar (or bipolar) biasing of rotation around the long molecular axis as well as for a determination of the anisotropy in the fluctuations of this axis. The results show that the microscopic

R. Blinc; J. Dolinšek; M. Luzar; J. Seliger

1988-01-01

232

Experiments on whistler mode electron-cyclotron resonance plasma startup and heating in an axisymmetric magnetic mirror  

SciTech Connect

Whistler mode electron-cyclotron resonance heating (ECRH) has been performed simultaneously with whistler mode electron-cyclotron emission measurements on an axisymmetric magnetic mirror plasma. Results presented include a study of the early plasma startup phase and two instability phases, one believed to be caused by a whistler instability and another by magnetohydrodynamic (MHD) flute instability. Enhanced microwave emission at frequencies below the midplane electron-cyclotron frequency has been correlated with enhanced electron endloss during the whistler instability. Cyclotron emission spectra during the startup phase match predictions for a ''sloshing electron'' type distribution based on numerical modeling. This distribution also agrees with anisotropic distributions resulting from electron-cyclotron heating as predicted by Fokker--Planck computer simulations. Experimentally measured heating rates show good agreement with simplified analytical models based on stochastic heating.

Booske, J.H.; Getty, W.D.; Gilgenbach, R.M.; Jong, R.A.

1985-10-01

233

A multi-sample changer coupled to an electron cyclotron resonance source for accelerator mass spectrometry experiments.  

PubMed

A new multi-sample changer has been constructed allowing rapid changes between samples. The sample changer has 20 positions and is capable of moving between samples in 1 min. The sample changer is part of a project using Accelerator Mass Spectrometry (AMS) at the Argonne Tandem Linac Accelerator System (ATLAS) facility to measure neutron capture rates on a wide range of actinides in a reactor environment. This project will require the measurement of a large number of samples previously irradiated in the Advanced Test Reactor at Idaho National Laboratory. The AMS technique at ATLAS is based on production of highly charged positive ions in an electron cyclotron resonance ion source followed by acceleration in the ATLAS linac. The sample material is introduced into the plasma via laser ablation chosen to limit the dependency of material feed rates upon the source material composition as well as minimize cross-talk between samples. PMID:24593487

Vondrasek, R; Palchan, T; Pardo, R; Peters, C; Power, M; Scott, R

2014-02-01

234

A multi-sample changer coupled to an electron cyclotron resonance source for accelerator mass spectrometry experiments  

NASA Astrophysics Data System (ADS)

A new multi-sample changer has been constructed allowing rapid changes between samples. The sample changer has 20 positions and is capable of moving between samples in 1 min. The sample changer is part of a project using Accelerator Mass Spectrometry (AMS) at the Argonne Tandem Linac Accelerator System (ATLAS) facility to measure neutron capture rates on a wide range of actinides in a reactor environment. This project will require the measurement of a large number of samples previously irradiated in the Advanced Test Reactor at Idaho National Laboratory. The AMS technique at ATLAS is based on production of highly charged positive ions in an electron cyclotron resonance ion source followed by acceleration in the ATLAS linac. The sample material is introduced into the plasma via laser ablation chosen to limit the dependency of material feed rates upon the source material composition as well as minimize cross-talk between samples.

Vondrasek, R.; Palchan, T.; Pardo, R.; Peters, C.; Power, M.; Scott, R.

2014-02-01

235

High-frequency ESR measurements and ESR/NMR double resonance experiments of lightly phosphorous-doped silicon  

NASA Astrophysics Data System (ADS)

We studied lightly doped Si:P with high-frequency (80-120 GHz) ESR and ESR/NMR double magnetic resonance techniques in the temperature range down to 1.4 K. We found dynamic nuclear polarization of 31P from steady-state ESR measurements with approximately 3.6 T. We derived the nuclear spin relaxation time, T1N, of 31P by analysing the time-evolution of ESR spectra utilizing the dynamic nuclear polarization effect. We derive temperature and magnetic field dependence of T1N and compare with experimental data. Furthermore, from our ESR measurements, we modulate the nuclear polarization of 31P by applying an RF field.

Fujii, Y.; Mitsudo, S.; Morimoto, K.; Mizusaki, T.; Gwak, M.; Lee, S. G.; Fukuda, A.; Matsubara, A.; Ueno, T.; Lee, S.

2014-12-01

236

Small and Large Angle Quasi-Elastic Scattering Experiments by Using Nuclear Resonant Scattering on Typical and Amphiphilic Liquid Crystals  

NASA Astrophysics Data System (ADS)

The microscopic slow dynamics with a time scale of around 100 ns in soft matters is important for understanding the origins of their mesoscopic structures. However, it is difficult to observe the slow dynamics at the microscopic level. Here, a newly developed time-domain interferometry (TDI) method using nuclear resonant scattering was applied to study the microscopic dynamics in a typical liquid crystal 4-cyano-4'-octylbiphenyl (8CB) and a partly fluorinated amphiphilic liquid crystal 11-(4'-cyanobiphenyl-4-yloxy)undecyl pentadecafluorooctanoate (BI) under a smectic A phase. As a result, the relaxation times of the molecular correlations in the intersmectic and intrasmectic layers could be obtained simultaneously by the TDI method and similar degrees of the anisotropic dynamical behaviour of 8CB and BI were observed.

Saito, Makina; Seto, Makoto; Kitao, Shinji; Kobayashi, Yasuhiro; Kurokuzu, Masayuki; Yoda, Yoshitaka; Yamamoto, Jun

2012-02-01

237

Nondestructive testing of adhesive bonds by nuclear quadrupole resonance method  

NASA Technical Reports Server (NTRS)

Inert, strain sensitive tracer, cuprous oxide, added to polymeric adhesive ensures sufficiently large signal to noise ratio in NQR system output. Method is successful, provided that RF-transparent structural materials are used between modified adhesive and probe of NQR spectrometer.

Hewitt, R. R.

1971-01-01

238

Resonances and resonance widths  

SciTech Connect

Two-dimensional betatron resonances are much more important than their simple one-dimensional counterparts and exhibit a strong dependence on the betatron phase advance per cell. A practical definition of ''width'' is expanded upon in order to display these relations in tables. A primarily pedagogical introduction is given to explain the tables, and also to encourage a wider capability for deriving resonance behavior and wider use of ''designer'' resonances.

Collins, T.

1986-05-01

239

In vivo (31)P magnetic resonance spectroscopy of the human liver at 7?T: an initial experience.  

PubMed

Phosphorus ((31) P) MRS is a powerful tool for the non-invasive investigation of human liver metabolism. Four in vivo (31) P localization approaches (single voxel image selected in vivo spectroscopy (3D-ISIS), slab selective 1D-ISIS, 2D chemical shift imaging (CSI), and 3D-CSI) with different voxel volumes and acquisition times were demonstrated in nine healthy volunteers. Localization techniques provided comparable signal-to-noise ratios normalized for voxel volume and acquisition time differences, Cramer-Rao lower bounds (8.7?±?3.3%1D-ISIS , 7.6?±?2.5%3D-ISIS , 8.6?±?4.2%2D-CSI , 10.3?±?2.7%3D-CSI ), and linewidths (50?±?24 Hz1D-ISIS , 34?±?10 Hz3D-ISIS , 33?±?10 Hz2D-CSI , 34?±?11 Hz3D-CSI ). Longitudinal (T1 ) relaxation times of human liver metabolites at 7?T were assessed by 1D-ISIS inversion recovery in the same volunteers (n?=?9). T1 relaxation times of hepatic (31) P metabolites at 7?T were the following: phosphorylethanolamine - 4.41?±?1.55?s; phosphorylcholine - 3.74?±?1.31?s; inorganic phosphate - 0.70?±?0.33?s; glycerol 3-phosphorylethanolamine - 6.19?±?0.91?s; glycerol 3-phosphorylcholine - 5.94?±?0.73?s; ?-adenosine triphosphate (ATP) - 0.50?±?0.08?s; ?-ATP - 0.46?±?0.07?s; ?-ATP - 0.56?±?0.07?s. The improved spectral resolution at 7?T enabled separation of resonances in the phosphomonoester and phosphodiester spectral region as well as nicotinamide adenine dinucleotide and uridine diphosphoglucose signals. An additional resonance at 2.06?ppm previously assigned to phosphoenolpyruvate or phosphatidylcholine is also detectable. These are the first (31) P metabolite relaxation time measurements at 7?T in human liver, and they will help in the exploration of new, exciting questions in metabolic research with 7?T MR. PMID:24615903

Chmelik, Marek; Považan, Michal; Krššák, Martin; Gruber, Stephan; Tka?ov, Martin; Trattnig, Siegfried; Bogner, Wolfgang

2014-04-01

240

1. First coincidence experiments between cryogenic resonant-mass gravitational-wave detectors. 2. Development of a thin-film superconducting transducer for a gravitational-wave antenna  

SciTech Connect

This dissertation is concerned with two aspects of detecting gravitational radiation from astrophysical sources. First, the data collection and analysis for a coincidence experiment conducted in 1986 using gravitational wave detectors operated by Stanford University, the university of Rome, and Louisiana State University are described. This experiment was important for several reasons: (1) it was the first coincidence experiment between cryogenic resonant-mass detectors; (2) it improved the observational upper limit on the flux of impulsive gravitational waves that impinge upon the earth; and (3) it lead to the development of a data analysis method for converting the experimental results into an astrophysically meaningful limit on the flux of gravitational radiation from impulsive events. Second, the development of a superconducting thin-film motion transducer intended for use on an ultra-low temperature detector now under construction is described. The sensitivity goal is h = 1 {times} 10{sup {minus}20}. To reach this goal the physical temperature of the detector will be lowered to 40 mK, a lower-noise SQUID amplifier will be used, and a new motion transducer will be developed.

Stevenson, T.R.

1991-01-01

241

Adapting Data Processing To Compare Model and Experiment Accurately: A Discrete Element Model and Magnetic Resonance Measurements of a 3D Cylindrical Fluidized Bed  

PubMed Central

Discrete element modeling is being used increasingly to simulate flow in fluidized beds. These models require complex measurement techniques to provide validation for the approximations inherent in the model. This paper introduces the idea of modeling the experiment to ensure that the validation is accurate. Specifically, a 3D, cylindrical gas-fluidized bed was simulated using a discrete element model (DEM) for particle motion coupled with computational fluid dynamics (CFD) to describe the flow of gas. The results for time-averaged, axial velocity during bubbling fluidization were compared with those from magnetic resonance (MR) experiments made on the bed. The DEM-CFD data were postprocessed with various methods to produce time-averaged velocity maps for comparison with the MR results, including a method which closely matched the pulse sequence and data processing procedure used in the MR experiments. The DEM-CFD results processed with the MR-type time-averaging closely matched experimental MR results, validating the DEM-CFD model. Analysis of different averaging procedures confirmed that MR time-averages of dynamic systems correspond to particle-weighted averaging, rather than frame-weighted averaging, and also demonstrated that the use of Gaussian slices in MR imaging of dynamic systems is valid. PMID:24478537

2013-01-01

242

Microwave measurement test results of circular waveguide components for electron cyclotron resonant heating (ECRH) of the Tandem Mirror Experiment-Upgrade (TMX-U)  

SciTech Connect

Development of high-power components for electron cyclotron resonant heating (ECRH) applications requires extensive testing. In this paper we describe the high-power testing of various circular waveguide components designed for application on the Tandem Mirror Experiment-Upgrade (TMX-U). These include a 2.5-in. vacuum valve, polarizing reflectors, directional couplers, mode converters, and flexible waveguides. All of these components were tested to 200 kW power level with 40-ms pulses. Cold tests were used to determine field distribution. The techniques used in these tests are illustrated. The new high-power test facility at Lawrence Livermore National Laboratory (LLNL) is described and test procedures are discussed. We discuss the following test results: efficiency at high power of mode converters, comparison of high power vs low power for waveguide components, and full power tests of the waveguide system. We also explain the reasons behind selection of these systems for use on TMX-U.

Williams, C.W.; Rubert, R.R.; Coffield, F.E.; Felker, B.; Stallard, B.W.; Taska, J.

1983-12-01

243

Simulation of non-resonant internal kink mode with toroidal rotation in the National Spherical Torus Experiment  

NASA Astrophysics Data System (ADS)

Plasmas in spherical and conventional tokamaks, with weakly reversed shear q profile and minimum q above but close to unity, are susceptible to an non-resonant (m,n) = (1,1) internal kink mode. This mode can saturate and persist and can induce a (2,1) seed island for Neoclassical Tearing Mode. [Breslau et al. Nucl. Fusion 51, 063027 (2011)]. The mode can also lead to large energetic particle transport and significant broadening of beam-driven current. Motivated by these important effects, we have carried out extensive nonlinear simulations of the mode with finite toroidal rotation using parameters and profiles of an NTSX plasma with a weakly reversed shear profile. The numerical results show that, at the experimental level, plasma rotation has little effect on either equilibrium or linear stability. However, rotation can significantly influence the nonlinear dynamics of the (1,1) mode and the induced (2,1) magnetic island. The simulation results show that a rotating helical equilibrium is formed and maintained in the nonlinear phase at finite plasma rotation. In contrast, for non-rotating cases, the nonlinear evolution exhibits dynamic oscillations between a quasi-2D state and a helical state. Furthermore, the effects of rotation are found to greatly suppress the (2,1) magnetic island even at a low level.

Wang, Feng; Fu, G. Y.; Breslau, J. A.; Tritz, Kevin; Liu, J. Y.

2013-07-01

244

Simulation of non-resonant internal kink mode with toroidal rotation in the National Spherical Torus Experiment  

SciTech Connect

Plasmas in spherical and conventional tokamaks, with weakly reversed shear q profile and minimum q above but close to unity, are susceptible to an non-resonant (m,n) = (1,1) internal kink mode. This mode can saturate and persist and can induce a (2,1) seed island for Neoclassical Tearing Mode. [Breslau et al. Nucl. Fusion 51, 063027 (2011)]. The mode can also lead to large energetic particle transport and significant broadening of beam-driven current. Motivated by these important effects, we have carried out extensive nonlinear simulations of the mode with finite toroidal rotation using parameters and profiles of an NTSX plasma with a weakly reversed shear profile. The numerical results show that, at the experimental level, plasma rotation has little effect on either equilibrium or linear stability. However, rotation can significantly influence the nonlinear dynamics of the (1,1) mode and the induced (2,1) magnetic island. The simulation results show that a rotating helical equilibrium is formed and maintained in the nonlinear phase at finite plasma rotation. In contrast, for non-rotating cases, the nonlinear evolution exhibits dynamic oscillations between a quasi-2D state and a helical state. Furthermore, the effects of rotation are found to greatly suppress the (2,1) magnetic island even at a low level.

Wang, Feng; Liu, J. Y. [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)] [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Fu, G. Y.; Breslau, J. A. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)] [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Tritz, Kevin [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States)] [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

2013-07-15

245

Operational experience with the Argonne National Laboratory Californium Rare Ion Breeder Upgrade facility and electron cyclotron resonance charge breedera)  

NASA Astrophysics Data System (ADS)

The Californium Rare Ion Breeder Upgrade (CARIBU) of the Argonne National Laboratory Argonne Tandem Linac Accelerator System (ATLAS) facility provides low-energy and accelerated neutron-rich radioactive beams to address key nuclear physics and astrophysics questions. A 350 mCi 252Cf source produces fission fragments which are thermalized and collected by a helium gas catcher into a low-energy particle beam with a charge of 1+ or 2+. An electron cyclotron resonance (ECR) ion source functions as a charge breeder in order to raise the ion charge sufficiently for acceleration in the ATLAS linac. The ECR charge breeder has achieved stable beam charge breeding efficiencies of 10.1% for 23Na7+, 17.9% for 39K10+, 15.6% for 84Kr17+, and 12.4% for 133Cs27+. For the radioactive beams, a charge breeding efficiency of 11.7% has been achieved for 143Cs27+ and 14.7% for 143Ba27+. The typical breeding times are 10 ms/charge state, but the source can be tuned such that this value increases to 100 ms/charge state with the best breeding efficiency corresponding to the longest breeding times—the variation of efficiencies with breeding time will be discussed. Efforts have been made to characterize and reduce the background contaminants present in the ion beam through judicious choice of q/m combinations. Methods of background reduction are being investigated based upon plasma chamber cleaning and vacuum practices.

Vondrasek, R.; Clark, J.; Levand, A.; Palchan, T.; Pardo, R.; Savard, G.; Scott, R.

2014-02-01

246

Proposed rocket experiments to measure the profile and intensity of the solar He1584A resonance line  

NASA Technical Reports Server (NTRS)

The intensity and profile of the helium resonance line at 584 A from the entire disc of the sun was investigated using a rocket-borne helium-filled spectrometer and a curve of growth technique. The line profile was found to be accurately represented by a Gaussian profile with full width at half maximum of 122 plus or minus 10m A while the integrated intensity was measured to be (2.6 plus or minus 1.3) x 10 to the 9th power/photons sec sq cm at solar levels of F sub 10.7 = 90.8 x 10 to the minus 22th power/sq m H sub z and R sub z = 27. The measured linewidth is in good agreement with previous spectrographic measurement but the integrated intensity is larger than most previous photoelectric measurements. However, the derived line center flux of (2.0 plus or minus 1.0) x 10 to the 10th power/photons sec sq cm A is in good agreement with values inferred from airglow measurements.

Judge, D. L.

1978-01-01

247

Fano resonances in prism-coupled multimode square micropillar resonators.  

PubMed

We report Fano resonances in a multimode square glass micropillar resonator; the resonances were obtained by using angle-resolved prism coupling. Our experiments reveal characteristically asymmetric line shapes of high-Q resonances and of detuned low-Q resonances in multimode reflection spectra. The asymmetric resonance line shapes evolve for an approximately pi phase within a 0.5 degree range of reflection angles. We model our observed asymmetric multimode resonances by the far-field interference between a light wave that is evanescently coupled with a high-Q mode orbit and a coherent light wave that is refractively coupled with a detuned low-Q mode orbit. PMID:16007796

Lee, Ho-Tong; Zhou, Linjie; Poon, Andrew W

2005-06-15

248

The distribution and prognosis of anomalous coronary arteries identified by cardiovascular magnetic resonance: 15 year experience from two tertiary centres  

PubMed Central

Background Aberrant coronary arteries represent a diverse group of congenital disorders. Post-mortem studies reveal a high risk of exercise-related sudden cardiac death in those with an anomalous coronary artery originating from the opposite sinus of Valsalva (ACAOS) with an inter-arterial course. There is little documentation of lifetime history and long-term follow-up of patients with coronary artery anomalies. Methods Patients with anomalous coronary arteries undergoing cardiovascular magnetic resonance over a 15-year period were identified and classified by anatomy and course. Medical records were reviewed for major adverse cardiovascular events (MACE). Revascularisation or myocardial infarction counted only if occurring in the distribution of the anomalous artery. Results Consecutive patients with coronary artery anomalies were retrospectively identified (n?=?172). Median follow-up time was 4.3 years (IQR 2.5–7.8, maximum 15.6). 116 patients had ACAOS of which 64 (55%) had an inter-arterial course (IAC) and 52 (45%) did not. During follow up 110 ACAOS patients were alive, 5 died and 1 lost to follow-up. ACAOS patients experienced 58 MACE events (5 cardiovascular deaths, 5 PCI, 24 CABG and 24 had myocardial infarction). 47 MACE events occurred in ACAOS with IAC and 11 in those without (p?

2014-01-01

249

Operational experience with the Argonne National Laboratory Californium Rare Ion Breeder Upgrade facility and electron cyclotron resonance charge breeder.  

PubMed

The Californium Rare Ion Breeder Upgrade (CARIBU) of the Argonne National Laboratory Argonne Tandem Linac Accelerator System (ATLAS) facility provides low-energy and accelerated neutron-rich radioactive beams to address key nuclear physics and astrophysics questions. A 350 mCi (252)Cf source produces fission fragments which are thermalized and collected by a helium gas catcher into a low-energy particle beam with a charge of 1+ or 2+. An electron cyclotron resonance (ECR) ion source functions as a charge breeder in order to raise the ion charge sufficiently for acceleration in the ATLAS linac. The ECR charge breeder has achieved stable beam charge breeding efficiencies of 10.1% for (23)Na(7+), 17.9% for (39)K(10+), 15.6% for (84)Kr(17+), and 12.4% for (133)Cs(27+). For the radioactive beams, a charge breeding efficiency of 11.7% has been achieved for (143)Cs(27+) and 14.7% for (143)Ba(27+). The typical breeding times are 10 ms/charge state, but the source can be tuned such that this value increases to 100 ms/charge state with the best breeding efficiency corresponding to the longest breeding times-the variation of efficiencies with breeding time will be discussed. Efforts have been made to characterize and reduce the background contaminants present in the ion beam through judicious choice of q/m combinations. Methods of background reduction are being investigated based upon plasma chamber cleaning and vacuum practices. PMID:24593608

Vondrasek, R; Clark, J; Levand, A; Palchan, T; Pardo, R; Savard, G; Scott, R

2014-02-01

250

Hyperemic stress myocardial perfusion cardiovascular magnetic resonance in mice at 3 Tesla: initial experience and validation against microspheres  

PubMed Central

Background Dynamic first pass contrast-enhanced myocardial perfusion is the standard CMR method for the estimation of myocardial blood flow (MBF) and MBF reserve in man, but it is challenging in rodents because of the high temporal and spatial resolution requirements. Hyperemic first pass myocardial perfusion CMR during vasodilator stress in mice has not been reported. Methods Five C57BL/6 J mice were scanned on a clinical 3.0 Tesla Achieva system (Philips Healthcare, Netherlands). Vasodilator stress was induced via a tail vein catheter with an injection of dipyridamole. Dynamic contrast-enhanced perfusion imaging (Gadobutrol 0.1 mmol/kg) was based on a saturation recovery spoiled gradient echo method with 10-fold k-space and time domain undersampling (k-t PCA). One week later the mice underwent repeat anaesthesia and LV injections of fluorescent microspheres at rest and at stress. Microspheres were analysed using confocal microscopy and fluorescence-activated cell sorting. Results Mean MBF at rest measured by Fermi-function constrained deconvolution was 4.1?±?0.5 ml/g/min and increased to 9.6?±?2.5 ml/g/min during dipyridamole stress (P?=?0.005). The myocardial perfusion reserve was 2.4 ±?0.54. The mean count ratio of stress to rest microspheres was 2.4 ±?0.51 using confocal microscopy and 2.6?±?0.46 using fluorescence. There was good agreement between cardiovascular magnetic resonance CMR and microspheres with no significant difference (P?=?0.84). Conclusion First-pass myocardial stress perfusion CMR in a mouse model is feasible at 3 Tesla. Rest and stress MBF values were consistent with existing literature and perfusion reserve correlated closely to microsphere analysis. Data were acquired on a 3 Tesla scanner using an approach similar to clinical acquisition protocols, potentially facilitating translation of imaging findings between rodent and human studies. PMID:23870734

2013-01-01

251

Autoimmune pancreatitis: multidetector-row computed tomography (MDCT) and magnetic resonance (MR) findings in the Italian experience.  

PubMed

Multidetector-row computed tomography (MDCT) and magnetic resonance (MR) imaging are currently the most frequently performed imaging modalities for the study of pancreatic disease. In cases of suspected autoimmune pancreatitis (AIP), a dynamic quadriphasic (precontrast, contrast-enhanced pancreatic, venous and late phases) study is recommended in both techniques. In the diffuse form of autoimmune pancreatitis (DAIP), the pancreatic parenchyma shows diffuse enlargement and appears, during the MDCT and MR contrast-enhanced pancreatic phase, diffusely hypodense and hypointense, respectively, compared to the spleen because of lymphoplasmacytic infiltration and pancreatic fibrosis. During the venous phase of MDCT and MR imaging, the parenchyma appears hyperdense and hyperintense, respectively, in comparison to the pancreatic phase. In the delayed phase of both imaging modalities, it shows retention of contrast media. A "capsule-like rim" may be recognised as a peripancreatic MDCT hyperdense and MR hypointense halo in the T2-weighted images, compared to the parenchyma. DAIP must be differentiated from non-necrotizing acute pancreatitis (NNAP) and lymphoma since both diseases show diffuse enlargement of the pancreatic parenchyma. The differential diagnosis is clinically difficult, and dynamic contrast-enhanced MDCT has an important role. In the focal form of autoimmune pancreatitis (FAIP), the parenchyma shows segmental enlargement involving the head, the body-tail or the tail, with the same contrast pattern as the diffuse form on both modalities. FAIP needs to be differentiated from pancreatic adenocarcinoma to avoid unnecessary surgical procedures, since both diseases have similar clinical and imaging presentation. The differential diagnosis is clinically difficult, and dynamic contrast-enhanced MDCT and MR imaging both have an important role. MR cholangiopancreatography helps in the differential diagnosis. Furthermore, MDCT and MR imaging can identify the extrapancreatic manifestations of AIP, most commonly biliary, renal and retroperitoneal. Finally, in all cases of uncertain diagnosis, MDCT and/or MR follow-up after short-term treatment (2-3 weeks) with high-dose steroids can identify a significant reduction in size of the pancreatic parenchyma and, in FAIP, normalisation of the calibre of the upstream main pancreatic duct. PMID:24638911

Graziani, Rossella; Mautone, Simona; Ambrosetti, Maria Chiara; Manfredi, Riccardo; Re, Thomas J; Calculli, Lucia; Frulloni, Luca; Pozzi Mucelli, Roberto

2014-08-01

252

Signature of the seasonal migration of global lightning in the variation of Schumann resonance peak frequencies - Theory versus experiment  

NASA Astrophysics Data System (ADS)

The distance between the active lightning sources and a fixed receiver changes when the global lightning migrates northward/southward over the year. Schumann resonance (SR) peak frequencies depend on both the source-observer geometry and the propagation conditions in the Earth-ionosphere cavity. The source-observer geometry can be manifest in frequency variations with different signs for the different modes and field components. This distance- dependent frequency variation is demonstrated in SR frequency observations at Nagycenk, Hungary. The position of the lightning centroids is documented with respect to the observer in the longitudinal range of the three tropical chimney regions for each month on the basis of the OTD/LIS satellite observations. Simulation of the distance-dependent frequency variation is based on the computation of the spectra of the vertical electric, north-south, and east-west magnetic field components, via the Two-Dimensional Telegraph Equation (TDTE) technique (Kirillov, 2002) for each chimney region in its diurnal phase of greatest activity, and with each (Maritime Continent, Africa, America) having well established spatial-temporal dynamics. Modal peak frequencies are being obtained, along with modal intensities and quality factors, by means of the least-squares fitting of "experimental" spectra by the "classic" Lorentzian functional (Williams et al., 2006). For each chimney region, numerous scenarios have been simulated; to consider the first and second Lorentzian-modes, a five-mode (N=5) Lorentzian procedure has been exploited. The largest frequency response (maximum in Northern hemisphere summer, minimum in winter) for the seasonal migration can be observed in the case of the 1st Ez mode when it is dominated by the Maritime Continent (7-10 UT). According to the simulation, this maximal response is attributed to the source proximity to the nodal region at about 10 Mm distance, where the frequency exhibits singular behavior. In the case of Africa, the frequency varies little during the seasonal migration and has opposite sign: lower in Northern Hemisphere summer than winter. The frequency has only minor fluctuation in the case of the American source due to the seasonal migration path being roughly perpendicular to the source-receiver great circle. The 1st magnetic mode has increasing frequency at Nagycenk with increasing source distance in accordance with the theoretical description. These general methods are suitable to identify global redistribution of global lightning due to climate change.

