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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

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

4

Z .Solid State Nuclear Magnetic Resonance 11 1998 139156 SQUID detected NMR and NQR  

E-print Network

Z .Solid State Nuclear Magnetic Resonance 11 1998 139­156 SQUID detected NMR and NQR Matthew P dc Superconducting QUantum Interference Device SQUID is a sensitive detector of magnetic flux to a thin film superconducting coil deposited on the SQUID to form a flux transformer. With this untuned

Augustine, Mathew P.

5

Application of nuclear quadrupole resonance to the study of clathrates. sup 35 Cl NQR and crystallography of clathrated CCl sub 4  

SciTech Connect

The {sup 35}Cl nuclear quadrupole resonance (NQR) spectra of CCl{sub 4} in more than 20 clathrates have been measured in the range 4-200 K. The crystal structures of CCl{sub 4}/Dianin's compound (1), CCl{sub 4}/Fe(AcAc){sub 3} (3), CCl{sub 4}/Ni(SCN){sub 2}(3-MePy){sub 4} (4), and CCl{sub 4}/Ni(exan){sub 2}(4,4{prime}-dm-2,2{prime}-bpy) (19) clathrates are also reported. Site symmetry and site multiplicity of the guest molecule in clathrates were determined by NQR spectroscopy and by x-ray crystallography. The degree of host-guest interaction was estimated from the NQR frequency shifts. The libration frequencies of the guest molecules in trigonal cavities were determined from NQR frequencies by Bayer-Kushida theory analysis.

Pang, Li; Lucken, E.A.C.; Bernardinelli, G. (Univ. de Geneve (Switzerland))

1990-11-21

6

Application of nuclear quadrupole resonance to the study of clathrates. sup 35 Cl NQR and crystallography of clathrated CCl sub 4  

Microsoft Academic Search

The ³⁵Cl nuclear quadrupole resonance (NQR) spectra of CClâ in more than 20 clathrates have been measured in the range 4-200 K. The crystal structures of CClâ\\/Dianin's compound (1), CClâ\\/Fe(AcAc)â (3), CClâ\\/Ni(SCN)â(3-MePy)â (4), and CClâ\\/Ni(exan)â(4,4â²-dm-2,2â²-bpy) (19) clathrates are also reported. Site symmetry and site multiplicity of the guest molecule in clathrates were determined by NQR spectroscopy and by x-ray crystallography.

Li Pang; E. A. C. Lucken; G. Bernardinelli

1990-01-01

7

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

8

14 N NQR spectrum of sildenafil citrate  

NASA Astrophysics Data System (ADS)

The 14N nuclear quadrupole resonance (NQR) spectrum of sildenafil citrate tablets has been recorded allowing the quadrupole coupling constants and asymmetry parameters of all six unique nitrogen atoms in its structure to be determined. A density function calculation gives results that are largely in agreement with the experimental values.

Stephenson, David; Singh, Nadia

2014-10-01

9

Exploiting temperature dependency in the detection of NQR signals  

Microsoft Academic Search

Nuclear quadrupole resonance (NQR) offers an unequivocal method of detecting and identifying land mines. Unfortunately, the practical use of NQR is restricted by the low signal-to-noise ratio (SNR), and the means to improve the SNR are vital to enable a rapid, reliable, and convenient system. In this paper, an approximate maximum-likelihood detector (AML) is developed, exploiting the temperature dependency of

Andreas Jakobsson; Magnus Mossberg; Michael D. Rowe; John A. S. Smith

2006-01-01

10

NQR Study of Dynamics in Incommensurate Phases  

NASA Astrophysics Data System (ADS)

Dynamic processes in solids exhibiting structurally incommensurate phases are briefly reviewed, and the application of NMR and NQR is discussed. The unique utility of these methods, - arising due to, on one hand, the microscopic resonant nature of the probe used and, on the other, the presence of periodic, though incommensurable, structure - , is brought out by presenting recent results in a prototype system (Rb2ZnCl4) in the presence of randomly quenched disorder. In particular, the interesting new methodology of measuring, by analysing NQR spin echo modulation, ultra-slow diffusion like collective motions of ensembles of atoms in the presence of pinning effects due to disorder is illustrated with new results.

Sastry, V. S. S.; Venu, K.; Maheswari, S. Uma; Subramanian, R. K.

2000-02-01

11

Nuclear quadrupole resonances in compact vapor cells: the crossover from the NMR to the NQR interaction regimes  

E-print Network

We present the first experimental study that maps the transformation of nuclear quadrupole resonances from the pure nuclear quadrupole regime to the quadrupole-perturbed Zeeman regime. The transformation presents an interesting quantum-mechanical problem, since the quantization axis changes from being aligned along the axis of the electric-field gradient tensor to being aligned along the magnetic field. We achieve large nuclear quadrupole shifts for I = 3/2 131-Xe by using a 1 mm^3 cubic cell with walls of different materials. When the magnetic and quadrupolar interactions are of comparable size, perturbation theory is not suitable for calculating the transition energies. Rather than use perturbation theory, we compare our data to theoretical calculations using a Liouvillian approach and find excellent agreement.

E. A. Donley; J. L. Long; T. C. Liebisch; E. R. Hodby; T. A. Fisher; J. Kitching

2008-12-10

12

Rapid detection of arsenic minerals using portable broadband NQR  

NASA Astrophysics Data System (ADS)

The 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

13

NQR study of chalcogenide glasses Ge-As-Se.  

PubMed

A three-component Ge-As-Se system is studied by the nuclear quadrupole resonance (NQR) method on (75)As nuclei and by the nutation NQR spectroscopy. The NQR (75)As spectra of the glasses Ge(0.021) As(0.375) Se(0.604), Ge(0.043) As(0.348) Se(0.609) and Ge(0.068) As(0.318) Se(0.614) reveal broad lines with two peaks assigned to the main structural unit of As(2)Se(3). With increasing average coordination number ( ?r), the spectrum signals are shifted towards higher frequencies. At ?r > 2.54, the spectrum becomes complex, which is a consequence of formation of more complex molecular structures in the glasses of high content of germanium. At fixed frequencies the asymmetry parameter ? of the samples studied is determined. PMID:21452350

Glotova, Olga; Korneva, Irina; Sinyavsky, Nikolay; Ostafin, Michal; Nogaj, Boleslaw

2011-07-01

14

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

15

Solid-State NMR/NQR and First-Principles Study of Two Niobium Halide Cluster Compounds  

E-print Network

1 Solid-State NMR/NQR and First-Principles Study of Two Niobium Halide Cluster Compounds Berislav : 10.1016/j.ssnmr.2014.02.001 #12;2 Abstract Two hexanuclear niobium halide cluster compounds solid-state NMR/NQR techniques and PAW/GIPAW calculations. For niobium sites the NMR parameters were

Boyer, Edmond

16

Resonant optothermoacoustic detection: technique for measuring weak  

E-print Network

is photoacoustic spec- troscopy (PAS), based on the detection of sound waves generated in a medium upon absorptionResonant optothermoacoustic detection: technique for measuring weak optical absorption by gases October 21, 2010 We report a laser spectroscopy technique for detecting optical absorption in gases

17

Low-frequency nuclear quadrupole resonance with a dc SQUID  

SciTech Connect

Conventional pure nuclear quadrupole resonance (NQR) is a technique well suited for the study of very large quadrupolar interactions. Numerous nuclear magnetic resonance (NMR) techniques have been developed for the study of smaller quadrupolar interactions. However, there are many nuclei which have quadrupolar interactions of intermediate strength. Quadrupolar interactions in this region have traditionally been difficult or unfeasible to detect. This work describes the development and application of a SQUID NQR technique which is capable of measuring intermediate strength quadrupolar interactions, in the range of a few hundred kilohertz to several megahertz. In this technique, a dc SQUID (Superconducting QUantum Interference Device) is used to monitor the longitudinal sample magnetization, as opposed to the transverse magnetization, as a rf field is swept in frequency. This allows the detection of low-frequency nuclear quadrupole resonances over a very wide frequency range with high sensitivity. The theory of this NQR technique is discussed and a description of the dc SQUID system is given. In the following chapters, the spectrometer is discussed along with its application to the study of samples containing half-odd-integer spin quadrupolar nuclei, in particular boron-11 and aluminum-27. The feasibility of applying this NQR technique in the study of samples containing integer spin nuclei is discussed in the last chapter. 140 refs., 46 figs., 6 tabs.

Chang, J.W.

1991-07-01

18

DEVELOPMENTAL NEUROIMAGING OF CHILDREN USING MAGNETIC RESONANCE TECHNIQUES  

E-print Network

DEVELOPMENTAL NEUROIMAGING OF CHILDREN USING MAGNETIC RESONANCE TECHNIQUES Michael J. Rivkin. Recently, powerful qualitative and quantita- tive magnetic resonance techniques have been developed, recent magnetic resonance imaging data related to human brain development during the fetal, neonatal

Stromswold, Karin

19

Weakly first-order behavior in ferromagnetic transition of UCoGe revealed by 59Co-NQR studies  

NASA Astrophysics Data System (ADS)

We have performed 59Co nuclear quadrupole resonance (NQR) measurements on ferromagnetic (FM) superconductor UCoGe, in which ferromagnetism occurs at TCurie ˜ 2.5 K. By measuring NQR spectrum at various temperatures, we investigated the development of local magnetic moment around TCurie, and suggest that FM transition possesses weakly first-order character. This first-order behavior is consistent with the theoretical prediction that the low temperature FM transition in itinerant magnets is generically of first-order.

Hattori, T.; Ishida, K.; Nakai, Y.; Ohta, T.; Deguchi, K.; Sato, N. K.; Satoh, I.

2010-12-01

20

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

21

Review: Magnetic resonance imaging techniques in ophthalmology  

PubMed Central

Imaging the eye with magnetic resonance imaging (MRI) has proved difficult due to the eye’s propensity to move involuntarily over typical imaging timescales, obscuring the fine structure in the eye due to the resulting motion artifacts. However, advances in MRI technology help to mitigate such drawbacks, enabling the acquisition of high spatiotemporal resolution images with a variety of contrast mechanisms. This review aims to classify the MRI techniques used to date in clinical and preclinical ophthalmologic studies, describing the qualitative and quantitative information that may be extracted and how this may inform on ocular pathophysiology. PMID:23112569

Fagan, Andrew J.

2012-01-01

22

Application of 14N NQR to the study of piroxicam polymorphism.  

PubMed

A study was conducted to test the capability of the (14)N nuclear quadrupole resonance (NQR) method to discriminate qualitatively and quantitatively among different forms of piroxicam. Samples of commercial piroxicam form I and its monohydrate were obtained on the local market. Additionally, samples of form I and II were prepared by recrystallization in 1,2-dichloroethane and ethanol, respectively. DSC and FT-IR were employed as reference methods. A (14)N NQR spectrometer was used to measure samples of different forms and mixtures of piroxicam at 2587 and 3439 ?kHz. DSC and FT-IR clearly confirmed differences between the different piroxicam forms. Measurements of (14)N NQR signals of different forms of piroxicam at 2587 ?kHz detected only spectral peaks of form I. The dependence of (14)N NQR signal intensity on the concentration of form I in mixtures with the monohydrate showed a clear linear relationship at both measured frequencies, though the scattering of data was greater at 3439 ?kHz due to the lower S/N ratio. The (14)N NQR method has the potential to become an additional and important spectroscopic tool in the study of solid-state forms, not only of pure active pharmaceutical ingredients or excipients, but also of their mixtures. This ability lends the method to a possible successful utilization at different levels of pharmaceutical manufacturing and product quality control. PMID:20597116

Lavri?, Zoran; Pirnat, Janez; Lužnik, Janko; Seliger, Janez; Zagar, Veselko; Trontelj, Zvonko; Sr?i?, Stane

2010-12-01

23

A computational NQR study on the hydrogen-bonded lattice of cytosine-5-acetic acid.  

PubMed

A computational study at the level of density functional theory (DFT) employing 6-311++G** standard basis set was carried out to evaluate nuclear quadrupole resonance (NQR) spectroscopy parameters in cytosine-5-acetic acid (C5AA). Since the electric field gradient (EFG) tensors are very sensitive to the electrostatic environment at the sites of quadruple nuclei, the most possible interacting molecules with the target one were considered in a five-molecule model system of C5AA using X-ray coordinates transforming. The hydrogen atoms positions were optimized and two model systems of original and H-optimized C5AA were considered in NQR calculations. The calculated EFG tensors at the sites of (17)O, (14)N, and (2)H nuclei were converted to their experimentally measurable parameters, quadrupole coupling constants and asymmetry parameters. The evaluated NQR parameters reveal that the nuclei in original and H-optimized systems contribute to different hydrogen bonding (HB) interaction. The comparison of calculated parameters between optimized isolated gas-phase and crystalline monomer also shows the relationship between the structural deformation and NQR parameters in C5AA. The basis set superposition error (BSSE) calculations yielded no significant errors for employed basis set in the evaluation of NQR parameters. All the calculations were performed by Gaussian 98 package of program. PMID:17926341

Mirzaei, Mahmoud; Hadipour, Nasser L

2008-04-15

24

Is Dynamic Mechanical Analysis (DMA) a non-resonance technique?  

Microsoft Academic Search

Dynamic Mechanical Analysis is an experimental technique commonly used to study the viscoelastic behaviour of materials over a range of temperatures and frequencies. Although considered as a forced non-resonance technique, the warned users perfectly know that resonant frequencies are inevitably encountered on the typical frequency range of DMA apparatus. In consequences, the measured properties in the area of the resonant

V. Placet; E. Foltête

2010-01-01

25

A Technique for Adjusting Eigenfrequencies of WGM Resonators  

NASA Technical Reports Server (NTRS)

A simple technique has been devised for making small, permanent changes in the eigenfrequencies (resonance frequencies) of whispering-gallery-mode (WGM) dielectric optical resonators that have high values of the resonance quality factor (Q). The essence of the technique is to coat the resonator with a thin layer of a transparent polymer having an index of refraction close to that of the resonator material. Successive small frequency adjustments can be made by applying successive coats. The technique was demonstrated on a calcium fluoride resonator to which successive coats of a polymer were applied by use of a hand-made wooden brush. To prevent temperature- related frequency shifts that could interfere with the verification of the effectiveness of this technique, the temperature of the resonator was stabilized by means of a three-stage thermoelectric cooler. Measurements of the resonator spectrum showed the frequency shifts caused by the successive coating layers.

Strekalov, Dmitry; Savchenkov, Anatoliy; Maleki, Lute; Matsko, Andrey; Iltchenko, Vladimir; Martin, Jan

2009-01-01

26

MAGNETIC RESONANCE ELECTRICAL IMPEDANCE TOMOGRAPHY (MR-EIT): A new technique for high resolution conductivity imaging  

E-print Network

MAGNETIC RESONANCE ELECTRICAL IMPEDANCE TOMOGRAPHY (MR-EIT): A new technique for high resolution field measurements are performed by using magnetic resonance imaging techniques. The conductivity resonance imaging (MRI) techniques, if the conductor contains magnetic resonance active nuclei [2

Eyüboðlu, Murat

27

Ultrasonic signal enhancement by resonator techniques  

NASA Technical Reports Server (NTRS)

Ultrasonic resonators increase experimental sensitivity to acoustic dispersion and changes in attenuation. Experimental sensitivity enhancement line shapes are presented which were obtained by modulating the acoustic properties of a CdS resonator with a light beam. Small changes in light level are made to produce almost pure absorptive or dispersive changes in the resonator signal. This effect is due to the coupling of the ultrasonic wave to the CdS conductivity which is proportional to incident light intensity. The resonator conductivity is adjusted in this manner to obtain both dispersive and absorptive sensitivity enhancement line shapes. The data presented verify previous thoretical calculations based on a propagating wave model.

Heyman, J. S.

1973-01-01

28

Analysis and calibration techniques for superconducting resonators.  

PubMed

A method is proposed and experimentally explored for in-situ calibration of complex transmission data for superconducting microwave resonators. This cryogenic calibration method accounts for the instrumental transmission response between the vector network analyzer reference plane and the device calibration plane. Once calibrated, the observed resonator response is analyzed in detail by two approaches. The first, a phenomenological model based on physically realizable rational functions, enables the extraction of multiple resonance frequencies and widths for coupled resonators without explicit specification of the circuit network. In the second, an ABCD-matrix representation for the distributed transmission line circuit is used to model the observed response from the characteristic impedance and propagation constant. When used in conjunction with electromagnetic simulations, the kinetic inductance fraction can be determined with this method with an accuracy of 2%. Datasets for superconducting microstrip and coplanar-waveguide resonator devices were investigated and a recovery within 1% of the observed complex transmission amplitude was achieved with both analysis approaches. The experimental configuration used in microwave characterization of the devices and self-consistent constraints for the electromagnetic constitutive relations for parameter extraction are also presented. PMID:25638068

Cataldo, Giuseppe; Wollack, Edward J; Barrentine, Emily M; Brown, Ari D; Moseley, S Harvey; U-Yen, Kongpop

2015-01-01

29

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

30

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

NASA Astrophysics Data System (ADS)

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 14N 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 14N 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 14N NQR based detection device.

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

2014-10-01

31

93Nb- and 27Al-NMR/NQR studies of the praseodymium based PrNb2Al20  

NASA Astrophysics Data System (ADS)

We report a study of 93Nb- and 27Al-nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) in a praseodymium based compound PrNb2Al20. The observed NMR line at around 3 T and 30 K shows a superposition of typical powder patterns of one Nb signal and at least two Al signals. 93Nb-NMR line could be reproduced by using the previously reported NQR frequency ?Q ? 1.8MHz and asymmetry parameter ? ? 0 [Kubo T et al 2014 JPS Conf. Proc. 3 012031]. From 27Al-NMR/NQR, NQR parameters are obtained to be ?Q,A ? 1.53 MHz, and ?A ? 0.20 for the site A, and ?Q,B ? 2.28 MHz, and ?B ? 0.17 for the site B. By comparing this result with the previous 27Al-NMR study of PrT2Al20 (T = Ti, V) [Tokunaga Y et al 2013 Phys. Rev. B 88 085124], these two Al site are assigned to the two of three crystallographycally inequivalent Al sites.

Kubo, Tetsuro; Kotegawa, Hisashi; Tou, Hideki; Higashinaka, Ryuji; Nakama, Akihiro; Aoki, Yuji; Sato, Hideyuki

2015-03-01

32

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

33

Mixed radiation field dosimetry utilizing Nuclear Quadrupole Resonance  

SciTech Connect

This project has proposed to develop a novel dosimetry system that is capable of directly evaluating the chemical/biological damage caused by neutrons, photons, or both in a single measurement. The dosimeter itself will consist of a small volume of biological equivalent material that is probed for radiation damage with Nuclear Quadrupole Resonance (NQR) techniques. NQR has previously been utilized as a sensitive probe of structural and chemical changes at the molecular level for a variety of organic compounds. The biological equivalent materials used in this study will not only have a density similar to tissue (tissue equivalent) but will have the same atomic components as tissue. This is a significant requirement if the important neutron interactions that occur in tissue are to occur in the dosimeter as well. The overall objective of this study is to investigate a methodology to perform accurate mixed-field (neutron and photon) dosimetry for biological systems.

Hintenlang, D.

1991-01-01

34

Measuring Cerebral Blood Flow Using Magnetic Resonance Imaging Techniques  

Microsoft Academic Search

Magnetic resonance imaging techniques measuring CBF have developed rapidly in the last decade, resulting in a wide range of available methods. The most successful approaches are based either on dynamic tracking of a bolus of a paramagnetic contrast agent (dynamic susceptibility contrast) or on arterial spin labeling. This review discusses their principles, possible pitfalls, and potential for absolute quantification and

Fernando Calamante; David L. Thomas; Gaby S. Pell; Jonna Wiersma; Robert Turner

1999-01-01

35

NQR Line Broadening Due to Crystal Lattice Imperfections and Its Relationship to Shock Sensitivity  

NASA Astrophysics Data System (ADS)

The hydrodynamic hot spot model is used to explain the difference between shock sensitive and shock insensitive explosives. Among the major factors that influence the shock sensitivity of energetic compounds are the quality and particle size of the energetic crystals used to formulate the cast plastic bonded explosive. As do all energetic compounds, RDX and HMX exhibit internal crystal defects the magnitude and type of which depend on the manufacturing process used to synthesize and re-crystallize the energetic compound. Nuclear Quadrupole Resonance (NQR) spectroscopy was used to determine the crystal quality of RDX, HMX and CL-20 obtained from various manufacturers. The NQR experimental results are discussed. Cast plastic bonded explosives were made using the RDX and HMX obtained from the various manufacturers and subsequently subjected to the NOL large-scale gap test (LSGT). The results of the LSGT are discussed and correlated with the NQR results. A relationship between the crystal defect density and shock initiation pressure of the plastic bonded explosive is developed and discussed.

Caulder, S. M.; Buess, M. L.; Garroway, A. N.; Miller, P. J.

2004-07-01

36

Resonant ultrasound spectroscopy (RUS) is a non-destructive technique originally developed for evaluating  

E-print Network

RUS Resonant ultrasound spectroscopy (RUS) is a non- destructive technique originally developed measurement results. Resonant ultrasound spectroscopy (RUS) is a non-destructive material characterisation

37

35Cl-NQR and DFT study of electronic structure of amlodipine and felodipine vascular-selective drugs from the dihydropyridine Ca ++ antagonists group  

NASA Astrophysics Data System (ADS)

Amlodipine (AM) and felodipine (FL) have been studied in solid state by the nuclear quadrupole resonance (NQR) and density functional theory (DFT). The results have shown that NQR data do not permit a differentiation between R and S enantiomers, which is a consequence of the symmetry of the 4-aryl ring, whereas they permit a differentiation between free bases and salts. The HOMO-LUMO gap is smaller for AM than for FL, which suggests smaller energy of excitation for AM. The absolute hardness, chemical potential and electrophilicity of both AM enantiomers are lower than the corresponding values for FL enantiomers, suggesting that AM should be more reactive than FL in unimolecular reactions.

Latosi?ska, J. N.; Latosi?ska, M.; Kasprzak, J.

2008-09-01

38

Zero-field NMR and NQR studies of magnetically ordered state in charge-ordered EuPtP  

NASA Astrophysics Data System (ADS)

EuPtP undergoes two valence transitions and has two kinds of valence states of Eu ions at low temperatures. In the charge-ordered state, this compound shows an antiferromagnetic order ascribed to magnetic divalent Eu ions. We investigated the antiferromagnetically ordered state of EuPtP by nuclear magnetic resonance (NMR) measurement and nuclear quadrupole resonance (NQR) measurement in a zero external magnetic field. The observed 153Eu NMR signals of a magnetic divalent state and Eu,153151 NQR signals of a nonmagnetic trivalent state clearly demonstrate that the spins order in the hexagonal basal plane and the internal magnetic field is not canceled out, even at the Eu3 + layers which are in the middle of magnetic Eu2 + layers. In addition, the observation of 31P and 195Pt NMR spectra allowed us to discuss a possible magnetic structure. We also evaluated the nuclear quadrupole frequencies for both Eu2 + and Eu3 + ion states.

Koyama, T.; Maruyama, T.; Ueda, K.; Mito, T.; Mitsuda, A.; Umeda, M.; Sugishima, M.; Wada, H.

2015-03-01

39

Magnetic Resonance Imaging Techniques: fMRI, DWI, and PWI  

PubMed Central

Magnetic resonance imaging (MRI) is a noninvasive technique which can acquire important quantitative and anatomical information from an individual in any plane or volume at comparatively high resolution. Over the past several years, developments in scanner hardware and software have enabled the acquisition of fast MRI imaging, proving extremely useful in various clinical and research applications such as in brain mapping or functional MRI (fMRI), perfusion-weighted imaging (PWI), and diffusion-weighted imaging (DWI). These techniques have revolutionized the use of MRI in the clinics, providing great insight into physiologic mechanisms and pathologic conditions. Since these relatively new areas of MRI have relied on fast scanning techniques, they have only recently been widely introduced to clinical sites. As such, this review article is devoted to the technological aspects of these techniques, as well as their roles and limitations in neuroimaging applications. PMID:18843569

Holdsworth, Samantha J.; Bammer, Roland

2012-01-01

40

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

Microsoft Academic Search

Nuclear quadrupole resonance (NQR) parameters of 14N, 2H of N2H 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

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

2004-01-01

41

Resonance measurements techniques of optical whispering gallery mode mini-disc resonators for microwave photonics applications  

NASA Astrophysics Data System (ADS)

The aim of this work is to compare advantages and disadvantages of different techniques for coupling a mini-discoptical- resonator to determine quality factor of its resonance. Optical fiber coupled to a resonator consists in a mini disc with whispering gallery modes at its circumference. We choose to work with three materials and design compact miniresonators. Fused silica is found to be suitable for these applications thanks to its hardness in the range 6-7 and the behavior to mechanical shocks, despite its sensitivity to water pollution. With its tetragonal crystal and a good behavior with risk of water pollution, Calcium fluoride is a good candidate despite sensitivity to mechanical shocks. Magnesium fluoride is the third material used. As a critical step, taper coupling is set with a 20nm resolution positioning system. Miniresonator is excited from a system equipped with a tunable laser diode with a tunability from 1490 to 1640 nm and a linewidth narrower than 300kHz. Light is coupled into the microsphere either from glass or fiber prism or with fiber taper via evanescent field. We have also used a single frequency 660nm laser diode with a linewidth narrower than 100kHz which can be tuned about 10pm to test a single resonant peak. Both sources are used with either a tapered fiber or a filed fiber. Resonance is observed and quality factor of the resonators is found to be in the range of 108.

Salzenstein, Patrice; Jelínek, Michal; Chembo, Yanne K.; Pogurmiskiy, Maxim; Tavernier, Hervé; Volyanskiy, Kirill; Phan Huy, Kien; Chauvet, Mathieu; Larger, Laurent; Kubecek, Václav

2011-06-01

42

Investigation of ferromagnetic resonance by the inelastic light scattering technique  

NASA Astrophysics Data System (ADS)

The ferromagnetic resonance at X-band microwave frequency is detected by the inelastic light scattering technique. The spin precession generates frequency shifted light contained in the direct laser beam which is observed either in transmission or reflection. Discrimination from the unshifted light is done with a tandem 4+2 pass Fabry-Perot interferometer. The microwave excitation is performed with conventional waveguide techniques and with planar microwave structures. YIG platelets, epitaxial YIG films on GGG substrate, iron borate platelets and single crystal iron films on GaAs substrates are investigated. The method is very sensitive; under favourable conditions even the thermally excited uniform precession (i.e. no microwave excitation) can be detected. Furthermore the technique allows spatially resolved recording of the FMR intensity.

Wettling, W.; Jantz, W.

1984-11-01

43

Resonant marker design and fabrication techniques for device visualization during interventional magnetic resonance imaging.  

PubMed

Magnetic resonance imaging (MRI) has great potential as an imaging modality for guiding minimally invasive interventions because of its superior soft tissue contrast and the possibility of arbitrary slice positioning while avoiding ionizing radiation and nephrotoxic iodine contrast agents. The major constraints are: limited patient access, the insufficient assortment of compatible instruments and the difficult device visualization compared to X-ray based techniques. For the latter, resonant MRI markers, fabricated by using the wire-winding technique, have been developed. This fabrication technique serves as a functional model but has no clinical use. Thus, the aim of this study is to illustrate a four-phase design process of resonant markers involving microsystems technologies. The planning phase comprises the definition of requirements and the simulation of electromagnetic performance of the MRI markers. The following technologies were considered for the realization phase: aerosol-deposition process, hot embossing technology and thin film technology. The subsequent evaluation phase involves several test methods regarding electrical and mechanical characterization as well as MRI visibility aspects. The degree of fulfillment of the predefined requirements is determined within the analysis phase. Furthermore, an exemplary evaluation of four realized MRI markers was conducted, focusing on the performance within the MRI environment. PMID:25460277

Kaiser, Mandy; Detert, Markus; Rube, Martin A; El-Tahir, Abubakr; Elle, Ole Jakob; Melzer, Andreas; Schmidt, Bertram; Rose, Georg H

2015-04-01

44

Functional magnetic resonance imaging: imaging techniques and contrast mechanisms.  

PubMed Central

Functional magnetic resonance imaging (fMRI) is a widely used technique for generating images or maps of human brain activity. The applications of the technique are widespread in cognitive neuroscience and it is hoped they will eventually extend into clinical practice. The activation signal measured with fMRI is predicated on indirectly measuring changes in the concentration of deoxyhaemoglobin which arise from an increase in blood oxygenation in the vicinity of neuronal firing. The exact mechanisms of this blood oxygenation level dependent (BOLD) contrast are highly complex. The signal measured is dependent on both the underlying physiological events and the imaging physics. BOLD contrast, although sensitive, is not a quantifiable measure of neuronal activity. A number of different imaging techniques and parameters can be used for fMRI, the choice of which depends on the particular requirements of each functional imaging experiment. The high-speed MRI technique, echo-planar imaging provides the basis for most fMRI experiments. The problems inherent to this method and the ways in which these may be overcome are particularly important in the move towards performing functional studies on higher field MRI systems. Future developments in techniques and hardware are also likely to enhance the measurement of brain activity using MRI. PMID:10466145

Howseman, A M; Bowtell, R W

1999-01-01

45

Nuclear Magnetic Resonance (NMR) is the only logging technique available to estimate pore-size  

E-print Network

1 ABSTRACT Nuclear Magnetic Resonance (NMR) is the only logging technique available to estimate, Nuclear Magnetic Resonance (NMR) logging has been used to assess a handful of key petrophysical parameters

Torres-Verdín, Carlos

46

The use of spectroscopic techniques (especially phosphorus-31 nuclear magnetic resonance [31  

E-print Network

1617 The use of spectroscopic techniques (especially phosphorus-31 nuclear magnetic resonance [31 P; Shober et al., 2006; Toor et al., 2005a, 2005b) and solid-state phosphorus-31 nuclear magnetic resonance

Sparks, Donald L.

47

Quantitative Proton Magnetic Resonance Techniques for Measuring Fat  

PubMed Central

Accurate, precise, and reliable techniques for quantifying body and organ fat distributions are important tools in physiology research. They are critically needed in studies of obesity and diseases involving excess fat accumulation. Proton magnetic resonance methods address this need by providing an array of relaxometry-based (T1, T2) and chemical-shift-based approaches. These techniques can generate informative visualizations of regional and whole-body fat distributions, yield measurements of fat volumes within specific body depots, and quantify fat accumulation in abdominal organs and muscles. MR methods are commonly used to investigate the role of fat in nutrition and metabolism, to measure the efficacy of short and long-term dietary and exercise interventions, to study the implications of fat in organ steatosis and muscular dystrophies, and to elucidate pathophysiological mechanisms in the context of obesity and its comorbidities. The purpose of this review is to provide a summary of mainstream MR strategies for fat quantification. The article will succinctly describe the principles that differentiate water and fat proton signals, summarize advantages and limitations of various techniques, and offer a few illustrative examples. The article will also highlight recent efforts in MR of brown adipose tissue and conclude by briefly discussing some future research directions. PMID:24123229

Harry, Houchun; Kan, Hermien E.

2014-01-01

48

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

49

The Hairpin Resonator: A New Look at an Old Technique  

NASA Astrophysics Data System (ADS)

R. L Stenzel(1) first introduced a microwave resonator probe (referred to here as a hairpin probe) to measure local electron density in a low-pressure plasma discharge. Judging from literature citations, this technique appears to be rarely used. In order to compare electron density measurements of a Langmuir probe and microwave interferometer measurements, a hairpin probe was designed and built. Stenzel's original design was modified to increase coupling to the hairpin structure, to reduce cross coupling to the pick-up probe and to minimize plasma perturbation. In addition, a sheath correction was determined based on the fluid equations for collisionless ions in a cylindrical electron-free sheath, coupled with a determination of the capacitance between hairpin wires. Instead of using the microwave setup described by Stenzel(1) (sweep oscillator, TWT amplified, detector, Boxcar integrator X-Y recorder) an "off the shelf" spectrum analyzer with a tracking generator was used to monitor resonant frequency of the hairpin. The result of these changes is a relatively simple diagnostic tool that can be used to determine the electron density in a low-pressure plasma discharge. This system is believed to be accurate and has been found to be highly reproducible from day to day. Measurements are relatively easy to interpret. The hairpin probe can be used in rf and dc low-pressure discharges and in chemically active discharges where probe surface contamination is significant. It is also useable in weakly magnetized plasmas. In this work we discuss probe construction, design and usage. In addition, a series of measurements comparing the results of the hairpin probe, Langmuir probe and microwave interferometer results are also presented. The hairpin probe is a valuable plasma diagnostic technique that has been overlooked for too long. (1) R. L. Stenzel, Rev. Sci. Instrum., Vol. 47, No. 5, p. 503, (1976)

Piejak, Robert; Godyak, Valery; Garner, Richard; Alexandrovich, Benjamin

2003-10-01

50

Magnetic resonance techniques for investigation of multiple sclerosis  

NASA Astrophysics Data System (ADS)

Multiple sclerosis (MS) is a common neurological disease which can cause loss of vision and balance, muscle weakness, impaired speech, fatigue, cognitive dysfunction and even paralysis. The key pathological processes in MS are inflammation, edema, myelin loss, axonal loss and gliosis. Unfortunately, the cause of MS is still not understood and there is currently no cure. Magnetic resonance imaging (MRI) is an important clinical and research tool for MS. 'Conventional' MRI images of MS brain reveal bright lesions, or plaques, which demark regions of severe tissue damage. Conventional MRI has been extremely valuable for the diagnosis and management of people who have MS and also for the assessment of therapies designed to reduce inflammation and promote repair. While conventional MRI is clearly valuable, it lack pathological specificity and, in some cases, sensitivity to non-lesional pathology. Advanced MR techniques have been developed to provide information that is more sensitive and specific than what is available with clinical scanning. Diffusion tensor imaging and magnetization transfer provide a general but non-specific measure of the pathological state of brain tissue. MR spectroscopy provides concentrations of brain metabolites which can be related to specific pathologies. Myelin water imaging was designed to assess brain myelination and has proved useful for measuring myelin loss in MS. To combat MS, it is crucial that the pharmaceutical industry finds therapies which can reverse the neurodegenerative processes which occur in the disease. The challenge for magnetic resonance researchers is to design imaging techniques which can provide detailed pathological information relating to the mechanisms of MS therapies. This paper briefly describes the pathologies of MS and demonstrates how MS-associated pathologies can be followed using both conventional and advanced MR imaging protocols.

MacKay, Alex; Laule, Cornelia; Li, David K. B.; Meyers, Sandra M.; Russell-Schulz, Bretta; Vavasour, Irene M.

2014-11-01

51

Novel nuclear magnetic resonance techniques for studying biological molecules  

SciTech Connect

Over the fifty-five year history of Nuclear Magnetic Resonance (NMR), considerable progress has been made in the development of techniques for studying the structure, function, and dynamics of biological molecules. The majority of this research has involved the development of multi-dimensional NMR experiments for studying molecules in solution, although in recent years a number of groups have begun to explore NMR methods for studying biological systems in the solid-state. Despite this new effort, a need still exists for the development of techniques that improve sensitivity, maximize information, and take advantage of all the NMR interactions available in biological molecules. In this dissertation, a variety of novel NMR techniques for studying biomolecules are discussed. A method for determining backbone ({phi}/{psi}) dihedral angles by comparing experimentally determined {sup 13}C{sub a}, chemical-shift anisotropies with theoretical calculations is presented, along with a brief description of the theory behind chemical-shift computation in proteins and peptides. The utility of the Spin-Polarization Induced Nuclear Overhauser Effect (SPINOE) to selectively enhance NMR signals in solution is examined in a variety of systems, as are methods for extracting structural information from cross-relaxation rates that can be measured in SPINOE experiments. Techniques for the production of supercritical and liquid laser-polarized xenon are discussed, as well as the prospects for using optically pumped xenon as a polarizing solvent. In addition, a detailed study of the structure of PrP 89-143 is presented. PrP 89-143 is a 54 residue fragment of the prion proteins which, upon mutation and aggregation, can induce prion diseases in transgenic mice. Whereas the structure of the wild-type PrP 89-143 is a generally unstructured mixture of {alpha}-helical and {beta}-sheet conformers in the solid state, the aggregates formed from the PrP 89-143 mutants appear to be mostly {beta}-sheet.

Laws, David D.

2000-06-01

52

Defective BN Nanotubes: A Density Functional Theory Study of B-11 and N-14 NQR Parameters  

NASA Astrophysics Data System (ADS)

A density functional theory (DFT) study is performed to investigate the influence of structural defects on the electronic structure properties of perfect boron nitride nanotubes (BNNTs). To this aim, as representative models, the single-walled (6,0) BNNT consisting of 36 boron, 36 nitrogen, and 12 hydrogen atoms and the single-walled (4,4) BNNT consisting of 36 boron, 36 nitrogen, and 16 hydrogen atoms are considered. The nuclear quadrupole resonance (NQR) parameters are calculated and compared in two perfect and defective models of the considered BNNTs. The results indicate that due to formation of non-hexagonal rings in the defective model because of removing a B-N bond, the NQR parameters at the sites of first neighbouring nuclei are significantly influenced by imposed perturbation, however, the sites of other nuclei, farther from perturbation, remain almost unchanged. The calculations are performed at the level of the BLYP method and 6-31G* standard basis set using the GAUSSIAN 98 package

Giahi, Masoud; Mirzaei, Mahmoud

2009-04-01

53

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

54

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

55

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

56

Threshold-crossing counting technique for damping factor determination of resonator sensors  

NASA Astrophysics Data System (ADS)

The behavior of resonator-type sensors at resonance is characterized by two fundamental parameters: resonance frequency and damping factor (or Q-factor). Practical applications require accurate and efficient measurements of these two parameters. Using magnetoelastic resonant sensors as a test case earlier work [K. Zeng, K. G. Ong, C. Mungle, and C. A. Grimes, Rev. Sci. Instrum. 73, 4375 (2002)] demonstrated the ability to determine resonance frequency by counting the number of cycles in the transient response of a pulsewise excited sensor. Presented in this paper is a novel technique for measuring the damping factor of a resonant magnetoelastic sensor, or any resonator type sensor, using threshold-crossing counting of the transient response. The damping factor determination technique eliminates the need for a lock-in amplifier or FFT analysis as in the conventional method of quality factor estimation from spectrum analysis, significantly simplifying the electronic implementation as well as improving measurement speed and accuracy.

Zeng, Kefeng; Grimes, Craig A.

2004-12-01

57

An ultra-broadband low-frequency magnetic resonance system.  

PubMed

MR probes commonly employ resonant circuits for efficient RF transmission and low-noise reception. These circuits are narrow-band analog devices that are inflexible for broadband and multi-frequency operation at low Larmor frequencies. We have addressed this issue by developing an ultra-broadband MR probe that operates in the 0.1-3MHz frequency range without using conventional resonant circuits for either transmission or reception. This "non-resonant" approach significantly simplifies the probe circuit and allows robust operation without probe tuning while retaining efficient power transmission and low-noise reception. We also demonstrate the utility of the technique through a variety of NMR and NQR experiments in this frequency range. PMID:24632101

Mandal, S; Utsuzawa, S; Cory, D G; Hürlimann, M; Poitzsch, M; Song, Y-Q

2014-05-01

58

An ultra-broadband low-frequency magnetic resonance system  

NASA Astrophysics Data System (ADS)

MR probes commonly employ resonant circuits for efficient RF transmission and low-noise reception. These circuits are narrow-band analog devices that are inflexible for broadband and multi-frequency operation at low Larmor frequencies. We have addressed this issue by developing an ultra-broadband MR probe that operates in the 0.1-3 MHz frequency range without using conventional resonant circuits for either transmission or reception. This “non-resonant” approach significantly simplifies the probe circuit and allows robust operation without probe tuning while retaining efficient power transmission and low-noise reception. We also demonstrate the utility of the technique through a variety of NMR and NQR experiments in this frequency range.

Mandal, S.; Utsuzawa, S.; Cory, D. G.; Hürlimann, M.; Poitzsch, M.; Song, Y.-Q.

2014-05-01

59

Nuclear quadrupole resonance studies of amorphous, orthorhombic, and rhombohedral arsenic  

Microsoft Academic Search

Pulsed nuclear quadrupole resonance (NQR) experiments have been performed on three forms of elemental arsenic: amorphous (a), rhombohedral (rh), and orthorhombic (or). The temperature dependence of the spin-lattice relaxation time (T1) provides evidence for the existence of disorder (tunneling) modes in a-As. It is found that the NQR line shape of a-As is highly asymmetric, and this asymmetry is attributed

G. E. Jellison Jr.; G. L. Petersen; P. C. Taylor

1980-01-01

60

Nuclear quadrupole resonance studies of amorphous, orthorhombic, and rhombohedral arsenic  

Microsoft Academic Search

Pulsed nuclear quadrupole resonance (NQR) experiments have been performed on three forms of elemental arsenic: amorphous (a), rhombohedral (rh), and orthorhombic (or). The temperature dependence of the spin-lattice relaxation time (Tâ) provides evidence for the existence of disorder (tunneling) modes in a-As. It is found that the NQR line shape of a-As is highly asymmetric, and this asymmetry is attributed

G. E. Jr. Jellison; G. L. Petersen; P. C. Taylor

1980-01-01

61

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

62

ADVANCES IN OPTICALLY PUMPED He4 MAGNETOMETERS : RESONANCE AND NONRESONANCE TECHNIQUES  

E-print Network

to the observed magnetic field are presented in this paper. The orientation dependence of the amplitude and frequency of the magnetic resonance signal observed by optical techniques has been measured. These results are theoretically interpreted by taking into account the contribution of the indi- vidual magnetic resonances

Boyer, Edmond

63

Surface Plasmon Resonance: An Introduction to a Surface Spectroscopy Technique  

ERIC Educational Resources Information Center

Surface plasmon resonance (SPR) has become an important optical biosensing technology in the areas of biochemistry, biology, and medical sciences because of its real-time, label-free, and noninvasive nature. The high cost of commercial devices and consumables has prevented SPR from being introduced in the undergraduate laboratory. Here, we present…

Tang, Yijun; Zeng, Xiangqun; Liang, Jennifer

2010-01-01

64

The hairpin resonator: A plasma density measuring technique revisited  

NASA Astrophysics Data System (ADS)

A microwave resonator probe is a resonant structure from which the relative permittivity of the surrounding medium can be determined. Two types of microwave resonator probes (referred to here as hairpin probes) have been designed and built to determine the electron density in a low-pressure gas discharge. One type, a transmission probe, is a functional equivalent of the original microwave resonator probe introduced by R. L. Stenzel [Rev. Sci. Instrum. 47, 603 (1976)], modified to increase coupling to the hairpin structure and to minimize plasma perturbation. The second type, a reflection probe, differs from the transmission probe in that it requires only one coaxial feeder cable. A sheath correction, based on the fluid equations for collisionless ions in a cylindrical electron-free sheath, is presented here to account for the sheath that naturally forms about the hairpin structure immersed in plasma. The sheath correction extends the range of electron density that can be accurately measured with a particular wire separation of the hairpin structure. Experimental measurements using the hairpin probe appear to be highly reproducible. Comparisons with Langmuir probes show that the Langmuir probe determines an electron density that is 20-30% lower than the hairpin. Further comparisons, with both an interferometer and a Langmuir probe, show hairpin measurements to be in good agreement with the interferometer while Langmuir probe measurements again result in a lower electron density.

Piejak, R. B.; Godyak, V. A.; Garner, R.; Alexandrovich, B. M.; Sternberg, N.

2004-04-01

65

Magnetic resonance techniques in the assessment of myelin and myelination  

Microsoft Academic Search

Leukodystrophy is a common central nervous system manifestation of inborn errors of metabolism. Until magnetic resonance imaging (MRI) emerged as a clinical tool, the diagnosis of leukodystrophy was difficult and imprecise; MRI has allowed new understandings and classifications of leukodystrophies that have greatly enhanced both our diagnostic ability and our understanding of these complex disorders. However, optimal use of MRI

A. J. Barkovich

2005-01-01

66

Implementation of State Transfer Hamiltonians in Spin Chains with Magnetic Resonance Techniques  

E-print Network

Nuclear spin systems and magnetic resonance techniques have provided a fertile platform for experimental investigation of quantum state transfer in spin chains. From the first observation of polarization transfer, predating ...

Cappellaro, Paola

2014-01-01

67

Coal thickness gauge using RRAS techniques, part 1. [radiofrequency resonance absorption  

NASA Technical Reports Server (NTRS)

A noncontacting sensor having a measurement range of 0 to 6 in or more, and with an accuracy of 0.5 in or better is needed to control the machinery used in modern coal mining so that the thickness of the coal layer remaining over the rock is maintained within selected bounds. The feasibility of using the radiofrequency resonance absorption (RRAS) techniques of electron magnetic resonance (EMR) and nuclear magnetic resonance (NMR) as the basis of a coal thickness gauge is discussed. The EMR technique was found, by analysis and experiments, to be well suited for this application.

Rollwitz, W. L.; King, J. D.

1978-01-01

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

Methods for magnetic resonance analysis using magic angle technique  

DOEpatents

Methods of performing a magnetic resonance analysis of a biological object are disclosed that include placing the object in a main magnetic field (that has a static field direction) and in a radio frequency field; rotating the object at a frequency of less than about 100 Hz around an axis positioned at an angle of about 54.degree.44' relative to the main magnetic static field direction; pulsing the radio frequency to provide a sequence that includes a phase-corrected magic angle turning pulse segment; and collecting data generated by the pulsed radio frequency. In particular embodiments the method includes pulsing the radio frequency to provide at least two of a spatially selective read pulse, a spatially selective phase pulse, and a spatially selective storage pulse. Further disclosed methods provide pulse sequences that provide extended imaging capabilities, such as chemical shift imaging or multiple-voxel data acquisition.

Hu, Jian Zhi (Richland, WA); Wind, Robert A. (Kennewick, WA); Minard, Kevin R. (Kennewick, WA); Majors, Paul D. (Kennewick, WA)

2011-11-22

70

Waveguide-type optical passive ring resonator gyro using frequency modulation spectroscopy technique  

NASA Astrophysics Data System (ADS)

This paper reports the experimental results of silica on a silicon ring resonator in a resonator micro optic gyroscope based on the frequency modulation spectroscopy technique by our research group. The ring resonator is composed of a 4 cm diameter silica waveguide. By testing at ? = 1550 nm, the FSR, FWHM and the depth of resonance are 3122 MHz, 103.07 MHz and 0.8 respectively. By using a polarization controller, the resonance curve under the TM mode can be inhibited. The depth of resonance increased from 0.8 to 0.8913, namely the finesse increase from 30.33 to 33.05. In the experiments, there is an acoustic-optical frequency shifter (AOFS) in each light loop. We lock the lasing frequency at the resonance frequency of the silica waveguide ring resonator for the counterclockwise lightwave; the frequency difference between the driving frequencies of the two AOFS is equivalent to the Sagnac frequency difference caused by gyro rotation. Thus, the gyro output is observed. The slope of the linear fit is about 0.330 mV/(°/s) based on the ?900 to 900 kHz equivalent frequency and the gyro dynamic range is ±2.0 × 103 rad/s.

Liang, Ning; Lijun, Guo; Mei, Kong; Tuoyuan, Chen

2014-12-01

71

Foil cycling technique for the VESUVIO spectrometer operating in the resonance detector configuration  

SciTech Connect

This article reports a novel experimental technique, namely, the foil cycling technique, developed on the VESUVIO spectrometer (ISIS spallation source) operating in the resonance detector configuration. It is shown that with a proper use of two foils of the same neutron absorbing material it is possible, in a double energy analysis process, to narrow the width of the instrumental resolution of a spectrometer operating in the resonance detector configuration and to achieve an effective subtraction of the neutron and gamma backgrounds. Preliminary experimental results, obtained from deep inelastic neutron scattering measurements on lead, zirconium hydride, and deuterium chloride samples, are presented.

