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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, M. L.; Yesinowski, J. P.; Miller, J. B.; Krauss, Ronald A.

1994-10-01

2

Enhancing nuclear quadrupole resonance (NQR) signature detection leveraging interference suppression algorithms  

NASA Astrophysics Data System (ADS)

Nuclear quadrupole resonance (NQR) is a radio frequency (RF) magnetic spectroscopic technique that has been shown to detect and identify a wide range of explosive materials containing quadrupolar nuclei. The NQR response signal provides a unique signature of the material of interest. The signal is, however, very weak and can be masked by non-stationary RF interference (RFI) and thermal noise, limiting detection distance. In this paper, we investigate the bounds on the NQR detection range for ammonium nitrate. We leverage a low-cost RFI data acquisition system composed of inexpensive B-field sensing and commercial-off-the-shelf (COTS) software-defined radios (SDR). Using collected data as RFI reference signals, we apply adaptive filtering algorithms to mitigate RFI and enable NQR detection techniques to approach theoretical range bounds in tactical environments.

DeBardelaben, James A.; Miller, Jeremy K.; Myrick, Wilbur L.; Miller, Joel B.; Gilbreath, G. Charmaine; Bajramaj, Blerta

2012-05-01

3

INSTRUMENTS AND METHODS OF INVESTIGATION: New technologies: nuclear quadrupole resonance as an explosive and narcotic detection technique  

NASA Astrophysics Data System (ADS)

Possibilities of detecting nuclear quadrupole resonance (NQR) signals in explosives and drugs are considered. Direct and indirect NQR techniques for searching substances are described and the potentialities of various experimental methods are compared.

Grechishkin, Vadim S.; Sinyavskii, Nikolai Ya

1997-04-01

4

Structureactivity study of thiazides by magnetic resonance methods (NQR, NMR, EPR) and DFT calculations  

Microsoft Academic Search

The paper presents a comprehensive analysis of the relationship between the electronic structure of thiazides and their biological activity. The compounds of interest were studied in solid state by the resonance methods nuclear quadrupole resonance (NQR), nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) and quantum chemistry (ab inito and DFT) methods. Detailed parallel analysis of the spectroscopic parameters

J. N. Latosi?ska

2005-01-01

5

In-Situ Real Time Detection of Explosive/Chemical Compounds in Mines Using Nuclear Quadrupole Resonance (NQR).  

National Technical Information Service (NTIS)

This program was part of DARPA's 'Dog Nose' initiative to develop land mine detection technology based upon the chemical signature of the mine explosive charge. Nuclear quadrupole resonance (NQR) was the only technology pursued that detects the bulk explo...

A. D. Hibbs

2001-01-01

6

A correlation of spectroscopic parameters from different magnetic resonance spectroscopies for thiazides: a study by NQR, NMR, EPR and DFT methods  

Microsoft Academic Search

A Letter is devoted to a detailed parallel analysis of the spectroscopic parameters such as quadrupole coupling constant (NQR), chemical shift, chemical shift anisotropy, asymmetry parameter (NMR) and hyperfine coupling constant (EPR) for thiazides. The compounds were studied in solid state by the resonance (NQR, NMR and EPR) and density functional theory (DFT) methods. The spectroscopic parameters determined at room

J. N. Latosi?ska

2004-01-01

7

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

8

Quadrupole coupling parameters and structural aspects of crystalline and amorphous solids by NMR and NQR  

SciTech Connect

NMR and NQR techniques were combined to obtain the quadrupole coupling constant (Qcc) and asymmetry parameter ({eta}) and extract structural information for several borate, gallate, and metavanadate compounds and glasses. {sup 71}Ga and {sup 69}Ga NMR was used to study crystalline {beta}-Ga{sub 2}O{sub 3} and several gallate glasses. Quadrupole parameters were acquired for GaO{sub 6} and GaO{sub 4} units in {beta}-Ga{sub 2}O{sub 3} by the computer simulation of the NMR powder patterns. A sensitive CW NQR spectrometer was built to detect NQR resonances below 2 MHz. The spectrometer includes a modified Robinson oscillator-detector, a new bi-symmetric square wave Zeeman modulator and a computerized data acquisition system. {sup 51}V (I = 7/2) NQR resonances below 850 kHz were detected for several metavanadates at both room temperature and liquid nitrogen temperature. Two methods, Zeeman perturbed NQR powder pattern and {sup 10}B NQR, can be employed to obtain both Qcc and {eta}. With a double coil tank circuit design, pure {sup 11}B NQR was used to determine the fraction of borons in BO{sub 3} and BO{sub 4} configurations in hydrated zinc borates. {sup 11}B NMR and NQR were also used to study lead borate glasses.

Mao, Degen.

1991-01-01

9

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 CCl in more than 20 clathrates have been measured in the range 4-200 K. The crystal structures of CCl\\/Dianin's compound (1), CCl\\/Fe(AcAc) (3), CCl\\/Ni(SCN)(3-MePy) (4), and CCl\\/Ni(exan)(4,4-dm-2,2-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

10

Quadrupole Coupling Parameters and Structural Aspects of Crystalline and Amorphous Solids by NMR and Nqr.  

NASA Astrophysics Data System (ADS)

Nuclear quadrupole interaction is very sensitive to the local electron distribution and chemical bondings. NMR and NQR techniques have been combined to obtain the quadrupole coupling constant ({Qcc}) and asymmetry parameter (eta) and extract structural information for several borate, gallate, and metavanadate compounds and glasses. ^{71}Ga and ^{69}Ga NMR has been used to study crystalline beta-Ga _2O_3 and several gallate glasses. Quadrupole parameters were acquired for GaO_6 and GaO_4 units in beta-Ga_2 O_3 by the computer simulation of the NMR powder patterns. A sensitive CW NQR spectrometer was built to detect NQR resonances below 2 MHz. The spectrometer includes a modified Robinson oscillator-detector, a new bi-symmetric square wave Zeeman modulator and a computerized data acquisition system. ^{51}V (I = 7/2) NQR resonances below 850 kHz have been detected for several metavanadates at both room temperature and liquid nitrogen temperature. Quadrupole parameters thus obtained are an order of magnitude more accurate than values obtained by previous NMR studies. For a spin 3/2 nucleus, the pure NQR frequency {Q_{cc}over 2}sqrt{1+{eta^2over 3}}is insufficient to determine either Q_{cc} or eta. However, two methods, Zeeman perturbed NQR powder pattern and ^{10}B NQR, can be employed to obtain both Q_{cc } and eta. An example is given for ^{11}B in CaO-B_2O_3. With a double coil tank circuit design, pure ^ {11}B NQR was used to determine the fraction of borons in BO_3 and BO _4 configurations in hydrated zinc borates. ^{11}B NMR and NQR were also used to study lead borate glasses. Small changes in Q_{cc} (less than 2%) and eta (less than 0.1) suggest that BO_3 units with non-bridging oxygens are not present in the lead borate glasses.

Mao, Degen

11

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

Microsoft Academic Search

A discussion of how stress and strain affect the quantities which can be measured in an NQR experiment shows that, for stresses of the magnitude to be expected at depths up to about 10,000 feet, quadrupole coupling constants will fall in the range of 1 to 10 kHz for both the sodium and chloride ions in NaCl. The most promising

E. Schempp; T. Hirschfeld; S. Klainer

1980-01-01

12

Signal processing for NQR discrimination of buried land mines  

NASA Astrophysics Data System (ADS)

Nuclear quadrupole resonance (NQR) is a technique that discriminates mines from clutter by exploiting unique properties of explosives, rather than the attributes of the mine that exist in many forms of anthropic clutter. After exciting the explosive with a properly designed electromagnetic-induction (EMI) system, one attempts to sense late-time spin echoes, which are characterized by radiation at particular frequencies. It is this narrow-band radiation that indicates the presence of explosives, since this effect is not seen in most clutter, both natural and anthropic. However, this problem is complicated by several issues. First, the late-time radiation if often very weak, particularly for TNT, and therefore the signal-to-noise ratio must be high for extracting the NQR response. Further, the frequency at which the explosive radiates is often a strong function of the background environment, and therefore in practice the NQR radiation frequency is not known a priori. Finally, at the frequencies of interest, there is a significant amount of background radiation, which induces radio frequency interference (RFI). In this paper we discuss several signal processing tools we have developed to enhance the utility of NQR explosives detection. In particular, with regard to the RFI, we exposure least-mean-squares algorithms which have proven well suited to extracting background interference. Algorithm performance is assessed through consideration of actual measured data. With regard to the detection of the NQR electromagnetic echo, we consider a Bayesian discrimination algorithm. The performance of the Bayesian algorithm is presented, again using measured NQR data.

Tantum, Stacy L.; Collins, Leslie M.; Carin, Lawrence; Gorodnitsky, Irina; Hibbs, Andrew D.; Walsh, David O.; Barrall, Geoffrey A.; Gregory, Dave; Matthews, Robert; Vierkoetter, Stephie A.

1999-08-01

13

NQR investigation and characterization of cocrystals and crystal polymorphs  

NASA Astrophysics Data System (ADS)

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

Seliger, Janez; agar, Veselko; Asaji, Tetsuo

2013-05-01

14

Study of local magnetic fields in the oxide ?-Bi 2 O 3 by NQR and ? SR techniques  

Microsoft Academic Search

NQR and?SR investigations of the local magnetic field in?-Bi2O3 were performed. In theNQR experiments on?-Bi2O3 which is usually considered as diamagnetic, the splitting of the spectral lines revealed a local field on the bismuth nuclei. The internal magnetic field obtained by?SR significantly exceeds the dipole field from Bi nuclear magnetic moments. A possible source of the local magnetic fields is

V. N. Duginov; V. G. Grebinnik; T. N. Mamedov; V. G. Olshevsky; V. Yu. Pomjakushin; V. A. Zhukov; B. F. Kirillov; B. A. Nikolsky; V. G. Orlov; A. V. Pirogov; A. N. Ponomarev; V. A. Suetin; E. A. Kravchenko

1994-01-01

15

Factors affecting the NQR line width in nitramine explosives  

Microsoft Academic Search

A number of factors associated with crystal quality contribute to the nuclear quadrupole resonance (NQR) line width. Imperfections\\u000a such as dislocations, voids, strain and impurities can be electrical sources that distort the electric field gradient at nearby\\u000a quadrupolar nuclei and broaden the observed NQR line. We measured the14N NQR line widths in powdered samples of the nitramine explosives hexahydro-1,3,5-trinitro-s-triazine (RDX),

M. L. Buess; S. M. Caulder

2004-01-01

16

Land mine detection by nuclear quadrupole resonance  

NASA Astrophysics Data System (ADS)

Nuclear Quadrupole Resonance (NQR) combines the compound specific detection capability offered by chemical detection techniques with the spatial localization capability and convenience of an induction coil metal detector. In the 16 years since NQR was last applied to mine detection in the U.S., there has been considerable improvement in the basic techniques. This paper reviews the progress achieved under a recent initiative to detect landmines by NQR. Two basic technical developments are summarized: the design of a detection coil suitable for probing the ground for landmines buried at typical depths, and an increase in the NQR signal obtained from the explosive TNT. In addition, we report the sensitivity of an NQR detection system to detect the electromagnetic response of metal-cased landmines.

Hibbs, Andrew D.; Barrall, Geoffrey A.; Czipott, Peter V.; Lathrop, Daniel K.; Lee, Y. K.; Magnuson, Erik E.; Matthews, Robert; Vierkoetter, S. A.

1998-09-01

17

Application of a dc SQUID to rf amplification: NQR  

SciTech Connect

Superconducting QUantum Interference Devices (SQUIDs) have been used for more than a decade for the detection of magnetic resonance. Until recently, these devices had mostly been confined to operation in the audiofrequency range, so that experiments have been restricted to measurements of resonance at low frequencies, or of changes in the static susceptibility of a sample induced by rf irradiation at the resonant frequency. However, the recent extension of the operating range of low noise dc SQUIDs to radiofrequencies (rf) allows one to detect magnetic resonance directly at frequencies up to several hundred megahertz. In this paper, we begin by summarizing the properties of dc SQUIDs as tuned rf amplifers. We then describe first, the development of a SQUID system for the detection of pulsed nuclear quadrupole resonance (NQR) at about 30 MHz and second, a novel technique for observing magnetic resonances in the absence of any externally applied rf fields.

Hilbert, C.; Clarke, J.; Sleator, T.; Hahn, E.L.

1985-05-01

18

SQUID detected NMR and NQR. Superconducting Quantum Interference Device.  

PubMed

The dc Superconducting QUantum Interference Device (SQUID) is a sensitive detector of magnetic flux, with a typical flux noise of the order 1 muphi0 Hz(-1/2) at liquid helium temperatures. Here phi0 = h/2e is the flux quantum. In our NMR or NQR spectrometer, a niobium wire coil wrapped around the sample is coupled to a thin film superconducting coil deposited on the SQUID to form a flux transformer. With this untuned input circuit the SQUID measures the flux, rather than the rate of change of flux, and thus retains its high sensitivity down to arbitrarily low frequencies. This feature is exploited in a cw spectrometer that monitors the change in the static magnetization of a sample induced by radio frequency irradiation. Examples of this technique are the detection of NQR in 27Al in sapphire and 11B in boron nitride, and a level crossing technique to enhance the signal of 14N in peptides. Research is now focused on a SQUID-based spectrometer for pulsed NQR and NMR, which has a bandwidth of 0-5 MHz. This spectrometer is used with spin-echo techniques to measure the NQR longitudinal and transverse relaxation times of 14N in NH4ClO4, 63+/-6 ms and 22+/-2 ms, respectively. With the aid of two-frequency pulses to excite the 359 kHz and 714 kHz resonances in ruby simultaneously, it is possible to obtain a two-dimensional NQR spectrum. As a third example, the pulsed spectrometer is used to study NMR spectrum of 129Xe after polariza-tion with optically pumped Rb. The NMR line can be detected at frequencies as low as 200 Hz. At fields below about 2 mT the longitudinal relaxation time saturates at about 2000 s. Two recent experiments in other laboratories have extended these pulsed NMR techniques to higher temperatures and smaller samples. In the first, images were obtained of mineral oil floating on water at room temperature. In the second, a SQUID configured as a thin film gradiometer was used to detect NMR in a 50 microm particle of 195Pt at 6 mT and 4.2 K. PMID:9650797

Augustine, M P; TonThat, D M; Clarke, J

1998-03-01

19

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

PubMed

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

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

2013-05-14

20

14 N NQR spectra of complexes between hexamethylenetetramine and the crystalline hydrates of salts  

Microsoft Academic Search

Nuclear quadrupole resonance has recently been used more and more effective along with such traditional methods as vibrational spectroscopy and proton magnetic resonance to investigate hydrogen bonding. The NQR method on 14N nuclei has been put into practice at a later date than on the chlorine nuclei. This is explained by the low intensity of the 14N NQR signals and

. O. Azizov; V. S. Grechishkin; T. G. Balicheva; I. V. Pologikh

1979-01-01

21

Ressonancia de quadrupolo nuclear da arsenolita. (Nuclear quadrupole resonance of arsenolite).  

National Technical Information Service (NTIS)

A pulsed Nuclear Quadrupole Resonance (NQR) spectrometer was constructed using imported Matec units. Peripherical components were specially assembled and tested for the implantation of the spin-echo technique in the Laboratorio de Centros de Cor of IFUSP....

R. Madarazo

1988-01-01

22

Study of local magnetic fields in the oxide alpha-Bi2O3 by NQR and muSR techniques  

Microsoft Academic Search

NQR and muSR investigations of the local magnetic field in alpha-Bi2O3 were performed. In the NQR experiments on alpha-Bi2O3 which is usually considered as diamagnetic, the splitting of the spectral lines revealed a local field on the bismuth nuclei. The internal magnetic field obtained by muSR significantly exceeds the dipole field from Bi nuclear magnetic moments. A possible source of

V. N. Duginov; V. G. Grebinnik; T. N. Mamedov; V. G. Olshevsky; V. Yu. Pomjakushin; V. A. Zhukov; B. F. Kirillov; B. A. Nikolsky; V. G. Orlov; A. V. Pirogov; A. N. Ponomarev; V. A. Suetin; E. A. Kravchenko

1994-01-01

23

Semiempirical quantum mechanical calculations of electronic distribution and NQR parameters of bromine atoms in some organic and inorganic compounds  

Microsoft Academic Search

The Br electric field gradient (EFG) for some organic and inorganic compounds was calculated using a semi-empirical method. The nuclear quadrupole resonance (NQR) frequencies and asymmetry parameters of the bromine atoms in these compounds have also been evaluated. Quantitative correlation of the NQR frequencies and asymmetry parameters of the EFG of bromine nuclei with the population of p orbitals of

N. L Hadipour; S Javadian

2000-01-01

24

Radio-frequency tunable atomic magnetometer for detection of solid-state NQR  

NASA Astrophysics Data System (ADS)

We constructed a potassium atomic magnetometer which resonantly detects rf magnetic fields with subfemtotesla sensitivity. The resonance frequency is set by the Zeeman resonance of the potassium atoms in a static magnetic field applied to the magnetometer cell. Strong optical pumping of the potassium atoms into a stretched state reduces spin-exchange broadening of the Zeeman resonance, resulting in relatively small linewidth of about 200 Hz (half-width at half-maximum). The magnetometer was used to detect ^14N NQR signal from powdered ammonium nitrate at 423 kHz, with sensitivity an order of magnitude higher than with a conventional room temperature pickup coil with comparable geometry. The demonstrated sensitivity of 0.24 fT/Hz^1/2 can be improved by several means, including use of higher power lasers for pumping and probing. Our technique can potentially be used to develop a mobile, open-access NQR spectrometer for detection of nitrogen-containing solids of interest in security applications.

Lee, S.-K.; Sauer, K. L.; Seltzer, S. J.; Alem, O.; Romalis, M. V.

2007-06-01

25

Sb NQR in filled skutterudites MFe 4Sb 12 (M=Na, Ca, La)  

Microsoft Academic Search

Temperature-dependent nuclear quadrupole resonance (NQR) investigations on the 121,123Sb nuclei in filled skutterudites MFe4Sb12 (M=Na, Ca, La) are reported. These new compounds show a nice interplay of ferromagnetic and antiferromagnetic correlations best seen in the relaxation rate. Substructures observed in the 121,123Sb NQR spectra give strong evidence for static (or dynamic) disorder on the filler site. Therefore, we performed ab-initio

A. A. Gippius; E. N. Morozova; K. S. Okhotnikov; E. A. Alkaev; A. V. Shevelkov; M. Baenitz; A. Leithe-Jasper; H. Rosner; R. Viennois; Yu. Grin; F. Steglich

2006-01-01

26

Antiferromagnetic properties of a water-vapor-inserted YBa2 Cu3 O6.5 compound studied byNMR, NQR, and muSR  

Microsoft Academic Search

We present a detailed NQR, nuclear magnetic resonance (NMR), and muSR study of the magnetic phase obtained during a topotactic chemical reaction of YBa2Cu3O6.5 high-temperature superconductor with low-pressure water vapor. Cu65 -enriched samples have been used for NQR\\/NMR studies which allows to get a good resolution in the Cu(1) NQR and Cu(2) zero field NMR (ZFNMR) spectra. It is shown

A. V. Dooglav; A. V. Egorov; I. R. Mukhamedshin; A. V. Savinkov; H. Alloul; J. Bobroff; W. A. Macfarlane; P. Mendels; G. Collin; N. Blanchard; P. G. Picard; P. J. C. King; J. Lord

2004-01-01

27

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

28

Determination of the electric field gradient tensor by 2D NQR  

Microsoft Academic Search

For a full specification of the Electric Field Gradient (EFG) tensor, five independent parameters are necessary: the asymmetry parameter (?), the largest component of the EFG (eq), and three angles which determine the orientation of the EFG principal axis with respect to the crystallographic frame. The parameters eq and ? can be determined independently by pure Nuclear Quadrupole Resonance (NQR)

C. R. Hernn; S. R. Rabbani; Christovam Mendona

1997-01-01

29

APPLICATION OF OPTIMIZATION TECHNIQUES FOR ACOUSTICAL RESONATORS  

Microsoft Academic Search

Abstract Following our preceding work ,on the ,optimization of structural vibrating components ,of musical instruments, we now have extended those techniques to acoustical resonators for marimba-type,instruments or other ,applications. In this paper we suggest ,that acoustical resonators may be tuned to multiple modes of the vibrating bars, in order to enrich or simply modify the timbre of the instrument. After

Lus Henrique; Jos Antunes; Octvio Incio; Jos Paulino

30

Evidence of Antiferromagnetic Ordering in La/sub 2/CuO/sub 4/: Re-Interpretation of /sup 139/La Nuclear Quadrupole Resonance (NQR) Data.  

National Technical Information Service (NTIS)

A re-interpretation of the result of recent /sup 139/La nuclear quadrupole resonance measurements on La/sub 2/CuO/sub 4/ reveals an antiferromagnetic order in this material at low temperature. The magnitude and the direction of the local field at the La p...

I. Furo A. Janossy

1987-01-01

31

Other magnetic resonance imaging techniques.  

PubMed

Relatively new developments in MRI, such as functional MRI (fMRI), magnetic resonance spectroscopy (MRS) and diffusion tensor imaging (DTI) are rapidly developing into imaging modalities that will become clinically available in the near future. They have in common that their signal is somewhat easier to interpret than structural MRI: fMRI mirrors excess cerebral blood flow, in many cases representing brain activity, MRS gives the average volume concentrations of specific chemical compounds, and DTI reflects "directedness" of micro-anatomical structures, of particular use in white matter where fiber bundle disruption can be detected with great sensitivity. While structural changes in MRI have been disappointing in giving a diagnosis of sufficient sensitivity and specificity, these newer methods hold out hope for elucidating pathological changes and differentiating patient groups more rigorously. This paper summarizes promising research results that will yet have to be translated into real life clinical studies in larger groups of patients (e.g. memory clinic patients). Where available, we have tried to summarize results comparing different types of dementia. PMID:21843379

Ebmeier, Klaus P; Filippini, Nicola; Heise, Verena; Sexton, Claire E

2011-09-01

32

Nuclear quadrupole resonance single-pulse echoes.  