Sátori, Gabriella; Mushtak, Vadim; Williams, Earle; Nagy, Tamás.

2010-05-01

253

A search for a heavy resonance decaying to a top quark and bottom quark with the CMS experiment  

NASA Astrophysics Data System (ADS)

The standard model of particle physics can explain most measurements of elementary particle properties and interactions performed to date. However, it does not naturally explain the relatively light Higgs boson mass or the existence of small neutrino masses, and has no explanation for the dark matter observed in the universe. Many extensions to the standard model have been proposed to attempt to address these questions, and several predict the existence of heavy charged gauge bosons, usually referred to as W' bosons. The Large Hadron Collider at CERN is the largest and most powerful particle accelerator in the world and offers the opportunity to search for W' bosons using the CMS experiment, a large multi-purpose particle detector. Results are presented from a search for a W' boson produced in proton-proton collisions at a center of mass energy sqrt(s)=8 TeV and decaying into a top and a bottom quark, using a dataset collected by the CMS experiment corresponding to an integrated luminosity of 19.5 fb-1. Various models of W' boson production are studied by allowing for an arbitrary combination of left- and right-handed fermionic couplings. The analysis is based on the detection of events with an electron or muon, jets and missing transverse energy in the final state. No evidence for W' boson production is found and 95% confidence level upper limits are obtained on the production cross section for several mass hypotheses and compared to theoretical predictions. For W' bosons with purely right-handed couplings, and for those with left-handed couplings when ignoring interference effects, the observed 95% confidence level limit on the W' boson mass is M(W')>2.05 TeV. These are the most stringent limits obtained to date in this channel.

Sperka, David M.

254

NMR and NQR studies of the heavy fermion superconductors CeTIn5 (T=Co and Ir)  

Microsoft Academic Search

We have carried out 115In and 59Co nuclear quadrupole resonance and nuclear magnetic resonance measurements on CeCoIn5 and CeIrIn5. The temperature T dependence of the nuclear spin-lattice relaxation rate 1\\/T1 of 115In in the normal state indicates that CeCoIn5 is located just at an antiferromagnetic instability, and CeIrIn5 is in the nearly antiferromagnetic region. In the superconducting state, 1\\/T1 has

Y. Kohori; Y. Yamato; Y. Iwamoto; T. Kohara; E. D. Bauer; M. B. Maple; J. L. Sarrao

2001-01-01

255

An instrument for fast acquisition of fluorescence decay curves at picosecond resolution designed for ``double kinetics'' experiments: Application to fluorescence resonance excitation energy transfer study of protein folding  

NASA Astrophysics Data System (ADS)

The information obtained by studying fluorescence decay of labeled biopolymers is a major resource for understanding the dynamics of their conformations and interactions. The lifetime of the excited states of probes attached to macromolecules is in the nanosecond time regime, and hence, a series of snapshot decay curves of such probes might - in principle - yield details of fast changes of ensembles of labeled molecules down to sub-microsecond time resolution. Hence, a major current challenge is the development of instruments for the low noise detection of fluorescence decay curves within the shortest possible time intervals. Here, we report the development of an instrument, picosecond double kinetics apparatus, that enables recording of multiple fluorescence decay curves with picosecond excitation pulses over wide spectral range during microsecond data collection for each curve. The design is based on recording and averaging multiphoton pulses of fluorescence decay using a fast 13 GHz oscilloscope during microsecond time intervals at selected time points over the course of a chemical reaction or conformational transition. We tested this instrument in a double kinetics experiment using reference probes (N-acetyl-tryptophanamide). Very low stochastic noise level was attained, and reliable multi-parameter analysis such as derivation of distance distributions from time resolved FRET (fluorescence resonance excitation energy transfer) measurements was achieved. The advantage of the pulse recording and averaging approach used here relative to double kinetics methods based on the established time correlated single photon counting method, is that in the pulse recording approach, averaging of substantially fewer kinetic experiments is sufficient for obtaining the data. This results in a major reduction in the consumption of labeled samples, which in many cases, enables the performance of important experiments that were not previously feasible.

Ishay, Eldad Ben; Hazan, Gershon; Rahamim, Gil; Amir, Dan; Haas, Elisha

2012-08-01

256

New aspects on URu2Si2 and CeT In5 (T=Rh, Ir, Co) observed by high pressure NMR and NQR  

NASA Astrophysics Data System (ADS)

NMR and NQR studies on two interesting systems (URu2Si2, CeTIn5) were performed under high pressure. (1) URu2Si2: In the pressure range 3.0 to 8.3 kbar, we have observed new 29Si NMR signals arising from the antiferromagnetic (AF) region besides the previously observed 29Si NMR signals which come from the paramagnetic (PM) region in the sample. This gives definite evidence for spatially-inhomogeneous development of AF ordering below T0 of 17.5 K. The volume fraction is enhanced by applied pressure, whereas the value of internal field (~ 91 mT) remains constant up to 8.3 kbar. In the AF region, the ordered moment is about one order of magnitude larger than 0.03 mB. (2) CeTIn5: The pressure and temperature (T) dependences of nuclear spin-lattice relaxation rate 1/T1 of 115In in CeTIn5 have shown that the superconductivity (SC) occurs close to an AF instability. From the T dependences of 1/T1and Knight shift below Tc, CeTIn5 has been found to exhibit non-s wave (probable d wave) SC with even parity and line nodes in the SC energy gap.

Kohara, T.

2002-05-01

257

Hybridization-driven gap in U3Bi4Ni3: a 209Bi NMR/NQR study  

SciTech Connect

We report {sup 209}Bi nuclear-magnetic-resonance and nuclear-quadrupole-resonance measurements on a single crystal of the Kondo insulator U{sub 3}Bi{sub 4}Ni{sub 3}. The {sup 209}Bi nuclear-spin-lattice relaxation rate (T{sub 1}{sup -1}) shows activated behavior and is well fit by a spin gap of 220 K. The {sup 209}Bi Knight shift (K) exhibits a strong temperature dependence arising from 5f electrons, in which K is negative at high temperatures and increases as the temperature is lowered. Below 50 K, K shows a broad maximum and decreases slightly upon further cooling. Our data provide insight into the evolution of the hyperfine fields in a fully gapped Kondo insulator based on 5f electron hybridization.

Baek, Seung H [Los Alamos National Laboratory

2009-01-01

258

Early experience with multiparametric magnetic resonance imaging-targeted biopsies under visual transrectal ultrasound guidance in patients suspicious for prostate cancer undergoing repeated biopsy.  

PubMed

Abstract Objectives. The purpose of this study was to investigate the detection rate of prostate cancer (PCa) by multiparametric magnetic resonance imaging-targeted biopsies (mp-MRI-bx) in patients with prior negative transrectal ultrasound biopsy (TRUS-bx) sessions without previous experience of this. Material and methods. Eighty-three patients with prior negative TRUS-bx scheduled for repeated biopsies due to persistent suspicion of PCa were prospectively enrolled. mp-MRI was performed before biopsy and all lesions were scored according to the Prostate Imaging Reporting and Data System (PI-RADS) and Likert classification. All underwent repeated TRUS-bx (10 cores) and mp-MRI-bx under visual TRUS guidance of any mp-MRI-suspicious lesion not targeted by systematic TRUS-bx. Results.PCa was found in 39 out of 83 patients (47%) and mp-MRI identified at least one lesion with some degree of suspicion in all 39 patients. Both PI-RADS and Likert scoring showed a high correlation between suspicion of malignancy and biopsy results (p < 0.0001). Five patients (13%) had cancer detected only on mp-MRI-bx outside the TRUS-bx areas (p = 0.025) and another seven patients (21%) had an overall Gleason score upgrade of at least one grade based on the mp-MRI-bx. Secondary PCa lesions not visible on mp-MRI were detected by TRUS-bx in six out of 39 PCa patients. The secondary foci were all Gleason 6 (3 + 3) in 5-10% of the biopsy core. According to the Epstein criteria, 37 out of 39 cancer patients were classified as clinically significant. Conclusion. Using mp-MRI, even without previous experience, can improve the detection rate of significant PCa at repeated biopsy and allows more accurate Gleason grading. PMID:24922550

Boesen, Lars; Noergaard, Nis; Chabanova, Elizaveta; Logager, Vibeke; Balslev, Ingegerd; Mikines, Kari; Thomsen, Henrik S

2015-02-01

259

Development of a compact fast CCD camera and resonant soft x-ray scattering endstation for time-resolved pump-probe experiments.  

PubMed

The designs of a compact, fast CCD (cFCCD) camera, together with a resonant soft x-ray scattering endstation, are presented. The cFCCD camera consists of a highly parallel, custom, thick, high-resistivity CCD, readout by a custom 16-channel application specific integrated circuit to reach the maximum readout rate of 200 frames per second. The camera is mounted on a virtual-axis flip stage inside the RSXS chamber. When this flip stage is coupled to a differentially pumped rotary seal, the detector assembly can rotate about 100°/360° in the vertical/horizontal scattering planes. With a six-degrees-of-freedom cryogenic sample goniometer, this endstation has the capability to detect the superlattice reflections from the electronic orderings showing up in the lower hemisphere. The complete system has been tested at the Advanced Light Source, Lawrence Berkeley National Laboratory, and has been used in multiple experiments at the Linac Coherent Light Source, SLAC National Accelerator Laboratory. PMID:21806178

Doering, D; Chuang, Y-D; Andresen, N; Chow, K; Contarato, D; Cummings, C; Domning, E; Joseph, J; Pepper, J S; Smith, B; Zizka, G; Ford, C; Lee, W S; Weaver, M; Patthey, L; Weizeorick, J; Hussain, Z; Denes, P

2011-07-01

260

Multiband Superconductivity in Filled-Skutterudite Compounds (Pr1-xLax)Os4Sb12: An Sb Nuclear-Quadrupole-Resonance Study  

NASA Astrophysics Data System (ADS)

We report on the systematic evolution of normal-state properties and superconducting characteristics in filled-skutterudite compounds (Pr1-xLax)Os4Sb12 determined using Sb nuclear-quadrupole-resonance (NQR) experiments. The Sb-NQR spectra in these compounds have split into two sets, arising from different Sb12 cages containing either Pr or La, which enables us to measure two kinds of nuclear spin-lattice relaxation time T1Pr and T1La. In the normal state, the temperature (T) dependence of 1/T1PrT showed almost the same behavior as that for pure PrOs4Sb12 regardless of the increase in La content. In contrast, 1/T1LaT markedly decreases with increasing La concentration. These results show that 4 f2-derived magnetic fluctuations are almost localized at the Pr site. In the superconducting state for Pr-rich compounds of x=0.05 and 0.2, 1/T1Pr exponentially decreases down to T=0.7 K with no coherence peak below Tc as well as in PrOs4Sb12. A remarkable finding is that the residual density of states (RDOS) at the Fermi level below Tc is induced by La substitution for Pr. The impurity effect, usually observed in unconventional superconductors with a line-node gap, may not be the origin of the RDOS induced by the La substitution, since RDOS does not increase and Tc does not decrease with increasing La content. RDOS is more naturally explained if a small part (˜5.5%) of the total Fermi surface (FS) becomes gapless for x=0.05 and 0.2. These results are proposed to be understood in terms of a multiband-superconductivity (MBSC) model that assumes a full gap for part of the FS and the presence of point nodes for a small 4 f2-derived FS inherent in PrOs4Sb12. The former could be relevant with FS existing in LaOs4Sb12 and with the anisotropic gap with point nodes being markedly suppressed by either applying a magnetic field or substituting La for Pr. For La-rich compounds of x=0.8 and 1, on the other hand, 1/T1La exhibits a coherence peak and the nodeless energy gap characteristic for weak-coupling BCS s-wave superconductors. With increasing Pr content, Tc increases and the energy gap increases from 2?0/kBTc=3.45 for pure La compounds up to 2?0/kBTc=4.2 and 5.2 for the 60% Pr and 80% Pr compounds, respectively. The Pr substitution for La enhances the pairing interaction and induces an anisotropy in the energy-gap structure. The novel strong-coupling superconductivity in PrOs4Sb12 is inferred to be mediated by the local interaction between 4 f2-derived crystal-electric-field states with the electric quadrupole degree of freedom and conduction electrons. This coupling causes a mass enhancement of quasi-particles for a part of FS and induces a small FS, which is responsible for point nodes in the superconducting gap function. Note that the small FS does not play any primary role for the strong-coupling superconductivity in PrOs4Sb12.

Yogi, Mamoru; Nagai, Takayuki; Imamura, Yojyu; Mukuda, Hidekazu; Kitaoka, Yoshio; Kikuchi, Daisuke; Sugawara, Hitoshi; Aoki, Yuji; Sato, Hideyuki; Harima, Hisatomo

2006-12-01

261

Effect of a weak static magnetic field on nitrogen-14 quadrupole resonance in the case of an axially symmetric electric field gradient tensor.  

PubMed

The application of a weak static B0 magnetic field (less than 1 mT) may produce a well-defined splitting of the (14)N Quadrupole Resonance line when the electric field gradient tensor at the nitrogen nucleus level is of axial symmetry. It is theoretically shown and experimentally confirmed that the actual splitting (when it exists) as well as the line-shape and the signal intensity depends on three factors: (i) the amplitude of B0, (ii) the amplitude and pulse duration of the radio-frequency field, B1, used for detecting the NQR signal, and (iii) the relative orientation of B0 and B1. For instance, when B0 is parallel to B1 and regardless of the B0 value, the signal intensity is three times larger than when B0 is perpendicular to B1. This point is of some importance in practice since NQR measurements are almost always performed in the earth field. Moreover, in the course of this study, it has been recognized that important pieces of information regarding line-shape are contained in data points at the beginning of the free induction decay (fid) which, in practice, are eliminated for avoiding spurious signals due to probe ringing. It has been found that these data points can generally be retrieved by linear prediction (LP) procedures. As a further LP benefit, the signal intensity loss (by about a factor of three) is regained. PMID:24183810

Guendouz, Laouès; Aissani, Sarra; Marêché, Jean-François; Retournard, Alain; Marande, Pierre-Louis; Canet, Daniel

2013-01-01

262

Atomic resonance and scattering  

SciTech Connect

Experiments were conducted in the following areas: mapping of energy levels of a Rydberg lithium atom in a strong magnetic field in the vicinity of a crossing between levels from different principle quantum numbers, electrodynamics in a cavity, resonance enhanced multiphoton ionization, velocity dependence of rotational rainbow structure in Na2-Ar, high precision mass measurement on single ions using cyclotron resonance, low temperature energy transfer, trapping of neutral atoms, and vibrationally inelastic collisions.

Kleppner, D.; Pritchard, D.E.; Ahmad-Bitar, R.; Ducas, T.; Kelleher, D.; Ligare, M.; Lyyra, A.M.; Moskowitz, P.; Saenger, K.L.; Smith, N.

1984-01-01

263

Feshbach resonances in ultracold gases  

SciTech Connect

Feshbach resonances are the essential tool to control the interaction between atoms in ultracold quantum gases. They have found numerous experimental applications, opening up the way to important breakthroughs. This review broadly covers the phenomenon of Feshbach resonances in ultracold gases and their main applications. This includes the theoretical background and models for the description of Feshbach resonances, the experimental methods to find and characterize the resonances, a discussion of the main properties of resonances in various atomic species and mixed atomic species systems, and an overview of key experiments with atomic Bose-Einstein condensates, degenerate Fermi gases, and ultracold molecules.

Chin Cheng; Grimm, Rudolf; Julienne, Paul; Tiesinga, Eite [Department of Physics and James Franck Institute, University of Chicago, Chicago, Illinois 60637 (United States); Center for Quantum Physics and Institute of Experimental Physics, University of Innsbruck, Technikerstrasse 25, 6020 Innsbruck (Austria) and Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Otto-Hittmair-Platz 1, 6020 Innsbruck (Austria); Joint Quantum Institute, National Institute of Standards and Technology and University of Maryland, 100 Bureau Drive, Gaithersburg, Maryland 20899-8423 (United States)

2010-04-15

264

Institutional Experience With Solid Pseudopapillary Neoplasms: Focus on Computed Tomography, Magnetic Resonance Imaging, Conventional Ultrasound, Endoscopic Ultrasound, and Predictors of Aggressive Histology  

PubMed Central

Objective Solid pseudopapillary neoplasms (SPNs) are low-grade malignancies with an excellent prognosis, albeit with the potential for metastatic disease. This study details our institution's experience with the diagnosis and treatment of SPN, including clinical presentation, multimodality imaging findings, and potential predictors of aggressive tumor behavior. Materials and Methods The institutional pathology database was searched through for all cases of SPN since 1988, yielding 51 patients. The electronic medical record was searched for clinical and demographic information regarding these patients, including age, sex, presenting symptoms, type of surgery, postoperative length of stay, tumor markers, and postsurgical follow-up. All available imaging data were reviewed, including those of 30 patients who underwent multidetector computed tomography, those of 9 patients who underwent magnetic resonance imaging (MRI), those of 3 patients who underwent conventional ultrasound, and those of 11 patients who underwent endoscopic ultrasound. Results A total of 84% of patients were females, with a mean age of only 33 years. Prognosis was excellent, with a mean follow-up of 3 years without recurrence. Only 1 of the 51 patients developed metastatic disease to the liver 8 years after the surgery. On computed tomography, lesions tended to be large (5.3 cm), well circumscribed (29/30), round/oval (20/30), and encapsulated (23/30). The lesions often demonstrated calcification (14/30) and typically resulted in no biliary or pancreatic ductal dilatation. The lesions ranged from completely cystic to completely solid. On MRI, the lesions often demonstrated a T2 hypointense or enhancing capsule (6/9) and demonstrated internal blood products (5/9). The lesions tended to be devoid of vascularity on conventional ultrasound. Ten patients were found to have “aggressive” histology at presentation (T3 tumor, nodal involvement, perineural invasion, or vascular invasion). No demographic, clinical, or multidetector computed tomographic imaging features were found to correlate with aggressive histology. Conclusions Certain imaging features (eg, well-circumscribed mass with calcification, peripheral capsule, internal blood products, and lack of biliary/pancreatic ductal obstruction) on computed tomography and MRI are highly suggestive of the diagnosis of SPN, particularly when visualized in young female patients. However, it is not possible to predict aggressive histology on the basis of imaging findings, clinical presentation, or patient demographic features. PMID:24045264

Raman, Siva P.; Kawamoto, Satomi; Law, Joanna K.; Blackford, Amanda; Lennon, Anne Marie; Wolfgang, Christopher L.; Hruban, Ralph H.; Cameron, John L.; Fishman, Elliot K.

2014-01-01

265

Nuclear quadrupole resonance studies of transparent conducting oxides.  

PubMed

We report (63,65)Cu spin-lattice relaxation rates measured by nuclear quadrupole resonance (NQR) in the delafossite compound CuYO(2) and CuYO(2):Ca over a temperature range from 200 to 450K. CuYO(2):Ca is a prototype transparent oxide exhibiting p-type electrical conductivity. Relaxation rates in CuYO(2):Ca are enhanced by one to two orders of magnitude relative to undoped material, exhibit much stronger temperature dependence, and contain contributions from magnetic and quadrupolar relaxation mechanisms with roughly equal strengths. Relaxation in undoped CuYO(2) is of purely quadrupolar origin and is attributed to interactions with lattice phonons. The main focus of this paper is the magnetic contribution to the relaxation rate in CuYO(2):Ca which is attributed to the hyperfine fields of carriers. It is argued that the dynamics of the hyperfine field are dominated by the hopping rate for carrier transfers between neighboring atoms in the copper planes of the delafossite structure. Comparison of the magnetic relaxation rates with the DC conductivity permits an estimate of the carrier concentration and mobility. PMID:15388186

Warren, W W; Rajabzadeh, A; Olheiser, T; Liu, J; Tate, J; Jayaraj, M K; Vanaja, K A

2004-01-01

266

Microwave permittivity and permeability experiments in high-loss dielectrics: Caution with implicit Fabry-Pérot resonance for negative imaginary permeability  

NASA Astrophysics Data System (ADS)

Various materials have been examined to obtain permittivity and permeability values required for detailed investigations on functional materials like microwave-absorbing and high-permittivity dielectrics. We call for caution when samples exhibit negative imaginary permeability, whether containing a resonance peak or not. In the retrieval procedure, the Fabry-Pérot resonance (FPR) can produce a negative imaginary permeability, which should be classified as an extrinsic rather than an intrinsic physical attribute. In particular, for high-loss materials, the implicit FPR would bring a plausible negative imaginary permeability. Here we have listed a dielectric dispersion of FPR behavior for BiFeO3 samples.

Hou, Zhi-Ling; Zhang, Min; Kong, Ling-Bao; Fang, Hui-Min; Li, Zhong-Jun; Zhou, Hai-Feng; Jin, Hai-Bo; Cao, Mao-Sheng

2013-10-01

267

Optical resonator  

NASA Technical Reports Server (NTRS)

The invention discloses a semi-ring Fabry-Perot (SRFP) optical resonator structure comprising a medium including an edge forming a reflective facet and a waveguide within the medium, the waveguide having opposing ends formed by the reflective facet. The performance of the SRFP resonator can be further enhanced by including a Mach-Zehnder interferometer in the waveguide on one side of the gain medium. The optical resonator can be employed in a variety of optical devices. Laser structures using at least one SRFP resonator are disclosed where the resonators are disposed on opposite sides of a gain medium. Other laser structures employing one or more resonators on one side of a gain region are also disclosed.

Taghavi-Larigani, Shervin (Inventor); Vanzyl, Jakob J. (Inventor); Yariv, Amnon (Inventor)

2006-01-01

268

NUCLEAR SPIN RESONANCE  

Microsoft Academic Search

The first experiments on nuclear quadrupole interactions in crystals ; were carried out by R. V. Pound (Phys. Rev., magnetic resonance lines and by H. ; G. Dehmelt and H. Kruger (Naturwiss., 37: 111(1950)) who observed the absorption ; of radiowaves in a neutral magnetic field. The work was subsequently continued ; in two directions: toward the study of large,

V. S. Grechishkin; N. E. Ainbinder

1963-01-01

269

Magnetic Criticality and Unconventional Superconductivity in CeCoIn5: Study of 115In-Nuclear Quadrupole Resonance under Pressure  

NASA Astrophysics Data System (ADS)

We report the systematic evolution of the superconducting (SC) characteristics of the heavy-fermion (HF) superconductor CeCoIn5 via nuclear-quadrupole-resonance (NQR) measurement under pressure (P). The application of P significantly suppresses the nuclear spin-lattice relaxation rate 1/T1 that is dominated by antiferromagnetic (AFM) spin fluctuations (SFs) specific to a quantum critical point (QCP). It is demonstrated that the marked suppression of AFM SFs leads to a reduction in the SC energy gap or in the coupling strength of the Cooper pair. Tc, nevertheless, increases with increasing P due to the increase in HF bandwidth. This is expected to make the lifetime of quasi-particles sufficiently long.

Yashima, M.; Kawasaki, S.; Kawasaki, Y.; Zheng, G.-q.; Kitaoka, Y.; Shishido, H.; Settai, R.; Haga, Y.; ?nuki, Y.

2004-08-01

270

Local magnetic and structural properties of the low-temperature orthorhombic to low-temperature tetragonal transition: A {sup 139}La NQR study in lightly hole-doped La{sub 1.8{minus}x}Eu{sub 0.2}Sr{sub x}CuO{sub 4}  

SciTech Connect

{sup 139}La nuclear quadrupole resistance (NQR) and relaxation measurements in lightly hole-doped La{sub 1.8{minus}x}Eu{sub 0.2}Sr{sub x}CuO{sub 4} have been used to investigate the microscopic properties of the low-temperature orthorhombic to low-temperature tetragonal transition. The transition is characterized by a sharp peak in {sup 139}La NQR relaxation rate, indicating phonon softening. We find that the structural phase transition is accompanied by a modification of the spin state. The data for the spin freezing and the recovery of sublattice magnetization at low T are presented and discussed in relation to the studies of La{sub 2{minus}x}Sr{sub x}CuO{sub 4} and La{sub 2}Cu{sub 1{minus}x}Li{sub x}O{sub 4}. {copyright} {ital 1999} {ital The American Physical Society}

Suh, B.J.; Hammel, P.C. [Condensed Matter and Thermal Physics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Condensed Matter and Thermal Physics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Huecker, M.; Buechner, B. [II. Physikalisches Institut, Universitaet zu Koeln, D-50937 Koeln (Germany)] [II. Physikalisches Institut, Universitaet zu Koeln, D-50937 Koeln (Germany)

1999-02-01

271

Local magnetic and structural properties of the low-temperature orthorhombic to low-temperature tetragonal transition: A 139La NQR study in lightly hole-doped La1.8-xEu0.2SrxCuO4  

NASA Astrophysics Data System (ADS)

139La nuclear quadrupole resistance (NQR) and relaxation measurements in lightly hole-doped La1.8-xEu0.2SrxCuO4 have been used to investigate the microscopic properties of the low-temperature orthorhombic to low-temperature tetragonal transition. The transition is characterized by a sharp peak in 139La NQR relaxation rate, indicating phonon softening. We find that the structural phase transition is accompanied by a modification of the spin state. The data for the spin freezing and the recovery of sublattice magnetization at low T are presented and discussed in relation to the studies of La2-xSrxCuO4 and La2Cu1-xLixO4.

Suh, B. J.; Hammel, P. C.; Hücker, M.; Büchner, B.

1999-02-01

272

Zero field NMR and NQR  

Microsoft Academic Search

Methods are described and demonstrated for detecting the coherent evolution of nuclear spin observables in zero magnetic field with the full sensitivity of high field NMR. The principle motivation is to provide a means of obtaining solid state spectra of the magnetic dipole and electric quadrupole interactions of disordered systems without the line broadening associated with random orientation with respect

D. B. Zax; A. Bielecki; K. W. Zilm; A. Pines; D. P. Weitekamp

1985-01-01

273

Closed solution to the Baker-Campbell-Hausdorff problem: exact effective Hamiltonian theory for analysis of nuclear-magnetic-resonance experiments.  