Schooneveld, E. M.; Mayers, J.; Rhodes, N. J.; Pietropaolo, A.; Andreani, C.; Senesi, R.; Gorini, G.; Perelli-Cippo, E.; Tardocchi, M. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX (United Kingdom); Consiglio Nazionale delle Ricerche-Istituto Nazionale per la Fisica della Materia, Universita degli Studi di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome (Italy); Dipartimento di Fisica, Universita degli Studi di Roma 'Tor Vergata', Via della Ricerca Scientifica 1, 00133 Rome (Italy); Dipartimento di Fisica 'G. Occhialini', Universita degli Studi di Milano Bicocca, Piazza della Scienza 2, I-20126 Milan (Italy) and CNR-INFM, Universita degli Studi di Milano Bicocca, Piazza della Scienza 2, I-20126 Milan (Italy)

2006-09-15

72

Downregulation of Na(+)-NQR complex is essential for Vibrio alginolyticus in resistance to balofloxacin.  

PubMed

Increasingly isolated frequency of antibiotic-resistant V. alginolyticus strains in clinic and aquaculture has been reported, but the mechanisms of V. alginolyticus antibiotic resistance are largely absent. In the present study, native/SDS-PAGE based proteomics, which may provide information on protein-protein interaction, was utilized to investigate differential proteins of V. alginolyticus in resistance to balofloxacin. Ten proteins were altered, in which V12G01_04671, V12G01_00457, V12G01_15927, V12G01_15240, NqrA (spot 26), and NqrF (spot 30) were downregulated, while V12G01_22043, TolC, V12G01_15130, V12G01_19297 were upregulated. Importantly, the two components of Na(+)-NQR complex, NqrA and NqrF, were vertically lined and was further investigated. Western blotting assay indicated that downregulation of the two proteins contrasted sharply with upregulation of a control protein TolC, which was consistent with the result obtained from 2-DE gel analysis. Furthermore, overexpression of NqrA, NqrF and TolC resulted in decrease and elevation of bacterial survival ability in medium with balofloxacin, respectively. These results indicate that downregulation of Na(+)-NQR complex is essential for V. alginolyticus resistance to balofloxacin. This is the first report on the role of Na(+)-NQR complex in antibiotic resistance. This finding highlights the way to an understanding of antibiotic-resistant mechanisms in content of metabolic regulation. PMID:22465713

Li, Peipei; Liu, Xianjie; Li, Hui; Peng, Xuan-Xian

2012-05-17

73

Investigating real-time activation of adenosine receptors by bioluminescence resonance energy transfer technique  

NASA Astrophysics Data System (ADS)

Adenosine receptors play important roles in many physiological and pathological processes, for example regulating myocardial oxygen consumption and the release of neurotransmitters. The activations of adenosine receptors have been studied by some kinds of techniques, such as western blot, immunohistochemistry, etc. However, these techniques cannot reveal the dynamical response of adenosine receptors under stimulation. In this paper, bioluminescence resonance energy transfer technique was introduced to study the real-time activation of adenosine receptors by monitoring the dynamics of cyclic adenosine monophosphate (cAMP) level. The results showed that there were significant differences between adenosine receptors on real-time responses under stimulation. Moreover, the dynamics of cAMP level demonstrated that competition between adenosine receptors existed. Taken together, our study indicates that monitoring the dynamics of cAMP level using bioluminescence resonance energy transfer technique could be one potential approach to investigate the mechanism of competitions between adenosine receptors.

Huang, Yimei; Yang, Hongqin; Zheng, Liqin; Chen, Jiangxu; Wang, Yuhua; Li, Hui; Xie, Shusen

2013-02-01

74

CORDIC algorithm based digital detection technique applied in resonator fiber optic gyroscope  

NASA Astrophysics Data System (ADS)

A digital detection technique based on the coordinate rotation digital computer (CORDIC) algorithm is proposed for a resonator fiber optic gyroscope (R-FOG). It makes the generation of modulation signal, synchronous demodulation and signal processing in R-FOG to be realized in a single field programmable gate array (FPGA). The frequency synthesis and synchronous detection techniques based on the CORDIC algorithm have been analyzed and designed firstly. The experimental results indicate that the precision of the detection circuit satisfies the requirements for the closed-loop feedback in R-FOG system. The frequency of the laser is locked to the resonance frequency of the fiber ring resonator stably and the open-loop gyro output signal is observed successfully. The dynamic range and the bias drift of the R-FOG are ±1.91 rad/s and 0.005 rad/s over 10 s, respectively.

Yang, Zhihuai; Jin, Xiaojun; Ma, Huilian; Jin, Zhonghe

2009-06-01

75

Surface plasmon resonance reflectance imaging technique for near-field (~100 nm) fluidic characterization  

Microsoft Academic Search

Surface plasmon resonance (SPR) reflectance imaging technique is devised as a label-free visualization tools to characterize\\u000a near-field (100 nm) fluidic transport properties. The key idea is that the SPR reflectance intensity varies with the near-field\\u000a refractive index (RI) of the test fluid, which in turn depends on the micro\\/nano-fluidic scalar properties, such as concentrations,\\u000a temperatures, and phases. The SPR sensor techniques

Kenneth D. Kihm

2010-01-01

76

Application of Advanced Magnetic Resonance Imaging Techniques in Evaluation of the Lower Extremity  

PubMed Central

Synopsis This article reviews current magnetic resonance imaging techniques for imaging the lower extremity, focusing on imaging of the knee, ankle, and hip joints. Recent advancements in MRI include imaging at 7 Tesla, using multiple receiver channels, T2* imaging, and metal suppression techniques, allowing more detailed visualization of complex anatomy, evaluation of morphological changes within articular cartilage, and imaging around orthopedic hardware. PMID:23622097

Braun, Hillary J.; Dragoo, Jason L.; Hargreaves, Brian A.; Levenston, Marc E.; Gold, Garry E.

2012-01-01

77

The role of magnetic resonance techniques in understanding and managing multiple sclerosis  

Microsoft Academic Search

Summary Magnetic resonance (MR) techniques have had a major impact in the last 10-15 years in understanding and managing multiple sclerosis. This review summarizes the current uses of MR in multiple sclerosis, based on the proceedings of a recent international workshop, under four headings: (i) technical issues; (ii) role in diagnosis; (iii) natural history studies in understanding the disease; (iv)

D. H. Miller; R. I. Grossman; S. C. Reingold; H. F. McFarland

1998-01-01

78

Evidence for low-temperature internal dynamics in Cu 12As 4S 13 according to copper NQR and nuclear relaxation  

NASA Astrophysics Data System (ADS)

63,65Cu nuclear quadrupole resonance (NQR) was applied to study the natural mineral Cu 12As 4S 13 (tennantite) in the temperature range 4.2-210 K. The obtained results point to the presence of field fluctuations caused by internal motions in tennantite. Consistently with the crystal structure, the experimental data can be described by an occurrence of a magnetic phase transition, which takes place near 65 K. The low-temperature phase is characterized by Cu(II) electron magnetic moments freezing in the form of a spin-glass-like constitution.

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

2006-12-01

79

Monitoring cell adhesion processes on bioactive polymers with the quartz crystal resonator technique.  

PubMed

The Thickness Shear Mode (TSM) quartz crystal resonator has been extensively used as sensitive sensor in various electrochemical and biological applications. This technique based on the propagation of an ultrasonic shear wave generated by a sinusoidal electric field through a piezoelectric quartz resonator, provides a non-destructive and powerful means to probe changes at solid-solid or solid-liquid interfaces. In this study, TSM was used to characterize cell-polymer interactions developing during the cell adhesion process. TSM sensing was used to monitor the inhibiting properties of bioactive polymers towards fibroblast McCoy adhesion processes. For this purpose, thin films of various bioactive polymers exhibiting either carboxylate or/and sulfonate functional groups were deposited onto the TSM. Measurements of the time variation of the electrical motional resistance in the vicinity of the mechanical sensor resonant frequency were performed as the quartz crystal resonator was either coated with the continuous polymer phase or polymer plus cell suspensions. Cell adhesion processes on these surfaces was investigated by cell counting and the quartz resonator-based technique. Inhibition of fibroblast McCoy adhesion onto thin polymer films of various chemical compositions was analyzed and discussed in the perspective of a possible application of these bioactive polymers to fabricate intraocular lenses able to prevent secondary cataract phenomena. PMID:15664647

Le Guillou-Buffello, Delphine; Hélary, Gérard; Gindre, Marcel; Pavon-Djavid, Graciela; Laugier, Pascal; Migonney, Véronique

2005-07-01

80

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

81

On the Efficiency of Application of Quasi-Optical Resonator Technique to Investigation of the Electrophysical Properties of Materials  

NASA Astrophysics Data System (ADS)

Sensitivities of waveguide and resonator techniques of fixing small changes in the modulus of the reflection or transmission coefficient of the examined material are compared. Conditions are determined under which the resonator technique has essential advantage of the maximum sensitivity to small variations of the object parameters.

Dorofeev, I. O.; Dunaevskii, G. E.

2015-02-01

82

An efficient technique for the reduction of wavelength noise in resonance-based integrated photonic sensors.  

PubMed

A systematic study of the limit of detection (LOD) in resonance-based silicon photonic lab-on-chip sensors is presented. The effects of the noise, temperature fluctuations, and the fundamental thermodynamic limit of the resonator are studied. Wavelength noise is identified as the dominant source of noise, and an efficient technique for suppressing this noise is presented. A large ensemble of statistical data from the transmission measurements in a laser-scanning configuration on five silicon nitride (SiN) microrings is collected to discuss and identify the sources of noise. The experimental results show that the LOD is limited by a 3? wavelength noise of ?1.8 pm. We present a sub-periodic interferometric technique, relying on an inverse algorithm, to suppress this noise. Our technique reduces the wavelength noise by more than one order of magnitude to an ensemble average of 3? = 120 fm, for a resonator quality factor (Q) of about 5 × 10(4) without any temperature stabilization or cooling. This technique is readily amenable to on-chip integration to realize highly accurate and low-cost lab-on-chip sensors. PMID:25243248

Ghasemi, Farshid; Chamanzar, Maysamreza; Eftekhar, Ali A; Adibi, Ali

2014-11-21

83

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

84

Resonance frequencies and Young's modulus determination of magnetorheological elastomers using the photoacoustic technique  

NASA Astrophysics Data System (ADS)

A simple and reliable methodology for determining the Young's modulus of magnetorheological elastomers is proposed based on the resonance frequencies of the amplitude of the photoacoustic signal. An explicit expression for the pressure changes within a photoacoustic cell, due to the thermal expansion of the air and the elastic bending of a clamped circular elastic membrane, is derived and analyzed. It is found that the resonance behavior of the amplitude of the photoacoustic signal is due to the contribution of the axial bending of its thickness. It is also shown that the Young's modulus of the membrane is proportional to its density, the square of its resonance frequencies and the fourth power of its radius, and inversely proportional to the square of its thickness. The application of the proposed approach to membranes made up of spherical microparticles of carbonyl iron powder embedded in a matrix of silicone rubber with weight concentrations of 0%, 5.2%, and 13.7% yields accurate and reproducible results, which are in good agreement with reported data in the literature. The highest accuracy on the measurement of the resonance frequencies and therefore on the Young's modulus is found for the first resonance peak. When a magnetic field is applied to the samples to modify their stiffness, it is observed that the Young's modulus increases with the magnetic field. This novel application of the photoacoustic technique opens the possibility of performing mechanical characterization of a broad diversity of magnetorheological membranes.

Daniel Macias, J.; Ordonez-Miranda, J.; Alvarado-Gil, J. J.

2012-12-01

85

Extracting Information about the Rotator Cuff from Magnetic Resonance Images Using Deterministic and Random Techniques  

PubMed Central

We consider some methods to extract information about the rotator cuff based on magnetic resonance images; the study aims to define an alternative method of display that might facilitate the detection of partial tears in the supraspinatus tendon. Specifically, we are going to use families of ellipsoidal triangular patches to cover the humerus head near the affected area. These patches are going to be textured and displayed with the information of the magnetic resonance images using the trilinear interpolation technique. For the generation of points to texture each patch, we propose a new method that guarantees the uniform distribution of its points using a random statistical method. Its computational cost, defined as the average computing time to generate a fixed number of points, is significantly lower as compared with deterministic and other standard statistical techniques. PMID:25650281

De Los Ríos, F. A.; Paluszny, M.

2015-01-01

86

Extracting information about the rotator cuff from magnetic resonance images using deterministic and random techniques.  

PubMed

We consider some methods to extract information about the rotator cuff based on magnetic resonance images; the study aims to define an alternative method of display that might facilitate the detection of partial tears in the supraspinatus tendon. Specifically, we are going to use families of ellipsoidal triangular patches to cover the humerus head near the affected area. These patches are going to be textured and displayed with the information of the magnetic resonance images using the trilinear interpolation technique. For the generation of points to texture each patch, we propose a new method that guarantees the uniform distribution of its points using a random statistical method. Its computational cost, defined as the average computing time to generate a fixed number of points, is significantly lower as compared with deterministic and other standard statistical techniques. PMID:25650281

De Los Ríos, F A; Paluszny, M

2015-01-01

87

High efficiency resonance ionization mass spectrometric analysis by external laser cavity enhancement techniques  

SciTech Connect

The demand to measure high dynamic range isotope ratios on small samples with resonance ionization mass spectrometry (RIMS) continues to increase. This paper discusses high ionization efficiency methods which can be applied to continuous wave (cw) RIMS to potentially achieve several tens of percent ionization efficiencies for certain elements. The primary technique under development to achieve this is an external laser cavity which can generate very high circulating laser powers. 12 refs., 3 figs.

Johnson, S.G.; Rios, E.L.; Miller, C.M.; Fearey, B.L.

1991-01-01

88

Surface resistance of superconducting films by a microstrip ring resonator technique  

Microsoft Academic Search

A ring microstrip resonator technique has been set up to measure the surface impedance of superconducting films in the range 1-20 GHz as a function of temperature and both DC and RF field amplitude. The method has been tested on Nb films and extended to both metallic compounds of interest for thin-film-coated accelerating cavity applications (NbTiN) and high Tc oxide

A. Andreone; A. DiChiara; G. Peluso; C. Attanasio; L. Maritato; S. Marra; R. Vaglio; E. Milani; M. Montuori

1993-01-01

89

A DC-AC Power Conversion Technique Using Twin Resonant High-Frequency Links  

Microsoft Academic Search

The advantages of load commUtated high-frequency (HF) sinusoidal inverters as link stiiges in power conversion are well-known. An inverter configuration that employs parallel connection of the load to the resonating capacitor can be employed to realize the high- frequency link. A technique of dc to low-frequency ac power conversion using two, such high-fre4uency links is presented. The frequencies of the

V. T. Ranganathan; Phoivos D. Ziogas

1983-01-01

90

Dynamic neutron scattering on incoherent systems using efficient resonance spin flip techniques  

SciTech Connect

We have performed numerical ray-tracing Monte-Carlo-simulations of incoherent dynamic neutron scattering experiments. We intend to optimize the efficiency of incoherent measurements depending on the fraction of neutrons scattered without and with spin flip at the sample. In addition to conventional spin echo, we have numerically and experimentally studied oscillating intensity techniques. The results point out the advantages of these different spin echo variants and are an important prerequisite for neutron resonance spin echo instruments like RESEDA (FRM II, Munich), to choose the most efficient technique depending on the scattering vector range and the properties of the sample system under study.

Häussler, Wolfgang [Heinz Maier-Leibnitz Zentrum, Technische Universität München, D-85748 Garching, Germany and Physik-Department E21, Technische Universität München, D-85748 Garching (Germany); Kredler, Lukas [Physik-Department E21, Technische Universität München, D-85748 Garching (Germany)

2014-05-15

91

Coexistence of multiple charge-density waves and superconductivity in SrPt2As2 revealed by 75As-NMR /NQR and 195Pt-NMR  

NASA Astrophysics Data System (ADS)

The relationship between charge-density wave (CDW) orders and superconductivity in arsenide superconductor SrPt2As2 with Tc=5.2 K which crystallizes in the CaBe2Ge2 -type structure was studied by 75As nuclear magnetic resonance (NMR) measurements up to 520 K, and 75As nuclear quadrupole resonance (NQR) and 195Pt-NMR measurements down to 1.5 K. At high temperature, 75As-NMR spectrum and nuclear-spin-relaxation rate (1 /T1) have revealed two distinct CDW orders, one realized in the As-Pt-As layer below TCDWAs (1 )=410 K and the other in the Pt-As-Pt layer below TCDWAs (2 )=255 K . The 1 /T1 measured by 75As-NQR shows a clear Hebel-Slichter peak just below Tc and decreases exponentially well below Tc. Concomitantly, 195Pt Knight shift decreases below Tc. Our results indicate that superconductivity in SrPt2As2 is in the spin-singlet state with an s -wave gap and is robust under the two distinct CDW orders in different layers.

Kawasaki, Shinji; Tani, Yoshihiko; Mabuchi, Tomosuke; Kudo, Kazutaka; Nishikubo, Yoshihiro; Mitsuoka, Daisuke; Nohara, Minoru; Zheng, Guo-qing

2015-02-01

92

Localization and Function of the Membrane-bound Riboflavin in the Na+-translocating NADH:Quinone Oxidoreductase (Na+-NQR) from Vibrio cholerae*  

PubMed Central

The sodium ion-translocating NADH:quinone oxidoreductase (Na+-NQR) from the human pathogen Vibrio cholerae is a respiratory membrane protein complex that couples the oxidation of NADH to the transport of Na+ across the bacterial membrane. The Na+-NQR comprises the six subunits NqrABCDEF, but the stoichiometry and arrangement of these subunits are unknown. Redox-active cofactors are FAD and a 2Fe-2S cluster on NqrF, covalently attached FMNs on NqrB and NqrC, and riboflavin and ubiquinone-8 with unknown localization in the complex. By analyzing the cofactor content and NADH oxidation activity of subcomplexes of the Na+-NQR lacking individual subunits, the riboflavin cofactor was unequivocally assigned to the membrane-bound NqrB subunit. Quantitative analysis of the N-terminal amino acids of the holo-complex revealed that NqrB is present in a single copy in the holo-complex. It is concluded that the hydrophobic NqrB harbors one riboflavin in addition to its covalently attached FMN. The catalytic role of two flavins in subunit NqrB during the reduction of ubiquinone to ubiquinol by the Na+-NQR is discussed. PMID:20558724

Casutt, Marco S.; Huber, Tamara; Brunisholz, René; Tao, Minli; Fritz, Günter; Steuber, Julia

2010-01-01

93

Pulsed Bromine-81 Nuclear Quadrupole Resonance Spectroscopy of Brominated Flame Retardants and Associated Polymer Blends.  

NASA Astrophysics Data System (ADS)

The dispersion of brominated flame retardants in polymers is monitored with bromine-81 NQR using a pulse NQR spectrometer. The NQR spectrometer consists of a homemade 10-300 MHz single-channel NMR console coupled to a broadly tunable probe. The probe is a loop-gap resonator usable from 220 to 300 MHz, and automatically tuned over any 5 MHz region with a stepping motor and an RF bidirectional coupler. Bromine-81 NQR spectra of several brominated aromatic flame retardants, as pure materials and in polymers, were recorded in the range of 227 to 256 MHz in zero applied magnetic field. Two factors affect the bromine-79/81 NQR transition frequencies in brominated aromatics: electron withdrawing substituents on the ring and intermolecular contacts with other bromine atoms in the crystal structure. An existing model for substituents is updated and a point charge model for the intermolecular contacts is developed. In this study, we exploit the bromine-81 NQR transition frequency dependence on intermolecular contacts to learn how a flame retardant is dispersed in a polymer matrix.

Mrse, Anthony A.; Lee, Youngil; Bryant, Pamela L.; Fronczek, Frank R.; Butler, Leslie G.; Simeral, Larry S.

1998-03-01

94

A biofilm microreactor system for simultaneous electrochemical and nuclear magnetic resonance techniques.  

PubMed

Nuclear magnetic resonance (NMR) techniques are ideally suited for the study of biofilms and for probing their microenvironments because these techniques allow for noninvasive interrogation and in situ monitoring with high resolution. By combining NMR with simultaneous electrochemical techniques, it is possible to sustain and study live biofilms respiring on electrodes. Here, we describe a biofilm microreactor system, including a reusable and a disposable reactor, that allows for simultaneous electrochemical and NMR techniques (EC-NMR) at the microscale. Microreactors were designed with custom radio frequency resonator coils, which allowed for NMR measurements of biofilms growing on polarized gold electrodes. For an example application of this system we grew Geobacter sulfurreducens biofilms on electrodes. EC-NMR was used to investigate growth medium flow velocities and depth-resolved acetate concentration inside the biofilm. As a novel contribution we used Monte Carlo error analysis to estimate the standard deviations of the acetate concentration measurements. Overall, we found that the disposable EC-NMR microreactor provided a 9.7 times better signal-to-noise ratio over the reusable reactor. The EC-NMR biofilm microreactor system can ultimately be used to correlate extracellular electron transfer rates with metabolic reactions and explore extracellular electron transfer mechanisms. PMID:24622544

Renslow, R S; Babauta, J T; Majors, P D; Mehta, H S; Ewing, R J; Ewing, T W; Mueller, K T; Beyenal, H

2014-01-01

95

A biofilm microreactor system for simultaneous electrochemical and nuclear magnetic resonance techniques  

SciTech Connect

In order to fully understand electrochemically active biofilms and the limitations to their scale-up in industrial biofilm reactors, a complete picture of the microenvironments inside the biofilm is needed. Nuclear magnetic resonance (NMR) techniques are ideally suited for the study of biofilms and for probing their microenvironments because these techniques allow for non-invasive interrogation and in situ monitoring with high resolution. By combining NMR with simultaneous electrochemical techniques, it is possible to sustain and study live electrochemically active biofilms. Here, we introduce a novel biofilm microreactor system that allows for simultaneous electrochemical and NMR techniques (EC-NMR) at the microscale. Microreactors were designed with custom radiofrequency resonator coils, which allowed for NMR measurements of biofilms growing on polarized gold electrodes. For an example application of this system, we grew Geobacter sulfurreducens biofilms. NMR was used to investigate growth media flow velocities, which were compared to simulated laminar flow, and electron donor concentrations inside the biofilms. We use Monte Carlo error analysis to estimate standard deviations of the electron donor concentration measurements within the biofilm. The EC-NMR biofilm microreactor system can ultimately be used to correlate extracellular electron transfer rates with metabolic reactions and explore extracellular electron transfer mechanisms.

Renslow, Ryan S.; Babauta, Jerome T.; Majors, Paul D.; Mehta, Hardeep S.; Ewing, R. James; Ewing, Thomas; Mueller, Karl T.; Beyenal, Haluk

2014-03-01

96

Microwave heating and dielectric diagnosis technique in a single-mode resonant cavity  

NASA Astrophysics Data System (ADS)

A single-mode microwave heating and dielectric measurement technique has been developed. The single- and swept-frequency methods were used to simultaneously heat the material and measure its complex permittivity in this single-mode technique. A cylindrical cavity and Nylon 66 rods were used in this study. The cavity was always resonated in the TM012-mode at 2.45 GHz. The measured changes in the resonant frequency and cavity Q factor of the cavity with and without the sample were related to complex permittivity of the sample using material-cavity perturbation. Temperature measurement was made using a fluoroptic thermometer. On-line measurements of complex permittivity and temperature were made during single- and swept-frequency microwave heating of the sample. Complex permittivity of Nylon 66 as a function of temperature using the single-frequency method was compared to that using the conventional swept-frequency method during microwave heating. It shows that dielectric measurements using the single- and swept-frequency methods are repeatable and consistent. However, the resolution in resonant frequency shifts and cavity Q factor measurements is higher in the single-frequency method. The measurement errors for permittivity and dielectric loss factor are less than ±4% and ±10% for the single-frequency method and less than ±5% and ±15% for the swept-frequency method. Therefore, the single-frequency method is more accurate than the swept-frequency method.

Jow, Jinder; Hawley, Martin C.; Finzel, Mark C.; Asmussen, Jes, Jr.

1989-01-01

97

Vibrational techniques applied to photosynthesis: Resonance Raman and fluorescence line-narrowing.  

PubMed

Resonance Raman spectroscopy may yield precise information on the conformation of, and the interactions assumed by, the chromophores involved in the first steps of the photosynthetic process. Selectivity is achieved via resonance with the absorption transition of the chromophore of interest. Fluorescence line-narrowing spectroscopy is a complementary technique, in that it provides the same level of information (structure, conformation, interactions), but in this case for the emitting pigment(s) only (whether isolated or in an ensemble of interacting chromophores). The selectivity provided by these vibrational techniques allows for the analysis of pigment molecules not only when they are isolated in solvents, but also when embedded in soluble or membrane proteins and even, as shown recently, in vivo. They can be used, for instance, to relate the electronic properties of these pigment molecules to their structure and/or the physical properties of their environment. These techniques are even able to follow subtle changes in chromophore conformation associated with regulatory processes. After a short introduction to the physical principles that govern resonance Raman and fluorescence line-narrowing spectroscopies, the information content of the vibrational spectra of chlorophyll and carotenoid molecules is described in this article, together with the experiments which helped in determining which structural parameter(s) each vibrational band is sensitive to. A selection of applications is then presented, in order to illustrate how these techniques have been used in the field of photosynthesis, and what type of information has been obtained. This article is part of a Special Issue entitled: Vibrational spectroscopies and bioenergetic systems. PMID:25268562

Gall, Andrew; Pascal, Andrew A; Robert, Bruno

2015-01-01

98

Quantitative linear and nonlinear resonant inspection techniques for characterizing thermal damage in  

E-print Network

on linear resonant ultrasound spectroscopy, numerical simulations and nonlinear resonant ultrasound]. Resonant Ultrasound Spectroscopy (RUS) allows the material elastic properties to be determined accurately to determine their linear characteristics. Nonlinear Resonance Ultrasound Spectroscopy (NRUS) was developed

Paris-Sud XI, Université de

99

Direct imaging of neural currents using ultra-low field magnetic resonance techniques  

DOEpatents

Using resonant interactions to directly and tomographically image neural activity in the human brain using magnetic resonance imaging (MRI) techniques at ultra-low field (ULF), the present inventors have established an approach that is sensitive to magnetic field distributions local to the spin population in cortex at the Larmor frequency of the measurement field. Because the Larmor frequency can be readily manipulated (through varying B.sub.m), one can also envision using ULF-DNI to image the frequency distribution of the local fields in cortex. Such information, taken together with simultaneous acquisition of MEG and ULF-NMR signals, enables non-invasive exploration of the correlation between local fields induced by neural activity in cortex and more `distant` measures of brain activity such as MEG and EEG.

Volegov, Petr L. (Los Alamos, NM); Matlashov, Andrei N. (Los Alamos, NM); Mosher, John C. (Los Alamos, NM); Espy, Michelle A. (Los Alamos, NM); Kraus, Jr., Robert H. (Los Alamos, NM)

2009-08-11

100

Review of pyroelectric thermal energy harvesting and new MEMs based resonant energy conversion techniques  

SciTech Connect

Harvesting electrical energy from thermal energy sources using pyroelectric conversion techniques has been under investigation for over 50 years, but it has not received the attention that thermoelectric energy harvesting techniques have during this time period. This lack of interest stems from early studies which found that the energy conversion efficiencies achievable using pyroelectric materials were several times less than those potentially achievable with thermoelectrics. More recent modeling and experimental studies have shown that pyroelectric techniques can be cost competitive with thermoelectrics and, using new temperature cycling techniques, has the potential to be several times as efficient as thermoelectrics under comparable operating conditions. This paper will review the recent history in this field and describe the techniques that are being developed to increase the opportunities for pyroelectric energy harvesting. The development of a new thermal energy harvester concept, based on temperature cycled pyroelectric thermal-to-electrical energy conversion, are also outlined. The approach uses a resonantly driven, pyroelectric capacitive bimorph cantilever structure that can be used to rapidly cycle the temperature in the energy harvester. The device has been modeled using a finite element multi-physics based method, where the effect of the structure material properties and system parameters on the frequency and magnitude of temperature cycling, and the efficiency of energy recycling using the proposed structure, have been modeled. Results show that thermal contact conductance and heat source temperature differences play key roles in dominating the cantilever resonant frequency and efficiency of the energy conversion technique. This paper outlines the modeling, fabrication and testing of cantilever and pyroelectric structures and single element devices that demonstrate the potential of this technology for the development of high efficiency thermal-to-electrical energy conversion devices.

Hunter, Scott Robert [ORNL; Lavrik, Nickolay V [ORNL; Mostafa, Salwa [ORNL; Rajic, Slobodan [ORNL; Datskos, Panos G [ORNL

2012-01-01

101

A Second Look at Neutron Resonance Transmission Analysis as a Spent Fuel NDA Technique  

SciTech Connect

Many different nondestructive analysis techniques are currently being investigated as a part of the United States Department of Energy's Next Generation Safeguards Initiative (NGSI) seeking methods to quantify plutonium in spent fuel. Neutron Resonance Transmission Analysis (NRTA) is one of these techniques. Having first been explored in the mid-1970s for the analysis of individual spent-fuel pins a second look, using advanced simulation and modeling methods, is now underway to investigate the suitability of the NRTA technique for assaying complete spent nuclear fuel assemblies. The technique is similar to neutron time-of-flight methods used for cross-section determinations but operates over only the narrow 0.1-20 eV range where strong, distinguishable resonances exist for both the plutonium (239, 240, 241,242Pu) and uranium (235,236,238U) isotopes of interest in spent fuel. Additionally, in this energy range resonances exists for six important fission products (99Tc, 103Rh, 131Xe, 133Cs, 145Nd, and 152Sm) which provide additional information to support spent fuel plutonium assay determinations. Initial modeling shows excellent agreement with previously published experimental data for measurements of individual spent-fuel pins where plutonium assays were demonstrated to have a precision of 2-4%. Within the simulation and modeling analyses of this project scoping studies have explored fourteen different aspects of the technique including the neutron source, drift tube configurations, and gross neutron transmission as well as the impacts of fuel burn up, cooling time, and fission-product interferences. These results show that NRTA may be a very capable experimental technique for spent-fuel assay measurements. The results suggest sufficient transmission strength and signal differentiability is possible for assays through up to 8 pins. For an 8-pin assay (looking at an assembly diagonally), 64% of the pins in a typical 17 ? 17 array of a pressurized water reactor fuel assembly can be part of a complete transmission assay measurement with high precision. Analysis of rows with up to 12 pins may also be feasible but with diminished precision. Preliminary data analysis of an NRTA simulation has demonstrated the simplicity of the technique.

James W .Sterbentz; David L. Chichester

2011-07-01

102

[Magnetic resonance imaging postprocessing techniques in the study of brain connectivity].  

PubMed

Brain connectivity is a key concept for understanding brain function. Current methods to detect and quantify different types of connectivity with neuroimaging techniques are fundamental for understanding the pathophysiology of many neurologic and psychiatric disorders. This article aims to present a critical review of the magnetic resonance imaging techniques used to measure brain connectivity within the context of the Human Connectome Project. We review techniques used to measure: a) structural connectivity b) functional connectivity (main component analysis, independent component analysis, seed voxel, meta-analysis), and c) effective connectivity (psychophysiological interactions, causal dynamic models, multivariate autoregressive models, and structural equation models). These three approaches make it possible to combine and use different statistical techniques to elaborate mathematical models in the attempt to understand the functioning of the brain. The findings obtained with these techniques must be validated by other techniques for analyzing structural and functional connectivity. This information is integrated in the Human Connectome Project where all these approaches converge to provide a representation of all the different models of connectivity. PMID:21477826

de la Iglesia-Vayá, M; Molina-Mateo, J; Escarti-Fabra, M J; Martí-Bonmatí, L; Robles, M; Meneu, T; Aguilar, E J; Sanjuán, J

2011-01-01

103

Development of techniques in magnetic resonance and structural studies of the prion protein  

SciTech Connect

Magnetic resonance is the most powerful analytical tool used by chemists today. Its applications range from determining structures of large biomolecules to imaging of human brains. Nevertheless, magnetic resonance remains a relatively young field, in which many techniques are currently being developed that have broad applications. In this dissertation, two new techniques are presented, one that enables the determination of torsion angles in solid-state peptides and proteins, and another that involves imaging of heterogenous materials at ultra-low magnetic fields. In addition, structural studies of the prion protein via solid-state NMR are described. More specifically, work is presented in which the dependence of chemical shifts on local molecular structure is used to predict chemical shift tensors in solid-state peptides with theoretical ab initio surfaces. These predictions are then used to determine the backbone dihedral angles in peptides. This method utilizes the theoretical chemicalshift tensors and experimentally determined chemical-shift anisotropies (CSAs) to predict the backbone and side chain torsion angles in alanine, leucine, and valine residues. Additionally, structural studies of prion protein fragments are described in which conformationally-dependent chemical-shift measurements were made to gain insight into the structural differences between the various conformational states of the prion protein. These studies are of biological and pathological interest since conformational changes in the prion protein are believed to cause prion diseases. Finally, an ultra-low field magnetic resonance imaging technique is described that enables imaging and characterization of heterogeneous and porous media. The notion of imaging gases at ultra-low fields would appear to be very difficult due to the prohibitively low polarization and spin densities as well as the low sensitivities of conventional Faraday coil detectors. However, Chapter 5 describes how gas imaging at ultra-low fields is realized by incorporating the high sensitivities of a dc superconducting quantum interference device (SQUID) with the high polarizations attainable through optica11y pumping {sup 129}Xe gas.

Bitter, Hans-Marcus L.

2000-07-01

104

Reduction of reset pulse in resonant frequency servo loop for resonant fiber-optic gyro by an auto-controlled reset technique.  

PubMed

Resonant fiber-optic gyro (RFOG) based on the Sagnac effect has the potential to achieve the inertial navigation system requirement with a short sensing coil. A high-accuracy resonant frequency servo loop is indispensable for a high-performance RFOG. A digital proportional-integral (PI) controller is always adopted in the resonant frequency servo loop. The resonant frequency of the optical fiber ring resonator drifts with environmental temperature changes. When the resonant frequency drift is beyond the tracking range of the resonant frequency servo loop, the digital PI controller overflows and outputs a reset signal. A large reset pulse, which is equivalent to a rotation rate error of 26°/h, has been observed at the output of the RFOG, while a long time is required for returning to the lock-in state simultaneously. To reduce the effect of the overflow resetting in the digital PI controller, an auto-controlled reset technique is proposed and experimentally demonstrated. As a result, the time for returning to the lock-in state is reduced to 5 ms from 8 s. With the integration time of 1 s, the equivalent accuracy of the resonant frequency servo loop is improved to 0.18°/h. PMID:24513942

Ma, Huilian; Lu, Xiao; Jin, Zhonghe

2013-12-20

105

Magnetic resonance imaging of multiple sclerosis: a study of pulse-technique efficacy  

SciTech Connect

Forty-two patients with the clinical diagnosis of multiple sclerosis were examined by proton magnetic resonance imaging (MRI) at 0.5 T. An extensive protocol was used to facilitate a comparison of the efficacy of different pulse techniques. Results were also compared in 39 cases with high-resolution x-ray computed tomography (CT). MRI revealed characteristic abnormalities in each case, whereas CT was positive in only 15 of 33 patients. Cerebral abnormalities were best shown with the T2-weighted spin-echo sequence: brainstem lesions were best defined on the inversion-recovery sequence.

Runge, V.M.; Price, A.C.; Kirshner, H.S.; Allen, J.H.; Partain, C.L.; James, A.E. Jr.

1984-11-01

106

Magnetic resonance enterography in Crohn’s disease: Standard and advanced techniques  

PubMed Central

Crohn’s disease (CD) is a chronic autoimmune disorder that affects mainly young people. The clinical management is based on the Crohn’s Disease Activity Index and especially on biologic parameters with or without additional endoscopic and imaging procedures, such as barium and computed tomography examinations. Recently, magnetic resonance (MR) imaging has been a promising diagnostic radiologic technique with lack of ionizing radiation, enabling superior tissue contrast resolution due to new pulse-sequence developments. Therefore, MR enterography has the potential to become the modality of choice for imaging the small bowel in CD patients. PMID:21160577

Kayhan, Arda; Oommen, Jacob; Dahi, Farid; Oto, Aytekin

2010-01-01

107

Suppression of electron correlations in the collapsed tetragonal phase of CaFe2As2 under ambient pressure demonstrated by As75 NMR/NQR measurements  

SciTech Connect

The static and the dynamic spin correlations in the low-temperature collapsed tetragonal and the high-temperature tetragonal phase in CaFe2As2 have been investigated by As75 nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements. Through the temperature (T) dependence of the nuclear spin lattice relaxation rates (1/T1) and the Knight shifts, although stripe-type antiferromagnetic (AFM) spin correlations are realized in the high-temperature tetragonal phase, no trace of the AFM spin correlations can be found in the nonsuperconducting, low-temperature, collapsed tetragonal (cT) phase. Given that there is no magnetic broadening in As75 NMR spectra, together with the T-independent behavior of magnetic susceptibility ? and the T dependence of 1/T1T?, we conclude that Fe spin correlations are completely quenched statically and dynamically in the nonsuperconducting cT phase in CaFe2As2.

Furukawa, Yuji [Ames Laboratory; Roy, Beas [Ames Laboratory; Ran, Sheng [Ames Laboratory; Budko, Sergey L. [Ames Laboratory; Canfield, Paul C. [Ames Laboratory

2014-03-20

108

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

109

Density functional calculations of 14N and 11B NQR parameters in the H-capped (6,0) and (4,4) single-walled BN nanotubes  

NASA Astrophysics Data System (ADS)

Density functional theory (DFT) calculations were performed to calculate nitrogen-14 and boron-11 nuclear quadrupole resonance (NQR) spectroscopy parameters in the representative considered models of zigzag and armchair boron nitride nanotubes (BNNTs) for the first time. The considered models consisting of 1 nm length of H-capped (6,0) and (4,4) single-walled BNNT were first allowed to fully relax and then the NQR calculations were performed on the geometrically optimized models. The evaluated nuclear quadrupole coupling constants and asymmetry parameters for the mentioned nuclei reveal that the considered models can be divided into four layers of nuclei with an equivalent electrostatic environment where those nuclei at the ends of tubes have a very strong electrostatic environment compared to the other nuclei along the length of tubes. Those nuclei at the center of the tube length also have an equivalent electrostatic environment. The calculations were performed based on the B3LYP DFT method and 6-311G** and 6-311++G** standard basis sets using the Gaussian 98 package of program.

Mirzaei, Mahmoud; Hadipour, Nasser L.

2008-02-01

110

Dimensional characterization of a quasispherical resonator by microwave and coordinate measurement techniques  

NASA Astrophysics Data System (ADS)

We describe the dimensional characterization of copper quasisphere NPL-Cranfield 2. The quasisphere is assembled from two hemispheres such that the internal shape is a triaxial ellipsoid, the major axes of which have nominal radii 62.000 mm, 62.031 mm and 62.062 mm. The artefact has been manufactured using diamond-turning technology and shows a deviation from design form of less than ±1 µm over most of its surface. Our characterization involves both coordinate measuring machine (CMM) experiments and microwave resonance spectroscopy. We have sought to reduce the dimensional uncertainty below the maximum permissible error of the CMM by comparative measurements with silicon and Zerodur spheres of known volume. Using this technique we determined the equivalent radius with an uncertainty of u(k = 1) = 114 nm, a fractional uncertainty of 1.8 parts in 106. Due to anisotropy of the probe response, we could only determine the eccentricities of the quasihemispheres with a fractional uncertainty of approximately 2%. Our microwave characterization uses the TM11 to TM18 resonances. We find the equivalent radius inferred from analysis of these modes to be consistent within ±4 nm with an overall uncertainty u(k = 1) = 11 nm. We discuss corrections for surface conductivity, waveguide perturbations and dielectric surface layers. We find that the CMM radius estimates derived from each hemisphere cannot be used to accurately predict the equivalent radius of the assembled resonator for two reasons. Firstly, the equatorial flanges are flat only to within ±1 µm, leading to an equatorial 'gap' whose dimension cannot be reliably estimated. Secondly, the resonator undergoes significant elastic distortion when the bolts connecting the hemispheres are tightened. We provide CMM and microwave measurements to support these conclusions in addition to finite-element modelling. Finally, we consider the implications of this work on a forthcoming experiment to determine the Boltzmann constant with a relative uncertainty below 1 part in 106.

Underwood, R.; Flack, D.; Morantz, P.; Sutton, G.; Shore, P.; de Podesta, M.

2011-02-01

111

Biochemical component identification by light scattering techniques in whispering gallery mode optical resonance based sensor  

NASA Astrophysics Data System (ADS)

Experimental data on detection and identification of variety of biochemical agents, such as proteins (albumin, interferon, C reactive protein), microelements (Na+, Ca+), antibiotic of different generations, in both single and multi component solutions under varied in wide range concentration are represented. Analysis has been performed on the light scattering parameters of whispering gallery mode (WGM) optical resonance based sensor with dielectric microspheres from glass and PMMA as sensitive elements fixed by spin - coating techniques in adhesive layer on the surface of substrate or directly on the coupling element. Sensitive layer was integrated into developed fluidic cell with a digital syringe. Light from tuneable laser strict focusing on and scattered by the single microsphere was detected by a CMOS camera. The image was filtered for noise reduction and integrated on two coordinates for evaluation of integrated energy of a measured signal. As the entrance data following signal parameters were used: relative (to a free spectral range) spectral shift of frequency of WGM optical resonance in microsphere and relative efficiency of WGM excitation obtained within a free spectral range which depended on both type and concentration of investigated agents. Multiplexing on parameters and components has been realized using spatial and spectral parameters of scattered by microsphere light with developed data processing. Biochemical component classification and identification of agents under investigation has been performed by network analysis techniques based on probabilistic network and multilayer perceptron. Developed approach is demonstrated to be applicable both for single agent and for multi component biochemical analysis.

Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Saetchnikov, Anton V.; Schweiger, Gustav; Ostendorf, Andreas

2014-03-01

112

Magnetic resonance imaging: Review of imaging techniques and overview of liver imaging  

PubMed Central

Magnetic resonance imaging (MRI) of the liver is slowly transitioning from a problem solving imaging modality to a first line imaging modality for many diseases of the liver. The well established advantages of MRI over other cross sectional imaging modalities may be the basis for this transition. Technological advancements in MRI that focus on producing high quality images and fast imaging, increasing diagnostic accuracy and developing newer function-specific contrast agents are essential in ensuring that MRI succeeds as a first line imaging modality. Newer imaging techniques, such as parallel imaging, are widely utilized to shorten scanning time. Diffusion weighted echo planar imaging, an adaptation from neuroimaging, is fast becoming a routine part of the MRI liver protocol to improve lesion detection and characterization of focal liver lesions. Contrast enhanced dynamic T1 weighted imaging is crucial in complete evaluation of diseases and the merit of this dynamic imaging relies heavily on the appropriate timing of the contrast injection. Newer techniques that include fluoro-triggered contrast enhanced MRI, an adaptation from 3D MRA imaging, are utilized to achieve good bolus timing that will allow for optimum scanning. For accurate interpretation of liver diseases, good understanding of the newer imaging techniques and familiarity with typical imaging features of liver diseases are essential. In this review, MR sequences for a time efficient liver MRI protocol utilizing newer imaging techniques are discussed and an overview of imaging features of selected common focal and diffuse liver diseases are presented. PMID:21160685

Maniam, Santhi; Szklaruk, Janio

2010-01-01

113

ABO Blood-Typing Using an Antibody Array Technique Based on Surface Plasmon Resonance Imaging  

PubMed Central

In this study, readily available antibodies that are used in standard agglutination tests were evaluated for their use in ABO blood typing by a surface plasmon resonance imaging (SPR imaging) technique. Five groups of antibodies, including mixed clones of anti-A, anti-B, and anti-AB, and single clones of anti-A and anti-B, were used to construct the five-line detection arrays using a multichannel flow cell in the SPR imager. The red blood cell (RBC) samples were applied to a multichannel flow cell that was orthogonal to the detection line arrays for blood group typing. We found that the blood samples were correctly grouped in less than 12 min by the SPR imaging technique, and the results were consistent with those of the standard agglutination technique for all 60 samples. We found that mixed clones of antibodies provided 33%–68% greater change in the SPR signal than the single-clone antibodies. Applying the SPR imaging technique using readily available antibodies may reduce the costs of the antibodies, shorten the measurement time, and increase the throughput. PMID:24021965

Houngkamhang, Nongluck; Vongsakulyanon, Apirom; Peungthum, Patjaree; Sudprasert, Krisda; Kitpoka, Pimpun; Kunakorn, Mongkol; Sutapun, Boonsong; Amarit, Ratthasart; Somboonkaew, Armote; Srikhirin, Toemsak

2013-01-01

114

Bone micro-damage assessment using non-linear resonant ultrasound spectroscopy (NRUS) techniques: A feasibility study  

Microsoft Academic Search

Non-linear resonant ultrasound spectroscopy (NRUS) is a technique exploiting the significant non-linear behavior of damaged materials, related to the presence of damage. This study shows for the first time the feasibility of this technique for damage assessment in bone. Two samples of bovine cortical bone were subjected to a progressive damage experiment. Damage accumulation was progressively induced in the samples

M. Muller; J. A. Tencate; T. W. Darling; A. Sutin; R. A. Guyer; M. Talmant; P. Laugier; P. A. Johnson

2006-01-01

115

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

116

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

117

Magnetic resonance urography for the assessment of potential renal donors: comparison of the RARE technique with a low-dose gadolinium-enhanced magnetic resonance urography technique in the absence of pharmacological and mechanical intervention  

Microsoft Academic Search

The aim of this study was to determine whether magnetic resonance urography without pharmacological (diuretic) stimulation and mechanical compression allows conclusive evaluation of the urinary system in potential renal donors. In 28 consecutive patients magnetic resonance urography (MRU) was performed on a 1.5-T system. Two techniques, rapid acquisition with relaxation enhancement (RARE) and a gadolinium (Gd)-enhanced 3D fast low angle

Klaus D. Hagspiel; Sabah Butty; Kiran R. Nandalur; Eric A. Bissonette; Ming-Chen Paul Shih; Daniel A. Leung; J. Fritz Angle; David J. Spinosa; Alan H. Matsumoto; Hossam Ahmed; Hilary Sanfey; Ross B. Isaacs; Robert G. Sawyer; Timothy L. Pruett

2005-01-01

118

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.

119

Three-dimensional electron paramagnetic resonance imaging technique for mapping porosity in ceramics  

SciTech Connect

This paper reports on a three-dimensional (3D) electron paramagnetic resonance imaging (EPRI) method which was developed to probe the structure and size of pores in ceramic materials. The imaging device that was added to the EPR instrument consisted of a computer-controlled current source and magnetic field gradient. This add-on facility was tested using a well-defined diphenlpicrylhydrazzyl phantom sample. Pumice was then used to demonstrate the potential of the technique. This stone was immersed in a 0.5 mm {sup 15}N-substituted per-deutereted tempone water solution to fill the pores with spin labels. Images were reconstructed using a filtered back-projection technique. A two-dimensional (2D) imaging plane was constructed by collecting 33 projection planes over 180 {degrees}. A 3D image was derived from 22 planes each constructed by 22 projections. At present, the facility allows a resolution of 69 and 46 {mu}m for 2D and 3D imaging, respectively. Advancements of the imaging apparatus, software, and line width of the spin labels will be needed to enhance the resolution of this technique.

Kordas, G.; Kang, Y.H. (Science and Technology Center for Cement, Dept. of Materials Science and Engineering, Ceramics Div., Univ. of Illinois at Urbana-Champaign, Urbana, IL (US))

1991-04-01

120

A study of the noncollinear ultrasonic-wave-mixing technique under imperfect resonance conditions.  

PubMed

Geometrical and material property changes cause deviations in the resonant conditions used for noncollinear wave mixing. These deviations are predicted and observed using the SV(?1)+L(?2)?L(?1+?2) interaction, where SV and L are the shear vertical and longitudinal waves, respectively, and ?1, ?2 are their frequencies. Numerical predictions, performed for the scattered secondary field in the far field zone, show three field features of imperfect resonance conditions: (1) rotation of a scattered beam, (2) decrease in the beam amplitude, and (3) beam splitting. The response of the nonlinear ultrasonic wave mixing technique is verified experimentally in two ways: (1) detection of a kissing bond between two polyvinyl chloride (PVC) plates, and (2) detection of subsurface micro-cracks in polymethyl methacrylate (PMMA). A predominant decrease in nonlinear wave energy is observed in both experiments. Beam rotation and splitting is observed in the kissing-bond experiment, while a minor increase in the nonlinear wave energy up to 100% is observed in the micro-cracked PMMA specimen. PMID:25497000

Dem?enko, A; Mainini, L; Korneev, V A

2015-03-01

121

Developing a phase and intensity measurement technique with multiple incident angles under surface plasmon resonance condition  

NASA Astrophysics Data System (ADS)

This work presents the application of a focused beam polarizer-sample-analyzer imaging ellipsometer in measuring the ellipsometric parameters under the surface plasmon resonance condition. By using a cylindrical lens to produce fan shaped beam with multiple incident angles, three-intensity measurement technique can measure the ellipsometric parameters against each incidence but without the need of calibrating the azimuth errors of polarizer and analyzer. As a result of multiple incident angles approach, the whole SPR curve can be obtained without rotating the sensor chip. The intensity and phase response in the air and water interface of the sensor chip were demonstrated, and almost all measured results are close to the theoretical model.