PubMed

We report the first detection of a spin echo after excitation of a powder sample by a single pulse at the resonance frequency during nuclear quadrupole resonance (NQR). These echoes can occur in samples that have an inhomogeneously broadened line, in this case due to the distribution of electric field gradients. The echoes are easily detectable when the Rabi frequency approaches the linewidth and the average effective tipping angle is close to 270 degrees. When limited by a weak radio-frequency field, the single-pulse echo can be used to increase the signal to noise ratio over conventional techniques. These effects can be used to optimize the NQR detection of contraband containing quadrupole nuclei and they are demonstrated with glycine hemihydrochloride and hexhydro-1,3,5-trinitro-1,3,5-triazine (RDX). PMID:18571445

Prescott, David W; Miller, Joel B; Tourigny, Chris; Sauer, Karen L

2008-05-29

33

Nuclear quadrupole resonance: a technique to control hydration processes in the pharmaceutical industry.  

PubMed

Pharmaceuticals can exist in many solid forms, which can have different physical and chemical properties. These solid forms include polymorphs, solvates, amorphous, and hydrates. Particularly, hydration process can be quite common since pharmaceutical solids can be in contact with water during manufacturing process and can also be exposed to water during storage. In the present work, it is proved that NQR technique is capable of detecting different hydrated forms not only in the pure raw material but also in the final product (tablets), being in this way a useful technique for quality control. This technique was also used to study the dehydration process from pentahydrate to trihydrate. PMID:21314133

Limandri, Silvina; Visovezky, Claudia; Prez, Silvina C; Schurrer, Clemar A; Wolfenson, Alberto E; Ferro, Maribel; Cuffini, Silvia L; de Souza, Joel Gonalves; Aguiar, F Armani; de Gaitani, C Masetto

2011-02-11

34

Electromagnetic contactless interrogation technique for quartz resonator sensors  

Microsoft Academic Search

A technique for contactless readout of AT-cut quartz resonator sensors is proposed and validated. The technique is based on the separation in time of the excitation and detection phases, exploiting the sensing of the transient response of the resonator. An external primary coil is electromagnetically air-coupled to a secondary coil connected to the electrodes of the resonator. During the excitation

M. Bau; M. Ferrari; V. Ferrari; E. Tonoli

2011-01-01

35

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.; agar, V.; Kazimierczuk, Z.

2009-07-01

36

Mode Shape Measurement of Piezoelectric Resonators Using Image Processing Technique  

Microsoft Academic Search

An image processing technique for measuring the mode shapes of piezoelectric resonators is described. Laser speckle interference, a periodic resonator excitation and charge coupled device (CCD) image captures are effectively combined in this method. The experimental results for three kinds of AT-cut quartz resonators demonstrate the applicability of the proposed method.

Yasuaki Watanabe; Yuji Shikama; Shigeyoshi Goka; Takayuki Sato; Hitoshi Sekimoto

2001-01-01

37

NDI using mm-wave resonant techniques  

NASA Astrophysics Data System (ADS)

Millimeter wave resonant measurements are commonly used for surface and near-surface materials characterization including the detection of cracks and defects, analysis of semiconducting and dielectric materials, and analysis of metallic electrical properties beneath coatings. Recent work has also shown the approach to be useful in evaluating corrosion products and the detection of incipient corrosion and corrosion cracking. In the analysis area, complex permittivity data of the corrosion products can be extracted, usually with accuracy of a few percent or better, to aid in identification of the product and possibly of mechanisms. In the detection area, corrosion-related cracks of order 100 microns or less near the surface have been detected and corrosion products have been detected beneath a variety of paints. Surface preparation requirements are minimal, particularly compared to some optical techniques, giving increased hope of field applicability. A number of examples of NDI on aircraft related materials and structures will be presented along with an assessment of detection and accuracy limits.

Martens, J. S.; Sachtjen, S.; Sorensen, N. R.

1995-08-01

38

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

39

Electronic structure and biological activity of chosen DDT-type insecticides studied by 35Cl-NQR.  

PubMed

A correlation between the electronic structure and biological activity of chosen dichlorodiphenyltrichloroethane (DDT)-type insecticides: 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane, 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane, 2,2-bis(p-chlorophenyl)-1,1-dichloroethylene, 2,2-bis(4-chlorophenyl)ethanoic acid and 4,4'-dichlorobenzophenone (used in agriculture) has been analysed on the basis of the (35)Cl-nuclear quadrupole resonance (NQR) spectroscopy. The (35)Cl-NQR resonance frequencies measured at 77 K have been correlated with the lethal dose (LD(50)) parameter that characterises the biological activity of these insecticides. PMID:18942076

Jadzyn, Maciej; Nogaj, Boles?aw

2009-02-01

40

Overcurrent protection control technique of ZCS series resonant rectifier  

Microsoft Academic Search

An overcurrent protection control technique for a zero current switched (ZCS) series resonant rectifier (SRR) is proposed. With the proposed control technique, the converter can operate in the safe region, and optimum rating devices can be used. By employing zero current switching operations for all switches, the series resonant rectifier can operate at high switching frequencies and high power levels.

Young Seok Jung; Jong Sun Ko; Gun Woo Moon; Myung Joong Youn

1995-01-01

41

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

PubMed

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

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

2008-02-01

42

An optical phase amplification technique for interrogating fiber resonator sensors  

Microsoft Academic Search

We describe a technique for the effective amplification of small phase changes induced by cavity perturbations of a resonant fiber-optic sensor. The scheme utilizes an unbalanced two-beam read-out interferometer to monitor weak frequency shifts in a laser source locked to the resonant sensor. Results are presented using a fiber ring resonator sensor and Mach-Zehnder read-out interferometer with a system phase

K. P. Koo; A. D. Kersey

1995-01-01

43

Optical phase amplification technique for interrogating fiber resonator sensors  

Microsoft Academic Search

We describe a technique for the effective amplification of small phase changes induced by cavity perturbations of a resonant fiber-optic sensor. The scheme utilizes an unbalanced two-beam 'read-out' interferometer to monitor weak frequency shifts in a laser source locked to the resonant sensor. Results are presented using a fiber ring resonator sensor and Mach-Zehnder read-out interferometer with a system phase

K. P. Koo; A. D. Kersey

1995-01-01

44

A Resonant Frequency Tracking Technique for Linear Vapor Compressors  

Microsoft Academic Search

A linear vapor compressor operates most efficiently at resonant frequency which varies with piston stroke and operation conditions. A novel resonant frequency tracking technique is proposed in order to achieve high efficiency operation of a linear compressor system. This is based on the fact that for given amplitude of the motor current, the linear compressor system reaches its maximum stroke

Zhengyu Lin; Jiabin Wang; D. Howe

2007-01-01

45

Sb NQR study of the filled skutterudite CeFe4Sb12 synthesized under high pressure  

NASA Astrophysics Data System (ADS)

We report the results of Sb nuclear quadrupole resonance (NQR) measurements on the filled skutterudite CeFe4Sb12 synthesized under high pressure (HP) and compare them with those for the sample synthesized under ambient pressure (AP) to understand the influence of the Ce-site filling fraction. The NQR spectra for the HP sample are much sharper than those for the AP sample, suggesting that the Ce filling fraction is higher. Also, the nuclear spin-lattice relaxation rate 1/ T 1 follows an exponential decrease 1/ T 1 ? exp(-?/ k B T), with the gap being ?/ k B = 270 K at temperatures above 100 K, which is larger than that for the AP sample. This result suggests that the c- f hybridization is enhanced by increasing the Ce-site filling fraction.

Magishi, Ko-ichi; Takahashi, Masahiro; Saito, Takahito; Koyama, Kuniyuki; Sugawara, Hitoshi; Saito, Takashi; Tatsuoka, Sho; Tanaka, Kenya; Sato, Hideyuki

2013-08-01

46

Detection of TNT and RDX landmines by standoff nuclear quadrupole resonance  

NASA Astrophysics Data System (ADS)

Nuclear Quadrupole Resonance (NQR) combines the compound specific detection capability offered by chemical offered by chemical detection techniques with the spatial coating capability and convenience of an induction coil metal detector. In this paper we present the first results of the detection of TNT by NQR with sufficient for detection of many antipersonnel mines and essentially all antitank mines. In addition, we review the result of a blind in-field demonstration of the system in detecting RDX in which 28 out of 31 RDX-only targets were found with 1 false alarm in a 110 m test lane, and a second test in which 21 out of 21 RDX mines were found with zero false alarms at a clearance rate of 1.1 m2 per minute.

Hibbs, Andrew D.; Barrall, Geoffrey A.; Czipott, Peter V.; Drew, A. J.; Gregory, Dave; Lathrop, Daniel K.; Lee, Y. K.; Magnuson, Erik E.; Matthews, Robert; Skvoretz, D. C.; Vierkoetter, Stephie A.; Walsh, David O.

1999-08-01

47

Ab initio DFT study of bisphosphonate derivatives as a drug for inhibition of cancer: NMR and NQR parameters.  

PubMed

DFT computations were carried out to characterize the (17)Oand (2)H electric field gradient, EFG, in various bisphosphonate derivatives. The computations were performed at the B3LYP level with 6-311++G (d,P) standard basis set. Calculated EFG tensors were used to determine the (17)O and (2)H nuclear quadrupole coupling constant, ? and asymmetry parameter, ?. For better understanding of the bonding and electronic structure of bisphosphonates, isotropic and anisotropic NMR chemical shieldings were calculated for the (13)C, (17)O and (31)P nuclei using GIAO method for the optimized structure of intermediate bisphosphonates at B3LYP level of theory using 6-311++G (d, p) basis set. The results showed that various substituents have a strong effect on the nuclear quadrupole resonance (NQR) parameters (?, ?) of (17)O in contrast with (2)H NQR parameters. The NMR and NQR parameters were studied in order to find the correlation between electronic structure and the activity of the desired bisphosphonates. In addition, the effect of substitutions on the bisphosphonates polarity was investigated. Molecular polarity was determined via the DFT calculated dipole moment vectors and the results showed that substitution of bromine atom on the ring would increase the activity of bisphosphonates. PMID:21633790

Aghabozorg, Hussein; Sohrabi, Beheshteh; Mashkouri, Sara; Aghabozorg, Hamid Reza

2011-06-02

48

Co Nuclear-Quadrupole-Resonance Measurements on NaxCoO2.yH2O - Phase Diagram for Bilayered-Hydrate System  

Microsoft Academic Search

Co nuclear quadrupole resonance (NQR) measurements were performed on several superconducting (SC) NaxCoO2.yH2O samples with different values of a SC transition temperature (Tc). The measurements were done for the investigation of the relationship between Tc and microscopic physical quantities derived from the Co NQR. We measured Co-NQR frequency nuQ and the nuclear-lattice relaxation rate 1\\/T1 the Co site, and found

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

2006-01-01

49

Nuclear quadrupole resonance study of hydrogen bonded solid materials.  

PubMed

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

Seliger, Janez

2011-09-01

50

Narcotics and explosives detection by 14N pure nuclear quadrupole resonance  

NASA Astrophysics Data System (ADS)

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

Garroway, Allen N.; Buess, M. L.; Yesinowski, J. P.; Miller, J. B.

1994-03-01

51

Workshop on Siberian Snakes and depolarizing resonances correcting techniques  

SciTech Connect

Discussions during the Workshop on Siberian Snakes and Depolarizing Resonances Correcting Techniques are summarized. It has been firmly established theoretically depolarization can be avoided by means of Siberian Snakes. The results from the first experimental test are eagerly awaited.(AIP)

Roser, T. (Randall Laboratory of Physics, The University of Michigan, Ann Arbor, MI 48109 (US))

1989-05-05

52

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

53

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

Microsoft Academic Search

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

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

2005-01-01

54

Current modulation technique used in resonator micro-optic gyro.  

PubMed

Resonator micro-optic gyro (RMOG) is a promising candidate for the next generation inertial rotation sensor based on the Sagnac effect. A current modulation technique used in an external cavity laser diode is proposed to construct the gyroscope system for the first time. The resonance curves before and after eliminating accompanying amplitude modulation are theoretically analyzed, calculated, and simulated; the demodulation curves with different modulation currents are formulated theoretically; and the optimum modulation current corresponding to the maximum sensitivity is obtained. The experiment results from the established RMOG experimental setup demonstrate that a bias stability of 2.7 deg/s (10 s integrated time) over 600 s, and dynamic range of 500 deg/s are demonstrated in an RMOG with a silica optical waveguide ring resonator having a ring length of 12.8 cm. PMID:23314650

Lei, Ming; Feng, Lishuang; Zhi, Yinzhou; Liu, Huilan; Wang, Junjie; Ren, Xiaoyuan; Su, Ni

2013-01-10

55

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

56

The single NqrB and NqrC subunits in the Na(+)-translocating NADH: quinone oxidoreductase (Na(+)-NQR) from Vibrio cholerae each carry one covalently attached FMN.  

PubMed

The Na(+)-translocating NADH:quinone oxidoreductase (Na(+)-NQR) is the prototype of a novel class of flavoproteins carrying a riboflavin phosphate bound to serine or threonine by a phosphodiester bond to the ribityl side chain. This membrane-bound, respiratory complex also contains one non-covalently bound FAD, one non-covalently bound riboflavin, ubiquinone-8 and a [2Fe-2S] cluster. Here, we report the quantitative analysis of the full set of flavin cofactors in the Na(+)-NQR and characterize the mode of linkage of the riboflavin phosphate to the membrane-bound NqrB and NqrC subunits. Release of the flavin by ?-elimination and analysis of the cofactor demonstrates that the phosphate group is attached at the 5'-position of the ribityl as in authentic FMN and that the Na(+)-NQR contains approximately 1.7mol covalently bound FMN per mol non-covalently bound FAD. Therefore, each of the single NqrB and NqrC subunits in the Na(+)-NQR carries a single FMN. Elimination of the phosphodiester bond yields a dehydro-2-aminobutyrate residue, which is modified with ?-mercaptoethanol by Michael addition. Proteolytic digestion followed by mass determination of peptide fragments reveals exclusive modification of threonine residues, which carry FMN in the native enzyme. The described reactions allow quantification and localization of the covalently attached FMNs in the Na(+)-NQR and in related proteins belonging to the Rhodobacter nitrogen fixation (RNF) family of enzymes. This article is part of a Special Issue entitled: 17th European Bioenergetics Conference (EBEC 2012). PMID:22366169

Casutt, Marco S; Schlosser, Andreas; Buckel, Wolfgang; Steuber, Julia

2012-02-16

57

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; Jelnek, Michal; Chembo, Yanne K.; Pogurmiskiy, Maxim; Tavernier, Herv; Volyanskiy, Kirill; Phan Huy, Kien; Chauvet, Mathieu; Larger, Laurent; Kubecek, Vclav

2011-05-01

58

Infrared surface plasmon resonance technique for biological studies  

NASA Astrophysics Data System (ADS)

We report on a surface plasmon resonance (SPR) technique based on Fourier-transform infrared spectrometer. In contrast to the conventional surface plasmon technique, operating at a fixed wavelength and at variable angle of incidence, our setup allows the wavelength and the angle of incidence to be varied simultaneously. We explored the potential of the SPR technique in the infrared for biological studies involving aqueous solutions. Using computer simulations, we found the optimal combination of parameters (incident angle and wavelength) for performing this task. Our experiments with physiologically important glucose concentrations in water and in human plasma verified our computer simulations. Importantly, we demonstrated that the sensitivity of the SPR technique in the infrared range is not lower and, in fact, is even higher than that for visible light. We emphasize the advantages of infrared SPR for studying glucose and other biological molecules in living cells.

Lirtsman, V.; Golosovsky, M.; Davidov, D.

2008-01-01

59

WURST-QCPMG sequence and "spin-lock" in ?N nuclear quadrupole resonance.  

PubMed

?N nuclear quadrupole resonance (NQR) is a promising method for the analysis of pharmaceuticals or for the detection of nitrogen based illicit compounds, but so far, the technique is still not widely used, mostly due to the very low sensitivity. This problem is already acute in the preliminary NQR stage, when a compound is being examined for the first time and the NQR frequencies are being searched for, by scanning a wide frequency range step-by-step. In the present work, we experimentally show how to increase the efficiency of this initial stage by using a combination of a wideband excitation achieved with frequency swept pulses (WURST) and a "spin-lock" state obtained with a quadrupolar-CPMG (QCPMG) sequence. In the first part we show that WURST pulses provide a much larger excitation bandwidth compared to common rectangular pulses. This increased bandwidth allows to increase the frequency step and reduces the total number of steps in a scanning stage. In the second part we show that the "spin-lock" decay time T2eff obtained with the WURST-QCPMG combination is practically identical with the T2eff obtained with the most common "spin-lock" sequence, the SLSE, despite a very different nature and length of excitation pulses. This allows for a substantial S/N increase through echo averaging in every individual step and really allows to exploit all the advantages of the wider excitation in the NQR frequency scanning stage. Our experimental results were obtained on a sample of trinitrotoluene, but identical behavior is expected for all compounds where a "spin-lock" state can be created. PMID:23793057

Gregorovi?, Alan; Apih, Toma

2013-06-04

60

A new characterization technique for lossy piezoceramic resonators  

NASA Astrophysics Data System (ADS)

Piezoelectricity was discovered by the brothers Curie in 1880. They found that, in certain materials such as zincblende, tourmaline, can sugar, topaz and quartz, mechanical stresses were accompanied by the production of electric surface charges. The piezoelectric effect remained a curiosity until the early 1920s when it was utilized to realize crystal resonators for the stabilization of oscillators, thereby launching the field of frequency control. Piezoelectricity has found many applications as oscillators, filters, and sensors in televisions, cellular phones, radios, ultrasonic imaging, radar and signal processing to name just a few. Most of these applications use high Q single crystal materials such as quartz. These materials can become expensive as the application becomes more specialized. Piezoceramic materials can be used in these applications because it is less expensive, but the Q of the material is low and has very blunt characteristics as compared to quartz. This low Q and blunt resonance is connected to the loss in the material and makes it difficult to characterize the material and to get the maximum performance out of devices made from this material. We have developed a new characterization technique for lossy piezoceramic material based on the use of complex frequencies to stimulate the devices complex resonant point. This technique enables us to find the frequency dependent attenuation constant, and the impedance at the complex resonant point. The material properties of piezoceramics can be described through the use of complex material constants. The solution of the acoustic wave equation leads to complex frequencies as the resonant points for a thickness excited resonator. This leads to the use of complex frequency excitation, which is an exponentially decaying sine wave. The Laplace transform of this type of signal has an imaginary part which is the frequency and the real part which is related to the attenuation of the device. So this type of signal is ideal to characterize lossy materials which can be described with complex material constants. Experimental results will be presented showcasing the complex frequency excitation technique. The attenuation constant calculations will be presented along with the variation of the impedance as a function of the attenuation constant. Modeling and simulation results using an equivalent circuit model will also be presented.

Pastore, Robert Allan, Jr.

2000-11-01

61

Electronic properties of LaO1-xFxFeAs in the normal state probed by NMR/NQR  

NASA Astrophysics Data System (ADS)

We report 139La, 57Fe and 75As nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements on powders of the new LaO1-xFxFeAs superconductor for x=0 and 0.1 at temperatures up to 480 K, and compare our measured NQR spectra with local density approximation (LDA) calculations. For all three nuclei in the x=0.1 material, it is found that the local Knight shift increases monotonically with an increase in temperature, and scales with the macroscopic susceptibility, suggesting a single magnetic degree of freedom. Surprisingly, the spin lattice relaxation rates for all nuclei also scale with one another, despite the fact that the form factors for each site sample different regions of q-space. This result suggests a lack of any q-space structure in the dynamical spin susceptibility that might be expected in the presence of antiferromagnetic correlations. Rather, our results are more compatible with simple quasi-particle scattering. Furthermore, we find that the increase in the electric field gradient at the As cannot be accounted for by LDA calculations, suggesting that structural changes, in particular the position of the As in the unit cell, dominate the NQR response.

Grafe, H.-J.; Lang, G.; Hammerath, F.; Paar, D.; Manthey, K.; Koch, K.; Rosner, H.; Curro, N. J.; Behr, G.; Werner, J.; Leps, N.; Klingeler, R.; Klauss, H.-H.; Litterst, F. J.; Bchner, B.

2009-03-01

62

Off-resonance effects and selectivity profiles in pulsed nitrogen-14 nuclear quadrupole resonance.  