PubMed

A closed solution to the Baker-Campbell-Hausdorff problem is described. The solution, which is based on the Cayley-Hamilton theorem, allows the entanglement between exponential operators to be described by an exact finite series expansion. Addressing specifically the special unitary Lie groups SU(2), SU(3), and SU(4), we derive expansion formulas for the entangled exponential operator as well as for the effective Hamiltonian describing the net evolution of the quantum system. The capability of our so-called exact effective Hamiltonian theory for analytical and numerical analysis is demonstrated by evaluation of multiple-pulse methods within liquid- and solid-state nuclear-magnetic-resonance spectroscopy. The examples include composite pulses for inversion, decoupling, and dipolar recoupling, as well as coherence-order- and spin-state-selective double- to single-quantum conversion, homonuclear dipolar decoupling, finite rf excitation for quadrupolar nuclei, heteronuclear coherence transfer, and gates for quantum computation. PMID:11863504

Untidt, Thomas S; Nielsen, Niels Chr

2002-02-01

274

An improved design method of LLC resonant converter  

Microsoft Academic Search

For LLC resonant converter, design of the resonant tank influences much of the performance. In traditional design ideas, the transformer magnetizing inductance values are more dependent on engineering experience. In this paper, a model is constructed based on the proposed “current angle” theory by accurately calculating the LLC resonant converter in resonant frequency, and an improved design method of LLC

Xue Zhang; Wei You; Wei Yao; Shen Chen; Zhengyu Lu

2012-01-01

275

Sensitivity and spatial resolution for electron-spin-resonance detection by magnetic resonance force microscopy  

E-print Network

The signal intensity of electron spin resonance in magnetic resonance force microscopy MRFM experiments that magnetic resonance force microscopy MRFM is a new 3D imaging technique8,9 with the potential of achieving force microscopy Z. Zhanga) Condensed Matter and Thermal Physics Group, Materials Science and Technology

Hammel, P. Chris

276

Prostate Postbrachytherapy Seed Distribution: Comparison of High-Resolution, Contrast-Enhanced, T1- and T2-Weighted Endorectal Magnetic Resonance Imaging Versus Computed Tomography: Initial Experience  

SciTech Connect

Purpose: To compare contrast-enhanced, T1-weighted, three-dimensional magnetic resonance imaging (CEMR) and T2-weighted magnetic resonance imaging (T2MR) with computed tomography (CT) for prostate brachytherapy seed location for dosimetric calculations. Methods and Materials: Postbrachytherapy prostate MRI was performed on a 1.5 Tesla unit with combined surface and endorectal coils in 13 patients. Both CEMR and T2MR used a section thickness of 3 mm. Spiral CT used a section thickness of 5 mm with a pitch factor of 1.5. All images were obtained in the transverse plane. Two readers using CT and MR imaging assessed brachytherapy seed distribution independently. The dependency of data read by both readers for a specific subject was assessed with a linear mixed effects model. Results: The mean percentage ({+-} standard deviation) values of the readers for seed detection and location are presented. Of 1205 implanted seeds, CEMR, T2MR, and CT detected 91.5% {+-} 4.8%, 78.5% {+-} 8.5%, and 96.1% {+-} 2.3%, respectively, with 11.8% {+-} 4.5%, 8.5% {+-} 3.5%, 1.9% {+-} 1.0% extracapsular, respectively. Assignment to periprostatic structures was not possible with CT. Periprostatic seed assignments for CEMR and T2MR, respectively, were as follows: neurovascular bundle, 3.5% {+-} 1.6% and 2.1% {+-} 0.9%; seminal vesicles, 0.9% {+-} 1.8% and 0.3% {+-} 0.7%; periurethral, 7.1% {+-} 3.3% and 5.8% {+-} 2.9%; penile bulb, 0.6% {+-} 0.8% and 0.3% {+-} 0.6%; Denonvillier's Fascia/rectal wall, 0.5% {+-} 0.6% and 0%; and urinary bladder, 0.1% {+-} 0.3% and 0%. Data dependency analysis showed statistical significance for the type of imaging but not for reader identification. Conclusion: Both enumeration and localization of implanted seeds are readily accomplished with CEMR. Calculations with MRI dosimetry do not require CT data. Dose determinations to specific extracapsular sites can be obtained with MRI but not with CT.

Bloch, B. Nicolas [Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA (United States); Department of Radiology, General Hospital Vienna, Medical University Vienna, Vienna (Austria)], E-mail: nbloch@bidmc.harvard.edu; Lenkinski, Robert E. [Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA (United States); Helbich, Thomas H. [Department of Radiology, General Hospital Vienna, Medical University Vienna, Vienna (Austria); Ngo, Long [Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA (United States); Oismueller, Renee [Institute for Radio-Oncology, Danube Hospital, Vienna (Austria); Jaromi, Silvia; Kubin, Klaus [Department of Radiology, General Hospital Vienna, Medical University Vienna, Vienna (Austria); Hawliczek, Robert [Institute for Radio-Oncology, Danube Hospital, Vienna (Austria); Kaplan, Irving D. [Department of Radiation Oncology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA (United States); Rofsky, Neil M. [Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA (United States)

2007-09-01

277

Improving the sensitivity of a high-Tc SQUID at MHz frequency using a normal metal transformer  

Microsoft Academic Search

Superconducting quantum interference devices (SQUIDs) can be used to detect the signals of nuclear quadrupole resonance (NQR). The NQR frequencies of some interesting materials are in the order of MHz. However, the sensitivity of a high-Tc SQUID is normally not enough to detect the weak NQR signals. To improve the sensitivity of a high-Tc SQUID at MHz frequency, we used

D. F. He; H. Itozaki; M. Tachiki

2006-01-01

278

Systematic 12- and 13-core transrectal ultrasound- or magnetic resonance imaging-guided biopsies significantly improve prostate cancer detection rate: A single-center 13-year experience.  

PubMed

The aim of the present study was to evaluate the value of systematic 12- and 13-core biopsies, guided by transrectal ultrasound (TRUS) or magnetic resonance imaging (MRI), with regard to the prostate cancer detection rate (PCDR). Between July 1999 and June 2012, 2,707 patients were recruited to the Department of Urology, The First Affiliated Hospital of Nanjing Medical University (Nanjing, China). Prostate biopsies were performed via systematic 12- or 13-core biopsy and guided by either TRUS or MRI. The PCDR was established by retrospectively analyzing the distribution of positive cores, and it was assumed that all patients had undergone four biopsy schemes: Medial 6-core, lateral 6-core, 12-core and entire 13-core. In addition, the positive rate of the biopsies with the extra 13th core and the mean positive rate of systematic 12-core biopsies were compared. The PCDR of an entire 13-core biopsy was significantly higher than that of a lateral 6-core biopsy. The positive rate of the extra 13th core, which identified abnormal TRUS or MRI findings, was significantly higher when compared with that of the mean positive rate of the systematic 12-core biopsy. The results of the present study demonstrated that the entire 13-core biopsy was superior to the 6-core biopsy with regard to the PCDR. Therefore, the systematic 12-core biopsy with an extra 13th core is considered to be beneficial towards improving the PCDR. PMID:25202421

Cheng, Gong; Huang, Yuan; Liu, Bianjiang; Zhao, Ruizhe; Shao, Pengfei; Li, Jie; Qin, Chao; Hua, Lixin; Yin, Changjun

2014-10-01

279

Systematic 12- and 13-core transrectal ultrasound- or magnetic resonance imaging-guided biopsies significantly improve prostate cancer detection rate: A single-center 13-year experience  

PubMed Central

The aim of the present study was to evaluate the value of systematic 12- and 13-core biopsies, guided by transrectal ultrasound (TRUS) or magnetic resonance imaging (MRI), with regard to the prostate cancer detection rate (PCDR). Between July 1999 and June 2012, 2,707 patients were recruited to the Department of Urology, The First Affiliated Hospital of Nanjing Medical University (Nanjing, China). Prostate biopsies were performed via systematic 12- or 13-core biopsy and guided by either TRUS or MRI. The PCDR was established by retrospectively analyzing the distribution of positive cores, and it was assumed that all patients had undergone four biopsy schemes: Medial 6-core, lateral 6-core, 12-core and entire 13-core. In addition, the positive rate of the biopsies with the extra 13th core and the mean positive rate of systematic 12-core biopsies were compared. The PCDR of an entire 13-core biopsy was significantly higher than that of a lateral 6-core biopsy. The positive rate of the extra 13th core, which identified abnormal TRUS or MRI findings, was significantly higher when compared with that of the mean positive rate of the systematic 12-core biopsy. The results of the present study demonstrated that the entire 13-core biopsy was superior to the 6-core biopsy with regard to the PCDR. Therefore, the systematic 12-core biopsy with an extra 13th core is considered to be beneficial towards improving the PCDR. PMID:25202421

CHENG, GONG; HUANG, YUAN; LIU, BIANJIANG; ZHAO, RUIZHE; SHAO, PENGFEI; LI, JIE; QIN, CHAO; HUA, LIXIN; YIN, CHANGJUN

2014-01-01

280

Design and testing of a low impedance transceiver circuit for nitrogen-14 nuclear quadrupole resonance.  

PubMed

A low impedance transceiver circuit consisting of a transmit-receive switch circuit, a class-D amplifier and a transimpedance amplifier (TIA) was newly designed and tested for a nitrogen-14 NQR. An NQR signal at 1.37MHz from imidazole was successfully observed with the dead time of ~85µs under the high Q transmission (Q~120) and reception (Q~140). The noise performance of the low impedance TIA with an NQR probe was comparable with a commercial low noise 50? amplifier (voltage input noise: 0.25 nV/Hz) which was also connected to the probe. The protection voltage for the pre-amplifier using the low impedance transceiver was ~10 times smaller than that for the pre-amplifier using a 50? conventional transceiver, which is suitable for NQR remote sensing applications. PMID:25293696

Sato-Akaba, Hideo

2014-01-01

281

Evidence for d2x-y2 pairing from nuclear-magnetic-resonance experiments in the superconducting state of YBa2Cu3O7  

NASA Astrophysics Data System (ADS)

We calculate the electron spin susceptibility for the superconducting state of YBa2Cu3O7 using a band structure with nearest- and next-nearest-neighbor hopping, a momentum-dependent spin-spin interaction, and a superconducting gap with d2x-y2 symmetry. Our calculated nuclear magnetic relaxation rates and Knight shift agree favorably with experiment. Our work provides further evidence for a d2x-y2 pairing state and demonstrates that antiferromagnetic correlations persist in the superconducting state.

Thelen, D.; Pines, D.; Lu, Jian Ping

1993-04-01

282

87Rb and 85Rb NQR study of phase transitions in RbH3(SeO3)2 J. Seliger, V. 017Dagar, R. Blinc  

E-print Network

dependence of the quadrupole coupling constants and the asymmetry parameters on going into the ferroelectric SeO3. Nous avons confirmé l'existence d'une phase incommensurable intermédiaire entre Tc et Tc + 4 K. Abstract. 2014 The temperature dependence of the nuclear quadrupole resonance spectra of 85Rb and 87Rb

Paris-Sud XI, Université de

283

Humanitarian mine detection by acoustic resonance  

SciTech Connect

The JASON Committee at MITRE Corp. was tasked by DARPA to inquire into suitable technologies for humanitarian mine detection. Acoustic resonance was one of the very few technologies that the JASONs determined might be promising for the task, but was as yet unexplored at the time that they conducted their inquiry. The objective of this Seed Money investigation into acoustic resonance was to determine if it would be feasible to use acoustic resonance to provide an improvement to present methods for humanitarian mine detection. As detailed in this report, acoustic resonance methods do not appear to be feasible for this task. Although acoustic resonant responses are relatively easy to detect when they exist, they are very difficult to excite by the non-contact means that must be used for buried objects. Despite many different attempts, this research did not discover any practical means of using sound to excite resonant responses in objects known to have strong resonances. The shaker table experiments did see an effect that might be attributable to the resonance of the object under test, but the effect was weak, and exploited the a priori knowledge of the resonant frequency of the object under test to distinguish it from the background. If experiments that used objects known to have strong acoustic resonances produced such marginal results, this does not seem to be a practical method to detect objects with weak resonances or non-existent resonances. The results of this work contribute to the ORNL countermine initiative. ORNL is exploring several unconventional mine detection technologies, and is proposed to explore others. Since this research has discovered some major pitfalls in non-metallic mine detection, this experience will add realism to other strategies proposed for mine detection technologies. The experiment provided hands-on experience with inert plastic mines under field conditions, and gives ORNL additional insight into the problems of developing practical field-deployable methods of mine detection.

Kercel, S.W.

1998-03-01

284

Resonant behavior of dielectric objects (electrostatic resonances).  

PubMed

Resonant behavior of dielectric objects occurs at certain frequencies for which the object permittivity is negative and the free-space wavelength is large in comparison with the object dimensions. Unique physical features of these resonances are studied and a novel technique for the calculation of resonance values of permittivity, and hence resonance frequencies, is proposed. Scale invariance of resonance frequencies, unusually strong orthogonality properties of resonance modes, and a two-dimensional phenomenon of "twin" spectra are reported. The paper concludes with brief discussions of optical controllability of these resonances in semiconductor nanoparticles and a plausible, electrostatic resonance based, mechanism for nucleation and formation of ball lightning. PMID:14754117

Fredkin, D R; Mayergoyz, I D

2003-12-19

285

Surface Plasmon Resonance Laboratory  

NSDL National Science Digital Library

This lab focuses on the optical generation and modeling of Surface Plasmons, in particular the attempt of predicting and generating a resonance condition in a three layer system; glass, metal and air. The lab is designed to easily create a film and test itâs resonance with minimal cost and time to prepare the setup between testing. This concept can be demonstrated in a more elaborate setup, but is not necessary unless this demonstration will be used as a research instrument afterwards. This lab is comprised of four main parts: 1. Understanding the theory of SPR, through deriving the Fresnel equations from Maxwell Equations. 2. Determining the optimal conditions for the Prism Coating (Modeling). 3. Fabricating the coated prism with a deposition system. 4. Comparing modeling and experiment, explain error.

Sã¡nchez, Erik

2010-11-24

286

Pygmy dipole resonance  

NASA Astrophysics Data System (ADS)

The pygmy dipole resonance (PDR) is a low-energy debris of the 1hslash? El-strength which is pushed by an isovector residual interaction to higher energies to form the giant dipole resonance. It exhausts about 1% of the EWSR below the particle threshold. High energy resolution experiments performed during the last decade reveal fine structure of the PDR in many nuclei. We report on the studies of the PDR fine structure performed within the Quasiparticle-Phonon model. Excited states are described by a wave function which includes one-, two-, and three-phonon configurations, i.e. the configuration space in calculations below the threshold is almost complete. We discuss also some particular features of the PDR excitation in different nuclear reactions.

Ponomarev, Vladimir

2014-09-01

287

Photorefractivity in WGM resonators  

NASA Technical Reports Server (NTRS)

We report on observation of photorefractive effects in whispering gallery mode resonators made of as-grown and magnesium doped lithium niobate and lithium tantalate in the near as well as far infrared. The effects manifested themselves as dynamic modification of the spectra as well as quality factors of the resonators coupled to the laser radiation. We have observed a significant (exceeding 10-4) change of the ordinary index of refraction of all the materials exposed with 780 nm light. Photorefractive effects have also been detected at 1550 nm. Our experiments support the conclusion that the photorefractivity does not have a distinct red boundary. We show that the maximum saturated refractive index change in the infrared is of the same order of magnitude as in the visible light.

Matsko, Andrey; Savchenkov, Anatoliy; Strekalov, Dmitry; Ilchenko, Vladimir; Maleki, Lute

2006-01-01

288

NQR-NMR studies of higher alcohol synthesis Cu-Co catalysts. Quarterly technical progress report, September 14--December 15, 1990  

SciTech Connect

Copper and cobalt are the key elements in syngas conversion catalyst systems used for higher alcohol synthesis. Their proximity and synergy sensitively control the selectivity and efficiency of the process. It is believed that their outer electronic charge distribution which is responsible for their electrical and magnetic properties might be governing their catalytic properties also. To examine the correlation between catalytic and magnetic properties, a series of copper cobalt catalysts (Co/Cu ratio 5:1 to 5:5) with and without a support were prepared. The nuclear quadrupole resonance spectrum of copper and (zero-field) nuclear magnetic resonance spectrum of cobalt and magnetization and hysteresis character of the catalyst were analyzed. Similar to the catalytic results, the magnetic results also were found to be very sensitive to the preparation technique. The results indicate possible electron exchange between copper and cobalt, and cobalt and the support Titania.

Not Available

1991-01-14

289

All-Resonant Control of Superconducting Resonators  

E-print Network

An all-resonant method is proposed to control the quantum state of superconducting resonators. This approach uses a tunable artificial atom linearly coupled to resonators, and allows for efficient routes to Fock state synthesis, qudit logic operations, and synthesis of NOON states. This resonant approach is theoretically analyzed, and found to perform signficantly better than existing proposals using the same technology.

Frederick W. Strauch

2012-08-17

290

Multiple Ferromagnetic Resonance in Ferrite Spheres  

Microsoft Academic Search

Ferromagnetic resonance experiments have been performed on single crystal spheres of manganese and manganese-zinc ferrites placed in field configurations having large gradients in the rf magnetic field at the sample site. Five major and several minor resonant absorptions are observed extending over a region of 700 oersteds at room temperature. The line spacings are essentially independent of sphere size. The

Robert L. White; Irvin H. Solt

1956-01-01

291

Sequential resonant tunneling in quantum cascade lasers  

SciTech Connect

A model of sequential resonant tunneling transport among two-dimensional subbands that takes into account explicitly elastic scattering is investigated. It is compared to transport measurements performed on quantum cascade lasers, where resonant tunneling processes are known to be dominating. Excellent agreement is found between experiment and theory over a large range of current, temperature, and device structures.

Terazzi, Romain; Gresch, Tobias; Wittmann, Andreas; Faist, Jerome [Quantum Optoelectronics Group, Institute for Quantum Electronics, ETH, 8086 Zuerich (Switzerland)

2008-10-15

292

Resonance Rings  

NSDL National Science Digital Library

This is an activity about resonance and where it is found in related to astronomy. Learners will construct two differently sized rings out of file folder paper and tape them to a piece of cardboard. Next, they will shake the cardboard from side to side, which shakes the rings, and observe what happens when the frequency of the shaking is gradually increased. This activity is from the Stanford Solar Center's All About the Sun: Sun and Stars activity guide for Grades 5-8 and can also accompany the Stanford Solar Center's Build Your Own Spectroscope activity.

293

Precision Electroweak Measurements on the Z Resonance  

Microsoft Academic Search

We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLD experiment using a polarised beam at SLC.

S. Schael; R Barate; R Brunelière; Damir Buskulic; I De Bonis; D Décamp; P Ghez; C Goy; S Jézéquel; J P Lees; A Lucotte; F Martin; E Merle; M N Minard; J Y Nief; P Odier; B Pietrzyk; B Trocmé; S Bravo; M P Casado; M Chmeissani; P Comas; J M Crespo; E Fernández; M Fernández-Bosman; L Garrido; E Graugès-Pous; A Juste; M Martínez; G Merino; R Miquel; L M Mir; S Orteu; A Pacheco; I C Park; J Perlas; I Riu; H Ruiz; F Sánchez; A Colaleo; D Creanza; N De Filippis; M De Palma; G Iaselli; G Maggi; M Maggi; S Nuzzo; A Ranieri; G Raso; F Ruggieri; G Selvaggi; L Silvestris; P Tempesta; A Tricomi; G Zito; X Huang; J Lin; Q Ouyang; T Wang; Y Xie; R Xu; S Xue; J Zhang; L Zhang; W Zhao; D Abbaneo; A Bazarko; U Becker; G Boix; F Bird; E Blucher; B Bonvicini; P Bright-Thomas; T Barklow; M Cattaneo; F Cerutti; B Clerbaux; H Drevermann; R W Forty; M Frank; T C Greening; R Hagelberg; A W Halley; F Gianotti; M Girone; J B Hansen; J Harvey; R Jacobsen; D E Hutchcroft; P Janot; B Jost; J Knobloch; M Kado; Ivan Lehraus; Pierre Lazeyras; P Maley; P Mato; J May; A Moutoussi; M Pepé-Altarelli; F Ranjard; Luigi Rolandi; W D Schlatter; B Schmitt; O Schneider; W Tejessy; F Teubert; I R Tomalin; E Tournefier; R Veenhof; A Valassi; W Wiedenmann; A E Wright; Ziad J Ajaltouni; F Badaud; G Chazelle; O Deschamps; S Dessagne; A Falvard; C Ferdi; D Fayolle; P Gay; C Guicheney; P Henrard; J Jousset; B Michel; S Monteil; J C Montret; D Pallin; J M Pascolo; P Perret; F Podlyski; H Bertelsen; T Fernley; J D Hansen; P H Hansen; A C Kraan; A Lindahl; R Møllerud; B S Nilsson; B Rensch; A Wäänänen; G Daskalakis; A Kyriakis; C Markou; E Simopoulou; I Siotis; A Vayaki; A Blondel; G Bonneaud; J C Brient; F Machefert; A Rougé; M Rumpf; M Swynghedauw; R Tanaka; M Verderi; H L Videau; V Ciulli; E Focardi; G Parrini; K Zachariadou; M Corden; C H Georgiopoulos; A Antonelli; M Antonelli; G Bencivenni; G Bologna; F Bossi; P Campana; G Capon; V Chiarella; G Felici; P Laurelli; G Mannocchi; G P Murtas; L Passalacqua; P Picchi; P Colrain; I ten Have; I S Hughes; J Kennedy; I G Knowles; J G Lynch; W T Morton; P Negus; V O'Shea; C Raine; P Reeves; J M Scarr; K Smith; A S Thompson; R M Turnbull; S R Wasserbaech; O L Buchmüller; R J Cavanaugh; S Dhamotharan; C Geweniger; P Hanke; G Hansper; V Hepp; E E Kluge; A Putzer; J Sommer; K Tittel; W Werner; M Wunsch; R Beuselinck; D M Binnie; W Cameron; G Davies; P J Dornan; S M Goodsir; N Marinelli; E Martin; J Nash; J Nowell; S A Rutherford; J K Sedgbeer; J C Thompson; R White; M D Williams; V M Ghete; P Girtler; E Kneringer; D Kuhn; G Rudolph; E Bouhova-Thacker; C K Bowdery; P G Buck; D P Clarke; G Ellis; A J Finch; F Foster; G Hughes; R W L Jones; N R Keemer; M R Pearson; N A Robertson; T Sloan; M Smizanska; S W Snow; M I Williams; O van der Aa; C Delaere; G Leibenguth; V Lemaître; L A T Bauerdick; U Blumenschein; P Van Gemmeren; I Giehl; F Hölldorfer; K Jakobs; M Kasemann; F Kayser; K Kleinknecht; A S Müller; G Quast; B Renk; E Rohne; H G Sander; S Schmeling; H W Wachsmuth; R Wanke; C Zeitnitz; T Ziegler; Jean-Jacques Aubert; C Benchouk; A Bonissent; J Carr; P Coyle; C Curtil; A Ealet; F Etienne; D Fouchez; F Motsch; P Payre; D Rousseau; M Talby; M Thulasidas; M Aleppo; F Ragusa; V Büscher; A David; H Dietl; G Ganis; K Hüttmann; G Lütjens; C Mannert; W Männer; H G Moser; R Settles; H Seywerd; H Stenzel; M Villegas; G Wolf; J Boucrot; O Callot; S Chen; A Cordier; M Davier; L Duflot; J F Grivaz; P Heusse; A Jacholkowska; F R Le Diberder; J Lefrançois; A M Mutz; M H Schune; L Serin; J J Veillet; I Videau; D Zerwas; P Azzurri; G Bagliesi; S Bettarini; T Boccali; C Bozzi; G Calderini; R Dell'Orso; R Fantechi; I Ferrante; F Fidecaro; L Foà; A Giammanco; A Giassi; A Gregorio; F Ligabue; A Lusiani; P S Marrocchesi; A Messineo; F Palla; G Rizzo; G Sanguinetti; A Sciabà; G Sguazzoni; P Spagnolo; J Steinberger; R Tenchini; C Vannini; A Venturi; P G Verdini; O Awunor; G A Blair; G Cowan; A García-Bellido; M G Green; T Medcalf; J A Strong; P Teixeira-Dias; David R Botterill; R W Clifft; T R Edgecock; M Edwards; S J Haywood; P R Norton; J J Ward; B Bloch-Devaux; D E Boumediene; P Colas; S Emery; B Fabbro; Witold Kozanecki; E Lançon; M C Lemaire; E Locci; P Pérez; J Rander; J F Renardy; A Roussarie; J P Schuller; J Schwindling; B Tuchming; B Vallage; S N Black; J H Dann; H Y Kim; N P Konstantinidis; A M Litke; M A McNeil; G Taylor; C N Booth; S Cartwright; F Combley; P N Hodgson; M H Lehto; L F Thompson; K Affholderbach; E Barberio; A Böhrer; S Brandt; H Burkhardt; E Feigl; C Grupen; J Hess; G Lutters; H Meinhard; J A Minguet-Rodríguez; L Mirabito; A Misiejuk; E Neugebauer; A Ngac; G Prange; F Rivera; P Saraiva; U Schäfer; U Sieler; L Smolik; F Stephan; H Trier; M Apollonio; C Borean; L Bosisio; R Della Marina; G Giannini; B Gobbo; G Musolino; L Pitis; H He; J Pütz; J E Rothberg; S R Armstrong; L Bellantoni; K Berkelman; D Cinabro; J S Conway; K Cranmer

2006-01-01

294

N AND RESONANCES I. Introduction  

E-print Network

) G37 i (2300) H39 d (2350) D35 d (2390) F37 e (2400) G39 n (2420) H3 11 (2750) I3 13­ 1­ N AND RESONANCES I. Introduction The excited states of the nucleon have been studied in a large number of formation and production experiments. The conventional (i.e., Breit-Wigner) masses, pole

295

Extraordinary acoustic transmission mediated by Helmholtz resonators  

SciTech Connect

We demonstrate perfect transmission of sound through a rigid barrier embedded with Helmholtz resonators. The resonators are confined within a waveguide and they are oriented such that one neck protrudes onto each side of the barrier. Perfect sound transmission occurs even though the open area of the necks is less than 3% of the barrier area. Maximum transmission occurs at the resonant frequency of the Helmholtz resonator. Because the dimensions of the Helmholtz resonators are much smaller than the resonant wavelength, the transmission is independent of the direction of sound on the barrier and of the relative placement of the necks. Further, we show that the transmitted sound experiences a continuous phase transition of ? radians as a function of frequency through resonance. In simulations of adjacent resonators with slightly offset resonance frequencies, the phase difference leads to destructive interference. By expanding the simulation to a linear array of tuned Helmholtz resonators we show that it is possible to create an acoustic lens. The ability of Helmholtz resonator arrays to manipulate the phase of a plane acoustic wave enables a new class of sonic beam-forming devices analogous to diffractive optics.