Han, Chien-Yuan; Du, Cheng You; Chen, Yi-Ren; Chao, Yu-Faye

2013-09-01

122

Genomic Plasticity of the rrn-nqrF Intergenic Segment in the Chlamydiaceae?  

PubMed Central

In Chlamydiaceae, the nucleotide sequence between the 5S rRNA gene and the gene for subunit F of the Na+-translocating NADH-quinone reductase (nqrF or dmpP) has varied lengths and gene contents. We analyzed this site in 45 Chlamydiaceae strains having diverse geographical and pathological origins and including members of all nine species. PMID:17158668

Liu, Zhi; Rank, Roger; Kaltenboeck, Bernhard; Magnino, Simone; Dean, Deborah; Burall, Laurel; Plaut, Roger D.; Read, Timothy D.; Myers, Garry; Bavoil, Patrik M.

2007-01-01

123

35Cl NQR spectra of certain chlorine-containing chromium compounds  

NASA Astrophysics Data System (ADS)

The coordination of chlorobenzene to Cr(CO)3 and ClC6H5Cr+ fragments is shown to result in a considerable rise in the NQR frequency of chlorine atoms. The field constant in (chlorobenzene)chromium tricarbonyl was found to grow markedly, relative to pure chlorobenzene.

Kuznetsov, S. I.; Bryukhova, E. V.; Semin, G. K.

2015-03-01

124

Further Evaluation of the Neutron Resonance Transmission Analysis (NRTA) Technique for Assaying Plutonium in Spent Fuel  

SciTech Connect

This is an end-of-year report (Fiscal Year (FY) 2011) for the second year of effort on a project funded by the National Nuclear Security Administration's Office of Nuclear Safeguards (NA-241). The goal of this project is to investigate the feasibility of using Neutron Resonance Transmission Analysis (NRTA) to assay plutonium in commercial light-water-reactor spent fuel. This project is part of a larger research effort within the Next-Generation Safeguards Initiative (NGSI) to evaluate methods for assaying plutonium in spent fuel, the Plutonium Assay Challenge. The second-year goals for this project included: (1) assessing the neutron source strength needed for the NRTA technique, (2) estimating count times, (3) assessing the effect of temperature on the transmitted signal, (4) estimating plutonium content in a spent fuel assembly, (5) providing a preliminary assessment of the neutron detectors, and (6) documenting this work in an end of the year report (this report). Research teams at Los Alamos National Laboratory (LANL), Lawrence Berkeley National Laboratory (LBNL), Pacific Northwest National Laboratory (PNNL), and at several universities are also working to investigate plutonium assay methods for spent-fuel safeguards. While the NRTA technique is well proven in the scientific literature for assaying individual spent fuel pins, it is a newcomer to the current NGSI efforts studying Pu assay method techniques having just started in March 2010; several analytical techniques have been under investigation within this program for two to three years or more. This report summarizes work performed over a nine month period from January-September 2011 and is to be considered a follow-on or add-on report to our previous published summary report from December 2010 (INL/EXT-10-20620).

J. W. Sterbentz; D. L. Chichester

2011-09-01

125

Sedimentary rock porosity studied by electromagnetic techniques: nuclear magnetic resonance and dielectric permittivity  

NASA Astrophysics Data System (ADS)

The present work involves a comprehensive experimental study of porosity and pore size distribution of sedimentary rocks, from oil fields formations, by means of two electromagnetic techniques, namely proton (1H) nuclear magnetic resonance (NMR) and dielectric complex constant (DCC) as function of the frequency, both providing complementary results. The NMR yields an accurate determination of the relative pore size distribution and both movable and irreducible fluids. The DCC measurement provides the direct current electrical resistivity of the samples with different degrees of hydration. Thus, combining the results of both techniques allows the determination of the tortuosity index, by means of Archie's relation, and from it the average pore channel length. These measurements are performed on fully hydrated (saturated), centrifuged, dried, and cleaned rocks and also on samples with the irreducible fluids. Finally, the results are complemented with capillary pressure measurements to obtain the total volume associated with the pore channels related to the rock permeability. Additionally, the work presents a particular method to use a network analyzer to measure the DCC.

Ramia, M. E.; Martín, C. A.

2015-02-01

126

Nanoscale infrared spectroscopy: improving the spectral range of the photothermal induced resonance technique.  

PubMed

Photothermal induced resonance (PTIR) is a new technique which combines the chemical specificity of infrared (IR) spectroscopy with the lateral resolution of atomic force microscopy (AFM). PTIR requires a pulsed tunable laser for sample excitation and an AFM tip to measure the sample expansion induced by light absorption. The limited tunability of commonly available laser sources constrains the application of the PTIR technique to a portion of the IR spectrum. In this work, a broadly tunable pulsed laser relying on a difference frequency generation scheme in a GaSe crystal to emit light tunable from 1.55 ?m to 16 ?m (from 6450 cm(-1) to 625 cm(-1)) was interfaced with a commercial PTIR instrument. The result is a materials characterization platform capable of chemical imaging, in registry with atomic force images, with a spatial resolution that notably surpasses the light diffraction limit throughout the entire mid-IR spectral range. PTIR nanoscale spectra and images allow the identification of compositionally and optically similar yet distinct materials; organic, inorganic, and composite samples can be studied with this nanoscale analog of infrared spectroscopy, suggesting broad applicability. Additionally, we compare the results obtained with the two tunable lasers, which have different pulse lengths, to experimentally assess the recently developed theory of PTIR signal generation. PMID:23363013

Katzenmeyer, Aaron M; Aksyuk, Vladimir; Centrone, Andrea

2013-02-19

127

Focal hepatic lymphoma: magnetic resonance demonstration using current techniques including gadolinium enhancement.  

PubMed

This study demonstrates the appearance of focal hepatic lymphoma using current magnetic resonance techniques including gadolinium enhancement. Fifteen patients with hepatic lymphoma were imaged at 1.5T. T1-weighted, T2-weighted, immediate, and 5-10-min delayed T1-weighted spoiled gradient echo images were acquired in all patients. Determination was made of lesion size, number, morphology, and signal intensity of lesions on all sequences. Seven patients had solitary lesions and 8 patients had multiple lesions. Focal lesions of hepatic lymphoma ranged in size from 5 mm to 15 cm. They were well defined masses with mild to moderate low signal intensity relative to liver on T1-weighted images. Lymphoma lesions in 6 patients were moderately high in signal intensity on T2-weighted images compared with liver (Type I lesions), and enhancement of lesions was intense on early post-gadolinium images in 5 of these patients. Lymphoma lesions in 6 patients were mildly hypointense to mildly hyperintense on T2-weighted images compared to liver (Type II lesions), and lesions in 5 of these patients enhanced minimally on the early post-gadolinium spoiled gradient echo images. The remaining 3 patients had received chemotherapy before the magnetic resonance examination, and the imaging findings varied reflecting presumed differences in treatment responses. Transient ill defined perilesional enhancement on immediate post-gadolinium spoiled gradient echo images was observed in 9 patients including patients with either type of lesion. Focal lesions of hepatic lymphoma are usually low in signal intensity on T1-weighted images but have variable signal intensity on T2-weighted images. In general, lesions that are mildly hypointense to minimally hyperintense in signal intensity on T2-weighted images enhance minimally, and lesions moderately high in signal intensity of T2-weighted images enhance intensely. Transient increased perilesional enhancement is common. PMID:9285802

Kelekis, N L; Semelka, R C; Siegelman, E S; Ascher, S M; Outwater, E K; Woosley, J T; Reinhold, C; Mitchell, D G

1997-01-01

128

Study of a defect detection accuracy of a granite nondestructive resonance technique based on a laser interferometer  

NASA Astrophysics Data System (ADS)

A nondestructive testing technique based on a resonance approach and a laser interferometer device is introduced in the presented paper. It utilizes a not synchronized with an acquisition device and low power excitation source. Induced vibrations are acquired using high resolution laser interferometer in a configuration of a vibrometer. As a result, the test equipment is significantly simplified and tailored to the industry requirements. Sample evaluation process is based on a processing that fits lowest order resonance frequencies to p-wave and s-wave frequencies. Obtained velocities are used to fit higher order resonance frequencies present in the response with positions and lengths of resonators formed by cracks or flaws. Presented research focuses on an assessment of accuracy and sensitivity of the introduced method. Performed measurements revealed that it is possible to obtain decent parameters for industry applications.

Pod?orny, Tomasz; Budzy?, Grzegorz; Rzepka, Janusz; Tkaczyk, Jakub

2014-05-01

129

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

130

A Few Techniques for Preparing Conductive Material Films for Sputtering-Type Electron Cyclotron Resonance Microwave Plasma  

Microsoft Academic Search

A few techniques are developed for preparing conductive material films for sputtering type electron cyclotron resonance microwave plasma. Microwave pressure window contamination, which is the most serious obstacle to conductive film preparation, can be avoided by using a vacuum microwave guide. Dense plasmas of 1011 cm-3 are obtained at a gas pressure of 10-2 Pa, and several metal films, including

Morito Matsuoka; Ken'ichi Ono

1989-01-01

131

A comparison of neural network and fuzzy clustering techniques in segmenting magnetic resonance images of the brain  

Microsoft Academic Search

Magnetic resonance (MR) brain section images are segmented and then synthetically colored to give visual representations of the original data with three approaches: the literal and approximate fuzzy c-means unsupervised clustering algorithms, and a supervised computational neural network. Initial clinical results are presented on normal volunteers and selected patients with brain tumors surrounded by edema. Supervised and unsupervised segmentation techniques

L. O. Hall; A. M. Bensaid; L. P. Clarke; R. P. Velthuizen; M. S. Silbiger; J. C. Bezdek

1992-01-01

132

Robust control of linear ceramic motor drive with LLCC resonant technique.  

PubMed

This study presents a robust control system for a linear ceramic motor (LCM) that is driven by a high-frequency voltage source inverter using two-inductance two-capacitance (LLCC) resonant technique. The structure and driving principle of the LCM are introduced. Because the dynamic characteristics and motor parameters of the LCM are nonlinear and time varying, a robust control system is designed based on the hypothetical dynamic model to achieve high-precision position control. The presentation of robust control for the LCM drive system is divided into three parts, which comprise state feedback controller, feed-forward controller, and uncertainty controller. The adaptation laws of control gains in the robust control system are derived in the sense of Lyapunov stability theorem such that the stability of the control system can be guaranteed. It not only has the learning ability similar to intelligent control, but also its control framework is more simple than intelligent control. With the proposed robust control system, the controlled LCM drive possesses the advantages of good tracking control performance and robustness to uncertainties. The effectiveness of the proposed robust control system is verified by experimental results in the presence of uncertainties. In addition, the advantages of the proposed control system are indicated in comparison with the traditional integral-proportional (IP) position control system. PMID:12894924

Wai, Rong-Jong

2003-07-01

133

An adaptive fuzzy-neural-network controller for ultrasonic motor drive using the LLCC resonant technique.  

PubMed

In this study an adaptive fuzzy-neural-network controller (AFNNC) is proposed to control a rotary traveling wave-type ultrasonic motor (USM) drive system. The USM is derived by a newly designed, high frequency, two-phase voltage source inverter using two inductances and two capacitances (LLCC) resonant technique. Then, because the dynamic characteristics of the USM are complicated and the motor parameters are time varying, an AFNNC is proposed to control the rotor position of the USM. In the proposed controller, the USM drive system is identified by a fuzzy-neural-network identifier (FNNI) to provide the sensitivity information of the drive system to an adaptive controller. The backpropagation algorithm is used to train the FNNI on line. Moreover, to guarantee the convergence of identification and tracking errors, analytical methods based on a discrete-type Lyapunov function are proposed to determine the varied learning rates of the FNNI and the optimal learning rate of the adaptive controller. In addition, the effectiveness of the adaptive fuzzy-neural-network (AFNN) controlled USM drive system is demonstrated by some experimental results. PMID:18238472

Lin, F J; Wai, R J; Lin, H H

1999-01-01

134

Determination of nucleic acids with a near infrared cyanine dye using resonance light scattering technique  

NASA Astrophysics Data System (ADS)

A new method for the determination of nucleic acids has been developed based on the enhancement effect of resonance light scattering (RLS) with a cationic near infrared (NIR) cyanine dye. Under the optimal conditions, the enhanced RLS intensity at 823 nm is proportional to the concentration of nucleic acids in the range of 0-400 ng mL -1 for both calf thymus DNA (CT DNA) and fish sperm DNA (FS DNA), 0-600 ng mL -1 for snake ovum RNA (SO RNA). The detection limits are 3.5 ng mL -1, 3.4 ng mL -1 and 2.9 ng mL -1 for CT DNA, FS DNA and SO RNA, respectively. Owing to performing in near infrared region, this method not only has high sensitivity endowed by RLS technique but also avoids possible spectral interference from background. It has been applied to the determination of nucleic acids in synthetic and real samples and satisfactory results were obtained.

Fang, Fang; Zheng, Hong; Li, Ling; Wu, Yuqin; Chen, Jinlong; Zhuo, Shujuan; Zhu, Changqing

2006-06-01

135

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

136

35Cl NQR Spectra of several 2,2-bis- p-chlorophenyl chloroethane derivatives  

NASA Astrophysics Data System (ADS)

Measurement of NQR line frequency at 77 K have been performed for the following compounds: 1-chloro-2,2-bis-(p-chlorophenyl) ethylene (DDMU), 1,1-dichloro-2,2-bis-(p-chlorophenyl) ethylene (DDE), 1,1-dichloro-2,2-bis-(p-chlorophenyl) ethane (ODD), 1,1,1-trichloro-2,2-bis (p-chlorophenyl) ethane (DDT). An attempt to assign spectrum lines to particular Cl nuclei in a molecule has been made. Molecular and crystallographic inequivalences occurring in these compounds have been considered. Comparison of the NQR and crystallographic data revealed the influence of phenyl rings conformation on electric charge distribution in the studied molecules.

Nogaj, B.; Pietrzak, J.; Wielopolska, E.; Schroeder, G.; Jarczewski, A.

137

Intrinsic Tryptophan Fluorescence in the Detection and Analysis of Proteins: A Focus on Förster Resonance Energy Transfer Techniques  

PubMed Central

Förster resonance energy transfer (FRET) occurs when the distance between a donor fluorophore and an acceptor is within 10 nm, and its application often necessitates fluorescent labeling of biological targets. However, covalent modification of biomolecules can inadvertently give rise to conformational and/or functional changes. This review describes the application of intrinsic protein fluorescence, predominantly derived from tryptophan (?EX ? 280 nm, ?EM ? 350 nm), in protein-related research and mainly focuses on label-free FRET techniques. In terms of wavelength and intensity, tryptophan fluorescence is strongly influenced by its (or the protein’s) local environment, which, in addition to fluorescence quenching, has been applied to study protein conformational changes. Intrinsic Förster resonance energy transfer (iFRET), a recently developed technique, utilizes the intrinsic fluorescence of tryptophan in conjunction with target-specific fluorescent probes as FRET donors and acceptors, respectively, for real time detection of native proteins. PMID:25490136

Ghisaidoobe, Amar B. T.; Chung, Sang J.

2014-01-01

138

Probing excited states of NO involved in multistate interactions using the optical-optical double resonance-multiphoton ionization technique  

SciTech Connect

Many new transitions from the (3ssigma) A/sup 2/..sigma../sup +/ state to higher Rydberg and valence states in /sup 14/N/sup 16/O have been observed by the technique of optical-optical double resonance-multiphoton ionization. Upper states include members from the np, nd, nf Rydberg states (n = 3 to 6) and several vibrational levels of the B/sup 2/PI and L/sup 2/PI valence states. The spectral simplification aspect of the double resonance technique allows for the observation of these spectra without appreciable band overlap. Analysis of our data leads to the identification of several previously unobserved mixed Rydberg-valence vibrational levels. Discussions of the Rydberg-valence interactions in the 68,600-71,200-cm/sup -1/ energy region of /sup 14/N/sup 16/O are presented in light of these results. 31 references, 12 figures, 15 tables.

Cheung, W.Y.; Chupka, W.A.; Colson, S.D.; Gauyacq, D.; Avouris, P.; Wynne, J.J.

1986-03-13

139

The use of magnetic resonance imaging techniques in assessing the uptake of surface treatments and water movement through stone faces  

Microsoft Academic Search

This paper addresses some practical questions regarding the influence of hydrophobic treatments on the movement of water in\\u000a sandstone. The broad line gradient echo magnetic resonance imaging technique has been used for monitoring the depth of penetration\\u000a of alkyl alkoxysilane treatment into untreated sandstone and subsequently to visualise the movement and spatial distribution\\u000a profile of water in the untreated and

T. B. Benson; P. J. McDonald; M. Mulheron; S. O. Nwaubani

1998-01-01

140

An iterative technique for refinement of selective excitations for magnetic resonance imaging  

E-print Network

Selective RF pulses are needed or many application in magnetic resonance imaging (MRI). The desired excitation profile is omen used as the spectrum of the applied RF pulse; the modulation waveform of the RF pulse which approximately excites...

Lebsack, Eliot Todd

1999-01-01

141

In-situ measurements of plasma parameters in the equatorial ionosphere by the resonance cone technique  

NASA Astrophysics Data System (ADS)

Resonance cone data obtained during a joint Indo-German rocket campaign in the equatorial ionosphere are presented. Plasma parameters are derived from the experimental data and compared with standard Langmuir probe measurements.

Thiemann, H.; Piel, A.; Gupta, S. P.

142

Photochemical processes in photosynthesis studied by advanced electron paramagnetic resonance techniques  

Microsoft Academic Search

Various continuous-wave and pulse electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) experiments performed on the radical species occurring in photosynthetic reaction centers of plants and bacteria during light-induced charge separation are reviewed here. Emphasis is placed on time-resolved experiments per- formed on short-lived intermediate states such as radical pairs and triplet states for which also hyperfine information

Wolfgang Lubitz

2003-01-01

143

Mass perturbation techniques for tuning and decoupling of a Disk Resonator Gyroscope  

NASA Astrophysics Data System (ADS)

Axisymmetric microelectromechanical (MEM) vibratory rate gyroscopes are designed so that the two Coriolis-coupled modes exploited for rate sensing possess equal modal frequencies and so that the central post which attaches the resonator to the sensor case is a nodal point of the these two modes. The former quality maximizes the signal-to-noise ratio of the sensor, while the latter quality eliminates any coupling of linear acceleration to the modes of interest, which, if present, creates spurious rate signals in response to linear vibration of the sensor case. When the gyro resonators are fabricated, however, small mass and stiffness asymmetries cause the frequencies of the two modes to deviate from each other and couple these modes to linear acceleration. In a resonator post-fabrication step, these effects can be reduced by altering the mass distribution of the resonator. In this dissertation, a scale model of the axisymmetric resonator of the Disk Resonator Gyroscope (DRG) is used to develop and test methods that successfully reduce frequency detuning (Part I) and linear acceleration coupling (Part II) through guided mass perturbations.

Schwartz, David

144

Advanced numerical technique for analysis of surface and bulk acoustic waves in resonators using periodic metal gratings  

NASA Astrophysics Data System (ADS)

A numerical technique characterized by a unified approach for the analysis of different types of acoustic waves utilized in resonators in which a periodic metal grating is used for excitation and reflection of such waves is described. The combination of the Finite Element Method analysis of the electrode domain with the Spectral Domain Analysis (SDA) applied to the adjacent upper and lower semi-infinite regions, which may be multilayered and include air as a special case of a dielectric material, enables rigorous simulation of the admittance in resonators using surface acoustic waves, Love waves, plate modes including Lamb waves, Stonely waves, and other waves propagating along the interface between two media, and waves with transient structure between the mentioned types. The matrix formalism with improved convergence incorporated into SDA provides fast and robust simulation for multilayered structures with arbitrary thickness of each layer. The described technique is illustrated by a few examples of its application to various combinations of LiNbO3, isotropic silicon dioxide and silicon with a periodic array of Cu electrodes. The wave characteristics extracted from the admittance functions change continuously with the variation of the film and plate thicknesses over wide ranges, even when the wave nature changes. The transformation of the wave nature with the variation of the layer thicknesses is illustrated by diagrams and contour plots of the displacements calculated at resonant frequencies.

Naumenko, Natalya F.

2014-09-01

145

Dual-mode temperature compensation technique for laser stabilization to a crystalline whispering gallery mode resonator.  

PubMed

Frequency stabilization of a diode laser locked to a whispering gallery mode (WGM) reference resonator made of a MgF2 single crystal is demonstrated. The strong thermal dependence of the difference frequency between two orthogonally polarized TE an TM modes (dual-mode frequency) of the optically anisotropic crystal material allows sensitive measurement of the resonator's temperature within the optical mode volume. This dual-mode signal was used as feedback for self-referenced temperature stabilization to nanokelvin precision, resulting in frequency stability of 0.3 MHz/h at 972 nm, which was measured by comparing with an independent ultrastable laser. PMID:23038559

Fescenko, I; Alnis, J; Schliesser, A; Wang, C Y; Kippenberg, T J; Hänsch, T W

2012-08-13

146

Sensitivity of Optically Enhanced Magnetic Resonance While magnetic resonance is one of the less sensitive spectroscopic techniques, there are a number  

E-print Network

Sensitivity of Optically Enhanced Magnetic Resonance While magnetic resonance is one of the less electronic or nuclear spins. Compared to conventional magnetic resonance, the sensitivity can be increased. Polarization Figure 1: Spin polarization The magnetic resonance signal is generally proportional to the degree

Suter, Dieter

147

A magnetic resonance spectroscopy technique to determine the stomach emptying rate of mixed diets in growing rats.  

PubMed

A rapid technique allowing the accurate determination of stomach emptying rate (SER) would be useful for understanding the process of digestion. The development of a rapid magnetic resonance spectroscopy (MRS) technique based on the marker AlCl(3)-6H(2)O (Al-MRS) to determine the real-time SER of foods in a rat model is described. Experiments were conducted to establish several variables for the Al-MRS technique and validate the technique against the traditional serial slaughter method. Overnight feed-deprived rats (n = 8/treatment) were gavaged with a single dose of a semisynthetic meat or soy bean protein isolate-based diet containing the marker AlCl(3)-6H(2)O in acidified water (pH 2). Rats were either placed individually in the magnetic resonance spectrometer to estimate the SER from the real-time decrease in the aluminum (Al) signal or killed and their stomach chyme collected at prescribed times postprandially to determine the SER. The concentration of diet in the gavage mixture did not influence the SER. In contrast, rat body weight (BW), gavage volume, and dietary marker concentration affected SER (P < 0.05). The optimal BW range, gavage volume, and marker concentration that gave repeatable SER values were 280-320 g, 2-4 mL, and 55 g/L, respectively. Correlations were found for SER between Al-MRS and serial slaughter methods (r = 0.81-0.95; P < 0.001). Al-MRS is a robust, rapid, and straightforward technique for predicting the SER of food. PMID:23427332

Montoya, Carlos A; Hindmarsh, Jason P; Moughan, Paul J; Rutherfurd, Shane M

2013-04-01

148

Variable-Pitch Rectangular Cross-section Radiofrequency Coils for the Nitrogen-14 Nuclear Quadrupole Resonance Investigation of Sealed Medicines Packets  

PubMed Central

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 14N 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

2012-01-01

149

Direct measurement of resonance Raman spectra and cross sections by a polarization difference technique.  

PubMed

Resonant Raman (RR) spectroscopy, despite its many promising applications in analytical chemistry and biology, remains an experimental challenge (compared to standard Raman) primarily because of the presence of large fluorescence backgrounds overwhelming the RR signals. The observation of RR spectra of fluorophores therefore requires the use of specialized, picosecond-time-resolved setups. Here, we present and demonstrate a method, based on polarization-difference, by which RR spectra and cross sections can be measured using the most standard Raman setup with continuous wave excitation and CCD-based detection. The method is applied to the dyes Nile Blue and rhodamine 6G under resonant excitation. This work should open a new era in RR spectroscopy, where RR spectra can be routinely measured and studied with conventional Raman systems. PMID:22571823

Le Ru, Eric C; Schroeter, Lina C; Etchegoin, Pablo G

2012-06-01

150

Method for high resolution magnetic resonance analysis using magic angle technique  

DOEpatents

A method of performing a magnetic resonance analysis of a biological object that includes placing the object in a main magnetic field (that has a static field direction) and in a radio frequency field; rotating the object at a frequency of less than about 100 Hz around an axis positioned at an angle of about 54.degree.44' relative to the main magnetic static field direction; pulsing the radio frequency to provide a sequence that includes a phase-corrected magic angle turning pulse segment; and collecting data generated by the pulsed radio frequency. The object may be reoriented about the magic angle axis between three predetermined positions that are related to each other by 120.degree.. The main magnetic field may be rotated mechanically or electronically. Methods for magnetic resonance imaging of the object are also described.

Wind, Robert A.; Hu, Jian Zhi

2003-12-30

151

Method for high resolution magnetic resonance analysis using magic angle technique  

DOEpatents

A method of performing a magnetic resonance analysis of a biological object that includes placing the object in a main magnetic field (that has a static field direction) and in a radio frequency field; rotating the object at a frequency of less than about 100 Hz around an axis positioned at an angle of about 54.degree.44' relative to the main magnetic static field direction; pulsing the radio frequency to provide a sequence that includes a phase-corrected magic angle turning pulse segment; and collecting data generated by the pulsed radio frequency. The object may be reoriented about the magic angle axis between three predetermined positions that are related to each other by 120.degree.. The main magnetic field may be rotated mechanically or electronically. Methods for magnetic resonance imaging of the object are also described.

Wind, Robert A.; Hu, Jian Zhi

2004-12-28

152

Mass perturbation techniques for tuning and decoupling of a Disk Resonator Gyroscope  

Microsoft Academic Search

Axisymmetric microelectromechanical (MEM) vibratory rate gyroscopes are designed so that the two Coriolis-coupled modes exploited for rate sensing possess equal modal frequencies and so that the central post which attaches the resonator to the sensor case is a nodal point of the these two modes. The former quality maximizes the signal-to-noise ratio of the sensor, while the latter quality eliminates

David Schwartz

2010-01-01

153

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

154

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

155

UV resonance Raman spectroscopy: A new technique for speciation of aromatics in complex matrices  

Microsoft Academic Search

Vibrational spectroscopic techniques such as IR and Raman are exquisitely sensitive to molecular structure. These techniques yield incisive results in studies of pure compounds or for rather simple mixtures, but are rarely used for the analysis of complex systems. Indeed, IR can be utilized for quantitative investigations in special cases for complex systems if the analyte of interest shows an

S. A. Asher; C. M. Jones

1986-01-01

156

Neutron Resonance Transmission Analysis (NRTA): A Nondestructive Assay Technique for the Next Generation Safeguards Initiative’s Plutonium Assay Challenge  

SciTech Connect

This is an end-of-year report for a project funded by the National Nuclear Security Administration's Office of Nuclear Safeguards (NA-241). The goal of this project is to investigate the feasibility of using Neutron Resonance Transmission Analysis (NRTA) to assay plutonium in commercial light-water-reactor spent fuel. This project is part of a larger research effort within the Next-Generation Safeguards Initiative (NGSI) to evaluate methods for assaying plutonium in spent fuel, the Plutonium Assay Challenge. The first-year goals for this project were modest and included: 1) developing a zero-order MCNP model for the NRTA technique, simulating data results presented in the literature, 2) completing a preliminary set of studies investigating important design and performance characteristics for the NRTA measurement technique, and 3) documentation of this work in an end of the year report (this report). Research teams at Los Alamos National Laboratory (LANL), Lawrence Berkeley National Laboratory (LBNL), Pacific Northwest National Laboratory (PNNL), and at several universities are also working to investigate plutonium assay methods for spent-fuel safeguards. While the NRTA technique is well proven in the scientific literature for assaying individual spent fuel pins, it is a newcomer to the current NGSI efforts studying Pu assay method techniques having just started in March 2010; several analytical techniques have been under investigation within this program for two to three years or more. This report summarizes a nine month period of work.

J. W. Sterbentz; D. L. Chichester

2010-12-01

157

High resolution image acquisition from magnetic resonance and computed tomography scans using the curvelet fusion algorithm with inverse interpolation techniques.  

PubMed

We present a new approach, based on the curvelet transform, for the fusion of magnetic resonance and computed tomography images. The objective of this fusion process is to obtain images, with as much detail as possible, for medical diagnosis. This approach is based on the application of the additive wavelet transform on both images and the segmentation of their detail planes into small overlapping tiles. The ridgelet transform is then applied on each of these tiles, and the fusion process is performed on the ridgelet transforms of the tiles. To maximize the benefit of the fused images, inverse interpolation techniques are used to obtain high resolution images from the low resolution fused images. Three inverse interpolation techniques are presented and compared. Simulation results show the superiority of the proposed curvelet fusion approach to the traditional discrete wavelet transform fusion technique. Results also reveal that inverse interpolation techniques have succeeded in obtaining high resolution images from the fused images with better quality than that of the traditional cubic spline interpolation technique. PMID:20062497

Ali, Fatma E; El-Dokany, Ibrahim M; Saad, Abdelfattah A; Al-Nuaimy, Waleed; Abd El-Samie, Fathi E

2010-01-01

158

Technique for magnetic susceptibility determination in the highly doped semiconductors by electron spin resonance  

SciTech Connect

A method for determining the magnetic susceptibility in the highly doped semiconductors is considered. It is suitable for the semiconductors near the metal - insulator transition when the conductivity changes very quickly with the temperature and the resonance line form distorts. A procedure that is based on double integration of the positive part of the derivative of the absorption line having a Dyson shape and takes into account the depth of the skin layer is described. Analysis is made for the example of arsenic-doped germanium samples at a rather high concentration corresponding to the insulator-metal phase transition.

Veinger, A. I.; Zabrodskii, A. G.; Tisnek, T. V.; Goloshchapov, S. I.; Semenikhin, P. V. [Ioffe Institute of the Russian Academy of Sciences, St. Petersburg (Russian Federation)

2014-08-20

159

Hyperpolarized Magnetic Resonance: A Novel Technique for the In Vivo Assessment of Cardiovascular Disease  

PubMed Central

Non-invasive imaging plays a central role in cardiovascular disease for determining diagnosis, prognosis, and optimizing patient management. Recent experimental studies have demonstrated that monitoring hyperpolarized 13C-labelled tracers with magnetic resonance imaging and spectroscopy (MRI and MRS) offers a new way to investigate the normal and diseased heart, and that the technology may be useful in patients with heart disease. In this review, we show how hyperpolarized 13C-labelled tracers are generated and have been applied experimentally, and outline the methodological advances currently underway to enable translation of hyperpolarized 13C MRI and MRS into the clinic. Using hyperpolarized 13C-labelled metabolites and metabolic MRI and MRS could help assessment of many human cardiovascular diseases, including coronary artery disease, heart failure and metabolic cardiomyopathies. We discuss the clinical areas in which the technology may, in the future, aid in the diagnosis and management of patients with cardiovascular diseases, including dynamic investigations of in vivo metabolism, coronary angiography and quantitative perfusion imaging. It is possible that, in the future, hyperpolarized magnetic resonance will play a major role in clinical cardiology. PMID:21969318

Schroeder, Marie A.; Clarke, Kieran; Neubauer, Stefan; Tyler, Damian J.

2011-01-01

160

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

161

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

162

Method for high resolution magnetic resonance analysis using magic angle technique  

DOEpatents

A method of performing a magnetic resonance analysis of a biological object that includes placing the biological object in a main magnetic field and in a radio frequency field, the main magnetic field having a static field direction; rotating the biological object at a rotational frequency of less than about 100 Hz around an axis positioned at an angle of about 54.degree.44' relative to the main magnetic static field direction; pulsing the radio frequency to provide a sequence that includes a magic angle turning pulse segment; and collecting data generated by the pulsed radio frequency. According to another embodiment, the radio frequency is pulsed to provide a sequence capable of producing a spectrum that is substantially free of spinning sideband peaks.

Wind, Robert A.; Hu, Jian Zhi

2003-11-25

163

Study on naringenin-CTMAB-DNA system by resonance light scattering technique and its analytical application  

NASA Astrophysics Data System (ADS)

A new high-sensitivity determination method of deoxyribonucleic acid (DNA) with detection limit at nanogram levels was proposed. Based on the measurement of resonance light scattering (RLS), it was found DNA could combine with naringenin and cetyltrimethylammonium bromide (CTMAB) in basic Tris-HCl buffer and produce enhanced RLS signal. The optimum conditions for this system were studied in detail. The enhanced intensity of RLS of naringenin-CTMAB at 353 nm was directly proportional to the concentration of DNA in the range of 0.017-1.7 ?g mL -1. The detection limit was 5.06 ng mL -1. Using the proposed method, the synthetic samples were analyzed with satisfactory results, the recovery was 99.3-105.0% and RSD was 0.7-3.7%.

Bi, Shuyun; Wang, Yu; Pang, Bo; Yan, Lili

2011-09-01

164

[Determination of palmatine hydrochloride based on the interaction with morin by resonance light scattering technique].  

PubMed

A novel resonance light scattering method for the determination of PaH was developed based on the interaction of Palmatine hydrochloride (PaH) with Morin in pH 4. 6 HAc-NaAc buffer medium, and this interaction can result in largely enhanced resonance light scattering (RLS) signal characterized by a peak at 308.0 nm. It was found that the enhanced RLS signals intensity (I(RLS)) at 308.0 nm is proportional to the concentration of PaH. The limit of detection is 8.0 nmol x L(-1) and the linear range is from 0.08 to 1.0 mol x L(-1). In this study, the mechanism of this reaction was investigated by scanning electron microscope (SEM), dynamic light scattering (DLS) and UV absorption spectrum. The SEM images and DLS graph show that ion-association complex aggregated after the addition of PaH. The experimental condition optimization results indicate that when the buffer medium is pH 4.6 HAc-NaAc without adding NaCl, the system has a good response for PaH. The authors investigated the stability of this system. The results indicate that this reaction system has a rapid response and the IRLS can reach the maximum within 5 min and remain stable at least for 120 min. The tolerance of coexisting foreign substances in the system was also studied. The research results show that the common metal ions, inorganic anions, a part of carbohydrate and amino acids have negligible effects on the analysis of PaH. This proposed method has some advantages including simplicity, rapidity and sensitivity. It also has been applied to the detection of PaH in tablet and capsule samples with RSD ? 3.3%. PMID:25358169

Li, Jia-yu; Li, Hua-chun; Wu, Fei

2014-06-01

165

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

166

Advanced Diffusion-Weighted Magnetic Resonance Imaging Techniques of the Human Spinal Cord  

PubMed Central

Unlike those of the brain, advances in diffusion-weighted imaging (DWI) of the human spinal cord have been challenged by the more complicated and inhomogeneous anatomy of the spine, the differences in magnetic susceptibility between adjacent air and fluid-filled structures and the surrounding soft tissues, and the inherent limitations of the initially used echo-planar imaging techniques used to image the spine. Interval advances in DWI techniques for imaging the human spinal cord, with the specific aims of improving the diagnostic quality of the images, and the simultaneous reduction in unwanted artifacts have resulted in higher-quality images that are now able to more accurately portray the complicated underlying anatomy and depict pathologic abnormality with improved sensitivity and specificity. Diffusion tensor imaging (DTI) has benefited from the advances in DWI techniques, as DWI images form the foundation for all tractography and DTI. This review provides a synopsis of the many recent advances in DWI of the human spinal cord, as well as some of the more common clinical uses for these techniques, including DTI and tractography. PMID:22158130

Andre, Jalal B.; Bammer, Roland

2012-01-01

167

Resonance ultrasonic vibrations in Cz-Si wafers as a possible diagnostic technique in ion implantation  

Microsoft Academic Search

The semiconductor industry does not have effective metrology for well implants. The ability to measure such deep level implants will become increasingly important as we progress along the technology road map. This work explores the possibility of using the acoustic whistle effect on ion implanted silicon wafers. The technique detects the elastic stress and defects in silicon wafers by measuring

Z. Y. Zhao; S. Ostapenko; R. Anundson; M. Tvinnereim; A. Belyaev; M. Anthony

2001-01-01

168

NON-INVASIVEIN VIVU TEhlPERATURE MAPPING OF ULTRASOUND HEATING USING MAGNETIC RESONANCE TECHNIQUES  

E-print Network

and 45OC has been shown to kill cancer cells. Monitoring of the temperature in both the tumor and 1051. Initial experiments demonstrate that this technique can be used to measure ultrasound induced temperature agree with the heating theory. I. INTRODUCTION The hypothesis behind this research is that tissue

Illinois at Urbana-Champaign, University of

169

In-Situ Characterization of Tissue Blood Flow, Blood Content, and Water State Using New Techniques in Magnetic Resonance Imaging.  

NASA Astrophysics Data System (ADS)

Tissue blood flow, blood content, and water state have been characterized in-situ with new nuclear magnetic resonance imaging techniques. The sensitivities of standard techniques to the physiologic tissue parameters spin density (N_{rm r}) and relaxation times (T_1 and T_2 ) are mathematically defined. A new driven inversion method is developed so that tissue T_1 and T_2 changes produce cooperative intensity changes, yielding high contrast, high signal to noise, and sensitivity to a wider range of tissue parameters. The actual tissue parameters were imaged by automated collection of multiple-echo data having multiple T _1 dependence. Data are simultaneously fit by three-parameters to a closed-form expression, producing lower inter-parameter correlation and parameter noise than in separate T_1 or T_2 methods or pre-averaged methods. Accurate parameters are obtained at different field strengths. Parametric images of pathology demonstrate high sensitivity to tissue heterogeneity, and water content is determined in many tissues. Erythrocytes were paramagnetically labeled to study blood content and relaxation mechanisms. Liver and spleen relaxation were enhanced following 10% exchange of animal blood volumes. Rapid water exchange between intracellular and extracellular compartments was validated. Erythrocytes occupied 12.5% of renal cortex volume, and blood content was uniform in the liver, spleen and kidney. The magnitude and direction of flow velocity was then imaged. To eliminate directional artifacts, a bipolar gradient technique sensitized to flow in different directions was developed. Phase angle was reconstructed instead of intensity since the former has a 2pi -fold higher dynamic range. Images of flow through curves demonstrated secondary flow with a centrifugally-biased laminar profile and stationary velocity peaks along the curvature. Portal vein flow velocities were diminished or reversed in cirrhosis. Image artifacts have been characterized and removed. The foldover in magnified images was eliminated by exciting limited regions with orthogonal pi/2 and pi pulses. Off-midline regions were imaged by tandemly offsetting the phase-encoding and excitation. Artifacts due to non-steady-state conditions were demonstrated. The approach to steady state was defined by operators and vectors, and any repeated series of RF pulses was proven to produce a steady-state. The vector difference between the magnetization and its steady state value is relatively constant during the approach. The repetition time relative to T_1 is the main determinant of approach rate, and off-resonant RF pulses incoherent with the magnetization produce a more rapid approach than on-resonant pulses.

Conturo, Thomas Edward

170

Bone micro-damage assessment using non-linear resonant ultrasound spectroscopy (NRUS) techniques: a feasibility study.  

PubMed

Non-linear resonant ultrasound spectroscopy (NRUS) is a technique exploiting the significant non-linear behavior of damaged materials, related to the presence of damage. This study shows for the first time the feasibility of this technique for damage assessment in bone. Two samples of bovine cortical bone were subjected to a progressive damage experiment. Damage accumulation was progressively induced in the samples by mechanical testing. For independent assessment of damage, X-ray CT imaging was performed at each damage step, but only helped in the detection of the prominent cracks. Synchrotron micro-CT imaging and histology using epifluorescence microscopy were performed in one of the two samples at the last damage step and allowed detection of micro-cracks for this step. As the quantity of damage accumulation increased, NRUS revealed a corresponding increase in the non-linear response. The measured change in non-linear response is much more sensitive than the change in elastic modulus. The results suggest that NRUS could be a potential tool for micro-damage assessment in bone. Further work has to be carried out for a better understanding of the physical nature of damaged bone, and for the ultimate goal of in vivo implementation of the technique where bone access will be a challenging problem. PMID:16876843

Muller, M; Tencate, J A; Darling, T W; Sutin, A; Guyer, R A; Talmant, M; Laugier, P; Johnson, P A

2006-12-22

171

Combined SLD Measurement of $A_{b}$ at the $Z^{0}$ Resonance using Various Techniques  

E-print Network

We present a new preliminary combination of measurements of the parity-violation parameter Ab made by the SLD collaboration using various experimental techniques. The techniques differ in detail, but in general a sample of bb events is selected or enhanced by using the topologically reconstructed mass of the separated vertices formed by decaying B hadrons. The direction of the b(bbar) quark is signed by one of four final state tags: jet charge, vertex charge, leptons, or identified K+- from the b vertex. We account for statistical and systematic correlations between the four analyses to arrive at our combined result: Ab=0.905 +/- 0.017 {stat} +/- 0.020 (syst).

Abe, K; Akagi, T; Akimoto, H; Allen, N J; Ash, William W; Aston, D; Baird, K G; Baltay, C; Band, H R; Barakat, M B; Bardon, O; Barklow, Timothy L; Bashindzhagian, G L; Bauer, J M; Bellodi, G; Benvenuti, Alberto C; Bilei, G M; Bisello, D; Blaylock, G; Bogart, J R; Bower, G R; Brau, J E; Breidenbach, M; Bugg, W M; Burke, D; Burnett, T H; Burrows, P N; Byrne, R M; Calcaterra, A; Calloway, D H; Camanzi, B; Carpinelli, M; Cassell, R; Castaldi, R; Castro, A; Cavalli-Sforza, M; Chou, A; Church, E; Cohn, H O; Coller, J A; Convery, M R; Cook, V; Cowan, R F; Coyne, D G; Crawford, G; Damerell, C J S; Danielson, M N; Daoudi, M; De Groot, N; Dell'Orso, R; Dervan, P J; De Sangro, R; Dima, M; Dong, D N; Doser, Michael; Dubois, R; Eisenstein, B I; Erofeeva, I; Eschenburg, V; Etzion, E; Fahey, S; Falciai, D; Fan, C; Fernández, J P; Fero, M J; Flood, K; Frey, R; Gifford, J A; Gillman, T; Gladding, G E; González, S; Goodman, E R; Hart, E L; Harton, J L; Hasuko, K; Hedges, S J; Hertzbach, S S; Hildreth, M D; Huber, J; Huffer, M E; Hughes, E W; Huynh, X; Hwang, H; Iwasaki, M; Jackson, D J; Jacques, P; Jaros, J A; Jiang, Z Y; Johnson, A S; Johnson, J R; Johnson, R A; Junk, T R; Kajikawa, R; Kalelkar, M S; Kamyshkov, Yu A; Kang, H J; Karliner, I; Kawahara, H; Kim, Y D; King, M E; King, R; Kofler, R R; Krishna, N M; Kroeger, R S; Langston, M; Lath, A; Leith, D W G S; Lia, V; Lin, C; Liu, M X; Liu, X; Loreti, M; Lu, A; Lynch, H L; Ma, J; Mahjouri, M; Mancinelli, G; Manly, S L; Mantovani, G C; Markiewicz, T W; Maruyama, T; Masuda, H; Mazzucato, E; McKemey, A K; Meadows, B T; Menegatti, G; Messner, R; Mockett, P M; Moffeit, K C; Moore, T B; Morii, M; Müller, D; Murzin, V S; Nagamine, T; Narita, S; Nauenberg, U; Neal, H A; Nussbaum, M; Oishi, N; Onoprienko, D V; Osborne, L S; Panvini, R S; Park, C H; Pavel, T J; Peruzzi, I; Piccolo, M; Piemontese, L; Pitts, K T; Plano, R J; Prepost, R; Prescott, C Y; Punkar, G D; Quigley, J; Ratcliff, B N; Reeves, T W; Reidy, J; Reinertsen, P L; Rensing, P E; Rochester, L S; Rowson, P C; Russell, J J; Saxton, O H; Schalk, T L; Schindler, R H; Schumm, B A; Schwiening, J; Sen, S; Serbo, V V; Shaevitz, M H; Shank, J T; Shapiro, G; Sherden, D J; Shmakov, K D; Simopoulos, C; Sinev, N B; Smith, S R; Smy, M B; Snyder, J A; Stängle, H; Stahl, A; Stamer, P E; Steiner, H; Steiner, R; Strauss, M G; Su, D; Suekane, F; Sugiyama, A; Suzuki, S; Swartz, M; Szumilo, A; Takahashi, T; Taylor, F E; Thom, J; Torrence, E; Toumbas, N K; Usher, T; Vannini, C; Vavra, J; Vella, E N; Venuti, J P; Verdier, R; Verdini, P G; Wagner, D L; Wagner, S R; Waite, A P; Walston, S; Watts, S J; Weidemann, A W; Weiss, E R; Whitaker, J S; White, S L; Wickens, F J; Williams, B; Williams, D C; Williams, S H; Willocq, S; Wilson, R J; Wisniewski, W J; Wittlin, J L; Woods, M; Word, G B; Wright, T R; Wyss, J; Yamamoto, R K; Yamartino, J M; Yang, X; Yashima, J; Yellin, S J; Young, C C; Yuta, H; Zapalac, G H; Zdarko, R W; Zhou, J

1999-01-01

172

Penaeus orientolis prawn freshness rapid determination method based on electronic nose and non-linear stochastic resonance technique.  

PubMed

In this paper, Penaeus orientolis prawn freshness rapid determination method using electronic nose (e-nose) and non-linear data processing technique is studied. E-nose responses to prawns stored at 4°C are measured. Meanwhile, physical/chemical indexes (firmness, pH, total volatile basic nitrogen (TVB-N), total viable count (TVC), and human sensory evaluation) are examined to provide freshness references for e-nose analysis. E-nose measurement data is analyzed by principal component analysis (PCA), stochastic resonance (SR), and double-layered cascaded serial stochastic resonance (DCSSR). PCA partially discriminates prawns under different storage time. SR and DCSSR signal-to-noise ratio (SNR) spectrum eigen values discriminate prawns successfully. Multi-variables regressions (MVR) are conducted between physical/chemical indexes and SR/DCSSR output SNR minimal (SNR-Min) values. Results indicate that SNR-Min values present more significant linearity relation with physical/chemical indexes. Prawn freshness forecasting model is developed via Harris fitting regression on DCSSR SNR-Min values. Validating experiments demonstrate that forecasting accuracy of this model is 94.29%. PMID:25551520

Wei, Liu; Yuanyuan, Han; Yanping, Cai; Jiaojiao, Jin; Guohua, Hui

2015-01-01

173

Capillary telangiectasia of the brain: imaging with various magnetic resonance techniques.  