PubMed

In order to alleviate base-line distortions in nitrogen-14 NQR spectra originating from pulse breakthrough, low power radio-frequency (rf) pulses were applied. It is recalled that the required power is four times lower than that for an equivalent NMR experiment. This is easily explained by the fact that, in NMR, half the amplitude of the rf field is active. Moreover, the selectivity profile (i.e. the peak amplitude as a function of the difference between the carrier frequency and the resonance frequency) exhibits a shape which is, in most cases, more favorable in NQR than in NMR. An appropriate theory has been developed for explaining these experimental observations. It is concluded that low power NQR is perfectly feasible and should even be recommended for most applications, provided that the line-width of the NQR signal is not too large. PMID:23063174

Guendouz, L; Robert, A; Retournard, A; Leclerc, S; Aissani, S; Canet, D

2012-09-01

63

NQR spin-echo methods at very low temperatures  

NASA Astrophysics Data System (ADS)

Pulsed methods may be successfully used in very low temperature NMR or NQR experiments provided good thermal anchoring of the sample is achieved. In order to reduce heating effects, it is advantageous to use rf pulses that are shorter than the standard magnetization tipping pulses used at higher temperatures. The present work describes the use of short nonstandard rf pulses in NQR spin-echo experiments on powdered samples. Theoretical density matrix calculations have been carried out, and the resulting expression for the echo amplitude confirmed by experiment. Measurements were made on a powder sample of high-purity semimetallic arsenic using a sample probe designed for use in a dilution refrigerator. Preliminary spin-lattice relaxation-time measurements show that the Korringa relation holds in arsenic down to 150 mK.

Goudemond, I. P.; Keartland, J. M.; Hoch, M. J. R.

1991-03-01

64

Complex permittivity measurements of ferroelectrics employing composite dielectric resonator technique.  

PubMed

Composite cylindrical TE(0n1) mode dielectric resonator has been used for the complex permittivity measurements of ferroelectrics at frequency about 8.8 GHz. Rigorous equations have been derived that allowed us to find a relationship between measured resonance frequency and Q-factor and the complex permittivity. It has been shown that the choice of appropriate diameter of a sample together with rigorous complex angular frequency analysis allows precise measurements of various ferroelectric. Proposed technique can be used for materials having both real and imaginary part of permittivity as large as a few thousand. Variable temperature measurements were performed on a PbMg(1/3)Nb(2/3)O3 (PMN) ceramic sample, and the measured complex permittivity have shown good agreement with the results of measurements obtained on the same sample at lower frequencies (0.1-1.8 GHz). PMID:17036796

Krupka, Jerzy; Zychowicz, Tomasz; Bovtun, Viktor; Veljko, Sergiy

2006-10-01

65

Feasibility of nuclear quadrupole resonance as a novel dosimetry tool  

Microsoft Academic Search

Nuclear quadrupole resonance (N.Q.R) frequencies are influenced by the symmetry of the charge distribution of a compound around the site of interest. Damage by ionizing radiation causes changes in this charge symmetry which can be detected by standard pulsed N.Q.R. methods. Previous work done on various chlorates of [sup 35]Cl at room temperature (Vargas et al., 1978) shows a linear

L. H. Iselin; D. E. Hintenlang; S. J. Epperson; G. A. Higgins; K. Jamil

1990-01-01

66

Feasibility of nuclear quadrupole resonance as a novel dosimetry tool  

Microsoft Academic Search

Nuclear quadrupole resonance (N.Q.R) frequencies are influenced by the symmetry of the charge distribution of a compound around the site of interest. Damage by ionizing radiation causes changes in this charge symmetry which can be detected by standard pulsed N.Q.R. methods. Previous work done on various chlorates of ³⁵Cl at room temperature (Vargas et al., 1978) shows a linear effect

L. H. Iselin; D. E. Hintenlang; S. J. Epperson; G. A. Higgins; K. Jamil

1990-01-01

67

A new mass reconstruction technique for resonances decaying to ??  

NASA Astrophysics Data System (ADS)

Accurate reconstruction of the mass of a resonance decaying to a pair of ? leptons is challenging because of the presence of multiple neutrinos from ? decays. The existing methods rely on either a partially reconstructed mass, which has a broad spectrum that reduces sensitivity, or the collinear approximation, which is applicable only to the relatively small fraction of events. We describe a new technique, which provides an accurate mass reconstruction of the original resonance and does not suffer from the limitations of the collinear approximation. The major improvement comes from replacing assumptions of the collinear approximation by a requirement that mutual orientations of the neutrinos and other decay products are consistent with the mass and decay kinematics of a ? lepton. This is achieved by maximizing a probability defined in the kinematically allowed phase space region. In this paper we describe the technique and illustrate its performance using Z/?*??? and H??? events simulated with the realistic detector resolution. The method is also tested on a clean sample of data Z/?*??? events collected by the CDF experiment at the Tevatron. We expect that this new technique will allow for a major improvement in searches for the Higgs boson at both the LHC and the Tevatron.

Elagin, A.; Murat, P.; Pranko, A.; Safonov, A.

2011-10-01

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

Possible stripe fluctuations in La2 - x - yNdySrxCuO4 at room temperature observed by 63Cu NQR spectroscopy  

NASA Astrophysics Data System (ADS)

63Cu nuclear quadrupole resonance (NQR) studies at room temperature were reported on six Nd-doped La2 - xSrxCuO4 samples. The NQR spectrum for La1.48Nd0.4Sr0.12CuO4 has a different line shape compared with those from the other samples, which is similar to the case of the insulating La2CuO4. This may suggest that the stripe fluctuations at such a special Nd and Sr doping fall into the frequency window of 63Cu NQR. The spectra of the other five samples were analysed by pairs of 63Cu and 65Cu Gaussians at A and B sites. The full width of half-maxim (FWHM) for 63Cu at B sites is anomalously large for La1.45Nd0.4Sr0.15CuO4, which was considered to be related to the stripe fluctuations.

Zhang, Q.-M.; Ying, X. N.; Gu, M.; Wang, Y. N.

2005-04-01

70

Magnetic resonance imaging of the elbow. Part I: Normal anatomy, imaging technique, and osseous abnormalities  

Microsoft Academic Search

Part I of this comprehensive review on magnetic resonance imaging of the elbow discusses normal elbow anatomy and the technical factors involved in obtaining high-quality magnetic resonance images of the elbow. Part I also discusses the role of magnetic resonance imaging in evaluating patients with osseous abnormalities of the elbow. With proper patient positioning and imaging technique, magnetic resonance imaging

Richard Kijowski; Michael Tuite; Matthew Sanford

2004-01-01

71

NMR and NQR parameters of the SiC-doped on the (4,4) armchair single-walled BPNT: a computational study.  

PubMed

The structural properties, NMR and NQR parameters in the pristine and silicon carbide (SiC) doped boron phosphide nanotubes (BPNTs) were calculated using DFT methods (BLYP, B3LYP/6-31G) in order to evaluate the influence of SiC-doped on the (4,4) armchair BPNTs. Nuclear magnetic resonance (NMR) parameters including isotropic (CS(I)) and anisotropic (CS(A)) chemical shielding parameters for the sites of various (13)C, (29)Si, (11)B, and (31)P atoms and quadrupole coupling constant (C ( Q )), and asymmetry parameter (? ( Q )) at the sites of various (11)B nuclei were calculated in pristine and SiC- doped (4,4) armchair boron phosphide nanotubes models. The calculations indicated that doping of (11)B and (31)P atoms by C and Si atoms had a more significant influence on the calculated NMR and NQR parameters than did doping of the B and P atoms by Si and C atoms. In comparison with the pristine model, the SiC- doping in Si(P)C(B) model of the (4,4) armchair BPNTs reduces the energy gaps of the nanotubes and increases their electrical conductance. The NMR results showed that the B and P atoms which are directly bonded to the C atoms in the SiC-doped BPNTs have significant changes in the NMR parameters with respect to the B and P atoms which are directly bonded to the Si atoms in the SiC-doped BPNTs. The NQR results showed that in BPNTs, the B atoms at the edges of nanotubes play dominant roles in determining the electronic behaviors of BPNTs. Also, the NMR and NQR results detect that the Fig. 1b (Si(P)C(B)) model is a more reactive material than the pristine and the Fig. 1a (Si(B)C(p)) models of the (4,4) armchair BPNTs. PMID:21625895

Baei, Mohammad T; Sayyad-Alangi, S Zahra; Moradi, Ali Varasteh; Torabi, Parviz

2011-05-28

72

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

PubMed

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

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

2005-07-14

73

Nuclear quadrupole resonance of norephedrine.  

PubMed

Toward searching for illegal drugs, we investigated the pulsed nuclear quadrupole resonance (NQR) response of 14N in (1R,2S)-(-)-norephedrine, based on the predictions of quantum chemical calculations. Two pairs of spectral lines (?+=3.089, 3.093 MHz and ?-=2.594, 2.608 MHz) were observed despite its molecule structure having only a single nitrogen atom. This indicates that the molecular crystal has two nonequivalent nitrogen atoms in the unit cell. The temperature dependence of the NQR frequencies and relaxation properties were investigated for the purpose of accurate remote sensing of the drugs. The NQR frequency shift was approximately 0.23 kHz/K around room temperature. The spin-lattice relaxation and spin-phase memory times were 5.2-10.2 ms and 0.6-1.5 ms, respectively. PMID:21924876

Shinohara, Junichiro; Kobayashi, Kazuhiko; Sato-Akaba, Hideo; Itozaki, Hideo

2011-09-06

74

^63Cu NQR relaxation in the p-type transparent conductor CuScO_2:Mg  

NASA Astrophysics Data System (ADS)

Transparent conducting oxides with p-type conductivity are of interest as electronic complements to the more familiar n-type transparent conductors. This paper reports the first results of a study of carrier spin dynamics in p-type CuScO_2:Mg using ^63Cu nuclear spin-lattice relaxation measurements. Relaxation rates 1/T1 have been measured by nuclear quadrupole resonance (NQR) over the range 280 K to 400 K. The ^63Cu NQR frequency is found to be 28,135 5 kHz at 300 K and to decrease linearly with temperature over the experimental range. The value of 1/T1 at 300 K is 130 10 s-1. The rate is weakly dependent on temperature and increases by only about 15 % up to 400 K. This behavior contrasts sharply with results obtained previously(1. A. Rajabzadeh, J. Tate and W. Warren, Bull. Am. Phys. Soc. 48, 1009 (2003).) for the related material CuYO_2:Ca. In that material, relaxation rates for ^63Cu and ^65Cu were strongly temperature dependent, being approximately thermally-activated with activation energy 152 10 meV. The nuclear relaxation properties of CuScO_2:Mg are suggestive of more conventional metallic transport in CuScO_2:Mg compared with CuYO_2:Ca.

Rossi, Vincent; Tate, Janet; Warren, William; Li, Jun; Sleight, Arthur

2003-05-01

75

Relative Permittivity Measurement of Rectangular Copper-Laminated Substrates Using the Full-Sheet Resonance Technique.  

National Technical Information Service (NTIS)

A measurement program has been undertaken at NIST to evaluate the full-sheet resonance (FSR) technique, from which consistent relative permittivity values have been obtained. We present an analysis of the theory underlying the FSR technique, along with a ...

R. L. Lewis

1997-01-01

76

Relative Permittivity Measurement of Square Copper-Laminated Substrates Using the Full-Sheet Resonance Technique.  

National Technical Information Service (NTIS)

The full sheet resonance (FSR) technique has been available a number of years for measuring the relative permittivity of microwave circuit board substrates. A measurement program has been undertaken at NIST to evaluate this technique, and consistent value...

R. L. Lewis

1997-01-01

77

New output voltage control technique using dynamic model for quantum series resonant convertor  

NASA Astrophysics Data System (ADS)

A new output voltage control technique using deadbeat control action is proposed to improve the output voltage control performance of the quantum series resonant convertor. With this technique, the resonant current can be controlled effectively by the resonant capacitor voltage, and the ripple magnitude of the output voltage is remarkably reduced. Also, the startup transient response of the proposed controller is as fast as that of the conventional controller.

Hong, S. S.; Ko, J. H.; Cho, K. Y.; Oh, D. S.; Yoon, M. J.

1991-03-01

78

Wireless interrogation techniques for sensors utilizing inductively coupled resonance circuits  

Microsoft Academic Search

The methods needed to interrogate passive resonance sensors are studied. A portable impedance measurement unit and the methods to extract a coupling coefficient compensated resonance frequency are presented. The interrogation methods are demonstrated with ECG and pressure measurements. The results show that the quality of the ECG signal measured with a flexible textile coil is sufficient to extract the heart

Timo Salpavaara; Jarmo Verho; Pekka Kumpulainen; Jukka Lekkala

2010-01-01

79

Phonon detection technique for the study of the temperature coefficient of resonance frequency in clamped-clamped beam resonators  

NASA Astrophysics Data System (ADS)

In this paper, we utilize a phonon detection technique to determine the temperature coefficient of resonant frequency TCf of MEMS resonators. The technique adopted is highly sensitive to device motions and allows for TCf measurement with less than 5 ppm C-1 error. In addition, it can also characterize multiple resonators fabricated on the same die or wafer using a single piezoelectric element. Although the multiple devices have to be measured sequentially, the data acquisition time per resonator is short, making the technique an ideal wafer level characterization tool for high volume device testing. The devices used in our TCf experiments are comb-actuated clamped-clamped beam resonators fabricated using the SOIMUMPs process from MEMSCAP. The clamped-clamped architecture of these devices makes them especially prone to thermal-induced strain. A theoretical framework for analyzing the TCf of these resonators was also derived. Experiments on 16 sample devices show that altering the length L and width w of the clamped-clamped beam improves the TCf of the devices by up to 22%. From our TCf measurements, it was also deduced that a mismatch in the thermal expansion coefficients of the SOI structural and substrate layers caused the thermal-induced strain on our samples. The mismatch was determined to be 3.8 10-8 C-1 for one particular sample die.

Wong, C.-L.; Palaniapan, M.

2009-06-01

80

Design and development of a novel nuclear magnetic resonance detection for the gas phase ions by magnetic resonance acceleration technique  

NASA Astrophysics Data System (ADS)

Nuclear magnetic resonance (NMR) technique is a well-established powerful tool to study the physical and chemical properties of a wide range of materials. However, presently, NMR applications are essentially limited to materials in the condensed phase. Although magnetic resonance was originally demonstrated in gas phase molecular beam experiments, no application to gas phase molecular ions has yet been demonstrated. Here, we present a novel principle of NMR detection for gas phase ions based on a ``magnetic resonance acceleration'' technique and describe the design and construction of an apparatus which we are developing. We also present an experimental technique and some results on the formation and manipulation of cold ion packets in a strong magnetic field, which are the key innovations to detect NMR signal using the present method. We expect this novel method to lead new realm for the study of mass-selected gas-phase ions with interesting applications in both fundamental and applied sciences.

Fuke, K.; Tona, M.; Fujihara, A.; Sakurai, M.; Ishikawa, H.

2012-08-01

81

Antiferromagnetic properties of a water-vapor-inserted YBa2 Cu3 O6.5 compound studied byNMR, NQR, and ?SR  

NASA Astrophysics Data System (ADS)

We present a detailed NQR, nuclear magnetic resonance (NMR), and ?SR study of the magnetic phase obtained during a topotactic chemical reaction of YBa2Cu3O6.5 high-temperature superconductor with low-pressure water vapor. Cu65 -enriched samples have been used for NQR/NMR studies which allows to get a good resolution in the Cu(1) NQR and Cu(2) zero field NMR (ZFNMR) spectra. It is shown that the NQR spectrum of the starting material transforms progressively under insertion of water, and almost completely disappears when about one H2O molecule is inserted per unit cell. Similarly, a Cu65 ZFNMR signal characteristic of this water inserted material appears and grows with increasing water content, which indicates that the products of the reaction are nonsuperconducting antiferromagnetic phases in which the copper electronic magnetic moments in the CuO2 bilayers are ordered. The use of Cu65 -enriched samples allowed us to reliably resolve three different copper resonances which correspond to different internal magnetic fields. The antiferromagnetic phases are also felt by proton NMR which reveals two sites with static internal fields of 150 and about 15 Gauss, respectively. ?SR studies performed on a series of samples prepared in the same way as the C65u -enriched ones reveal two muon sites with the same local fields as the proton sites, which vanish at T?400K . This indicates that muons preferentially occupy proton vacancy sites, and that the magnetic phases have similar Nel temperatures as the other bilayer undoped cuprate compounds. An analysis of the internal fields on the different spin probes suggests that they can be all assigned to a single magnetic phase at large water content in which the Cu(1) electron spins order with those of the Cu(2) . The detailed evolution of the spectra with the progressive increase of water content is shown to be compatible with a coexistence of phases during the early stages ot the reaction. It appears that even samples packed in paraffin underwent a transformation of a substantial part of the sample after 6 years storage in atmosphere. Samples packed in Stycast epoxy resin heated moderately to a temperature (200C) undergo a reaction with epoxy decomposition products which yield the formation of the same final compound. It is clear that such effects should be considered quite seriously and avoided in experiments attempting to resolve tiny effects in these materials, such as those performed in some recent neutron scattering experiments.

Dooglav, A. V.; Egorov, A. V.; Mukhamedshin, I. R.; Savinkov, A. V.; Alloul, H.; Bobroff, J.; Macfarlane, W. A.; Mendels, P.; Collin, G.; Blanchard, N.; Picard, P. G.; King, P. J. C.; Lord, J.

2004-08-01

82

A Study of Transition-Metal Organometallic Complexes Combining (35) Cl Solid-State NMR Spectroscopy and (35) Cl?NQR Spectroscopy and First-Principles DFT Calculations.  

PubMed

A series of transition-metal organometallic complexes with commonly occurring metal?chlorine bonding motifs were characterized using (35) Cl solid-state NMR (SSNMR) spectroscopy, (35) Cl nuclear quadrupole resonance (NQR) spectroscopy, and first-principles density functional theory (DFT) calculations of NMR interaction tensors. Static (35) Cl ultra-wideline NMR spectra were acquired in a piecewise manner at standard (9.4?T) and high (21.1?T) magnetic field strengths using the WURST-QCPMG pulse sequence. The (35) Cl electric field gradient (EFG) and chemical shielding (CS) tensor parameters were readily extracted from analytical simulations of the spectra; in particular, the quadrupolar parameters are shown to be very sensitive to structural differences, and can easily differentiate between chlorine atoms in bridging and terminal bonding environments. (35) Cl?NQR spectra were acquired for many of the complexes, which aided in resolving structurally similar, yet crystallographically distinct and magnetically inequivalent chlorine sites, and with the interpretation and assignment of (35) Cl?SSNMR spectra. (35) Cl?EFG tensors obtained from first-principles DFT calculations are consistently in good agreement with experiment, highlighting the importance of using a combined approach of theoretical and experimental methods for structural characterization. Finally, a preliminary example of a (35) Cl?SSNMR spectrum of a transition-metal species (TiCl4 ) diluted and supported on non-porous silica is presented. The combination of (35) Cl?SSNMR and (35) Cl?NQR spectroscopy and DFT calculations is shown to be a promising and simple methodology for the characterization of all manner of chlorine-containing transition-metal complexes, in pure, impure bulk and supported forms. PMID:23907813

Johnston, Karen E; O'Keefe, Christopher A; Gauvin, Rgis M; Trbosc, Julien; Delevoye, Laurent; Amoureux, Jean-Paul; Popoff, Nicolas; Taoufik, Mostafa; Oudatchin, Konstantin; Schurko, Robert W

2013-08-01

83

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

Tang, Yijun; Zeng, Xiangqun; Liang, Jennifer

2010-01-01

84

A magnetic resonance device designed via global optimization techniques  

Microsoft Academic Search

In this paper we are concerned with the design of a small low-cost, low-field multipolar magnet for Magnetic Resonance Imaging with a high field uniformity. By introducing appropriate variables, the considered design problem is converted into a global optimization one. This latter problem is solved by means of a new derivative free global optimization method which is a distributed multi-start

Giampaolo Liuzzi; Stefano Lucidi; Veronica Piccialli; Antonello Sotgiu

2004-01-01

85

Oxidant-induced formation of a neutral flavosemiquinone in the Na+-translocating NADH:Quinone oxidoreductase (Na+-NQR) from Vibrio cholerae.  

PubMed

The Na(+)-translocating NADH:quinone oxidoreductase (Na(+)-NQR) from the human pathogen Vibrio cholerae is a respiratory flavo-FeS complex composed of the six subunits NqrA-F. The Na(+)-NQR was produced as His(6)-tagged protein by homologous expression in V. cholerae. The isolated complex contained near-stoichiometric amounts of non-covalently bound FAD (0.78 mol/mol Na(+)-NQR) and riboflavin (0.70 mol/mol Na(+)-NQR), catalyzed NADH-driven Na(+) transport (40 nmol Na(+)min(-1) mg(-1)), and was inhibited by 2-n-heptyl-4-hydroxyquinoline-N-oxide. EPR spectroscopy showed that Na(+)-NQR as isolated contained very low amounts of a neutral flavosemiquinone (10(-3) mol/mol Na(+)-NQR). Reduction with NADH resulted in the formation of an anionic flavosemiquinone (0.10 mol/mol Na(+)-NQR). Subsequent oxidation of the Na(+)-NQR with ubiquinone-1 or O(2) led to the formation of a neutral flavosemiquinone (0.24 mol/mol Na(+)-NQR). We propose that the Na(+)-NQR is fully oxidized in its resting state, and discuss putative schemes of NADH-triggered redox transitions. PMID:18454933

Tao, Minli; Casutt, Marco S; Fritz, Gnter; Steuber, Julia

2008-04-11

86

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

87

Surface Preparation and Characterization Techniques for Quartz Resonators.  

National Technical Information Service (NTIS)

An investigation was made of various polishing and cleaning techniques for quartz crystals. The surface topographies of polished crystals were investigated by transmission electron microscopy, with resolutions down to 15A. Large differences in surface qua...