Koju, Vijay [Computation Science Program, Middle Tennessee State University, Murfreesboro, Tennessee 37132 (United States); Rowe, Ebony [Department of Physics and Astronomy, Middle Tennessee State University, Murfreesboro, Tennessee 37132 (United States); Robertson, William M., E-mail: William.Robertson@mtsu.edu [Computation Science Program, Middle Tennessee State University, Murfreesboro, Tennessee 37132 (United States); Department of Physics and Astronomy, Middle Tennessee State University, Murfreesboro, Tennessee 37132 (United States)

2014-07-15

296

Resonance and elastic nonlinear phenomena in rock  

NASA Astrophysics Data System (ADS)

In a great variety of laboratory experiments over large intervals in stress, strain, and frequency, rocks display pronounced nonlinear elastic behavior. Here we describe nonlinear response in rock from resonance experiments. Two important features of nonlinear resonant behavior are a shift in resonant frequency away from the linear resonant frequency as the amplitude of the disturbance is increased and the harmonics in the time signal that accompany this shift. We have conducted Young's mode resonance experiments using bars of a variety of rock types (limestone, sandstone, marble, chalk) and of varying diameters and lengths. Typically, samples with resonant frequencies of approximately 0.5-1.5 kHz display resonant frequency shifts of 10% or more, over strain intervals of 10-7 to 10-6 and under a variety of saturation conditions and ambient pressure conditions. Correspondingly rich harmonic spectra measured from the time signal progressively develop with increasing drive level. In our experiments to date, the resonant peak is observed to always shift downward (if indeed the peak shifts), indicating a net softening of the modulus with drive level. This observation is in agreement with our pulse mode and static test observations, and those of other researchers. Resonant peak shift is not always observed, even at large drive levels; however, harmonics are always observed even in the absence of peak shift when detected strain levels exceed 10-7 or so. This is an unexpected result. Important implications for the classical perturbation model approach to resonance results from this work. Observations imply that stress-strain hysteresis and discrete memory may play an important role in dynamic measurements and should be included in modeling. This work also illustrates that measurement of linear modulus and Q must be undertaken with great caution when using resonance.

Johnson, Paul A.; Zinszner, Bernard; Rasolofosaon, Patrick N. J.

1996-05-01

297

Ultralow Superharmonic Resonance for Functional Nanowires  

E-print Network

New Jersey 08544 ABSTRACT Functional nanowires, made from materials such as zinc oxide, offer of materials such as zinc oxide (ZnO) driven by an oscillating electric field to experi- ence resonance at low

298

Nonmonotonic Energy Dissipation in Microfluidic Resonators  

E-print Network

Nanomechanical resonators enable a range of precision measurements in air or vacuum, but strong viscous damping makes applications in liquid challenging. Recent experiments have shown that fluid damping is greatly reduced ...

Manalis, Scott R.

299

Sb-NQR probe for superconducting properties in the Pr-based filled-skutterudite compound PrRu4Sb12  

Microsoft Academic Search

We report the electronic and superconducting properties in the Pr-based filled-skutterudite superconductor PrRu4Sb12 with Tc=1.3 K via the measurements of nuclear-quadrupole-resonance frequency nuQ and nuclear-spin-lattice-relaxation time T1 of Sb nuclei. The temperature dependence of nuQ has revealed the energy scheme of Pr3+ crystal electric field that is consistent with an energy separation DeltaCEF˜70 K between the ground state and the

M. Yogi; H. Kotegawa; Y. Imamura; G.-Q. Zheng; Y. Kitaoka; H. Sugawara; H. Sato

2003-01-01

300

Resonant and non-resonant tunneling through a double barrier  

NASA Astrophysics Data System (ADS)

An explicit expression is obtained for the phase-time corresponding to tunneling of a (non-relativistic) particle through two rectangular barriers, both in the case of resonant and in the case of non-resonant tunneling. It is shown that the behavior of the transmission coefficient and of the tunneling phase-time near a resonance is given by expressions with "Breit-Wigner type" denominators. By contrast, it is shown that, when the tunneling probability is low (but not negligible), the non-resonant tunneling time depends on the barrier width and on the distance between the barriers only in a very weak (exponentially decreasing) way: This can imply in various cases, as well known, the highly superluminal tunneling associated with the so-called "generalized Hartman Effect": but we are now able to improve and modify the mathematical description of such an effect, and to compare more in detail our results with the experimental data for non-resonant tunneling of photons. Finally, as a second example, the tunneling phase-time is calculated, and compared with the available experimental results, in the case of the quantum-mechanical tunneling of neutrons through two barrier-filters at the resonance energy of the set-up. Our analysis appears to explain satisfactorily both sets of experiments.

Olkhovsky, V. S.; Recami, E.; Zaichenko, A. K.

2005-06-01

301

Instrumental Analysis Experiments  

NSDL National Science Digital Library

This site features laboratory experiments for undergraduate instrumental analysis. Topics include data acquisition, control of instrumentation (gas chromatography, polarography, voltammetry, atomic absorption, robots), infrared spectroscopy, liquid chromatography, and nuclear magnetic resonance. Extensive use of LabView, Excel, and computers. Experiments are available for download in PDF format.

Walters, John P.

2011-04-20

302

Empathy in schizophrenia: impaired resonance.  

PubMed

Resonance is the phenomenon of one person unconsciously mirroring the motor actions as basis of emotional expressions of another person. This shared representation serves as a basis for sharing physiological and emotional states of others and is an important component of empathy. Contagious laughing and contagious yawning are examples of resonance. In the interpersonal contact with individuals with schizophrenia we can often experience impaired empathic resonance. The aim of this study is to determine differences in empathic resonance-in terms of contagion by yawning and laughing-in individuals with schizophrenia and healthy controls in the context of psychopathology and social functioning. We presented video sequences of yawning, laughing or neutral faces to 43 schizophrenia outpatients and 45 sex- and age-matched healthy controls. Participants were video-taped during the stimulation and rated regarding contagion by yawning and laughing. In addition, we assessed self-rated empathic abilities (Interpersonal Reactivity Index), psychopathology (Positive and Negative Syndrome Scale in the schizophrenia group resp. Schizotypal Personality Questionnaire in the control group), social dysfunction (Social Dysfunction Index) and executive functions (Stroop, Fluency). Individuals with schizophrenia showed lower contagion rates for yawning and laughing. Self-rated empathic concern showed no group difference and did not correlate with contagion. Low rate of contagion by laughing correlated with the schizophrenia negative syndrome and with social dysfunction. We conclude that impaired resonance is a handicap for individuals with schizophrenia in social life. Blunted observable resonance does not necessarily reflect reduced subjective empathic concern. PMID:19377866

Haker, Helene; Rössler, Wulf

2009-09-01

303

Resonant Nucleation  

E-print Network

We investigate the role played by fast quenching on the decay of metastable (or false vacuum) states. Instead of the exponentially-slow decay rate per unit volume, $\\Gamma_{\\rm HN} \\sim \\exp[-E_b/k_BT]$ ($E_b$ is the free energy of the critical bubble), predicted by Homogeneous Nucleation theory, we show that under fast enough quenching the decay rate is a power law $\\Gamma_{\\rm RN} \\sim [E_b/k_BT]^{-B}$, where $B$ is weakly sensitive to the temperature. For a range of parameters, large-amplitude oscillations about the metastable state trigger the resonant emergence of coherent subcritical configurations. Decay mechanisms for different $E_b$ are proposed and illustrated in a (2+1)-dimensional scalar field model.

Marcelo Gleiser; Rafael Howell

2005-03-16

304

Investigation of the electronic effects in a series of halo derivatives of organosilicon compounds by the method of nuclear quadrupole resonance of 79 Br, 81 Br, and 127 I  

Microsoft Academic Search

1.The NQR spectra of certain bromo and iodo derivatives of organosilicon compounds were investigated.2.The correlation of the NQR frequencies and the quadrupole coupling constants with the induction and conjugation constants of the substituents at the silicon atom was constructed.

G. K. Semin; E. V. Bryukhova; M. A. Kadina; G. V. Frolova

1971-01-01

305

Nuclear quadrupole resonance of Cl 35 , Br 79 , Br 81 , and I 127 of halogen-containing organomercury compounds  

Microsoft Academic Search

1.The NQR spectra of halogens in a number of organomercury compounds of the RHgHal and p-ClC6 H4HgX types were investigated.2.In crystals of the compounds studied, coordination interactions arise between the mercury atoms and the halogens. However, when the type of coordination is preserved within a narrow series of compounds, the changes in the NQR frequencies may be determined by the

A. N. Nesmeyanov; O. Yu. Okhlobystin; E. V. Bryukhova; V. I. Bregadze; D. N. Kravtsov; B. A. Faingor; L. S. Golovchenko; G. K. Semin

1969-01-01

306

Regenerative feedback resonant circuit  

DOEpatents

A regenerative feedback resonant circuit for measuring a transient response in a loop is disclosed. The circuit includes an amplifier for generating a signal in the loop. The circuit further includes a resonator having a resonant cavity and a material located within the cavity. The signal sent into the resonator produces a resonant frequency. A variation of the resonant frequency due to perturbations in electromagnetic properties of the material is measured.

Jones, A. Mark; Kelly, James F.; McCloy, John S.; McMakin, Douglas L.

2014-09-02

307

Static characteristics of voltage resonant dc-to-dc converters with multiple resonant switches  

NASA Astrophysics Data System (ADS)

Voltage resonant converters with multiple resonant switches operating at fixed switching frequency are presented. Resonant switches are connected in parallel so that the power conditioning is achieved by the phase-shift modulation method instead of the switching frequency modulation method. Switching losses are predicted to be very small due to its zero-voltage switching. Steady-state characteristics of the proposed converter are analyzed, and the analytical results are verified by experiments.

Sato, Terukazu; Itami, Kenji; Nakano, Tadao; Harada, Koosuke

1990-09-01

308

Ferrimagnetic Resonance in Rare-Earth Doped Yttrium Iron Garnet. I. Field for Resonance  

Microsoft Academic Search

Resonance experiments have been performed on YIG crystals doped with each of the rare earth ions except Lu, Gd, and Pm. Except for Ce these are thought to replace Y as trivalent ions. This paper presents measurements of the field for resonance in the (110) plane at 1.5°K for each of these samples. In several cases there are also data

J. F. Dillon; J. W. Nielsen

1960-01-01

309

2011 Resonance -1 MECHANICAL RESONANCE  

E-print Network

frequencies depend on the density, diameter, length, and tension of the wire. In both cases they oscillate is balanced by an upward force from the stretched spring. When the mass is displaced from the equilibrium will oscillate with large displacement (and velocity) amplitude. In this experiment we observe displacement

Glashausser, Charles

310

Stochastic resonance in visual sensitivity.  

PubMed

It is well known from psychophysical studies that stochastic resonance, in its simplest threshold paradigm, can be used as a tool to measure the detection sensitivity to fine details in noise contaminated stimuli. In the present manuscript, we report simulation studies conducted in the similar threshold paradigm of stochastic resonance. We have estimated the contrast sensitivity in detecting noisy sine-wave stimuli, with varying area and spatial frequency, as a function of noise strength. In all the cases, the measured sensitivity attained a peak at intermediate noise strength, which indicate the occurrence of stochastic resonance. The peak sensitivity exhibited a strong dependence on area and spatial frequency of the stimulus. We show that the peak contrast sensitivity varies with spatial frequency in a nonmonotonic fashion and the qualitative nature of the sensitivity variation is in good agreement with human contrast sensitivity function. We also demonstrate that the peak sensitivity first increases and then saturates with increasing area, and this result is in line with the results of psychophysical experiments. Additionally, we also show that critical area, denoting the saturation of contrast sensitivity, decreases with spatial frequency and the associated maximum contrast sensitivity varies with spatial frequency in a manner that is consistent with the results of psychophysical experiments. In all the studies, the sensitivities were elevated via a nonlinear filtering operation called stochastic resonance. Because of this nonlinear effect, it was not guaranteed that the sensitivities, estimated at each frequency, would be in agreement with the corresponding results of psychophysical experiments; on the contrary, close agreements were observed between our results and the findings of psychophysical investigations. These observations indicate the utility of stochastic resonance in human vision and suggest that this paradigm can be useful in psychophysical studies. PMID:25398687

Kundu, Ajanta; Sarkar, Sandip

2014-11-15

311

Electroexcitation of nucleon resonances  

SciTech Connect

We review recent progress in the investigation of the electroexcitation of nucleon resonances, both in experiment and in theory. The most accurate results have been obtained for the electroexcitation amplitudes of the four lowest excited states, which have been measured in a range of Q2 up to 8 and 4.5 GeV2 for the Delta(1232)P33, N(1535)S11 and N(1440)P11, N(1520)D13, respectively. These results have been confronted with calculations based on lattice QCD, large-Nc relations, perturbative QCD (pQCD), and QCD-inspired models. The amplitudes for the Delta(1232) indicate large pion-cloud contributions at low Q2 and don't show any sign of approaching the pQCD regime for Q2<7 GeV2. Measured for the first time, the electroexcitation amplitudes of the Roper resonance, N(1440)P11, provide strong evidence for this state as a predominantly radial excitation of a three-quark (3q) ground state, with additional non-3-quark contributions needed to describe the low Q2 behavior of the amplitudes. The longitudinal transition amplitude for the N(1535)S11 was determined and has become a challenge for quark models. Explanations may require large meson-cloud contributions or alternative representations of this state. The N(1520)D13 clearly shows the rapid changeover from helicity-3/2 dominance at the real photon point to helicity-1/2 dominance at Q2 > 0.5 GeV2, confirming a long-standing prediction of the constituent quark model. The interpretation of the moments of resonance transition form factors in terms of transition transverse charge distributions in infinite momentum frame is presented.

Inna Aznauryan, Volker D. Burkert

2012-01-01

312

Sb-NQR probe for superconducting properties in the Pr-based filled-skutterudite compound PrRu4Sb12  

NASA Astrophysics Data System (ADS)

We report the electronic and superconducting properties in the Pr-based filled-skutterudite superconductor PrRu4Sb12 with Tc=1.3 K via the measurements of nuclear-quadrupole-resonance frequency ?Q and nuclear-spin-lattice-relaxation time T1 of Sb nuclei. The temperature dependence of ?Q has revealed the energy scheme of Pr3+ crystal electric field that is consistent with an energy separation ?CEF˜70 K between the ground state and the first-excited state. In the normal state, the Korringa relation of (1/T1T)Pr=const is valid, with [(1/T1T)Pr/(1/T1T)La]1/2˜1.44, where (1/T1T)La is for LaRu4Sb12. These results are understood in terms of a conventional Fermi-liquid picture in which the Pr-4f2 state derives neither magnetic nor quadrupolar degrees of freedom at low temperatures. In the superconducting state, 1/T1 shows a distinct coherence peak just below Tc, followed by an exponential decrease with a value of 2?/kBTc=3.1. These results demonstrate that PrRu4Sb12 is a typical weak-coupling s-wave superconductor, in strong contrast with the heavy-fermion superconductor PrOs4Sb12 that is in an unconventional strong coupling regime. The present study on PrRu4Sb12 highlights that the Pr-4f2-derived nonmagnetic doublet plays a key role in the unconventional electronic and superconducting properties in PrOs4Sb12.

Yogi, M.; Kotegawa, H.; Imamura, Y.; Zheng, G.-Q.; Kitaoka, Y.; Sugawara, H.; Sato, H.

2003-05-01

313

Resonance neutron capture studies.  

NASA Astrophysics Data System (ADS)

Neutron capture studies taking place at the newly refurbished GELINA pulsed neutron facility are presented. These investigations are of two types: first, the total neutron capture cross section is measured with high resolution in the keV region for isotopes which are particularly interesting for the study of s-process nucleosynthesis. From the obtained resonance parameters and/or capture areas, one can derive the stellar capture rate as a function of the temperature kT. Results have recently been obtained for the bottlenecks 138Ba and 208Pb, and for the s-only isotope 136Ba. A second type of experiment consists of measuring with Ge-detectors primary and secondary gamma-rays from neutron capture in single resonances in an effort to derive their spins and parities. These values are important for the interpretation of the results of parity-non-conservation measurements performed at LANSCE (LANL) by the TRIPLE collaboration. Results have just been obtained for the isotope 109Ag.

Corvi, F.; Athanassopulos, K.; Beer, H.; Mutti, P.; Postma, H.; Zanini, L.

314

Indirect (J) coupling of inequivalent ^75As nuclei in crystalline and glassy As_2Se3 and As_2S_3  

NASA Astrophysics Data System (ADS)

Indirect nuclear spin-spin couplings, or J couplings, were first observed in liquids using nuclear magnetic resonance (NMR) techniques [1]. Because of the nature of the quadrupole Hamiltonian in pure nuclear quadrupole resonance (NQR) experiments J couplings should be observable between inequivalent nuclei [2]. We present results of ^75As NQR measurements in crystalline and glassy As_2S3 and As_2Se_3. These ^75As NQR measurements were performed at various frequencies between about 55 and 75 MHz. The NQR frequency is determined by the electric field gradient (EFG) at the nucleus, and in these materials there are two non-equivalent sites in each of the two crystals. The J coupling can occur through several chemical bonds, and in our case this coupling must go through two As-S covalent bonds since the nearest neighbor As sites are separated by chalcogen atoms. Instead of the monotonic decay expected from relaxation spin-spin theory, the decays of the NQR Hahn echoes following a 90^0-180^0pulse sequence exhibit damped oscillations superimposed on an exponential decay. These damped oscillations can be explained by an indirect coupling (J coupling). Experimental values of the J couplings were obtained from the periods of the oscillations and calculations of the most probable transitions using 2^nd order perturbation theory. The value estimated by this method for the ^2J(^75As-S-^75As) in crystalline As_2S3 compares well with empirical estimates, which are obtained using an existing value of ^2J(^31P-S-^31P) and known scalings with atomic number from the literature. 1. E. L. Hahn and D. E Maxwell, Phys. Rev. 84, 1246 (1951). 2. T. P. Das and E. L. Hahn, Solid State Physics, supp 1, Nuclear Quadrupole Resonance Spectroscopy, p. 28, Academic Press 1958.

Whitaker, J.; Ahn, E.; Hart, P.; Williams, G. A.; Taylor, P. C.; Facelli, J. C.

2004-03-01

315

Virtual magnetic resonance colonography  

PubMed Central

Colorectal cancer screening has vast potential. Beyond considerations for cost and diagnostic accuracy, the effectiveness of any colorectal screening strategy will be dependent on the degree of patient acceptance. Magnetic resonance (MR) colonography has been shown to be accurate regarding the detection of clinically relevant colonic polyps exceeding 10 mm in size, with reported sensitivity and specificity values exceeding 95%. To further increase patient acceptance, strategies for fecal tagging have recently been developed. By modulating the signal of fecal material to be identical to the signal characteristics of the enema applied to distend the colon, fecal tagging in conjunction with MR colonography obviates the need for bowel cleansing. The review will describe the techniques underlying MR colonography and describe early clinical experience with fecal tagging techniques. PMID:12746264

Debatin, J; Lauenstein, T

2003-01-01

316

Composite arrays of superconducting microstrip line resonators  

SciTech Connect

A novel design of an array of half-wave superconductive microstrip resonators is described. The resonator is intended to be useful for electron spin resonance studies of thin film samples at cryogenic temperatures. It achieves a high quality factor, has a small mode-volume, and creates a uniform magnetic field in a plane above the resonator. The device is made of thin film Niobium on sapphire wafer and is tested with a static magnetic field. Variation of Q-factor versus the magnetic field's strength at different temperatures is reported and is in a good agreement with simulation when the loss due to the vortices is included. Also, the power-dependence response of the resonator is shown in experiments and is verified by capturing the nonlinearity associated with the surface impedance of the superconducting film into the circuit model of the device.

Mohebbi, H. R., E-mail: hmohebbi@uwaterloo.ca; Miao, G. X. [Institute for Quantum Computing, Waterloo, Ontario N2L 3G1 (Canada); Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Benningshof, O. W. B. [Institute for Quantum Computing, Waterloo, Ontario N2L 3G1 (Canada); Department of Physics, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada); Taminiau, I. A. J. [Institute for Quantum Computing, Waterloo, Ontario N2L 3G1 (Canada); Cory, D. G. [Institute for Quantum Computing, Waterloo, Ontario N2L 3G1 (Canada); Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2L 2Y5 (Canada); Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

2014-03-07

317

Initial TMX central-cell ICRH experiments  

SciTech Connect

Four topics are discussed in this report: the feasibility of applying ion cyclotron resonance heating (ICRH) in the TMX central cell, some applications of heating, the results of preliminary experiments, and plans for further ICRH experiments.

Molvik, A.W.; Coffield, F.E.; Falabella, S.; Griffin, D.; McVey, B.; Pickles, W.; Poulsen, P.; Simonen, T.C.; Yugo, J.

1980-12-09

318

State-selective Rabi and Ramsey magnetic resonance line shapes G. Xu and D. J. Heinzen  

E-print Network

State-selective Rabi and Ramsey magnetic resonance line shapes G. Xu and D. J. Heinzen Department-selective Rabi and Ramsey magnetic-resonance experiments on ground-state 133 Cs(F 4) atoms. Novel line shapes-selective Rabi and Ramsey magnetic-resonance experiments on 133 Cs at- oms in their 62 S1/2 , F 4 ground

Heinzen, Daniel J.

319

Alpha resonant scattering for astrophysical reaction studies  

NASA Astrophysics Data System (ADS)

Several alpha-induced astrophysical reactions have been studied at CRIB (CNS Radioactive Ion Beam separator), which is a low-energy RI beam separator at Center for Nuclear Study (CNS) of the University of Tokyo. One of the methods to study them is the ? resonant scattering using the thick-target method in inverse kinematics. Among the recent studies at CRIB, the measurement of 7Be+? resonant scattering is discussed. Based on the result of the experiment, we evaluated the contributions of high-lying resonances for the 7Be(?,?) reaction, and proposed a new cluster band in 11C.

Yamaguchi, H.; Kahl, D.; Nakao, T.; Wakabayashi, Y.; Kubano, S.; Hashimoto, T.; Hayakawa, S.; Kawabata, T.; Iwasa, N.; Teranishi, T.; Kwon, Y. K.; Binh, D. N.; Khiem, L. H.; Duy, N. G.

2014-05-01

320

Alpha resonant scattering for astrophysical reaction studies  

SciTech Connect

Several alpha-induced astrophysical reactions have been studied at CRIB (CNS Radioactive Ion Beam separator), which is a low-energy RI beam separator at Center for Nuclear Study (CNS) of the University of Tokyo. One of the methods to study them is the ? resonant scattering using the thick-target method in inverse kinematics. Among the recent studies at CRIB, the measurement of {sup 7}Be+? resonant scattering is discussed. Based on the result of the experiment, we evaluated the contributions of high-lying resonances for the {sup 7}Be(?,?) reaction, and proposed a new cluster band in {sup 11}C.

Yamaguchi, H.; Kahl, D.; Nakao, T. [Center for Nuclear Study (CNS), University of Tokyo, RIKEN campus, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Wakabayashi, Y.; Kubano, S. [The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Hashimoto, T. [Research Center for Nuclear Physics (RCNP), Osaka University, 10-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Hayakawa, S. [Istituto Nazionale Fisica Nucleare - Laboratori Nazionali del Sud (INFN-LNS), Via S. Sofia 62, 95125 Catania (Italy); Kawabata, T. [Department of Physics, Kyoto University, Kita-Shirakawa, Kyoto 606-8502 (Japan); Iwasa, N. [Department of Physics, Tohoku University, Aoba, Sendai, Miyagi 980-8578 (Japan); Teranishi, T. [Department of Physics, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581 (Japan); Kwon, Y. K. [Institute for Basic Science, 70, Yuseong-daero 1689-gil, Yuseong-gu, Daejeon 305-811 (Korea, Republic of); Binh, D. N. [30 MeV Cyclotron Center, Tran Hung Dao Hospital, Hoan Kiem District, Hanoi (Viet Nam); Khiem, L. H.; Duy, N. G. [Institute of Physics, Vietnam Academy of Science and Technology, 18 Hong Quoc Viet, Nghia do, Hanoi (Viet Nam)

2014-05-02

321

[Magnetic resonance imaging of the breasts].  

PubMed

Not even magnetic resonance imaging is a perfect method for imaging of the breasts. Quality of the equipment, imaging parameters as well as the experience and competence of radiographers and radiologists have a significant effect on the final outcome of the study. Since interpretation of magnetic resonance imaging of the breasts is challenging, the radiologist should have access to a comprehensive medical history and previous images, including the reports. Feedback from the reports made and multidisciplinary postoperative meetings are important. Since magnetic resonance imaging is expensive and has low availability, it should be targeted at the correct patient groups. PMID:24340717

Hukkinen, Katja

2013-01-01

322

Integral resonator gyroscope  

NASA Technical Reports Server (NTRS)

The present invention discloses an inertial sensor having an integral resonator. A typical sensor comprises a planar mechanical resonator for sensing motion of the inertial sensor and a case for housing the resonator. The resonator and a wall of the case are defined through an etching process. A typical method of producing the resonator includes etching a baseplate, bonding a wafer to the etched baseplate, through etching the wafer to form a planar mechanical resonator and the wall of the case and bonding an end cap wafer to the wall to complete the case.

Shcheglov, Kirill V. (Inventor); Challoner, A. Dorian (Inventor); Hayworth, Ken J. (Inventor); Wiberg, Dean V. (Inventor); Yee, Karl Y. (Inventor)

2008-01-01

323

Stability Limits in Resonant Planetary Systems  

E-print Network

The relationship between the boundaries for Hill and Lagrange stability in orbital element space is modified in the case of resonantly interacting planets. Hill stability requires the ordering of the planets to remain constant while Lagrange stability also requires all planets to remain bound to the central star. The Hill stability boundary is defined analytically, but no equations exist to define the Lagrange boundary, so we perform numerical experiments to estimate the location of this boundary. To explore the effect of resonances, we consider orbital element space near the conditions in the HD 82943 and 55 Cnc systems. Previous studies have shown that, for non-resonant systems, the two stability boundaries are nearly coincident. However the Hill stability formula are not applicable to resonant systems, and our investigation shows how the two boundaries diverge in the presence of a mean-motion resonance, while confirming that the Hill and Lagrange boundaries are similar otherwise. In resonance the region of stability is larger than the domain defined by the analytic formula for Hill stability. We find that nearly all known resonant interactions currently lie in this extra stable region, i.e. where the orbits would be unstable according to the non-resonant Hill stability formula. This result bears on the dynamical packing of planetary systems, showing how quantifying planetary systems' dynamical interactions (such as proximity to the Hill-stability boundary) provides new constraints on planet formation models.

Rory Barnes; Richard Greenberg

2007-06-25

324

Tailored Asymmetry for Enhanced Coupling to WGM Resonators  

NASA Technical Reports Server (NTRS)

Coupling of light into and out of whispering- gallery-mode (WGM) optical resonators can be enhanced by designing and fabricating the resonators to have certain non-axisymmetric shapes (see figure). Such WGM resonators also exhibit the same ultrahigh values of the resonance quality factor (Q) as do prior WGM resonators. These WGM resonators are potentially useful as tunable narrow-band optical filters having throughput levels near unity, high-speed optical switches, and low-threshold laser resonators. These WGM resonators could also be used in experiments to investigate coupling between high-Q and chaotic modes within the resonators. For a WGM resonator made of an optically nonlinear material (e.g., lithium niobate) or another material having a high index of refraction, a prism made of a material having a higher index of refraction (e.g., diamond) must be used as part of the coupling optics. For coupling of a beam of light into (or out of) the high-Q resonator modes, the beam must be made to approach (or recede from) the resonator at a critical angle determined by the indices of refraction of the resonator and prism materials. In the case of a lithium niobate/diamond interface, this angle is approximately 22 .

Mohageg, Makan; Maleki, Lute

2008-01-01

325

An NMR Kinetics Experiment.  