PubMed

Brain capillary telangiectasia is an incidental vascular malformation found usually in pons and sometimes in extra- pontine sites. Typical MRI features are enhancement on post contrast T1 weighted images and signal loss on gradient echo images. We evaluated 10 patients with various MR techniques. Susceptibility weighted imaging was superior to GRE T2 in showing decreased signal due to susceptibility effects. Diffusion weighted imaging and diffusion tensor imaging proved not useful in the diagnosis. PMID:25603632

Gelal, F; Karaka?, L; Sarsilmaz, A; Yücel, K; Dündar, C; Apaydin, M

2014-01-01

174

Perfusion Magnetic Resonance Imaging: A Comprehensive Update on Principles and Techniques  

PubMed Central

Perfusion is a fundamental biological function that refers to the delivery of oxygen and nutrients to tissue by means of blood flow. Perfusion MRI is sensitive to microvasculature and has been applied in a wide variety of clinical applications, including the classification of tumors, identification of stroke regions, and characterization of other diseases. Perfusion MRI techniques are classified with or without using an exogenous contrast agent. Bolus methods, with injections of a contrast agent, provide better sensitivity with higher spatial resolution, and are therefore more widely used in clinical applications. However, arterial spin-labeling methods provide a unique opportunity to measure cerebral blood flow without requiring an exogenous contrast agent and have better accuracy for quantification. Importantly, MRI-based perfusion measurements are minimally invasive overall, and do not use any radiation and radioisotopes. In this review, we describe the principles and techniques of perfusion MRI. This review summarizes comprehensive updated knowledge on the physical principles and techniques of perfusion MRI. PMID:25246817

Li, Ka-Loh; Ostergaard, Leif; Calamante, Fernando

2014-01-01

175

Rock magnetic techniques complemented by ferromagnetic resonance spectroscopy to analyse a sediment record  

NASA Astrophysics Data System (ADS)

Environmental magnetism uses the spatial and temporal occurrence of magnetic carriers as diagnostic tools to detect environmental changes. Concentration, composition, grain size and configuration of the carriers inferred from magnetic properties are key parameters, because they are indicative of the formation conditions of magnetic phases, and/or of processes such as diagenesis and weathering. We present a detailed ferromagnetic resonance (FMR) spectroscopy analysis in concert with routinely used rock magnetic measurements to determine these parameters in a sediment record that documents the development of Lake Soppensee (Central Switzerland) since latest Pleistocene. FMR spectroscopy monitors varying concentration of the predominant magnetite/maghemite by the spectral signal intensity, whereas the stable single domain and superparamagnetic states are determined by the signal shape at room and low temperature. Fitting and simulation of FMR spectra are successfully applied to samples with well-defined magnetite components in the sediment matrix. Clear evidence for the colonization of magnetotactic bacteria (MTB) in Lake Soppensee was possible by applying empirical spectral separation to measured FMR signals that yield two magnetite populations differing in their configuration, that is, dispersed and aligned in chains. Low temperature measurements showed that these MTB can be preserved as pure or oxidized magnetite. The FMR data set confirms and completes rock magnetic information obtained from the lacustrine sedimentary record. The advanced application of FMR spectroscopy in the presented study critically highlights the benefit of this rapid and non-destructive method for future analysis of magnetic properties in environmental studies.

Kind, Jessica; Raden, Ulrike J. van; García-Rubio, Inés.; Gehring, Andreas U.

2012-10-01

176

Novel electro-optical coupling technique for magnetic resonance-compatible positron emission tomography detectors.  

PubMed

A new magnetic resonance imaging (MRI)-compatible positron emission tomography (PET) detector design is being developed that uses electro-optical coupling to bring the amplitude and arrival time information of high-speed PET detector scintillation pulses out of an MRI system. The electro-optical coupling technology consists of a magnetically insensitive photodetector output signal connected to a nonmagnetic vertical cavity surface emitting laser (VCSEL) diode that is coupled to a multimode optical fiber. This scheme essentially acts as an optical wire with no influence on the MRI system. To test the feasibility of this approach, a lutetium-yttrium oxyorthosilicate crystal coupled to a single pixel of a solid-state photomultiplier array was placed in coincidence with a lutetium oxyorthosilicate crystal coupled to a fast photomultiplier tube with both the new nonmagnetic VCSEL coupling and the standard coaxial cable signal transmission scheme. No significant change was observed in 511 keV photopeak energy resolution and coincidence time resolution. This electro-optical coupling technology enables an MRI-compatible PET block detector to have a reduced electromagnetic footprint compared with the signal transmission schemes deployed in the current MRI/PET designs. PMID:19397853

Olcott, Peter D; Peng, Hao; Levin, Craig S

2009-01-01

177

Investigation of Mn Implanted LiNbO{sub 3} applying electron paramagnetic resonance technique  

SciTech Connect

The effect of ion implantation on the LiNbO{sub 3} crystal is studied using electron paramagnetic resonance spectroscopy (EPR). EPR measurements on these crystals were performed as a function of ion species Mn and Fe and fluence at room temperature. Also the effect of the laser illumination on the EPR signal was determined by illuminating the crystal in situ and measuring the decay and growth of the EPR signal. LiNbO{sub 3}:Mn{sup 2+} at a depth of approximately 200 nm was formed by implantation of 2.5 {times} 10{sup 14} Mncm{sup 2} and 1 {times} 10{sup 17} Mn/cm{sup 2} at 2 MeV. The implanted samples were compared with bulk doped crystals. It was found that the decay and growth of Mn EPR for the implanted crystal is very small compared with the bulk doped LiNbO{sub 3}:Mn crystal. This was found to be primarily due to the spin concentration on the crystals. On the other, hand the decay time of the high fluence is about 40% slower than the decay of the low fluence implanted crystal.

Darwish, A.; Ila, D. [Alabama A and M Univ., Normal, AL (United States); Poker, D.B.; Hensley, D.K. [Oak Ridge National Lab., TN (United States). Solid State Div.

1997-10-01

178

A Wafer-Level Sn-Rich Au—Sn Bonding Technique and Its Application in Surface Plasmon Resonance Sensors  

NASA Astrophysics Data System (ADS)

Sn-rich Au—Sn solder bonding is systematically investigated. High shear strength (64MPa) and good hermeticity (a leak rate lower than 1 × 10-7 torr·l/s) are obtained for Au—Sn solder with 54 wt% Sn bonded at 310°C. The AuSn2 phase with the highest Vickers-hardness among the four stable intermetallic compounds of the Au—Sn system makes a major contribution to the high bonding strength. This bonding technique has been successfully used to package the Surface Plasmon Resonance (SPR) sensors. The Sn-rich Au—Sn solder bonding provides a reliable, low-cost, low-temperature and wafer-level hermetic packaging solution for the micro-electromechanical system devices and has potential applications in high-end biomedical sensors.

Mao, Xu; Lv, Xing-Dong; Wei, Wei-Wei; Zhang, Zhe; Yang, Jin-Ling; Qi, Zhi-Mei; Yang, Fu-Hua

2014-05-01

179

A comparison of neural network and fuzzy clustering techniques in segmenting magnetic resonance images of the brain  

NASA Technical Reports Server (NTRS)

Magnetic resonance (MR) brain section images are segmented and then synthetically colored to give visual representations of the original data with three approaches: the literal and approximate fuzzy c-means unsupervised clustering algorithms and a supervised computational neural network, a dynamic multilayered perception trained with the cascade correlation learning algorithm. Initial clinical results are presented on both normal volunteers and selected patients with brain tumors surrounded by edema. Supervised and unsupervised segmentation techniques provide broadly similar results. Unsupervised fuzzy algorithms were visually observed to show better segmentation when compared with raw image data for volunteer studies. However, for a more complex segmentation problem with tumor/edema or cerebrospinal fluid boundary, where the tissues have similar MR relaxation behavior, inconsistency in rating among experts was observed.

Hall, Lawrence O.; Bensaid, Amine M.; Clarke, Laurence P.; Velthuizen, Robert P.; Silbiger, Martin S.; Bezdek, James C.

1992-01-01

180

Structural, optical and magnetic resonance properties of TiO2 fibres grown by laser floating zone technique  

NASA Astrophysics Data System (ADS)

TiO2 fibres grown by the laser floating zone technique show the rutile crystalline phase as identified by X-ray diffraction and Raman spectroscopy. Scanning electron microscopy evidences a uniform surface, free of inclusions and without low-angle grain boundaries and bubbles. At low temperatures, the fibres luminescence is dominated by a richly structured optical centre with two well-defined zero-phonon lines at 1.579 eV and 1.574 eV followed by an intense vibronic sideband with a maximum close to 1.47 eV. Electron paramagnetic resonance revealed that substitutional chromium and iron ions are present as contaminants in the grown fibres, alongside with Ti3+ interstitials and other structural defects. The chemical nature of the defect responsible for the structured near-infrared luminescence is discussed.

Rodrigues, J.; Peres, M.; Fernandes, A. J. S.; Graça, M. P. F.; Sobolev, N. A.; Costa, F. M.; Monteiro, T.

2012-09-01

181

Quantitative Evaluation of Left Ventricular Wall Motion in Patient with Coronary Artery Bypass Grafting Using Magnetic Resonance Tagging Technique  

NASA Astrophysics Data System (ADS)

Left ventricular wall motions during systole were investigated from a mechanical perspective by using a magnetic resonance tagging technique. Subjects were 7 patients with coronary artery bypass grafting (CABG). First, by analyzing strain in the left ventricular wall, cardiac contractility was evaluated in the patients with CABG. Next, by calculating displacement in the myocardial wall, paradoxical movements following CABG were quantitatively evaluated. Strain analysis showed local decreases in circumferential strain in 4 of 7 subjects. The results of displacement analysis clarified that following CABG, the degree of radial displacement was small in the septal wall and large in the lateral wall, and circumferential displacement towards the septal wall occurred in the anterior and posterior walls. Since this behavior was seen in both reduced and normal cardiac contractility groups, paradoxical movements in the present patients were not caused by reduced cardiac contractility, but rather by rigid-body motion of the entire heart.

Inaba, Tadashi; Nakano, Takahiro; Tsutsumi, Masakazu; Kawasaki, Shingo; Kinosada, Yasutomi; Tokuda, Masataka

182

Investigating the Impact of Biological Impurities on the Liquid Vein Network in Polycrystalline Ice Using Magnetic Resonance Techniques  

NASA Astrophysics Data System (ADS)

Recent work has demonstrated that microorganisms can occupy the liquid filled inter-crystalline vein network in ice and maintain their metabolic activity under these conditions. Additionally, certain cold tolerant microorganisms produce extra-cellular proteins (i.e., ice-binding proteins) that have the ability to bind to the prism face of an ice crystal and inhibit ice recrystallization. One such microorganism is Chryseobacterium sp. V3519-10, a bacterium isolated from a depth of 3519 m in the Vostok Ice Core, Antarctica. While such an adaptation can impact ice crystal structure, it is not known what effect these proteins may have on the liquid vein network and to what extent these organisms may control their habitat. This study uses magnetic resonance techniques to investigate the effects of chemical and biological impurities on the liquid vein structure in ice. Magnetic resonance techniques are powerful tools for probing pore structure and transport dynamics in porous media systems, however, their ability to characterize ice as a porous media has not yet been fully explored. Three experimental conditions were evaluated in this study. Ices were prepared from 7 g/L NaCl solutions with; 1) addition of a quantified amount of extra-cellular proteins (>30kDa) extracted from Chryseobacterium sp. V3519-10 2) addition of equivalent concentrations of the protein, Bovine Serum Albumin (BSA) and 3) no protein addition. Samples were frozen and analyzed at -15°C. The liquid vein structure, as a function of salt and protein concentrations, was characterized to obtain information on liquid water content, vein surface to volume ratios and tortuosity as a measure of vein network interconnectivity. These measurements were non-destructive and made at various time intervals after freezing to monitor the evolution of microstructure due to recrystallization and assess the effects of the added proteins.

Brox, T. I.; Vogt, S. J.; Brown, J. R.; Skidmore, M. L.; Codd, S. L.; Seymour, J. D.

2011-12-01

183

Nuclear quadrupole resonance spectra of drawing-induced crystallization in As 2Se 3 fibers  

Microsoft Academic Search

Pulsed 75As nuclear quadrupole resonance (NQR) experiments performed on fibers of As2Se3 drawn at various rates (> 100 m\\/min) reveal structural changes from the bulk, well-annealed glass. In addition to the presence of As?As bonds in the nominally stoichiometric fibers, a distorted crystalline phase (< 10% by volume) occurs at the largest draw rates. Because they are highly distorted, these

P. Hari; P. C. Taylor; W. A. King; W. C. LaCourse

1997-01-01

184

93Nb Nuclear Quadrupole Resonance in Orthorhombic Phase of Niobium Pentabromide  

Microsoft Academic Search

The 93Nb NQR has been investigated in one phase of NbBr5 which was identified to be orthorhombic by the X-ray analysis. The resonance frequencies have been measured between 4.2 K and 423 K, its melting point. The coupling constant showed a positive temperature dependence up to melting point. The temperature dependence of the coupling constant is compared between NbBr5 and

Noriaki Okubo; Yoshihito Abe

1982-01-01

185

Pulse echo and combined resonance techniques: a full set of LGT acoustic wave constants and temperature coefficients.  

PubMed

This work reports on the determination of langatate elastic and piezoelectric constants and their associated temperature coefficients employing 2 independent methods, the pulse echo overlap (PEO) and a combined resonance technique (CRT) to measure bulk acoustic wave (BAW) phase velocities. Details on the measurement techniques are provided and discussed, including the analysis of the couplant material in the PEO technique used to couple signal to the sample, which showed to be an order of magnitude more relevant than the experimental errors involved in the data extraction. At room temperature, elastic and piezoelectric constants were extracted by the PEO and the CRT methods and showed results consistent to within a few percent for the elastic constants. Both raw acquired data and optimized constants, based on minimization routines applied to all the modes involved in the measurements, are provided and discussed. Comparison between the elastic constants and their temperature behavior with the literature reveals the recent efforts toward the consistent growth and characterization of LGT, in spite of significant variations (between 1 and 30%) among the constants extracted by different groups at room temperature. The density, dielectric permittivity constants, and respective temperature coefficients used in this work have also been independently determined based on samples from the same crystal boule. The temperature behavior of the BAW modes was extracted using the CRT technique, which has the advantage of not relying on temperature dependent acoustic couplants. Finally, the extracted temperature coefficients for the elastic and piezoelectric constants between room temperature and 120 degrees C are reported and discussed in this work. PMID:19406707

Sturtevant, Blake T; Davulis, Peter M; da Cunha, Mauricio Pereira

2009-04-01

186

35Cl Nuclear Quadrupole Resonance and Thermally Activated Molecular Motion in the 2:1 Crystalline Complex of Antimony Trichloride with Benzene  

Microsoft Academic Search

Nuclear quadrupole resonance (NQR) spectra of chlorine and antimony in the 2SbCl3 · C6H6 complex and their temperature behavior between 77 K and the melting point were studied. The spectral lines of two nonequivalent SbCl3 moieties are compared with available X-ray diffraction data. An analysis of the temperature dependence of the resonant frequency and the spin–lattice relaxation time for 35Cl

V. A. Mokeeva

2002-01-01

187

[Magnetic resonance angiography of the origin of the supraaortic trunks: the tridimensional time-of-flight with single volume technique].  

PubMed

This work was aimed at studying the origin of the epiaortic vessels with Magnetic Resonance Angiography (MRA). Twenty normal volunteers (mean age: 21.5 years) were examined with MRA with a superconductive magnet at 1 T (Impact). All volunteers were examined with a body coil and the time of flight (TOF) technique. The FISP 3D TONE sequence was used, with the following parameters: TR 46 ms, TE 10 ms, FA 20 degrees, ST 2.2 mm, matrix 192 x 256. The images, acquired on the axial plane with three presaturation pulses, were rotated according to the maximum intensity projection on the Z axis. To classify the images, a multiple choice card was used by a reader, with three diagnostic judgements for the different segments of the vessels (i.e., good, poor and not visualized). 3D TOF MRA permitted good visualization of the right and left common carotid in 80% and 77% of cases, of the right and left vertebral arteries in 55% and 50% of cases, of the left and right subclavian arteries in 47% and 62% of cases, and of the anonymous artery in 100% of cases. To conclude, our preliminary results indicate FISP 3D TOF MRA as the best noninvasive technique to study the origin of the epiaortic vessels. PMID:8830359

Carriero, A; Magarelli, N; Baratto, M; Aloia, N; Pinto, D; Scapati, C; Bonomo, L

1996-06-01

188

A noncontact resonance frequency detection technique for the assessment of the interfacial bone defect around a dental implant.  

PubMed

This study employed a noncontact resonance frequency (RF) detection technique that was developed by our group to evaluate the interfacial bone in in vitro implant-bone models. Based on our method, the implant-bone structure was excited by the acoustic energy of a loudspeaker, and its vibration response was acquired with a capacitance sensor. The spectral analysis was used to characterize the first RF value. Two types of in vitro defect models, Buccal-Lingual (BL) and Mesial-Distal (MD), were constructed for the verification. The measurements of the RF for a defect model clamped at four different heights (9, 10, 11, and 12 mm) were performed in two sensing directions (BL and MD). Moreover, each model was also analyzed using an Osstell Mentor. The obtained two parameters, RF and ISQ (Implant Stability Quotient), were statistically analyzed through one-way analysis of variance (ANOVA) and linear regression analysis for comparisons. The RF and the ISQ values obtained for all of the defect models at the four clamp heights decreased significantly (p < 0.05) with an increase in the severity of the defect. The two parameters for each imperfection increase significantly (p < 0.05) with an increase in the clamp height. Additionally, the RFs of all of the defect models are linearly correlated with their corresponding ISQs for the four clamp heights and the two measuring orientations. Therefore, our developed technique is feasible for the assessment of the postoperative healing around a dental implant. PMID:23764430

Pan, Min-Chun; Zhuang, Han-Bo; Chen, Chin-Sung; Wu, Jer-Whey; Lee, Shyh-Yuan

2013-12-01

189

Experimental Models of Brain Ischemia: A Review of Techniques, Magnetic Resonance Imaging, and Investigational Cell-Based Therapies  

PubMed Central

Stroke continues to be a significant cause of death and disability worldwide. Although major advances have been made in the past decades in prevention, treatment, and rehabilitation, enormous challenges remain in the way of translating new therapeutic approaches from bench to bedside. Thrombolysis, while routinely used for ischemic stroke, is only a viable option within a narrow time window. Recently, progress in stem cell biology has opened up avenues to therapeutic strategies aimed at supporting and replacing neural cells in infarcted areas. Realistic experimental animal models are crucial to understand the mechanisms of neuronal survival following ischemic brain injury and to develop therapeutic interventions. Current studies on experimental stroke therapies evaluate the efficiency of neuroprotective agents and cell-based approaches using primarily rodent models of permanent or transient focal cerebral ischemia. In parallel, advancements in imaging techniques permit better mapping of the spatial-temporal evolution of the lesioned cortex and its functional responses. This review provides a condensed conceptual review of the state of the art of this field, from models and magnetic resonance imaging techniques through to stem cell therapies. PMID:24600434

Canazza, Alessandra; Minati, Ludovico; Boffano, Carlo; Parati, Eugenio; Binks, Sophie

2013-01-01

190

Improvement of the sensitivity of the surface plasmon resonance sensors based on multi-layer modulation techniques  

NASA Astrophysics Data System (ADS)

In this study, a multi-layer modulation technique was used in an SPR optical fiber sensor to enhance the sensitivity of the SPR optical fiber sensor by adjusting the SPR resonant wavelength. The sputtering process deposited 20 nm of TiO2, 11 nm of SiO2 and 30 nm of gold film on the material surface to change the refractive index. Regardless of the different refractive index solutions (1.32 and 1.36), the sensitivities in wavelength interrogation of the SPR optical fiber with the single gold thin film and multi-layers modulation were 1.08×10-5 RIUs and 1.74×10-6 RIUs, respectively. The results showed the significant differences between the different refractive index solutions of 1.32 and 1.36 using the 850 nm light source to analyze the SPR optical fiber sensor in real-time. The sensitivities in intensity interrogation of the SPR optical fiber with the single gold thin film and multi-layers modulation were 1.08×10-3 RIUs and 1.73×10-4 RIUs, respectively, which indicated that the multi-layer modulation techniques could enhance the sensitivity of the SPR optical fiber sensor. The compact size of the multi-layer SPR fiber sensor had a wider detecting range of the refractive index and higher sensitivity, which had the potential for other applications in biological analysis with suitable wavelength.

Zhao, Xihong; Chu-Su, Yu; Tsai, Woo-Hu; Wang, Ching-Ho; Chuang, Tsung-Liang; Lin, Chii-Wann; Tsao, Yu-Chia; Wu, Mu-Shiang

2015-01-01

191

Advanced Magnetic Resonance Imaging techniques to probe muscle structure and function  

NASA Astrophysics Data System (ADS)

Structural and functional Magnetic Resonance Imaging (MRI) studies of skeletal muscle allow the elucidation of muscle physiology under normal and pathological conditions. Continuing on the efforts of the Muscle Imaging and Modeling laboratory, the focus of the thesis is to (i) extend and refine two challenging imaging modalities: structural imaging using Diffusion Tensor Imaging (DTI) and functional imaging based on Velocity Encoded Phase Contrast Imaging (VE-PC) and (ii) apply these methods to explore age related structure and functional differences of the gastrocnemius muscle. Diffusion Tensor Imaging allows the study of tissue microstructure as well as muscle fiber architecture. The images, based on an ultrafast single shot Echo Planar Imaging (EPI) sequence, suffer from geometric distortions and low signal to noise ratio. A processing pipeline was developed to correct for distortions and to improve image Signal to Noise Ratio (SNR). DTI acquired on a senior and young cohort of subjects were processed through the pipeline and differences in DTI derived indices and fiber architecture between the two cohorts were explored. The DTI indices indicated that at the microstructural level, fiber atrophy was accompanied with a reduction in fiber volume fraction. At the fiber architecture level, fiber length and pennation angles decreased with age that potentially contribute to the loss of muscle force with age. Velocity Encoded Phase Contrast imaging provides tissue (e.g. muscle) velocity at each voxel which allows the study of strain and Strain Rate (SR) under dynamic conditions. The focus of the thesis was to extract 2D strain rate tensor maps from the velocity images and apply the method to study age related differences. The tensor mapping can potentially provide unique information on the extracellular matrix and lateral transmission the role of these two elements has recently emerged as important determinants of force loss with age. In the cross sectional study on aging, strain rate during isometric contraction was significantly reduced in the seniors; presumably from decrease in muscle slack and increase in stiffness with age. Other parameters of interest from this study that allow inferences on the ECM and lateral transmission are the asymmetry of deformation in the fiber cross section as well as the angle between the SR and muscle fiber. The last part of thesis, which is a 'work-in-progress', is the extension to 3D SR tensor mapping using a 3D spatial, 3D velocity encoded imaging sequence. This is combined with Diffusion Tensor Imaging to obtain the lead eigenvector (muscle fiber direction) at each voxel. The 3D SR is then rotated to the basis of the DTI to obtain a 'Fiber Aligned Strain rate: FASR'. The off diagonal elements of FASR are shear strain terms. Detailed analysis of the shear strain will provide a unique non-invasive method to probe lateral transmission.

Malis, Vadim

192

An automatic method for detection and classification of Ionospheric Alfvén Resonances using signal and image processing techniques  

NASA Astrophysics Data System (ADS)

Induction coils permit us to measure the very rapid changes of the magnetic field. In June 2012, the British Geological Survey Geomagnetism team installed two high frequency (100 Hz) induction coil magnetometers at the Eskdalemuir Observatory (55.3° N, 3.2° W, L~3), in the Scottish Borders of the United Kingdom. The Eskdalemuir Observatory is one of the longest running geophysical sites in the UK (beginning operation in 1908) and is located in a rural valley with a quiet magnetic environment. The coils record magnetic field changes over an effective frequency range of about 0.1-40Hz, and encompass phenomena such as the Schumann resonances, magnetospheric pulsations and Ionospheric Alfvén Resonances (IAR). In this study we focus on the IAR, which are related to the vibration of magnetic field lines passing through the ionosphere, believed to be mainly excited by lower atmospheric electrical discharges. The IAR typically manifest as a series of spectral resonances structures (SRS) within the 1-6Hz frequency range, usually appearing a fine bands or fringes in spectrogram plots. The SRS tend to occur daily between 18.00-06.00UT at the Eskdalemuir site, disappearing during the daylight hours. They usually start as a single low frequency before bifurcating into 5-10 separate fringes, increasing in frequency until around midnight. The fringes also widen in frequency before fading around 06.00UT. Occasionally, the fringes decrease in frequency slightly around 03.00UT before fading. In order to quantify the daily, seasonal and annual changes of the SRS, we developed a new method to identify the fringes and to quantify their occurrence in frequency (f) and the change in frequency (?f). The method uses short time-series of 100 seconds to produce an FFT spectral plot from which the non-stationary peaks are identified using the residuals from a best-fit six order spline. This is repeated for an entire day of data. The peaks from each time-slice are placed into a matrix which is then treated as an image. In combination with the spectrogram image of that day, the SRS are identified using image processing techniques. The peaks can now be mapped as continuous lines throughout the spectrogram. Finally, we can investigate the f and ?f statistics over the entire length of the dataset. We intend to run the coils as a long term experiment. The data and code are available on request.

Beggan, Ciaran

2014-05-01

193

Gas-phase ion chemistry of fluoromethanes by ion cyclotron resonance spectroscopy. New techniques for the determination of carbonium ion stabilities. [Substituent effects  

Microsoft Academic Search

The gas-phase ion chemistry of the fluoromethanes CH\\/sub 4-n\\/F\\/sub n\\/(n = 1-4) has been investigated using the techniques of ion cyclotron resonance spectroscopy. The kinetics of reactions involving parent and fragment ions have been determined over a range of pressure and electron energies using trapped ion techniques complemented by the more usual method of examining the variation of ion abundance

R. J. Blint; T. B. McMahon; J. L. Beauchamp

1974-01-01

194

Structural and Functional Investigation of Flavin Binding Center of the NqrC Subunit of Sodium-Translocating NADH:Quinone Oxidoreductase from Vibrio harveyi.  

PubMed

Na+-translocating NADH:quinone oxidoreductase (NQR) is a redox-driven sodium pump operating in the respiratory chain of various bacteria, including pathogenic species. The enzyme has a unique set of redox active prosthetic groups, which includes two covalently bound flavin mononucleotide (FMN) residues attached to threonine residues in subunits NqrB and NqrC. The reason of FMN covalent bonding in the subunits has not been established yet. In the current work, binding of free FMN to the apo-form of NqrC from Vibrio harveyi was studied showing very low affinity of NqrC to FMN in the absence of its covalent bonding. To study structural aspects of flavin binding in NqrC, its holo-form was crystallized and its 3D structure was solved at 1.56 Å resolution. It was found that the isoalloxazine moiety of the FMN residue is buried in a hydrophobic cavity and that its pyrimidine ring is squeezed between hydrophobic amino acid residues while its benzene ring is extended from the protein surroundings. This structure of the flavin-binding pocket appears to provide flexibility of the benzene ring, which can help the FMN residue to take the bended conformation and thus to stabilize the one-electron reduced form of the prosthetic group. These properties may also lead to relatively weak noncovalent binding of the flavin. This fact along with periplasmic location of the FMN-binding domains in the vast majority of NqrC-like proteins may explain the necessity of the covalent bonding of this prosthetic group to prevent its loss to the external medium. PMID:25734798

Borshchevskiy, Valentin; Round, Ekaterina; Bertsova, Yulia; Polovinkin, Vitaly; Gushchin, Ivan; Ishchenko, Andrii; Kovalev, Kirill; Mishin, Alexey; Kachalova, Galina; Popov, Alexander; Bogachev, Alexander; Gordeliy, Valentin

2015-01-01

195

Structural and Functional Investigation of Flavin Binding Center of the NqrC Subunit of Sodium-Translocating NADH:Quinone Oxidoreductase from Vibrio harveyi  

PubMed Central

Na+-translocating NADH:quinone oxidoreductase (NQR) is a redox-driven sodium pump operating in the respiratory chain of various bacteria, including pathogenic species. The enzyme has a unique set of redox active prosthetic groups, which includes two covalently bound flavin mononucleotide (FMN) residues attached to threonine residues in subunits NqrB and NqrC. The reason of FMN covalent bonding in the subunits has not been established yet. In the current work, binding of free FMN to the apo-form of NqrC from Vibrio harveyi was studied showing very low affinity of NqrC to FMN in the absence of its covalent bonding. To study structural aspects of flavin binding in NqrC, its holo-form was crystallized and its 3D structure was solved at 1.56 Å resolution. It was found that the isoalloxazine moiety of the FMN residue is buried in a hydrophobic cavity and that its pyrimidine ring is squeezed between hydrophobic amino acid residues while its benzene ring is extended from the protein surroundings. This structure of the flavin-binding pocket appears to provide flexibility of the benzene ring, which can help the FMN residue to take the bended conformation and thus to stabilize the one-electron reduced form of the prosthetic group. These properties may also lead to relatively weak noncovalent binding of the flavin. This fact along with periplasmic location of the FMN-binding domains in the vast majority of NqrC-like proteins may explain the necessity of the covalent bonding of this prosthetic group to prevent its loss to the external medium. PMID:25734798

Bertsova, Yulia; Polovinkin, Vitaly; Gushchin, Ivan; Ishchenko, Andrii; Kovalev, Kirill; Mishin, Alexey; Kachalova, Galina; Popov, Alexander; Bogachev, Alexander; Gordeliy, Valentin

2015-01-01

196

A BEM technique for free-molecule flows in high frequency MEMS resonators Department of Structural Engineering, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milano, Italy  

E-print Network

A BEM technique for free-molecule flows in high frequency MEMS resonators A. Frangi Department Keywords: MEMS Free-molecule flow Dissipation a b s t r a c t A boundary element approach is proposed for the analysis of free-molecule flows in order to evaluate mechanical dissipation in micro-systems working at low

Frangi, Attilio

197

Metabolomic analysis of Strychnos nux-vomica, Strychnos icaja and Strychnos ignatii extracts by 1H nuclear magnetic resonance spectrometry and multivariate analysis techniques  

Microsoft Academic Search

1H Nuclear magnetic resonance spectrometry and multivariate analysis techniques were applied for the metabolic profiling of three Strychnos species: Strychnos nux-vomica (seeds, stem bark, root bark), Strychnos ignatii (seeds), and Strychnos icaja (leaves, stem bark, root bark, collar bark). The principal component analysis (PCA) of the 1H NMR spectra showed a clear discrimination between all samples, using the three first

Michel Frédérich; Young Hae Choi; Luc Angenot; Goetz Harnischfeger; Alfons W. M. Lefeber; Robert Verpoorte

2004-01-01

198

Dynamics of paramagnetic agents by off-resonance rotating frame technique in the presence of magnetization transfer effect  

PubMed Central

The simple method for measuring the rotational correlation time of paramagnetic ion chelates via off-resonance rotating frame technique is challenged in vivo by the magnetization transfer effect. A theoretical model for the spin relaxation of water protons in the presence of paramagnetic ion chelates and magnetization transfer effect is described. This model considers the competitive relaxations of water protons by the paramagnetic relaxation pathway and the magnetization transfer pathway. The influence of magnetization transfer to the total residual z-magnetization has been quantitatively evaluated in the context of magnetization map and various difference magnetization profiles for macromolecule conjugated Gd-DTPA in cross-linked protein gels. The numerical simulations and experimental validations confirm that the rotational correlation time for paramagnetic ion chelates can be measured even in the presence of strong magnetization transfer. This spin relaxation model also provides novel approaches to enhance the detection sensitivity for paramagnetic labeling by suppressing spin relaxations caused by magnetization transfer. The inclusion of the magnetization transfer effect allows us to use the magnetization map as a simulation tool to design efficient paramagnetic labeling targeting at specific tissues, to design experiments running at low RF power depositions, and to optimize the sensitivity for detecting paramagnetic labeling. Thus, the presented method will be a very useful tool for in vivo applications such as molecular imaging via paramagnetic labeling. PMID:17123851

Zhang, Huiming; Xie, Yang

2007-01-01

199

Magneto-optical properties of BiFeO3 thin films using surface plasmon resonance technique  

NASA Astrophysics Data System (ADS)

Indigeneously assembled surface plasmon resonance (SPR) set up has been exploited to study the magnetic field dependent optical properties of BiFeO3 thin films. BiFeO3 thin films have been deposited onto gold (Au) coated glass prism by using pulsed laser deposition technique. The surface plasmon modes in prism/Au/BiFeO3/air structure have been excited in Kretschmann configuration at the interface of Au/BiFeO3 thin films. The SPR reflectance curves obtained for prism/Au/BiFeO3/air structure were utilized to investigate the optical properties of BiFeO3 thin films at optical frequency (?=633 nm) as a function of applied magnetic field. SPR curves shows a continuous shift towards lower angles with increasing applied magnetic field, which indicate the promising application of ferromagnetic BiFeO3 film as a magnetic field sensor. Complex dielectric constant of deposited BiFeO3 film was determined by fitting the experimental SPR data with Fresnel's equations. The variation of complex dielectric constant and refractive index of BiFeO3 film was studied with increase in magnetic field, and the sensitivity of magnetic field sensor was found to be about 0.52 RIU/T.

Paliwal, Ayushi; Sharma, Anjali; Tomar, Monika; Gupta, Vinay

2014-09-01

200

Established and emerging cardiovascular magnetic resonance techniques for the assessment of stable coronary heart disease and acute coronary syndromes  

PubMed Central

Coronary heart disease (CHD) is a leading cause of death and disability worldwide. International guidelines recommend cardiovascular magnetic resonance (CMR) as an investigative option in those presenting with chest pain to inform diagnosis, risk stratify and determine the need for revascularization. CMR offers a unique method to assess global and regional cardiac function, myocardial perfusion, myocardial viability, tissue characterisation and proximal coronary anatomy all within a single study. This results in high diagnostic accuracy for the detection of significant coronary stenoses and an established role in the management of both stable CHD and acute coronary syndromes (ACS). The growing evidence base for the prognostic value of CMR, emerging advances in acquisition techniques, improvements in hardware and the completion of current major multi-centre clinical CMR trials will further raise its prominence in international guidelines and routine cardiological practice. This article will focus on the rapidly evolving role of the multi-parametric CMR examination in the assessment of patients with stable and unstable CHD. PMID:25392820

Ripley, David P.; Motwani, Manish; Plein, Sven

2014-01-01

201

Excited State Spectroscopy and Excited State Dynamics of Rh(III) and Pd(II) Chelates as Studied by Optically Detected Magnetic Resonance Techniques  

Microsoft Academic Search

In this paper we review optically detected magnetic resonance (ODMR) investigations of a series of Rh3+ (4d6) and Pd2+ (4d8) complexes in the lowest excited electron spin triplet state. Starting with a brief survey of the technique of optical detection\\u000a of magnetic resonance, zero-field and low-magnetic field ODMR results are reviewed for the tris-diimine chelates [Rh(phen)n(bpy)3?n]3+, where phen=1,10-phenanthroline, bpy=2,2?-bipyridine, and

Max Glasbeek

2001-01-01

202

Nuclear quadrupole resonance and x-ray investigation of the structure of Na2\\/3CoO2  

Microsoft Academic Search

We have synthesized various samples of the x=2\\/3 phase of sodium cobaltate NaxCoO2 and performed x-ray powder diffractions spectra to compare the diffraction with the structure proposed previously from NMR and nuclear quadrupole resonance (NQR) experiments [H. Alloul, I. R. Mukhamedshin, T. A. Platova, and A. V. Dooglav, EPL 85, 47006 (2009)]. Rietveld analyses of the data are found in

T. A. Platova; I. R. Mukhamedshin; H. Alloul; A. V. Dooglav; G. Collin

2009-01-01

203

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

204

Noise-resilient multi-frequency surface sensor for nuclear quadrupole resonance  

NASA Astrophysics Data System (ADS)

A planar nuclear quadrupole resonance (NQR) sensor has been developed. The sensor is resilient to environmental noise and is capable of simultaneous independent multi-frequency operation. The device was constructed as an open multimodal birdcage structure, in which the higher modes, generally not used in magnetic resonance, are utilized for NQR detection. These modes have smooth distributions of the amplitudes of the corresponding radiofrequency magnetic fields everywhere along the sensor's surface. The phases of the fields, on the other hand, are cyclically shifted across the sensor's surface. Noise signals coming from distant sources, therefore, induce equal-magnitude cyclically phase-shifted currents in different parts of the sensor. When such cyclically phase-shifted currents arrive at the mode connection point, they destructively interfere with each other and are cancelled out. NQR signals of polycrystalline or disordered substances, however, are efficiently detected by these modes because they are insensitive to the phases of the excitation/detection. No blind spots exist along the sensor's surface. The sensor can be used for simultaneous detection of one or more substances in locations with environmental noise.

Peshkovsky, A. S.; Cattena, C. J.; Cerioni, L. M.; Osán, T. M.; Forguez, J. G.; Peresson, W. J.; Pusiol, D. J.

2008-10-01

205

Nuclear-quadrupole double-resonance study of RbH2PO4 in the supercooled high-temperature monoclinic phase  

NASA Astrophysics Data System (ADS)

Rubidium nuclear-quadrupole-resonance (NQR) spectra have been measured in the high-temperature monoclinic phase of RbH2PO4 above Tp=86 °C and also in the supercooled high-temperature phase below Tp. At the transition into the high-temperature phase, the rubidium quadrupole-coupling constants drop by a factor of 5. The high-temperature phase is metastable below Tp. The kinetics of the transformation of the metastable phase into the stable tetragonal phase in a polycrystalline sample is determined at room temperature from the time dependence of the rubidium NQR spectra. A comparison of the present rubidium NQR data in the high-temperature monoclinic RbH2PO4 with the rubidium NQR data in monoclinic RbD2PO4 suggests that at low temperatures, supercooled monoclinic RbH2PO4 may be isostructural with the phase III of monoclinic RbD2PO4 whereas above Tp RbH2PO4 may be isostructural with phase II of RbD2PO4.

Seliger, J.; Žagar, V.; Blinc, R.

1993-06-01

206

Evaluation of agglutination strength by a flow-induced cell movement assay based surface plasmon resonance (SPR) technique.  

PubMed

A flow-induced cell movement assay combined with a surface plasmon resonance (SPR) technique was developed to quantify the agglutination strength, derived from the standard tube-agglutination test. Red blood cells (RBCs), based on the ABO blood group system, were specifically captured by anti-A and/or anti-B antibodies immobilized on a sensor surface. The agglutination strength corresponds to the amount of antigen-antibody interactions or the strength of RBC adhesion. Under a shear flow, the adherent RBCs were forced to move out of the region of interest with different average cell velocities (vc) depending upon the adhesion strength and wall shear stress (WSS). That is, a higher adhesion strength (higher agglutination strength) or lower WSS represents a lower vc or vice versa. In this work, the agglutination strength was derived from the vc that was calculated from the time derivative of the relative SPR signal by using a simple model of cell movement response, whose validity was verified. The vc values of different samples were correlated with their agglutination strengths at a given WSS and antibody surface density. The vc decreased as the agglutination strength increased, which can be considered as a linear regression. The coefficient of variation of the calculated vc decreased to 0.1 as vc increased to 30 ?m min(-1). The sensitivity of this assay can be controlled by optimizing the antibody surface density or the WSS. This assay has the capability to resolve the antigen density of A1 and B RBCs from that of A1B RBCs. PMID:25474709

Sudprasert, Krisda; Peungthum, Patjaree; Vongsakulyanon, Apirom; Amarit, Ratthasart; Somboonkaew, Armote; Sutapun, Boonsong; Kitpoka, Pimpun; Kunakorn, Mongkol; Srikhirin, Toemsak

2015-02-01

207

Invited Article: Dielectric material characterization techniques and designs of high-Q resonators for applications from micro to millimeter-waves frequencies applicable at room and cryogenic temperatures  

NASA Astrophysics Data System (ADS)

Dielectric resonators are key elements in many applications in micro to millimeter wave circuits, including ultra-narrow band filters and frequency-determining components for precision frequency synthesis. Distributed-layered and bulk low-loss crystalline and polycrystalline dielectric structures have become very important for building these devices. Proper design requires careful electromagnetic characterization of low-loss material properties. This includes exact simulation with precision numerical software and precise measurements of resonant modes. For example, we have developed the Whispering Gallery mode technique for microwave applications, which has now become the standard for characterizing low-loss structures. This paper will give some of the most common characterization techniques used in the micro to millimeter wave regime at room and cryogenic temperatures for designing high-Q dielectric loaded cavities.

Le Floch, Jean-Michel; Fan, Y.; Humbert, Georges; Shan, Qingxiao; Férachou, Denis; Bara-Maillet, Romain; Aubourg, Michel; Hartnett, John G.; Madrangeas, Valerie; Cros, Dominique; Blondy, Jean-Marc; Krupka, Jerzy; Tobar, Michael E.

2014-03-01

208

Invited article: Dielectric material characterization techniques and designs of high-Q resonators for applications from micro to millimeter-waves frequencies applicable at room and cryogenic temperatures.  

PubMed

Dielectric resonators are key elements in many applications in micro to millimeter wave circuits, including ultra-narrow band filters and frequency-determining components for precision frequency synthesis. Distributed-layered and bulk low-loss crystalline and polycrystalline dielectric structures have become very important for building these devices. Proper design requires careful electromagnetic characterization of low-loss material properties. This includes exact simulation with precision numerical software and precise measurements of resonant modes. For example, we have developed the Whispering Gallery mode technique for microwave applications, which has now become the standard for characterizing low-loss structures. This paper will give some of the most common characterization techniques used in the micro to millimeter wave regime at room and cryogenic temperatures for designing high-Q dielectric loaded cavities. PMID:24689557

Le Floch, Jean-Michel; Fan, Y; Humbert, Georges; Shan, Qingxiao; Férachou, Denis; Bara-Maillet, Romain; Aubourg, Michel; Hartnett, John G; Madrangeas, Valerie; Cros, Dominique; Blondy, Jean-Marc; Krupka, Jerzy; Tobar, Michael E

2014-03-01

209

Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers: A novel technique for ultratrace gas analysis and high-resolution spectroscopy  

Microsoft Academic Search

Cavity-enhanced resonant photoacoustic spectroscopy with optical feedback cw diode lasers (OF-CERPAS) is introduced as a novel technique for ultratrace gas analysis and high-resolution spectroscopy. In the scheme, a single-mode cw diode laser (3 mW, 635 nm) is coupled into a high-finesse linear cavity and stabilized to the cavity by optical feedback. Inside the cavity, a build-up of laser power to

Michael Hippler; Christian Mohr; Katherine A. Keen; Edward D. McNaghten

2010-01-01

210

Electron paramagnetic resonance measurements of free radicals in the intact beating heart: a technique for detection and characterization of free radicals in whole biological tissues.  

PubMed Central

Free radicals have been hypothesized to be important mediators of disease in a variety of organs and tissues. Electron paramagnetic resonance (EPR) spectroscopy can be applied to directly measure free radicals; however, it has not been possible to measure important biological radicals in situ because conventional spectrometer designs are not suitable for the performance of measurements on whole organs or tissues. We report the development of an EPR spectrometer designed for optimum performance in measuring free radicals in intact biological organs or tissues. This spectrometer consists of a 1- to 2-GHz microwave bridge with the source locked to the resonant frequency of a recessed gap loop-gap resonator. With this spectrometer, radical concentrations as low as 0.4 microM can be measured. Isolated beating hearts were studied in which simultaneous real time measurements of free radicals and cardiac contractile function were performed. This in vivo EPR technique was applied to study the kinetics of free radical uptake and metabolism in normally perfused and globally ischemic hearts. In addition, we show that this technique can be used to noninvasively measure tissue oxygen consumption. Thus, it is demonstrated that EPR spectroscopy can be applied to directly measure in vivo free radical metabolism and tissue oxygen consumption. This technique offers great promise in the study of in vivo free radical generation and the effects of this radical generation on whole biological tissues. PMID:2840672

Zweier, J L; Kuppusamy, P

1988-01-01

211

Quantitative linear and nonlinear resonance inspection techniques and analysis for material characterization: application to concrete thermal damage.  

PubMed

Developed in the late 1980s, Nonlinear Resonant Ultrasound Spectroscopy (NRUS) has been widely employed in the field of material characterization. Most of the studies assume the measured amplitude to be proportional to the strain amplitude which drives nonlinear phenomena. In 1D resonant bar experiments, the configuration for which NRUS was initially developed, this assumption holds. However, it is not true for samples of general shape which exhibit several resonance mode shapes. This paper proposes a methodology based on linear resonant ultrasound spectroscopy, numerical simulations and nonlinear resonant ultrasound spectroscopy to provide quantitative values of nonlinear elastic moduli taking into account the 3D nature of the samples. In the context of license renewal in the field of nuclear energy, this study aims at providing some quantitative information related to the degree of micro-cracking of concrete and cement based materials in the presence of thermal damage. The resonance based method is validated as regard with concrete microstructure evolution during thermal exposure. PMID:25096088

Payan, C; Ulrich, T J; Le Bas, P Y; Saleh, T; Guimaraes, M

2014-08-01

212

Interstitial laser phototherapy assisted by magnetic resonance imaging: A new technique for monitoring laser-tissue interaction  

SciTech Connect

The rapid technological advances of magnetic resonance imaging, laser fiberoptics, and compatible probes may allow treatment of deep and sometimes surgically unreachable tumors of the head and neck with minimal morbidity through interstitial laser phototherapy. In this study, a new application of magnetic resonance imaging was developed to monitor and quantify laser-induced tissue damages. Pig skin was exposed to increased levels of argon laser (514.5 nm) at energy densities between 62.5 and 375 J/cm2 as determined by an accurate and reproducible method of dosimetry. Thermal profiles were recorded using an infrared sensor and T1- and T2-weighted magnetic resonance images were taken; afterward, biopsies were performed to quantitate the level of tissue damage. Our results demonstrate that above a certain threshold of laser energy, the magnetic resonance imaging findings are temperature dependent. Appropriate development of a scale matching laser energies, temperature profiles, T1- and T2-weighted magnetic resonance images, and histological quantitation of tissue destruction will allow us to optimize the three-dimensional control and monitoring of laser-tissue interactions.

Castro, D.J.; Saxton, R.E.; Layfield, L.J.; Fetterman, H.R.; Castro, D.J.; Tartell, P.B.; Robinson, J.D.; To, S.Y.; Nishimura, E.; Lufkin, R.B. (Univ. of California, Los Angeles (USA))

1990-05-01

213

Zeeman Effect of the Nuclear Quadrupole Resonance of 81Br in para-Bromophenol and 35Cl in paraChlorophenol  

Microsoft Academic Search

The Zeeman effect of the 81Br and 35Cl nuclear quadrupole resonance has been studied with high precision on single crystals of para-bromophenol and para-chlorophenol, respectively. The results substantially agree with previous x-ray and NQR studies of para-chlorophenol (x-ray studies are known only for this substance). In p-bromophenol, four physically inequivalent sites were found, instead of two, as reported by other

P. Bucci; P. Cecchi; A. Colligiani

1969-01-01

214

Note: Matching index technique for avoiding higher order mode resonance in accelerators: INDUS-2 accelerator as a case study  

NASA Astrophysics Data System (ADS)

Resonance between circulating beam frequencies and RF cavity Higher Order Modes (HOMs) of accelerators can lead to coupled-bunch instabilities. Shifting these HOMs to avoid the resonance is a topic of active interest. A study has been carried out for the accelerating cavities of the INDUS-2. For quantitative measure of deciding which modes have to be moved and by how much, we introduce a new index called the matching index (IM), as a measure of how close a HOM is to the nearest beam mode. Depending on the value of IM, the operating scenarios are classified as safe and unsafe.

Jain, V.; Bhandarkar, U. V.; Joshi, S. C.; Krishnagopal, S.

2013-08-01

215

Note: Matching index technique for avoiding higher order mode resonance in accelerators: INDUS-2 accelerator as a case study  

SciTech Connect

Resonance between circulating beam frequencies and RF cavity Higher Order Modes (HOMs) of accelerators can lead to coupled-bunch instabilities. Shifting these HOMs to avoid the resonance is a topic of active interest. A study has been carried out for the accelerating cavities of the INDUS-2. For quantitative measure of deciding which modes have to be moved and by how much, we introduce a new index called the matching index (I{sub M}), as a measure of how close a HOM is to the nearest beam mode. Depending on the value of I{sub M}, the operating scenarios are classified as safe and unsafe.