C. Cook E. Hafner H. Wasshausen J. Vig M. Katz

1973-01-01

88

NMR and NQR study of the tetrahedral frustrated quantum spin system Cu2Te2O5Br2 in its paramagnetic phase  

NASA Astrophysics Data System (ADS)

The quantum antiferromagnet Cu2Te2O5Br2 was investigated by NMR and nuclear quadrupole resonance (NQR). The T125e NMR investigation showed that there is a magnetic transition around 10.5 K at 9 T, in agreement with previous studies. From the divergence of the spin-lattice relaxation rate, we ruled out the possibility that the transition could be governed by a one-dimensional divergence of the spin-spin correlation function. The observed anisotropy of the T125e shift was shown to be due to a spin polarization of the 5s2 E doublet of the [TeO3E] tetrahedra, highlighting the importance of tellurium in the exchange paths. In the paramagnetic state, Br NQR and NMR measurements led to the determination of the Br hyperfine coupling and the electric field gradient tensor, and to the spin polarization of Brp orbitals. The results demonstrate the crucial role of bromine in the interaction paths between Cu spins.

Comment, Arnaud; Mayaffre, Hadrien; Mitrovi?, Vesna; Horvati?, Mladen; Berthier, Claude; Grenier, Batrice; Millet, Patrice

2010-12-01

89

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

90

Methods for magnetic resonance analysis using magic angle technique  

SciTech Connect

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

91

Recent Developments of the Resonance Light Scattering Technique: Technical Evolution, New Probes and Applications  

Microsoft Academic Search

The resonance light scattering (RLS) technique, scanning simultaneously the excitation and emission monochromators of a common spectrofluorometer to detect enhanced RLS signals, has been used for designating bio?assemblies, aggregation species, and analytical purposes. Herein, we review the reports since our last mini?review in 2003 concerning the new derived RLS techniques, RLS probes, and their applications.

Jian Ling; Cheng Zhi Huang; Yuan Fang Li; Yun Fei Long; Qie Gen Liao

2007-01-01

92

Improvements in Techniques of Ultra-Fast Nuclear Magnetic Resonance Imaging  

Microsoft Academic Search

Techniques for the improvement of nuclear magnetic resonance (NMR) imaging are described. Topics covered are technique for the design of actively shielded NMR gradient coils based on algorithms combining linear and nonlinear optimizations, a method of mapping the radio frequency (rf) magnetic field generated by NMR rf coils with passive shielding structures, a highly efficient system for the exact simulation

Leping Zha

1995-01-01

93

Nondestructive characterization of prepreg ageing using nuclear magnetic resonance techniques  

Microsoft Academic Search

Initial results are presented on the application of NMR techniques to prepregs in order to characterize the crosslink state under exposure to room and elevated (50 C) temperature. The experiments were conducted with a MSL-400 Bruker NMR spectrometer and microimaging system which works at 400 MHz. Aside from the sensitive measurement of the cross-link density there is also the potential

E. Koeller; G. Dobmann; W. Kuhn

1990-01-01

94

Surface Plasmon Resonance: An Introduction to a Surface Spectroscopy Technique  

PubMed Central

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 an affordable homemade SPR device with all of its components accessible to visualization. This design allows ease of integration with electrochemistry and makes the device suitable for education. We describe a laboratory experiment in which students examine the relationship between the SPR angle and the solution refractive index at the interface and perform a coupled SPRelectrochemistry experiment. Students also study the antibodyantigen binding activity. Most of the experimental work was done as a project by a grade 12 high-school student under proper supervision. We believe that the SPR device and the SPR laboratory will enhance undergraduate chemical education by introducing students to this important modern instrumentation and will help students to learn and understand the molecular interactions occurring at interfaces.

Tang, Yijun; Zeng, Xiangqun; Liang, Jennifer

2010-01-01

95

Magnetic resonance elastography of liver: technique, analysis, and clinical applications.  

PubMed

Many pathological processes cause marked changes in the mechanical properties of tissue. MR elastography (MRE) is a noninvasive MRI based technique for quantitatively assessing the mechanical properties of tissues in vivo. MRE is performed by using a vibration source to generate low frequency mechanical waves in tissue, imaging the propagating waves using a phase contrast MRI technique, and then processing the wave information to generate quantitative images showing mechanical properties such as tissue stiffness. Since its first description in 1995, published studies have explored many potential clinical applications including brain, thyroid, lung, heart, breast, and skeletal muscle imaging. However, the best-documented application to emerge has been the use of MRE to assess liver disease. Multiple studies have demonstrated that there is a strong correlation between MRE-measured hepatic stiffness and the stage of fibrosis at histology. The emerging literature indicates that MRE can serve as a safer, less expensive, and potentially more accurate alternative to invasive liver biopsy which is currently the gold standard for diagnosis and staging of liver fibrosis. This review describes the basic principles, technique of performing a liver MRE, analysis and calculation of stiffness, clinical applications, limitations, and potential future applications. PMID:23423795

Venkatesh, Sudhakar K; Yin, Meng; Ehman, Richard L

2013-03-01

96

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

Microsoft Academic Search

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 solidsolid or solidliquid interfaces. In this study,

Delphine Le Guillou-Buffello; Grard Hlary; Marcel Gindre; Graciela Pavon-Djavid; Pascal Laugier; Vronique Migonney

2005-01-01

97

Analysis of Fano-line shapes from agile resonant waveguide grating sensors using correlation techniques  

NASA Astrophysics Data System (ADS)

The asymmetric Fano resonance lineshape, resulting from interference between background and a resonant scattering, is archetypal in resonant waveguide grating (RWG) reflectivity. Resonant profile shift resulting from a change of refractive index (from fluid medium or biomolecules at the chip surface) is classically used to perform label-free sensing. Lineshapes are sometimes sampled at discretized "detuning" values to relax instrumental demands, the highest reflectivity element giving a coarse resonance estimate. A finer extraction, needed to increase sensor sensitivity, can be obtained using a correlation approach, correlating the sensed signal to a zero-shifted reference signal. Correlation approach is robust to asymmetry of Fano lineshapes and allows more accurate determination than usual fitting options such as Gaussian or Lorentz shape fitting. Our findings are illustrated with resonance profiles from silicon nitride "chirped" RWGs operated at visible wavelengths. The scheme circumvents the classical but demanding spectral or angular scans: instead of varying angle or wavelength through fragile moving parts or special optics, a RWG structure parameter is varied. Then, the spatial reflectivity profiles of tracks composed of RWGs units with slowly varying filling factor (thus slowly varying resonance condition) are measured under monochromatic conditions. Extracting the resonance location using plain images of these "pixelated" Fano profiles allows multiplex refractive index based sensing with a sensitivity down to 210-5 RIU as demonstrated experimentally. This scheme based on a "Peak-tracking chip" demonstrates a new technique for bioarray imaging using a simpler set-up that maintains high performance with cheap lenses.

Bougot-Robin, K.; Wen, W. J.; Benisty, H.

2013-05-01

98

Surface defect inspection of spherical objects by the resonant sphere technique  

SciTech Connect

Ceramic materials, such as silicon nitride and silicon carbide, are important because of their high mechanical strength at high temperature and in nonlubricative environments. The weakness of these materials lies in their brittleness. Stress concentration caused by the existence of surface or subsurface cracks can lead to the total mechanical failure of parts. In this letter, we describe the application of the resonant-sphere technique to perform nondestructive evaluation of ceramic bearing balls. The technique had been shown to be capable of measuring various material properties, such as {ital V}{sub {ital s}} (shear wave velocity) and {nu} (Poisson's ratio). We use phase and amplitude measurements to simplify the evaluation of various resonance quality factors ({ital Q}), and we present, for the first time, the use of a resonance technique to propagate and detect surface waves on a sphere. We also show a decrease in {ital Q} for surface-wave modes due to the existence of surface cracks.

Hsieh, C.P.; Khuri-Yakub, B.T. (Edward L. Ginzton Laboratory, Stanford University, Stanford, California 94305-4085 (United States))

1992-04-13

99

Advances in magnetic resonance neuroimaging techniques in the evaluation of neonatal encephalopathy.  

PubMed

Magnetic resonance (MR) imaging has become an essential tool in the evaluation of neonatal encephalopathy. Magnetic resonance-compatible neonatal incubators allow sick neonates to be transported to the MR scanner, and neonatal head coils can improve signal-to-noise ratio, critical for advanced MR imaging techniques. Refinement of conventional imaging techniques include the use of PROPELLER techniques for motion correction. Magnetic resonance spectroscopic imaging and diffusion tensor imaging provide quantitative assessment of both brain development and brain injury in the newborn with respect to metabolite abnormalities and hypoxic-ischemic injury. Knowledge of normal developmental changes in MR spectroscopy metabolite concentration and diffusion tensor metrics is essential to interpret pathological cases. Perfusion MR and functional MR can provide additional physiological information. Both MR spectroscopy and diffusion tensor imaging can provide additional information in the differential of neonatal encephalopathy, including perinatal white matter injury, hypoxic-ischemic brain injury, metabolic disease, infection, and birth injury. PMID:17607141

Panigrahy, Ashok; Blml, Stefan

2007-02-01

100

Nondestructive characterization of prepreg ageing using nuclear magnetic resonance techniques  

SciTech Connect

Initial results are presented on the application of NMR techniques to prepregs in order to characterize the crosslink state under exposure to room and elevated (50 C) temperature. The experiments were conducted with a MSL-400 Bruker NMR spectrometer and microimaging system which works at 400 MHz. Aside from the sensitive measurement of the cross-link density there is also the potential to separate the influence of moisture content as a further parameter contributing to the aging process. It is shown that these experimental results correlate with results of destructive tests and document the potential of NMR as a NDT tool. An NMR-image of the moisture distribution in a glassfiber reinforced expoxy resin sample is shown. 17 refs.

Koeller, E.; Dobmann, G.; Kuhn, W. (Fraunhofer Institute for Nondestructive Testing, Saarbruecken (Germany, F.R.))

1990-01-01

101

Resonantly enhanced strip-line technique to measure microwave permeability of thin films  

NASA Astrophysics Data System (ADS)

The sensitivity of a reflective single-port strip-line technique is increased by 10-20 times by amplification of a measured reflectivity response at a set of resonance frequencies. The resonant behavior is organized by connecting the strip cell to a network analyzer through a capacitor with a long coaxial cable. The capacitance defines the amplification; the cable length defines the resonance frequencies. S-parameters of the coaxial-to-strip junction and the field inhomogeneity inside the cell are accounted for by a reference measurement of sample with known constitutive parameters. Two methods for permeability calculation are suggested. The fist method is based on the comparison of Lorentzian parameters of resonance reflectivity curves. The second method is based on numerical solution of Fresnel's equation. The enhancement is essential at low-frequency part of the band, where the cell reflectivity is close to unity and the sensitivity of non-resonant technique is poor. The technique sensitivity is estimated by permeability measurements of Al stripes with different cross-section.

Starostenko, S. N.; Rozanov, K. N.

2009-10-01

102

Left ventricular segmentation of cardiac magnetic resonance images using a novel edge following technique  

Microsoft Academic Search

This paper presents a novel edge following technique for image segmentation designed to segment the left ventricle in cardiac magnetic resonance (MR) images. This is a required step to determine the volume of left ventricle in a cardiac MR image, which is an essential tool for cardiac diagnosis. The traditional method for extracting them from cardiac MR images is by

Krit Somkantha; Nipon Theera-Umpon; Sansanee Auephanwiriyakul

2008-01-01

103

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

NASA Astrophysics Data System (ADS)

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

Eles, Philip Thomas

104

Polarization maintaining silica waveguide resonator optic gyro using double phase modulation technique.  

PubMed

Resonator micro optic gyro (RMOG) is a promising candidate for applications requiring small, light and robust gyros. In optical passive ring resonator gyros, clockwise and counter clockwise lightwaves are modulated at different frequencies to reduce the backscattering induced noise. The effectiveness of this technique, however, is determined by the carrier suppression level. Accurate modulation index and high environmental temperature stability is required for achieving high total carrier suppression for the traditional single phase modulation technique (SPMT). In this paper, we propose an RMOG based on the double phase modulation technique (DPMT). Compared with the traditional SPMT, two additional phase modulations are added to provide additional carrier suppression. It is found that the control accuracy of the modulation index and temperature stability is relaxed more than 30 times. It is easily performed for reducing the backscattering error below the shot noise limited sensitivity. The modulation parameters in the DPMT are analyzed and optimized. Based on the optimum parameters of the DPMT, a bias stability of 1.8510?? rad/s is successfully demonstrated in the polarization maintaining silica waveguide resonator with the length of 7.9 cm. This is the best result reported to date, to the best of our knowledge, for a waveguide type passive ring resonator gyro. PMID:21369295

Mao, Hui; Ma, Huilian; Jin, Zhonghe

2011-02-28

105

Determination of proteins with Fast Red VR by a corrected resonance light-scattering technique.  

PubMed

A simple corrected resonance light-scattering (CRLS) technique was established to correct for any distortion of the resonance light scattering (RLS) spectra resulting from molecular absorption. By using an absorption cell holder to change the propagation direction of the incident light beam of a common spectrofluorometer, the molecular absorption was directly measured through a spectrofluorometer. With measurements of the CRLS signals of the interaction of Fast Red VR (FRV) and proteins, we proved that the present correction for the RLS spectra in terms of the molecular absorption of excitation and scattering radiation can improve the detection sensitivity by about two fold. PMID:12608747

Yang, Chuan Xiao; Li, Yuan Fang; Huang, Cheng Zhi

2003-02-01

106

Inverse scattering technique for resonator alignment - Dependence of the accuracy on the finesse and mirror alignment  

NASA Astrophysics Data System (ADS)

The sensitivity of a GW interferometric antenna depends critically on the alignment of the Fabry-Perot (F-P) resonators placed in the two atms of a Michelson interferometer. To this end a servo system can be used for controlling the position and the orientation of the end mirrors by using error signals obtained by analyzing the transverse distribution of the beams reflected by the interferometers. This is tantamount to using an inverse scattering technique for gaining informations about the F-P resonators geometry. In this communication, an analytic expression of the components of the scattering matrix of a misaligned resonator excited by a mismatched and misaligned laser beam in presence of mirror aberrations and for finite mirror sizes is derived by representing the beams as superpositions of Gauss-Laguerre modes.

Solimeno, S.; Barone, Fabrizio; di Fiore, Luciano; Milano, Leopoldo; Pinto, Innocenzo M.

107

Resonance  

NSDL National Science Digital Library

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

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

2011-07-20

108

Basic aspects and main results of NMR-NQR spectroscopies in high-temperature superconductors  

NASA Astrophysics Data System (ADS)

After a mention of the structural, magnetic and electronic properties of high-temperature superconductors (HTSC), the basic principles of NMR-NQR experiments in these compounds are presented, emphasizing the marked differences and the novel aspects of the latter systems in comparison with metals and conventional superconductors. It follows a review of NMR-NQR spectra and relaxation rates in two-dimensional quantum antiferromagnets (particularly 0034-4885/61/10/002/img1) driven towards the superconducting state by charge doping. The main results obtained in the normal state of HTSC are summarized, while the problems of the spin-gap and of the superconducting fluctuations are discussed to a certain extent, by including the most recent contributions. An overview is given on the main conclusions derived from NMR-NQR experiments in the superconducting state. A section is devoted to the insights into the vortex lattice and the flux lines motion that have been obtained from NMR line narrowing, 0034-4885/61/10/002/img2 and echo dephasing. This review deals mostly with three systems, 0034-4885/61/10/002/img3, 0034-4885/61/10/002/img4 and 0034-4885/61/10/002/img5.

Rigamonti, A.; Borsa, F.; Carretta, P.

1998-10-01

109

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

Microsoft Academic Search

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

Faa-Jeng Lin; Rong-Jong Wai; Hsin-Hai Lin

1999-01-01

110

Fuzzy neural networks for identification and control of ultrasonic motor drive with LLCC resonant technique  

Microsoft Academic Search

This paper demonstrates the applications of fuzzy neural networks (FNNs) in the identification and control of the ultrasonic motor (USM). First, the USM is derived by a newly designed high-frequency two-phase voltage-source inverter using LLCC resonant technique. Then, two FNNs with varied learning rates are proposed to control the rotor position of the USM. The USM drive system is identified

Faa-Jeng Lin; Rong-Jong Wai; Rou-Yong Duan

1999-01-01

111

Anatomic and magnetic resonance imaging bases for the naso-maxillo-cheek flap technique  

Microsoft Academic Search

Summary A transfacial approach to the deep cranio-maxillo-facial areas by the naso-maxillo-cheek flap technique (NMCF) is indicated for the treatment of some bulky tumors of the naso-pharynx. The procedure requires precise preoperative imaging. This study presents the morphologic bases of this surgical access and the reasonable limits of the excision preoperatively determined by magnetic resonance imaging (MRI). 18 facial and

M. Prudhomme; J. Landgrebe; M. Maubon; C. Curioni; L. Clauser; G. Godlewskil

1998-01-01

112

Anatomic and magnetic resonance imaging bases for the naso-maxillo-cheek flap technique  

Microsoft Academic Search

A transfacial approach to the deep cranio-maxillo-facial areas by the naso-maxillo-cheek flap technique (NMCF) is indicated for the treatment of some bulky tumors of the naso-pharynx. The procedure requires precise preoperative imaging. This study presents the morphologic bases of this surgical access and the reasonable limits of the excision preoperatively determined by magnetic resonance imaging (MRI). 18 facial and skull

M. Prudhomme; J. Landgrebe; M. Maubon; C. Curioni; L. Clauser; G. Godlewski

1999-01-01

113

Detection of ammonium nitrate inside vehicles by nuclear quadrupole resonance  

Microsoft Academic Search

The development of a system for the detection of ammonium nitrate (AN) in vehicles by nuclear quadrupole resonance (NQR) is\\u000a described. The results from studies of the penetration of radiofrequency (RF) magnetic fields inside certain metal enclosures,\\u000a including full-scale vehicles, were critical in the design of a novel high-Q resonant probe. The probe was shaped not only for optimal penetration

J. Barras; M. J. Gaskell; N. Hunt; R. I. Jenkinson; K. R. Mann; D. A. G. Pedder; G. N. Shilstone; J. A. S. Smith

2004-01-01

114

Investigation of magnetic anisotropy in Co nanoparticles using ferromagnetic resonance technique  

NASA Astrophysics Data System (ADS)

Using ferromagnetic resonance (FMR) technique, we have investigated the temperature dependence and angular dependence of line width and resonance magnetic field of Co nanoparticles capped with novel alkane carboxylic acids of varying chain lengths. The magnetic properties such as blocking temperature and anisotropy sensitively depend on the chain length as evidenced by the temperature dependence of line width. These results indicate that the magnetic properties of these samples are critically governed by the interparticle interactions which are decided by the chain length. The presence of anisotropy even up to very high temperature above the blocking temperature observed in these studies confirms the presence of inter-particle magnetic interactions as well as intra-particle exchange interaction between the core and shell regions as evidenced by our earlier ac susceptibility and transverse susceptibility measurements on similar system.

Sendilkumar, A.; Kasture, Manasi; Patel, Pitamber; Ramana, C. V.; Prasad, B. L. V.; Srinath, S.

2010-01-01

115

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

116

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

117

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

118

Study on the Crystallization of the Metal Glass with the Ferromagnetic Resonance and Transmission Electron Microscopy Techniques.  

National Technical Information Service (NTIS)

The crystallization of the metal glass METGLAS 2826A has been studied with the ferromagnetic resonance and electron transmission microscopy techniques. The first-derivative linewidth of the absorption curve was measured for several times of isothermal tre...

R. S. Biasi R. W. D. Rodrigues R. Pascual C. S. Pessoa

1983-01-01

119

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

120

Magnetic resonance arthrography of the hip: technique and spectrum of findings in younger patients  

Microsoft Academic Search

Magnetic resonance(MR) imaging is the reference imaging technique in the evaluation of hip abnormalities. However, in some\\u000a pathological conditionssuch as lesions of the labrum, cartilaginous lesions, femoroacetabular impingement, intra-articular\\u000a foreign bodies, or in the pre-operative work-up of developmental dysplasia of the hipintra-articular injection of a contrast\\u000a medium is required to obtain a precise diagnosis. This article reviews the technical aspects,

Sbastien Aubry; Danny Blanger; Caroline Gigure; Martin Lavigne

2010-01-01

121

Diffusion of Al implanted into ?-Hf studied by means of the nuclear resonance technique  

NASA Astrophysics Data System (ADS)

The diffusion of Al in ?-Hf was studied in the 973 1298 K temperature range by using the nuclear resonance technique. The measurements show that the diffusion coefficient follows an Arrhenius behavior D(T)=D0exp(-Q/RT), where D0=(32)10-4 m2 s-l and Q=33710 kJ/mol. The activation energy is typical of a substitutional mechanism of diffusion, as can be deduced from self-diffusion measurements. On the other hand, differences between the present and previous published results can be attributed to the different purity of the samples used in each experiment.

Bernardi, F.; Behar, M.; Dos Santos, J. H. R.; Dyment, F.

2005-01-01

122

63,65Cu NQR study of Zn and Ni doped YBa 2Cu 3O 7  

Microsoft Academic Search

63,65Cu NQR measurements have been performed on Zn and Ni doped YBCO (YBa2Cu3?xMxO7, M?Zn or Ni, x=0.0 ? 0.09). Distinctive differences due to the nonmagnetic Zn and the magnetic Ni dopants substituted for copper are compared microscopically based on the plane and the chain 63,65Cu NQR data. Both spin-lattice and spin-spin relaxation rates decrease for Zn doped YBCO whereas they

K. S. Han; B. J. Mean; K. H. Lee; D. H. Kim; S. W. Seo; Moohee Lee; W. C. Lee; J. S. Cho

2000-01-01

123

Charge-inhomogeneity doping relations in Y Ba2 Cu3 Oy detected by angle-dependent nuclear quadrupole resonance  

NASA Astrophysics Data System (ADS)

The origin of charge inhomogeneity in YBa2Cu3Oy is investigated using an experimental method designed to determine the nuclear quadrupole resonance (NQR) asymmetry parameter ? for very wide NQR lines at different positions on the line. The method is based on the measurement of the echo intensity as a function of the angle between the radio frequency field H1 and the principal axis of the electric field gradient. Static charge inhomogeneity deduced from ?>0 is found in this compound, but only in conjunction with oxygen deficiency. This limits considerably the possible forms of charge inhomogeneity in bulk YBa2Cu3Oy .