ERIC Educational Resources Information Center

Outlines advantages of and provides background information, procedures, and typical student data for an experiment determining rate of hydration of p-methyoxyphenylacetylene (III), followed by nuclear magnetic resonance spectroscopy. Reaction rate can be adjusted to meet time framework of a particular laboratory by altering concentration of…

Kaufman, Don; And Others

1982-01-01

326

REVIEW ARTICLE: Electroproduction experiments  

Microsoft Academic Search

A survey is given for recent experiments in electroproduction and a discussion of their results. For the resonance region the main results are that the ratio of longitudinal to transverse excitation is about as small as it was found for the deep inelastic continuum (about 0.2 or smaller). The excitation of the Delta (1236) in the pi 0 channel, as

F. W. Brasse

1972-01-01

327

Nanomechanical resonance detector  

DOEpatents

An embodiment of a nanomechanical frequency detector includes a support structure and a plurality of elongated nanostructures coupled to the support structure. Each of the elongated nanostructures has a particular resonant frequency. The plurality of elongated nanostructures has a range of resonant frequencies. An embodiment of a method of identifying an object includes introducing the object to the nanomechanical resonance detector. A resonant response by at least one of the elongated nanostructures of the nanomechanical resonance detector indicates a vibrational mode of the object. An embodiment of a method of identifying a molecular species of the present invention includes introducing the molecular species to the nanomechanical resonance detector. A resonant response by at least one of the elongated nanostructures of the nanomechanical resonance detector indicates a vibrational mode of the molecular species.

Grossman, Jeffrey C; Zettl, Alexander K

2013-10-29

328

Neutron resonance averaging  

SciTech Connect

The principles of resonance averaging as applied to neutron capture reactions are described. Several illustrations of resonance averaging to problems of nuclear structure and the distribution of radiative strength in nuclei are provided. 30 refs., 12 figs.

Chrien, R.E.

1986-10-01

329

Quantum Criticality in Transition-Metal Oxides  

Microsoft Academic Search

We report on experiments of the bulk susceptibility ?(T), heat capacity C(T)\\/T, resistivity ?(T) and nuclear resonances (NMR and NQR) in order to review evidence of quantum critical behaviour in some metallic transition-metal\\u000a oxides. In analogy to the conventional 4f- and 5f-electron based heavy-fermion compounds, the prerequisites of quantum criticality, i.e. a magnetic phase transition at T=0 accompanied by non-Fermi

N. Büttgen; H.-A. Krug von Nidda; W. Kraetschmer; A. Günther; S. Widmann; S. Riegg; A. Krimmel; A. Loidl

2010-01-01

330

Nuclear Magnetic Resonance  

NASA Astrophysics Data System (ADS)

Author's preface; 1. Introduction; 2. Basic theory; 3. Experimental methods; 4. Measurement of nuclear properties and general physical applications; 5. Nuclear magnetic resonance in liquids and gases; 6. Nuclear magnetic resonance in non-metallic solids; 7. Nuclear magnetic resonance in metals; 8. Quadrupole effects; Appendices 1-6; Glossary of symbols; Bibliography and author index; Subject index.

Andrew, E. R.

2009-06-01

331

Ovenized microelectromechanical system (MEMS) resonator  

DOEpatents

An ovenized micro-electro-mechanical system (MEMS) resonator including: a substantially thermally isolated mechanical resonator cavity; a mechanical oscillator coupled to the mechanical resonator cavity; and a heating element formed on the mechanical resonator cavity.

Olsson, Roy H; Wojciechowski, Kenneth; Kim, Bongsang

2014-03-11

332

Hafnium neutron cross sections and resonance analysis  

NASA Astrophysics Data System (ADS)

The focus of this thesis is to determine resonance parameters for the stable hafnium isotopes in the 0.005--200 eV region, with emphasis on the overlapping 176Hf and 178Hf resonances near 8 eV. The large neutron cross section of hafnium, combined with its corrosion resistance and excellent mechanical properties, make it an ideal material for controlling nuclear reactions. Experiments measuring neutron capture and transmission were performed at the Rensselaer Polytechnic Institute (RPI) LINAC using the time of flight method. Transmission experiments utilized 6Li glass scintillation detectors at flight path lengths of 15 and 25 m. Capture experiments were done using a sixteen section NaI(Tl) multiplicity type detector at a flight path length of 25 m. These experiments utilized various thicknesses of metallic and isotope-enriched liquid samples. The liquid samples were designed to provide information on the 176Hf and 178Hf contributions to the 8 eV doublet without saturation. Data analysis was done using the R-matrix Bayesian fitting code SAMMY version M6 beta. SAMMY is able to account for experimental resolution effects for each of the experimental setups at the RPI LINAC, and also can correct for some of the multiple scattering effects in yield data. The resolution function for specific experimental setups was determined. A method was developed for estimating errors on the fitted resonance parameters due to uncertainties in the resolution function parameters. The combined capture and transmission data analysis yielded resonance parameters for all stable hafnium isotopes from 0.005--200 eV. Resonance integrals were calculated along with errors for each of the hafnium isotopes using the NJOY and INTER codes. The isotopic resonance integrals calculated were significantly different than some of the previous values; however the calculated elemental hafnium resonance integral changed very little.

Trbovich, Michael J.

333

Magnetic resonance on correlated semimetals: the case of U2Ru2Sn, CeRu4Sn6 and FeSb2  

NASA Astrophysics Data System (ADS)

A comparative magnetic resonance study on correlated semiconductors is presented. Nuclear spin-lattice relaxation measurements provide an excellent method to gain local information about the gap formation in this new class of materials. In contrast to U2Ru2Sn (?/kB approx 230 K) in CeRu4Sn6 the gap is slightly reduced (?/kB approx 200 K) and correlations form out of a residual density of states in the gap. For FeSb2 there is revived interest after classifying this system as the second Fe containing Kondo insulator beside FeSi. Surprisingly, FeSb2 shows a colossal Seebeck coefficient at low temperatures. Using 121,123Sb nuclei as a local probe, our NMR/NQR investigations strongly support the gap scenario. The spin-lattice relaxation rate 123(1/T1) in the entire investigated temperature range 2-200 K is perfectly fitted with rectangle DOS model with narrow impurity in-gap band. These in-gap states might originate the high thermopower observed. The obtained gap value is (?/kB approx 473 K).

Gippius, A. A.; Baenitz, M.; Rajarajan, A. K.; Bruening, E. M.; Okhotnikov, K.; Walstedt, R.; Strydom, A.; Mydosh, J.; Steglich, F.

2009-03-01

334

Electrically connected resonant optical antennas.  

PubMed

Electrically connected resonant optical antennas hold promise for the realization of highly efficient nanoscale electro-plasmonic devices that rely on a combination of electric fields and local near-field intensity enhancement. Here we demonstrate the feasibility of such a concept by attaching leads to the arms of a two-wire antenna at positions of minimal near-field intensity with negligible influence on the antenna resonance. White-light scattering experiments in accordance with simulations show that the optical tunability of connected antennas is fully retained. Analysis of the electric properties demonstrates that in the antenna gaps direct current (DC) electric fields of 10(8) V/m can consistently be achieved and maintained over extended periods of time without noticeable damage. PMID:22800440

Prangsma, Jord C; Kern, Johannes; Knapp, Alexander G; Grossmann, Swen; Emmerling, Monika; Kamp, Martin; Hecht, Bert

2012-08-01

335

Optical Helmholtz resonators  

NASA Astrophysics Data System (ADS)

Helmholtz resonators are widely used acoustic components able to select a single frequency. Here, based on an analogy between acoustics and electromagnetism wave equations, we present an electromagnetic 2D Helmholtz resonator made of a metallic slit-box structure. At the resonance, the light is funneled in the ?/800 apertures, and is subsequently absorbed in the cavity. As in acoustics, there is no higher order of resonance, which is an appealing feature for applications such as photodetection or thermal emission. Eventually, we demonstrate that the slit is of capacitive nature while the box behaves inductively. We derive an analytical formula for the resonance wavelength, which does not rely on wave propagation and therefore does not depend on the permittivity of the material filling the box. Besides, in contrast with half-wavelength resonators, the resonance wavelength can be engineered by both the slit aspect ratio and the box area.

Chevalier, Paul; Bouchon, Patrick; Haïdar, Riad; Pardo, Fabrice

2014-08-01

336

Conductive Coupling of Split Ring Resonators: A Path to THz Metamaterials with Ultrasharp Resonances  

NASA Astrophysics Data System (ADS)

We report on a novel metamaterial structure that sustains extremely sharp resonances in the terahertz domain. This system involves two conductively coupled split ring resonators that together exhibit a novel resonance, in broad analogy to the antiphase mode of the so-called Huygens coupled pendulum. Even though this resonance is in principle forbidden in each individual symmetric split ring, our experiments show that this new coupled mode can sustain quality factors that are more than one order of magnitude larger than those of conventional split ring arrangements. Because of the universality of the metamaterial response, the design principle we present here can be applied across the entire electromagnetic spectrum and to various metamaterial resonators.

Al-Naib, Ibraheem; Hebestreit, Erik; Rockstuhl, Carsten; Lederer, Falk; Christodoulides, Demetrios; Ozaki, Tsuneyuki; Morandotti, Roberto

2014-05-01

337

Superconducting coplanar waveguide resonators for low temperature pulsed electron spin resonance spectroscopy  

NASA Astrophysics Data System (ADS)

We discuss the design and implementation of thin film superconducting coplanar waveguide micro-resonators for pulsed electron spin resonance experiments. The performance of the resonators with P doped Si epilayer samples is compared to waveguide resonators under equivalent conditions. The high achievable filling factor even for small sized samples and the relatively high Q-factor result in a sensitivity of 4.5 × 108 spins per shot, which is superior to that of conventional waveguide resonators, in particular to spins close to the sample surface. The peak microwave power is on the order of a few milliwatts, which is compatible with measurements at ultra-low temperatures. We also discuss the effect of the nonuniform microwave magnetic field on the Hahn echo power dependence.

Malissa, H.; Schuster, D. I.; Tyryshkin, A. M.; Houck, A. A.; Lyon, S. A.

2013-02-01

338

Tuning the Resonance in High-Temperature Superconducting Terahertz Metamaterials  

NASA Astrophysics Data System (ADS)

In this Letter, we present resonance properties in terahertz metamaterials consisting of a split-ring resonator array made from high-temperature superconducting films. By varying the temperature, we observe efficient metamaterial resonance switching and frequency tuning. The results are well reproduced by numerical simulations of metamaterial resonance using the experimentally measured complex conductivity of the superconducting film. We develop a theoretical model that explains the tuning features, which takes into account the resistive resonance damping and additional split-ring inductance contributed from both the real and imaginary parts of the temperature-dependent complex conductivity. The theoretical model further predicts more efficient resonance tuning in metamaterials consisting of a thinner superconducting split-ring resonator array, which are also verified in subsequent experiments.

Chen, Hou-Tong; Yang, Hao; Singh, Ranjan; O'Hara, John F.; Azad, Abul K.; Trugman, Stuart A.; Jia, Q. X.; Taylor, Antoinette J.

2010-12-01

339

Three-Dimensional Imaging of Pulmonary Veins by a Novel Steady-State Free-Precession Magnetic Resonance Angiography Technique Without the Use of Intravenous Contrast Agent: Initial Experience  

Microsoft Academic Search

Purpose: To evaluate the feasibility of 3-dimensional (3D) steady-state free-precession (SSFP) magnetic resonance angiography (MRA) using non- selective radiofrequency excitation for imaging of pulmonary veins (PVs) without intravenous gadolinium chelate and to correlate the results with conventional contrast-enhanced MRA (CE-MRA). Material and Methods: Forty consecutive patients with history of atrial fibrillation underwent free-breathing respiratory navigator-gated electrocar- diogram-triggered SSFP MRA without

Mayil S. Krishnam; Anderanik Tomasian; Sachin Malik; Aparna Singhal; Alex Sassani; Gerhard Laub; J. Paul Finn; Stefan Ruehm

2009-01-01

340

Miniature Sapphire Acoustic Resonator - MSAR  

NASA Technical Reports Server (NTRS)

A room temperature sapphire acoustics resonator incorporated into an oscillator represents a possible opportunity to improve on quartz ultrastable oscillator (USO) performance, which has been a staple for NASA missions since the inception of spaceflight. Where quartz technology is very mature and shows a performance improvement of perhaps 1 dB/decade, these sapphire acoustic resonators when integrated with matured quartz electronics could achieve a frequency stability improvement of 10 dB or more. As quartz oscillators are an essential element of nearly all types of frequency standards and reference systems, the success of MSAR would advance the development of frequency standards and systems for both groundbased and flight-based projects. Current quartz oscillator technology is limited by quartz mechanical Q. With a possible improvement of more than x 10 Q with sapphire acoustic modes, the stability limit of current quartz oscillators may be improved tenfold, to 10(exp -14) at 1 second. The electromagnetic modes of sapphire that were previously developed at JPL require cryogenic temperatures to achieve the high Q levels needed to achieve this stability level. However sapphire fs acoustic modes, which have not been used before in a high-stability oscillator, indicate the required Q values (as high as Q = 10(exp 8)) may be achieved at room temperature in the kHz range. Even though sapphire is not piezoelectric, such a high Q should allow electrostatic excitation of the acoustic modes with a combination of DC and AC voltages across a small sapphire disk (approximately equal to l mm thick). The first evaluations under this task will test predictions of an estimated input impedance of 10 kilohms at Q = 10(exp 8), and explore the Q values that can be realized in a smaller resonator, which has not been previously tested for acoustic modes. This initial Q measurement and excitation demonstration can be viewed similar to a transducer converting electrical energy to mechanical energy and back. Such an electrostatic tweeter type excitation of a mechanical resonator will be tested at 5 MHz. Finite element calculation will be applied to resonator design for the desired resonator frequency and optimum configuration. The experiment consists of the sapphire resonator sandwiched between parallel electrodes. A DC+AC voltage can be applied to generate a force to act on a sapphire resonator. With the frequency of the AC voltage tuned to the sapphire resonator frequency, a resonant condition occurs and the sapphire Q can be measured with a high-frequency impedance analyzer. To achieve high Q values, many experimental factors such as vacuum seal, gas damping effects, charge buildup on the sapphire surface, heat dissipation, sapphire anchoring, and the sapphire mounting configuration will need attention. The effects of these parameters will be calculated and folded into the resonator design. It is envisioned that the initial test configuration would allow for movable electrodes to check gap spacing dependency and verify the input impedance prediction. Quartz oscillators are key components in nearly all ground- and space-based communication, tracking, and radio science applications. They play a key role as local oscillators for atomic frequency standards and serve as flywheel oscillators or to improve phase noise in high performance frequency and timing distribution systems. With ultra-stable performance from one to three seconds, an Earth-orbit or moon-based MSAR can enhance available performance options for spacecraft due to elimination of atmospheric path degradation.

Wang, Rabi T.; Tjoelker, Robert L.

2011-01-01

341

Resonance in neocortical neurons and networks.  

PubMed

Neocortical networks produce oscillations that often correspond to characteristic physiological or pathological patterns. However, the mechanisms underlying the generation of and the transitions between such oscillatory states remain poorly understood. In this study, we examined resonance in mouse layer V neocortical pyramidal neurons. To accomplish this, we employed standard electrophysiology to describe cellular resonance parameters. Bode plot analysis revealed a range of resonance magnitude values in layer V neurons and demonstrated that both magnitude and phase response characteristics of layer V neocortical pyramidal neurons are modulated by changes in the extracellular environment. Specifically, increased resonant frequencies and total inductive areas were observed at higher extracellular potassium concentrations and more hyperpolarised membrane potentials. Experiments using pharmacological agents suggested that current through hyperpolarization-activated cyclic nucleotide-gated channels (I(h) ) acts as the primary driver of resonance in these neurons, with other potassium currents, such as A-type potassium current and delayed-rectifier potassium current (Kv1.4 and Kv1.1, respectively), contributing auxiliary roles. The persistent sodium current was also shown to play a role in amplifying the magnitude of resonance without contributing significantly to the phase response. Although resonance effects in individual neurons are small, their properties embedded in large networks may significantly affect network behavior and may have potential implications for pathological processes. PMID:23009328

Dwyer, Jennifer; Lee, Hyong; Martell, Amber; van Drongelen, Wim

2012-12-01

342

Seeing, Acting, Understanding: Motor Resonance in Language Comprehension  

ERIC Educational Resources Information Center

Observing actions and understanding sentences about actions activates corresponding motor processes in the observer-comprehender. In 5 experiments, the authors addressed 2 novel questions regarding language-based motor resonance. The 1st question asks whether visual motion that is associated with an action produces motor resonance in sentence…

Zwaan, Rolf A.; Taylor, Lawrence J.

2006-01-01

343

Modification of piezoelectric vibratory gyroscope resonator parameters by feedback control  

Microsoft Academic Search

A method for analyzing the effect of feedback control on the dynamics of piezoelectric resonators used in vibratory gyroscopes has been developed. This method can be used to determine the feasibility of replacing the traditional mechanical balancing operations, used to adjust the resonant frequency, by displacement feedback and for determining the velocity feedback required to produce a particular bandwidth. Experiments

Philip W. Loveday; Craig A. Rogers

1998-01-01

344

Pulsed Nuclear Magnetic Resonance: Spin Echoes MIT Department of Physics  

E-print Network

Pulsed Nuclear Magnetic Resonance: Spin Echoes MIT Department of Physics (Dated: February 5, 2014) In this experiment, the phenomenon of Nuclear Magnetic Resonance (NMR) is used to determine the magnetic moments-factor in atomic spectroscopy and is given by g = (µ/µN )/I, (2) and µN is the nuclear magneton, e /2mp

Seager, Sara

345

Resonant Column and Cyclic Triaxial Testing of Tailing Dam Material  

Microsoft Academic Search

Aseries of resonant column and cyclic triaxial tests has been conducted in the frame of the analysis of tailing dam stability during earthquakes, The investigation program for a silty sand fro m uranium tailings is presented. The paper describes the testing procedures and presents all significant results of these experiments, Single-stage and multi-stage resonant co­ lumn tests were performed in

S. A. Savidis; C. Vrettos

346

Characterization of microwave magnetic narrow band filters by ferromagnetic resonance  

NASA Astrophysics Data System (ADS)

Ferromagnetic resonance cavity and microstrip excitation experiments have been performed on a straight edge yttrium iron garnet resonator. Both excitation systems have been modeled as band-stop configurations and a mapping from the swept bias magnetic field domain to the frequency domain has been elaborated to compare them in terms of the dispersion and the amplitude of the magnetostatic wave modes.

Bousbahi, Khaled; Marcelli, Romolo

2000-05-01

347

Multi-atom resonant photoemission  

NASA Astrophysics Data System (ADS)

We report here on the first measurements and theoretical considerations of an interatomic multi-atom resonant photoemission (MARPE) effect that can enhance photoelectron intensities by as much as 100% and appears to be generally observable in solid materials. MARPE occurs when the photon energy is tuned to a core-level absorption edge of an atom neighboring the atom from which the photoelectron is being emitted, with the emitting level having a lower binding energy than the resonant level. Large peak intensity enhancements of 30-100% and energy-integrated effects of 10-30% have been seen by our group in various metal oxides and in a metallic system, as well as by other groups now in metal halides and an adsorbate system. The effect has also been observed in solids via the secondary decay processes of Auger emission and fluorescent x-ray emission. Weaker effects also appear to be present in gas-phase electron emission experiments. The range of the effect is so far estimated from both experiment and theory to be about 2-3 nm, with further work needed on this aspect. MARPE should thus provide a new and broadly applicable spectroscopic probe of matter in which the atomic identities and other properties (e.g. magnetic order) of atoms neighboring a given atomic type should be directly derivable. Such interatomic resonance effects also may influence normal x-ray absorption experiments, and in some cases, they may require a consideration of the degree of x-ray beam coherence for their quantitative analysis.

Fadley, Charles S.; Arenholz, Elke; Kay, Alex W.; Garcia de Abajo, Javier; Mun, Bongjin S.; Yang, See-Hun; Hussain, Zahid; Van Hove, Michel

2000-02-01

348

Resonances on hedgehog manifolds  

E-print Network

We discuss resonances for a nonrelativistic and spinless quantum particle confined to a two- or three-dimensional Riemannian manifold to which a finite number of semiinfinite leads is attached. Resolvent and scattering resonances are shown to coincide in this situation. Next we consider the resonances together with embedded eigenvalues and ask about the high-energy asymptotics of such a family. For the case when all the halflines are attached at a single point we prove that all resonances are in the momentum plane confined to a strip parallel to the real axis, in contrast to the analogous asymptotics in some metric quantum graphs; we illustrate it on several simple examples. On the other hand, the resonance behaviour can be influenced by a magnetic field. We provide an example of such a `hedgehog' manifold at which a suitable Aharonov-Bohm flux leads to absence of any true resonance, i.e. that corresponding to a pole outside the real axis.

Pavel Exner; Jiri Lipovsky

2013-02-21

349

Ultraviolet absorption experiment MA-059  

NASA Technical Reports Server (NTRS)

The ultraviolet absorption experiment performed during the Apollo Soyuz mission involved sending a beam of atomic oxygen and atomic nitrogen resonance radiation, strong unabsorbable oxygen and nitrogen radiation, and visual radiation, all filling the same 3 deg-wide field of view from the Apollo to the Soyuz. The radiation struck a retroreflector array on the Soyuz and was returned to a spectrometer onboard the Apollo. The density of atomic oxygen and atomic nitrogen between the two spacecraft was measured by observing the amount of resonance radiation absorbed when the line joining Apollo and Soyuz was perpendicular to their velocity with respect to the ambient atmosphere. Information concerning oxygen densities was also obtained by observation of resonantly fluorescent light. The absorption experiments for atomic oxygen and atomic nitrogen were successfully performed at a range of 500 meters, and abundant resonance fluorescence data were obtained.

Donahue, T. M.; Hudson, R. D.; Anderson, J.; Kaufman, F.; Mcelroy, M. B.

1976-01-01

350

Resonant and antiresonant bouncing droplets  

E-print Network

When placed onto a vibrating liquid bath, a droplet may adopt a permanent bouncing behavior, depending on both the forcing frequency and the forcing amplitude. The relationship between the droplet deformations and the bouncing mechanism is studied experimentally and theoretically through an asymmetric and dissipative bouncing spring model. Antiresonance effects are evidenced. Experiments and theoretical predictions show that both resonance at specific frequencies and antiresonance at Rayleigh frequencies play crucial roles in the bouncing mechanism. In particular, we show that they can be exploited for droplet size selection.

M. Hubert; D. Robert; H. Caps; S. Dorbolo; N. Vandewalle

2014-02-11

351

High beam quality COIL with hybrid resonators  

NASA Astrophysics Data System (ADS)

For a 10kW-class Chemical Oxygen Iodine Laser (COIL), negative and positive branch hybrid resonators are investigated in theory and experiment. Calculations from Fresnel-Kirchhoff theory predict a nearly diffraction limited beam quality in the unstable direction. Theory is verified by measurements with a 2D-camera system in the far field.

Handke, Jürgen; Hall, Thomas; Duschek, Frank; Grünewald, Karin

2007-05-01

352

Nuclear Magnetic Resonance and Magnetic Field Measurements  

NSDL National Science Digital Library

This laboratory is designed for students to become familiar with the principles and detection techniques of Nuclear Magnetic Resonance (NMR), examine the relationship between current and magnetic field in an electromagnet, and gain experience in the use of magnetic field measurement techniques.

2012-01-04

353

Electrodynamics of a ring-shaped spiral resonator  

NASA Astrophysics Data System (ADS)

We present analytical, numerical, and experimental investigations of electromagnetic resonant modes of a compact monofilar Archimedean spiral resonator shaped in a ring, with no central part. Planar spiral resonators are interesting as components of metamaterials for their compact deep-subwavelength size. Such resonators couple primarily to the magnetic field component of the incident electromagnetic wave, offering properties suitable for magnetic meta-atoms. Surprisingly, the relative frequencies of the resonant modes follow the sequence of the odd numbers as f1:f2:f3:f4… = 1:3:5:7…, despite the nearly identical boundary conditions for electromagnetic fields at the extremities of the resonator. In order to explain the observed spectrum of resonant modes, we show that the current distribution inside the spiral satisfies a particular Carleman type singular integral equation. By solving this equation, we obtain a set of resonant frequencies. The analytically calculated resonance frequencies and the current distributions are in good agreement with experimental data and the results of numerical simulations. By using low-temperature laser scanning microscopy of a superconducting spiral resonator, we compare the experimentally visualized ac current distributions over the spiral with the calculated ones. Theory and experiment agree well with each other. Our analytical model allows for calculation of a detailed three-dimensional magnetic field structure of the resonators.

Maleeva, N.; Fistul, M. V.; Karpov, A.; Zhuravel, A. P.; Averkin, A.; Jung, P.; Ustinov, A. V.

2014-02-01

354

Electrodynamics of a ring-shaped spiral resonator  

SciTech Connect

We present analytical, numerical, and experimental investigations of electromagnetic resonant modes of a compact monofilar Archimedean spiral resonator shaped in a ring, with no central part. Planar spiral resonators are interesting as components of metamaterials for their compact deep-subwavelength size. Such resonators couple primarily to the magnetic field component of the incident electromagnetic wave, offering properties suitable for magnetic meta-atoms. Surprisingly, the relative frequencies of the resonant modes follow the sequence of the odd numbers as f{sub 1}:f{sub 2}:f{sub 3}:f{sub 4}…?=?1:3:5:7…, despite the nearly identical boundary conditions for electromagnetic fields at the extremities of the resonator. In order to explain the observed spectrum of resonant modes, we show that the current distribution inside the spiral satisfies a particular Carleman type singular integral equation. By solving this equation, we obtain a set of resonant frequencies. The analytically calculated resonance frequencies and the current distributions are in good agreement with experimental data and the results of numerical simulations. By using low-temperature laser scanning microscopy of a superconducting spiral resonator, we compare the experimentally visualized ac current distributions over the spiral with the calculated ones. Theory and experiment agree well with each other. Our analytical model allows for calculation of a detailed three-dimensional magnetic field structure of the resonators.

Maleeva, N.; Karpov, A.; Averkin, A. [Laboratory of Superconducting Metamaterials, National University of Science and Technology “MISIS,” Moscow 119049 (Russian Federation); Fistul, M. V. [Laboratory of Superconducting Metamaterials, National University of Science and Technology “MISIS,” Moscow 119049 (Russian Federation); Theoretische Physik III, Ruhr-Universität Bochum, Bochum 44801 (Germany); Zhuravel, A. P. [B. Verkin Institute of Low Temperature Physics and Engineering, National Academy of Sciences of Ukraine, Kharkov 61103 (Ukraine); Jung, P. [Physikalisches Institut, Karlsruhe Institute of Technology (KIT), Karlsruhe 76131 (Germany); Ustinov, A. V. [Laboratory of Superconducting Metamaterials, National University of Science and Technology “MISIS,” Moscow 119049 (Russian Federation); Physikalisches Institut, Karlsruhe Institute of Technology (KIT), Karlsruhe 76131 (Germany)

2014-02-14

355

Resonant x-ray magnetic scattering in holmium  

SciTech Connect

We review the results of resonant x-ray magnetic scattering experiments on the rare earth metal holmium. When the incident incident x-ray energy is tuned near the L{sub III} absorption edge, large resonant enhancements of the magnetic scattering and resonant integer harmonics are observed. These results are analyzed within the theory of x-ray resonance exchange scattering assuming electric dipole (2p {yields} 5d) and quadrupole (2p {yields} 4f) transitions among atomic orbitals. 30 refs., 5 figs.