Jain, V.; Joshi, S. C. [Raja Ramanna Centre for Advanced Technology, RRCAT, Indore 452013 (India)] [Raja Ramanna Centre for Advanced Technology, RRCAT, Indore 452013 (India); Bhandarkar, U. V. [Department of Mechanical Engineering, Indian Institute of Technology Bombay, Powai 400076, Mumbai (India)] [Department of Mechanical Engineering, Indian Institute of Technology Bombay, Powai 400076, Mumbai (India); Krishnagopal, S. [Bhabha Atomic Research Centre, Mumbai 400085 (India) [Bhabha Atomic Research Centre, Mumbai 400085 (India); Centre for Excellence in Basic Sciences, Mumbai 400098 (India)

2013-08-15

216

Improved L-C resonant decay technique for Q measurement of quasilinear power inductors: New results for MPP and ferrite powdered cores  

NASA Technical Reports Server (NTRS)

The L-C resonant decay technique for measuring circuit Q or losses is improved by eliminating the switch from the inductor-capacitor loop. A MOSFET switch is used instead to momentarily connect the resonant circuit to an existing voltage source, which itself is gated off during the decay transient. Very reproducible, low duty cycle data could be taken this way over a dynamic voltage range of at least 10:1. Circuit Q is computed from a polynomial fit to the sequence of the decaying voltage maxima. This method was applied to measure the losses at 60 kHz in inductors having loose powder cores of moly permalloy and an Mn-Zn power ferrite. After the copper and capacitor losses are separated out, the resulting specific core loss is shown to be roughly as expected for the MPP powder, but anomalously high for the ferrite powder. Possible causes are mentioned.

Niedra, Janis M.; Gerber, Scott S.

1995-01-01

217

Quantitative linear and nonlinear Resonance Inspection Techniques and Analysis for material characterization: Application to concrete thermal damage.  

E-print Network

characterization: Application to concrete thermal damage. C. Payan1 , T.J. Ulrich2 , P.Y. Le Bas2 , T. Saleh3 , M-cracking of concrete and cement based materials in the presence of thermal damage. The resonance based method is validated as regard with concrete microstructure evolution during thermal exposure. © 2013 Acoustical

Paris-Sud XI, Université de

218

Electronic resonance enhanced coherent anti-Stokes Raman scattering technique for detection of combustion species and biological molecules  

E-print Network

The application of electronic-resonance enhanced (ERE) coherent anti-Stokes Raman scattering (CARS) for the detection of nitric oxide (NO) and acetylene (C2H2) is experimentally demonstrated and the effects of various parameters on the ERE CARS...

Hanna, Sherif Fayez

2006-10-30

219

Using nitrogen-14 nuclear quadrupole resonance and electric field gradient information for the study of radiation effects  

SciTech Connect

Nitrogen-14 nuclear quadrupole resonance (NQR) was used in an attempt to detect the effects of ionizing radiation on organic material. Previously reported resonances for urea were detected at 2,913.32 {+-} 0.01 kHz and 2,347.88 {+-} 0.08 kHz with associated T{sub 2}* values 780 {+-} 20 {micro}s and 523 {+-} 24 {micro}s, respectively. The previously unreported {nu}{sub {minus}} line for urea-d{sup 4} was detected at 2,381 {+-} 0.04 Khz and used to determine accurately for the first time the values for the nuclear quadrupole coupling constant {chi} (3,548.74 {+-} 0.03 kHz) and the asymmetry parameter {eta} (0.31571 {+-} 0.00007) for urea-d{sup 4}. The inverse linewidth parameter T{sub 2}* for {nu}{sub +} was measured at 928 {+-} 23 {micro}s and for {nu}{sub {minus}} at 721 {+-} 12 {micro}s. Townes and Dailey analysis was performed and urea-d{sup 4} exhibits a 0.004 increase in lone pair electronic density and a slight decrease in N-H bond electronic density, as compared to urea, probably due to the mass difference. A relationship is proposed, referred to as NQR linewidth analysis, between the dynamic spin relaxation times T{sub 2} and T{sub 2}* and the widths of the distributions of the NQR parameters. Linewidth analysis is presented as a tool for possible use in future NQR work in all area, not just radiation effects. This relationship is tested using sodium nitrite T{sub 2} and T{sub 2}* values for {nu}{sub {minus}} and {nu}{sub {minus}} as a function of temperature.

Iselin, L.H.

1995-12-01

220

Superconducting state of filled-skutterudite RPt4Ge12 (R = La, Pr): 73Ge-NQR studies  

NASA Astrophysics Data System (ADS)

We report 73Ge-NQR studies on filled-skutterudite superconductors LaPt4Ge12 and PrPt4Ge12 under zero external field. In PrPt4Ge12, the measurement of the nuclear spin-lattice relaxation rate 1/T1 has revealed a distinct coherence peak just below Tc followed by an exponential decrease well below Tc, evidencing that PrPt4Ge12 is an s-wave superconductor with the isotropic gap in a weak-coupling regime. In LaPt4Ge12, the 1/T1 exhibits the exponential decrease well below Tc, suggesting the isotropic s-wave superconductivity. Even though 73Ge-NQR-1/T1 in LaPt4Ge12 has been measured under zero field, its coherence peak was absent, which contrasts with the result in Pr-compound. This may point to a possible anisotropy in the Fermi surface and/or some damping effect of quasiparticles in association with electron-phonon interactions.

Kanetake, F.; Mukuda, H.; Kitaoka, Y.; Sugawara, H.; Magishi, K.; Itoh, K. M.; Haller, E. E.

2010-12-01

221

Study of hydrogen in coals, polymers, oxides, and muscle water by nuclear magnetic resonance; extension of solid-state high-resolution techniques. [Hydrogen molybdenum bronze  

SciTech Connect

Nuclear magnetic resonance (NMR) spectroscopy has been an important analytical and physical research tool for several decades. One area of NMR which has undergone considerable development in recent years is high resolution NMR of solids. In particular, high resolution solid state /sup 13/C NMR spectra exhibiting features similar to those observed in liquids are currently achievable using sophisticated pulse techniques. The work described in this thesis develops analogous methods for high resolution /sup 1/H NMR of rigid solids. Applications include characterization of hydrogen aromaticities in fossil fuels, and studies of hydrogen in oxides and bound water in muscle.

Ryan, L.M.

1981-10-01

222

Ferromagnetic critical behavior in U(Co1-xFex)Al (0 ?x ?0.02 ) studied by 59Co nuclear quadrupole resonance measurements  

NASA Astrophysics Data System (ADS)

In order to investigate physical properties around a ferromagnetic (FM) quantum transition point and a tricritical point (TCP) in the itinerant-electron metamagnetic compound UCoAl, we have performed the 59Co nuclear quadrupole resonance (NQR) measurement for the Fe-substituted U(Co1-xFex)Al(x =0 ,0.5 ,1 ,and2 %) in zero external magnetic field. The Fe concentration dependence of 59Co -NQR spectra at low temperatures indicates that the first-order FM transition occurs at least above x =1 % . The magnetic fluctuations along the c axis detected by the nuclear spin-spin relaxation rate 1 /T2 exhibit an anomaly at Tmax˜20 K and enhance with increasing x . These results are in good agreement with theoretical predictions and indicate the presence of prominent critical fluctuations at the TCP in this system.

Karube, K.; Hattori, T.; Ishida, K.; Kimura, N.

2015-02-01

223

Identification of Field Line Resonances in the Magnetosphere Using the Super Dual Auroral Radar Network (superdarn): New ``CROSS-POWER and Cross-Phase Technique  

NASA Astrophysics Data System (ADS)

Field Line Resonances (FLRs) are Ultra Low Frequency (ULF) standing waves that appear in discrete frequencies and occur in Earth’s Magnetic Field as a result of wave coupling of MHD compressional and Shear Alfvén waves. The main purpose of the new ‘cross-power and cross-phase’ technique, presented in this analysis, is to systematically identify FLR occurrence using data from the Super Dual Auroral Radar Network (SuperDARN), a radar network that detects coherent echoes from plasma irregularities that are aligned with the field lines. SuperDARN data has been successfully used for more than 17 years to identify FLRs, due to its large coverage over the polar cap and auroral region. Specifications of the instrument as well as the algorithm used by this new technique will be explained in detail. As an example we will apply the technique to a known 1.9 mHz FLR that occurred on November 20th 2003 at 22:30-23:00 UT detected by the Prince George station. Discussion of the application of this technique to automatically detect other events, and the future statistical analysis of all events identified will be presented.

Mazzino, L.; Fenrich, F. R.

2010-12-01

224

Surface-enhanced resonance Raman scattering (SERRS) spectroscopy: a powerful technique for the forensic analysis of colorants?  

Microsoft Academic Search

During the past five years work in our laboratory has been concentrated on developing SERRS spectroscopy and making it a simple and robust technique for the analyses of colorants. It has proved to be highly discriminative, extremely sensitive and possible to identify dyes in mixtures without their prior separation. Additionally, by using concentrated silver colloid solutions, in-situ analyses have now

Peter C. White; Caroline Rodger; Vicky Rutherford; Yvonne Finnon; W. Ewen Smith; Mary P. Fitzgerald

1999-01-01

225

H/D isotope effect of 1H MAS NMR spectra and 79Br NQR frequencies of piperidinium p-bromobenzoate and pyrrolidinium p-bromobenzoate  

NASA Astrophysics Data System (ADS)

H/D isotope effects onto 79Br NQR frequencies of piperidinium p-bromobenzoate were studied by deuterium substitution of hydrogen atoms which form two kinds of N-H?O type hydrogen bonds, and the isotope shift of ca. 100 kHz were detected for a whole observed temperature range. In addition, 1H MAS NMR spectra measurements of piperidinium and pyrrolidinium p-bromobenzoate were carried out and little isotope changes of NMR line shape were detected. In order to reveal effects of molecular arrangements into the obtained isotope shift of NQR frequencies, single-crystal X-ray measurement of piperidinium p-bromobenzoate- d2 and density-functional-theory calculation were carried out. Our estimation showed the dihedral-angle change between piperidine and benzene ring contributes to isotope shift rather than those of N-H lengths by deuterium substitution.

Honda, Hisashi; Kyo, Shinshin; Akaho, Yousuke; Takamizawa, Satoshi; Terao, Hiromitsu

2010-04-01

226

Three-Dimensional Mapping of Ozone-Induced Injury in the Nasal Airways of Monkeys Using Magnetic Resonance Imaging and Morphometric Techniques  

SciTech Connect

ABSTRACT Age-related changes in gross and microscopic structure of the nasal cavity can alter local tissue susceptibility as well as the dose of inhaled toxicant delivered to susceptible sites. This article describes a novel method for the use of magnetic resonance imaging, 3-dimensional airway modeling, and morphometric techniques to characterize the distribution and magnitude of ozone-induced nasal injury in infant monkeys. Using this method, we are able to generate age-specific, 3-dimensional, epithelial maps of the nasal airways of infant Rhesus macaques. The principal nasal lesions observed in this primate model of ozone-induced nasal toxicology were neutrophilic rhinitis, along with necrosis and exfoliation of the epithelium lining the anterior maxilloturbinate. These lesions, induced by acute or cyclic (episodic) exposures, were examined by light microscopy, quantified by morphometric techniques, and mapped on 3-dimensional models of the nasal airways. Here, we describe the histopathologic, imaging, and computational biology methods developed to efficiently characterize, localize, quantify, and map these nasal lesions. By combining these techniques, the location and severity of the nasal epithelial injury were correlated with epithelial type, nasal airway geometry, and local biochemical and molecular changes on an individual animal basis. These correlations are critical for accurate predictive modeling of exposure-dose-response relationships in the nasal airways, and subsequent extrapolation of nasal findings in animals to humans for developing risk assessment.

Carey, Stephen A.; Minard, Kevin R.; Trease, Lynn L.; Wagner, James G.; Garcia, Guilherme M.; Ballinger, Carol A.; Kimbell, Julia; Plopper, Charles G.; Corley, Rick A.; Postlewait, Ed; Harkema, Jack R.

2007-03-01

227

Miscibility of binary monolayers at the air-water interface and interaction of protein with immobilized monolayers by surface plasmon resonance technique.  

PubMed

The miscibility and stability of the binary monolayers of zwitterionic dipalmitoylphosphatidylcholine (DPPC) and cationic dioctadecyldimethylammonium bromide (DOMA) at the air-water interface and the interaction of ferritin with the immobilized monolayers have been studied in detail using surface pressure-area isotherms and surface plasmon resonance technique, respectively. The surface pressure-area isotherms indicated that the binary monolayers of DPPC and DOMA at the air-water interface were miscible and more stable than the monolayers of the two individual components. The surface plasmon resonance studies indicated that ferritin binding to the immobilized monolayers was primarily driven by the electrostatic interaction and that the amount of adsorbed protein at saturation was closely related not only to the number of positive charges in the monolayers but also to the pattern of positive charges at a given mole fraction of DOMA. The protein adsorption kinetics was determined by the properties of the monolayers (i.e., the protein-monolayer interaction) and the structure of preadsorbed protein molecules (i.e., the protein-protein interaction). PMID:16800676

Wang, Yuchun; Du, Xuezhong

2006-07-01

228

Contrast-enhanced breath-hold three-dimensional magnetic resonance angiography in the evaluation of renal arteries: optimization of technique and pitfalls.  

PubMed

The authors describe the optimization of a contrast-enhanced, breath-held, three-dimensional magnetic resonance angiography (CE-BH-3DMRA) technique in the assessment of the renal arteries and compare its utility with conventional x-ray angiography (XRA). Signal optimization using specific pulse sequence parameters was based on the patient's circulatory conditions, injection rate, and pulse sequence timing. Fifty-one patients (27 M, 24 F; mean age 69.7 years) were evaluated with CE-BH-3DMRA and XRA. All patients had an MR angiogram 3 months either before or after XRA. A test bolus study was performed for accurate assessment of transit time in each patient. A total of 51 patients (115 vessels) were studied in which the sensitivity and specificity for all renal artery stenoses including the proximal and mid-renal arterial segments were 96% and 92%, respectively. In-stent stenosis could only be diagnosed by quantifying flow beyond the stent using an additional triggered phase contrast cine pulse sequence. A total of 11 accessory renal arteries were correctly identified. In addition, fibromuscular dysplasia in two patients and stents in three patients were correctly identified on MRA. J. Magn. Reson. Imaging 2000;12:912-923. PMID:11105030

Shetty, A N; Bis, K G; Kirsch, M; Weintraub, J; Laub, G

2000-12-01

229

Non-contrast myocardial perfusion using a novel 4D magnetic resonance arterial spin labeling technique: Initial experience.  

PubMed

The aim of this study is to develop a novel non-contrast 4-dimensional MR arterial spin labeling (4D-ASL) technique (3D acquisition and time) and to investigate myocardial perfusion on healthy volunteers without administration of contrast materials. A non-contrast 4D-ASL technique was developed using the time-spatial labeling inversion pulse (Time-SLIP) to obtain myocardium perfusion of eight volunteers at 1.5T. The tagging slab was placed on the proximal ascending aorta to invert the blood magnetization and mid-ventricle 3D images at diastolic phase were acquired with multiple tagging delays. The time resolved 3D images with various inversion times (TI) were registered and segmented for the visualization of myocardial signal changes along the TI, and perfusion curves were generated to identify the perfusion peaks. Blood flow from basal to apical slices was observed in all volunteers. Peak flow at the mid-ventricle was observed 200-400ms after the blood was tagged at the aortic root blood. After the perfusion peak, all signals returned to the base line. The 4D Time-SLIP technique permits non-contrast perfusion images with high temporal resolution, which may potentially differentiate normal from diseased myocardium. PMID:25645290

Miyazaki, Mitsue; Zhou, Xiangzhi; Hoshino, Tsutomu; Yokoyama, Kenichi; Ishimura, Rieko; Nitatori, Toshiaki

2015-03-01

230

Target-triggering multiple-cycle amplification strategy for ultrasensitive detection of adenosine based on surface plasma resonance techniques.  

PubMed

An ultrasensitive protocol for surface plasma resonance (SPR) detection of adenosine is designed with the aptamer-based target-triggering cascade multiple cycle amplification, and streptavidin-coated Au-NPs (Au NPs-SA) enhancement to enhance the SPR signals. The cascade amplification process consists of the aptamer-based target-triggering nicking enzyme signaling amplification (T-NESA), the nicking enzyme signaling amplification (NESA) and the hybridization chain reaction (HCR), the entire circle amplification process is triggered by the target recognition of adenosine. Upon recognition of the aptamer to target adenosine, DNA s1 is released from the aptamer and then hybridizes with hairpin DNA (HP1). The DNA s1 can be dissociated from HP1 under the reaction of nicking endonuclease to initiate the next hybridization and cleavage process. Moreover, the products of the upstream cycle (T-NESA) (DNA s2 and s3) could act as the "DNA trigger" of the downstream cycle (NESA and HCR) to generate further signal amplification, resulting in the immobilization of abundant Au NPs-SA on the gold substrate, and thus significant SPR enhancement is achieved due to the electronic coupling interaction between the localized surface plasma of Au NPs and the surface plasma wave. This detection method exhibits excellent specificity and sensitivity toward adenosine with a detection limit of 4 fM. The high sensitivity and specificity make this method a great potential for detecting biomolecules with trace amounts in bioanalysis and clinical biomedicine. PMID:25494977

Yao, Gui-Hong; Liang, Ru-Ping; Yu, Xiang-Dan; Huang, Chun-Fang; Zhang, Li; Qiu, Jian-Ding

2015-01-20

231

Application of Polypyrrole Multi-Walled Carbon Nanotube Composite Layer for Detection of Mercury, Lead and Iron Ions Using Surface Plasmon Resonance Technique  

PubMed Central

Polypyrrole multi-walled carbon nanotube composite layers were used to modify the gold layer to measure heavy metal ions using the surface plasmon resonance technique. The new sensor was fabricated to detect trace amounts of mercury (Hg), lead (Pb), and iron (Fe) ions. In the present research, the sensitivity of a polypyrrole multi-walled carbon nanotube composite layer and a polypyrrole layer were compared. The application of polypyrrole multi-walled carbon nanotubes enhanced the sensitivity and accuracy of the sensor for detecting ions in an aqueous solution due to the binding of mercury, lead, and iron ions to the sensing layer. The Hg ion bonded to the sensing layer more strongly than did the Pb and Fe ions. The limitation of the sensor was calculated to be about 0.1 ppm, which produced an angle shift in the region of 0.3° to 0.6°. PMID:24733263

Sadrolhosseini, Amir Reza; Noor, A. S. M.; Bahrami, Afarin; Lim, H. N.; Talib, Zainal Abidin; Mahdi, Mohd. Adzir

2014-01-01

232

The analytical application and spectral investigation of DNA-CPB-emodin and sensitive determination of DNA by resonance Rayleigh light scattering technique  

NASA Astrophysics Data System (ADS)

A new sensitive DNA probe containing cetylpyridinium bromide (CPB) and emodin (an effective component of Chinese herbal medicine) was developed using the resonance Rayleigh light scattering (RLS) technique. A novel assay was first developed to detect DNA at nanogram level based on the ternary system of DNA-CPB-emodin. The RLS signal of DNA was enhanced remarkably in the presence of emodin-CPB, and the enhanced RLS intensity at 340.0 nm was in direct proportion to DNA concentration in the range of 0.01-2.72 ?g mL-1 with a good linear relationship. The detection limit was 1.5 ng mL-1. Three synthetic DNA samples were measured obtaining satisfactory results, the recovery was 97.6-107.3%.

Bi, Shuyun; Wang, Yu; Wang, Tianjiao; Pang, Bo; Zhao, Tingting

2013-01-01

233

Motion of Water Molecules and Hydrogen Bonds in Zinc Hexachlorostannate (IV) Hexahydrate as Studied by 1H NMR and 35Cl NQR  

NASA Astrophysics Data System (ADS)

The 1H NMR spin-lattice relaxation time T1, 35Cl NQR frequency ?Q, and 35Cl NQR spin-lattice relaxation time T1Q of [Zn(H2O)6] [SnCl6] (zinc hexachlorostannate(IV) hexahydrate) have been measured at temperatures between 77 and 350 K. The NQR spin echo signal with ?Q = 15.689 MHz at 77 K showed a positive temperature coefficient attributable to O-H-Cl type H-bonds in the crystal. ?Q at 77 K is strongly correlated with the electronegativity ?M of the metal M in the series of stannates [M(H2O)6] [SnCl6] (M = Mg, Ca, Mn, Co, Ni, Zn). A T1 minimum observed for the Zn salt is ascribed to 180° flips of water molecules with an activation energy of 20 kJ mol-1. The motion is influenced by repulsive forces among the water molecules within a cation rather than by attractive forces between the H-bonded H and CI atoms. T1Q proved to be mainly governed by lattice vibrations, weakly modulated by the fluctuating electric field gradient caused by the 180° flip motions.

Ishikawa, A.; Sasane, A.; Hirakawa, Y.; Mori, Y.

1996-06-01

234

Treatment of subclinical hyperthyroidism: effect on left ventricular mass and function of the heart using magnetic resonance imaging technique  

PubMed Central

Purpose The aim of this study was to investigate structure and function of the heart in subclinical hyperthyroidism (SH) before and after obtaining euthyroidism by radioactive iodine treatment, using high precision and observer-independent magnetic resonance imaging (MRI) technology. Methods Cardiac MRI was performed before and after euthyroidism was obtained by radioactive iodine treatment in 12 otherwise healthy patients (11 women and one man, mean age 59 years, range 44–71 years) with a nodular goiter and SH, and compared with eight healthy controls investigated at baseline. Cardiac data were expressed as an index, as per body surface area, except for heart rate (HR) and ejection fraction. Results Post-treatment cardiac MRI was performed in median 139 days after a normalized serum TSH value had been recorded. During treatment, serum TSH increased from (median (range)) 0.01 (0.01–0.09) to 0.88 (0.27–3.99) mU/l. Patients with untreated SH had increased resting HR (P<0.01) as well as cardiac index (cardiac output as per body surface area) (P<0.01) compared with controls. Obtaining euthyroidism resulted in a significant decrease in left ventricular mass index (LVMI) of 2.7?g/m2 (P=0.034), in HR of 8?bpm (P=0.001), and in cardiac index of 0.24?l/min per m2 (P=0.017). Conclusions Normalization of thyroid function by radioactive iodine treatment of SH resulted in significant reductions in clinically important heart parameters such as LVMI, HR, and cardiac index. SH should be regarded as a condition in which aggressive treatment should be considered to protect cardiac function. PMID:25568332

Mark, Peter D; Andreassen, Mikkel; Petersen, Claus L; Kjaer, Andreas; Faber, Jens

2015-01-01

235

Radical production from the interaction of ozone and PUFA as demonstrated by electron spin resonance spin-trapping techniques  

SciTech Connect

There is considerable evidence that indicates that a fraction of the damage caused by ozone to cellular systems involves radical-mediated reactions. The most direct method for probing the mechanism by which ozone reacts with target molecules such as polyunsaturated fatty acids involves the use of electron spin resonance. In 1968, Goldstein et al. reported that ESR signals were observed when 40 ppM ozone in air is bubbled through linoleic acid. We have repeated this experiment and have performed several experiments modified from this design; in none of these do we observe ESR signals. We have studied the reaction of ozone with PUFA at -78/sup 0/C using spin traps. Spin traps themselves react with ozone, but the following protocol avoids that reaction. (1) Ozone in air or oxygen-free ozone is allowed to bubble through the sample in Freon-11 in an ESR tube at -78/sup 0/C; no ESR absorption is observed. (2) Unreacted ozone is flushed out with argon or nitrogen. (3) The spin trap in Freon-11 is added to give a 0.1 M solution, still at -78/sup 0/C; no ESR signal is observed. (4) The tube is allowed to warm slowly. At about -45/sup 0/C, the ESR spectra of spin adducts appear. Using this method with methyl linoleate we observe spin adducts of alkoxy radicals and also a signal that is consistent with a carbon radical with one ..cap alpha..-H. We hypothesize that an intermediate is formed from the reaction of ozone with PUFA that is stable at -78/sup 0/Cbut decomposes to form radicals at about -45/sup 0/C. We tentatively identify the intermediate as a trioxide on the basis of analogies and its temperature profile for decomposition to radicals. It appears reasonable to suggest that the reaction(s) responsible for the production of radicals under these low-temperature conditions also occurs at room temperature. Although the low-temperature intermediate cannot be observed at ambient temperatures, radicals from it could be responsible for the effects on autoxidation that are induced by ozone.

Pryor, W.A.; Prier, D.G.; Church, D.F.

1981-02-01

236

Surface-enhanced resonance Raman scattering (SERRS) spectroscopy: a powerful technique for the forensic analysis of colorants?  

NASA Astrophysics Data System (ADS)

During the past five years work in our laboratory has been concentrated on developing SERRS spectroscopy and making it a simple and robust technique for the analyses of colorants. It has proved to be highly discriminative, extremely sensitive and possible to identify dyes in mixtures without their prior separation. Additionally, by using concentrated silver colloid solutions, in-situ analyses have now been accomplished with minimal or in some cases no visual destruction of the item being examined and with virtually no background interference from the surfaces on which the stains or smears have been deposited. To illustrate the methodology and the potential of SERRS various applications including the in-situ analyses of the dyes on cotton fibers and stains from cosmetics, shoe polishes, inks and drinks on various surfaces are presented.

White, Peter C.; Rodger, Caroline; Rutherford, Vicky; Finnon, Yvonne; Smith, W. Ewen; Fitzgerald, Mary P.

1999-02-01

237

Development of a label-free immunosensor based on surface plasmon resonance technique for the detection of anti-Leishmania infantum antibodies in canine serum.  

PubMed

In this work, a surface plasmon resonance (SPR) immunosensor was developed using an 11-mercaptoundecanoic acid (11-MUA) modified gold SPR sensor chip for the detection of anti-Leishmania infantum antibodies. The soluble antigens of L. infantum were securely immobilized on an SPR gold disk by an 11-MUA self-assembled monolayer. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM) techniques were employed in the characterization of the antigen immobilization. After the immunosensor construction, canine serum positive for visceral leishmaniasis was added to its surface and showed significant variation in the SPR angle, indicating excellent sensitivity of the technique for antigen-antibody interaction detection. Moreover, the addition of negative serum was accompanied by a smaller response, demonstrating that the immunosensor shows good specificity against anti-L. infantum antibodies. Therefore, this work demonstrates the successful development of an SPR sensor for anti-L. infantum antibodies detection in short time, showing a great perspective as a sensing system of visceral leishmaniasis in endemic regions. PMID:23500472

Souto, Dênio E P; Silva, Jussara V; Martins, Helen R; Reis, Alexandre B; Luz, Rita C S; Kubota, Lauro T; Damos, Flávio S

2013-08-15

238

In-NQR study of heavy fermion superconductor Ce2PdIn8 under pressure  

NASA Astrophysics Data System (ADS)

115In nuclear quadrupole resonance measurements were performed in the normal state of the heavy fermion superconductor Ce2PdIn8 under hydrostatic pressure up to about 2.3 GPa. The observed behavior of the spin-lattice relaxation rate revealed a systematic suppression of antiferromagnetic critical fluctuations with increasing pressure.

Fukazawa, Hideto; Shimatani, Sho; Shigeta, Kazuhiko; Kohori, Yoh; Kaczorowski, Dariusz

2015-03-01

239

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

240

Artificial neural network assisted kinetic spectrophotometric technique for simultaneous determination of paracetamol and p-aminophenol in pharmaceutical samples using localized surface plasmon resonance band of silver nanoparticles.  

PubMed

Spectrophotometric analysis method based on the combination of the principal component analysis (PCA) with the feed-forward neural network (FFNN) and the radial basis function network (RBFN) was proposed for the simultaneous determination of paracetamol (PAC) and p-aminophenol (PAP). This technique relies on the difference between the kinetic rates of the reactions between analytes and silver nitrate as the oxidizing agent in the presence of polyvinylpyrrolidone (PVP) which is the stabilizer. The reactions are monitored at the analytical wavelength of 420nm of the localized surface plasmon resonance (LSPR) band of the formed silver nanoparticles (Ag-NPs). Under the optimized conditions, the linear calibration graphs were obtained in the concentration range of 0.122-2.425?gmL(-1) for PAC and 0.021-5.245?gmL(-1) for PAP. The limit of detection in terms of standard approach (LODSA) and upper limit approach (LODULA) were calculated to be 0.027 and 0.032?gmL(-1) for PAC and 0.006 and 0.009?gmL(-1) for PAP. The important parameters were optimized for the artificial neural network (ANN) models. Statistical parameters indicated that the ability of the both methods is comparable. The proposed method was successfully applied to the simultaneous determination of PAC and PAP in pharmaceutical preparations. PMID:25528506

Khodaveisi, Javad; Dadfarnia, Shayessteh; Haji Shabani, Ali Mohammad; Rohani Moghadam, Masoud; Hormozi-Nezhad, Mohammad Reza

2015-03-01

241

Utility of SPM8 plus DARTEL (VSRAD) combined with magnetic resonance spectroscopy as adjunct techniques for screening and predicting dementia due to Alzheimer's disease in clinical practice.  

PubMed

We validated the utility of SPM8 plus DARTEL (VSRAD) combined with magnetic resonance spectroscopy (1H MRS) as an adjunct screening technique for dementia due to Alzheimer's disease (AD). We examined the posterior cingulate gyri of 228 subjects using VSRAD and 1H MRS in addition to conventional cerebrospinal fluid biomarkers at baseline. At the 3-year follow-up, the 228 subject were classified as follows: 93 healthy subjects, 42 MCI-non-converters (MCI-NC), 25 MCI-converters to AD (MCI-C), 44 AD, 8 dementia with Lewy bodies (DLB), 5 normal pressure hydrocephalus, and 11 patients with other neurological diseases. Our results demonstrated that subjects with increased medial temporal atrophy (MTA) severity on VSRAD, increased Cho/Cr, MI/Cr ratio, and decreased NAA/Cr and NAA/MI ratio on 1H MRS at baseline were at risk of dementia due to AD. Receiver operating characteristic analysis showed that severity of MTA and the NAA/MI ratio distinguished patients with AD and MCI-C from controls. Furthermore, the 118 subjects without dementia and MTA showing only a decreased NAA/MI ratio at baseline developed to MCI-C, AD, and DLB 3 years later. 1H MRS detected biochemical abnormalities preceding brain atrophy and cognitive decline. VSRAD combined with 1H MRS may be routinely applied to screen for MCI/AD and prodromal AD in clinical practice. PMID:24787913

Waragai, Masaaki; Hata, Saori; Suzuki, Toshiharu; Ishii, Ryotaro; Fujii, Chihiro; Tokuda, Takahiko; Arai, Hiroyuki; Ohrui, Takashi; Higuchi, Susumu; Yoshida, Madoka; Igarashi, Kazuei; Moriya, Masaru; Iwai, Naomichi; Uemura, Kenichi

2014-01-01

242

Artificial neural network assisted kinetic spectrophotometric technique for simultaneous determination of paracetamol and p-aminophenol in pharmaceutical samples using localized surface plasmon resonance band of silver nanoparticles  

NASA Astrophysics Data System (ADS)

Spectrophotometric analysis method based on the combination of the principal component analysis (PCA) with the feed-forward neural network (FFNN) and the radial basis function network (RBFN) was proposed for the simultaneous determination of paracetamol (PAC) and p-aminophenol (PAP). This technique relies on the difference between the kinetic rates of the reactions between analytes and silver nitrate as the oxidizing agent in the presence of polyvinylpyrrolidone (PVP) which is the stabilizer. The reactions are monitored at the analytical wavelength of 420 nm of the localized surface plasmon resonance (LSPR) band of the formed silver nanoparticles (Ag-NPs). Under the optimized conditions, the linear calibration graphs were obtained in the concentration range of 0.122-2.425 ?g mL-1 for PAC and 0.021-5.245 ?g mL-1 for PAP. The limit of detection in terms of standard approach (LODSA) and upper limit approach (LODULA) were calculated to be 0.027 and 0.032 ?g mL-1 for PAC and 0.006 and 0.009 ?g mL-1 for PAP. The important parameters were optimized for the artificial neural network (ANN) models. Statistical parameters indicated that the ability of the both methods is comparable. The proposed method was successfully applied to the simultaneous determination of PAC and PAP in pharmaceutical preparations.

Khodaveisi, Javad; Dadfarnia, Shayessteh; Haji Shabani, Ali Mohammad; Rohani Moghadam, Masoud; Hormozi-Nezhad, Mohammad Reza

2015-03-01

243

A novel method for study of the aggregation of protein induced by metal ion aluminum(III) using resonance Rayleigh scattering technique  

NASA Astrophysics Data System (ADS)

We present a novel method for the study of the aggregation of protein induced by metal ion aluminum(III) using resonance Rayleigh scattering (RRS) technique. In neutral Tris-HCl medium, the effect of this aggregation of protein results in the enhancement of RRS intensity and the relationship between the enhancement of the RRS signal and the Al concentration is nonlinear. On this basis, we established a new method for the determination of the critical induced-aggregation concentrations ( CCIAC) of metal ion Al(III) inducing the protein aggregation. Our results show that many factors, such as, pH value, anions, salts, temperature and solvents have obvious effects. We also studied the extent of aggregation and structural changes using ultra-violet spectrometry, protein intrinsic fluorescence and circular dichroism to further understand the exact mechanisms of the aggregation characteristics of proteins induced by metal ion Al(III) at the molecular level, to help us to develop effective methods to investigate the toxicity of metal ion Al, and to provide theoretical and quantitative evidences for the development of appropriate treatments for neurodementia such as Parkinson's disease, Alzheimer's disease and dementia related to dialysis.

Long, Xiufen; Zhang, Caihua; Cheng, Jiongjia; Bi, Shuping

2008-01-01

244

A novel and selective assay for the quantitative analysis of molybdenum(VI) at nanogram level by resonance light scattering quenching technique  

NASA Astrophysics Data System (ADS)

A novel method is designed for the direct determination of trace amounts of molybdenum(VI) in tap water, human hair, and Chinese herbal medicine by means of decreasing resonance light scattering (RLS) technique. The characteristics of RLS spectra, the effective factors, and optimum conditions of the reaction were studied. In the medium of hydrochloric acid (pH 2.38), Mo(VI), dibromohydroxyphenylfluorone (DBHPF), and Triton X-100 react to form a complex, resulting in significant decreasing RLS signals of DBHPF-Triton X-100. The decreasing RLS intensity at 583.0 nm is proportional to the concentration of Mo(VI) up to 8.0 ng mL -1. The detection limit is 0.013 ng mL -1. The method is simple, reproducible, with reaction rapidity and stability of complexes formed. Moreover, the high selectivity and sensitivity of this method permits its direct determination of molybdenum(VI) in tap water, human hair, and Chinese herbal medicine and the results are in agreement with those obtained by the inductively coupled plasma atomic emission spectrometry (ICP-AES) method.

Chen, Zhan Guang; Zhu, Li; Zhang, Tai Yu; Liu, Jin Bin; Han, Ya Li

2008-07-01

245

An investigation on the interaction of DNA with hesperetin/apigenin in the presence of CTAB by resonance Rayleigh light scattering technique and its analytical application  

NASA Astrophysics Data System (ADS)

Two new systems for measuring DNA at nanogram levels by a resonance Rayleigh light scattering (RLS) technique with a common spectrofluorometer were proposed. In the presence of cetyltrimethylammonium bromide (CTAB), the interaction of DNA with hesperetin and apigenin (two effective components of Chinese herbal medicine) could enhance RLS signals with the maximum peak at 363 and 433 nm respectively. The enhanced intensity of RLS was directly proportional to the concentration of DNA in the range of 0.022-4.4 ?g mL-1 for DNA-CTAB-hesperetin system and 0.013-4.4 ?g mL-1 for DNA-CTAB-apigenin system. The detection limit was 2.34 ng mL-1 and 2.97 ng mL-1 respectively. Synthetic samples were measured satisfactorily. The recovery of DNA-CTAB-hesperetin system was 97.3-101.9% and that of DNA-CTAB-apigenin system was 101.2-109.5%.

Bi, Shuyun; Wang, Yu; Pang, Bo; Yan, Lili; Wang, Tianjiao

2012-05-01

246

Comparison of the different responses of surface plasmon resonance and quartz crystal microbalance techniques at solid-liquid interfaces under various experimental conditions.  

PubMed

A molecular level understanding of the phenomena taking place at solid-liquid interfaces, ranging from changes in mass to conformation changes, is the key to developing and improving many chemical and biological systems and their scientific and medical applications. Surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) techniques are often coupled to achieve this understanding. We divided various experimentally relevant scenarios into the following six categories: boundary solutions; surface modifications; conformation; viscoelastic properties; molecular ruler; and mass sensitivity. For each case, based on theoretical analyses, we discuss the following four points with respect to discrete adsorbates at solid-liquid interfaces: (1) the different types of information that can be obtained, why it can be obtained and how to obtain it; (2) the origins of many current approaches and why they are imperfect; (3) guidelines for experimental design; and (4) possible studies, such as the effect of dimensional confinement and adsorption forces on the ability of conformational changes to occur on the receipt of external stimuli and the hysteresis in these changes. PMID:25575354

Fang, Jiajie; Ren, Chunlai; Zhu, Tao; Wang, Kaiyu; Jiang, Zhongying; Ma, Yuqiang

2015-02-21

247

Nuclear magnetic resonance experiments with dc SQUID amplifiers  

SciTech Connect

The development and fabrication of dc SQUIDs (Superconducting QUantum Interference Devices) with Nb/Al{sub 2}O{sub 3}/Nb Josephson junctions is described. A theory of the dc SQUID as a radio-frequency amplifier is presented, with an optimization strategy that accounts for the loading and noise contributions of the postamplifier and maximizes the signal-to-noise ratio of the total system. The high sensitivity of the dc SQUID is extended to high field NMR. A dc SQUID is used as a tuned radio-frequency amplifier to detect pulsed nuclear magnetic resonance at 32 MHz from a metal film in a 3.5 Tesla static field. A total system noise temperature of 11 K has been achieved, at a bath temperature of 4.2 K. The minimum number of nuclear Bohr magnetons observable from a free precession signal after a single pulse is about 2 {times} 10{sup 17} in a bandwidth of 25 kHz. In a separate experiment, a dc SQUID is used as a rf amplifier in a NQR experiment to observe a new resonance response mechanism. The net electric polarization of a NaClO{sub 3} crystal due to the precessing electric quadrupole moments of the Cl nuclei is detected at 30 MHz. The sensitivity of NMR and NQR spectrometers using dc SQUID amplifiers is compared to the sensitivity of spectrometers using conventional rf amplifiers. A SQUID-based spectrometer has a voltage sensitivity which is comparable to the best achieved by a FET-based spectrometer, at these temperatures and operating frequencies.

Heaney, M.B. (California Univ., Berkeley, CA (USA). Dept. of Physics Lawrence Berkeley Lab., CA (USA))

1990-11-01

248

Topology of the interactions pattern in pharmaceutically relevant polymorphs of methylxanthines (caffeine, theobromine, and theophiline): combined experimental (¹H-¹?N nuclear quadrupole double resonance) and computational (DFT and Hirshfeld-based) study.  

PubMed

Three anhydrous methylxanthines: caffeine (1,3,7-trimethylxanthine; 1,3,7-trimethyl-1H-purine-2,6-(3H,7H)-dione) and its two metabolites theophylline (1,3-dimethylxanthine; 1,3-dimethyl-7H-purine-2,6-dione) and theobromine (3,7-dimethyl-xanthine; 3,7-dimethyl-7H-purine-2,6-dione), which reveal multifaceted therapeutic potential, have been studied experimentally in solid state by (1)H-(14)N NMR-NQR (nuclear magnetic resonance-nuclear quadrupole resonance) double resonance (NQDR). For each compound the complete NQR spectrum consisting of 12 lines was recorded. The multiplicity of NQR lines indicates the presence of a stable ? form of anhydrous caffeine at 233 K and stable form II of anhydrous theobromine at 213 K. The assignment of signals detected in NQR experiment to particular nitrogen atoms was made on the basis of quantum chemistry calculations performed for monomer, cluster, and solid at the DFT/GGA/BLYP/DPD level. The shifts due to crystal packing interactions were evaluated, and the multiplets detected by NQR were assigned to N(9) in theobromine and N(1) and N(9) in caffeine. The ordering theobromine > theophylline > caffeine site and theophylline < theobromine < caffeine according to increasing electric field gradient (EFG) at the N(1) and N(7) sites, respectively, reflects the changes in biological activity profile of compounds from the methylxanthines series (different pharmacological effects). This difference is elucidated on the basis of the ability to form intra- and intermolecular interactions (hydrogen bonds and ?···? stacking interactions). The introduction of methyl groups to xanthine restricts the ability of nitrogen atoms to participate in strong hydrogen bonds; as a result, the dominating effect shifts from hydrogen bond (theobromine) to ?···? stacking (caffeine). Substantial differences in the intermolecular interactions in stable forms of methylxanthines differing in methylation (site or number) were analyzed within the Hirshfeld surface-based approach. The analysis of local environment of the nitrogen nucleus permitted drawing some conclusions on the nature of the interactions required for effective processes of recognition and binding of a given methylxanthine to A1-A(2A) receptor (target for caffeine in the brain). Although the interactions responsible for linking neighboring methylxanthines molecules in crystals and methylxanthines with targets in the human organism can differ significantly, the knowledge of the topology of interactions provides reliable preliminary information about the nature of this binding. PMID:25184363

Latosi?ska, Jolanta Natalia; Latosi?ska, Magdalena; Olejniczak, Grzegorz A; Seliger, Janez; Žagar, Veselko

2014-09-22

249

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

250

Comparison of Different Magnetic Resonance Cholangiography Techniques in Living Liver Donors Including Gd-EOB-DTPA Enhanced T1-Weighted Sequences  

PubMed Central

Objectives Preoperative evaluation of potential living liver donors (PLLDs) includes the assessment of the biliary anatomy to avoid postoperative complications. Aim of this study was to compare T2-weighted (T2w) and Gd-EOB-DTPA enhanced T1-weighted (T1w) magnetic resonance cholangiography (MRC) techniques in the evaluation of PLLDs. Materials and Methods 30 PLLDs underwent MRC on a 1.5 T Magnetom Avanto (Siemens, Erlangen, Germany) using (A) 2D T2w HASTE (Half Fourier Acquisition Single Shot Turbo Spin Echo) fat saturated (fs) in axial plane, (B) 2D T2w HASTE fs thick slices in coronal plane, (C) free breathing 3D T2w TSE (turbo spin echo) RESTORE (high-resolution navigator corrected) plus (D) maximum intensity projections (MIPs), (E) T2w SPACE (sampling perfection with application optimized contrasts using different flip angle evolutions) plus (F) MIPs and (G) T2w TSE BLADE as well as Gd-EOB-DTPA T1w images without (G) and with (H) inversion recovery. Contrast enhanced CT cholangiography served as reference imaging modality. Two independent reviewers evaluated the biliary tract anatomy on a 5-point scale subjectively and objectively. Data sets were compared using a Mann-Whitney-U-test. Kappa values were also calculated. Results Source images and maximum intensity projections of 3D T2w TSE sequences (RESTORE and SPACE) proved to be best for subjective and objective evaluation directly followed by 2D HASTE sequences. Interobserver variabilities were good to excellent (k?=?0.622–0.804). Conclusions 3D T2w sequences are essential for preoperative biliary tract evaluation in potential living liver donors. Furthermore, our results underline the value of different MRCP sequence types for the evaluation of the biliary anatomy in PLLDs including Gd-EOB-DTPA enhanced T1w MRC. PMID:25426932

Kinner, Sonja; Steinweg, Verena; Maderwald, Stefan; Radtke, Arnold; Sotiropoulos, Georgios; Forsting, Michael; Schroeder, Tobias

2014-01-01

251

Stochastic Resonance  

NASA Astrophysics Data System (ADS)

Preface; 1. Introduction and motivation; 2. Stochastic resonance: its definitions, history and debates; 3. Stochastic quantization; 4. Suprathreshold stochastic resonance: encoding; 5. Suprathreshold stochastic resonance: large N encoding; 6. Suprathreshold stochastic resonance: decoding; 7. Suprathreshold stochastic resonance: large N decoding; 8. Optimal stochastic quantization; 9. SSR, neural coding, and performance tradeoffs; 10. Stochastic resonance in the auditory system; 11. The future of stochastic resonance and suprathreshold stochastic resonance; Appendices; References; Index.

McDonnell, Mark D.; Stocks, Nigel G.; Pearce, Charles E. M.; Abbott, Derek

2012-10-01

252

Immediate effect of mind sound resonance technique on state anxiety and cognitive functions in patients suffering from generalized anxiety disorder: A self-controlled pilot study  

PubMed Central

Objectives: To compare the immediate effect of mind sound resonance technique (MSRT) with supine rest (SR) on state anxiety and psychomotor performance in 15 (eight male and seven female) right-handed generalized anxiety disorder patients (GAD) with an age range of 34.8 ± 12.8 years. Materials and Methods: Self as control design was followed. Diagnosis of GAD was made by a psychiatrist using sections of the Mini International Neuropsychiatric Interview (MINI). Participants practiced MSRT or SR (as control intervention) for 30 min at the same time for two consecutive days. The sequence of intervention was assigned randomly to the participants. State anxiety was assessed using state trait anxiety inventory (STAI; Form X1). Digit letter substitution task (DLST) was used to assess psychomotor performance, which involves visual scanning, mental flexibility, sustained attention, psychomotor speed and speed of information processing. Intervention was given in a quiet dark room on an empty stomach. Subjects received a training of MSRT and SR for 1 week before the data were taken. A pre-recorded audiotape was used to administer the technique of MSRT. Difference in scores after baseline and intervention was used to check normality, and was found to be normally distributed by the Kolmogrov–Smirnov test. The changes in STAI, DLST and difference in scores before and after two interventions (MSRT and SR) were compared using the paired samples t test. Results: As compared with baseline, STAI scores reduced and DLST scores increased significantly (STAI; P < 0.01; DLST; P < 0.01) after MSRT. After SR, there was a significant reduction in STAI scores from baseline (STAI; P < 0.05), but there was no significant change in the DLST scores (P = 0.26). Comparison of the difference in scores for DLST and STAI before and after the two interventions (MSRT and SR) showed a significantly higher score for DLST (P < 0.05) and a significantly lower score for STAI (P < 0.01) for MSRT as compared with SR. Conclusion: This pilot study suggests that MSRT may have a potential role in reducing state anxiety and enhancing psychomotor performance in patients suffering from GAD immediately after the practice. These findings need confirmation from studies with a larger sample size and randomized controlled design, which are implicated in the future. PMID:25558137

Dhansoia, Vipin; Bhargav, Hemant; Metri, Kashinath

2015-01-01

253

Kinetics of electrochemically controlled surface reactions on bulk and thin film metals studied with Fourier transform impedance spectroscopy and surface plasmon resonance techniques  

NASA Astrophysics Data System (ADS)

In the work presented in this thesis, the surface sensitive electrochemical techniques of cyclic voltametry (CV), potential step (PS) and Fourier transform impedance spectroscopy (FT-EIS), as well as the optical technique of surface plasmon resonance (SPR), were used to probe a wide variety of surface processes at various metal/liquid interface. Three polycrystalline metals (Au, Ta and Cu) and a Cr-coated gold film were used for these studies in different aqueous environments. A combination of CV with FT-EIS and PS was used to investigate electronic and structural proprieties of a modified bulk electrode of Au. This experimental system involved under potential deposition (UPD) of Bi3+ on Au in a supporting aqueous electrolyte containing ClO-4 . UPD range of Bi3+ was determined, and adsorption kinetics of Bi3+ in the presence of coadsorbing anion, ClO-4 were quantified. Potentiodynamic growth of oxide films of Ta in the following electrolytes NaNO3, NaNO3 + 5wt% H2O2, NaOH and NaOH + 5wt% H2O2 had been investigated. The oxide films were grown in the range -0.1 ? +0.4V (high electric field) at a scan rate of 10 mV/s. Time resolved A.C. impedance spectroscopy measurements in the frequency range (0.1--20 KHz) were performed to characterize the surface reactions of oxide formation. The results are interpreted in terms of charge conductivity O2- through the oxide film, and disintegration of H2O2 into OH-. In a high pH medium (pH 12), dissociation of H2O2 was catalytically enhanced. This led to destabilization of the electrogenerated tantalum oxide surface film in the form of a soluble hexatantalate species. In contrast with the electrolytes, NaNO3, NaNO3 + 5wt% H2O2, NaOH, where only the oxide growth was observed, the A.C. impedance spectroscopy measurements in NaOH + 5wt% H 2O2 showed competition between oxide formation and its removal. These results are relevant for chemical slurry design in chemical mechanical polishing (CMP) of Ta. Further investigations were performed by studying potential galvanic corrosion effects that are susceptible to occur during planarization process in CMP technology. A combination of FT-EIS with potentiodynamic polarization and galvanic current measurements showed evidence of these effects when Cu (interconnected material in integrated circuits) and Ta (barrier material) were brought into electrical contact via abrasive-free polishing solutions. Quantitative analyses of kinetics of these effects were performed. Catalytic activity of a thin film Au (˜40 nm) toward methanol oxidation in alkaline medium for direct methanol fuel cell (DMFC) was carried out in this part of the work. A relatively unique combined technique of FT-EIS and SPR was used to perform this study. The FT-EIS data provided detailed kinetic parameters that characterize electro-oxidation of methanol. This led to a quantitative understanding of the mechanism of the probed surface reactions. At the same time, the SPR data provided with high accuracy the optical parameters and electronic characteristics of the thin film Au. The combined technique provided a complete understanding of the observed surface reactions, and showed consistency in data.