Ofer, Rinat; Levy, Shahar; Kanigel, Amit; Keren, Amit

2006-01-01

124

Dynamics of paramagnetic agents by off-resonance rotating frame technique  

NASA Astrophysics Data System (ADS)

Off-resonance rotating frame technique offers a novel tool to explore the dynamics of paramagnetic agents at high magnetic fields (B0 > 3 T). Based on the effect of paramagnetic relaxation enhancement in the off-resonance rotating frame, a new method is described here for determining the dynamics of paramagnetic ion chelates from the residual z-magnetizations of water protons. In this method, the dynamics of the chelates are identified by the difference magnetization profiles, which are the subtraction of the residual z-magnetization as a function of frequency offset obtained at two sets of RF amplitude ?1 and pulse duration ?. The choices of ?1 and ? are guided by a 2-D magnetization map that is created numerically by plotting the residual z-magnetization as a function of effective field angle ? and off-resonance pulse duration ?. From the region of magnetization map that is the most sensitive to the alteration of the paramagnetic relaxation enhancement efficiency R1?/R1, the ratio of the off-resonance rotating frame relaxation rate constant R1? verse the laboratory frame relaxation rate constant R1, three types of difference magnetization profiles can be generated. The magnetization map and the difference magnetization profiles are correlated with the rotational correlation time ?R of Gd-DTPA through numerical simulations, and further validated by the experimental data for a series of macromolecule conjugated Gd-DTPA in aqueous solutions. Effects of hydration water number q, diffusion coefficient D, magnetic field strength B0 and multiple rotational correlation times are explored with the simulations of the magnetization map. This method not only provides a simple and reliable approach to determine the dynamics of paramagnetic labeling of molecular/cellular events at high magnetic fields, but also a new strategy for spectral editing in NMR/MRI based on the dynamics of paramagnetic labeling in vivo.

Zhang, Huiming; Xie, Yang

2006-12-01

125

A new pulse width reduction technique for pulsed electron paramagnetic resonance spectroscopy.  

PubMed

We present a new technique for a microwave pulse modulator that generates a short microwave pulse of approximately 1ns for use in an electron paramagnetic resonance (EPR) spectrometer. A quadruple-frequency multiplier that generates a signal of 16-20GHz from an input of 4-5GHz was employed to reduce the rise and fall times of the pulse prepared by a PIN diode switch. We examined the transient response characteristics of a commercial frequency multiplier and found that the device can function as a multiplier for pulsed signal even though it was designed for continuous wave operation. We applied the technique to a Ku band pulsed EPR spectrometer and successfully observed a spin echo signal with a broad excitation bandwidth of approximately 1.6mT using 80 degrees pulses of 1.5ns. PMID:18248828

Ohba, Yasunori; Nakazawa, Shigeaki; Kazama, Shunji; Mizuta, Yukio

2007-12-15

126

14N pulsed nuclear quadrupole resonance. 1. Nutation experiments in the case of an axially symmetric electric field gradient tensor  

Microsoft Academic Search

An exact theory based on density matrix calculations is provided for assessing the nuclear quadrupole resonance (NQR) behaviour of a spin 1 (14N) subjected to a single radio-frequency pulse. It concerns a powder sample in zero magnetic field with the assumption of an axially symmetric electric field gradient tensor. Theoretical results, in terms of signal evolution as a function of

B. Cordier; D. Grandclaude; A. Retournard; L. Merlat; D. Canet

2005-01-01

127

Resonance  

NSDL National Science Digital Library

All About Circuits is a website that âprovides 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.

2008-07-07

128

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.

Maniam, Santhi; Szklaruk, Janio

2010-01-01

129

ABO blood-typing using an antibody array technique based on surface plasmon resonance imaging.  

PubMed

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

2013-09-09

130

Nuclear Quadrupole Resonance Studies of Charge Distributions in Molecular Solids.  

NASA Astrophysics Data System (ADS)

A detailed description of an NMR-NQR double resonance spectrometer designed and constructed in this laboratory is given, including some instruction on its use. ('14)N NQR data obtained by pulse methods for six classes of nitrogen-containing compounds are presented and analyzed in the framework of the Townes and Dailey theory. A study of the anti-cancer drugs cyclophosphamide, isophosphamide and triphosphamide suggests the existence of a correlation between the substance's chemotherapeutic efficacy and the (pi) - (sigma)(,NP) charge density at the trigonal nitrogen. Satisfactory correlations of the NQR spectra of 22 monosubstituted anilines with both the Hammett (sigma) parameters and the in vitro biological activities of the corresponding sulfanilamides have been found, indicating that the nitrogen lone-pair orbital is more sensitive than the nitrogen-carbon sigma orbital is to substituent effects. NQR spectra of several N-acetyl amino acids and related compounds are reported. The inductive effect of the chloroacetyl group on the nitrogen is discussed. A positive correlation between the (pi) - (sigma)(,NC) electron density at the nitrogen and the Taft inductive parameter (sigma)* is observed, suggesting that the nitrogen (pi) -charge density in the N-acetyl amino acids does not vary appreciably. Both ('14)N and ('35)Cl NQR data have been obtained for a series of compounds containing nitrogen directly bonded to chlorine. The existence of a linear correlation between the ('14)N and ('35)Cl quadrupole coupling constants is interpreted in terms of a simple model dealing with charge excesses and deficiencies at the respective nuclei. A study of two complexes of 4-aminopyridine (4AP) addresses the loss of pyridine nitrogen lone-pair charge upon formation of the strong and asymmetric N-H-N bond characteristic of these complexes. Evidence of hydrogen bonding interactions involving the amino nitrogens is found to be in agreement with a published neutron diffraction study. ('14)N NQR data for seven organic dye cations and one free base are presented. The cations are weakly paramagnetic at 77 K, exhibiting broad and featureless EPR spectra characteristic of weak charge-transfer complexes. The positive charge in the cations is largely delocalized. The existence of a simple relationship between the ('14)N NQR data and optical properties for three cyanine laser dyes is discussed.

Greenbaum, Steven Garry

131

Detection of Bacterial Magnetofossils with Ferromagnetic Resonance and Rock Magnetic Techniques  

NASA Astrophysics Data System (ADS)

Intracellular biomineralization of magnetite is a biochemical process used by members of the Bacteria, Protist, and Animal kingdoms, and the fossil remains of this process on Earth (termed magnetofossils) have been documented in sediments as old as the ~2 Byr Gunflint Chert. Magnetofossils 4 Byr old have also been reported from carbonates in the Martian meteorite ALH84001; if this interpretation is correct, they represent the oldest evidence for life yet found. Past techniques for identification of bacterial magnetofossils have relied on the use of particle extraction and high-resolution electron microscopy (HRTEM). Because these techniques are time-consuming and fairly complex, they are not appropriate for screening large volumes of sediments on Earth and could not be used remotely on a Martian lander. For this reason, we have been testing a variety of ferromagnetic resonance and low-temperature rock magnetic techniques to determine if they are capable of identifying correctly rock samples known to contain abundant magnetofossils. An instrument capable of making such a determination, if deployed on the Martian surface, could be extraordinarily valuable for selecting samples for return to Earth. Several features of the ferromagnetic resonance (FMR) spectra have signatures only displayed by pure samples of magnetite from the magnetotactic bacteria, and from samples known to contain abundant magnetofossils. These unique features apparently arise from the elongated shape and narrow size distribution of the single-domain magnetite produced by these bacteria. Preliminary results from ALH84001 carbonates also have these features. We are also currently obtaining FMR spectra and low-temperature rock magnetic data on samples of Archean and Early Proterozoic sediments from Australia to search for older evidence of intracellular magnetite biomineralization on Earth.

Kirschvink, J. L.; Kim, S.; Weiss, B.

2001-12-01

132

Magnetic resonance spectroscopy editing techniques of coupled spin systems at high field  

NASA Astrophysics Data System (ADS)

Magnetic resonance spectroscopy (MRS) provides a non-invasive tool for investigating chemical concentrations in the human brain. The detection of metabolites is useful in understanding functional pathways in healthy and diseased states. Many important metabolites are composed of multiple interacting spins coupled through chemical bonds in the molecule. Whereas the observation of strong uncoupled (singlet) resonances is straightforward, complex coupling patterns and signal overlap often hinder the detection of coupled spin systems, rendering quantification problematic. One of the primary goals of this project is to investigate spectral editing techniques to detect coupled spin systems and provide a means for increasing the accuracy of quantification. A new method of spectral editing based on subtraction spectroscopy is proposed, which relies on signal differences at constant echo time (TE) produced by varying the inter-pulse delays in an asymmetric PRESS sequence. The method requires no spectrally selective pulses or multiple quantum filters, and can be easily implemented with a standard PRESS sequence. All non-varying spectral information is maintained, in contrast to other popular editing techniques. In terms of strongly coupled spin systems, the procedure is demonstrated for glutamate and glutamine discrimination, as well as simulated optimization of field strength for detection of several strongly coupled metabolites. To produce the necessary TE space variations for weakly coupled systems, the flip angle of the second refocusing pulse was varied. This technique was applied for the detection of gamma-aminobutyric acid, which is completely obscured at standard clinical field strengths. A second editing method investigated the optimization of PRESS timing parameters at multiple field strengths for the simultaneous detection of glutamate and glutamine in vivo, by maximizing the signal yield and minimizing the significant overlap at lower field strengths. Finally, the effect of radiofrequency interference effects was studied at high field to investigate signal losses due to reduced excitation and refocusing in spectroscopic images. Possible differences between coupled and uncoupled spin systems were investigated in spectroscopic imaging at 4.7 T.

Snyder, Jeff

133

Spatial electron density distribution of the chlorine atoms in organic and complex compounds as studied by NQR and MNDO  

Microsoft Academic Search

Quantitative correlation of the NQR frequencies and asymmetry parameters of the EFG at nuclei having spin I = 32 with the population of the indicator atom (at Npx = 2) and nonaxiality of its electron distribution has been obtained. The Npy and Npz populations of the Cl atoms in some chloro-containing organic and coordination compounds have been calculated using the

V. P. Feshin; M. Yu. Konshin

1995-01-01

134

Dielectric characterization of printed wiring board materials using ring resonator techniques: a comparison of calculation models  

Microsoft Academic Search

Ring resonator structures are widely used to characterize the frequency and temperature dependence of the relative permittivity and loss tangent of printed wiring board materials. Several theoretical models for the ring resonator structures have been presented since the first ring resonator application. In this paper, the theoretical models of the ring resonator structure are adapted for calculating the relative permittivity

Janne-Matti Heinola; Kimmo Tolsa

2006-01-01

135

Detection of ammonium nitrate inside vehicles by Nuclear Quadrupole Resonance  

Microsoft Academic Search

\\u000a Nuclear quadrupole resonance (NQR) has been demonstrated for the detection of explosives in a number of potential applications,\\u000a including baggage screening, mail screening and landmine detection. A further highly desirable application concerns the detection\\u000a of explosives concealed within a vehicle, which from the point of view of RF penetration can be considered as a large metal\\u000a box with holes in

J. Barras; M. J. Gaskell; N. Hunt; R. I. Jenkinson; K. Mann; D. Peddar; G. N. Shilstone; J. A. S. Smith

136

Novel Technique for Cardiac Electromechanical Mapping with Magnetic Resonance Imaging Tagging and an Epicardial Electrode Sock  

PubMed Central

Near-simultaneous measurements of electrical and mechanical activation over the entire ventricular surface are now possible using magnetic resonance imaging tagging and a multielectrode epicardial sock. This new electromechanical mapping technique is demonstrated in the ventricularly paced canine heart. A 128-electrode epicardial sock and pacing electrodes were placed on the hearts of four anesthetized dogs. In the magnetic resonance scanner, tagged cine images (815 ms/frame) and sock electrode recordings (1000 Hz) were acquired under right-ventricular pacing and temporally referenced to the pacing stimulus. Electrical recordings were obtained during intermittent breaks in image acquisition, so that both data sets represented the same physiologic state. Since the electrodes were not visible in the images, electrode recordings and cine images were spatially registered with Gd-DTPA markers attached to the sock. Circumferential strain was calculated at locations corresponding to electrodes. For each electrode location, electrical and mechanical activation times were calculated and relationships between the two activation patterns were demonstrated. This method holds promise for improving understanding of the relationships between the patterns of electrical activation and contraction in the heart.

Faris, Owen P.; Evans, Frank J.; Ennis, Daniel B.; Helm, Patrick A.; Taylor, Joni L.; Chesnick, A. Scott; Guttman, Michael A.; Ozturk, Cengizhan; Mcveigh, Elliot R.

2005-01-01

137

Novel Design of Sagnac Interferometry Assisted with Surface Plasmon Resonance Based Sensor Technique  

NASA Astrophysics Data System (ADS)

In this work, we demonstrate a novel design to investigate interfacial reaction of optical activity materials, utilizing a Sagnac interferometer assisted with surface plasmon resonance based sensor technique. Upon application to interrogate optical activity, the type-2 optical configuration of close loop in this work can entirely encircle the interaction zone of surface plasmon resonance reacting with optical activity medium, while the type-1 optical configuration of close loop does partially. The greater the geometrical phase owing to the encircled interaction zone between optical activity medium and polarized light, the larger the phase shift of interference pattern modulated by the concentration of optical activity medium. The slope of phase shift in interference phase pattern of p-wave vs. concentration of dextrose solution determined with this method is greatly improved, 3000 times better than that with Lee's method, 18,600 times with Lin's method, and 222,000 times with Chou's method. Besides, the pinch point of phase shift vs. concentration indicates the ending of interference pattern phase shift as the concentration of each tested optical activity medium keeps climbing up, and can reflect the strong dependence of molecular shape during interfacial adsorption.

Li, Yu-Chu M.; Huang, Chao-Ming; Chang, Wei-Chin; Lin, Kai-Jan; Chang, Sheng-Chih; Yao, Sheng-Cheng

2011-06-01

138

Implant stability evaluation by resonance frequency analysis in the fit lock technique. A clinical study.  

PubMed

Surgical procedures for the application of implants in the lateral-superior sectors are affected by the availability of the residual bone. When this condition is lower than 5 mm it is recommended that techniques involving two therapeutic phases, a reconstructive and an applicative one, as reported in the international literature, are adopted. The authors propose here a new method with the potential to apply implants simultaneously with the reconstructive phase. The aim of this longitudinal retrospective study was to evaluate the stability of implants applied with the fit lock technique in the upper maxillarys in us with bone availability lower than 4 mm by measuring resonance frequency at different follow-up periods The seme as urements, carried out on 30 implants, were analysed with specific statistical procedures. The results indicate that the stability of the implants inserted with the fit lock method increases progressively over time in a statistically significant manner. The stability recorded after one year from the insertion (ISQ T2) is significantly higher than that recorded after six months (ISQ T1), and this is significantly higher than that recorded at the time of implant placement (ISQ T0). The implants inserted in the maxillary zones with scarce bone availability and applied with this technique showed a similar stability as reported with other techniques. In light of the results, the authors confirm that the primary stability represents the basic requirement to guarantee a correct healing of the implant and demonstrate that the fit lock technique also all ows reaching this condition when bone availability is minimal. PMID:23991271

Falisi, Giovanni; Galli, Massimo; Velasquez, Pedro Vittorini; Rivera, Juan Carlos Gallegos; Di Paolo, Carlo

2013-06-25

139

Implant stability evaluation by resonance frequency analysis in the fit lock technique. A clinical study  

PubMed Central

Summary Surgical procedures for the application of implants in the lateral-superior sectors are affected by the availability of the residual bone. When this condition is lower than 5 mm it is recommended that techniques involving two therapeutic phases, a reconstructive and an applicative one, as reported in the international literature, are adopted. The authors propose here a new method with the potential to apply implants simultaneously with the reconstructive phase. The aim of this longitudinal retrospective study was to evaluate the stability of implants applied with the fit lock technique in the upper maxillarys in us with bone availability lower than 4 mm by measuring resonance frequency at different follow-up periods The seme as urements, carried out on 30 implants, were analysed with specific statistical procedures. The results indicate that the stability of the implants inserted with the fit lock method increases progressively over time in a statistically significant manner. The stability recorded after one year from the insertion (ISQ T2) is significantly higher than that recorded after six months (ISQ T1), and this is significantly higher than that recorded at the time of implant placement (ISQ T0). The implants inserted in the maxillary zones with scarce bone availability and applied with this technique showed a similar stability as reported with other techniques. In light of the results, the authors confirm that the primary stability represents the basic requirement to guarantee a correct healing of the implant and demonstrate that the fit lock technique also all ows reaching this condition when bone availability is minimal.

Falisi, Giovanni; Galli, Massimo; Velasquez, Pedro Vittorini; Rivera, Juan Carlos Gallegos; Di Paolo, Carlo

2013-01-01

140

Synthesis and Characterization of Zinc Ferrite by XRD, Vsm and Electron Spin Resonance Techniques  

NASA Astrophysics Data System (ADS)

In this report, the synthesis of zinc ferrite (ZnFe2O4) by co-precipitation method has been presented along with its subsequent characterization by using X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and electron spin resonance (ESR) techniques. The obtained XRD results of as-synthesized sample indicates the cubic spinel phase formation, which was confirmed from the XRD data of the above calcined sample at 1000C. By using VSM, a complex magnetic structure was observed with substantial change on calcined sample. The ESR result of zinc ferrite sample studied at room temperature was found to be significantly different from that of the low temperature results, especially after heat-treatment.

Nayak, Pranaba K.; Jothiramalingam, R.

2013-02-01

141

Evaluation of Possible Nuclear Magnetic Resonance Diagnostic Techniques for Tokamak Experiments  

SciTech Connect

Potential applications of nuclear magnetic resonance (NMR) diagnostic techniques to tokamak experiments are evaluated. NMR frequencies for hydrogen isotopes and low-Z nuclei in such experiments are in the frequency range approximately equal to 20-200 MHz, so existing RF [radio-frequency] antennas could be used to rotate the spin polarization and to make the NMR measurements. Our tentative conclusion is that such measurements are possible if highly spin polarized H or (superscript)3He gas sources (which exist) are used to fuel these plasmas. In addition, NMR measurements of the surface layers of the first wall (without plasma) may also be possible, e.g., to evaluate the inventory of tritium inside the vessel.

S.J. Zweben; T.W. Kornack; D. Majeski; G. Schilling; C.H. Skinner; R. Wilson

2002-08-05

142

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

143

Development of exp 239 Pu Total Cross Section Multilevel Parameters Determination Technique by Analysing Experiments on Neutron Transmission in Resolved Resonance Region.  

National Technical Information Service (NTIS)

The aim of this work is development of S-matrix multilevel resonance parameters determination technique with neutron transmission data used in resolved resonance region. Experimental transmission data values were obtained for the Pu-239 thickness range 0....

T. Bakalov G. Il'chev S. Toshkov V. F. Ukraintsev Chan Khan Maj

1981-01-01

144

Complimentary effect of yogic sound resonance relaxation technique in patients with common neck pain  

PubMed Central

Background: Studies have shown that conventional treatment methods with drugs, physiotherapy and exercises for common neck pain (CNP) may be inadequate. Yoga techniques have been found to be effective complimentary therapies in chronic low back pain and also for stress reduction in other diseases. Objective: The aim of the study was to examine the complimentary role of a yogic relaxation called mind sound resonance technique (MSRT) in non-surgical management of CNP. Materials and Methods: In this randomized controlled study, 60 patients with CNP were assigned to two groups (yoga, n=30) and (control, n=30). The yoga group received yogic MSRT for 20 minutes in supine position after the conventional physiotherapy program for 30 minutes using pre-recorded audio CD and the control group had non-guided supine rest for 20 minutes (after physiotherapy), for 10 days. MSRT provides deep relaxation for both mind and body by introspective experience of the sound resonance in the whole body while repeating the syllables A, U, M and Om and a long chant (Mahamrityunjaya mantra) several times in a meaningful sequence. Both the groups had pre and post assessments using visual pain analog scale, tenderness scoring key, neck disability score (NDS) questionnaire, goniometric measurement of cervical spinal flexibility, and state and trait anxiety inventory-Y1 (STAI-Y1). Results: Mann-Whitney U test showed significant difference between groups in pain (P<0.01), tenderness (P<0.01), neck movements (P<0.01). NDS (P<0.01) and state anxiety (STAI-Y1) showed higher reduction in yoga (P<0.01) than that in the control group. Wilcoxons test showed a significant improvement in both groups on all variables (P<0.01). Conclusions: Yoga relaxation through MSRT adds significant complimentary benefits to conventional physiotherapy for CNP by reducing pain, tenderness, disability and state anxiety and providing improved flexibility.

Yogitha, Bali; Nagarathna, R; John, Ebnezar; Nagendra, HR

2010-01-01

145

Open-loop operation experiments in a resonator fiber-optic gyro using the phase modulation spectroscopy technique.  