Gibbs, D.

1991-01-01

356

Localized ferromagnetic resonance force microscopy of permalloy-cobalt films  

SciTech Connect

We report the Ferromagnetic Resonance Force Microscopy (FMRFM) experiments on a combined permalloy-cobalt continuous film. Our studies demonstrate the capability of FMRFM to perform local spectroscopy of different ferromagnetic materials. Theoretical analysis of the uniform resonance mode at the edge of the film provides good quantitative agreement with the experimental data. Our experiments demonstrate the micron scale lateral resolution and allow to extract local magnetic properties in continuous ferromagnetic samples.

Nazaretski, Evgueni [Los Alamos National Laboratory; Movshovich, Roman [Los Alamos National Laboratory; Martin, Ivar [Los Alamos National Laboratory; Cha, Kitty V [Los Alamos National Laboratory; Akhadov, Elshan A [Los Alamos National Laboratory; Obukhov, Yu [OH STATE U; Pelekhov, D C [OH STATE U; Hammel, P C [OH STATE U

2008-01-01

357

35Cl nuclear quadrupolar resonance study of 4,4'-dichlorobiphenyl sulphone  

Microsoft Academic Search

Pulsed NQR spectroscopy was used to search for a structural phase transition from a normal to an incommensurate phase and others in 4,4'-dichlorobiphenyl sulphone. The experimental results show the existence of a structural phase transition to an incommensurate phase at 150 K and another transition to a possible commensurate phase at 110 K.

J. M. Corberó; A. E. Wolfenson; D. J. Pusiol; A. H. Brunetti

1986-01-01

358

Resonant control of solitons  

NASA Astrophysics Data System (ADS)

It is shown that the effect of “scattering on resonance” can be used to control envelope solitons in the driven nonlinear Schrödinger equation. The control occurs by the frequency modulated driving with multiple crossing of the resonant frequency of the soliton.

Batalov, S. V.; Shagalov, A. G.

2013-05-01

359

Nanoengineering of optical resonances  

Microsoft Academic Search

Metal nanoshells, consisting of a dielectric core with a metallic shell of nanometer thickness, are a new, composite nanoparticle whose optical resonance can be “designed in” in a controlled manner. By varying the relative dimensions of the core and shell, the optical resonance of these nanoparticles can be varied over hundreds of nanometers in wavelength, across the visible and into

S. J. Oldenburg; R. D. Averitt; S. L. Westcott; N. J. Halas

1998-01-01

360

Nuclear Quadrupole Resonance  

Microsoft Academic Search

Nuclear quadrupole resonance is a recently developed branch of radio-frequency spectroscopy which is concerned with magnetic resonance absorption in crystals. This absorption is due to reorientation of the nonspherical atomic nuclei against crystalline electric fields. Related phenomena in isolated molecules are briefly mentioned in the Introduction A. This is followed in Sec. B by an elementary treatment of the electrostatic

H. G. Dehmelt

1954-01-01

361

Helioseismology The Resonant Sun  

E-print Network

Helioseismology The Resonant Sun Professor Bill Chaplin, School of Physics & Astronomy University Eddington #12;The Unseen Interior ''At first sight it would seem that the deep interior of the sun and stars;Overview What are resonant oscillations of the Sun? How do we observe the oscillations? What can we learn

362

The resonator handbook  

NASA Technical Reports Server (NTRS)

The purpose of this work is to extend resonator theory into the region in which the planar mirror is quite small. Results of the theoretical description are then extended to resonator design and experimental arrangements as discussed in further sections of this work. Finally, a discussion of dielectric measurements for small samples is included as a specific application of this work.

Cook, Jerry D.; Zhou, Shiliang

1993-01-01

363

MEMS resonator temperature compensation  

Microsoft Academic Search

This paper presents the study of an electromechanical resonator temperature compensation principle. It consists in the use of a coating material presenting opposite properties over temperature compared to the silicon resonator structural material. Simulated results, using the FEM Coventor® software, show the great potential of this CMOS compatible principle for industrial perspectives.

F. Casset; C. Durand; Y. Civet; E. Ollier; J. F. Carpentier; P. Ancey; P. Robert

2010-01-01

364

Observation of Resonant Behavior in the Energy Velocity of Diffused Light R. Sapienza,1,  

E-print Network

Observation of Resonant Behavior in the Energy Velocity of Diffused Light R. Sapienza,1, P. D Espan~a (Received 12 March 2007; published 5 December 2007) In this Letter we demonstrate Mie resonances fractions. By means of both static and dynamic optical experiments we show resonant behavior in the key

Viña, Luis

365

Electrically small isotropic three-dimensional magnetic resonators for metamaterial design  

Microsoft Academic Search

The problem of the design of artificial magnetic resonators for isotropic metamaterials is addressed. The internal symmetries that ensure an isotropic behavior of such resonators are analyzed and some specific designs based on the proper arrangement of modified split ring resonators are proposed. These proposals are validated by electromagnetic simulations and experiments. The reported results are likely to have applications

J. D. Baena; L. Jelinek; R. Marqués; J. Zehentner

2006-01-01

366

Resonant snubber inverter  

DOEpatents

A resonant, snubber-based, soft switching, inverter circuit achieves lossless switching during dc-to-ac power conversion and power conditioning with minimum component count and size. Current is supplied to the resonant snubber branches solely by the main inverter switches. Component count and size are reduced by use of a single semiconductor switch in the resonant snubber branches. Component count is also reduced by maximizing the use of stray capacitances of the main switches as parallel resonant capacitors. Resonance charging and discharging of the parallel capacitances allows lossless, zero voltage switching. In one embodiment, circuit component size and count are minimized while achieving lossless, zero voltage switching within a three-phase inverter. 14 figs.

Lai, J.S.; Young, R.W. Sr.; Chen, D.; Scudiere, M.B.; Ott, G.W. Jr.; White, C.P.; McKeever, J.W.

1997-06-24

367

Polaritonic Feshbach resonance  

NASA Astrophysics Data System (ADS)

A Feshbach resonance occurs when the energy of two interacting free particles comes into resonance with a molecular bound state. When approaching this resonance, marked changes in the interaction strength between the particles can arise. Feshbach resonances provide a powerful tool for controlling the interactions in ultracold atomic gases, which can be switched from repulsive to attractive, and have allowed a range of many-body quantum physics effects to be explored. Here we demonstrate a Feshbach resonance based on the polariton spinor interactions in a semiconductor microcavity. By tuning the energy of two polaritons with anti-parallel spins across the biexciton bound state energy, we show an enhancement of attractive interactions and a prompt change to repulsive interactions. A mean-field two-channel model quantitatively reproduces the experimental results. This observation paves the way for a new tool for tuning polariton interactions and to move forward into quantum correlated polariton physics.

Takemura, N.; Trebaol, S.; Wouters, M.; Portella-Oberli, M. T.; Deveaud, B.

2014-07-01

368

Resonant snubber inverter  

DOEpatents

A resonant, snubber-based, soft switching, inverter circuit achieves lossless switching during dc-to-ac power conversion and power conditioning with minimum component count and size. Current is supplied to the resonant snubber branches solely by the main inverter switches. Component count and size are reduced by use of a single semiconductor switch in the resonant snubber branches. Component count is also reduced by maximizing the use of stray capacitances of the main switches as parallel resonant capacitors. Resonance charging and discharging of the parallel capacitances allows lossless, zero voltage switching. In one embodiment, circuit component size and count are minimized while achieving lossless, zero voltage switching within a three-phase inverter.

Lai, Jih-Sheng (Knoxville, TN); Young, Sr., Robert W. (Oak Ridge, TN); Chen, Daoshen (Knoxville, TN); Scudiere, Matthew B. (Oak Ridge, TN); Ott, Jr., George W. (Knoxville, TN); White, Clifford P. (Knoxville, TN); McKeever, John W. (Oak Ridge, TN)

1997-01-01

369

Study on Dynamic Alignment Technology of COIL Resonator  

NASA Astrophysics Data System (ADS)

The performance of great power chemical oxygen-iodine laser (COIL) beam is decided mostly by resonator mirror maladjustment and environment vibration. To improve the performance of light beam, an auto-alignment device is used in COIL resonator, the device can keep COIL resonator collimating by adjusting the optical components of resonator. So the coupling model of COIL resonator is present. The multivariable self study fuzzy uncoupling arithmetic and six-dimensional micro drive technology are used to design a six-input-three-output uncoupling controller, resulting in the realization of the high precision dynamic alignment. The experiments indicate that the collimating range of this system is 8 mrad, precision is 5 urad and frequency response is 20Hz, which meet the demand of resonator alignment system.

Xiong, M. D.; Zou, X. J.; Guo, J. H.; Jia, S. N.; Zhang2, Z. B.

2006-10-01

370

Giant resonances in single and double charge exchange  

SciTech Connect

A long-standing issue in nuclear physics is whether or not multiple excitations of the giant-dipole resonance do exist. Recent studies at LAMPF using pion-induced double-charge exchange reactions show the existence of previously unobserved giant resonances in the continuum at high-excitation energies. Based on their energies, characteristic angular distributions, and the cross sections at which the resonances are observed, they have been identified as two different types of double-collective-excitation modes of the nucleus: (1) The isovector giant-dipole resonance built on the isobaric analog state and (2) the isovector giant-dipole resonance built on the giant dipole. In this report we will discuss the general features of the new resonances as they have emerged from DCX experiments performed recently at LAMPF. 12 refs., 7 figs.

Mordechai, S. (Ben-Gurion Univ. of the Negev, Beersheba (Israel) Texas Univ., Austin, TX (United States)); Moore, C.F. (Texas Univ., Austin, TX (United States))

1991-01-01

371

Conductively coupled resonator scheme for dispersive transparency in metamaterials  

NASA Astrophysics Data System (ADS)

We present and demonstrate a new type of single resonator based planar metamaterial exhibiting electromagnetically induced transparency (EIT)-like transmission behavior. The novel design involves physically coupled split-ring resonator (SRR) and a dipolar ring as opposed to many inductively coupled resonators explored in the past. Both experiments and simulations reveal a dispersive transparency due to coupled resonances and the underlying mechanism. Further, the conductive and inductive coupling scenarios for this structure were compared where conductive coupling was found to coerce the direction of light induced currents and stronger in effect than inductive coupling. Resonance tuning is achieved by moving the bar coupling SRR and the ring. Hence, we show that conductive coupling has potential in tailoring coupled resonances of desired quality factor and fabricating metamaterials for enhanced sensing.

Turaga, Shuvan Prashant; Wu, Jianfeng; Banas, Agnieszka; Banas, Krzysztof; Bettiol, Andrew A.

2014-11-01

372

Resonant quantum transitions in trapped antihydrogen atoms.  

PubMed

The hydrogen atom is one of the most important and influential model systems in modern physics. Attempts to understand its spectrum are inextricably linked to the early history and development of quantum mechanics. The hydrogen atom's stature lies in its simplicity and in the accuracy with which its spectrum can be measured and compared to theory. Today its spectrum remains a valuable tool for determining the values of fundamental constants and for challenging the limits of modern physics, including the validity of quantum electrodynamics and--by comparison with measurements on its antimatter counterpart, antihydrogen--the validity of CPT (charge conjugation, parity and time reversal) symmetry. Here we report spectroscopy of a pure antimatter atom, demonstrating resonant quantum transitions in antihydrogen. We have manipulated the internal spin state of antihydrogen atoms so as to induce magnetic resonance transitions between hyperfine levels of the positronic ground state. We used resonant microwave radiation to flip the spin of the positron in antihydrogen atoms that were magnetically trapped in the ALPHA apparatus. The spin flip causes trapped anti-atoms to be ejected from the trap. We look for evidence of resonant interaction by comparing the survival rate of trapped atoms irradiated with microwaves on-resonance to that of atoms subjected to microwaves that are off-resonance. In one variant of the experiment, we detect 23 atoms that survive in 110 trapping attempts with microwaves off-resonance (0.21 per attempt), and only two atoms that survive in 103 attempts with microwaves on-resonance (0.02 per attempt). We also describe the direct detection of the annihilation of antihydrogen atoms ejected by the microwaves. PMID:22398451

Amole, C; Ashkezari, M D; Baquero-Ruiz, M; Bertsche, W; Bowe, P D; Butler, E; Capra, A; Cesar, C L; Charlton, M; Deller, A; Donnan, P H; Eriksson, S; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Gutierrez, A; Hangst, J S; Hardy, W N; Hayden, M E; Humphries, A J; Isaac, C A; Jonsell, S; Kurchaninov, L; Little, A; Madsen, N; McKenna, J T K; Menary, S; Napoli, S C; Nolan, P; Olchanski, K; Olin, A; Pusa, P; Rasmussen, C Ø; Robicheaux, F; Sarid, E; Shields, C R; Silveira, D M; Stracka, S; So, C; Thompson, R I; van der Werf, D P; Wurtele, J S

2012-03-22

373

Resonance searches with the $t\\overline{t}$ Invariant Mass Distribution measured with the D\\O\\, Experiment at $\\sqrt{s}=1.96\\,\\textrm{TeV}  

SciTech Connect

Understanding the universe, its birth and its future is one of the biggest motivations in physics. In order to understand the cosmos, the fundamental particles forming the universe, the components our matter is built of need to be known and understood. Over time physicists have built a theory which describes the physics of the known fundamental particles very well: the Standard Model (SM) of particle physics. The SM describes the particles, their interactions and phenomena with high precision. So far no proven deviations from the SM have been found, though recently evidence for possible physics beyond the SM has been observed. The SM is not describing the mass of the elementary particles however and even with the addition of the Higgs mechanism giving mass to the particles, we have no full theory for all four fundamental forces. We know the model needs to be extended or replaced by another one, as gravitation is not included in the SM. Having a theory which describes all fundamental particles found so far and all but one fundamental interaction is a great success. However, all this describes about 4% of the universe we live in. 23% is dark matter and 73% is dark energy. Dark matter is believed to interact only through gravity and maybe the weak force, which makes it hardly observable. Dark energy is even more elusive. Among other theories the cosmologic constant and scalar fields are discussed to describe it. One should also note that other models exist which for example modify the Newtonian law of gravity. The Higgs mechanism has become the most popular model for mass generation. Alternative theories like Super Symmetry (SUSY), large Extra Dimensions, Technicolor, String Theory, to name just a few, have spread to describe the necessary mass generation or new particles. As proof for new physics beyond the SM has not been found yet, one assumes that new physics will manifest itself at a larger energy scale and therefore a higher particle mass. Particles with high masses are therefore presumed to be a window to test the SM for deviations caused by new physics. The heaviest fundamental particle which is in our reach is the top quark. Its mass is almost as large as that of a complete tungsten atom. It is so heavy, that it decays faster than it can hadronize. It seems the perfect probe to study new physics at the moment. In this analysis the top quark is used as a probe to search for a new resonance, whose properties are similar to a SM Z boson but is much more massive. This analysis will study t{bar t} decays to search for an excess in the invariant mass distribution of the t{bar t} pairs. Resonant states are suggested for massive Z-like bosons in extended gauge theories, Kaluza Klein states of the gluon or Z, axigluons, topcolor, and other beyond the Standard Model theories. Independent of the exact model a resonant production mechanism should be visible in the t{bar t} invariant mass distribution. In this thesis a model-independent search for a narrow-width heavy resonance X decaying into t{bar t} is performed. In the SM, the top quark decays into a W boson and a b quark nearly 100% of the time, which has been proven experimentally, too. The t{bar t} event signature is fully determined by the W boson decay modes. In this analysis, only the lepton+jets final state, which results from the leptonic decay of one of the W bosons and the hadronic decay of the other, is considered. The event signature is an isolated electron or muon with high transverse momentum, large transverse energy imbalance due to the undetected neutrino, and at least three jets, two of which result from the hadronization of b quarks.

Schliephake, Thorsten Dirk; /Wuppertal U.

2010-06-01

374

Resonant Auger studies of metallic systems  

SciTech Connect

Results of resonant Auger spectroscopy experiments are presented for Cu, Co, and oxidized Al. Sub-lifetime narrowing of Auger spectra and generation of sub-lifetime narrowed absorption spectra constructed from Auger yield measurements, were observed. Resonant Auger yields are used to identify three valence states of oxidized Al. Partial absorption yield spectra were derived giving detailed electronic information and thickness information for the various chemical states of the bulk metal, the passivating aluminum oxide layer, and the metal-oxide interface region. In addition, the total absorption yield spectrum for the oxidized Al sample was constructed from the partial yield data, supporting the consistency of the authors method.

Coulthard, I.; Antel, W. J., Jr.; Frigo, S. P.; Freeland, J. W.; Moore, J.; Calaway, W. S.; Pellin, M. J.; Mendelsohn, M.; Sham, T. K.; Naftel, S. J.; Stampfl, A. P. J.

1999-10-21

375

Suppression of Helmholtz resonance using inside acoustic liner  

NASA Astrophysics Data System (ADS)

When a Helmholtz resonator is exposed to grazing flow, an unstable shear layer at the opening can cause the occurrence of acoustic resonance under appropriate conditions. In this paper, in order to suppress the flow-induced resonance, the effects of inside acoustic liners placed on the side wall or the bottom of a Helmholtz resonator are investigated. Based on the one-dimensional sound propagation theory, the time domain impedance model of a Helmholtz resonator with inside acoustic liner is derived, and then combined with a discrete vortex model the resonant behavior of the resonator under grazing flow is simulated. Besides, an experiment is conducted to validate the present model, showing significant reduction of the peak sound pressure level achieved by the use of the side-wall liners. And the simulation results match reasonably well with the experimental data. The present results reveal that the inside acoustic liner can not only absorb the resonant sound pressure, but also suppress the fluctuation motion of the shear layer over the opening of the resonator. In all, the impact of the acoustic liners is to dampen the instability of the flow-acoustic coupled system. This demonstrates that it is a convenient and effective method for suppressing Helmholtz resonance by using inside acoustic liner.

Hong, Zhiliang; Dai, Xiwen; Zhou, Nianfa; Sun, Xiaofeng; Jing, Xiaodong

2014-08-01

376

Microwave Oscillators Based on Nonlinear WGM Resonators  

NASA Technical Reports Server (NTRS)

Optical oscillators that exploit resonantly enhanced four-wave mixing in nonlinear whispering-gallery-mode (WGM) resonators are under investigation for potential utility as low-power, ultra-miniature sources of stable, spectrally pure microwave signals. There are numerous potential uses for such oscillators in radar systems, communication systems, and scientific instrumentation. The resonator in an oscillator of this type is made of a crystalline material that exhibits cubic Kerr nonlinearity, which supports the four-photon parametric process also known as four-wave mixing. The oscillator can be characterized as all-optical in the sense that the entire process of generation of the microwave signal takes place within the WGM resonator. The resonantly enhanced four-wave mixing yields coherent, phase-modulated optical signals at frequencies governed by the resonator structure. The frequency of the phase-modulation signal, which is in the microwave range, equals the difference between the frequencies of the optical signals; hence, this frequency is also governed by the resonator structure. Hence, further, the microwave signal is stable and can be used as a reference signal. The figure schematically depicts the apparatus used in a proof-of-principle experiment. Linearly polarized pump light was generated by an yttrium aluminum garnet laser at a wavelength of 1.32 microns. By use of a 90:10 fiber-optic splitter and optical fibers, some of the laser light was sent into a delay line and some was transmitted to one face of glass coupling prism, that, in turn, coupled the laser light into a crystalline CaF2 WGM disk resonator that had a resonance quality factor (Q) of 6x10(exp 9). The output light of the resonator was collected via another face of the coupling prism and a single-mode optical fiber, which transmitted the light to a 50:50 fiber-optic splitter. One output of this splitter was sent to a slow photodiode to obtain a DC signal for locking the laser to a particular resonator mode. The other output of this splitter was combined with the delayed laser signal in another 50:50 fiber-optic splitter used as a combiner. The output.of the combiner was fed to a fast photodiode that demodulated light and generated microwave signal. In this optical configuration, the resonator was incorporated into one arm of a Mach-Zehnder interferometer, which was necessary for the following reasons: It was found that when the output of the resonator was sent directly to a fast photodiode, the output of the photodiode did not include a measurable microwave signal. However, when the resonator was placed in an arm of the interferometer and the delay in the other arm was set at the correct value, the microwave signal appeared. Such behavior is distinctly characteristic of phase-modulated light. The phase-modulation signal had a frequency of about 8 GHz, corresponding to the free spectral range of the resonator. The spectral width of this microwave signal was less than 200 Hz. The threshold pump power for generating the microwave signal was about 1 mW. It would be possible to reduce the threshold power by several orders of magnitude if resonators could be made from crystalline materials in dimensions comparable to those of micro-resonators heretofore made from fused silica.

Maleki, Lute; Matsko, Andrey; Savchenkov, Anatoliy; Strekalov, Dmitry

2006-01-01

377

Evidence for Unconventional Strong-Coupling Superconductivity in PrOs4Sb12: An Sb Nuclear Quadrupole Resonance Study  

Microsoft Academic Search

We report Sb-NQR results which evidence a heavy-fermion (HF) behavior and an unconventional superconducting (SC) property in Pr(Os4Sb12 with Tc=1.85 K. The temperature (T) dependence of nuclear-spin-lattice-relaxation rate, 1\\/T1, and NQR frequency unravel a low-lying crystal-electric-field splitting below T0˜10 K, associated with Pr3+(4f2)-derived ground state. In the SC state, 1\\/T1 shows neither a coherence peak just below Tc K nor

H. Kotegawa; M. Yogi; Y. Imamura; Y. Kawasaki; G.-Q. Zheng; Y. Kitaoka; S. Ohsaki; H. Sugawara; Y. Aoki; H. Sato

2003-01-01

378

LABCOM resonator Phase 3  

SciTech Connect

The purpose of this project was to develop quartz crystal resonator designs, production processes, and test capabilities for 5-MHz, 6.2-MHz, and 10-MHz resonators for Tactical Miniature Crystal Oscillator (TMXO) applications. GE Neutron Devices (GEND) established and demonstrated the capability to produce and test quartz crystal resonators for use in the TMXO developed by the US Army ERADCOM (now LABCOM). The goals in this project were based on the ERADCOM statement of work. The scope of work indicated that the resonator production facilities for this project would not be completely independent, but that they would be supported in part by equipment and processes in place at GEND used in US Department of Energy (DOE) work. In addition, provisions for production test equipment or or eventual technology transfer costs to a commercial supplier were clearly excluded from the scope of work. The demonstrated technical capability of the deep-etched blank design is feasible and practical. It can be manufactured in quantity with reasonable yield, and its performance is readily predictable. The ceramic flatpack is a very strong package with excellent hermeticity. The four-point mount supports the crystal to reasonable shock levels and does not perturb the resonator's natural frequency-temperature behavior. The package can be sealed with excellent yields. The high-temperature, high-vacuum processing developed for the TMXO resonator, including bonding the piezoid to its mount with conductive polyimide adhesive, is consistent with precision resonator fabrication. 1 fig., 6 tabs.

Keres, L.J.

1990-11-01

379

Optical Feshbach Resonances: Field-Dressed Theory and Experimental Comparisons  

E-print Network

Optical Feshbach resonances (OFRs) have generated significant experimental interest in recent years. These resonances are promising for many-body physics experiments, yet the practical application of OFRs has been limited. The theory of OFRs has been based on an approximate model that fails in important detuning regimes, and the incomplete theoretical understanding of this effect has hindered OFR experiments. We present the most complete theoretical treatment of OFRs to date, demonstrating important characteristics that must be considered in OFR experiments and comparing OFRs to the well studied case of magnetic Feshbach resonances. We also present a comprehensive treatment of the approximate OFR model, including a study of the range of validity for this model. Finally, we derive experimentally useful expressions that can be applied to real experimental data to extract important information about the resonance structure of colliding atoms.

Nicholson, T L; Bloom, B J; Williams, J R; Thomsen, J W; Ye, J; Julienne, P S

2015-01-01

380

Proton resonance for oscillating field of the order of static magnetic field  

Microsoft Academic Search

A spin decoupling method in nuclear quadrupole resonance spin echo experiment is used to detect the proton magnetic resonance absorption spectrum. The behavior of proton resonance in ? phase of polycrystalline p-dichlorobenzene as a function of the intensity of the proton decoupling oscillating field (H2) is measured. Good agreement between the experimental resonance frequency and Shirley’s theory for a non-interacting

Clemar Schurrer; Silvina Pérez; Alberto Wolfenson

2010-01-01

381

Self-radiation from arrays of niobium Josephson junctions embedded in the open resonator  

NASA Astrophysics Data System (ADS)

This paper focuses on self-radiation from arrays of Josephson junctions embedded in a quasi-optical resonator. The mechanism of coupling this radiation to the principal mode of the open resonator is illustrated using experiments and simulations with CST microwave studio software. Comparing the microstrips and dielectric resonators used as the antennas of the series arrays of discrete Josephson junctions, we demonstrate that the dielectric resonator antennas are more effective than microstrips.

Song, Fengbin; Müller, Franz; Behr, Ralf; Klushin, Alexander M.

2010-10-01

382

Resonant optical antennas.  

PubMed

We have fabricated nanometer-scale gold dipole antennas designed to be resonant at optical frequencies. On resonance, strong field enhancement in the antenna feed gap leads to white-light supercontinuum generation. The antenna length at resonance is considerably shorter than one-half the wavelength of the incident light. This is in contradiction to classical antenna theory but in qualitative accordance with computer simulations that take into account the finite metallic conductivity at optical frequencies. Because optical antennas link propagating radiation and confined/enhanced optical fields, they should find applications in optical characterization, manipulation of nanostructures, and optical information processing. PMID:15947182

Mühlschlegel, P; Eisler, H-J; Martin, O J F; Hecht, B; Pohl, D W

2005-06-10

383

Tunable multiwalled nanotube resonator  

DOEpatents

A tunable nanoscale resonator has potential applications in precise mass, force, position, and frequency measurement. One embodiment of this device consists of a specially prepared multiwalled carbon nanotube (MWNT) suspended between a metal electrode and a mobile, piezoelectrically controlled contact. By harnessing a unique telescoping ability of MWNTs, one may controllably slide an inner nanotube core from its outer nanotube casing, effectively changing its length and thereby changing the tuning of its resonance frequency. Resonant energy transfer may be used with a nanoresonator to detect molecules at a specific target oscillation frequency, without the use of a chemical label, to provide label-free chemical species detection.

Jensen, Kenneth J; Girit, Caglar O; Mickelson, William E; Zettl, Alexander K; Grossman, Jeffrey C

2013-11-05

384

Tunable multiwalled nanotube resonator  

DOEpatents

A tunable nanoscale resonator has potential applications in precise mass, force, position, and frequency measurement. One embodiment of this device consists of a specially prepared multiwalled carbon nanotube (MWNT) suspended between a metal electrode and a mobile, piezoelectrically controlled contact. By harnessing a unique telescoping ability of MWNTs, one may controllably slide an inner nanotube core from its outer nanotube casing, effectively changing its length and thereby changing the tuning of its resonance frequency. Resonant energy transfer may be used with a nanoresonator to detect molecules at a specific target oscillation frequency, without the use of a chemical label, to provide label-free chemical species detection.