Assiongbon, Kankoe A.

2005-07-01

254

Perturbed open resonators.  

PubMed

The resonant frequencies and diffraction losses of two-mirror open resonators which depart somewhat from an ideal configuration are evaluated by a perturbative technique. Detailed results are derived and discussed for flat mirrors of rectangular or circular aperture with a parabolic phase perturbation as well as flat-roof and conical systems with large apex angle. PMID:20094565

Barone, S R

1971-04-01

255

Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Instrumentation and Methods for Structural Characterization of Trapped Biomolecular Ions: Innovative MS\\/MS Techniques, Gas-Phase Hudrogen\\/Deuterium Exchange, and Laser-Induced Fluoresnence  

Microsoft Academic Search

Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has become a powerful tool for biomolecular structural characterization because of its superior mass resolving power and high mass accuracy. Of particular interest in this work is the optimization of the diverse range of fragmentation techniques available to FT-ICR MS\\/MS, including ion threshing, a novel form of collisionally activated dissociation (CAD),

Melinda A. McFarland

2004-01-01

256

NQR investigation of pressure-induced charge transfer in oxygen-deficient YBa sub 2 Cu sub 3 O sub 7-. delta. (. delta. = 0. 38)  

SciTech Connect

Measurements of the pressure dependence of {sup 63}Cu nuclear quadrupole frequency in YBa{sub 2}Cu{sub 3}O{sub 6.62} from ambient pressure up to 1.5 GPa at 4k have been performed. {Tc} was found to increase with pressure: d{Tc}/dp {approximately} 5 K/GPa. All observed NQR lines are linear in pressure: dln{nu}{sub Q}/dp=z. We found positive z for the empty chain sites, consistent with ionic (Cu{sup 1+}) configuration in which the atom simply feels a squeezing lattice. Planar coppers close to the empty chains have positive z, while those that are close to full chains have z {approximately} 0. We present an analysis of the NQR result on the basis of the charge transfer model in which the mobile charges migrate from the chain to the plane sites. We deduced that a transfer of 0.021 holes to the O(2,3) sites would explain the result in YBa{sub 2}Cu{sub 3}O{sub 6.62}, whereas only 0.007 holes transfer in fully oxygenated YBa{sub 2}Cu{sub 3}O{sub 7}.

Reyes, A.P.; Ahrens, E.T.; Hammel, P.C.; Heffner, R.H. (Los Alamos National Lab., NM (United States)); Takigawa, M. (International Business Machines Corp., Yorktown Heights, NY (United States). Thomas J. Watson Research Center)

1992-01-01

257

Sodium Magnetic Resonance Imaging of Ankle Joint in Cadaver Specimens, Volunteers, and Patients After Different Cartilage Repair Techniques at 7 T  

PubMed Central

Objectives The goal of cartilage repair techniques such as microfracture (MFX) or matrix-associated autologous chondrocyte transplantation (MACT) is to produce repair tissue (RT) with sufficient glycosaminoglycan (GAG) content. Sodium magnetic resonance imaging (MRI) offers a direct and noninvasive evaluation of the GAG content in native cartilage and RT. In the femoral cartilage, this method was able to distinguish between RTs produced by MFX and MACT having different GAG contents. However, it needs to be clarified whether sodium MRI can be useful for evaluating RT in thin ankle cartilage. Thus, the aims of this 7-T study were (1) to validate our sodium MRI protocol in cadaver ankle samples, (2) to evaluate the sodium corrected signal intensities (cSI) in cartilage of volunteers, (3) and to compare sodium values in RT between patients after MFX and MACT treatment. Materials and Methods Five human cadaver ankle samples as well as ankles of 9 asymptomatic volunteers, 6 MFX patients and 6 MACT patients were measured in this 7-T study. Sodium values from the ankle samples were compared with histochemically evaluated GAG content. In the volunteers, sodium cSI values were calculated in the cartilages of ankle and subtalar joint. In the patients, sodium cSI in RT and reference cartilage were measured, morphological appearance of RT was evaluated using the magnetic resonance observation of cartilage repair tissue (MOCART) scoring system, and clinical outcome before and after surgery was assessed using the American Orthopaedic Foot and Ankle Society score and Modified Cincinnati Knee Scale. All regions of interest were defined on morphological images and subsequently transferred to the corresponding sodium images. Analysis of variance, t tests, and Pearson correlation coefficients were evaluated. Results In the patients, significantly lower sodium cSI values were found in RT than in reference cartilage for the MFX (P = 0.007) and MACT patients (P = 0.008). Sodium cSI and MOCART scores in RT did not differ between the MFX and MACT patients (P = 0.185). No significant difference in sodium cSI was found between reference cartilage of the volunteers and the patients (P = 0.355). The patients showed significantly higher American Orthopaedic Foot and Ankle Society and Modified Cincinnati scores after treatment than they did before treatment. In the volunteers, sodium cSI was significantly higher in the tibial cartilage than in the talar cartilage of ankle joint (P = 0.002) and in the talar cartilage than in the calcaneal cartilage of subtalar joint (P < 0.001). Data from the cadaver ankle samples showed a strong linear relationship between the sodium values and the histochemically determined GAG content (r = 0.800; P < 0.001; R2 = 0.639). Conclusions This study demonstrates the feasibility of in vivo quantification of sodium cSI, which can be used for GAG content evaluation in thin cartilages of ankle and subtalar joints at 7 T. A strong correlation observed between the histochemically evaluated GAG content and the sodium values proved the sufficient sensitivity of sodium MRI to changes in the GAG content of cartilages in the ankle. Both MFX and MACT produced RT with lower sodium cSI and, thus, of lower quality compared with reference cartilage in the patients or in the volunteers. Our results suggest that MFX and MACT produce RT with similar GAG content and similar morphological appearance in patients with similar surgery outcome. Sodium MRI at 7 T allows a quantitative evaluation of RT quality in the ankle and may thus be useful in the noninvasive assessment of new cartilage repair procedures. PMID:25436618

Zbý?, Štefan; Brix, Martin O.; Juras, Vladimir; Domayer, Stephan E.; Walzer, Sonja M.; Mlynarik, Vladimir; Apprich, Sebastian; Buckenmaier, Kai; Windhager, Reinhard; Trattnig, Siegfried

2015-01-01

258

Appl. Magn. Reson. 28, 1XXX (2005) Magnetic Resonance  

E-print Network

Appl. Magn. Reson. 28, 1XXX (2005) Applied Magnetic Resonance © Springer-Verlag 2005 Printed-based functional magnetic resonance imaging (fMRI) techniques have proven to be extremely robust and sensitive firing spatially and temporally integrates on the spatial scale of an MRI voxel to produce a magnetic

Baker, Chris I.

259

Coulomb disorder effects on angle-resolved photoemission and nuclear quadrupole resonance spectra in cuprates  

NASA Astrophysics Data System (ADS)

The role of Coulomb disorder, either of extrinsic origin or introduced by dopant ions in undoped and lightly doped cuprates, is studied. We demonstrate that charged surface defects in an insulator lead to a Gaussian broadening of the angle-resolved photoemisson spectroscopy (ARPES) lines. The effect is due to the long-range nature of the Coulomb interaction. A tiny surface concentration of defects about a fraction of one percent is sufficient to explain the line broadening observed in Sr2CuO2Cl2 , La2CuO4 , and Ca2CuO2Cl2 . Due to the Coulomb screening, the ARPES spectra evolve dramatically with doping, changing their shape from a broad Gaussian form to narrow Lorentzian ones. To understand the screening mechanism and the line-shape evolution in detail, we perform Hartree-Fock simulations with random positions of surface defects and dopant ions. To check validity of the model we calculate the nuclear quadrupole resonance (NQR) line shapes as a function of doping and reproduce the experimentally observed NQR spectra. Our study also indicates opening of a substantial Coulomb gap at the chemical potential. For a surface CuO2 layer the value of the gap is on the order of 10 meV while in the bulk it is reduced to the value about a few meV.

Chen, Wei; Khaliullin, Giniyat; Sushkov, Oleg P.

2009-09-01

260

High frequency STW resonator filters  

Microsoft Academic Search

The authors present results obtained in the 1-GHz-2-GHz region for surface transverse wave (STW) resonator filters implemented using inline coupled (RFI) and combined mode resonator filter (CMRF) techniques. The STW device performance is strongly dependent on the surface confinement of the acoustic wave. In an inline resonator filter the inner grating serves the dual purpose of trapping the energy near

R. Almar; B. Horine; J. Andersen

1992-01-01

261

NQR Investigation of Anion Dynamics in Rb2Zn(Cl1 - xBrx)4  

NASA Astrophysics Data System (ADS)

The structural stability of Rb2Zn(Cl1 - xBrx)4 (x = 1% and 3%) is investigated using the 35Cl quadrupole resonance frequency and spin lattice relaxation time (T1Q) in the paraelectric (PE) phase. The PE to incommensurate (IC) phase transition temperature T1, observed at 302 K in the pure compound, is lowered to 300 K for x = 1 % and to 293 K for x = 3%. These effects are smaller than in the earlier reported case of 3% Cs substitution in Rb2ZnCl4 , which reduces T1 by 25 K. While bigger cation substitution affects only the barrier for anion dynamics about directions perpendicular to the a-axis (direction of low temperature IC modulation wave), bigger anion substitution is found to affect the barrier for anion dynamics about the a-axis as well. The present study also indicates that the cusp like dip in T1Q observed while approaching T1 from above (characterizing the soft mode condensation associated with the structural phase transition) is essentially unaffected by anion impurity substitution, in contrast to the case where bigger cation substitution tends to smear the transitional effects. These results seem to suggest the dominant role played by cations in stabilizing the PE phase of these A2BX4 systems, in comparison to anions.

Subramanian, R. K.; Maheswari, S. Uma; Venu, K.; Sastry, V. S. S.

1996-06-01

262

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

E-print Network

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

Hammel, P. Chris

263

Wirelessly sensing resonant frequency of passive resonators with different Q factors  

Microsoft Academic Search

This paper presents a method of wirelessly sensing the resonant frequency of passive resonators using modulated waveforms. A pulse signal with a relatively wide frequency spectrum is transmitted towards a passive resonator, which in turn, reflects energy back to the interrogator. After time-domain gating and processing, the resonant frequency of the passive resonator can be wireless detected. This technique can

Mathew Lukacs; Xinhua Ren; Xun Gong

2011-01-01

264

Excited-state charge transfer dynamics in systems of aromatic adsorbates on TiO2 studied with resonant core techniques  

NASA Astrophysics Data System (ADS)

Resonant core spectroscopies are applied to a study of the excited electron transfer dynamics on a low-femtosecond time scale in systems of aromatic molecules (isonicotinic acid and bi-isonicotinic acid) adsorbed on a rutile TiO2(110) semiconductor surface. Depending on which adsorbate state is excited, the electron is either localized on the adsorbate in an excitonic effect, or delocalizes rapidly into the substrate in less than 5 fs (3 fs) for isonicotinic acid (bi-isonicotinic acid). The results are obtained by the application of a variant of resonant photoemission spectroscopy.

Schnadt, J.; O'Shea, J. N.; Patthey, L.; Kjeldgaard, L.; Åhlund, J.; Nilson, K.; Schiessling, J.; Krempaský, J.; Shi, M.; Karis, O.; Glover, C.; Siegbahn, H.; Mârtensson, N.; Brühwiler, P. A.

2003-12-01

265

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

266

Application of nuclear quadrupole resonance in study of minerals  

Microsoft Academic Search

The NQR method has been used to study some structural and chemical properties of minerals that are difficult or impossible to determine by conventional methods. For example, an X-ray determination commonly integrates the data for all cells, whereas NQR can separate the nearly ideal from highly distorted ones. It can thus give a better picture of the ideal structure and

I. N. Penkov; I. A. Sofin

1967-01-01

267

Resonance Ionization, Mass Spectrometry.  

ERIC Educational Resources Information Center

Discussed is an analytical technique that uses photons from lasers to resonantly excite an electron from some initial state of a gaseous atom through various excited states of the atom or molecule. Described are the apparatus, some analytical applications, and the precision and accuracy of the technique. Lists 26 references. (CW)

Young, J. P.; And Others

1989-01-01

268

Functional Magnetic Resonance Imaging  

ERIC Educational Resources Information Center

Functional magnetic resonance imaging (fMRI), with its excellent spatial resolution and ability to visualize networks of neuroanatomical structures involved in complex information processing, has become the dominant technique for the study of brain function and its development. The accessibility of in-vivo pediatric brain-imaging techniques…

Voos, Avery; Pelphrey, Kevin

2013-01-01

269

Tuned Spiral Resonators for Composite Metamaterials  

Microsoft Academic Search

Metamaterials composed of thin wires and spiral resonators have been studied in this paper. Technique to tune spiral resonators have been proposed. Transmission and reflection properties of metamaterials composed of thin wires and tuned spiral resonators have been simulated and compared with conventional metamaterials. The center frequency and transmission bandwidth of metamaterials have been varied through tuning of spiral resonators

M. Faisal Khan; M. Junaid Mughal

2006-01-01

270

Multinuclear NMR/NQR study of HgBa 2CuO 4+ xF y superconductors with different oxygen and fluorine content  

NASA Astrophysics Data System (ADS)

We have measured 63,65Cu NMR/NQR spectra, 199Hg and 19F NMR spectra and spin-lattice relaxation rate on a series of powder HgBa 2CuO 4+ xF y samples with different oxygen and fluorine content. Comparison of 63Cu and 199Hg relaxation data to numerical calculations for several types of the order parameter symmetry gives the best coincidence with the d-wave symmetry. 19F NMR line width and relaxation rate are strongly influenced by the magnetic flux-line motion. The 19F magnetization recovery curve is described by a stretched exponential function. The 19F spin-lattice relaxation strongly depends on the fluorine content evidencing that at higher doping level part of F atoms occupy the apical O2 position.

Gippius, A. A.; Antipov, E. V.; Klein, O.; Lüders, K.

2000-07-01

271

Binding of Tamm-Horsfall protein to complement 1q measured by ELISA and resonant mirror biosensor techniques under various ionic-strength conditions  

Microsoft Academic Search

The purpose of the present study was to quantify the binding affinity between Tamm-Horsfall protein (THP) and complement 1q (C1q) using ELISA and a resonant mirror biosensor. In ELISA, immobilized THP was incubated with soluble C1q under both low and physiological ionic-strength conditions. Tamm-Horsfall protein bound C1q with an equilibrium dissociation constant (KD) of 1.9 ± 0.6 nmol\\/L in low

Diana C J Rhodes; Diana CJ Rhodes

2000-01-01

272

Injection-controlled laser resonator  

DOEpatents

A new injection-controlled laser resonator incorporates self-filtering and self-imaging characteristics with an efficient injection scheme. A low-divergence laser signal is injected into the resonator, which enables the injection signal to be converted to the desired resonator modes before the main laser pulse starts. This injection technique and resonator design enable the laser cavity to improve the quality of the injection signal through self-filtering before the main laser pulse starts. The self-imaging property of the present resonator reduces the cavity induced diffraction effects and, in turn, improves the laser beam quality.

Chang, Jim J. (Dublin, CA)

1995-07-18

273

Injection-controlled laser resonator  

DOEpatents

A new injection-controlled laser resonator incorporates self-filtering and self-imaging characteristics with an efficient injection scheme. A low-divergence laser signal is injected into the resonator, which enables the injection signal to be converted to the desired resonator modes before the main laser pulse starts. This injection technique and resonator design enable the laser cavity to improve the quality of the injection signal through self-filtering before the main laser pulse starts. The self-imaging property of the present resonator reduces the cavity induced diffraction effects and, in turn, improves the laser beam quality. 5 figs.

Chang, J.J.

1995-07-18

274

Comparison of semi-automated scar quantification techniques using high-resolution, 3-dimensional late-gadolinium-enhancement magnetic resonance imaging.  

PubMed

The quantification and modeling of myocardial scar is of expanding interest for image-guided therapy, particularly in the field of arrhythmia management. Migration towards high-resolution, three-dimensional (3D) MRI techniques for spatial mapping of myocardial scar provides superior spatial registration. However, to date no systematic comparison of available approaches to 3D scar quantification have been performed. In this study we compare the reproducibility of six 3D scar segmentation algorithms for determination of left ventricular scar volume. Additionally, comparison to two-dimensional (2D) scar quantification and 3D manual segmentation is performed. Thirty-five consecutive patients with ischemic cardiomyopathy were recruited and underwent conventional 2D late gadolinium enhancement (LGE) and 3D isotropic LGE imaging (voxel size 1.3 mm(3)) using a 3 T scanner. 3D LGE datasets were analyzed using six semi-automated segmentation techniques, including the signal threshold versus reference mean (STRM) technique at >2, >3, >5 and >6 standard deviations (SD) above reference myocardium, the full width at half maximum (FWHM) technique, and an optimization-based technique called hierarchical max flow (HMF). The mean ejection fraction was 32.1 ± 12.7 %. Reproducibility was greatest for HMF and FWHM techniques with intra-class correlation coefficient values ?0.95. 3D scar quantification and modeling is clinically feasible in patients with ischemic cardiomyopathy. While several approaches show acceptable reproducibility, HMF appears superior due to maintenance of accuracy towards manual segmentations. PMID:25307896

Rajchl, Martin; Stirrat, John; Goubran, Maged; Yu, Jeff; Scholl, David; Peters, Terry M; White, James A

2015-02-01

275

Scanning thermal microwave resonance microscopy  

NASA Astrophysics Data System (ADS)

Local detection of ferromagnetic resonance in magnetically ordered materials is achieved by local thermal modulation of the microwave resonance absorption with a scanning thermal microscope. A scanning thermal microwave resonance microscope was constructed based on a microwave bridge with an X-band cavity and a thermal nano-probe contacted to the sample at the wall of the cavity. The technique has been tested on an epitaxial iron film which exhibited lateral inhomogeneities due to a partial oxidation of iron. Different types of oxidation could be distinguished. The locally resolved ferromagnetic resonance spectra are compared with the result of an integral measurement using conventional detection techniques of the ferromagnetic resonance with the same set-up. The lateral resolution achievable with the thermally modulated ferromagnetic resonance measurements was about 200 nm for the investigated iron film.

Meckenstock, R.; Spoddig, D.; Dietzel, D.; Pelzl, J.

2004-03-01

276

Morphological resonances for multicomponent immunoassays  

SciTech Connect

An immunoassay technique capable of detecting and identifying a number of species of microorganisms in a single analysis is described. The method uses optical-resonance size discrimination of microspheres to identify antibodies to which stained microorganisms are bound.

Whitten, W.B.; Shapiro, M.J.; Ramsey, J.M. [Chemical and Analytical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6142 (United States); Bronk, B.V. [United States Army Edgewood Research, Development and Engineering Center, Edgewood, Maryland 21010 (United States)

1995-06-20

277

Fluorescence decay processes following resonant 2p photoexcitation of Ar atoms and clusters studied using a time-resolved fluorescence and photoion coincidence technique  

NASA Astrophysics Data System (ADS)

The novel spectroscopic technique of time-resolved fluorescence-photoion coincidence spectroscopy (TFPICO) has been applied to the investigation of the decay processes of 2p inner-shell excited Ar atoms and clusters. For the Ar atom, only that fluorescence accompanying the production of Ar+ showed a strong dependence on excitation energy. This dependence is discussed in terms of competing Auger decay processes. For Ar clusters, the TFPICO spectra for dimer ions (Ar2)+ revealed long-lifetime fluorescence components which can be attributed to the ‘third excimer continuum’. With this work we demonstrate the usefulness of this technique for investigating the decay processes of inner-shell excited atoms and clusters.

Gejo, T.; Ikegami, T.; Honma, K.; Harries, J. R.; Tamenori, Y.

2013-04-01

278

Clinical magnetic resonance imaging  

SciTech Connect

This book presents clinical applications of magnetic resonance imaging with a strong clinical orientation. Covers technique, instrumentation, and contrast agents. Describes MRI of the neck, brain, heart, spine, TMJ and orbit, chest abdomen, pelvis, and the joints. Also includes a high field atlas of the central nervous system.

Brady, T.J.; Edelman, R.R.

1988-01-01

279

New techniques for cartilage magnetic resonance imaging relaxation time analysis: texture analysis of flattened cartilage and localized intra- and inter-subject comparisons.  

PubMed

MR relaxation time measurements of knee cartilage have shown potential to characterize knee osteoarthritis (OA). In this work, techniques that allow localized intra- and inter-subject comparisons of cartilage relaxation times, as well as cartilage flattening for texture analysis parallel and perpendicular to the natural cartilage layers, are presented. The localized comparisons are based on the registration of bone structures and the assignment of relaxation time feature vectors to each point in the bone-cartilage interface. Cartilage flattening was accomplished with Bezier splines and warping, and texture analysis was performed with second-order texture measures using gray-level co-occurrence matrices (GLCM). In a cohort of five normal subjects the performance and reproducibility of the techniques were evaluated using T1rho maps of femoral knee cartilage. The feasibility of creating a mean cartilage relaxation time map is also presented. Successful localized intra- and inter-subject T1rho comparisons were obtained with reproducibility similar to that reported in the literature for regional T2. Improvement of the reproducibility of GLCM features was obtained by flattening the T1rho maps. The results indicate that the presented techniques have potential in longitudinal and population studies of knee OA at different stages of the disease. PMID:18506807

Carballido-Gamio, Julio; Link, Thomas M; Majumdar, Sharmila

2008-06-01

280

New Techniques for Cartilage Magnetic Resonance Imaging Relaxation Time Analysis: Texture Analysis of Flattened Cartilage and Localized Intra- and Inter-subject Comparisons  

PubMed Central

MR relaxation time measurements of knee cartilage have shown potential to characterize knee osteoarthritis (OA). In this work, techniques that allow localized intra- and inter-subject comparisons of cartilage relaxation times, as well as cartilage flattening for texture analysis parallel and perpendicular to the natural cartilage layers, are presented. The localized comparisons are based on the registration of bone structures and the assignment of relaxation time feature vectors to each point in the bone– cartilage interface. Cartilage flattening was accomplished with Bezier splines and warping, and texture analysis was performed with second-order texture measures using gray-level co-occurrence matrices (GLCM). In a cohort of five normal subjects the performance and reproducibility of the techniques were evaluated using T1? maps of femoral knee cartilage. The feasibility of creating a mean cartilage relaxation time map is also presented. Successful localized intra- and inter-subject T1? comparisons were obtained with reproducibility similar to that reported in the literature for regional T2. Improvement of the reproducibility of GLCM features was obtained by flattening the T1? maps. The results indicate that the presented techniques have potential in longitudinal and population studies of knee OA at different stages of the disease. PMID:18506807

Carballido-Gamio, Julio; Link, Thomas M.; Majumdar, Sharmila

2010-01-01

281

Systematic evaluation of magnetic resonance imaging and spectroscopy techniques for imaging a transgenic model of Alzheimer's disease (A?PP/PS1).  

PubMed

Murine models of Alzheimer's disease (AD) provide means to detect and follow biomarker changes similar to those observed in humans. Non-invasive biomarkers, such as those provided by magnetic resonance imaging (MRI) and spectroscopy (MRS) methods are highly desirable, however, systematic studies of in vivo MRI/MRS methods to characterize the cerebral morphology and metabolic pattern of these mice remain scarce. We investigated sixteen consecutive slices from the brain of wild-type and A?PP/PS1 mice, obtaining a collection of T2 weighted, diffusion weighted and magnetization transfer weighted images as well as 1H PRESS spectra from the cortical and subcortical areas. Compared to controls, A?PP/PS1 mice show significant regional hyperintensities in T2 weighted images of the cerebral cortex, significant ventricular enlargement, and decreased hippocampal area and fractional magnetization transfer. MRS demonstrated an increase in the ratio of choline (Cho) to creatine (Cr) in the cortical and subcortical areas of the transgenic animals. A logistic regression classifier was implemented considering all parameters investigated, and revealed the most characteristic changes and allowed for the correct classification of control and A?PP/PS1 mice. In summary, the present results provide a useful frame to evaluate optimal MRI/MRS biomarkers for the characterization of AD models, potentially applicable in drug discovery processes, because of their non-invasive and repeatable nature in longitudinal studies. PMID:22406445

Esteras, Noemí; Alquézar, Carolina; Bartolomé, Fernando; Antequera, Desiree; Barrios, Laura; Carro, Eva; Cerdán, Sebastián; Martín-Requero, Angeles

2012-01-01

282

Effect of tunnel placements on clinical and magnetic resonance imaging findings 2 years after anterior cruciate ligament reconstruction using the double-bundle technique  

PubMed Central

Purpose The purpose of the study reported here was to find out if the clinical and magnetic resonance imaging (MRI) findings of a reconstructed anterior cruciate ligament (ACL) have an association. Our hypothesis, which was based on the different functions of the ACL bundles, was that the visibility of the anteromedial graft would have an impact on anteroposterior stability, and the visibility of the posterolateral graft on rotational stability of the knee. Methods This study is a level II, prospective clinical and MRI study (NCT02000258). The study involved 75 patients. One experienced orthopedic surgeon performed all double-bundle ACL reconstructions. Two independent examiners made the clinical examinations at 2-year follow-up: clinical examination of the knee; KT-1000, International Knee Documentation Committee and Lysholm knee evaluation scores; and International Knee Documentation Committee functional score. The MRI evaluations were made by two musculoskeletal radiologists separately, and the means of these measurements were used. Results We found that the location of the graft in the tibia had an impact on the MRI visibility of the graft at 2-year follow-up. There were significantly more partially or totally invisible grafts if the insertion of the graft was more anterior in the tibia. No association was found between the clinical results and the graft locations. Conclusion Anterior graft location in the tibia can cause graft invisibility in the MRI 2 years after ACL reconstruction, but this has no effect on the clinical recovery of the patient. PMID:25249760

Suomalainen, Piia; Kiekara, Tommi; Moisala, Anna-Stina; Paakkala, Antti; Kannus, Pekka; Järvelä, Timo

2014-01-01

283

A gas-jet transport and catcher technique for on-line production of radioactive ion beams using an electron cyclotron resonance ion-source.  

PubMed

Radioactive ion beams (RIB) have been produced on-line, using a gas-jet recoil transport coupled Electron Cyclotron Resonance (ECR) ion-source at the VECC-RIB facility. Radioactive atoms?molecules carried through the gas-jet were stopped in a catcher placed inside the ECR plasma chamber. A skimmer has been used to remove bulk of the carrier gas at the ECR entrance. The diffusion of atoms?molecules through the catcher has been verified off-line using stable isotopes and on-line through transmission of radioactive reaction products. Beams of (14)O (71 s), (42)K (12.4 h), (43)K (22.2 h), and (41)Ar (1.8 h) have been produced by bombarding nitrogen and argon gas targets with proton and alpha particle beams from the K130 cyclotron at VECC. Typical measured intensity of RIB at the separator focal plane is found to be a few times 10(3) particles per second (pps). About 3.2 × 10(3) pps of 1.4 MeV (14)O RIB has been measured after acceleration through a radiofrequency quadrupole linac. The details of the gas-jet coupled ECR ion-source and RIB production experiments are presented along with the plans for the future. PMID:23556809

Naik, V; Chakrabarti, A; Bhattacharjee, M; Karmakar, P; Bandyopadhyay, A; Bhattacharjee, S; Dechoudhury, S; Mondal, M; Pandey, H K; Lavanyakumar, D; Mandi, T K; Dutta, D P; Kundu Roy, T; Bhowmick, D; Sanyal, D; Srivastava, S C L; Ray, A; Ali, Md S

2013-03-01

284

A gas-jet transport and catcher technique for on-line production of radioactive ion beams using an electron cyclotron resonance ion-source  

SciTech Connect

Radioactive ion beams (RIB) have been produced on-line, using a gas-jet recoil transport coupled Electron Cyclotron Resonance (ECR) ion-source at the VECC-RIB facility. Radioactive atoms/molecules carried through the gas-jet were stopped in a catcher placed inside the ECR plasma chamber. A skimmer has been used to remove bulk of the carrier gas at the ECR entrance. The diffusion of atoms/molecules through the catcher has been verified off-line using stable isotopes and on-line through transmission of radioactive reaction products. Beams of {sup 14}O (71 s), {sup 42}K (12.4 h), {sup 43}K (22.2 h), and {sup 41}Ar (1.8 h) have been produced by bombarding nitrogen and argon gas targets with proton and alpha particle beams from the K130 cyclotron at VECC. Typical measured intensity of RIB at the separator focal plane is found to be a few times 10{sup 3} particles per second (pps). About 3.2 Multiplication-Sign 10{sup 3} pps of 1.4 MeV {sup 14}O RIB has been measured after acceleration through a radiofrequency quadrupole linac. The details of the gas-jet coupled ECR ion-source and RIB production experiments are presented along with the plans for the future.

Naik, V.; Chakrabarti, A.; Bhattacharjee, M.; Karmakar, P.; Bandyopadhyay, A.; Dechoudhury, S.; Mondal, M.; Pandey, H. K.; Lavanyakumar, D.; Mandi, T. K.; Dutta, D. P.; Kundu Roy, T.; Bhowmick, D.; Sanyal, D.; Srivastava, S. C. L.; Ray, A.; Ali, Md. S. [Variable Energy Cyclotron Centre (VECC), Sector-1, Block-AF, Bidhan Nagar, Kolkata 700064 (India); Bhattacharjee, S. [UGC-DAE CSR, Kolkata Centre, III/LB-8, Bidhan Nagar, Kolkata 700098 (India)

2013-03-15

285

SPECTRAL IMAGING TECHNIQUES FOR GRAIN  

Technology Transfer Automated Retrieval System (TEKTRAN)

Three spectral imaging techniques were employed for the purpose of assessing the quality of cereal grains. Each of these techniques provided unique, yet complementary, information. Nuclear magnetic resonance (NMR), also called magnetic resonance imaging (MRI), was used to detect mobile components ...

286

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

287

Mechanical characterization of articular cartilage by combining magnetic resonance imaging and finite-element analysis—a potential functional imaging technique  

NASA Astrophysics Data System (ADS)

Magnetic resonance imaging (MRI) provides a method for non-invasive characterization of cartilage composition and structure. We aimed to see whether T1 and T2 relaxation times are related to proteoglycan (PG) and collagen-specific mechanical properties of articular cartilage. Specifically, we analyzed whether variations in the depthwise collagen orientation, as assessed by the laminae obtained from T2 profiles, affect the mechanical characteristics of cartilage. After MRI and unconfined compression tests of human and bovine patellar cartilage samples, fibril-reinforced poroviscoelastic finite-element models (FEM), with depthwise collagen orientations implemented from quantitative T2 maps (3 laminae for human, 3-7 laminae for bovine), were constructed to analyze the non-fibrillar matrix modulus (PG specific), fibril modulus (collagen specific) and permeability of the samples. In bovine cartilage, the non-fibrillar matrix modulus (R = -0.64, p < 0.05) as well as the initial permeability (R = 0.70, p < 0.05) correlated with T1. In bovine cartilage, T2 correlated positively with the initial fibril modulus (R = 0.62, p = 0.05). In human cartilage, the initial fibril modulus correlated negatively (R = -0.61, p < 0.05) with T2. Based on the simulations, cartilage with a complex collagen architecture (5 or 7 laminae), leading to high bulk T2 due to magic angle effects, provided higher compressive stiffness than tissue with a simple collagen architecture (3 laminae). Our results suggest that T1 reflects PG-specific mechanical properties of cartilage. High T2 is characteristic to soft cartilage with a classical collagen architecture. Contradictorily, high bulk T2 can also be found in stiff cartilage with a multilaminar collagen fibril network. By emerging MRI and FEM, the present study establishes a step toward functional imaging of articular cartilage.

Julkunen, P.; Korhonen, R. K.; Nissi, M. J.; Jurvelin, J. S.

2008-05-01

288

On the performance of Spin Diffusion NMR Techniques in Oriented Solids: Prospects for Resonance Assignments and Distance Measurements from Separated Local Field Experiments  

PubMed Central

NMR spin diffusion experiments have the potential to provide both resonance assignment and internuclear distances for protein structure determination in oriented solid-state NMR. In this paper, we compared the efficiencies of three common spin diffusion experiments: proton-driven spin diffusion (PDSD), cross-relaxation driven spin diffusion (CRDSD), and proton-mediated proton transfer (PMPT). As model systems for oriented proteins, we used single crystals of N-acetyl-L-15N-leucine (NAL) and N-acetyl-L-15N-valyl-L-15N-leucine (NAVL) to probe long- and short distances, respectively. We demonstrate that for short 15N/15N distances such as those found in NAVL (3.3 Å), the PDSD mechanism gives the most intense cross-peaks, while for longer distances (> 6.5 Å), the CRDSD and PMPT experiments are more efficient. The PDSD was highly inefficient for transferring magnetization across distances greater than 6.5 Å (NAL crystal sample), due to small 15N/15N dipolar couplings (< 4.5 Hz). Interestingly, the mismatched Hartmann-Hahn condition present in the PMPT experiment gave more intense cross-peaks for lower 1H and 15N spinlock field strengths (32 and 17 kHz, respectively) rather than higher values (55 and 50 kHz), suggesting a more complex magnetization transfer mechanism. Numerical simulations are in good agreement with the experimental findings, suggesting a combined PMPT and CRDSD effect. We conclude that in order to assign SLF spectra and measure short and long-range distances, the combined use of homonuclear correlation spectra, such as the ones surveyed in this work, are necessary. PMID:20936833

Traaseth, Nathaniel J.; Gopinath, T.; Veglia, Gianluigi

2010-01-01

289

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

290

Resonance scraping  

SciTech Connect

Protons lost in a ring leave at a few preferred locations, determined by some non-linear property of the dipoles. This paper suggests taking control of lost protons by beating the magnets at their own game - by means of a designed resonance used as a beam scraper. It is a study of suitable resonances, including estimates of the required multipole element strengths. The appropriate resonances are two-dimensional. A large number of figures is included.

Collins, T.

1986-06-01

291

Two-frequency heating technique at the 18 GHz electron cyclotron resonance ion source of the National Institute of Radiological Sciences  

E-print Network

The two-frequency heating technique was studied to increase the beam intensities of highly charged ions provided by the high-voltage extraction configuration (HEC) ion source at the National Institute of Radiological Sciences (NIRS). The observed dependences on microwave power and frequency suggested that this technique improved plasma stability but it required precise frequency tuning and more microwave power than was available before 2013. Recently, a new, high-power (1200 W) wide bandwidth (17.1-18.5 GHz) travelling-wave-tube amplifier (TWTA) was installed. After some single tests with klystron and TWT amplifiers the simultaneous injection of the two microwaves has been successfully realized. The dependence of highly charged ions (HCI) currents on the superposed microwave power was studied by changing only the output power of one of the two amplifiers, alternatively. While operating the klystron on its fixed 18.0 GHz, the frequency of the TWTA was swept within its full limits (17.1-18.5 GHz), and the effec...

Biri, S; Muramatsu, M; Drentje, A G; Rácz, R; Yano, K; Kato, Y; Sasaki, N; Takasugi, W

2015-01-01

292

Two-frequency heating technique at the 18 GHz electron cyclotron resonance ion source of the National Institute of Radiological Sciences  

SciTech Connect

The two-frequency heating technique was studied to increase the beam intensities of highly charged ions provided by the high-voltage extraction configuration (HEC) ion source at the National Institute of Radiological Sciences (NIRS). The observed dependences on microwave power and frequency suggested that this technique improved plasma stability but it required precise frequency tuning and more microwave power than was available before 2013. Recently, a new, high-power (1200 W) wide band-width (17.1–18.5 GHz) travelling-wave-tube amplifier (TWTA) was installed. After some single tests with klystron and TWT amplifiers the simultaneous injection of the two microwaves has been successfully realized. The dependence of highly charged ions (HCI) currents on the superposed microwave power was studied by changing only the output power of one of the two amplifiers, alternatively. While operating the klystron on its fixed 18.0 GHz, the frequency of the TWTA was swept within its full limits (17.1–18.5 GHz), and the effect of this frequency on the HCI-production rate was examined under several operation conditions. As an overall result, new beam records of highly charged argon, krypton, and xenon beams were obtained at the NIRS-HEC ion source by this high-power two-frequency operation mode.

Biri, S., E-mail: biri@atomki.hu [National Institute of Radiological Science (NIRS), 4-9-1 Anagawa, Inage, Chiba 263-8555 (Japan); Institute for Nuclear Research (ATOMKI), H-4026 Debrecen, Bem tér 18/c (Hungary); Kitagawa, A.; Muramatsu, M.; Drentje, A. G. [National Institute of Radiological Science (NIRS), 4-9-1 Anagawa, Inage, Chiba 263-8555 (Japan)] [National Institute of Radiological Science (NIRS), 4-9-1 Anagawa, Inage, Chiba 263-8555 (Japan); Rácz, R. [Institute for Nuclear Research (ATOMKI), H-4026 Debrecen, Bem tér 18/c (Hungary)] [Institute for Nuclear Research (ATOMKI), H-4026 Debrecen, Bem tér 18/c (Hungary); Yano, K.; Kato, Y. [Graduated School of Engineering, Osaka University, 2-1 Yamada-oka, Suita-shi, Osaka 565-0871 (Japan)] [Graduated School of Engineering, Osaka University, 2-1 Yamada-oka, Suita-shi, Osaka 565-0871 (Japan); Sasaki, N.; Takasugi, W. [Accelerator Engineering Corporation (AEC), Inage, Chiba 263-0043 (Japan)] [Accelerator Engineering Corporation (AEC), Inage, Chiba 263-0043 (Japan)

2014-02-15

293

Two-frequency heating technique at the 18 GHz electron cyclotron resonance ion source of the National Institute of Radiological Sciences  

NASA Astrophysics Data System (ADS)

The two-frequency heating technique was studied to increase the beam intensities of highly charged ions provided by the high-voltage extraction configuration (HEC) ion source at the National Institute of Radiological Sciences (NIRS). The observed dependences on microwave power and frequency suggested that this technique improved plasma stability but it required precise frequency tuning and more microwave power than was available before 2013. Recently, a new, high-power (1200 W) wide band-width (17.1-18.5 GHz) travelling-wave-tube amplifier (TWTA) was installed. After some single tests with klystron and TWT amplifiers the simultaneous injection of the two microwaves has been successfully realized. The dependence of highly charged ions (HCI) currents on the superposed microwave power was studied by changing only the output power of one of the two amplifiers, alternatively. While operating the klystron on its fixed 18.0 GHz, the frequency of the TWTA was swept within its full limits (17.1-18.5 GHz), and the effect of this frequency on the HCI-production rate was examined under several operation conditions. As an overall result, new beam records of highly charged argon, krypton, and xenon beams were obtained at the NIRS-HEC ion source by this high-power two-frequency operation mode.

Biri, S.; Kitagawa, A.; Muramatsu, M.; Drentje, A. G.; Rácz, R.; Yano, K.; Kato, Y.; Sasaki, N.; Takasugi, W.

2014-02-01

294

Two-frequency heating technique at the 18 GHz electron cyclotron resonance ion source of the National Institute of Radiological Sciences.  

PubMed

The two-frequency heating technique was studied to increase the beam intensities of highly charged ions provided by the high-voltage extraction configuration (HEC) ion source at the National Institute of Radiological Sciences (NIRS). The observed dependences on microwave power and frequency suggested that this technique improved plasma stability but it required precise frequency tuning and more microwave power than was available before 2013. Recently, a new, high-power (1200 W) wide band-width (17.1-18.5 GHz) travelling-wave-tube amplifier (TWTA) was installed. After some single tests with klystron and TWT amplifiers the simultaneous injection of the two microwaves has been successfully realized. The dependence of highly charged ions (HCI) currents on the superposed microwave power was studied by changing only the output power of one of the two amplifiers, alternatively. While operating the klystron on its fixed 18.0 GHz, the frequency of the TWTA was swept within its full limits (17.1-18.5 GHz), and the effect of this frequency on the HCI-production rate was examined under several operation conditions. As an overall result, new beam records of highly charged argon, krypton, and xenon beams were obtained at the NIRS-HEC ion source by this high-power two-frequency operation mode. PMID:24593510

Biri, S; Kitagawa, A; Muramatsu, M; Drentje, A G; Rácz, R; Yano, K; Kato, Y; Sasaki, N; Takasugi, W

2014-02-01

295

Quality factor control for micromechanical resonators  

Microsoft Academic Search

The implementation of very high Q microelectromechanical filters, constructed of spring-coupled or parallel resonators, requires strict control over the quality factor of the constituent resonators. This report details electrostatic feedback techniques which allow precise control of the quality factor of a micromechanical resonator device, independent of the ambient operating pressure of the micromechanical system. Theoretical formulas governing Q-control are derived

C. T.-C. Nguyen; R. T. Howe

1992-01-01

296

High temperature resonant ultrasound spectroscopy methods  

Microsoft Academic Search

Resonant ultrasound spectroscopy (RUS) is a technique to obtain the full elastic tensor of single crystal materials by measuring the mechanical resonances of a polished sample. Any direct resonance measurement at high temperatures is limited by the fact that most ultrasound transducers have an upper operational limit of 200-300C. High temperature RUS measurements are made possible by separating the sample,

Guangyan Li; Gary Lamberton; Josh Gladden

2008-01-01

297

Resonant Ionization Laser Ion Source (RILIS) With Improved Selectivity Achieved By Ion Pulse Compression Using In-Source Time-of-flight Technique  

SciTech Connect

This paper describes for the first time the improved selectivity of the RILIS made possible by the time-of-flight (TOF) ion bunch compression. Brief description of the compression principles and some preliminary experimental results are presented. In the off-line experiments short ion peaks of natural Li, Na, K, Tm and Yb are observed as ions leave the RILIS-TOF structure. For Tm the ion peaks of 5 {mu}s half-height duration are detected and 1 {mu}s peaks for Sn are predicted. In view of the repetition rate of the ISOLDE-RILIS lasers it is hoped that the selectivity of Sn isotopes production may be improved as much as 100 employing the RILIS with the TOF ion bunch compression and a gating technique.

Mishin, V. I.; Malinovsky, A. L.; Mishin, D. V. [Institute for Spectroscopy Russian Academy of Sciences, 142190 Troitsk, Moscow region (Russian Federation)

2009-03-17

298

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

299

Gravitoelectromagnetic resonances  

Microsoft Academic Search

The interaction between gravitational and electromagnetic radiation has a rather long research history. It is well known, in particular, that gravity-wave distortions can drive propagating electromagnetic signals. Since forced oscillations provide the natural stage for resonances to occur, gravitoelectromagnetic resonances have been investigated as a means of more efficient gravity-wave detection methods. In this report, we consider the coupling between

Christos G. Tsagas

2011-01-01

300

Dynamic tuning of MEMS resonators via electromechanical feedback.  

PubMed

This paper introduces an active electrical technique for dynamic tuning of MEMS resonators. The proposed technique is based on using the resonator output current to generate displacement or acceleration signals by integration or differentiation operations, respectively. The resulting signal is then scaled to generate an appropriate tuning signal. When applied to the resonator through additional signal ports, the tuning signal electrically modifies the equivalent mechanical stiffness or mass of the resonator, thereby tuning the resonance frequency in a bidirectional fashion depending on the polarity of the scaling. This tuning scheme has been applied to a piezoelectric AlN-on-Si BAW square resonator to tune its 14.2 MHz resonance frequency by 22 kHz, equivalent to 1550 ppm. The proposed tuning technique can be applied to a wide range of MEMS resonators and resonant sensors, e.g., to compensate for temperature or process-induced variations in their resonance frequencies. PMID:25585397

Norouzpour-Shirazi, Arashk; Hodjat-Shamami, Mojtaba; Tabrizian, Roozbeh; Ayazi, Farrokh

2015-01-01

301

4 Nuclear Magnetic Resonance and MRI February 26, 2008  

E-print Network

4 Nuclear Magnetic Resonance and MRI February 26, 2008 The technique of nuclear magnetic resonance at Harvard, for which they both received the 1952 Physics Nobel Prize. Magnetic resonance methods have found of Magnetic Resonance Imaging (MRI) by Paul Lauter- bur, then at SUNY Stony Brook, and Peter Mansfield

Thouless, David

302

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

303

Magnetic Resonance  

Cancer.gov

Focus Group on Magnetic Resonance Spectroscopy (MRS) in Clinical Oncology(April 1999) To explore the technical requirements for MRS and the application of hydrogen and multinuclear spectroscopy for tumor response to therapy.

304

Resonant Ultrasound Spectroscopy  

Microsoft Academic Search

Resonant Ultrasound Spectroscopy (RUS) measurements of the structural phase transition in La_ {rm 2-x}Sr_{ rm x}CuO_4 are presented. After a review of the RUS technique and the description of structural phase transitions within a Ginzburg -Landau formalism, we discuss measurements of the complete elastic moduli of La_2CuO _4 and La_{1.86} Sr_{0.14}CUO _4. Large modulus-specific softening is observed in the vicinity

John Louis Sarrao

1993-01-01

305

Whole-body imaging of adoptively transferred T cells using magnetic resonance imaging, single photon emission computed tomography and positron emission tomography techniques, with a focus on regulatory T cells  

PubMed Central

Cell-based therapies using natural or genetically modified regulatory T cells (Tregs) have shown significant promise as immune-based therapies. One of the main difficulties facing the further advancement of these therapies is that the fate and localization of adoptively transferred Tregs is largely unknown. The ability to dissect the migratory pathway of these cells in a non-invasive manner is of vital importance for the further development of in-vivo cell-based immunotherapies, as this technology allows the fate of the therapeutically administered cell to be imaged in real time. In this review we will provide an overview of the current clinical imaging techniques used to track T cells and Tregs in vivo, including magnetic resonance imaging (MRI) and positron emission tomography (PET)/single photon emission computed tomography (SPECT). In addition, we will discuss how the finding of these studies can be used, in the context of transplantation, to define the most appropriate Treg subset required for cellular therapy. PMID:23574314

Leech, J M; Sharif-Paghaleh, E; Maher, J; Livieratos, L; Lechler, R I; Mullen, G E; Lombardi, G; Smyth, L A

2013-01-01

306

Characterization of sodium transport in Acholeplasma laidlawii B cells and in lipid vesicles containing purified A. laidlawii (Na+-Mg2+)-ATPase by using nuclear magnetic resonance spectroscopy and 22Na tracer techniques.  

PubMed Central

The active transport of sodium ions in live Acholeplasma laidlawii B cells and in lipid vesicles containing the (Na+-Mg2+)-ATPase from the plasma membrane of this microorganism was studied by 23Na nuclear magnetic resonance spectroscopic and 22Na tracer techniques, respectively. In live A. laidlawii B cells, the transport of sodium was an active process in which metabolic energy was harnessed for the extrusion of sodium ions against a concentration gradient. The process was inhibited by low temperatures and by the formation of gel state lipid in the plasma membrane of this organism. In reconstituted proteoliposomes containing the purified (Na+-Mg2+)-ATPase, the hydrolysis of ATP was accompanied by the transport of sodium ions into the lipid vesicles, and the transport process was impaired by reagents known to inhibit ATPase activity. At the normal growth temperature (37 degrees C), this transport process required a maximum of 1 mol of ATP per mol of sodium ion transported. Together, these results provide direct experimental evidence that the (Na+-Mg2+)-ATPase of the Acholeplasma laidlawii B membrane is the cation pump which maintains the low levels of intracellular sodium characteristic of this microorganism. PMID:2973459

Mahajan, S; Lewis, R N; George, R; Sykes, B D; McElhaney, R N

1988-01-01

307

NQR investigation of pressure-induced charge transfer in oxygen-deficient YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} ({delta} = 0.38)  

SciTech Connect

Measurements of the pressure dependence of {sup 63}Cu nuclear quadrupole frequency in YBa{sub 2}Cu{sub 3}O{sub 6.62} from ambient pressure up to 1.5 GPa at 4k have been performed. {Tc} was found to increase with pressure: d{Tc}/dp {approximately} 5 K/GPa. All observed NQR lines are linear in pressure: dln{nu}{sub Q}/dp=z. We found positive z for the empty chain sites, consistent with ionic (Cu{sup 1+}) configuration in which the atom simply feels a squeezing lattice. Planar coppers close to the empty chains have positive z, while those that are close to full chains have z {approximately} 0. We present an analysis of the NQR result on the basis of the charge transfer model in which the mobile charges migrate from the chain to the plane sites. We deduced that a transfer of 0.021 holes to the O(2,3) sites would explain the result in YBa{sub 2}Cu{sub 3}O{sub 6.62}, whereas only 0.007 holes transfer in fully oxygenated YBa{sub 2}Cu{sub 3}O{sub 7}.