PubMed

A detection system in the resonator fiber-optic gyro is set up by the phase modulation (PM) spectroscopy technique. The slope of the demodulated curve near the resonant point is found to affect the ultimate sensitivity of the gyro. To maximize the demodulated signal slope, the modulation frequency and index are optimized by the expansion of the Bessel function and optical field overlapping method. Using different PM frequencies for the light waves, the open-loop gyro output signal is observed. The modulation frequency in this PM technique is limited only by the cutoff frequency of the LiNbO3 phase modulators, which can reach several gigahertz. This detection technique and system can be applied to the resonator micro-optic gyro with a less than 10 cm long integrated optical ring. PMID:17068533

Zhang, Xu-lin; Ma, Hui-Iian; Jin, Zhong-he; Ding, Chun

2006-11-01

146

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

147

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

PubMed

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

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

2012-10-26

148

Electron Spin Resonance Experiments on Donors in Silicon. I. Electronic Structure of Donors by the Electron Nuclear Double Resonance Technique  

Microsoft Academic Search

The ground-state wave function of the antimony, phosphorus, and arsenic impurities in silicon has been investigated by means of the electron nuclear double resonance (ENDOR) method. By this method the hyperfine interactions of the donor electron with the Si29 nuclei situated at different lattice sites were obtained. The isotropic part of the hyperfine interaction agreed with the theory of Kohn

G. Feher

1959-01-01

149

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

2013-02-04

150

Interaction of daunomycin antibiotic with human serum albumin: Investigation by resonant mirror biosensor technique, fluorescence spectroscopy and molecular modeling methods  

Microsoft Academic Search

Daunomycin (DM) is a clinically used antitumor anthracycline antibiotic, which is transported primarily by human serum albumin (HSA) in the blood. Binding characteristics are therefore of interest for both the pharmacokinetics and pharmacodynamics of DM. A new optical biosensor technique based on the resonant mirror was used to characterize interaction of DM with HSA at different temperatures and the affinity

Kai Tang; Yi-Min Qin; Ai-Hua Lin; Xing Hu; Guo-Lin Zou

2005-01-01

151

Application of the electron spin resonance technique for quantitative evaluation of the resorption rate of irradiated bone grafts  

Microsoft Academic Search

The electron spin resonance (ESR) technique has been applied to the investigation of the resorption and creeping substitution of radiosterilized (3.3 Mrads dose) bone grafts in rabbits and dogs. The stable ESR signal arising from the radiation-induced structural defect in bone mineral was used as a biological label. the spin concentration and the total number of paramagnetic centres were measured

K. Ostrowski; A. Dziedzic-Goc?awska; W. Stachowicz; J. Michalik; E. Tarsoly; A. Komender

1971-01-01

152

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

153

First-principles study of (75)As NQR in arsenic-chalcogenide compounds.  

PubMed

We present a theoretical study of the nuclear quadrupole interaction, ?(Q), of (75)As in crystalline and amorphous materials containing sulfur and selenium, and compare them with experiment. We studied a combination of hydrogen-terminated molecular clusters and periodic cells at various levels of quantum chemical theory. The results show clearly that the standard density functional theory (DFT) approximations, LDA and GGA, underestimate the nuclear quadrupole (NQR) interaction systematically, while Hartree-Fock theory overestimates it to an even greater degree. However, various levels of configuration interaction and the B3LYP hybrid exchange-correlation functional, which includes some exact exchange, give very good quantitative agreement for As bonded only to the chalcogen species. As-As bonds require highly converged basis sets. We have performed a systematic study of the effect of local distortions around an arsenic atom on ?(Q) and ?. Using a simple, semiclassical model, we have combined our total energy results with our NQR calculations to predict ?(Q) lineshapes for bond angle and bond length distortions. Our predictions for lineshape, including first and second moments, are in excellent agreement with the results of Su et al for a-As(2)S(3), a-As(2)Se(3) and a-AsSe. We offer new insight into the distortions that led to this inhomogeneous broadening. Our results show clearly that, for trivalent arsenic atoms with zero or one arsenic nearest neighbor, symmetric bond stretching is the predominant contributor to the ?(Q) linewidth. However, in the presence of two arsenic nearest neighbors, distortions of the As-As-As apex angle dominates and, in fact, leads to a much larger second moment, in agreement with experiment. PMID:21406910

Edwards, Arthur H; Taylor, P C; Campbell, Kristy A; Pineda, Andrew C

2011-01-19

154

Magnetic resonance imaging and spectroscopic techniques in the study of tumor biology  

SciTech Connect

Non-invasive magnetic resonance imaging and spectroscopic techniques can be used to obtain information regarding key physiological parameters governing the malignant potential of tumors. Techniques to characterize the invasiveness, metabolism, oxygenation, and vascularization of tumors are developed and applied on sub-cutaneously implanted rat prostatic adenocarcinoma tumor models and on an in situ rat brain glioma model. Serial contrast enhanced imaging studies allow the size and extent (invasiveness) of tumors to be monitored. Histological sections and gadolinium enhancement patterns in the rat glioma model similar to those observed in spontaneously occurring human gliomas demonstrate the appropriateness of this animal model. Dynamic time course scans following administration of gadolinium demonstrate the existence of heterogeneous blood flow within these lesions. Localized proton and phosphorous NMR spectroscopy is used in measuring tumor metabolism and bioenergetic status. Proton spectral patterns in the rat prostate tumor have have been shown to be related to the physiological state of the tissue (active tumor versus necrosis). Changes in proton metabolite levels with brain tumor growth in the RT2 model are similar to those observed in human gliomas. Qualitative indications of tumor tissue hypoxia are obtained in vivo using a fluorine-19 labeled nitroimidazole. This compound binds to hypoxic cells via bioreductive reactions and is detected by fluorine-19 NMR up to 48 hours following administration to animals with prostate tumors greater than 3 cm in diameter and gliomas greater than 0.5 cm in diameter. Methods for measuring and visualizing heterogeneous distributions of tumor transverse and longitudinal water relaxation times in a localized fashion are also developed. Using these protocols, transverse relaxation times have been shown to increase with increasing size of the lesion and might also be useful in evaluating the malignant potential of other tumors.

Gill, M.

1993-01-01

155

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

156

In vivo biodistribution and biological impact of injected carbon nanotubes using magnetic resonance techniques  

PubMed Central

Background: Single-walled carbon nanotubes (SWCNT) hold promise for applications as contrast agents and target delivery carriers in the field of nanomedicine. When administered in vivo, their biodistribution and pharmacological profile needs to be fully characterized. The tissue distribution of carbon nanotubes and their potential impact on metabolism depend on their shape, coating, and metallic impurities. Because standard radiolabeled or fluorescently-labeled pharmaceuticals are not well suited for long-term in vivo follow-up of carbon nanotubes, alternative methods are required. Methods: In this study, noninvasive in vivo magnetic resonance imaging (MRI) investigations combined with high-resolution magic angle spinning (HR-MAS), Raman spectroscopy, iron assays, and histological analysis ex vivo were proposed and applied to assess the biodistribution and biological impact of intravenously injected pristine (raw and purified) and functionalized SWCNT in a 2-week longitudinal study. Iron impurities allowed raw detection of SWCNT in vivo by susceptibility-weighted MRI. Results: A transitional accumulation in the spleen and liver was observed by MRI. Raman spectroscopy, iron assays, and histological findings confirmed the MRI readouts. Moreover, no acute toxicological effect on the liver metabolic profile was observed using the HR-MAS technique, as confirmed by quantitative real-time polymerase chain reaction analysis. Conclusion: This study illustrates the potential of noninvasive MRI protocols for longitudinal assessment of the biodistribution of SWCNT with associated intrinsic metal impurities. The same approach can be used for any other magnetically-labeled nanoparticles.

Al Faraj, Achraf; Fauvelle, Florence; Luciani, Nathalie; Lacroix, Ghislaine; Levy, Michael; Cremillieux, Yannick; Canet-Soulas, Emmanuelle

2011-01-01

157

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

158

An efficient birdcage resonator at 2.5 MHz using a novel multilayer self-capacitance construction technique.  

PubMed

The birdcage resonator, well appreciated for its high signal-to-noise ratio and its magnetic field uniformity characteristics, operates efficiently in mid- to high-field MRI systems but, unfortunately not for low-field (< 0.4 T) applications. The inherently low inductance of the birdcage architecture is the main obstacle to achieving low-frequency resonance because of the need to use very high-value capacitors for the tuning. Small-case-size, high-value ceramic capacitors are known to have high dissipation factors which when used in the fabrication of RF coils could result in poor efficiency. To overcome this limitation, a novel technique known as multilayer self-capacitance (MLSC) construction has been developed and a prototype 2.5 MHz bird-cage resonator of length 25 cm and diameter 20 cm has been built. The technique involves the modification of the leg sections of the conductors constituting the bird cage into integrated capacitors using very low-loss materials as dielectrics. The observed unloaded Q-factor was 267 using the MLSC construction, and when loaded with a 16-cm-diameter bottle of 0.45% saline, its Q dropped to 246. The RF field uniformity plots have demonstrated that the MLSC technique has no adverse effects on the magnetic field homogeneity of the bird-cage resonator. PMID:8749735

Yeung, D; Hutchison, J M; Lurie, D J

159

Formation of Resonances with Final State Photons in Two Photon Interactions, and Development of Calorimetric Techniques.  

National Technical Information Service (NTIS)

In this thesis, resonances produced in two photon interactions were investigated with the TASSO detector at PETRA. The eta/sup '/ and A/sub 2/ resonances were studied in a final state of charged pions and low energy photons. The couplings of these resonan...

R. Mir

1986-01-01

160

NQR study of local structures and cooling rate dependent superconductivity in La sub 2 CuO sub 4+. delta  

SciTech Connect

Structural properties of oxygen-annealed polycrystals of La{sub 2}CuO{sub 4 + {delta}} ({delta}{approximately}0.03) have been studied using {sup 139}La NQR spectroscopy. Superconducting critical temperatures were found to depend on the rate of cooling through a narrow temperature range at about 195K. Preliminary analysis of the {sup 139}La NQR spectra suggest that the oxygen-rich phase-separated region is composed of two structurally distinct phases, both of which are metallic and super-conducting. One phase has a structure closely related to the stoichiometric oxygen-poor compound. The second shows a considerable amount of apical oxygen disorder, a large shift in NQR frequency {nu}{sub Q}, and a volume fraction which increases with cooling rate. The formation of the second phase below {minus}200K is indicative of the freezing Of CuO{sub 6} octahedral tilting. Abrupt shifts in {nu}{sub Q} above {Tc} were also observed for both phases, suggestive of a local structural anomaly or charge transfer to the Cu-O plane.

Reyes, A.P.; Ahrens, E.T.; Hammel, P.C.; Heffner, R.H.; Thompson, J.D.; Canfield, P.C.; Fisk, Z. (Los Alamos National Lab., NM (United States)); Schirber, J.E. (Sandia National Labs., Albuquerque, NM (United States))

1992-01-01

161

Determination of Soil Hydraulic Properties Using Magnetic Resonance Techniques and Classical Soil Physics Measurements  

NASA Astrophysics Data System (ADS)

Water and solute movement as any other transport processes through soil are influenced by the hydraulic properties of the soils. The heterogeneities of the soils imply heterogeneous spatial distribution of the hydraulic properties leading to heterogeneous distribution of soil water content. This may affects the water availability for plant growth, the groundwater contamination and nutrients losses within the root zone. The measurement techniques available today for the estimation of soil hydraulic parameters do not account for the heterogeneity of the sample and treat each measurement sample as a homogeneous representative volume. On the other side natural soils contain large heterogeneities mostly in terms of inclusions of different materials. Therefore the purpose of this study is to estimate soil hydraulic properties of a heterogeneous sample by combining classical multi-step-outflow (MSO) with magnetic resonance imaging (MRI) experiments. MSO experiments were performed on a sample filled with sand and sand-clay mixture in a coaxial structure. During each pressure application MRI images at 4.7 T (200 MHz) were recorded using a pure phase-encoding MRI sequence in order to provide information about the soil water content at specific locations within the coaxial sample. The recorded cumulative outflow and water content data were used as input data in the inversion of the MSO experiment. For the simulation and inversion of the MSO experiment we used the hydrological model HYDRUS-2D3D in which the initial hydraulic parameters of the two materials were estimated based on CPMG-T2 relaxation measurements on homogeneous sub-samples. The results show conclusively that the combination of the two MRI and MSO methods leads to a unique estimation of the hydraulic properties of two materials simultaneously.

Stingaciu, Laura R.; Weihermller, Lutz; Pohlmeier, Andreas; Stapf, Siegfried; Vereecken, Harry

2011-03-01

162

Korormicin insensitivity in Vibrio alginolyticus is correlated with a single point mutation of Gly-140 in the NqrB subunit of the Na(+)-translocating NADH-quinone reductase.  

PubMed

Na(+)-translocating NADH-quinone reductase (NQR) from the marine Vibrio alginolyticus is strongly inhibited by a new antibiotic korormicin. Korormicin specifically inhibits the Na(+)-dependent reaction of the NQR complex and acts as a purely non-competitive inhibitor for Q-1 with the inhibitor constant of 82 pM. Korormicin-resistant mutants were isolated from V. alginolyticus and the NQR complex was purified from a mutant KR2. Similar to 2-n-heptyl-4-hydroxyquinoline N-oxide (HQNO), korormicin acted as a purely noncompetitive inhibitor to the NQR complex from the mutant KR2, but the inhibitor constant increased to 8 microM, which is 10(5)-fold higher than that of the wild-type NQR complex. The inhibitor constant of HQNO, however, was only slightly affected by the acquisition of korormicin resistance. The spontaneous mutation was caused by a single mutation of G-422 to T-422 in the nucleotide sequence of the nqrB gene, which resulted in the conversion of Gly-140 to Val-140. Thus, Gly-140 seems to play an important role for the binding of korormicin to the NqrB subunit. The fact that korormicin is a purely noncompetitive inhibitor for Q-1 strongly supports the presence of one of Q-1 binding sites in the NqrB subunit, which also has a covalently bound FMN at Thr-235. PMID:12054467

Hayashi, Maki; Shibata, Naoaki; Nakayama, Yuji; Yoshikawa, Kazuhiro; Unemoto, Tsutomu

2002-05-15

163

Characterization technique of optical whispering gallery mode resonators in the microwave frequency domain for optoelectronic oscillators.  

PubMed

Optical Q factor measurements are performed on a whispering gallery mode (WGM) disk resonator using a microwave frequency domain approach instead of using an optical domain approach. An absence of hysteretic behavior and a better linearity are obtained when performing linewidth measurements by using a microwave modulation for scanning the resonances instead of the piezoelectric-based frequency tuning capability of the laser. The WGM resonator is then used to stabilize a microwave optoelectronic oscillator. The microwave output of this system generates a 12.48 GHz signal with -94 dBc/Hz phase noise at 10 kHz offset. PMID:22781250

Merrer, Pierre-Henri; Saleh, Khaldoun; Llopis, Olivier; Berneschi, Simone; Cosi, Franco; Conti, Gualtiero Nunzi

2012-07-10

164

[Principles and technique of magnetic resonance guided focused ultrasound surgery (MRgFUS) in the treatment of uterine fibroids].  

PubMed

Uterine fibroids are a significant source of morbidity for women of reproductive age, and can result in substantial symptoms affecting their quality of life. Definitive treatment has traditionally been a myomectomy, but increasingly women are not prepared to undergo such an invasive procedure for a benign and usually self-limiting condition. Focused ultrasound ablation is one of the least invasive treatment options outside medical therapy and does not require an anesthetic.Magnetic resonance guided focused ultrasound (MRgFUS) ablation combines therapy delivered by an ultrasound transducer with imaging guidance for therapy and thermal feedback provided by magnetic resonance imaging. This paper provides an overview of the MRgFUS technique, including a brief description of the treatment system, guidelines for selection of patients and follow-up, and a comparison with other treatment techniques. PMID:21894231

Vzquez-Lamadrid, Jorge; Fernndez-de Lara, Yeni; Carrasco-Choque, Analuz; Romero-Trejo, Cecilia; Cosme-Labarthe, Juan; Roldan-Valadez, Ernesto

165

Comparison of surface plasmon resonance spectroscopy and quartz crystal microbalance techniques for studying DNA assembly and hybridization  

Microsoft Academic Search

In this study we evaluate the strengths and weaknesses of surface plasmon resonance (SPR) spectroscopy and quartz crystal microbalance (QCM) technique for studying DNA assembly and hybridization reactions. Specifically, we apply in parallel an SPR instrument and a 5MHz QCM device with dissipation monitoring (QCM-D) to monitor the assembly of biotinylated DNA (biotin-DNA) on a streptavidin-modified surface and the subsequent

Xiaodi Su; Ying-Ju Wu; Wolfgang Knoll

2005-01-01

166

Measurement of Pulmonary Vascular Structure and Pulmonary Blood Distribution by Multidetector-Row Computed Tomography and Magnetic Resonance Imaging Techniques  

Microsoft Academic Search

\\u000a Pulmonary-based X-ray computed tomography (CT) and magnetic resonance (MR) imaging techniques have been developed for structural\\u000a and functional assessment of the lungs. CT methods, taking advantage of newer multidetector-row CT (MDCT) technology, provide\\u000a a means of quantitatively studying regional pulmonary perfusion (via iodine-based contrast agents) in conjunction with the\\u000a acquisition of highly detailed information regarding the lung parenchyma and vasculature

Sara K. Alford; Eric A. Hoffman

167

Fast resonance-detection technique for single-frequency operation of injection-seeded Nd:YAG lasers  

SciTech Connect

A new technique for maintaining single-frequency output from injection-seeded Nd:YAG lasers is described. It involves quickly sweeping the slave-cavity longitudinal-mode spectrum when the flash lamps have created a maximum population inversion. An interference signal is detected by fast electronics, and the Q switch is opened when the slave cavity is resonant with the injected field.

Henderson, S.W.; Yuen, E.H.; Fry, E.S.

1986-11-01

168

DSP microcontroller-based fuzzy control of a DC\\/DC parallel resonant converter using phase-shift PWM technique  

Microsoft Academic Search

Purpose To analyze the operating performance of an ac-dc-ac-dc PWM parallel resonant converter operating at lagging power factor mode controlled based on fuzzy logic control method. Design\\/methodology\\/approach A range of published works relevant to dc-ac-dc converters and their control methods based on PWM technique are evaluated and their limitations in converter output voltage control are indicated in the

?res ?skender; Y?ld?r?m tu?; H. Blent Ertan

2006-01-01

169

All-optical interconnection with wiring maintenance technique by integrated full-linear resonator  

NASA Astrophysics Data System (ADS)

We have proposed the all-optical interconnection, in which the photorefractive four wave mixing (FWM) is used as the core, by full-linear resonator (FR) with a beam splitter (BS) and a self-pumped phase conjugate mirror (CAT). The index grating of the FWM region inside the photorefractive crystal (PRC), which determines the connection pattern, was maintained by the rewriting effect of the input signal beam and the resonance beam between the CAT and the BS. But the power of the resonance beam was wasted by the optical reflection at the crystal surface of the CAT and the PRC. Therefore the rewriting effect of the connection pattern could not be obtianed sufficiently. In this report, we propose the integrated full-linear resonator (IFR), in which a self-pumped phase conjugation (SPPC) region and the FWM region are formed in one PRC, to solve this problem. Compared with the conventional FR, the power loss of the resonance beam by the optical reflection can be prevented and the resonance beam can be used efficiently for the maintenance of the connection pattern. We experiment on the 22 all-optical interconnection with the IFT by using BaTiO3 crystals and Ar+ laser. It is shown that the maintenance time of the connection pattern can be extended sufficiently by using IFR.

Mitasaki, Tokinobu; Okamoto, Atsushi; Honma, Satoshi

2003-08-01

170

Acoustic Techniques in Magnetic Resonance: Acoustic coupling to nuclear and electron spins is a measure of relaxation in paramagnetic systems.  

PubMed

In conclusion, I believe it fair to say that the marriage of ultrasonics and magnetic resonance holds promise of being a productive one. In the application of these disciplines to nuclear spins, little more has been done than to demonstrate the acoustic techniques and to apply them to a particular problem of quadrupolar coupling in the heavy alkali halides. Particularly promising is the extension of acoustic NMR techniques to bulk metals, to ferromagnetic crystals, and to the study of spin-lattice relaxation as a function of temperature. In the technique of phonon coupling to electron spins in paramagnetic materials, also, the reports to date have all been of a preliminary nature. Used in combination with the powerful new hypersonic technique of generating microwave acoustic waves, electron spin-phonon interaction measurements may help to resolve some of the present confusion regarding the mechanisms of spin-lattice relaxation in paramagnetic solids (29). PMID:17798054

Bolef, D I

1962-05-01

171

Ion cyclotron resonance ion trap measurements of energy relaxation in gas-phase ions: Three techniques compared for thiophenol ion  

SciTech Connect

Photodissociation measurements in the ICR (ion cyclotron resonance) ion trap were used to find the collisionless relaxation rate of thiophenol ions prepared with 2-3 eV of excess internal energy. Three techniques have been described previously that exploit the kinetic differences between one-photon and two-photon dissociation, and these three methods were applied and compared for this case. The two-light-pulse technique gave good data and a clear interpretation and was considered clearly the best method. The intensity-dependence technique gave good data but a less clear-cut interpretation, while the chopped-laser technique was only marginally useful for this slowly relaxing ion. It was concluded that about 0.3 s is required for excited thiophenol ion to relax from 2.5 to 0.8 eV of internal energy.

Faulk, J.D.; Dunbar, R.C. (Case Western Reserve Univ., Cleveland, OH (USA))

1989-11-16

172

Is it Possible to Detect Dendrite Currents Using Presently Available Magnetic Resonance Imaging Techniques?  