Zettl, Alex K. (Kensington, CA); Jensen, Kenneth J. (Berkeley, CA); Girit, Caglar (Albany, CA); Mickelson, William E. (San Francisco, CA); Grossman, Jeffrey C. (Berkeley, CA)

2011-03-29

385

Strongly driven electron spins using a K(u) band stripline electron paramagnetic resonance resonator.  

PubMed

This article details our work to obtain strong excitation for electron paramagnetic resonance (EPR) experiments by improving the resonator's efficiency. The advantages and application of strong excitation are discussed. Two 17 GHz transmission-type, stripline resonators were designed, simulated and fabricated. Scattering parameter measurements were carried out and quality factor were measured to be around 160 and 85. Simulation results of the microwave's magnetic field distribution are also presented. To determine the excitation field at the sample, nutation experiments were carried out and power dependence were measured using two organic samples at room temperature. The highest recorded Rabi frequency was rated at 210 MHz with an input power of about 1 W, which corresponds to a ?/2 pulse of about 1.2 ns. PMID:23703225

Yap, Yung Szen; Yamamoto, Hiroshi; Tabuchi, Yutaka; Negoro, Makoto; Kagawa, Akinori; Kitagawa, Masahiro

2013-07-01

386

QUASI-RESONANT THEORY OF TIDAL INTERACTIONS  

SciTech Connect

When a spinning system experiences a transient gravitational encounter with an external perturber, a quasi-resonance occurs if the spin frequency of the victim roughly matches the peak angular speed of the perturber. Such encounters are responsible for the formation of long tails and bridges during galaxy collisions. For high-speed encounters, the resulting velocity perturbations can be described by the impulse approximation. The traditional impulse approximation, however, does not distinguish between prograde and retrograde encounters, and therefore completely misses the resonant response. Here, we modify the impulse approximation to include the effects of quasi-resonant phenomena on stars orbiting within a disk. Explicit expressions are derived for the velocity and energy changes to the stars induced by tidal forces from an external gravitational perturber passing either on a straight line or a parabolic orbit. Comparisons with numerical-restricted three-body calculations illustrate the applicability of our analysis.

D'Onghia, Elena; Vogelsberger, Mark; Faucher-Giguere, Claude-Andre; Hernquist, Lars, E-mail: edonghia@cfa.harvard.ed [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2010-12-10

387

Silicon optomechanical crystal resonator at millikelvin temperatures  

NASA Astrophysics Data System (ADS)

Optical measurements of a nanoscale silicon optomechanical crystal cavity with a mechanical resonance frequency of 3.6 GHz are performed at subkelvin temperatures. We infer optical-absorption-induced heating and damping of the mechanical resonator from measurements of phonon occupancy and motional sideband asymmetry. At the lowest probe power and lowest fridge temperature (Tf=10 mK), the localized mechanical resonance is found to couple at a rate of ?i/2?=400 Hz (Qm=9×106) to a thermal bath of temperature Tb?270 mK. These measurements indicate that silicon optomechanical crystals cooled to millikelvin temperatures should be suitable for a variety of experiments involving coherent coupling between photons and phonons at the single quanta level.

Meenehan, Seán M.; Cohen, Justin D.; Gröblacher, Simon; Hill, Jeff T.; Safavi-Naeini, Amir H.; Aspelmeyer, Markus; Painter, Oskar

2014-07-01

388

Astatine and Yttrium Resonant Ionization Laser Spectroscopy  

NASA Astrophysics Data System (ADS)

Providing intense, contamination-free beams of rare isotopes to experiments is a challenging task. At isotope separator on-line facilities such as ISAC at TRIUMF, the choice of production target and ion source are key to the successful beam delivery. Due to their element-selectivity, high efficiency and versatility, resonant ionization laser ion sources (RILIS) gain increasingly in importance. The spectroscopic data available are typically incomplete in the region of excited- and autoionizing atomic states. In order to find the most efficient ionization scheme for a particular element, further spectroscopy is often required. The development of efficient laser resonant ionization schemes for yttrium and astatine is presented in this thesis. For yttrium, two ionization schemes with comparable relative intensities were found. Since for astatine, only two transitions were known, the focus was to provide data on atomic energy levels using resonance ionization spectroscopy. Altogether 41 previously unknown astatine energy levels were found.

Teigelhoefer, Andrea

389

Effect of Angular Velocity on Sensors Based on Morphology Dependent Resonances  

PubMed Central

We carried out an analysis to investigate the morphology dependent optical resonances shift (MDR) of a rotating spherical resonator. The spinning resonator experiences an elastic deformation due to the centrifugal force acting on it, leading to a shift in its MDR. Experiments are also carried out to demonstrate the MDR shifts of a spinning polydimethylsiloxane (PDMS) microsphere. The experimental results agree well with the analytical prediction. These studies demonstrated that spinning sensor based on MDR may experience sufficient shift in the optical resonances, therefore interfering with its desirable operational sensor design. Also the results show that angular velocity sensors could be designed using this principle. PMID:24759108

Ali, Amir R.; Ioppolo, Tindaro

2014-01-01

390

Resonances in Positronium Hydride  

NASA Technical Reports Server (NTRS)

We re-examine the problem of calculating the positions and widths of the lowest-lying resonances in the Ps + H scattering system which consists of two electrons, one positron and one proton. The first of these resonances, for L=0, was found by the methods of complex rotation and stabilization, and later described as a Feshbach resonance lying close to a bound state in the closed-channel e (+) + H (-) system. Recently, results for the L=1 and 2 scattering states were published, and it was found, surprisingly, that there is a larae shift in the positions of these resonances. In this work we repeat the analysis for L=1 and find an unexpected explanation for the shift.

DiRienzi, Joseph; Drachman, Richard J.; Fisher, Richard R. (Technical Monitor)

2001-01-01

391

Validating resonance properties using nuclear resonance fluorescence  

NASA Astrophysics Data System (ADS)

Measurement of a resonance's integrated cross section using nuclear resonance fluorescence can be a valuable tool for verifying the properties of the resonance because of the clear and unambiguous physical connection to the spin, lifetime, and ground state branching ratio of the level. We demonstrate this idea by measuring the integrated cross section of the 3.004-MeV level in 27Al to 4% using the monoenergetic ? -ray beam at the High Intensity ? -ray Source. That level was the subject of much debate experimentally in the 1960s, especially its spin, and even now only has a current tentative spin assignment of J =(9 /2 ) . The consistency check between this integrated cross section and the known properties of the level indicate that one (or more) of the literature properties is incorrect. Based on the range of extent of each property, a reassignment of spin to a tentative J =(7 /2 ) may be warranted, but this would need to be confirmed with other measurements. This result demonstrates the utility of NRF as a way to verify the properties of states in the literature before undertaking more extensive measurements.

Angell, C. T.; Hajima, R.; Hayakawa, T.; Shizuma, T.; Karwowski, H. J.; Silano, J.

2014-11-01

392

Hexagonal quartz resonator  

DOEpatents

A generally flat, relatively thin AT-cut piezoelectric resonator element structured to minimize the force-frequency effect when mounted and energized in a housing. The resonator is in the form of an equilateral hexagon with the X crystallographic axis of the crystal passing through one set of opposing corners with mounting being effected at an adjacent set of corners respectively .+-.60.degree. away from the X axis which thereby results in a substantially zero frequency shift of the operating frequency.

Peters, Roswell D. M. (Rustburg, VA)

1982-01-01

393

Injector with integrated resonator  

DOEpatents

The system may include a turbine engine. The turbine engine may include a fuel nozzle. The fuel nozzle may include an air path. The fuel nozzle may also include a fuel path such that the fuel nozzle is in communication with a combustion zone of the turbine engine. Furthermore, the fuel nozzle may include a resonator. The resonator may be disposed in the fuel nozzle directly adjacent to the combustion zone.

Johnson, Thomas Edward; Ziminsky, Willy Steve; York, William David; Stevenson, Christian Xavier

2014-07-29

394

Nuclear magnetic resonance gyroscope  

SciTech Connect

A nuclear magnetic resonance gyro using two nuclear magnetic resonance gases, preferably xenon 129 and xenon 131, together with two alkaline metal vapors, preferably rubidium, potassium or cesium, one of the two alkaline metal vapors being pumped by light which has the wavelength of that alkaline metal vapor, and the other alkaline vapor being illuminated by light which has the wavelength of that other alkaline vapor.

Grover, B.C.

1984-02-07

395

Luminescence resonance energy transfer  

Microsoft Academic Search

Fluorescence resonance energy transfer (FRET), in which a fluorescent donor molecule transfers energy via a nonradiative dipole-dipole interaction to an acceptor molecule (which is usually a fluorescent molecule), is a standard spectroscopic technique for measuring distances in the 10-70 Angstrom range. We have used a luminescent europium chelate as donor and an organic dye, CY-5, as acceptor. This luminescence resonance

Paul R. Selvin; Tariq M. Rana; John E. Hearst

1994-01-01

396

Resonant dielectric metamaterials  

DOEpatents

A resonant dielectric metamaterial comprises a first and a second set of dielectric scattering particles (e.g., spheres) having different permittivities arranged in a cubic array. The array can be an ordered or randomized array of particles. The resonant dielectric metamaterials are low-loss 3D isotropic materials with negative permittivity and permeability. Such isotropic double negative materials offer polarization and direction independent electromagnetic wave propagation.

Loui, Hung; Carroll, James; Clem, Paul G; Sinclair, Michael B

2014-12-02

397

Eigenproblems in Resonant MEMS Design  

E-print Network

Eigenproblems in Resonant MEMS Design David Bindel UC Berkeley, CS Division Eigenproblems inResonant MEMS Design ­ p.1/21 #12;What are MEMS? Eigenproblems inResonant MEMS Design ­ p.2/21 #12;RF MEMS Microguitars from Cornell University (1997 and 2003) MHz-GHz mechanical resonators Uses: RF signal processing

Bai, Zhaojun

398

Resonant Quadrupole Peter Cameron -BNL  

E-print Network

Resonant Quadrupole Monitor Peter Cameron - BNL #12;LARP Workshop at FNAL6/9/2003 2 Resonant BPM · M. Kesselman et al - PAC 2001 · Stub-tuned 1/4 wave resonator · Simulated in Spice · frequency ~ 240MHz (8.5xRF) · Qloaded ~ 100 optimal coupling · In-tunnel hybrid for and · Resonate difference mode

Large Hadron Collider Program

399

Characteristics of fluid-induced resonances observed during microseismic monitoring  

NASA Astrophysics Data System (ADS)

Three groups of resonances are observed during a two-stage hydraulic experiment recorded by 12 three-component geophones. The injected fluid is composed of a slurry of mostly water and proppant plus some supercritical nitrogen. Resonance characteristics are estimated using an autoregressive model. Three resonance models are investigated: fluid-filled cracks, nonlaminar fluid flow, and repetitive events in terms of anticipated resonance frequencies, quality factors, and amplitudes. The observed resonances are very stable and positively correlated with either the slurry flow or the nitrogen injection rate, which is in contradiction with the repetitive events and fluid-filled crack models, respectively. Resonances obtained by numerical simulations of an unstable jet agree with the main characteristics of most observed resonances. Our observations suggest that variations in resonance frequencies are mainly driven by variations in fluid flow, whereas quality factors are more sensitive to the fluid composition through variations in nitrogen injection rate. This study also suggests that resonance frequencies and quality factors can provide complementary information for real-time monitoring of fluid injection into reservoirs, for hydraulic stimulations, geothermal operations, carbon capture, and storage or fluid movement during volcano eruptions.

Tary, Jean Baptiste; Baan, Mirko; Sutherland, Bruce; Eaton, David W.

2014-11-01

400

A novel five-category multimodal T1-weighted and T2-weighted magnetic resonance imaging-based stratification system for the selection of spinal arachnoid cyst treatment: a 15-year experience of 81 cases  

PubMed Central

Background Idiopathic spinal arachnoid cysts are rare cystic masses of the spinal canal generally classified as intra- or extradural, based on anatomical presentation. However, this system may not effectively indicate treatment. Objective To investigate the incidence, resection modality, and prognosis of spinal arachnoid cyst in a 15-year case series. Patients and methods A retrospective study was conducted in 81 spinal arachnoid cyst patients (male:female 34:47, mean age 36.5 years, age range 6–66 years) classified using a novel five-category T1-weighted and T2-weighted magnetic resonance imaging (MRI) classification system (intramedullary, subdural extramedullary, subdural/epidural, intraspinal epidural, or intraspinal/extraspinal). Conservative treatment failed in all patients. They underwent spinal surgery between January 1995 and December 2010 and were followed up for 69 (range 3–187) months. Performance outcomes were assessed using the Fugl-Meyer (FM) scale 90 days after operation. Recurrences and deaths were recorded. Results Subdural/epidural and intraspinal epidural cysts accounted for 66.7% (54 of 81) of patients, but exhibited relatively lower rates of postsurgical improvement using FM, with only 66.7% (36 of 54) of patients showing improvements. Excellent outcomes using the FM scale were reached in 100% (eight of eight) of intramedullary, intraspinal/extraspinal, and subdural extramedullary cyst patients, 86.7% (13 of 15) of subdural extramedullary cyst patients, and 66.7% (36 of 54) of epidural intraspinal cyst patients. Conclusion The proposed five-category multimodal MRI-based stratification system for spinal arachnoid cyst patients may more effectively allow clinicians to select the appropriate surgical intervention, and may help to predict outcomes. PMID:24672241

Qi, Ji; Yang, Jun; Wang, Guihuai

2014-01-01

401

Using Nuclear Magnetic Resonance Spectroscopy for Measuring Ternary Phase Diagrams  

ERIC Educational Resources Information Center

A laboratory experiment is presented for the upper-level undergraduate physical chemistry curriculum in which the ternary phase diagram of water, 1-propanol and n-heptane is measured using proton nuclear magnetic resonance (NMR) spectroscopy. The experiment builds upon basic concepts of NMR spectral analysis, typically taught in the undergraduate…

Woodworth, Jennifer K.; Terrance, Jacob C.; Hoffmann, Markus M.

2006-01-01

402

Progress towards understanding baryon resonances  

SciTech Connect

The composite nature of baryons manifests itself in the existence of a rich spectrum of excited states, in particular in the important mass region 1?2 GeV for the light-flavoured baryons. The properties of these resonances can be identified by systematic investigations using electromagnetic and strong probes, primarily with beams of electrons, photons, and pions. After decades of research, the fundamental degrees of freedom underlying the baryon excitation spectrum are still poorly understood. The search for hitherto undiscovered but predicted resonances continues at many laboratories around the world. Recent results from photo- and electroproduction experiments provide intriguing indications for new states and shed light on the structure of some of the known nucleon excitations. The continuing study of available data sets with consideration of new observables and improved analysis tools have also called into question some of the earlier findings in baryon spectroscopy. Other breakthrough measurements have been performed in the heavy-baryon sector, which has seen a fruitful period in recent years, in particular at the B factories and the Tevatron. First results from the large hadron collider indicate rapid progress in the field of bottom baryons. In this review, we discuss the recent experimental progress and give an overview of theoretical approaches.

Crede, Volker [FSU; Roberts, Winston [FSU

2013-07-01

403

Gravitational Wave Generation and Detection Using Acoustic Resonators and Coupled Resonance Chambers  

NASA Astrophysics Data System (ADS)

An experiment is described for the generation and detection of High-Frequency Gravitational Waves (HFGWs) in the laboratory utilizing acoustic piezoelectric resonators for generation, and coupled resonance chambers for detection. Film Bulk Acoustic Resonators or FBARs (similar to those utilized in commercial cellular telephones) energized by magnetrons (similar to those utilized in microwave ovens) are distributed in a ring-shaped array several hundred meters in diameter. The magnetrons are phase locked and are sufficient in number to energize millions of FBARs fabricated on thousands of wafers. The FBARs produce jerks (time rate of change of acceleration or a third time derivative motion imparted to their electrode masses) at a frequency of 2.45GHz. The resulting 4.9GHz HFGW is focused at the center of a segmented or asymmetrical ring of FBARs and is concentrated there by a high-temperature superconductor (HTSC) to generate a HFGW flux on the order of 17mW m-2 to 7W m-2. A miniature version of an existing HFGW detector designed at INFN Genoa, Italy, consisting of a pair of coupled HTSC-surfaced resonance chambers (about one centimeter in diameter) will be situated in the middle, having their axes perpendicular to the plane of the ring of FBARs. Alternatively, a resonance-loop chamber detector, similar to that developed at Birmingham University, U.K., could be utilized. Details of the experiment and challenges to be met in its design as well as applications to space technology are discussed.

Woods, R. Clive; Baker, Robert M. L.

2005-02-01

404

Tunable Resonant Scanners  

NASA Astrophysics Data System (ADS)

The most attractive features of resonant scanners are high reliability and eternal life as well as extremely low wobble and jitter. Power consumption is also low, electronic drive is simple, and the device is capable of handling large beams. All of these features are delivered at a low cost in a small package. The resonant scanner's use in numerous high precision applications, however, has been limited because of the difficulty in controlling its phase and resonant frequency. This paper introduces the concept of tunable/controllable resonant scanners, discusses their features, and offers a number of tuning techniques. It describes two angular scanner designs and presents data on tunable range and life tests. It also reviews applications for these new tunable resonant scanners that preserve the desirable features of earlier models while removing the old problems with synchronization or time base flexibility. The three major types of raster scanning applications where the tunable resonant scanner may be of benefit are: 1. In systems with multiple time bases such as multiple scanner networks or with scanners keyed to a common clock (the line frequency or data source) or a machine with multiple resonant scanners. A typical application is image and text transmission, also a printer with a large data base where a buffer is uneconomical. 2. In systems sharing data processing or laser equipment for reasons of cost or capacity, typically multiple work station manufacturing processes or graphic processes. 3. In systems with extremely precise time bases where the frequency stability of conventional scanners cannot be relied upon.

Montagu, Jean I.

1987-01-01

405

Stochastic Resonance In Visual Perception  

NASA Astrophysics Data System (ADS)

Stochastic resonance (SR) is a well established physical phenomenon wherein some measure of the coherence of a weak signal can be optimized by random fluctuations, or "noise" (K. Wiesenfeld and F. Moss, Nature), 373, 33 (1995). In all experiments to date the coherence has been measured using numerical analysis of the data, for example, signal-to-noise ratios obtained from power spectra. But, can this analysis be replaced by a perceptive task? Previously we had demonstrated this possibility with a numerical model of perceptual bistability applied to the interpretation of ambiguous figures(M. Riani and E. Simonotto, Phys. Rev. Lett.), 72, 3120 (1994). Here I describe an experiment wherein SR is detected in visual perception. A recognizible grayscale photograph was digitized and presented. The picture was then placed beneath a threshold. Every pixel for which the grayscale exceeded the threshold was painted white, and all others black. For large enough threshold, the picture is unrecognizable, but the addition of a random number to every pixel renders it interpretable(C. Seife and M. Roberts, The Economist), 336, 59, July 29 (1995). However the addition of dynamical noise to the pixels much enhances an observer's ability to interpret the picture. Here I report the results of psychophysics experiments wherein the effects of both the intensity of the noise and its correlation time were studied.

Simonotto, Enrico

1996-03-01

406

Nonlinear dynamics experiments  

SciTech Connect

The goal of nonlinear dynamics experiments is to improve the understanding of single particle effects that increase the particle amplitude and lead to loss. Particle motion in storage rings is nearly conservative and for transverse dynamics the Hamiltonian in action angle variables (I{sub x},I{sub y},{phi}{sub x},{phi}{sub y}) near an isolated resonance k{nu}{sub x} + l{nu}{sub y} {approx} p is H = I{sub x}{nu}{sub x0} + I{sub y}{nu}{sub y0} + g(I{sub x}, I{sub y}) + h(I{sub x}, I{sub y})cos(k{phi}{sub x} + l{phi}{sub y} - p{theta}), (1) where k, l, p are integers, {theta} = 2{pi}s/L is the azimuth, and s and L are the path length and circumference respectively. The amplitude dependent tunes are given by {nu}{sub x,y}(I{sub x},I{sub y}) = {nu}{sub x0,y0} + {partial_derivative}g(I{sub x},I{sub y})/{partial_derivative}I{sub x,y} (2) and h(I{sub x},I{sub y}) is the resonance driving term (RDT). If the motion is governed by multiple resonances, h(I{sub x},I{sub y}) has to be replace by a series of terms. The particle motion is completely determined by the terms g and h, which can be calculated from higher order multipoles (Sec. ??), or obtained from simulations. Deviations from pure Hamiltonian motion occur due to synchrotron radiation damping (Sec. ??) in lepton or very high energy hadron rings, parameter variations, and diffusion processes such as residual gas and intrabeam scattering. The time scale of the non-Hamiltonian process determines the applicability of the Hamiltonian analysis. Transverse nonlinearities are introduced through sextupoles or higher order multipoles and magnetic field errors in dipoles and quadrupoles. Sextupoles can already drive all resonances. The beam-beam interaction and space charge also introduce nonlinear fields. Intentionally introduced nonlinearities are used to extract beam on a resonance or through capture in stable islands. Localization and minimization of nonlinearities in a ring is a general strategy to decrease emittance growth and increase the beam lifetime. The minimization of nonlinear effects can be done locally or globally. Except for resonant extraction, amplitude increase and particle loss is the result of chaotic particle motion. Large chaotic regions allow particles to increase their amplitudes, and ensures their ultimate loss. However, chaotic particles can, on average, still survive the time period of interest, i.e. the storage time. Nonlinear dynamics experiments aim to determine either the detuning and driving terms g and h directly, or their effect on other quantities. Nonlinear phenomena observed in experiments include phase space deformations and resonant islands in Poincare surfaces of section, nonlinear phase advances, amplitude detuning g, decoherence (Sec. ??), resonance driving terms h, smear, halo formation, echoes (Sec. ??), the tune response matrix, dynamic aperture (Sec. ??), emittance growth, and particle loss. Nonlinear experiments can also be done in the longitudinal plane.

Fischer, W.

2011-01-01

407

Resonant Switching Using Spin Valves  

NASA Astrophysics Data System (ADS)

Using micromagnetics we demonstrate that the r.f. field produced by a spin valve can be used to reverse the magnetization in a magnetic nanoparticle. The r.f. field is generated using a current that specifically excites a uniform spin wave in the spin valve. This current is swept such that the chirped-frequency generated by the valve matches the angular dependent resonant frequency of the anisotropy-dominated magnetic nanoparticle, as a result of which the magnetization reversal occurs. The switching is fast, requires currents similar to those used in recent experiments with spin valves, and is stable with respect to small perturbations. This phenomenon can potentially be employed in magnetic information storage devices or recently discussed magnetic computing schemes.

Rivkin, K.; Ketterson, J. B.; Saslow, W.

2007-06-01

408

Diamagnetic phase transition by helicon resonance  

NASA Astrophysics Data System (ADS)

The onset of the diamagnetic phase transition in aluminum is shown by analyzing the temperature dependence of the helicon resonance frequency and damping and by comparing between the theory and the experiment. Softening of the helicon mode due to the domain appearance is calculated. The critical growth of the helicon damping is connected with the phase transition nature of the domain occurrence, i.e. with the critical dynamics of diamagnetic phase transitions related to critical slowing down of the electron relaxation time.

Gordon, A.; Joss, W.; Logoboy, N.; Vagner, I. D.

2003-09-01

409

Paramagnetic Resonance Hyperfine Structure of Co56  

Microsoft Academic Search

The microwave paramagnetic resonance hyperfine structure of 72-day Co56 has been observed in a magnetically dilute single crystal of cobalt potassium sulfate at 20°K. From the number of hfs components and their spacing relative to Co59, the spin I(Co56)=4 and the magnetic moment |mu(Co56)|=3.855+\\/-0.007 nm are directly determined. These results are discussed in relation to those of nuclear alignment experiments

R. V. Jones; W. Dobrowolski; C. D. Jeffries

1956-01-01

410

Frequency shifts in gravitational resonance spectroscopy  

E-print Network

Quantum states of ultracold neutrons in the gravitational field are to be characterized through gravitational resonance spectroscopy. This paper discusses systematic effects that appear in the spectroscopic measurements. The discussed frequency shifts, which we call Stern-Gerlach shift, interference shift, and spectator state shift, appear in conceivable measurement schemes and have general importance. These shifts have to be taken into account in precision experiments.

S. Baeßler; V. V. Nesvizhevsky; G. Pignol; K. V. Protasov; D. Rebreyend; E. A. Kupriyanova; A. Yu. Voronin

2015-01-13

411

Frequency shifts in gravitational resonance spectroscopy  

E-print Network

Quantum states of ultracold neutrons in the gravitational field are to be characterized through gravitational resonance spectroscopy. This paper discusses systematic effects that appear in the spectroscopic measurements. The discussed frequency shifts, which we call Stern-Gerlach shift, interference shift, and spectator state shift, appear in conceivable measurement schemes and have general importance. These shifts have to be taken into account in precision experiments.

Baeßler, S; Pignol, G; Protasov, K V; Rebreyend, D; Kupriyanova, E A; Voronin, A Yu

2015-01-01

412

Resonant ultrasound spectrometer  

DOEpatents

An ultrasound resonant spectrometer determines the resonant frequency spectrum of a rectangular parallelepiped sample of a high dissipation material over an expected resonant response frequency range. A sample holder structure grips corners of the sample between piezoelectric drive and receive transducers. Each transducer is mounted on a membrane for only weakly coupling the transducer to the holder structure and operatively contacts a material effective to remove system resonant responses at the transducer from the expected response range. i.e., either a material such as diamond to move the response frequencies above the range or a damping powder to preclude response within the range. A square-law detector amplifier receives the response signal and retransmits the signal on an isolated shield of connecting cabling to remove cabling capacitive effects. The amplifier also provides a substantially frequency independently voltage divider with the receive transducer. The spectrometer is extremely sensitive to enable low amplitude resonance to be detected for use in calculating the elastic constants of the high dissipation sample.

Migliori, Albert (Santa Fe, NM); Visscher, William M. (Los Alamos, NM); Fisk, Zachary (Santa Fe, NM)

1990-01-01

413

MACHINERY RESONANCE AND DRILLING  

SciTech Connect

New developments in vibration analysis better explain machinery resonance, through an example of drill bit chattering during machining of rusted steel. The vibration of an operating drill motor was measured, the natural frequency of an attached spring was measured, and the two frequencies were compared to show that the system was resonant. For resonance to occur, one of the natural frequencies of a structural component must be excited by a cyclic force of the same frequency. In this case, the frequency of drill bit chattering due to motor rotation equaled the spring frequency (cycles per second), and the system was unstable. A soft rust coating on the steel to be drilled permitted chattering to start at the drill bit tip, and the bit oscillated on and off of the surface, which increased the wear rate of the drill bit. This resonant condition is typically referred to as a motor critical speed. The analysis presented here quantifies the vibration associated with this particular critical speed problem, using novel techniques to describe resonance.