Reyes, A.P.; Ahrens, E.T.; Hammel, P.C.; Heffner, R.H. [Los Alamos National Lab., NM (United States); Takigawa, M. [International Business Machines Corp., Yorktown Heights, NY (United States). Thomas J. Watson Research Center

1992-03-01

308

Nuclear magnetic resonance contrast agents  

DOEpatents

A family of contrast agents for use in magnetic resonance imaging and a method of enhancing the contrast of magnetic resonance images of an object by incorporating a contrast agent of this invention into the object prior to forming the images or during formation of the images. A contrast agent of this invention is a paramagnetic lanthanide hexaazamacrocyclic molecule, where a basic example has the formula LnC.sub.16 H.sub.14 N.sub.6. Important applications of the invention are in medical diagnosis, treatment, and research, where images of portions of a human body are formed by means of magnetic resonance techniques.

Smith, Paul H. (Los Alamos, NM); Brainard, James R. (Los Alamos, NM); Jarvinen, Gordon D. (Los Alamos, NM); Ryan, Robert R. (Los Alamos, NM)

1997-01-01

309

Nuclear magnetic resonance contrast agents  

DOEpatents

A family of contrast agents for use in magnetic resonance imaging and a method of enhancing the contrast of magnetic resonance images of an object by incorporating a contrast agent of this invention into the object prior to forming the images or during formation of the images. A contrast agent of this invention is a paramagnetic lanthanide hexaazamacrocyclic molecule, where a basic example has the formula LnC{sub 16}H{sub 14}N{sub 6}. Important applications of the invention are in medical diagnosis, treatment, and research, where images of portions of a human body are formed by means of magnetic resonance techniques. 10 figs.

Smith, P.H.; Brainard, J.R.; Jarvinen, G.D.; Ryan, R.R.

1997-12-30

310

Laser diagnostic techniques in a resonant incinerator  

NASA Astrophysics Data System (ADS)

Optical diagnostics play a key role in the development of a unique, high volumetric heat release rate incinerator design at UCLA. In the device, a derivative of an aerospace dump combustor, a pre-mixed flame is stabilized within a rectangular duct by a sudden expansion in cross section at the dump plane. Wastes injected into hot, oxidative recirculation regions downstream of the dump plane experience much larger residence times than those of the bulk flow. Particle Image Velocimetry is used to study the velocity field in the combustion cavity. The results confirm the existence of the recirculation regions and illustrate the effect of waste injection on them. Planar Laser-Induced Fluorescence of the OH radical illustrates the propagation of a vortical reaction zone (flame) into the combustion cavity and its interaction with the recirculation zones.

Cadou, Christopher P.; Logan, Pamela; Karagozian, Ann; Marchant, Roy; Smith, Owen I.

1991-04-01

311

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

312

Resonance conditions  

E-print Network

Non-linear parametric resonances occur frequently in nature. Here we summarize how they can be studied by means of perturbative methods. We show in particular how resonances can affect the motion of a test particle orbiting in the vicinity of a compact object. These mathematical toy-models find application in explaining the structure of the observed kHz Quasi-Periodic Oscillations: we discuss which aspects of the reality naturally enter in the theory, and which one still remain a puzzle.

P. Rebusco

2005-10-14

313

Resonance production  

NASA Astrophysics Data System (ADS)

Recent results on rgr(770)0, K(892)*0, f0(980), phgr(1020), Dgr(1232)++ and Lgr(1520) production in A+A and p+p collisions at SPS and RHIC energies are presented. These resonances are measured via their hadronic decay channels and used as a sensitive tool to examine the collision dynamics in the hadronic medium through their decay and regeneration. The modification of resonance mass, width and shape due to phase space and dynamical effects are discussed.

Fachini, Patricia

2004-08-01

314

Microscopic magnetic nature of water absorbed Na0.35CoO2 investigated by NMR, NQR and ?+SR  

NASA Astrophysics Data System (ADS)

In order to clarify the variation of the microscopic magnetic nature with the carrier density in NaxCoO2·yHO, we have measured positive muon-spin rotation/relaxation (?+SR) spectra for H2O as well as D2O absorbed samples. Based on the zero field (ZF-) ?+SR measurements, there was no clear difference between the two superconducting phases (SC-I and SC-II). Furthermore, the ZF-spectrum for the H2O absorbed sample exhibits a clear oscillation in the whole T range measured (1.4-100 K), suggesting the formation of “[H3O]+-like” H2?+O ions in the sample. Further, the absence of an oscillation in the D2O absorbed sample also evidences the presence of H2?+O. We also measured 59Co nuclear quadrupole resonance spectra of magnetic sample. The temperature dependence of spectra shows that there is no evidence of charge ordering and CDW ordering around magnetic transition temperature.

Ohta, Hiroto; Månsson, Martin; Ikedo, Yutaka; Sugiyama, Jun; Michioka, Chishiro; Yoshimura, Kazuyoshi; Brewer, Jess H.; Ansaldo, Eduardo J.; Stubbs, Scott L.; Chow, Kim H.; Lord, James S.

2010-12-01

315

Autostereogram resonators  

NASA Astrophysics Data System (ADS)

Autostereograms, or "Magic Eye" pictures, are repeating patterns designed to give the illusion of depth. Here we discuss optical resonators that create light patterns which, when viewed from a suitable position by a monocular observer, are autostereograms of the three-dimensional shape of one of the mirror surfaces.

Leavey, Sean; Rae, Katherine; Murray, Adam; Courtial, Johannes

2012-09-01

316

Nonlinear resonant ultrasound spectroscopy (NRUS) applied to damage assessment in bone  

Microsoft Academic Search

Nonlinear resonant ultrasound spectroscopy (NRUS) is a resonance-based technique exploiting the significant nonlinear behavior of damaged materials. In NRUS, the resonant frequency(ies) of an object is studied as a function of the excitation level. As the excitation level increases, the elastic nonlinearity is manifest by a shift in the resonance frequency. This study shows the feasibility of this technique for

Marie Muller; Alexander Sutin; Robert Guyer; Maryline Talmant; Pascal Laugier; Paul A. Johnson

2005-01-01

317

Evaluation of the Chromium Resonance Parameters Including Resonance Parameter Covariance  

SciTech Connect

The intent of this work is to report the results and describe the procedures utilized to evaluate the chromium isotopes' cross sections, i.e., (50)Cr, (52)Cr, (53)Cr, and (54)Cr, for criticality safety applications. The evaluations were done in the resolved resonance region using the reduced Reich-Moore R-matrix formalism. The novel aspect of this evaluation is the inclusion of new transmission and capture cross-section measurements performed at the Oak Ridge Electron Linear Accelerator (ORELA) for energies below 100 keV and the extension of the (53)Cr energy region. The resonance analysis was performed with the multilevel R-matrix code, SAMMY, which utilizes the generalized least-squares technique based on the Bayes' theory. Complete sets of resonance parameters and resonance parameter covariance matrices (RPCMs) were obtained for each of the chromium isotopes from the SAMMY analysis of the experimental database.

Leal, Luiz C [ORNL; Derrien, Herve [ORNL; Guber, Klaus H [ORNL; Arbanas, Goran [ORNL; Wiarda, Dorothea [ORNL

2011-01-01

318

Microwave and millimeter-wave high-Q micromachined resonators  

Microsoft Academic Search

Alternative techniques for integrating high quality factor res- onators using micromachining techniques have been investigated. Two methods are presented which include suspending microstrip lines thin di- electric membranes resulting in an effective dielectric constant of near unity, and integrating three-dimensional micromachined waveguide cavity resonators with planar feedlines. These resonators show large improve- ments in quality factor over conventional techniques, and

Andrew R. Brown; Pierre Blondy; Gabriel M. Rebeiz

1999-01-01

319

Acoustic resonance spectroscopy in nuclear safeguards  

SciTech Connect

Objects resonate at specific frequencies when mechanically excited. The specific resonance frequencies are a function of shape, size, material of construction, and contents of the object. This paper discusses the use of acoustic resonance spectroscopy (ARS) to monitor containers and detect tampering. Evaluation of this technique is based on simulated storage simulations. Although these simulations show promise for this application of ARS, final evaluation will require actual field testing.

Olinger, C.T.; Lyon, M.J.; Stanbro, W.D.; Mullen, M.F.; Sinha, D.N.

1993-08-01

320

Optical Microspherical Resonators for Biomedical Sensing  

PubMed Central

Optical resonators play an ubiquitous role in modern optics. A particular class of optical resonators is constituted by spherical dielectric structures, where optical rays are total internal reflected. Due to minimal reflection losses and to potentially very low material absorption, these guided modes, known as whispering gallery modes, can confer the resonator an exceptionally high quality factor Q, leading to high energy density, narrow resonant-wavelength lines and a lengthy cavity ringdown. These attractive characteristics make these miniaturized optical resonators especially suited as laser cavities and resonant filters, but also as very sensitive sensors. First, a brief analysis is presented of the characteristics of microspherical resonators, of their fabrication methods, and of the light coupling techniques. Then, we attempt to overview some of the recent advances in the development of microspherical biosensors, underlining a number of important applications in the biomedical field. PMID:22346603

Soria, Silvia; Berneschi, Simone; Brenci, Massimo; Cosi, Franco; Conti, Gualtiero Nunzi; Pelli, Stefano; Righini, Giancarlo C.

2011-01-01

321

Frequency stabilization of the non resonant wave of a continuous-wave singly resonant optical parametric oscillator  

E-print Network

We present an experimental technique allowing to stabilize the frequency of the non resonant wave in a singly resonant optical parametric oscillator (SRO) down to the kHz level, much below the pump frequency noise level. By comparing the frequency of the non resonant wave with a reference cavity, the pump frequency noise is imposed to the frequency of the resonant wave, and is thus subtracted from the frequency of the non resonant wave. This permits the non resonant wave obtained from such a SRO to be simultaneously powerful and frequency stable, which is usually impossible to obtain when the resonant wave frequency is stabilized.

Ly, Aliou; Bretenaker, Fabien

2015-01-01

322

Gravitoelectromagnetic resonances  

NASA Astrophysics Data System (ADS)

The interaction between gravitational and electromagnetic radiation has a rather long research history. It is well known, in particular, that gravity-wave distortions can drive propagating electromagnetic signals. Since forced oscillations provide the natural stage for resonances to occur, gravitoelectromagnetic resonances have been investigated as a means of more efficient gravity-wave detection methods. In this report, we consider the coupling between the Weyl and the Maxwell fields on a Minkowski background, which also applies to astrophysical environments where gravity is weak, at the second perturbative level. We use covariant methods that describe gravitational waves via the transverse component of the shear, instead of pure-tensor metric perturbations. The aim is to calculate the properties of the electromagnetic signal, which emerges from the interaction of its linear counterpart with an incoming gravitational wave. Our analysis shows how the wavelength and the amplitude of the gravitationally driven electromagnetic wave vary with the initial conditions. More specifically, for certain initial data, the amplitude of the induced electromagnetic signal is found to diverge. Analogous, diverging, gravitoelectromagnetic resonances were also reported in cosmology. Given that, we extend our Minkowski space study to cosmology and discuss analogies and differences in the physics and in the phenomenology of the Weyl-Maxwell coupling between the aforementioned two physical environments.

Tsagas, Christos G.

2011-08-01

323

Integral resonant control of collocated smart structures  

Microsoft Academic Search

This paper introduces integral resonant control, IRC, a simple, robust and well-performing technique for vibration control in smart structures with collocated sensors and actuators. By adding a direct feed-through to a collocated system, the transfer function can be modified from containing resonant poles followed by interlaced zeros, to zeros followed by interlaced poles. It is shown that this modification permits

Sumeet S. Aphale; Andrew J. Fleming; S. O. Reza Moheimani

2007-01-01

324

Magnetic resonance imaging of radiation optic neuropathy  

SciTech Connect

Three patients with delayed radiation optic neuropathy after radiation therapy for parasellar neoplasms underwent magnetic resonance imaging. The affected optic nerves and chiasms showed enlargement and focal gadopentetate dimeglumine enhancement. The magnetic resonance imaging technique effectively detected and defined anterior visual pathway changes of radionecrosis and excluded the clinical possibility of visual loss because of tumor recurrence.

Zimmerman, C.F.; Schatz, N.J.; Glaser, J.S. (Univ. of Miami, FL (USA))

1990-10-15

325

Optically Detected Magnetic Resonance Imaging  

E-print Network

Optically detected magnetic resonance (ODMR) provides ultrasensitive means to detect and image a small number of electron and nuclear spins, down to the single spin level with nanoscale resolution. Despite the significant recent progress in this field, it has never been combined with the power of pulsed magnetic resonance imaging (MRI) techniques. Here, we demonstrate for the first time how these two methodologies can be integrated using short pulsed magnetic field gradients to spatially-encode the sample. This results in what we denote as an "optically detected magnetic resonance imaging" (ODMRI) technique. It offers the advantage that the image is acquired in parallel from all parts of the sample, with well-defined three-dimensional point-spread function, and without any loss of spectroscopic information. In addition, this approach may be used in the future for parallel but yet spatially-selective efficient addressing and manipulation of the spins in the sample. Such capabilities are of fundamental importan...

Blank, Aharon; Fischer, Ran; London, Paz; Gershoni, David

2014-01-01

326

Optically detected magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

Optically detected magnetic resonance provides ultrasensitive means to detect and image a small number of electron and nuclear spins, down to the single spin level with nanoscale resolution. Despite the significant recent progress in this field, it has never been combined with the power of pulsed magnetic resonance imaging techniques. Here, we demonstrate how these two methodologies can be integrated using short pulsed magnetic field gradients to spatially encode the sample. This result in what we denote as an "optically detected magnetic resonance imaging" technique. It offers the advantage that the image is acquired in parallel from all parts of the sample, with well-defined three-dimensional point-spread function, and without any loss of spectroscopic information. In addition, this approach may be used in the future for parallel but yet spatially selective efficient addressing and manipulation of the spins in the sample. Such capabilities are of fundamental importance in the field of quantum spin-based devices and sensors.

Blank, Aharon; Shapiro, Guy; Fischer, Ran; London, Paz; Gershoni, David

2015-01-01

327

Methods for chemical exchange saturation transfer magnetic resonance imaging  

E-print Network

Chemical exchange saturation transfer (CEST) is a relatively new magnetic resonance imaging (MRI) acquisition technique that generates contrast dependent on tissue microenvironment, such as protein concentration and ...

Scheidegger, Rachel Nora

2013-01-01

328

Pocket atlas of cranial magnetic resonance imaging  

SciTech Connect

This atlas illustrates normal cerebral anatomy in magnetic resonance images. From their studies in cerebral anatomy utilizing cryomicrotome and other techniques, the authors selected more than 100 high-resolution images that represent the most clinically useful scans.

Haughton, V.M.; Daniels, D.L.

1986-01-01

329

If It's Resonance, What is Resonating?  

ERIC Educational Resources Information Center

The phenomenon under the name "resonance," which, is based on the mathematical analogy between mechanical resonance and the behavior of wave functions in quantum mechanical exchange phenomena was described. The resonating system does not have a structure intermediate between those involved in the resonance, but instead a structure which is further…

Kerber, Robert C.

2006-01-01

330

Nanotube resonator devices  

DOEpatents

A fully-functional radio receiver fabricated from a single nanotube is being disclosed. Simultaneously, a single nanotube can perform the functions of all major components of a radio: antenna, tunable band-pass filter, amplifier, and demodulator. A DC voltage source, as supplied by a battery, can power the radio. Using carrier waves in the commercially relevant 40-400 MHz range and both frequency and amplitude modulation techniques, successful music and voice reception has been demonstrated. Also disclosed are a radio transmitter and a mass sensor using a nanotube resonator device.

Jensen, Kenneth J; Zettl, Alexander K; Weldon, Jeffrey A

2014-05-06

331

Improved treatment planning for the Syed-Neblett template using endorectal-coil magnetic resonance and intraoperative (laparotomy/laparoscopy) guidance: a new integrated technique for hysterectomized women with vaginal tumors.  

PubMed

The Syed template (Alpha-Omega Services, Bellflower, CA) represents an advance in interstitial gynecologic brachytherapy; however, its appeal is diminished by inaccuracies in target definition secondary to suboptimal imaging of gynecologic tumors and the risk of viscus perforation during a "blind" procedure. Magnetic resonance (MR) scanning with an endorectal coil and computed tomography were studied as a possible tool to improve target definition and maximize treatment planning with Syed templates. Abdominopelvic contents could be visualized directly through a laparotomy incision or indirectly with a laparoscopic video display to allow further target definition and minimize complications associated with blind procedures after hysterectomy. The synthesis of these techniques with Syed template applications was attempted to potentiate the utility of this brachytherapy system. Five patients with apical vaginal tumors which arose after previous hysterectomies (two endometrial cancer recurrences, one recurrent uterine sarcoma, two primary vaginal cancers) were referred for radiotherapy. In three cases, external beam pelvic radiotherapy (median dose, 45 Gy; range, 45-50.4 Gy) was delivered initially. In all cases, the Syed applicator was used for the brachytherapy component of the treatment. In two cases, high-resolution MR images (400 x 400 microns) of the vaginal apex were obtained after insertion of an endorectal surface coil. The images defined the relationships between the template, target volume, bladder, rectum, and intestine. The other three cases were planned with computerized tomography (CT). In all cases, intraoperative examination of the abdominopelvic contents was provided when laparotomy and/or laparoscopy was performed by the surgical team. The median brachytherapy dose prescribed to the isodose envelope covering the target volume was 40 Gy (range, 31-50 Gy). In all cases, the target volumes could be encompassed by the 60 cGy/hr isodose line. Tumor volume estimation was better with MR than CT. Procedure time was shorter with laparoscopy than with laparotomy. In two cases, bowel displacement was performed (one tissue expander, one omental sling) to prevent viscus perforation by interstitial needles. Four of five patients responded completely to the treatment. In three cases, local control was maintained at a median follow-up of 11 months. In conclusion, endorectal coil MRI may be advantageous to CT of the pelvis in that it allows preplanning to be achieved with greater precision and with less planning time. Major intraoperative complications (i.e., perforation of hollow viscus organs) can be avoided when the course of interstitial catheters is visualized from above by the surgical team.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:7896194

Corn, B W; Lanciano, R M; Rosenblum, N; Schnall, M; King, S; Epperson, R

1995-02-01

332

High-Resolution X-Ray Probes Using Nuclear Resonant Scattering  

Microsoft Academic Search

New experimental techniques are demonstrated that use nuclear resonance scattering and improved X-ray optics to probe atomic systems. The techniques include measuring lattice excitations via inelastic nuclear resonant scattering and measuring the distribution of magnetization in a multilayer using coherent nuclear resonant scattering. In general, the techniques developed require that the system being probed contain an isotope with a low-energy

Thomas Scott Toellner

1996-01-01

333

Theory and Applications of Surface Plasmon Resonance, Resonant Mirror, Resonant Waveguide Grating, and Dual Polarization Interferometry Biosensors  

PubMed Central

Biosensors have been used extensively in the scientific community for several purposes, most notably to determine association and dissociation kinetics, protein-ligand, protein-protein, or nucleic acid hybridization interactions. A number of different types of biosensors are available in the field, each with real or perceived benefits over the others. This review discusses the basic theory and operational arrangements of four commercially available types of optical biosensors: surface plasmon resonance, resonant mirror, resonance waveguide grating, and dual polarization interferometry. The different applications these techniques offer are discussed from experiments and results reported in recently published literature. Additionally, recent advancements or modifications to the current techniques are also discussed. PMID:22163431

Daghestani, Hikmat N.; Day, Billy W.

2010-01-01

334

Classification of prostate magnetic resonance spectra using support vector machine  

E-print Network

that nuclear magnetic resonance spectra are sensitive enough to distinguish normal and cancer. In this paperClassification of prostate magnetic resonance spectra using support vector machine S. Parfait a, we propose a classification technique of spectra from magnetic resonance spectroscopy. We studied au

335

Principles of functional Magnetic Resonance Martin A. Lindquist  

E-print Network

1 Principles of functional Magnetic Resonance Imaging Martin A. Lindquist Department of Magnetic Resonance Signal Generation ............. 6 1.2.1.1 The MRI Scanner ...................................................... 40 1.1 Introduction Functional Magnetic Resonance Imaging (fMRI) is a non-invasive technique

336

Surface plasmon resonance shows that type IV pili are  

E-print Network

REPORT Surface plasmon resonance shows that type IV pili are important in surface attachment. Here, using the surface analytical technique, surface plasmon resonance (SPR), we follow the attachment; pili; surface plasmon resonance; biofilm formation 1. INTRODUCTION Bacterial attachment is a critical

Buckling, Angus

337

Transmission surface plasmon resonance microscopy  

NASA Astrophysics Data System (ADS)

We present a microscopy technique to image minute variations of optical properties at the interface of a metallic thin-film. This technique is based on an original transmission configuration of surface plasmon resonance sensors. It combines high diffraction-limited lateral resolution with unaltered refractive index sensitivity. Transmitted light is obtained by using near-field transducers positioned at the metal/dielectric interface to probe the propagative surface plasmon dispersion curve. This label-free technique can find applications in highly multiplexed molecular sensing or full-field surface microscopy. As an example, we show tomography images of silica nanometric patterns.

Loison, Olivier; Fort, Emmanuel

2013-09-01

338

Excitation of giant resonances via direct reactions  

SciTech Connect

Experimental measurements of electric giant multipole resonances are discussed. The parameters of the giant quadrupole resonance are now firmly established by an extensive set of measurements. The GQR is providing a significant influence in other areas of nuclear physics. The monopole resonance has now been established and its observation has provided the first direct measure of the nuclear compressibility. A strong case for the existence of a giant octupole resonance is now being made through a variety of hadron reactions. However, the supply of giant multipole resonances has not been exhausted. The newer techniques such as higher energy proton scattering, charge exchange reactions, heavy-ion scattering and pion reactions offer considerable hope for identifying new resonances during the next few years.

Bertrand, F.E.

1982-01-01

339

Resonant acoustic radiation force optical coherence elastography  

NASA Astrophysics Data System (ADS)

We report on a resonant acoustic radiation force optical coherence elastography (ARF-OCE) technique that uses mechanical resonant frequency to characterize and identify tissues of different types. The linear dependency of the resonant frequency on the square root of Young's modulus was validated on silicone phantoms. Both the frequency response spectrum and the 3D imaging results from the agar phantoms with hard inclusions confirmed the feasibility of deploying the resonant frequency as a mechanical contrast for tissue imaging. Furthermore, the results of resonant ARF-OCE imaging of a post-mortem human coronary artery with atherosclerosis demonstrate the potential of the resonant ARF-OCE as a non-invasive method for imaging and characterizing vulnerable plaques.

Qi, Wenjuan; Li, Rui; Ma, Teng; Li, Jiawen; Kirk Shung, K.; Zhou, Qifa; Chen, Zhongping

2013-09-01

340

Resonant acoustic radiation force optical coherence elastography  

PubMed Central

We report on a resonant acoustic radiation force optical coherence elastography (ARF-OCE) technique that uses mechanical resonant frequency to characterize and identify tissues of different types. The linear dependency of the resonant frequency on the square root of Young's modulus was validated on silicone phantoms. Both the frequency response spectrum and the 3D imaging results from the agar phantoms with hard inclusions confirmed the feasibility of deploying the resonant frequency as a mechanical contrast for tissue imaging. Furthermore, the results of resonant ARF-OCE imaging of a post-mortem human coronary artery with atherosclerosis demonstrate the potential of the resonant ARF-OCE as a non-invasive method for imaging and characterizing vulnerable plaques. PMID:24086090

Qi, Wenjuan; Li, Rui; Ma, Teng; Li, Jiawen; Kirk Shung, K.; Zhou, Qifa; Chen, Zhongping

2013-01-01

341

THE USE OF MAGNETIC RESONANCE SPECTROSCOPY AND MAGNETIC RESONANCE IMAGING IN ALCOHOL RESEARCH  

Microsoft Academic Search

he recent emergence of magnetic resonance (MR)­ based neuroimaging techniques has dramatically improved researchers' ability to understand the neuro­ pathology of alcoholism. These techniques range from those that directly monitor the metabolism and the biochemical and physiological effects (i.e., the pharmacodynamics) of alcohol within the brain to techniques that examine the impact of heavy alcohol use on brain structure and

Bonnie J. Nagel; Christopher D. Kroenke

2008-01-01

342

Field Quantization for Chaotic Resonators with Overlapping Modes  

NASA Astrophysics Data System (ADS)

Feshbach's projector technique is employed to quantize the electromagnetic field in optical resonators with an arbitrary number of escape channels. We find spectrally overlapping resonator modes coupled due to the damping and noise inflicted by the external radiation field. For wave chaotic resonators the mode dynamics is determined by a non-Hermitean random matrix. Upon including an amplifying medium, our dynamics of open-resonator modes may serve as a starting point for a quantum theory of random lasing.

Hackenbroich, Gregor; Viviescas, Carlos; Haake, Fritz

2002-07-01

343

Quantitative analysis by resonant laser ablation with optical emission detection: Resonant laser-induced breakdown spectroscopy  

Microsoft Academic Search

Resonant laser ablation (RLA) is a solid sampling technique that makes use of radiation trapping, and desorption induced by electronic transitions (DIET), to produce enhanced numbers of analyte atoms in the laser-induced plasma (LIP). This is achieved by tuning the laser ablation wavelength to a gas-phase resonant transition of the analyte. In this paper, RLA was coupled with detection of

Danielle Cleveland; Robert G. Michel

2010-01-01

344

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

345

Resonant ultrasound spectroscopy: applications, current status and limitations  

Microsoft Academic Search

Over the last 10 years, resonant ultrasound spectroscopy (RUS) has become a versatile laboratory technique for measuring second-order elastic constants and ultrasonic attenuation in solids. The technique is based on measuring the spectrum of mechanical resonances for a sample of known shape (usually a parallelepiped). This spectrum cannot be deconvoluted to deduce the elastic constants. Instead, an approximate spectrum is

R. B Schwarz; J. F Vuorinen

2000-01-01

346

Magnetic resonance angiography  

MedlinePLUS

MRA; Angiography - magnetic resonance ... Kwong RY. Cardiovascular Magnetic Resonance Imaging. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine . ...

347

Mechanical resonance of individual nanostructures  

NASA Astrophysics Data System (ADS)

In this thesis the non-contact mode atomic force microscopy (NCM AFM) was used to measure very high frequency (VHF) mechanical resonance (MR) of individual nanostructures. The effect of coupling between the probe and sample on the measured resonant frequency, for both contact mode AFM (CM AFM) and NCM AFM, was analytically evaluated and showed the NCM AFM as superior due to the gentle interaction. The NCM AFM was experimentally validated by first demonstrating a high frequency resonant measurement of a piezo. An electrically driven piezo (with a 1 cm2 Si piece glued on top) was found to have a clear MR of ˜11.8 MHz using the NCM AFM resonant technique. We also showed that the NCM AFM technique was able to detect a 41 MHz vibration. Comparing the optically measured MR of a series of cantilevers with NCM AFM measured MR showed virtually no shift of the resonant frequency of the sample cantilevers. In addition, the sample cantilever was driven at its first harmonic frequency while the vertical displacement along its length was measured and its length dependence matched the expected 1st order mode shape. After having had experimentally validated the NCM AFM technique we went on to measure the VHF (>30 MHz) MR of individual rods and springs. These nanostructures were grown using a newly built oblique angle ebeam deposition (OAED) system. The MR of individual rods showed resonant peaks ranging from ˜30 MHz to ˜160 MHz. The MR of the rods were further confirmed by observing scanning electron microscopy (SEM) image blurring (rod vibration). Nanometer scale spring samples were grown in the OAED system. The MR of the spring samples was measured and found to lie between ˜30 and ˜300 MHz. The measured MR of both rod and spring samples were compared with theoretical values. The comparison took into account variations in sample geometry and had good agreement. This thesis work demonstrates for the first time the validity of the using the NCM AFM technique to measure the mechanical resonance frequency of individual nanostructures.

Parker, Thomas C.

348

Tunable resonator-based devices for producing variable delays and narrow spectral linewidths  

NASA Technical Reports Server (NTRS)

Devices with two or more coupled resonators to produce narrow spectral responses due to interference of signals that transmit through the resonators and techniques for operating such devices to achieve certain operating characteristics are described. The devices may be optical devices where optical resonators such as whispering gallery mode resonators may be used. In one implementation, at least one of the coupled optical resonators is a tunable resonator and is tuned to change its resonance frequency to tune the spectral response of the device. The described devices and techniques may be applied in optical filters, optical delays, optical waveform generators, and other applications.

Savchenkov, Anatoliy (Inventor); Maleki, Lutfollah (Inventor); Matsko, Andrey B. (Inventor); Ilchenko, Vladimir (Inventor)

2006-01-01

349

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

350

Diagnosis of carotid-cavernous fistulas with magnetic resonance angiography—demonstrating the draining veins utilizing 3-D time-of-flight and 3-D phase-contrast techniques  

Microsoft Academic Search

This study assessed the ability to diagnose carotid-cavernous fistulas (CCFs) non-invasively using magnetic resonance angiogrphy (MRA). Both three-dimensional time-of-flight (3-D TOF) MRA and three-dimensional phase-contrast (3-D PC) MRA were compared with conventional cerebral angiography in nine patients with CCFs. CCFs were grouped according to Barrow's classification. In all cases, 3-D TOF MRA revealed an inferior petrosal sinus as a draining

Fusao Ikawa; Tohru Uozumi; Katsuzo Kiya; Kaoru Kurisu; Kazunori Arita; Masayuki Sumida

1996-01-01

351

Triply resonant sum frequency spectroscopy: combining advantages of resonance Raman and 2D-IR.  

PubMed

This article describes the new multidimensional spectroscopy technique triply resonant sum frequency spectroscopy, a four-wave mixing technique sharing advantages of both 2D-IR and resonance Raman experiments. In this technique, lasers with three independent frequencies interact coherently within a sample and generate an output frequency at their triple summation. The output intensity depends on coupled electronic and vibrational resonances in the sample. We use an organic dye as a model system to demonstrate fully resonant, fully coherent multidimensional spectroscopy using two independently tunable mid-infrared vibrational interactions and one visible electronic interaction. When the pulses are time ordered, the method has a single coherence pathway, eliminating interference between pathways. Fundamental vibrational transitions appear on one axis and overtones and combinations bands on the other, allowing anharmonicities of the modes to be determined easily and conveying molecular coupling information. The experiments demonstrate coupling between seven vibrational ring modes and an electronic state, the resolution of a Fermi resonance, detection of low concentrations, elimination of excitation pulse scattering and fluorescence, background suppression of solvent and co-solutes, and observation of coherence dephasing dynamics. The electronic resonance enhancements used in this methodology are similar to the enhancements responsible for resonance Raman spectroscopy and can be considered resonance 2D-IR spectroscopy. PMID:24160771

Boyle, Erin S; Neff-Mallon, Nathan A; Wright, John C

2013-11-27

352

Ion cyclotron resonance cell  

DOEpatents

An ion cyclotron resonance cell is disclosed having two adjacent sections separated by a center trapping plate. The first section is defined by the center trapping plate, a first end trapping plate, and excitation and detector electrodes. The second section includes a second end trapping plate spaced apart from the center plate, a mirror, and an analyzer. The analyzer includes a wavelength-selective light detector, such as a detector incorporating an acousto-optical device (AOD) and a photodetector. One or more ion guides, grounded plates with holes for the ion beam, are positioned within the vacuum chamber of the mass spectrometer between the ion source and the cell. After ions are trapped and analyzed by ion cyclotron resonance techniques in the first section, the ions of interest are selected according to their mass and passed into the second section for optical spectroscopic studies. The trapped ions are excited by light from a laser and caused thereby to fluoresce. The fluorescent light emitted by the excited ions is reflected by the mirror and directed onto the detector. The AOD is scanned, and the photodetector output is recorded and analyzed. The ions remain in the second section for an extended period, enabling multiple studies to be carried out on the same ensemble of ions. 5 figs.

Weller, R.R.

1995-02-14

353

Ion cyclotron resonance cell  

DOEpatents

An ion cyclotron resonance cell having two adjacent sections separated by a center trapping plate. The first section is defined by the center trapping plate, a first end trapping plate, and excitation and detector electrodes. The second section includes a second end trapping plate spaced apart from the center plate, a mirror, and an analyzer. The analyzer includes a wavelength-selective light detector, such as a detector incorporating an acousto-optical device (AOD) and a photodetector. One or more ion guides, grounded plates with holes for the ion beam, are positioned within the vacuum chamber of the mass spectrometer between the ion source and the cell. After ions are trapped and analyzed by ion cyclotron resonance techniques in the first section, the ions of interest are selected according to their mass and passed into the second section for optical spectroscopic studies. The trapped ions are excited by light from a laser and caused thereby to fluoresce. The fluorescent light emitted by the excited ions is reflected by the mirror and directed onto the detector. The AOD is scanned, and the photodetector output is recorded and analyzed. The ions remain in the second section for an extended period, enabling multiple studies to be carried out on the same ensemble of ions.

Weller, Robert R. (Aiken, SC)

1995-01-01

354

Dominant resonant mode damping of a piezoelectric tube nanopositioner using optimal sensorless shunts  

E-print Network

shunts, optimized using H2 and H techniques. These shunts damp the modal amplitude of the first resonantDominant resonant mode damping of a piezoelectric tube nanopositioner using optimal sensorless the first mechanical resonance frequency. Feedback control techniques and shunt damping methods have shown

Fleming, Andrew J.

355

Nuclear Resonance Fluorescence of U-235  

SciTech Connect

Nuclear resonance fluorescence is a physical process that provides an isotopic-specific signature that could be used for the identification and characterization of materials. The technique involves the detection of prompt discrete-energy photons emitted from a sample which is exposed to photons in the MeV energy range. Potential applications of the technique range from detection of high explosives to characterization of special nuclear materials. One isotope of significant interest is 235U. Pacific Northwest National Laboratory and Passport Systems have collaborated to conduct measurements to search for a nuclear resonance fluorescence response of 235U below 3 MeV using a 200 g sample of highly enriched uranium. Nine 235U resonances between 1650 and 2010 keV were identified in the preliminary analysis. Analysis of the measurement data to determine the integrated cross sections of the resonances is in progress.

Warren, Glen A.; Caggiano, Joseph A.; Hensley, Walter K.; Lepel, Elwood A.; Pratt, Sharon L.; Bertozzi, William; Korbly, Steve; Ledoux, Robert; Park, William H.

2009-07-13

356

Thermal response of chalcogenide microsphere resonators  

SciTech Connect

A chalcogenide microsphere resonator (CMR) used for temperature sensing is proposed and demonstrated. The CMR is fabricated using a simple technique of heating chalcogenide glass and allowing the molten glass to form a microsphere on the waist of a tapered silica fibre. The thermal responses of the CMR is investigated and compared to that of a single-mode-fibre (SMF) based microsphere resonator. It is observed that the CMR sensitivity to ambient temperature changes is 8 times higher than that of the SMF-based microsphere resonator. Heating the chalcogenide microsphere with a laser beam periodically turned on and off shows periodic shifts in the transmission spectrum of the resonator. By injecting an intensity-modulated cw signal through the resonator a thermal relaxation time of 55 ms is estimated.

Ahmad, H; Aryanfar, I; Lim, K S; Chong, W Y; Harun, S W

2012-05-31

357

Low-loss coupling to dielectric resonators  

NASA Technical Reports Server (NTRS)

A compilation is presented of experimental observations and arguments concerning the use of dielectric resonators in applications requiring both tight coupling (beta greater than 10) and high unloaded Q, such as low loss bandpass filters. The microstrip coupled dielectric resonator is the primary focus, but an alternative coupling technique is discussed and comparatively evaluated. It is concluded that coupling factors as large as 65 are achievable.

Hearn, C. P.; Bradshaw, E. S.; Trew, R. J.; Hefner, B. B., Jr.

1991-01-01

358

Manual of clinical magnetic resonance imaging  

SciTech Connect

This work is a guide to conducting magnetic resonance imaging (MRI) examinations. The manual presents specific imaging protocols for various MRI examinations of the body. An introductory section describes the physical principles and techniques of magnetic resonance imaging and describes the most commonly encountered artifacts. Guidelines are offered for selecting imaging protocols and conducting examinations of the head, spine, neck, chest, cardiovascular system, abdomen, pelvis, musculoskeletal system, and breast.

Heiken, J.P.; Glazer, H.S.; Lee, J.K.T.; Murphy, W.A.; Gado, M.

1986-01-01

359

Role of bromine in restoring superconductivity in YBa2Cu3Oy  

Microsoft Academic Search

63,65Cu nuclear quadrupole resonance (NQR), 63,65Cu and 79,81Br nuclear magnetic resonance (NMR), and Br K-edge x-ray-absorption fine-structure (XAFS) measurement techniques have been used to study the local structures of Cu and Br in well-characterized samples of deoxygenated and brominated YBa2Cu3Oy (YBCO). The combined results provide a detailed picture of the role of bromine in reoxygenating the YBCO structure and an

D. M. Potrepka; J. I. Budnick; D. B. Fenner; W. A. Hines; M. Balasubramanian; A. R. Moodenbaugh

1999-01-01

360

Numerical Investigations of High Pressure Acoustic Waves in Resonators  

NASA Technical Reports Server (NTRS)

This presentation presents work on numerical investigations of nonlinear acoustic phenomena in resonators that can generate high-pressure waves using acoustic forcing of the flow. Time-accurate simulations of the flow in a closed cone resonator were performed at different oscillation frequencies and amplitudes, and the numerical results for the resonance frequency and fluid pressure increase match the GRC experimental data well. Work on cone resonator assembly simulations has started and will involve calculations of the flow through the resonator assembly with and without acoustic excitation. A new technique for direct calculation of resonance frequency of complex shaped resonators is also being investigated. Script-driven command procedures will also be developed for optimization of the resonator shape for maximum pressure increase.

Athavale, Mahesh; Pindera, Maciej; Daniels, Christopher C.; Steinetz, Bruce M.

2004-01-01

361

Approaching Moons from Resonance via Invariant Manifolds  

NASA Technical Reports Server (NTRS)

In this work, the approach phase from the final resonance of the endgame scenario in a tour design is examined within the context of invariant manifolds. Previous analyses have typically solved this problem either by using numerical techniques or by computing a catalog of suitable trajectories. The invariant manifolds of a selected set of libration orbits and unstable resonant orbits are computed here to serve as guides for desirable approach trajectories. The analysis focuses on designing an approach phase that may be tied into the final resonance in the endgame sequence while also targeting desired conditions at the moon.

Anderson, Rodney L.

2012-01-01

362

Opto-electronic oscillators having optical resonators  

NASA Technical Reports Server (NTRS)

Systems and techniques of incorporating an optical resonator in an optical part of a feedback loop in opto-electronic oscillators. This optical resonator provides a sufficiently long energy storage time and hence to produce an oscillation of a narrow linewidth and low phase noise. Certain mode matching conditions are required. For example, the mode spacing of the optical resonator is equal to one mode spacing, or a multiplicity of the mode spacing, of an opto-electronic feedback loop that receives a modulated optical signal and to produce an electrical oscillating signal.

Yao, Xiaotian Steve (Inventor); Maleki, Lutfollah (Inventor); Ilchenko, Vladimir (Inventor)

2003-01-01

363

Optically Detected Magnetic Resonance (ODMR) of photoexcited triplet states.  

PubMed

Optically Detected Magnetic Resonance (ODMR) is a double resonance technique which combines optical measurements (fluorescence, phosphorescence, absorption) with electron spin resonance spectroscopy. After the first triplet-state ODMR experiments in zero magnetic field reported in 1968 by Schmidt and van der Waals, the number of double resonance studies on excited triplet states grew rapidly. Photosynthesis has proven to be a fruitful field of application due to the intrinsic possibility of forming photo-induced pigment triplet states in many sites of the photosynthetic apparatus. The basic principles of this technique are described and examples of application in Photosynthesis are reported. PMID:19238576

Carbonera, Donatella

2009-01-01

364

Advances in resonance based NDT for ceramic components  

NASA Astrophysics Data System (ADS)

The application of resonance based non-destructive testing methods has been providing benefit to manufacturers of metal components in the automotive and aerospace industries for many years. Recent developments in resonance based technologies are now allowing the application of resonance NDT to ceramic components including turbine engine components, armor, and hybrid bearing rolling elements. Application of higher frequencies and advanced signal interpretation are now allowing Process Compensated Resonance Testing to detect both internal material defects and surface breaking cracks in a variety of ceramic components. Resonance techniques can also be applied to determine material properties of coupons and to evaluate process capability for new manufacturing methods.

Hunter, L. J.; Jauriqui, L. M.; Gatewood, G. D.; Sisneros, R.

2012-05-01

365

Electron Spin Magnetic Resonance Force Microscopy of Nitroxide Spin Labels  

NASA Astrophysics Data System (ADS)

Nitroxide spin labels are widely used in electron spin resonance studies of biological and polymeric systems. Magnetic resonance force microscopy (MRFM) is a magnetic resonance technique that couples the high spatial resolution of a scanning probe microscope with the species selectivity of magnetic resonance. We report on our investigations of 4-amino TEMPO, a nitroxide spin label, by force-gradient MRFM. Our microscope operates at high vacuum in liquid helium, using a custom fabricated ultra-soft silicon cantilever in the magnet-on-cantilever geometry. An 18 GHz gap coupled microstripline resonator supplies the transverse field.

Moore, Eric W.; Lee, Sanggap; Hickman, Steven A.; Wright, Sarah J.; Marohn, John A.

2009-03-01

366

Nonlinear resonant ultrasound spectroscopy (NRUS) applied to damage assessment in bone  

E-print Network

Nonlinear resonant ultrasound spectroscopy (NRUS) applied to damage assessment in bone Marie 2005; revised 23 September 2005; accepted 24 September 2005 Nonlinear resonant ultrasound spectroscopy technique for fracture risk prediction.1 Other structural or material bone characteristics have been

367

Temperature Sensors Based on WGM Optical Resonators  

NASA Technical Reports Server (NTRS)

A proposed technique for measuring temperature would exploit differences between the temperature dependences of the frequencies of two different electromagnetic modes of a whispering gallery-mode (WGM) optical resonator. An apparatus based on this technique was originally intended to be part of a control system for stabilizing a laser frequency in the face of temperature fluctuations. When suitably calibrated, apparatuses based on this technique could also serve as precise temperature sensors for purposes other than stabilization of lasers. A sensor according to the proposal would include (1) a transparent WGM dielectric resonator having at least two different sets of modes characterized by different thermo-optical constants and (2) optoelectronic instrumentation for measuring the difference between the temperature-dependent shifts of the resonance frequencies of the two sets of modes.

Savchenkov, Anatoliy; Yu, Nan; Maleki, Lute; Itchenko, Vladimir; Matsko, Andrey; Strekalov, Dmitry

2008-01-01

368

New Imaging Techniques for Bone  

Microsoft Academic Search

\\u000a This chapter provides a comprehensive review of the existing imaging techniques for assessing trabecular and cortical architecture\\u000a as well as emerging advances in these areas. A brief description of the physics behind X-ray computed tomography and magnetic\\u000a resonance imaging is provided to lay the foundation for review of image acquisition techniques. Next, the authors review at\\u000a length image analysis algorithms

Suchandrima Banerjee; Roland Krug; Sven Prevrhal; Sharmila Majumdar

369

Review of Mathematical Techniques Applicable in Astrophysical Reaction Rate Theory  

E-print Network

An overview is presented on statistical techniques for the analytic evaluation of integrals for non-resonant, non-resonant depleted, non-resonant cut-off, non-resonant sccreened, and resonant thermonuclear reaction rates. The techniques are based on statistical distribution theory and the theory of Meijer's G-function and Fox's H-function. The implementation of Meijer's G-function in Mathematica constituts an additional utility for analytic manipulations and numerical computation of thermonuclear reaction rate integrals. Recent results in the astrophysical literature related to the use of analytic thermonuclear reaction rates are incorporated.

A. M. Mathai; H. J. Haubold

2002-06-23

370

Multipass modes in an open resonator  

NASA Astrophysics Data System (ADS)

The papers dealing with multipass modes in open stable resonators are reviewed. A numerical model of an axially symmetric resonator is described that permits the properties of multipass modes to be studied in wave approximation. It is shown that for Fresnel numbers larger than unity, multiple reflections of radiation from the stable resonator mirrors lead to sustained quasi-stationary field oscillations in the resonator which are indicative of the essential contribution of multipass modes. The calculations in filling the resonator with the active medium have been performed for two types of lasers: with the on-axis and off-axis gain maxima. Resonator designs are suggested, trajectory selection techniques are considered to provide high-quality radiation at large Fresnel numbers. The confocal resonator properties are analyzed in the context of competition between single-pass and multipass modes. Relying on the results of calculations for multipass mode generation, a critical analysis of the experimental works is presented suggesting a logical explanation for the peculiarities which had not been physically interpreted in the original publications. An advanced understanding of the physics of multipass mode formations allowed us to put forward a special design of stable resonators for the generation of high quality radiation in high-power lasers.

Niziev, V. G.; Grishaev, R. V.; Panchenko, V. Ya

2015-02-01

371

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

372

Detection of the Na(+)-translocating NADH-quinone reductase in marine bacteria using a PCR technique.  

PubMed

To examine the distribution of the Na(+)-translocating NADH-quinone reductase (Na(+)-NQR) among marine bacteria, we developed a simple screening method for the detection of this enzyme. By reference to the homologous sequences of the Na(+)-NQR operons from Vibrio alginolyticus and Haemophilus influenzae, a pair of primers was designed for amplification of a part of the sixth ORF (nqr6) of the Na(+)-NQR operon. When PCR was performed using genomic DNA from 13 marine bacteria, a 0.9-kbp fragment corresponding to nqr6 was amplified in 10 strains. Although there were three PCR-negative strains phylogenetically, based on the sequence of the 16S rRNA, these were placed far from the PCR-positive strains. No product was observed in the case of nonmarine bacteria. The nucleotide and predicted amino acid sequences of nqr6 were highly conserved among the PCR-positive marine bacteria. A phylogenetic analysis of marine bacteria, based on nqr6 sequencing, was performed. PMID:10779868

Kato, S; Yumoto, I

2000-04-01

373

Young's modulus measurement method for nano-scale film materials by using MEMS resonator array  

Microsoft Academic Search

This paper describes a quantitative measurement method for Young's modulus of nanometer-thick film materials by using a MEMS resonator array. The MEMS resonators fabricated by silicon micromachining techniques were designed to be driven at their resonant frequencies from 6.0 kHz to 35.5 kHz. From the difference in resonant frequencies between before and after deposition of these films onto the resonators,

D. Goto; T. Namazu; S. Inoue; T. Takeuchi; K. Murakami; E. Komatsu; Y. Kawashimo; T. Takano

2009-01-01

374

Single Molecule Electron Paramagnetic Resonance  

NASA Astrophysics Data System (ADS)

Electron paramagnetic resonance (EPR) is a powerful spectroscopic tool for studying the dynamics of biomolecular systems. EPR measurements on bulk samples using a commercial X-band spectrometer provide insight into atomic-scale structure and dynamics of ensembles of biomolecules. Separately, single molecule measurements of biomolecular systems allow researchers to capture heterogeneous behaviors that have revealed the molecular mechanisms behind many biological processes. We are merging these two powerful techniques to perform single molecule EPR. In this experiment, we selectively label double-stranded DNA molecules with nitrogen-vacancy (NV) center nanodiamonds and optically detect the magnetic resonance of the NV probe. Shifts and broadening of our EPR peaks indicate the changing position of the attached DNA relative to the applied magnetic field. Using this new technique, we have successfully measured the first EPR spectrum of a single biomolecule. By controlling the geometry of the diamond and the applied magnetic field, we will quantitatively determine the rotational and translational dynamics of single biomolecules. This research provides the foundation for an advanced single molecule magnetic resonance approach to studies of complex biomolecular systems.