PubMed Central

The action currents of a dendrite, peripheral nerve or skeletal muscle create their own magnetic field. Many investigators have attempted to detect neural and dendritic currents directly using magnetic resonance imaging that can cause the phase of the spins to change. Our goal in this paper is to use the calculated magnetic field of a dendrite to estimate the resulting phase shift in the magnetic resonance signal. The field produced by a dense collection of simultaneously active dendrites may be just detectable under the most ideal circumstances, but in almost every realistic case the field cannot be detected using current MRI technology.

Jay, William I.; Wijesinghe, Ranjith S.; Dolasinski, Brain D.; Roth, Bradley J.

2013-01-01

173

Laser-frequency locking techniques for high-sensitivity strain measurements by high-birefringence fiber Bragg gratings and resonators  

NASA Astrophysics Data System (ADS)

A new approach to simultaneously interrogate orthogonal axes of single Fiber-Bragg-Gratings (FBGs) and FBG-Fabry Perot resonator sensors fabricated in linearly highly birefringent (HiBi) fibre is presented. Novel interrogation techniques of single Fiber-Bragg-Gratings (FBGs) and FBG-resonator sensors are presented. For a single FBG, we combined a laser-modulation technique to an electronic feedback loop that keeps the source always frequency locked to one peak of the sensor's reflected spectrum. Two different lasers, with orthogonally-polarized states, were adopted to monitor simultaneously both the "fast" and "slow" FBG peaks. The corresponding correction signals from the servo-loop outputs can be interpreted as strain or temperature induced on the FBG. Detection limits ranging from 1 nV/?Hz to 100 nV/?Hz, for axial dynamic and static deformations, respectively, and of 0.025 C/?Hz for temperature variations, are expected. A similar approach was developed for sub-p? resolution interrogation of an optical resonator made of a high-reflectivity FBG-pair, using the Pound-Drever-Hall (PDH) stabilization method..

Salza, M.; Gagliardi, G.; Di Maio, A.; Ferraro, P.; De Natale, P.; Chehura, E.; Tatam, R.

2007-07-01

174

A novel frequency measurement technique for quartz microbalance systems and other resonator-based sensor systems  

Microsoft Academic Search

This paper describes the operation and design of a simple, low cost period counting system based on a D flip-flop mixer, directly applicable to quartz microbalances and quartz resonator-based sensors. The architecture of the period counting system is based on measuring the period of a low frequency difference signal obtained by subtracting a high stability reference frequency from the unknown

I. Shankar; S. A. Morris; C. G. Hutchens

2002-01-01

175

Harmonic decomposition in PDE-based denoising technique for magnetic resonance electrical impedance tomography  

Microsoft Academic Search

Recent progress in magnetic resonance electrical impedance tomography (MREIT) research via simulation and biological tissue phantom studies have shown that conductivity images with higher spatial resolution and accuracy are achievable. In order to apply MREIT to human subjects, one of the important remaining problems to be solved is to reduce the amount of the injection current such that it meets

Byung Il Lee; Suk-Ho Lee; Tae-Seong Kim; Ohin Kwon; Eung Je Woo; Jin Keun Seo

2005-01-01

176

Automating micro cellular detection process using all-transparent microfluidic platform and surface plasmon resonance technique  

Microsoft Academic Search

This paper reports an automated polymer based microfluidic analysis system integrated with the surface plasmon resonance (SPR) biosensor for qualitatively monitoring of cell adhesion on the sensor surface. Micropumps, microchannels, and SPR biosensor were integrated into a single polymer (PMMA) based microfluidic system. The integrated system has been studied in its potential application in drugs discovery. An experiment, which is

Kin Fong Lei; Wing Cheung Law; Chi Lok Wong; Wen J. Li; Ho Pui Ho; Siu-Kai Kong; Chinlon Lin

2005-01-01

177

Hopping at the resonance frequency: A trajectory generation technique for bipedal robots with elastic joints  

Microsoft Academic Search

It is known that bipedal robots with passive compliant structures have obvious advantages over stiff robots, as they are able to handle the potential energy management. Therefore, this paper is aimed at presenting a jumping pattern generation method that takes advantage of this property via the utilization of the base resonance frequency, which is of special importance. To begin with,

Barkan Ugurlu; Jody A. Saglia; Nikos G. Tsagarakis; Darwin G. Caldwell

2012-01-01

178

Low-Cost and High-Q Millimeter-Wave Resonator Using Substrate Integrated Waveguide Technique  

Microsoft Academic Search

A substrate integrated waveguide (SIW) cavity directly coupled to a planar circuit, i.e. microstrip line or coplanar waveguide, is presented. Different coupling topologies and coupling probes are discussed. Empirical equations to predict the resonance frequencies of the cavity are provided. A temperature stability coupling topology were fabricated and measured. Finally, as an example of potential applications, a filter using two

Y. Cassivi; L. Perregrini; K. Wu; G. Conciauro

2002-01-01

179

Development of a Mounting Technique for Quartz Resonators Using Microcircuit Interconnect Technologies.  

National Technical Information Service (NTIS)

This report describes the work done in developing an interconnect capability for attaching to a tungsten metallized Al sub 2 O sub 3 package a mounting clip used to hold small (0.051 mm thick x 6.35 mm in diameter) quartz crystal resonators in a nearly st...

D. W. Bushmire E. L. Chavez

1976-01-01

180

Manifold Learning Techniques in Image Analysis of High-dimensional Diffusion Tensor Magnetic Resonance Images  

Microsoft Academic Search

Diffusion Tensor magnetic resonance imaging (DT-MRI) provides a comprehensive characterization of white matter (WM) in the brain and therefore, plays a crucial role in the investigation of diseases in which WM is suspected to be compromised such as multiple sclerosis and neuropsychiatric disorders like schizophrenia. However changes induced by pathology may be subtle and affected regions of the brain can

Parmeshwar Khurd; Sajjad Baloch; Ruben C. Gur; Christos Davatzikos; Ragini Verma

2007-01-01

181

A Technique for Regional Analysis of Femorotibial Cartilage Thickness Based on Quantitative Magnetic Resonance Imaging  

Microsoft Academic Search

The objective of this work was to develop a methodology for measuring cartilage thickness in anatomically based subregions in the tibial and in the central weight-bearing femoral cartilage from magnetic resonance (MR) images. The tibial plateau was divided into a central area of the total subchondral bone area (tAB), and anterior, posterior, internal, and external subregions surrounding it. In the

Wolfgang Wirth; Felix Eckstein

2008-01-01

182

A novel technique for multilevel optimal magnetic resonance brain image thresholding using bacterial foraging  

Microsoft Academic Search

The present paper proposes a novel optimal multilevel thresholding algorithm for brain magnetic resonance image segmentation. This optimization algorithm, employed for image histogram-based thresholding, is based on a relatively recently proposed evolutionary approach, namely, bacterial foraging. Originally proposed towards the fag end of last millennium, bacterial foraging is emerging as a strong contender for distributed control and optimization. The utility

Madhubanti Maitra; Amitava Chatterjee

2008-01-01

183

Sodium and potassium salts of dichloroisocyanuric acid and their hydrates as antimicrobials agents studied by 35Cl-NQR spectroscopy and DFT calculations  

NASA Astrophysics Data System (ADS)

The electronic structure of dichloroisocyanuric acid derivatives was analysed by 35Cl-NQR spectroscopy and DFT calculations. Here we concentrate our attention on three different factors: type of metallic substituent (sodium and potassium), temperature of the sample (liquid nitrogen and room) and degree of hydration (an amount of water molecules attached to analysed compounds). In particular, all the variations in 35Cl-NQR frequencies upon hydration of salts containing sodium and potassium ions are explained as a consequence of H-bonds formation and accompanied effects of charge redistribution. Our studies can be useful in searching for the derivatives of dichloroisocyanuric acid revealing higher antimicrobial activity.

Walczak, A.; Brycki, B.; Kaczmarek, M.; Poleshchuk, O. Kh.; Ostafin, M.; Nogaj, B.

2006-06-01

184

Determination of human complement factor C4 using resonance light-scattering technique with sodium dodecylbenzene sulphonate probe  

NASA Astrophysics Data System (ADS)

Based on the interaction between human complement factor C4 (human C4) and sodium dodecylbenzene sulphonate (SDBS) and the resonance light-scattering (RLS) technique, a highly sensitive assay for human C4 using resonance light-scattering technique was developed. At pH 2.8 Na 2HPO 4-citric acid buffer solution, the RLS intensities of SDBS system at 283, 503 and 600 nm were obviously enhanced in the presence of human C4. The effects of surfactant, pH, incubation time, concentration of SDBS and foreign substances on the enhanced RLS intensity of system were investigated. Under the optimum conditions, the enhanced RLS intensity is directly proportional to the concentration of human C4 in the range of (0.5-120) 10 -6 g l -1 and the linear regression equation was obtained with high correlation coefficient. This RLS technique was applied to the determination of human C4 in some synthetic samples with good recovery. Moreover, it was found that the electrostatic interaction is the main binding force between SDBS and human C4.

Gao, Dejiang; Tian, Yuan; Ding, Lan; Liang, Fanghui; Bi, Shuyun; Chen, Yanhua; Yu, Aimin; Zhang, Hanqi

2006-05-01

185

Development of a Magnetic Resonance Imaging Technique for Measuring Emulsion Coalescence  

NASA Astrophysics Data System (ADS)

The kinetics of emulsion coalescence determine emulsion stability and rheology. In an opaque, concentrated emulsion, conventional optical methods for monitoring the droplet size distribution are often impractical, and cannot distinguish between flocculation and coalescence. Nuclear magnetic resonance (NMR) is uniquely suited to measuring droplet size distributions by observing restricted diffusion, which is unaffected by flocculation. We aim to quantify the effect of shear flow on coalescence of a concentrated emulsion. We have constructed a combined annular Couette flow cell and magnetic resonance imaging probe. We have extracted the droplet size distribution in a quiescent emulsion from restricted diffusion curves and shown that the NMR method produces nearly quantitative agreement with light scattering measurements. Data from monitoring the droplet size distribution, droplet concentration and velocity profiles over time in the flowing emulsion system will be presented.

Powell, Robert; D"Avila, Marcos; Shapley, Nina; Walton, Jeffrey; Phillips, Ronald; Dungan, Stephanie

2000-11-01

186

Advances in fiber-optic based UV resonance Raman spectroscopy techniques for anatomical and physiological investigations  

Microsoft Academic Search

Ultraviolet resonance Raman spectroscopy (UVRRS) is becoming a very popular spectroscopic method for bioanalytical investigations due to its high sensitivity, lack of fluorescence, and suitability for use in aqueous solutions. We have made a number of technological advances, especially the development of fiber-optic-b ased technologies, which permit the performance of remote\\/in-sit u UVRRS measurements. We will be reporting on improved

H. Georg Schulze; Christopher J. Barbosa; L. Shane Greek; Robin F. B. Turner; Charles A. Haynes; Michael W. Blades

187

Determination for micro amounts of nucleic acids by a resonance light scattering technique with dequalinium chloride  

Microsoft Academic Search

Based on the strong enhancement effect of nucleic acids on resonance light scattering of dequalinium chloride, the determination method for micro amounts of nucleic acids has been developed. Under the experimental conditions (5.010?5 mol l?1 dequalinium, pH 7.0, at room temperature) the linear range of this assay is 0.0410.0 ?g ml?1 for calf thymus DNA and fish sperm DNA, and

Zheng-Ping Li; Ke-An Li; Shen-Yang Tong

2001-01-01

188

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

NASA Astrophysics Data System (ADS)

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

Seliger, J.; agar, V.

2008-07-01

189

Resonator micro optic gyro with double phase modulation technique using an FPGA-based digital processor  

NASA Astrophysics Data System (ADS)

Experiments on resonator micro-optic gyro (RMOG) with a digital proportional integral (PI) feedback scheme are performed. In this experimental setup, the key rotation sensing element is a polarization maintaining silica waveguide ring resonator (WRR) with a ring length of 7.9 cm and a diameter of 2.5 cm. A good linearity of 0.0015% over a wide range of 2 104 /s can be achieved for the RMOG theoretically. The optimal digital PI feedback scheme is adopted in the frequency servo loop to reduce the reciprocal frequency fluctuations due to the WRR resonance frequency and laser frequency drifts. Residual equivalent input fluctuation can be reduced as low as 0.03 /s/?Hz based on the optimal digital PI feedback scheme, which is close to the shot noise limited spectral density 0.02 /s/?Hz of the RMOG with the input optical power of 0.2 mW. Relationship between RMOG output signal and angular rate is obtained from 0.1 /s to 5 /s. The standard deviation of the residuals between RMOG output results and linear fit curve is 0.066 /s. For an integration of the processing circuit, all the processing circuit is implemented by a field programmable gate array (FPGA) instead of instruments. The output of this digitalized RMOG is obtained over a range of 550 /s. The linearity of this digitalized RMOG is 0.0169%.

Jin, Zhonghe; Zhang, Guhong; Mao, Hui; Ma, Huilian

2012-03-01

190

New speckle control technique using high-speed electro-optic modulators with resonant electrode and polarization-reversed structures  

NASA Astrophysics Data System (ADS)

We propose a new technique for reducing speckle noise in laser displays utilizing a high-speed optical phase modulator for expanding the laser beam spectrum. By adopting standing-wave resonant electrodes and polarization-reversed structures to LiTaO3 electro-optic modulators, high-efficiency phase modulation with a large modulation index at high microwave frequency ranges is obtainable for different color laser beams at the same time. This enables us to expand laser spectra to over 100 GHz and reduce speckle noise. The device design, fabrication, and experimental demonstration for speckle control are reported.

Murata, Hiroshi; Furusho, Keita; Yamamoto, Kazuhisa; Okamura, Yasuyuki

2012-11-01

191

Single-spin fluid, spin gap, and [ital d]-wave pairing in YBa[sub 2]Cu[sub 4]O[sub 8]: A NMR and NQR study  

SciTech Connect

We present results of [sup 17]O and [sup 63,65]Cu nuclear magnetic resonance (NMR) and nuclear quadrupolar resonance (NQR) studies in the normal and superconducting state of the 82-K superconductor YBa[sub 2]Cu[sub 4]O[sub 8]. The various components of the Cu and O Knight-shift tensors show strong but similar temperature dependences over the temperature range from 8.5 to 300 K in both the CuO[sub 2] planes and the chains, supporting the picture that there is only one spin component in the planes and the chains, although with different susceptibilities. The oxygen data obey the Korringa relation. This may be interpreted as Fermi-liquid behavior of the electronic system far away from the antiferromagnetic wave vector. The temperature dependence of both the planar Cu and O shift tensors and the planar Cu spin-lattice relaxation rate suggest the opening of a pseudo-spin-gap well above [ital T][sub [ital c

Bankay, M.; Mali, M.; Roos, J.; Brinkmann, D. (Physik-Institut, Universitaet Zuerich, 8057 Zuerich (Switzerland))

1994-09-01

192

Heavy Fermion Superconductor Ce2PdIn8 studied by 115In Nuclear Quadrupole Resonance  

NASA Astrophysics Data System (ADS)

We have performed nuclear quadrupole resonance (NQR) measurements on a recently-discovered heavy-fermion superconductor Ce2PdIn8 with superconducting critical temperature Tc = 0.64 K. Below coherent temperature Tcoh ~ 30 K, the spin-lattice relaxation rate 1/T1 decreases with decreasing temperature T and is proportional to T1/2 between Tc and Tcoh. This is clearly different from the Fermi-liquid behavior in which the T dependence is proportional to T, and indicates that Ce2PdIn8 is located on the verge of antiferromagnetic quantum critical point from the view point of the NQR. Below Tc, 1/T1 shows no coherence peak and is proportional to T3. This is clear evidence for the realization of unconventional superconductivity with line nodes in this compound.

Fukazawa, H.; Nagashima, R.; Shimatani, S.; Kohori, Y.; Kaczorowski, D.

2013-07-01

193

Neutron Resonance Transmission Analysis (NRTA): A Nondestructive Assay Technique for the Next Generation Safeguards Initiatives 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

194

Poly(3-hexylthiophene) self-assembled monolayer based cholesterol biosensor using surface plasmon resonance technique  

Microsoft Academic Search

Cholesterol oxidase (ChOx) has been covalently immobilized onto 1-fluoro-2-nitro-4-azidobenzene (FNAB) modified poly-(3-hexylthiophene) (P3HT) self-assembled monolayer (SAM) onto gold coated glass plates. These ChOx\\/FNAB\\/P3HT\\/Au bio-electrodes have been characterized using contact angle (CA) measurements, UVvis spectroscopy, electrochemical impedance technique, cyclic voltammetric technique and atomic force microscopic (AFM) technique, respectively. The ChOx\\/FNAB\\/P3HT\\/Au bio-electrodes were utilized for the estimation of cholesterol concentration in standard

Sunil K. Arya; Pratima R. Solanki; S. P. Singh; K. Kaneto; Manoj K. Pandey; Monika Datta; Bansi D. Malhotra

2007-01-01

195

Study of the pygmy dipole resonance in 94Mo using the (?,???) coincidence technique  

NASA Astrophysics Data System (ADS)

The (?,???) reaction at E?=136 MeV was used to study the electric dipole response in the open-shell vibrational nucleus 94Mo below the neutron-separation threshold. The coincidence experiment has been performed at the Kernfysisch Versneller Instituut in Groningen, The Netherlands, exploiting the Big-Bite Spectrometer and an array of large volume High-Purity Germanium (HPGe) detectors. Due to the excellent energy resolution and high selectivity to transitions stemming from the pygmy dipole resonance, singles ?-scattering cross sections could be determined for individual electric dipole excitations between 4 and 8 MeV. For three of the excited low-lying J?=1? states in 94Mo a ?-decay branch into the J?=21+ state could be observed.The experiment extends the systematic studies of the pygmy dipole resonance by real-photon scattering (?,??) experiments and (?,???) experiments. Recently, a (?,??) experiment on 94Mo was performed at the Darmstadt High-Intensity Photon Setup at the S-DALINAC in Darmstadt, Germany, permitting the comparison of B(E1)? strength distribution and ?-scattering cross sections.

Derya, V.; Endres, J.; Elvers, M.; Harakeh, M. N.; Pietralla, N.; Romig, C.; Savran, D.; Scheck, M.; Siebenhhner, F.; Stoica, V. I.; Wrtche, H. J.; Zilges, A.

2013-05-01

196

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.

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

2011-01-01

197

Sensitive Determination of Proteins with Naphthol Green B by Resonance Light Scattering Technique  

NASA Astrophysics Data System (ADS)

A new quantitative determination method for trace proteins using naphthol green B (NGB) by resonance light scattering (RLS) spectroscopy has been developed. The method is based on the interaction of protein and NGB at pH 3.00, which causes a substantial enhancement of the resonance scattering signal of NGB in the wavelength range 300-550 nm with the maximum RLS at 392.0 nm. Under optimum conditions, the linear range is 0.010-28.2 ?g/ml for bovine serum albumin (BSA) and 0.010-31.3 ?g/ml for human serum albumin (HSA). The detection limits (S/N=3) are 8.2 ng/ml for BSA and 7.9 ng/ml for HSA, respectively. There is little or no interference from amino acids, most of the metal ions, or other coexisting substances. The easy-to-use method, with high sensitivity and good reproducibility, was satisfactorily applied to the determination of total protein in human serum samples. The determination results for human serum samples are identical to those provided by clinical physicians.

Gu, B.; Zhong, H.; Li, X.-M.; Wang, Y.-Z.; Ding, B.-C.; Cheng, Z.-P.; Zhang, L.-L.; Li, S.-P.; Yao, C.

2013-09-01

198

Radio-frequency tunable atomic magnetometer for detection of solid-state NQR  

Microsoft Academic Search

We constructed a potassium atomic magnetometer which resonantly detects rf magnetic fields with subfemtotesla sensitivity. The resonance frequency is set by the Zeeman resonance of the potassium atoms in a static magnetic field applied to the magnetometer cell. Strong optical pumping of the potassium atoms into a stretched state reduces spin-exchange broadening of the Zeeman resonance, resulting in relatively small

S.-K. Lee; K. L. Sauer; S. J. Seltzer; O. Alem; M. V. Romalis

2007-01-01

199

A novel time resolved resonance Raman technique - applications in correlated systems  

NASA Astrophysics Data System (ADS)

In many modern materials the functionality of a system can be observed by studying the order parameters in the time domain. Here, we present a time resolved pump probe resonance Raman system that allows to study order parameters in an energy range from 5 meV to several eV and in a time domain from 1 ps to several ns. Due to our fully achromatic, all reflective Raman spectrometer, [1] we are able to combine pump and probe beams ranging in energy from the near infrared to the deep ultraviolet. We show exemplary measurements on the melting process in charge order Manganites (La0.5Ca0.5MnO3) as well as studies on the temporal evolution of the superconducting parameter in high-Tc cuprates.[1] B. Schulz et al, Rev. Sci. Instrum. 76, 73107 (2005).

Schulz, B.; Mahns, I.; Goos, A.; Saichu, P.; Binder, S.; Singer, S. G.; Rusydi, A.; Ruebhausen, M.; Cheong, S.-W.; Guptasarma, P.

2008-03-01

200

Improved coupling technique of ultracompact ring resonators in silicon-on-insulator technology.  