Leishear, R.; Fowley, M.

2010-01-23

414

Image restoration using fast Fourier and wavelet transforms  

NASA Astrophysics Data System (ADS)

Pure nuclear quadrupole resonance (NQR) of 14N nuclei is quite promising as a method for detecting explosives such as RDX and contraband narcotics such as cocaine and heroin in quantities of interest. Pure NQR is conducted without an external applied magnetic field, so potential concerns about damage to magnetically encoded data or exposure of personnel to large magnetic fields are not relevant. Because NQR frequencies of different compounds are quite distinct, we do not encounter false alarms from the NQR signals of other benign materials. We have constructed a proof-of-concept NQR explosives detector which interrogates a volume of 300 liters (10 ft3). With minimal modification to the existing explosives detector, we can detect operationally relevant quantities of (free base) cocaine within the 300-liter inspection volume in 6 seconds. We are presently extending this approach to the detection of heroin base and also examining 14N and 35,37Cl pure NQR for detection of the hydrochloride forms of both materials. An adaptation of this NQR approach may be suitable for scanning personnel for externally carried contraband and explosives. We first outline the basics of the NQR approach, highlighting strengths and weaknesses, and then present representative results for RDX and cocaine detection. We also present a partial compendium of relevant NQR parameters measured for some materials of interest.

Harrod, William J.; Nagy, James G.; Plemmons, Robert J.

1994-02-01

415

Control of Cavity Resonance Using Steady and Oscillatory Blowing  

NASA Technical Reports Server (NTRS)

An experimental study to investigate the effect of steady and oscillatory (with zero net mass flux) blowing on cavity resonance is undertaken. The objective is to study the basic mechanisms of the control of cavity resonance. An actuator is designed and calibrated to generate either steady blowing or oscillatory blowing with A zero net mass flux. The results of the experiment show that both steady and oscillatory blowing are effective, and reduce the amplitude of the dominant resonant mode by 1OdB. The oscillatory blowing is however found to be more superior in that the same effectiveness could be accomplished with a momentum coefficient an order of magnitude smaller than for steady blowing. The experiment also confirms the results of previous computations that suggest the forcing frequency for oscillatory blowing must not be at harmonic frequencies of the cavity resonant modes.

Lamp, Alison M.; Chokani, Ndaona

1999-01-01

416

Fiber Bragg grating cladding mode resonance liquid-level sensor  

NASA Astrophysics Data System (ADS)

A Fiber-optic liquid-level sensor based on etched fiber Bragg grating (FBG) cladding mode resonance is proposed and demonstrated both theoretically and experimentally. The theoretical model of the FBG cladding mode liquid-level sensor is built under a three-layer step-index fiber geometry. Response of cladding mode resonance spectra to the variation of ambient liquid level are studied and simulated numerically with couple mode theory and transmission matrix method. In the experiments, a chemical etching method is adopted to diminish the fiber cladding diameter and increase the sensitivity of cladding mode resonances to the ambient refractive index change. Dependences of FBG cladding mode resonance spectra on the liquid-level variation are measured and the experiments data match the model well.

Chen, Na; Yun, Binfeng; Cui, Yiping

2009-10-01

417

Magnetic Resonance Online Texts  

NSDL National Science Digital Library

This well-organized and very thorough website was developed by the physicist Stanislav Sykora with the aim of providing free online texts, theses, and course materials on the subjects of magnetic resonance (MR), magnetic resonance imaging (MRI), nuclear-magnetic resonance (NMR) and other related topics. The amount of material on the site is impressive. At the top of the page are links to an "MR Blog", as well as to "MR Links" and the "Site Plan & SEARCH". The NMR/MRI Extras section on the right side of the page is particularly useful for visitors interested in all things about MR. Its links to "Events" provides an up-to-date list of symposia, conferences, and meetings, along with links to the events' sites. The "Societies" link offers at least 50 groups about MR, some of which are country-based, and others that are region- or application-based.

S�½kora, Stanislav

418

Magnetostrictive resonance excitation  

DOEpatents

The resonance frequency spectrum of a magnetostrictive sample is remotely determined by exciting the magnetostrictive property with an oscillating magnetic field. The permeability of a magnetostrictive material and concomitant coupling with a detection coil varies with the strain in the material whereby resonance responses of the sample can be readily detected. A suitable sample may be a magnetostrictive material or some other material having at least one side coated with a magnetostrictive material. When the sample is a suitable shape, i.e., a cube, rectangular parallelepiped, solid sphere or spherical shell, the elastic moduli or the material can be analytically determined from the measured resonance frequency spectrum. No mechanical transducers are required and the sample excitation is obtained without contact with the sample, leading to highly reproducible results and a measurement capability over a wide temperature range, e.g. from liquid nitrogen temperature to the Curie temperature of the magnetostrictive material.

Schwarz, Ricardo B. (Los Alamos, NM); Kuokkala, Veli-Tapani (Tampere, FI)

1992-01-01

419

Double Entropic Stochastic Resonance  

E-print Network

We demonstrate the appearance of a purely entropic stochastic resonance (ESR) occurring in a geometrically confined system, where the irregular boundaries cause entropic barriers. The interplay between a periodic input signal, a constant bias and intrinsic thermal noise leads to a resonant ESR-phenomenon in which feeble signals become amplified. This new phenomenon is characterized by the presence of two peaks in the spectral amplification at corresponding optimal values of the noise strength. The main peak is associated with the manifest stochastic resonance synchronization mechanism involving the inter-well noise-activated dynamics while a second peak relates to a regime of optimal sensitivity for intra-well dynamics. The nature of ESR, occurring when the origin of the barrier is entropic rather than energetic, offers new perspectives for novel investigations and potential applications. ESR by itself presents yet another case where one constructively can harvest noise in driven nonequilibrium systems.

P. S. Burada; G. Schmid; D. Reguera; J. M. Rubi; P. Hänggi

2009-08-24

420

Superdimensional Metamaterial Resonators  

E-print Network

We propose a fundamentally new method for the design of metamaterial arrays, valid for any waves modeled by the Helmholtz equation, including scalar optics and acoustics. The design and analysis of these devices is based on eigenvalue and eigenfunction asymptotics of solutions to Schr\\"odinger wave equations with harmonic and degenerate potentials. These resonators behave superdimensionally, with a higher local density of eigenvalues and greater concentration of waves than expected from the physical dimension, e.g., planar resonators function as 3- or higher-dimensional media, and bulk material as effectively of dimension 4 or higher. Applications include antennas with a high density of resonant frequencies and giant focussing, and are potentially broadband.

Greenleaf, Allan; Kurylev, Yaroslav; Lassas, Matti; Uhlmann, Gunther

2014-01-01

421

Quartz resonator processing system  

DOEpatents

Disclosed is a single chamber ultra-high vacuum processing system for the oduction of hermetically sealed quartz resonators wherein electrode metallization and sealing are carried out along with cleaning and bake-out without any air exposure between the processing steps. The system includes a common vacuum chamber in which is located a rotatable wheel-like member which is adapted to move a plurality of individual component sets of a flat pack resonator unit past discretely located processing stations in said chamber whereupon electrode deposition takes place followed by the placement of ceramic covers over a frame containing a resonator element and then to a sealing stage where a pair of hydraulic rams including heating elements effect a metallized bonding of the covers to the frame.

Peters, Roswell D. M. (Rustburg, VA)

1983-01-01

422

Mössbauer Resonance Studies of Ferrous Ions in Ice  

Microsoft Academic Search

Mo¨ssbauer resonance experiments have been carried out over a wide temperature range on frozen aqueous solutions of ferrous chloride and ferrous sulfate. Well-resolved spectra were obtained which show the two-line absorption pattern characteristic of a nuclear quadrupole hyperfine interaction in 57Fe. Measurements of quadrupole splitting, resonance linewidths, and anisotropic intensities were made as a function of temperature and for samples

Arthur J. Nozik; Morton Kaplan

1967-01-01

423

Topical applications of resonance internal conversion in laser produced plasma  

NASA Astrophysics Data System (ADS)

Physical aspects of resonance effects arising in plasma due to interactions of nuclei with the electrons are considered. Among them are resonance conversion (TEEN) and the reverse process of NEET. These processes are of great importance for pumping the excited nuclear states (isomers) and for accelerating their decay. Experiment is discussed on studying the unique 3.5-eV 229m Th nuclide.

Karpeshin, F. F.

2007-04-01

424

Physics of Sports: Resonances  

NASA Astrophysics Data System (ADS)

When force is applied by an athlete to sports equipment resonances can occur. Just a few examples are: the ringing of a spiked volleyball, the strumming of a golf club shaft during a swing, and multiple modes induced in an aluminum baseball bat when striking a ball. Resonances produce acoustic waves which, if conditions are favorable, can be detected off the playing field. This can provide a means to evaluate athletic performance during game conditions. Results are given from the use of a simple hand-held acoustic detector - by a spectator sitting in the stands - to determine how hard volleyballs were spiked during college and high school games.

Browning, David

2000-04-01

425

Pygmy resonances and nucleosynthesis  

E-print Network

A microscopic theoretical approach based on a self-consistent density functional theory for the nuclear ground state and QRPA formalism extended with multi-phonon degrees of freedom for the nuclear excited states is implemented in investigations of new low-energy modes called pygmy resonances. Advantage of the method is the unified description of low-energy multiphonon excitations, pygmy resonances and core polarization effects. This is found of crucial importance for the understanding of the fine structure of nuclear response functions at low energies. Aspects of the precise knowledge of nuclear response functions around the neutron threshold are discussed in a connection to nucleosynthesis.

Tsoneva, Nadia

2014-01-01

426

Pygmy resonances and nucleosynthesis  

E-print Network

A microscopic theoretical approach based on a self-consistent density functional theory for the nuclear ground state and QRPA formalism extended with multi-phonon degrees of freedom for the nuclear excited states is implemented in investigations of new low-energy modes called pygmy resonances. Advantage of the method is the unified description of low-energy multiphonon excitations, pygmy resonances and core polarization effects. This is found of crucial importance for the understanding of the fine structure of nuclear response functions at low energies. Aspects of the precise knowledge of nuclear response functions around the neutron threshold are discussed in a connection to nucleosynthesis.

Nadia Tsoneva; Horst Lenske

2014-10-09

427

Method for resonant measurement  

DOEpatents

A method of measurement of objects to determine object flaws, Poisson's ratio (.sigma.) and shear modulus (.mu.) is shown and described. First, the frequency for expected degenerate responses is determined for one or more input frequencies and then splitting of degenerate resonant modes are observed to identify the presence of flaws in the object. Poisson's ratio and the shear modulus can be determined by identification of resonances dependent only on the shear modulus, and then using that shear modulus to find Poisson's ratio using other modes dependent on both the shear modulus and Poisson's ratio.

Rhodes, George W. (5201 Rio Grande Blvd., N.W., Albuquerque, NM 87107); Migliori, Albert (Rte. 4, Box 258 Tano Rd., Sante Fe, NM 87501); Dixon, Raymond D. (396 Connie Ave., White Rock, NM 87544)

1996-01-01

428

Hexagonal quartz resonator  

DOEpatents

A generally flat, relatively thin AT-cut piezoelectric resonator element structured to minimize the force-frequency effect when mounted and energized in a housing. The resonator is in the form of an equilateral hexagon with the X crystallographic axis of the crystal passing through one set of opposing corners with mounting being effected at an adjacent set of corners respectively [+-]60[degree] away from the X axis which thereby results in a substantially zero frequency shift of the operating frequency. 3 figs.

Peters, R.D.M.

1982-11-02

429

Method for resonant measurement  

DOEpatents

A method of measurement of objects to determine object flaws, Poisson`s ratio ({sigma}) and shear modulus ({mu}) is shown and described. First, the frequency for expected degenerate responses is determined for one or more input frequencies and then splitting of degenerate resonant modes are observed to identify the presence of flaws in the object. Poisson`s ratio and the shear modulus can be determined by identification of resonances dependent only on the shear modulus, and then using that shear modulus to find Poisson`s ratio using other modes dependent on both the shear modulus and Poisson`s ratio. 1 fig.

Rhodes, G.W.; Migliori, A.; Dixon, R.D.

1996-03-05

430

Field resonance propulsion concept  

NASA Technical Reports Server (NTRS)

A propulsion concept was developed based on a proposed resonance between coherent, pulsed electromagnetic wave forms, and gravitational wave forms (or space-time metrics). Using this concept a spacecraft propulsion system potentially capable of galactic and intergalactic travel without prohibitive travel times was designed. The propulsion system utilizes recent research associated with magnetic field line merging, hydromagnetic wave effects, free-electron lasers, laser generation of megagauss fields, and special structural and containment metals. The research required to determine potential, field resonance characteristics and to evaluate various aspects of the spacecraft propulsion design is described.

Holt, A. C.

1979-01-01

431

Inexpensive Resonance Analysis  

NASA Astrophysics Data System (ADS)

A Barton's Pendulums device is a great tool for teaching students about resonance. Such a setup typically has several pendulums attached to a single string or solid support, where each pendulum is excited at a single frequency. The excitation can be produced by a large pendulum mass or by a motor. If a pendulum has a natural frequency that closely matches the excitation frequency, it swings with a large amplitude; otherwise, it does not. While these visual demonstrations are helpful, resonance behavior can be even better understood by graphically displaying the responses of oscillators to different excitations.

Moran, Timothy J.; Hill, Bradford K.

2009-12-01

432

Lorentz resonances and the structure of the Jovian ring  

NASA Technical Reports Server (NTRS)

Charged dust orbiting through spatially periodic planetary magnetic fields will experience time-variable electromagnetic forces. When the forcing frequencies are nearly commensurate with the particle's orbital frequency, the particle undergoes large out-of-plane and radial excursions. Specific 'Lorentz' resonances, corresponding to particular spatial periodicities in the magnetic field, occur on either side of synchronous orbit. Lorentz resonance locations and strengths for the Jovian and Saturnian rings are described. The boundaries of the halo of the Jovian ring, and perhaps other ring structures, are near resonances.

Burns, J. A.; Schaffer, L. E.; Showalter, M. R.; Greenberg, R. J.

1985-01-01

433

Quasi-fractional Talbot effect of resonant diffraction grating  

NASA Astrophysics Data System (ADS)

The Fresnel diffraction of resonant diffraction grating is studied on the basis of the modal method, and it shows that the conventional fractional Talbot effect can still occur by choosing appropriate parameters. The Fresnel diffraction distributions of the resonant diffraction gratings with periods between ? and 4? are analyzed, and the diffraction fields exhibit periodicity in both grating direction and the propagating direction. The experiment is carried out to verify the simulation results of the quasi-fractional Talbot effect of the resonant diffraction grating. This effect has potential application in lithography for high-resolution patterning.

Fang, Yue; Tan, Qiaofeng; Zhang, Mingqian; Jin, Guofan

2012-10-01

434

Compact pulley-type microring resonator with high quality factor  

NASA Astrophysics Data System (ADS)

A pulley-type microring resonator with ultra-small dimensions and ultra-high quality factor on a silicon-on-insulator wafer is fabricated and characterized. Simulation results show that the bending loss of the pulley-type microring resonator can be diminished by wrapping the curved waveguide around the microring, and that the energy loss from the output port can be decreased by tuning the width of the bus waveguide to achieve destructive interference. A quality factor of 1.73 × 105 is obtained in this experiment. The compact size of the pulley-type microring resonator with low bending loss is suitable for an integrated optical circuit.

Cai, Dong-Po; Lu, Jyun-Hong; Chen, Chii-Chang; Lee, Chien-Chieh; Lin, Chu-En; Yen, Ta-Jen

2014-11-01

435

Evaluation of stable tungsten isotopes in the resolved resonance region  

NASA Astrophysics Data System (ADS)

In the last decade benchmark experiments and simulations, together with newly obtained neutron cross section data, have pointed out deficiencies in evaluated data files of W isotopes. The role of W as a fundamental structural material in different nuclear applications fully justifies a new evaluation of 182, 183, 184, 186W neutron resonance parameters. In this regard transmission and capture cross section measurements on natural and enriched tungsten samples were performed at the GELINA facility of the EC-JRC-IRMM. A resonance parameter file used as input in the resonance shape analysis was prepared based on the available literature and adjusted in first instance to transmission data.

Emiliani, F.; Guber, K.; Kopecky, S.; Lampoudis, C.; Massimi, C.; Schillebeeckx, P.; Volev, K.

2013-03-01

436

Cyclotron resonance in II-VI semiconductors at THz region  

NASA Astrophysics Data System (ADS)

Cyclotron resonance experiments for various II-VI semiconductors (n-ZnO, n-ZnS, n-ZnSe, n-CdS, n-CdSe, n-CdTe) have been performed at ultra-high magnetic fields beyond 100 T. Cyclotron resonance and impurity related resonance are observed definitely with the use of THz radiation sources, and the magnetic field dependence of effective mass is obtained at a wide range of a THz region in n-type CdTe.

Imanaka, Y.; Takamasu, T.; Takehana, K.; Oshikiri, M.; Kido, G.; Nojiri, H.; Matsuda, Y. H.; Arimoto, H.; Takeyama, S.; Miura, N.; Karczewski, G.; Wojtowicz, T.; Kossut, J.

437

Nuclear magnetic and quadrupole resonance studies of local environments in magnetic and superconducting systems  

NASA Astrophysics Data System (ADS)

Spin-echo nuclear magnetic and quadrupole resonance (NMR/NQR) studies, along with complementary x-ray diffraction and bulk magnetization measurements, have been carried out on the magnetic superconducting system RuSr2RECu 2O8 (RE 1212, RE = Gd or Eu) and systems based on or derived from SrRuO3. In RE1212, two sets of Ru NMR signals are found, indicating the existence of a mixed valence for Ru. This result suggests a hole doping mechanism to account for the superconductivity that originates in the CuO2 planes. The evolution of the Ru NMR spectra in external magnetic fields provides information concerning the magnetic structure of the Ru sublattice which is consistent with the previously proposed type-I antiferromagnetic (AFM) structure. Based on this model, the interplane magnetic coupling and the in-plane spin-flop critical field are determined. While substituting for the Ru-site in SrRuO3, Mn and vacancies suppress the ferromagnetic (FM) ordering temperature drastically. Cr, on the other hand, increases the ordering temperature. The valence states for Mn, Cr, and Ru are determined from the NMR spectra, which, combined with dc magnetization, also provide information with regard to the various magnetic interactions. The hybridization of the Ru 4d and Mn or Cr 3d orbitals is believed to play a key role in the variation of the ordering temperature. Upon cooling, three consecutive and distinct magnetic transitions are observed for Sr2RuGdO6 at T1 = 33 K, T2 = 17, and T3 < 2 K which are attributed to the Ru-Ru, Ru-Gd, and Gd-Gd AFM interactions, respectively. Weak FM is associated with the transition at 17 K. These features point to the unique role played by Gd in this system. Ru NMR spectra, in the presence of an external magnetic field, demonstrate the existence of a FM phase in the AFM matrix which behaves superparamagnetically. These results strongly suggest that, at low temperature, the magnetic ground state of Sr2RuGdO6 involves complex coexistence and competition of different interactions.

Han, Zhaohui

2006-12-01

438

A Resonance Approach to Cochlear Mechanics  

PubMed Central

Background How does the cochlea analyse sound into its component frequencies? In the 1850s Helmholtz thought it occurred by resonance, whereas a century later Békésy's work indicated a travelling wave. The latter answer seemed to settle the question, but with the discovery in 1978 that the cochlea emits sound, the mechanics of the cochlea was back on the drawing board. Recent studies have raised questions about whether the travelling wave, as currently understood, is adequate to explain observations. Approach Applying basic resonance principles, this paper revisits the question. A graded bank of harmonic oscillators with cochlear-like frequencies and quality factors is simultaneously excited, and it is found that resonance gives rise to similar frequency responses, group delays, and travelling wave velocities as observed by experiment. The overall effect of the group delay gradient is to produce a decelerating wave of peak displacement moving from base to apex at characteristic travelling wave speeds. The extensive literature on chains of coupled oscillators is considered, and the occurrence of travelling waves, pseudowaves, phase plateaus, and forced resonance in such systems is noted. Conclusion and significance This alternative approach to cochlear mechanics shows that a travelling wave can simply arise as an apparently moving amplitude peak which passes along a bank of resonators without carrying energy. This highlights the possible role of the fast pressure wave and indicates how phase delays and group delays of a set of driven harmonic oscillators can generate an apparent travelling wave. It is possible to view the cochlea as a chain of globally forced coupled oscillators, and this model incorporates fundamental aspects of both the resonance and travelling wave theories. PMID:23144835

Bell, Andrew

2012-01-01

439

Systematic Study of the Pygmy Dipole Resonance  

NASA Astrophysics Data System (ADS)

In recent years, a systematic comparative study of the pygmy dipole resonance (PDR) using the (?,?') and the (?,?'?) reactions on the nuclei 140Ce, 138Ba, 124Sn, 94Mo, and 48Ca was performed. The aim of this systematic study is to explore the structure of the PDR by the usage of two complementary probes and several different nuclei. The real-photon scattering experiments were performed at the S-DALINAC in Darmstadt, Germany, while the (?, ?'?) coincidence experiments were performed at the Big-Bite Spectrometer (BBS) at KVI in Groningen, The Netherlands. The comparison of the results from both kinds of experiments showed an energetic splitting of the PDR into two parts that might be due to the different isospin character of these states. First experimental results of the (?, ?'?) experiments on the nuclei 94Mo and 48Ca will be presented.

Derya, V.; Endres, J.; Harakeh, M. N.; Savran, D.; Wörtche, H. J.; Zilges, A.

2012-05-01

440

Magnetic Resonance Imaging and Magnetic Resonance Spectroscopy in Dementias  

PubMed Central

This article reviews recent studies of magnetic resonance imaging and magnetic resonance spectroscopy in dementia, including Alzheimer's disease, frontotemporal dementia, dementia with Lewy bodies, idiopathic Parkinson's disease, Huntington's disease, and vascular dementia. Magnetic resonance imaging and magnetic resonance spectroscopy can detect structural alteration and biochemical abnormalities in the brain of demented subjects and may help in the differential diagnosis and early detection of affected individuals, monitoring disease progression, and evaluation of therapeutic effect. PMID:11563438

Hsu, Yuan-Yu; Du, An-Tao; Schuff, Norbert; Weiner, Michael W.

2007-01-01

441

Coherent control through near-resonant Raman transitions  

SciTech Connect

The phase of an electronic wave function is shown to play an important role in coherent control experiments. By using a pulse shaping system with a femtosecond laser, we explore the phase relationships among resonant and off-resonant Raman transitions in Li{sub 2} by measuring the phases of the resulting wave packets, or quantum beats. Specific pixels in a liquid-crystal spatial light modulator are used to isolate the resonant and off-resonant portions of the Raman transitions in Li{sub 2}. The off-resonant Raman transitions have an approximately 90 degree sign phase shift with respect to the resonant Raman transition, and there is an approximately 180 degree sign phase shift between the blue-detuned and the red-detuned off-resonant Raman transitions. Calculations using second-order time-dependent perturbation theory for the electronic transitions agree with the experimental results for the laser pulse intensities used here. Interferences between the off-resonant Raman transitions as a function of detuning are used to demonstrate coherent control of the Raman quantum wave packet.

Dai Xingcan; Lerch, Eliza-Beth W.; Leone, Stephen R. [Department of Chemistry and Department of Physics, and Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)

2006-02-15

442

Toward broadband electroacoustic resonators through optimized feedback control strategies  

NASA Astrophysics Data System (ADS)

This paper presents a methodology for the design of broadband electroacoustic resonators for low-frequency room equalization. An electroacoustic resonator denotes a loudspeaker used as a membrane resonator, the acoustic impedance of which can be modified through proportional feedback control, to match a target impedance. However, such impedance matching only occurs over a limited bandwidth around resonance, which can limit its use for the low-frequency equalization of rooms, requiring an effective control at least up to the Schroeder frequency. Previous experiments have shown that impedance matching can be achieved over a range of a few octaves using a simple proportional control law. But there is still a limit to the feedback gain, beyond which the feedback-controlled loudspeaker becomes non-dissipative. This paper evaluates the benefits of using PID control and phase compensation techniques to improve the overall performance of the electroacoustic resonator. More specifically, it is shown that some adverse effects due to high-order dynamics in the moving-coil transducer can be mitigated. The corresponding control settings are also identified with equivalent electroacoustic resonator parameters, allowing a straightforward design of the controller. Experimental results using PID control and phase compensation are finally compared in terms of sound absorption performances. As a conclusion the overall performances of electroacoustic resonators for damping the modal resonances inside a duct are presented, along with general discussions on practical implementation and the extension to actual room modes damping.

Boulandet, R.; Lissek, H.

2014-09-01

443

Conduction electron spin resonance in AlB2  

NASA Astrophysics Data System (ADS)

This work reports on electron spin resonance experiments in oriented single crystals of the hexagonal AlB2 diboride compound (P6/mmm, D16h structure) which display conduction electron spin resonance. The X-band electron spin resonance spectra showed a metallic Dysonian resonance with g-value and intensity independent of temperature. The thermal broadening of the anisotropic electron spin resonance linewidth ?H tracks the T-dependence of the electrical resistivity below T ? 100 K. These results confirm the observation of a conduction electron spin resonance in AlB2 and are discussed in comparison with other boride compounds. Based on our main findings for AlB2 and the calculated electronic structure of similar layered honeycomb-like structures, we conclude that any array of covalent B-B layers potentially results in a conduction electron spin resonance signal. This observation may shed new light on the nature of the non-trivial conduction electron spin resonance-like signals of complex f-electron systems such as ?-YbAlB4.

Holanda, L. M.; Mendonça-Ferreira, L.; Ribeiro, R. A.; Osorio-Guillén, J. M.; Dalpian, G. M.; Kuga, K.; Nakatsuji, S.; Fisk, Z.; Urbano, R. R.; Pagliuso, P. G.; Rettori, C.

2013-05-01

444

A Wire Crossed-Loop-Resonator for Rapid Scan EPR  

PubMed Central

A crossed-loop (orthogonal mode) resonator (CLR) was constructed of fine wire to achieve design goals for rapid scan in vivo EPR imaging at VHF frequencies (in practice, near 250 MHz). This application requires the resonator to have a very open design to facilitate access to the animal for physiological support during the image acquisition. The rapid scan experiment uses large amplitude magnetic field scans, and sufficiently large resonator and detection bandwidths to record the rapidly-changing signal response. Rapid-scan EPR is sensitive to RF/microwave source noise and to baseline changes that are coherent with the field scan. The sensitivity to source noise is a primary incentive for using a CLR to isolate the detected signal from the RF source noise. Isolation from source noise of 44 and 47 dB was achieved in two resonator designs. Prior results showed that eddy currents contribute to background problems in rapid scan EPR, so the CLR design had to minimize conducting metal components. Using fine (AWG 38) wire for the resonators decreased eddy currents and lowered the resonator Q, thus providing larger resonator bandwidth. Mechanical resonances at specific scan frequencies are a major contributor to rapid scan backgrounds. PMID:21603086

Rinard, George A.; Quine, Richard W.; Biller, Joshua R.; Eaton, Gareth R.

2011-01-01

445