Teeling-Smith, Richelle M.; Johnston-Halperin, Ezekiel; Poirier, Michael G.; Hammel, P. Chris

2013-03-01

375

Crossing simple resonances  

SciTech Connect

A simple criterion governs the beam distortion and/or loss of protons on a fast resonance crossing. Results from numerical integrations are illustrated for simple sextupole, octupole, and 10-pole resonances.

Collins, T.

1985-08-01

376

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

377

MRI (Magnetic Resonance Imaging)  

MedlinePLUS

... Radiation-Emitting Products and Procedures Medical Imaging MRI (Magnetic Resonance Imaging) Description Uses Risks/Benefits Information for ... Regulations & Performance Standards Industry Guidance Other Resources Description Magnetic resonance imaging (MRI) is a medical imaging procedure ...

378

Dismantling techniques  

SciTech Connect

Most of the dismantling techniques used in a Decontamination and Dismantlement (D and D) project are taken from conventional demolition practices. Some modifications to the techniques are made to limit exposure to the workers or to lessen the spread of contamination to the work area. When working on a D and D project, it is best to keep the dismantling techniques and tools as simple as possible. The workers will be more efficient and safer using techniques that are familiar to them. Prior experience with the technique or use of mock-ups is the best way to keep workers safe and to keep the project on schedule.

Wiese, E.

1998-03-13

379

Theoretical characterization of the collective resonance states underlying the xenon giant dipole resonance  

NASA Astrophysics Data System (ADS)

We present a detailed theoretical characterization of the two fundamental collective resonances underlying the xenon giant dipole resonance (GDR). This is achieved consistently by two complementary methods implemented within the framework of the configuration-interaction singles (CIS) theory. The first method accesses the resonance states by diagonalizing the many-electron Hamiltonian using the smooth exterior complex scaling technique. The second method involves a different application of the Gabor analysis to wave-packet dynamics. We identify one resonance at an excitation energy of 74 eV with a lifetime of 27 as and the second at 107 eV with a lifetime of 11 as . Our work provides a deeper understanding of the nature of the resonances associated with the GDR: a group of close-lying intrachannel resonances splits into two far-separated resonances through interchannel couplings involving the 4 d electrons. The CIS approach allows a transparent interpretation of the two resonances as new collective modes. Due to the strong entanglement between the excited electron and the ionic core, the resonance wave functions are not dominated by any single particle-hole state. This gives rise to plasma-like collective oscillations of the 4 d shell as a whole.

Chen, Yi-Jen; Pabst, Stefan; Karamatskou, Antonia; Santra, Robin

2015-03-01

380

Baryon Spectroscopy and Resonances  

SciTech Connect

A short review of current efforts to determine the highly excited state spectrum of QCD, and in particular baryons, using lattice QCD techniques is presented. The determination of the highly excited spectrum of QCD is a major theoretical and experimental challenge. The experimental investigation of the excited baryon spectrum has been a long-standing element of the hadronic-physics program, an important component of which is the search for so-called 'missing resonances', baryonic states predicted by the quark model based on three constituent quarks but which have not yet been observed experimentally. Should such states not be found, it may indicate that the baryon spectrum can be modeled with fewer effective degrees of freedom, such as in quark-diquark models. In the past decade, there has been an extensive program to collect data on electromagnetic production of one and two mesons at Jefferson Lab, MIT-Bates, LEGS, MAMI, ELSA, and GRAAL. To analyze these data, and thereby refine our knowledge of the baryon spectrum, a variety of physics analysis models have been developed at Bonn, George Washington University, Jefferson Laboratory and Mainz. To provide a theoretical determination and interpretation of the spectrum, ab initio computations within lattice QCD have been used. Historically, the calculation of the masses of the lowest-lying states, for both baryons and mesons, has been a benchmark calculation of this discretized, finite-volume computational approach, where the aim is well-understood control over the various systematic errors that enter into a calculation; for a recent review. However, there is now increasing effort aimed at calculating the excited states of the theory, with several groups presenting investigations of the low-lying excited baryon spectrum, using a variety of discretizations, numbers of quark flavors, interpolating operators, and fitting methodologies. Some aspects of these calculations remain unresolved and are the subject of intense effort, notably the ordering of the Roper resonance in the low-lying Nucleon spectrum.

Robert Edwards

2011-12-01

381

Optically Enhanced Magnetic Resonance  

E-print Network

Optically Enhanced Magnetic Resonance Dieter Suter Universit¨at Dortmund, Germany 1 Introduction 1.1 Motivation The physical mechanism of nuclear magnetic resonance spectroscopy, the excitation of transitions. In most magnetic resonance experiments, these couplings are used to monitor the environment of the nuclei

Suter, Dieter

382

Magnetic Resonance Spectroscopy (MRS)  

E-print Network

Magnetic Resonance Spectroscopy (MRS) and Its Application in Alzheimer's Disease PRAVAT K. MANDAL1, Pennsylvania ABSTRACT: Magnetic resonance spectroscopy (MRS) is a noninvasive tool to measure the chemical; PRESS; STEAM; 2D MRS; Alzheimer's disease I. INTRODUCTION Magnetic resonance spectroscopy (MRS) is a rap

Mandal, Pravat K.

383

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

384

ELECTRON PARAMAGNETIC RESONANCE SPECTROSCOPY  

E-print Network

CHAPTER 3 ELECTRON PARAMAGNETIC RESONANCE SPECTROSCOPY 1 Sergei A. Dikanov and 2 Antony R. Crofts 1 for the investigation of unpaired electron spins. Two terms are used in the literature: electron paramagnetic resonance (EPR) and electron spin resonance (ESR). We will use the first term in this chapter. During the sixty

Crofts, Antony R.

385

An Inexpensive Resonance Demonstration  

ERIC Educational Resources Information Center

The phenomenon of resonance is applicable to almost every branch of physics. Without resonance, there wouldn't be televisions or stereos, or even swings on the playground. However, resonance also has undesirable side effects such as irritating noises in the car and the catastrophic events such as helicopters flying apart. In this article, the…

Dukes, Phillip

2005-01-01

386

Resonance transformer power conditioners  

Microsoft Academic Search

Designs for power conditioning systems based on the resonance transformer have been developed for applications requiring compact, lightweight power supplies ranging from average power levels of 10 kW to over 1 MW. The resonance transformer is a patented concept which depends on a set of resonant LC circuits to produce transformer-like voltage or current gain. Because this approach does not

R. M. Ness; S. G. E. Pronko; J. R. Cooper; E. Y. Chu

1990-01-01

387

[Magnetic resonance spectroscopy].  

PubMed

Life-time diagnosis of the initial pathological shifts in the organism remains an and still unsolved important problem of modern medicine. Magnetic resonance spectroscopy based on the nuclear magnetic resonance phenomenon is one of the methods which can help to solve this problem. Modern reports about the use of magnetic resonance spectroscopy in the diagnosis of various diseases are reviewed. PMID:11521591

Tsa?, I V; Kulikov, S A; Kozinets, G I

2001-06-01

388

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

389

Observation and characterization of mode splitting in microsphere resonators in aquatic environment  

E-print Network

Whispering gallery mode (WGM) optical resonators utilizing resonance shift (RS) and mode splitting (MS) techniques have emerged as highly sensitive platforms for label-free detection of nano-scale objects. RS method has been demonstrated in various resonators in air and liquid. MS in microsphere resonators has not been achieved in aqueous environment up to date, despite its demonstration in microtoroid resonators. Here, we demonstrate scatterer-induced MS of WGMs in microsphere resonators in water. We determine the size range of particles that induces MS in a microsphere in water as a function of resonator mode volume and quality factor. The results are confirmed by the experimental observations.

Woosung, Kim; Zhu, Jiangang; Yang, Lan

2011-01-01

390

Stiffness-compensated temperature-insensitive micromechanical resonators  

Microsoft Academic Search

Polysilicon ?mechanical resonators utilizing a novel temperature-dependent electrical stiffness design technique to compensate for temperature-induced frequency shifts have been demonstrated with greatly reduced temperature coefficients (TCf 's) on the order of -0.24 ppm\\/°C, which is 67 times smaller than exhibited by previous uncompensated resonators. With this new resonator design, the total frequency excursion over a 300 K to 380 K

Wan-Thai Hsu; C. T.-C. Nguyen

2002-01-01

391

Stressed Silicon Nitride Nanomechanical Resonators at Helium Temperatures  

NASA Astrophysics Data System (ADS)

We have characterized the mechanical resonance properties (both linear and nonlinear) of various doubly-clamped silicon nitride nanomechanical resonators, each with a different intrinsic tensile stress. The measurements were carried out at 4 K and the magnetomotive technique was used to drive and detect the motion of the beams. The resonant frequencies of the beams are in the megahertz range, with quality factors of the order of 104. We also measure the dynamic range of the beams and their nonlinear (Duffing) behaviour.

Defoort, M.; Lulla, K. J.; Blanc, C.; Ftouni, H.; Bourgeois, O.; Collin, E.

2013-06-01

392

An encapsulating meta-molecule: U resonator containing spiral line  

NASA Astrophysics Data System (ADS)

A new kind of planar metamaterial is investigated. It consists of meta-molecules where a first resonator encapsulates a second resonator. The near-field coupling between these resonators is the dominating effect determining the characteristics of the material and is discussed in detail at a physical level. The technique of encapsulating allows both to miniaturize the unit cell, which is advantageous with respect to making the material homogeneous, and to invoke strong coupling, which is advantageous for tuning the material.

Yan, Sen; Vandenbosch, Guy A. E.

2014-11-01

393

Hip Prosthesis Detection based on Complex Natural Resonances.  

PubMed

Resonance based radar target detection has been applied to Ground Penetrating Radar (GPR) applications for the detection and recognition of landmines. Target detection is achieved by searching for certain target dependent Complex Natural Resonances (CNRs), which could be considered as a feature set for identification. In this paper, detection of a hip prosthesis under human tissues using resonance based target detection technique is investigated. PMID:17282504

Lui, Hoi-Shun; Shuley, Nicholas; Crozier, Stuart

2005-01-01

394

Boundary element method for resonances in dielectric microcavities  

E-print Network

A boundary element method based on a Green's function technique is introduced to compute resonances with intermediate lifetimes in quasi-two-dimensional dielectric cavities. It can be applied to single or several optical resonators of arbitrary shape, including corners, for both TM and TE polarization. For cavities with symmetries a symmetry reduction is described. The existence of spurious solutions is discussed. The efficiency of the method is demonstrated by calculating resonances in two coupled hexagonal cavities.

Jan Wiersig

2002-12-10

395

Science Drivers and Technical Challenges for Advanced Magnetic Resonance  

SciTech Connect

This report recaps the "Science Drivers and Technical Challenges for Advanced Magnetic Resonance" workshop, held in late 2011. This exploratory workshop's goal was to discuss and address challenges for the next generation of magnetic resonance experimentation. During the workshop, participants from throughout the world outlined the science drivers and instrumentation demands for high-field dynamic nuclear polarization (DNP) and associated magnetic resonance techniques, discussed barriers to their advancement, and deliberated the path forward for significant and impactful advances in the field.

Mueller, Karl T.; Pruski, Marek; Washton, Nancy M.; Lipton, Andrew S.

2013-03-07

396

Miniaturization of metamaterial electrical resonators at the terahertz spectrum  

NASA Astrophysics Data System (ADS)

An efficient methodology for the modification of electrical resonators in order to be readily applicable at the terahertz regime is developed in this paper. To this aim, the proposed miniaturization technique starts from the conventional resonator which, without any change, exhibits the lowest possible electrical resonance for minimum dimensions. Subsequently, a set of interdigital capacitors is embedded in the original structure to increase capaci- tance, while their impact on the main resonance is investigated through computational simulations. Furthermore, to augment the inductance of the initial resonator, and, hence reduce the resonance frequency, the concept of spiral inductor elements is introduced. Again, results for the featured configuration with the additional elements are numerically obtained and all effects due to their presence are carefully examined. Finally, the new alterations are combined together and their in influence on the resonance position and quality is thoroughly studied.

Karamanos, Theodosios D.; Kantartzis, Nikolaos V.

2014-05-01

397

Pyknometric volume measurement of a quasispherical resonator  

NASA Astrophysics Data System (ADS)

We have measured the internal volume of a 1 litre, diamond-turned copper quasispherical resonator with a fractional uncertainty of approximately 1 part in 106 using two independent techniques. This is in response to the need for a uniquely accurate measurement of resonator volume, for the purpose of measuring the Boltzmann constant in pursuit of the redefinition of the kelvin. The first technique is a pyknometric measurement using water as a liquid of known density. We describe the development of a procedure that results in stable, reproducible volume measurements. We provide a detailed discussion of the factors that affect the water density, such as dissolved gases. The second technique is microwave resonance spectroscopy. Here, we measure the resonant frequencies of the TM1n modes and relate them to the dimensions of the resonator. We evaluate the frequency perturbations that arise from the coupling waveguides and the electrical resistivity of the copper surface. The results of the microwave measurements show evidence of a dielectric coating on the surface. We propose that this is an oxide layer and estimate its thickness from the microwave data. Finally, we compare the volume estimates from the two methods, and find that the difference is within the combined uncertainty.

Underwood, R.; Davidson, S.; Perkin, M.; Morantz, P.; Sutton, G.; de Podesta, M.

2012-06-01

398

Resonant and non-resonant magnetic scattering  

SciTech Connect

The tunability and the polarization of synchrotron radiation open upon new possibilities for the study of magnetism. Studies on magnetic materials performed at the National Synchrotron Light Source are reviewed, and thy fall into four areas: structure, evolution of magnetic order, separation of L and S, and resonance effects. In the vicinity of atomic absorption edges, the Faraday effect, magnetic circular dichroism, and resonant magnetic scattering are all related resonance effects which measure the spin polarized density of states. The production and analysis of polarized beams are discussed in the context of the study of magnetism with synchrotron radiation.

McWhan, D.B.; Hastings, J.B.; Kao, C.C.; Siddons, D.P.

1991-01-01

399

Resonant and non-resonant magnetic scattering  

SciTech Connect

The tunability and the polarization of synchrotron radiation open upon new possibilities for the study of magnetism. Studies on magnetic materials performed at the National Synchrotron Light Source are reviewed, and thy fall into four areas: structure, evolution of magnetic order, separation of L and S, and resonance effects. In the vicinity of atomic absorption edges, the Faraday effect, magnetic circular dichroism, and resonant magnetic scattering are all related resonance effects which measure the spin polarized density of states. The production and analysis of polarized beams are discussed in the context of the study of magnetism with synchrotron radiation.

McWhan, D.B.; Hastings, J.B.; Kao, C.C.; Siddons, D.P.

1991-12-31

400

MEMS metrology techniques  

NASA Astrophysics Data System (ADS)

The MEMS industry currently produces over $13 billion in annual revenue, with devices in such diverse applications as blood pressure sensors, projection displays, optical switches, printers, hard drives, and gyroscopes. As production techniques improve, ever more functions may be served by MEMS, and the industry is growing at an annual rate of more than 15%. The large diversity of MEMS leads to many challenges in metrology, as each design has different critical factors which will affect its performance. Unlike traditional semiconductor devices, MEMS require characterization both in their static state and under actuation. Parameters of interest include shape, dimensions, surface roughness, sidewall angles, film thickness, residual stress, feature volumes, response times, thermal properties, resonance frequencies, stiction, environmental immunity and more. This talk will discuss the strengths and weaknesses of a variety of techniques for MEMS surface metrology. Bright- and dark-field microscopy, scanning electron microscopy, contact and non-contact surface profilometry, atomic force microscopy, laser Doppler vibrometry and digital holography are some of the primary techniques used to evaluate MEMS surfaces and motion. While no single technique can fully characterize all MEMS devices, or even one device under all conditions, the utility of each of the different types of instruments is increasing as they are pushed by MEMS and other industries to provide more characterization capability. With a broad understanding of the various metrology techniques available, the one or few critical instruments to measure a given class of devices will hopefully be more easily understood.

Novak, Erik

2004-12-01

401

MEMS metrology techniques  

NASA Astrophysics Data System (ADS)

The MEMS industry currently produces over $13 billion in annual revenue, with devices in such diverse applications as blood pressure sensors, projection displays, optical switches, printers, hard drives, and gyroscopes. As production techniques improve, ever more functions may be served by MEMS, and the industry is growing at an annual rate of more than 15%. The large diversity of MEMS leads to many challenges in metrology, as each design has different critical factors which will affect its performance. Unlike traditional semiconductor devices, MEMS require characterization both in their static state and under actuation. Parameters of interest include shape, dimensions, surface roughness, sidewall angles, film thickness, residual stress, feature volumes, response times, thermal properties, resonance frequencies, stiction, environmental immunity and more. This talk will discuss the strengths and weaknesses of a variety of techniques for MEMS surface metrology. Bright- and dark-field microscopy, scanning electron microscopy, contact and non-contact surface profilometry, atomic force microscopy, laser Doppler vibrometry and digital holography are some of the primary techniques used to evaluate MEMS surfaces and motion. While no single technique can fully characterize all MEMS devices, or even one device under all conditions, the utility of each of the different types of instruments is increasing as they are pushed by MEMS and other industries to provide more characterization capability. With a broad understanding of the various metrology techniques available, the one or few critical instruments to measure a given class of devices will hopefully be more easily understood.

Novak, Erik

2005-01-01

402

High-Lying Photodetachment Resonance in Aluminum  

NASA Astrophysics Data System (ADS)

A resonance has been observed in the photodetachment cross section of Al^- near the threshold of the 3s^24p;^2P excited state of neutral Al. Previously, we have measured a large resonance below the 3s^24s;^2S first excited state of Al.footnote B. J. Davies, C. W. Ingram, D. J. Larson, C. Liu and A. F. Starace, submitted to Phys. Rev. A (1996) We plan to use state-selective ionization to probe the higher resonance further. Atoms left in the 3s^23d;^2D state as a result of photodetachment will be detected via resonant photoexcitation to a Rydberg state followed by field ionization. This technique allows for greater sensitivity than previous measurements because of its state selective nature.

Ingram, C. W.; Larson, D. J.; Thoma, J. E.

1997-04-01

403

Tunable resonant structures for photonic integrated circuits  

NASA Astrophysics Data System (ADS)

Photonics is an evolving field allowing for optical devices to be made cost effectively using standard semiconductor fabrication techniques, which in turn enables integration with microelectronic chips. Chip scale photonics will play an increasing role in the future of communications as the demand for bandwidth and reduced power consumption per bit continues to grow. Tunable optical circuit components are one of the essential technologies in the development of photonic analogues for classical electronic devices, where tunable photonic resonant structures allow for altering of their electromagnetic spectrum and find applications in optical switching, filtering, buffering, lasers and biosensors. The scope of this work is focused on tunable resonant structures for photonic integrated circuits. Specifically, this work demonstrates active tuning of silicon photonic resonant structures using the properties of dye doped nematic liquid crystals, temperature stabilization of silicon photonics using the passive properties of liquid crystals, and the effects of low density plasma enhanced chemical vapor deposition (PECVD) claddings on ring resonator device performance.

Ptasinski, Joanna Nina

404

Hidden Sector Photon Coupling of Resonant Cavities  

E-print Network

Many beyond the standard model theories introduce light paraphotons, a hypothetical spin-1 field that kinetically mixes with photons. Microwave cavity experiments have traditionally searched for paraphotons via transmission of power from an actively driven cavity to a passive receiver cavity, with the two cavities separated by a barrier that is impenetrable to photons. We extend this measurement technique to account for two-way coupling between the cavities and show that the presence of a paraphoton field can alter the resonant frequencies of the coupled cavity pair. We propose an experiment that exploits this effect and uses measurements of a cavities resonant frequency to constrain the paraphoton-photon mixing parameter, chi. We show that such an experiment can improve sensitivity to chi over existing experiments for paraphoton masses less than the resonant frequency of the cavity, and eliminate some of the most common systematics for resonant cavity experiments.

Stephen R. Parker; Gray Rybka; Michael E. Tobar

2013-04-25

405

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

406

Culinary Techniques  

NSDL National Science Digital Library

This website is a simple, quick reference for a variety of basic culinary techniques. It covers a wide variety of techniques that some recipes or class situations might assume are basic but in fact are not necessarily so. Techniques from preparing stock and mayonnaise, to poaching and saut�ing are included. While not designed specifically as an educational site, the technique descriptions are handy and easily found in a pinch, and act as a simple and relevant source of reference for anyone involved in the culinary arts.

407

Resonantly detecting axion-mediated forces with nuclear magnetic resonance.  

PubMed

We describe a method based on precision magnetometry that can extend the search for axion-mediated spin-dependent forces by several orders of magnitude. By combining techniques used in nuclear magnetic resonance and short-distance tests of gravity, our approach can substantially improve upon current experimental limits set by astrophysics, and probe deep into the theoretically interesting regime for the Peccei-Quinn (PQ) axion. Our method is sensitive to PQ axion decay constants between 10(9) and 10(12) GeV or axion masses between 10(-6) and 10(-3) eV, independent of the cosmic axion abundance. PMID:25361250

Arvanitaki, Asimina; Geraci, Andrew A

2014-10-17

408

Resonant detection of axion mediated forces with Nuclear Magnetic Resonance  

E-print Network

We describe a method based on precision magnetometry that can extend the search for axion-mediated spin-dependent forces by several orders of magnitude. By combining techniques used in nuclear magnetic resonance and short-distance tests of gravity, our approach can substantially improve upon current experimental limits set by astrophysics, and probe deep into the theoretically interesting regime for the Peccei-Quinn (PQ) axion. Our method is sensitive to PQ axion decay constants between 10^9 and 10^12 GeV or axion masses between 10^-6 and 10^-3 eV, independent of the cosmic axion abundance.

Asimina Arvanitaki; Andrew A. Geraci

2014-03-05

409

Resonantly Detecting Axion-Mediated Forces with Nuclear Magnetic Resonance  

NASA Astrophysics Data System (ADS)

We describe a method based on precision magnetometry that can extend the search for axion-mediated spin-dependent forces by several orders of magnitude. By combining techniques used in nuclear magnetic resonance and short-distance tests of gravity, our approach can substantially improve upon current experimental limits set by astrophysics, and probe deep into the theoretically interesting regime for the Peccei-Quinn (PQ) axion. Our method is sensitive to PQ axion decay constants between 109 and 1012 GeV or axion masses between 10-6 and 10-3 eV, independent of the cosmic axion abundance.

Arvanitaki, Asimina; Geraci, Andrew A.

2014-10-01

410

Split-resonator integrated-post MEMS gyroscope  

NASA Technical Reports Server (NTRS)

A split-resonator integrated-post vibratory microgyroscope may be fabricated using micro electrical mechanical systems (MEMS) fabrication techniques. The microgyroscope may include two gyroscope sections bonded together, each gyroscope section including resonator petals, electrodes, and an integrated half post. The half posts are aligned and bonded to act as a single post.

Bae, Youngsam (Inventor); Hayworth, Ken J. (Inventor); Shcheglov, Kirill V. (Inventor)

2004-01-01

411

Plasma Diagnostics with a Microwave Fabry-Perot Resonator  

Microsoft Academic Search

Plasma diagnostics with a confocal spherical mirror Fabry-Perot resonator are examined. The diagnostic equations are presented and experimentally verified. The measurable ranges of electron densities and collision frequencies are treated both theoretically and by example. A brief background of the theory of the resonator is summarized (with references) from the literature. A perturbational technique for measuring collision frequency, or Q

R. J. Chaffin; J. B. Beyer

1968-01-01

412

Hybrid Magnetic Resonance Angiography and Quantitative Volume Flow Measurement  

Microsoft Academic Search

Volume blood flow rate correlates directly with oxygen delivery for aerobic metabolism and is thus clinically more significant than velocity in the diagnosis of vascular diseases. In this dissertation, an magnetic resonance imaging (MRI) technique has been developed to directly measure flow rate. A two echo hybrid magnetic resonance angiography (MRA) pulse sequence has been designed and implemented to obtain

Ping Hou

1993-01-01

413

Resonant ultrasound spectroscopy using optical excitation and detection  

Microsoft Academic Search

We propose a new technique for Resonant Ultrasound Spectroscopy (RUS), using chopped optical excitation and interferometric detection with focused laser beams. Spheroidal vibrational modes of a sintered, polished silicon nitride sphere of diameter ?7 mm were observed, and the elastic constants of the sample derived. Varying the excitation geometry affects the relative strengths of the resonance peaks.

Satoru Sato; Katsuhiko Inagaki; Vitalyi E. Gusev; Oliver B. Wright

1999-01-01

414

Resonant ultrasound spectroscopy using optical excitation and detection  

Microsoft Academic Search

We propose a new technique for Resonant Ultrasound Spectroscopy (RUS), using chopped optical excitation and interferometric detection with focused laser beams. Spheroidal vibrational modes of a sintered, polished silicon nitride sphere of diameter ~7 mm were observed, and the elastic constants of the sample derived. Varying the excitation geometry affects the relative strengths of the resonance peaks.

Satoru Sato; Katsuhiko Inagaki; Vitalyi E. Gusev; Oliver B. Wright

1999-01-01

415

Boundary element method for resonances in dielectric microcavities  

Microsoft Academic Search

A boundary element method based on a Green function technique is introduced to compute resonances with intermediate lifetimes in quasi-two-dimensional dielectric cavities. It can be applied to single or several optical resonators of arbitrary shape, including corners, for both TM and TE polarization. For cavities with symmetries a symmetry reduction is described. The existence of spurious solutions is discussed. The

Jan Wiersig

2003-01-01

416

Analysis of tokamak collector probes by resonance ionization spectroscopy  

Microsoft Academic Search

Resonance ionization spectroscopy has been applied to analyze tokamak collector probes. The edge plasma of the MT-1 tokamak was investigated using nonintrinsic sodium impurities injected by the laser blow-off technique. Silicon single crystal deposition probes were analyzed by laser atomization, followed by the resonance ionization method. The unique sensitivity of the selective photoionization made it possible to determine the radial

M. Á. Kedves; J. S. Bakos; I. B. Földes; P. N. Ignácz; G. Kocsis

1990-01-01

417

Abstract-In this study, imaging of electrical current density in conducting objects, which contain nuclear magnetic resonance  

E-print Network

nuclear magnetic resonance (NMR) active nuclei is planned using 0.15T Magnetic Resonance Imaging (MRI. Experiments performed on several phantoms and the results are presented. Keywords - Magnetic Resonance Imaging]. Nuclear magnetic resonance imaging techniques can be used to image the current density J . Joy et al. [6

Eyüboðlu, Murat

418

Phase versus flux coupling between resonator and superconducting flux qubit  

NASA Astrophysics Data System (ADS)

The dispersive coupling of qubits to microwave resonators has become widely used for qubit readout. Recent advances in coupling qubits to 3D resonators have demonstrated the importance of the nature of the qubit-resonator coupling in determining the qubit relaxation and decoherence times, T1 and T2^*. We study the effect of phase versus flux coupling on flux qubits coupled to planar resonators. Using an aluminum shadow evaporation technique we fabricate a low-loss planar resonator, consisting of a meandering inductor and interdigitated capacitor, and a flux qubit, all in a single processing step. Whereas the qubit and resonator are always flux coupled via a geometric mutual inductance, a phase coupling can be added by including a shared trace between the qubit and resonator. This technique allows us to control both the magnitude and nature of the qubit-resonator coupling without significantly affecting either the qubit or resonator design. We characterize the dependence of the qubit parameters T1, T2^*, and spin echo time Techo on the resonator coupling parameters to gain insight into possible sources of decoherence and loss.

Birenbaum, J. S.; O'Kelley, S. R.; Anton, S. M.; Nugroho, C. D.; Orlyanchik, V.; Dove, A. H.; Yoscovits, Z. R.; Olson, G. A.; van Harlingen, D. J.; Eckstein, J.; Braje, D. A.; Johnson, R. C.; Oliver, W. D.; Clarke, John

2013-03-01

419

Magnetic resonance image enhancement using V-filter  

SciTech Connect

The purpose of this study is to present a method of boundary enhancement algorithms for magnetic resonance images using a V-filter. The boundary of the brain tumor was precisely extracted by the region segmentation techniques.

Yamamoto, H.; Sugita, K. (School of Health Sciences, Okayama Univ., Shikata, Okayama 700 (JP)); Kanzaki, N.; Johja, I.; Hiraki, Y. (Okayama Univ. (Japan). School of Medicine); Kuwahara, M. (Osaka Industrial Univ., Nakagaito, Daito 574 (JP))

1990-06-01

420

Magnetic Resonance Imaging Method For Estimating Cone Of Uncertainty  

Cancer.gov

The National Institute of Child Health and Human Development (NICHD), Section on Tissue Biophysics and Biomimetics, is seeking statements of capability or interest from parties interested in collaborative research to further develop, evaluate, or commercialize magnetic resonance imaging techniques.

421

Electron Spin Resonance in Studies of Membranes and Proteins  

NSDL National Science Digital Library

We provide a review of current electron spin resonance (ESR) techniques for studying basic molecular mechanisms in membranes and proteins by using nitroxide spin labels. We illustrate these capabilities with recent examples.

P. P. Borbat (Cornell University; Baker Laboratory of Chemistry and Chemical Biology)

2001-01-12

422

Novel Detection Schemes of Nuclear Magnetic Resonance and Magnetic Resonance Imaging: Applications from Analytical Chemistry to Molecular Sensors  

Microsoft Academic Search

Nuclear magnetic resonance (NMR) is a well-established analytical technique in chemistry. The ability to precisely control the nuclear spin interactions that give rise to the NMR phenomenon has led to revolutionary advances in fields as diverse as protein structure determination and medical diagnosis. Here, we discuss methods for increasing the sensitivity of magnetic resonance experiments, moving away from the paradigm

Elad Harel; Leif Schröder; Shoujun Xu

2008-01-01

423

Imaging Intelligence with Proton Magnetic Resonance Spectroscopy  

ERIC Educational Resources Information Center

Proton magnetic resonance spectroscopy ([to the first power]H-MRS) is a technique for the assay of brain neurochemistry "in vivo." N-acetylaspartate (NAA), the most prominent metabolite visible within the [to the first power]H-MRS spectrum, is found primarily within neurons. The current study was designed to further elucidate NAA-cognition…

Jung, Rex E.; Gasparovic, Charles; Chavez, Robert S.; Caprihan, Arvind; Barrow, Ranee; Yeo, Ronald A.

2009-01-01

424

Single-Molecule Fluorescence Resonance Energy Transfer  

Microsoft Academic Search

Fluorescent resonance energy transfer (FRET) is a powerful technique for studying conformational distribution and dynamics of biological molecules. Some conformational changes are difficult to synchronize or too rare to detect using ensemble FRET. FRET, detected at the single-molecule level, opens up new opportunities to probe the detailed kinetics of structural changes without the need for synchronization. Here, we discuss practical

Taekjip Ha

2001-01-01

425

Magnetic resonance urography in pediatric urology  

Microsoft Academic Search

Purpose of reviewMagnetic resonance urography (MRU) has emerged as a powerful diagnostic tool in the evaluation of the pediatric genitourinary tract. The purpose of this review is to familiarize the reader with the basic techniques, strengths and limitations, as well as the current and potential future applications of MRU in pediatric urology.

Wolfgang H. Cerwinka; J. Damien Grattan-Smith; Andrew J. Kirsch

2008-01-01

426

Optical microdiscus resonators by flattening microspheres  

NASA Astrophysics Data System (ADS)

A "soften-and-squash" fabrication technique has been demonstrated to controllably deform optical microspheres and form microdiscus resonators with improved surface quality. The characteristic shape of the microdiscus results in superior mode control, and the annealing involved in the fabrication process leads to quality factors (Q) exceeding 105, which is about two orders of magnitude higher than the initial microspheres.

Senthil Murugan, Ganapathy; Wilkinson, James S.; Zervas, Michalis N.

2012-08-01

427

Resonant Ultrasound Spectroscopy of Human Bone  

Microsoft Academic Search

Resonant ultrasound spectroscopy mmethod is used to study the elastic properties of human bone. A small specimen of humerus bone was cut from human cadaver and prepared for use in this investigation. Our measured values of the elastic constants will be presented and compared with published values that were obtained using different techniques.

Fouzi Arammash; Ming Yin; Harry Preston

2003-01-01

428

Internal friction studies by resonant ultrasound spectroscopy  

Microsoft Academic Search

A description is given of the use of resonant ultrasound spectroscopy (RUS) to study internal friction in solids. The technique is applicable to a wide range of sample sizes and shapes. A method to extract the internal friction from the RUS spectrum in the presence of a coherent background signal is discussed. RUS has been used to study the internal

R. G. Leisure; K. Foster; J. E. Hightower; D. S. Agosta

2004-01-01

429

Titration Techniques  

Microsoft Academic Search

Significant attention is paid to the proper technique for reading a meniscus. Video shows meniscus-viewing techniques for colorless and dark liquids and the consequences of not reading a meniscus at eye level. Lessons are provided on approaching the end point, focusing on end point colors produced via different commonly used indicators. The concept of a titration curve is illustrated by

Jerrold J. Jacobsen; Kelly Houston Jetzer; Néha Patani; John Zimmerman; Gerald Zweerink

1995-01-01

430

Theoretical characterization of the collective resonance states underlying the xenon giant dipole resonance  

E-print Network

We present a detailed theoretical characterization of the two fundamental collective resonances underlying the xenon giant dipole resonance (GDR). This is achieved consistently by two complementary methods implemented within the framework of the configuration-interaction singles (CIS) theory. The first method accesses the resonance states by diagonalizing the many-electron Hamiltonian using the smooth exterior complex scaling technique. The second method involves a new application of the Gabor analysis to wave-packet dynamics. We identify one resonance at an excitation energy of 74 eV with a lifetime of 27 as, and the second at 107 eV with a lifetime of 11 as. Our work provides a deeper understanding of the nature of the resonances associated with the GDR: a group of close-lying intrachannel resonances splits into two far-separated resonances through interchannel couplings involving the 4d electrons. The CIS approach allows a transparent interpretation of the two resonances as new collective modes. Due to the...

Chen, Yi-Jen; Karamatskou, Antonia; Santra, Robin

2015-01-01

431

Photocurrent mapping of near-field optical antenna resonances  

Microsoft Academic Search

An increasing number of photonics applications make use of nanoscale optical antennas that exhibit a strong, resonant interaction with photons of a specific frequency. The resonant properties of such antennas are conventionally characterized by far-field light-scattering techniques. However, many applications require quantitative knowledge of the near-field behaviour, and existing local field measurement techniques provide only relative, rather than absolute, data.

Edward S. Barnard; Ragip A. Pala; Mark L. Brongersma

2011-01-01

432

Coexistence of Antiferromagnetism with Superconductivity in CePt2In7: Microscopic Phase Diagram Determined by In115 NMR and NQR  

NASA Astrophysics Data System (ADS)

Single crystals of the heavy-fermion antiferromagnet CePt2In7 with a Néel temperature (TN) of 5.2 K at ambient pressure have been investigated by zero-field In115-nuclear magnetic and quadrupole resonance measurements as a function of applied pressure. Within the antiferromagnetic state, the character of Ce's 4f electron appears to change from localized to itinerantlike at P*˜2.4 GPa, approximately the pressure where superconductivity first emerges. With increased pressure, the superconducting transition Tc reaches a maximum just at or slightly before antiferromagnetic order disappears, and not at the pressure Pc˜3.4 GPa, where the steeply decreasing Néel boundary extrapolates to zero temperature. For P >Pc, the spin relaxation rate drops sharply by more than 2 orders of magnitude at Tc, suggestive of a first-order transition.

Sakai, H.; Tokunaga, Y.; Kambe, S.; Ronning, F.; Bauer, E. D.; Thompson, J. D.

2014-05-01

433

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

434

Coherence assisted resonance with sub-lifetime-limited linewidth  

E-print Network

We demonstrate a novel approach to obtain resonance linewidth below that limited by coherence lifetime. Cross correlation between induced intensity modulation of two lasers coupling the target resonance exhibits a narrow spectrum. 1/30 of the lifetime-limited width was achieved in a proof-of-principle experiment where two ground states are the target resonance levels. Attainable linewidth is only limited by laser shot noise in principle. Experimental results agree with an intuitive analytical model and numerical calculations qualitatively. This technique can be easily implemented and should be applicable to many atomic, molecular and solid state spin systems for spectroscopy, metrology and resonance based sensing and imaging.

Lei, Feng; Jiang, Liang; Wen, Jianming; Xiao, Yanhong

2012-01-01

435

Coherence assisted resonance with sub-lifetime-limited linewidth  

E-print Network

We demonstrate a novel approach to obtain resonance linewidth below that limited by coherence lifetime. Cross correlation between induced intensity modulation of two lasers coupling the target resonance exhibits a narrow spectrum. 1/30 of the lifetime-limited width was achieved in a proof-of-principle experiment where two ground states are the target resonance levels. Attainable linewidth is only limited by laser shot noise in principle. Experimental results agree with an intuitive analytical model and numerical calculations qualitatively. This technique can be easily implemented and should be applicable to many atomic, molecular and solid state spin systems for spectroscopy, metrology and resonance based sensing and imaging.

Feng Lei; Pengxiong Li; Liang Jiang; Jianming Wen; Yanhong Xiao

2012-08-31

436

Large mode radius resonators  

NASA Technical Reports Server (NTRS)

Resonator configurations permitting operation with large mode radius while maintaining good transverse mode discrimination are considered. Stable resonators incorporating an intracavity telescope and unstable resonator geometries utilizing an output coupler with a Gaussian reflectivity profile are shown to enable large radius single mode laser operation. Results of heterodyne studies of pulsed CO2 lasers with large (11mm e sup-2 radius) fundamental mode sizes are presented demonstrating minimal frequency sweeping in accordance with the theory of laser-induced medium perturbations.

Harris, Michael R.

1987-01-01

437

Acoustic Levitator Maintains Resonance  

NASA Technical Reports Server (NTRS)

Transducer loading characteristics allow resonance tracked at high temperature. Acoustic-levitation chamber length automatically adjusted to maintain resonance at constant acoustic frequency as temperature changes. Developed for containerless processing of materials at high temperatures, system does not rely on microphones as resonance sensors, since microphones are difficult to fabricate for use at temperatures above 500 degrees C. Instead, system uses acoustic transducer itself as sensor.

Barmatz, M. B.; Gaspar, M. S.

1986-01-01

438

On open electromagnetic resonators: relation between interferometers and resonators  

SciTech Connect

The physical difference between the concepts 'Fabry-Perot interferometer' and 'open resonator' is discussed. It is shown that the use of the term 'Fabry-Perot resonator' for open laser resonators is incorrect both from the historical viewpoint and from the viewpoint of the physical meaning of the processes occurring in these resonators. (laser beams and resonators)

Manenkov, Aleksandr A; Bykov, Vladimir P; Kuleshov, N V [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2010-05-26

439

The Magnetic Resonance Force Microscope P. Chris Hammel and Denis V. Pelekhov  

E-print Network

The Magnetic Resonance Force Microscope P. Chris Hammel and Denis V. Pelekhov Ohio State University of Magnetic Resonance 10 5 Applications 16 6 Conclusions 24 Acknowledgments 24 References 24 1 INTRODUCTION The emerging technique of magnetic resonance force microscopy (MRFM) (Sidles, 1991) was conceived by Sidles

Hammel, P. Chris

440

MODULE SPECIFICATION WORD TEMPLATE POSTGRADUATE PROGRAMMES Module name Clinical Applications of Medical Magnetic Resonance  

E-print Network

Applications of Medical Magnetic Resonance Module code RDM017 School School of Health Sciences Department the various Medical Magnetic Resonance techniques and provide the clinical radiographer with the knowledge with current trends within Medical Magnetic Resonance Imaging through constantly reviewing the appropriate

Weyde, Tillman

441

Fast approximate solution of Bloch equation for simulation of RF artifacts in Magnetic Resonance Imaging  

E-print Network

Fast approximate solution of Bloch equation for simulation of RF artifacts in Magnetic Resonance, France SUMMARY The technique used to spot information in Magnetic Resonance Imaging (MRI) uses size. key words: Bloch equation, magnetic resonance imaging, Fourier series expansion, Floquet theory 1

Paris-Sud XI, Université de

442

Current and future applications of in vitro magnetic resonance spectroscopy in hepatobiliary disease  

Microsoft Academic Search

Nuclear magnetic resonance spectroscopy allows the study of cellular biochemistry and metabolism, both in the whole body in vivo and at higher magnetic fi eld strengths in vitro . Since the technique is non-invasive and non-selective, magnetic resonance spectroscopy methodologies have been widely applied in biochemistry and medicine. In vitro magnetic resonance spectroscopy studies of cells, body fl uids and

I Jane Cox; Amar Sharif; Jeremy FL Cobbold; Howard C Thomas; Simon D Taylor-Robinson

443

Superconducting tests of beta = 0. 1 and beta = 0. 2 resonators  

SciTech Connect

We have cooled down, multipactor conditioned, tested, helium conditioned, and retested several low beta (0.10) and two high beta (0.21) lead plated copper quarter-wave resonators. We discuss the choice of the quarter-wave resonator and of the lead plated copper technology. We describe the fabrication and present our techniques for conditioning the resonators. Performances are presented.

Storm, D.W.; Amsbaugh, J.F.; Corcoran, D.T.; Howe, M.A.

1986-05-01

444

Investigation of bovine bone by resonant ultrasound spectroscopy and transmission ultrasound  

E-print Network

1 Investigation of bovine bone by resonant ultrasound spectroscopy and transmission ultrasound T characterization of properties, it is also necessary to study oblique cut specimens. Resonant ultrasound spectroscopy (RUS, Fig. 1b) is a recent technique which involves scanning the resonance structure of a compact

Lakes, Roderic

445

A Bayesian TimeCourse Model for Functional Magnetic Resonance Imaging Data  

E-print Network

A Bayesian Time­Course Model for Functional Magnetic Resonance Imaging Data Christopher R. Genovese Functional Magnetic Resonance Imaging (fMRI) is a new technique for studying the workings of the active human brain. During an fMRI ex­ periment, a sequence of Magnetic Resonance images is acquired while a subject

Genovese, Christopher

446

Giant resonance decay  

SciTech Connect

Decay studies of giant multipole resonances are discussed, emphasizing the role of Coulomb excitation with intermediate energy heavy ions, which can provide very large cross sections for both isoscalar and isovector resonances. We discuss measurement of the photon decay of one and two phonon giant resonances, reporting results where available. It is pointed out throughout the presentation that the use of E1 photons as a tag'' provides a means to observe weakly excited resonances that cannot be observed in the singles spectra. 30 refs., 16 figs., 1 tab.

Beene, J.R.; Bertrand, F.E.

1990-01-01

447

Spread spectrum magnetic resonance imaging  

E-print Network

We propose a novel compressed sensing technique to accelerate the magnetic resonance imaging (MRI) acquisition process. The method, coined spread spectrum MRI or simply s2MRI, consists of pre-modulating the signal of interest by a linear chirp before random k-space under-sampling, and then reconstructing the signal with non-linear algorithms that promote sparsity. The effectiveness of the procedure is theoretically underpinned by the optimization of the coherence between the sparsity and sensing bases. The proposed technique is thoroughly studied by means of numerical simulations, as well as phantom and in vivo experiments on a 7T scanner. Our results suggest that s2MRI performs better than state-of-the-art variable density k-space under-sampling approaches

Puy, Gilles; Gruetter, Rolf; Thiran, Jean-Philippe; Van De Ville, Dimitri; Vandergheynst, Pierre; Wiaux, Yves; 10.1109/TMI.2011.2173698

2012-01-01

448

Magnetic resonance elastography of abdomen.  

PubMed

Many diseases cause substantial changes in the mechanical properties of tissue, and this provides motivation for developing methods to noninvasively assess the stiffness of tissue using imaging technology. Magnetic resonance elastography (MRE) has emerged as a versatile MRI-based technique, based on direct visualization of propagating shear waves in the tissues. The most established clinical application of MRE in the abdomen is in chronic liver disease. MRE is currently regarded as the most accurate noninvasive technique for detection and staging of liver fibrosis. Increasing experience and ongoing research is leading to exploration of applications in other abdominal organs. In this review article, the current use of MRE in liver disease and the potential future applications of this technology in other parts of the abdomen are surveyed. PMID:25488346

Venkatesh, Sudhakar Kundapur; Ehman, Richard L

2015-04-01

449

Beams in Resonators  

NASA Astrophysics Data System (ADS)

The evolution of the main parameters (spot size, radius of curvature, far-field divergence and/or beam quality factor) of laser radiation pulses propagating in stable and unstable cavities with variable reflectivity mirrors is investigated both theoretically and experimentally as a function of the number of round trips. It is shown that a theoretical analysis, formerly developed to study the growth of coherence of a Schell-Gauss model beam propagating through a periodic sequence of Gaussian apertures, provides a satisfactory description of the laser radiation temporal evolution. The study of transient states is very important in practice because high-gain, short-pulse lasers as excimers or copper-vapor lasers, generate pulses making only a few transits inside the resonator. In this situation, beam parameters seldom reach a steady state hence, an analysis yielding the beam parameters at each round-trip is needed for a better characterization of the laser beam quality and can be of great interest in many application fields. The experimental techniques used to analyze the temporal evolution of the main parameters of laser radiation pulses few ten of nanoseconds long are at first presented. Then, the propagation of laser radiation pulses in plane-parallel cavities with a variable reflectivity mirror is analyzed. Mirrors with Gaussian, super-Gaussian and step-reflectivity profile are tested in order to investigate the effects of the mirror reflectivity profile on the temporal evolution of the laser radiation parameters. Gaussian reflectivity mirrors of different spot size E are also considered to investigate the effect of E on the radiation beam-quality-factor evolution. An experimental study of coherence evolution versus the Fresnel number of Gaussian cavities is also presented. To this end, plane parallel cavities of different length and with a Gaussian reflectivity mirror have been applied to a XeCl excimer laser (?=308 nm) and the results on the resonator-length effects on the coherence growth of the laser radiation are presented. It is also shown that in Gaussian cavities of equal length and effective Fresnel number, the properties of the intracavity radiation are dependent on the Gaussian mirror distance from the active medium, since the onset of laser action. Finally, experimental and numerical results on the beam quality and coherence growth of the laser radiation in unstable cavities equipped with a variable reflectivity mirror as output coupler are presented. Variable reflectivity unstable cavities are generally applied to pulsed laser to get a faster coherence growth of the oscillating radiation. Note from Publisher: This article contains the abstract only.

Perrone, Maria Rita

2004-08-01

450

Advances in cardiac magnetic resonance imaging of congenital heart disease.  

PubMed

Due to advances in cardiac surgery, survival of patients with congenital heart disease has increased considerably during the past decades. Many of these patients require repeated cardiovascular magnetic resonance imaging to assess cardiac anatomy and function. In the past decade, technological advances have enabled faster and more robust cardiovascular magnetic resonance with improved image quality and spatial as well as temporal resolution. This review aims to provide an overview of advances in cardiovascular magnetic resonance hardware and acquisition techniques relevant to both pediatric and adult patients with congenital heart disease and discusses the techniques used to assess function, anatomy, flow and tissue characterization. PMID:25552386

Driessen, Mieke M P; Breur, Johannes M P J; Budde, Ricardo P J; van Oorschot, Joep W M; van Kimmenade, Roland R J; Sieswerda, Gertjan Tj; Meijboom, Folkert J; Leiner, Tim

2015-01-01

451

Medical imaging techniques: implications for nursing care.  

PubMed

The four basic techniques of medical imaging are X-ray, ultrasound, magnetic resonance and radionuclide. This article describes imaging techniques that display anatomical structure and those that are better at showing the physiological function of organs and tissues. Safety and preparation relating to nursing practice are discussed. Understanding the purpose and limitations of the different imaging techniques is imp