PubMed

In order to improve the coupling coefficient between a bus waveguide and a bent waveguide of an ultracompact microring to obtain the critical coupling, a design using a bent bus waveguide with reduced width is provided to maintain a better phase matching and increase the coupling. A full vectorial finite difference model, specifically suited for high index contrast and smaller size waveguides, for example, a waveguide in the silicon-on-insulator (SOI) technology, is developed. As a validation, the straight and bent waveguides are simulated using this model, whose results are compared with the results deduced from the measurement results of the ultracompact ring resonators in SOI technology. Also, the model solver is performed to simulate the design, and an experiment is implemented to testify the design. PMID:22858963

Fan, Guofang; Orbtchouk, Regis; Han, Bing; Liu, Xinhou; Zhen, Zhen

2012-07-20

201

Synthesis and characterization of superparamagnetic nanoparticles coated with carboxymethyl starch (CMS) for magnetic resonance imaging technique  

Microsoft Academic Search

Magnetic nanoparticles have been proposed for use as biomedical purposes to a large extent for several years. The development of techniques that could selectively deliver drug molecules to the diseased site, without a concurrent increase in its level in healthy tissues, is currently one of the most active areas of cancer research. The conjugate carboxymethyl starch (CMS)\\/SPIO nanoparticles were prepared

Mohammad Reza Saboktakin; Abel Maharramov; Mohammad Ali Ramazanov

2009-01-01

202

Detection of Gas Phase Free Radicals by Electron Spin Resonance Spin Trapping Techniques.  

National Technical Information Service (NTIS)

It was demonstrated that gas phase free radicals can be detected by spin trapping techniques i.e. free radicals present in a carrier gas react with solid phenyl t-butyl nitrone (spin trap) to give nitroxides which give esr spectra characteristic of the ga...

E. G. Janzen J. L. Gerlock

1969-01-01

203

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

204

Determination of proteins with tetracarboxy manganese(II) phthalocyanine by resonance light scattering technique.  

PubMed

A novel method for the determination of proteins by using tetracarboxy manganese(II) phthalocyanine (MnC4Pc) as a resonance light scattering (RLS) probe has been developed. At pH 3.0 Britton-Robinson (B-R) buffer solution, the RLS intensity of MnC4Pc at 385 nm is greatly enhanced in the presence of proteins. The effects of pH, reaction time, concentration of MnC4Pc and interfering substances on the enhanced RLS intensity are investigated, respectively. Under optimal conditions, the linear ranges of the calibration curves are 0-2.00 microg mL(-1) for bovine serum albumin (BSA) and human serum albumin (HSA), 0.0-1.75 microg mL(-1) for human-IgG and ovalbumin, with a detection limit of 16.37 ng mL(-1) BSA, 17.62 ng mL(-1) HSA, 19.41 ng mL(-1) human-IgG and 20.72 ng mL(-1) ovalbumin. The method has been applied to the determination of total proteins in human serum samples collected from a hospital and the results are in good agreement with those reported by the hospital. PMID:18450504

Tang, Ning-Li; Peng, Jin-Yun

2008-03-26

205

Elucidation of fundamental properties of helium in metals by nuclear magnetic resonance techniques  

SciTech Connect

The nuclear magnetic resonance (NMR) properties of very high density {sup 3}He in metals are discussed in the context of the corresponding properties in relatively high density bulk {sup 3}He. In particular, the effects of the {sup 3}He diffusion on the contribution of the {sup 3}He-{sup 3}He dipolar interaction to the lineshape and to the spin-lattice relaxation parameter (T{sub 1}) are described. It is shown that the temperature dependence of the lineshape and of T{sub 1} are independent sources of information about helium density and also about helium diffusivity. Moreover, T{sub 1} is shown to be a sensitive indicator of melting transitions in bulk {sup 3}He. Palladium tritide is presented as a model system for NMR studies of {sup 3}He in metals. Experimental NMR studies of this system reveal behavior analogous to what has been observed for bulk helium. Evidence for a {sup 3}He phase transition near 250 K is provided by the temperature dependence of T{sub 1}. Assuming this to be a melting transition, a density is obtained from the bulk helium EOS that is in good agreement with theory and with swelling measurements on related metal tritides. {sup 3}He NMR measurements have also provided information about the density distribution, helium diffusivity, and mean bubble size in palladium tritide. 22 refs., 8 figs.

Abell, G.C.

1990-01-01

206

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; Garca-Rubio, Ins.; Gehring, Andreas U.

2012-10-01

207

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

208

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.; Graa, M. P. F.; Sobolev, N. A.; Costa, F. M.; Monteiro, T.

2012-09-01

209

Resonance light scattering technique as a new tool to determine the binding mode of anticancer drug oridonin to DNA.  

PubMed

In this study, a sensitive and reliable assay has been developed to determine the binding mode of oridonin to DNA in vitro using resonance light scattering (RLS) technique. The binding mode of ORI with DNA has been confirmed by measuring the changes of RLS intensity under different pH and ionic strength. It is the ORI that is intercalated into the double helix DNA to destroy its template function and inhibit the synthesis of DNA. Moreover, the RLS assay result was validated by seasoned vitro methods. The proposed RLS assay is not only an unprecedented one for primarily determine the binding mode of oridonin to DNA, but also a simple, sensitive, objective and straightforward method for the detection of ORI. PMID:23827178

Chen, Zhanguang; Wang, Zhen; Chen, Junhui; Chen, Xi; Wu, Jiahui; Wu, Yanyu; Liang, Jieyao

2013-06-14

210

A systematic review of brain frontal lobe parcellation techniques in magnetic resonance imaging.  

PubMed

Manual volumetric measurement of the brain's frontal lobe and its subregions from magnetic resonance images (MRIs) is an established method for researching neural correlates of clinical disorders or cognitive functions. However, there is no consensus between methods used to identify relevant boundaries of a given region of interest (ROI) on MRIs, and those used may bear little relation to each other or the underlying structural, functional and connective architecture. This presents challenges for the analysis and synthesis of such results. We therefore performed a systematic literature review to highlight variations in the anatomical boundaries used to measure frontal regions, contextualised by up-to-date evidence from histology, hodology and neuropsychology. We searched EMBASE and MEDLINE for studies in English reporting three-dimensional boundaries for manually delineating the brain's frontal lobe or sub-regional ROIs from MRIs. Exclusion criteria were: exclusive use of co-ordinate grid systems; insufficient detail to allow method replication; publication in grey literature only. Papers were assessed on quality criteria relating to bias, reproducibility and protocol rationale. There was a large degree of variability in the three-dimensional boundaries of all regions used by the 208 eligible papers. Half of the reports did not justify their rationale for boundary selection, and each paper met on average only three quarters of quality criteria. For the frontal lobe and each subregion (frontal pole, anterior cingulate, dorsolateral, inferior-lateral, and orbitofrontal) we identified reproducible methods for a biologically plausible target ROI. It is hoped that this synthesis will guide the design of future volumetric studies of cerebral structure. PMID:23474540

Cox, Simon R; Ferguson, Karen J; Royle, Natalie A; Shenkin, Susan D; Macpherson, Sarah E; Maclullich, Alasdair M J; Deary, Ian J; Wardlaw, Joanna M

2013-03-10

211

Can the electron magnetic resonance (EMR) techniques measure the crystal (ligand) field parameters?  

NASA Astrophysics Data System (ADS)

In this paper, the question posed in the title is critically examined on the basis of the available literature evidence implying the positive answer. The distinction between, on the one hand, the actual crystal field (CF) or equivalently ligand field (LF) related quantities and, on the other hand, the actual zero-field splitting (ZFS) or equivalently fine structure (FS) quantities, is elucidated. The origin and possible roots of the incorrect terminology consisting in mixing up the two physically distinct quantities at different levels are examined. Aspects concerning Hamiltonians, parameters, energy level splitting, and nature of the operators involved are taken into account. Problems with the various notations for the operators and parameters used in the electron magnetic resonance (EMR) area are also identified and reviewed. A large number of cases of incorrect terminology and other inconsistencies identified in the course of a comprehensive literature survey are analyzed and systematically classified. Implications of the confusion in question, which go beyond the simple semantic issues, are discussed. The results of the survey reveal that the two most serious categories of this confusion lead to misinterpretation of the experimental EMR data. Several examples of serious misinterpretations found in the books, reviews, and original papers are discussed. The incorrect terminology contributes also to misleading keyword classifications of papers in journals as well as references in scientific literature databases. Thus, the database searches may produce unreliable outcomes. Examples of such outcomes are also shown. It is concluded that, in order to prevent further proliferation of the incorrect terminology and thus to increase reliability of the published EMR data, a concerted effort within the EMR community is indispensable. Various ways in this regard at the international level are suggested.

Rudowicz, C.; Sung, H. W. F.

2001-07-01

212

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 -15C. 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

213

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 12mm) 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

2013-06-10

214

Phosphorus nuclear magnetic resonance: a non-invasive technique for the study of muscle bioenergetics during exercise  

SciTech Connect

Phosphorus nuclear magnetic resonance (/sup 31/P NMR) spectroscopy is a non-destructive analytical laboratory technique that, due to recent technical advances, has become applicable to the study of high-energy phosphate metabolism in both animal and human extremity muscles (in vivo). /sup 31/P NMR can assay cellular phosphocreatine, ATP, inorganic phosphate, the phosphorylated glycolytic intermediates, and intra-cellular pH in either resting or exercising muscle, in a non-invasive manner. NMR uses non-perturbing levels of radio-frequency energy as its biophysical probe and can therefore safely study intact muscle in a repeated fashion while exerting no artifactual influence on ongoing metabolic processes. Compared with standard tissue biopsy and biochemical assay techniques, NMR possesses the advantages of being non-invasive, allowing serial in situ studies of the same tissue sample, and providing measurements of only active (unbound) metabolites. NMR studies of exercising muscle have yielded information regarding fatigue mechanisms at the cellular level and are helping resolve long-standing questions regarding the metabolic control of glycolysis, oxidative phosphorylation, and post-exercise phosphocreatine re-synthesis. NMR is also being utilized to measure enzymatic reaction rates in vivo. In the near future, other forms of NMR spectroscopy may also permit the non-invasive measurement of tissue glycogen and lactate content. 75 references.

Sapega, A.A.; Sokolow, D.P.; Graham, T.J.; Chance, B.

1987-08-01

215

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

216

Compositional study of silicon oxynitride thin films deposited using electron cyclotron resonance plasma-enhanced chemical vapor deposition technique  

SciTech Connect

We have used backscattering spectrometry and {sup 15}N({sup 1}H,{alpha},{gamma}){sup 12}C nuclear reaction analysis techniques to study in detail the variation in the composition of silicon oxynitride films with deposition parameters. The films were deposited using 2.45 GHz electron cyclotron resonance plasma-enhanced chemical vapor deposition (PECVD) technique from mixtures of precursors argon, nitrous oxide, and silane at deposition temperature 90 deg. C. The deposition pressure and nitrous oxide-to-silane gas flow rates ratio have been found to have a pronounced influence on the composition of the films. When the deposition pressure was varied for a given nitrous oxide-to-silane gas flow ratio, the amount of silicon and nitrogen increased with the deposition pressure, while the amount of oxygen decreased. For a given deposition pressure, the amount of incorporated nitrogen and hydrogen decreased while that of oxygen increased with increasing nitrous oxide-to-silane gas flow rates ratio. For nitrous oxide-to-silane gas flow ratio of 5, we obtained films which contained neither chemically bonded nor nonbonded nitrogen atoms as revealed by the results of infrared spectroscopy, backscattering spectrometry, and nuclear reaction analysis. Our results demonstrate the nitrogen-free nearly stoichiometric silicon dioxide films can be prepared from a mixture of precursors argon, nitrous oxide, and silane at low substrate temperature using high-density PECVD technique. This avoids the use of a hazardous and an often forbidden pair of silane and oxygen gases in a plasma reactor.

Baumann, H.; Sah, R.E. [Institut fuer Kernphysik, J.W. Goethe University, August-Euler-Strasse 6, 60486 Frankfurt (Germany); Fraunhofer Institute for Applied Solid State Physics, Tullastr. 72, 79108 Freiburg (Germany)

2005-05-01

217

Phase stability in fMRI time series: effect of noise regression, off-resonance correction and spatial filtering techniques.  

PubMed

Although the majority of fMRI studies exploit magnitude changes only, there is an increasing interest regarding the potential additive information conveyed by the phase signal. This integrated part of the complex number furnished by the MR scanners can also be used for exploring direct detection of neuronal activity and for thermography. Few studies have explicitly addressed the issue of the available signal stability in the context of phase time-series, and therefore we explored the spatial pattern of frequency specific phase fluctuations, and evaluated the effect of physiological noise components (heart beat and respiration) on the phase signal. Three categories of retrospective noise reduction techniques were explored and the temporal signal stability was evaluated in terms of a physiologic noise model, for seven fMRI measurement protocols in eight healthy subjects at 3T, for segmented CSF, gray and white matter voxels. We confirmed that for most processing methods, an efficient use of the phase information is hampered by the fact that noise from physiological and instrumental sources contributes significantly more to the phase than to the magnitude instability. Noise regression based on the phase evolution of the central k-space point, RETROICOR, or an orthonormalized combination of these were able to reduce their impact, but without bringing phase stability down to levels expected from the magnitude signal. Similar results were obtained after targeted removal of scan-to-scan variations in the bulk magnetic field by the dynamic off-resonance in k-space (DORK) method and by the temporal off-resonance alignment of single-echo time series technique (TOAST). We found that spatial high-pass filtering was necessary, and in vivo a Gaussian filter width of 20mm was sufficient to suppress physiological noise and bring the phase fluctuations to magnitude levels. Stronger filters brought the fluctuations down to levels dictated by thermal noise contributions, and for 62.5mm(3) voxels the phase stability was as low as 5 mrad (0.27). In conditions of low SNR(o) and high temporal sampling rate (short TR); we achieved an upper bound for the phase instabilities at 0.0017 ppm, which is close to the dHb contribution to the GM/WM phase contrast. PMID:22079450

Hagberg, Gisela E; Bianciardi, Marta; Brainovich, Valentina; Cassara, Antonino Mario; Maraviglia, Bruno

2011-11-04

218

Direct measurement of the accumulation and mitochondrial conversion of nitric oxide within Chinese hamster ovary cells using an intracellular electron paramagnetic resonance technique  

Microsoft Academic Search

We have developed an electron paramagnetic resonance (EPR) method for the nondestructive detection and quantification of intracellular NO in real time. Based upon this technique, we have obtained evidence for the metabolism of this bioregulatory molecule by mitochondria. Line-broadening of the EPR signal of a coal derivative, fusinite, was calibrated as a function of NO concentration in aqueous solution. The

R. B. Clarkson; S. W. Norby; A. Smirnov; S. Boyer; N. Vahidi; R. W. Nims; D. A. Wink

1995-01-01

219

NQR study of local structures and cooling rate dependent superconductivity in La{sub 2}CuO{sub 4+{delta}}  

SciTech Connect

Structural properties of oxygen-annealed polycrystals of La{sub 2}CuO{sub 4 + {delta}} ({delta}{approximately}0.03) have been studied using {sup 139}La NQR spectroscopy. Superconducting critical temperatures were found to depend on the rate of cooling through a narrow temperature range at about 195K. Preliminary analysis of the {sup 139}La NQR spectra suggest that the oxygen-rich phase-separated region is composed of two structurally distinct phases, both of which are metallic and super-conducting. One phase has a structure closely related to the stoichiometric oxygen-poor compound. The second shows a considerable amount of apical oxygen disorder, a large shift in NQR frequency {nu}{sub Q}, and a volume fraction which increases with cooling rate. The formation of the second phase below {minus}200K is indicative of the freezing Of CuO{sub 6} octahedral tilting. Abrupt shifts in {nu}{sub Q} above {Tc} were also observed for both phases, suggestive of a local structural anomaly or charge transfer to the Cu-O plane.

Reyes, A.P.; Ahrens, E.T.; Hammel, P.C.; Heffner, R.H.; Thompson, J.D.; Canfield, P.C.; Fisk, Z. [Los Alamos National Lab., NM (United States); Schirber, J.E. [Sandia National Labs., Albuquerque, NM (United States)

1992-10-01

220

Irreversible change in the T1 temperature dependence with thermal dose using the proton resonance frequency-T1 technique.  

PubMed

Denaturation of macromolecules within the tissues is believed to be the major factor contributing to the damage of tissues upon hyperthermia. As a result, the value of the spin-lattice relaxation time T1 of the tissue water, which is related to the translational and rotational rates of water, represents an intrinsic probe for investigating structural changes in tissues at high temperature. Therefore, the goal of this work is to investigate whether the simultaneous measurement of temperature and T1 using a hybrid proton resonance frequency (PRF)-T1 measurement technique can be used to detect irreversible changes in T1 that might be indicative of tissue damage. A new hybrid PRF-T1 sequence was implemented based on the variable flip angle driven-equilibrium single-pulse observation (DESPOT)1 method from a standard three dimensional segmented echo-planar imaging sequence by alternating two flip angles from measurement to measurement. The structural changes of the heated tissue volumes were analyzed based on the derived T1 values and the corresponding PRF temperatures. Using the hybrid PRF-T1 technique, we demonstrate that the change of spin lattice relaxation time T1 is reversible with temperature for low thermal dose (thermal dose ? 240 cumulative equivalent minutes [CEM] 43C) and irreversible with temperature after significant accumulation of thermal dose in ex vivo chicken breast tissue. These results suggest that the hybrid PRF-T1 method may be a potentially powerful tool to investigate the extent and mechanism of heat damage of biological tissues. PMID:22576265

Diakite, Mahamadou; Payne, Allison; Todd, Nick; Parker, Dennis L

2012-05-10

221

A novel curcumin assay with the metal ion Cu (II) as a simple probe by resonance light scattering technique  

NASA Astrophysics Data System (ADS)

A fantastic resonance light scattering (RLS) enhancement phenomenon was found when the interaction between the metal ion Cu (II) and a natural antioxidant curcumin (C 21H 20O 6) occurred in certain conditions. Based on this phenomenon, a novel and convenient assay of curcumin was developed and successfully applied on the determination of curcumin in human urine samples. This assay applied the RLS technique with a common metal ion Cu (II) as the spectral probe. In the pH range of 6.5-7.5, the interaction between Cu (II) and curcumin occurred and the weak RLS intensity of Cu (II) was greatly enhanced by curcumin. The maximum peak was located at 538.5 nm. Under the optimum conditions, the enhanced RLS intensity was proportional to the concentration of curcumin ranging from 0.4 to 60 ?g ml -1 with the detection limit of 0.07 ?g ml -1. The synthetic and human urine samples were determined satisfactorily. Good recoveries (98.8-102.5%) were obtained in the determination of urine samples, which proved that the assay proposed was reliable and applicable in the determination of curcumin in body fluid. In this work, the RLS and fluorescence spectral characteristics of the chemicals, the optimum conditions of the reaction and the influencing factors were investigated.

Chen, Zhanguang; Zhu, Li; Song, Tianhe; Chen, Junhui; Guo, Zhiming

2009-04-01

222

The coplanar resonator technique for determining the surface impedance of YBa2Cu3O7-? thin films  

Microsoft Academic Search

We describe how coplanar microwave resonators fabricated from patterned thin films of YBa2Cu3O7(-?) (YBCO) can he used to measure the ab-plane microwave surface impedance Zs=Rs+jXs of the films, in particular the absolute value and temperature dependence of the magnetic penetration depth ?. The current distribution of the resonator is calculated by modelling the resonator as a network of coupled transmission

A. Porch; M. J. Lancaster; R. G. Humphreys

1995-01-01

223

Dynamic orientational disorder of the nitro group in 2-chloro-nitrobenzene revealed through 35 Cl nuclear quadrupole resonance  

NASA Astrophysics Data System (ADS)

In the present paper we analyse the contributions of nitro group movements in 2-chloro-nitrobenzene to the nuclear quadrupole resonance (NQR) parameters of the chlorine nucleus in the molecule. We found two contributions to the spin-lattice relaxation time (T1) and the NQR frequency (?Q) due to the onset of nitro group movements in the molecule. One of these contributions is the well-known semirotation of the nitro group around the N-C axis. The other one is attributed to some tilting or tipping of the nitro plane away from the benzene ring introducing some dynamic orientational disorder of this group in the crystal only observed as a contribution from the temperature dependence of T1 and ?Q. Its activation energy is similar to that of the nitro group reorientation (21.9 and 23.6 kJ mol-1 for the two processes) and may arise from competing crystalline and steric chlorine nucleus effects. The present investigation shows that in chloronitrobenzenes the NO2 group dynamic orientational disorder can produce modulation effects on the chlorine T1 which are large enough to be observed by means of the NQR.

Brunetti, Aldo H.

2002-09-01

224

Resonant behavior of dielectric objects (electrostatic resonances).  

PubMed

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

Fredkin, D R; Mayergoyz, I D

2003-12-19

225

Study of the interaction of nucleic acids with acridine red and CTMAB by a resonance light scattering technique and determination of nucleic acids at nanogram levels  

Microsoft Academic Search

In this paper, a determinating method of nucleic acids at nanogram levels by a resonance light scattering (RLS) technique with a common spectrofluorometer has been reported. The characteristics of RLS spectra of acridine red (AR) with nucleic acids, the effective factors and the optimum conditions have been studied. In the pH range 6.407.10, nucleic acids and surfactant CTMAB can jointly

Min Wang; Jinghe Yang; Xia Wu; Fang Huang

2000-01-01

226

A 35-60 GHz single-pole double-throw(SPDT) switching circuit using direct contact MEMS switches and double resonance technique  

Microsoft Academic Search

In this paper, a single-pole double-throw(SPDT) switching circuit was demonstrated using direct contact MEMS switches and double resonance technique for Q-band and V-band applications. The size of the fabricated SPDT switching circuit is about 1 mm2 mm. The direct contact MEMS switches are formed on the CPW transmission lines and actuated with electrostatic force. The fabricated single-pole single-throw(SPST) MEMS switch

Jae-Hyoung Park; Sanghyo Lee; Jug-Mu Kim; Youngwoo Kwon; Yong-Kweon Kim

2003-01-01

227

Nitroxide-controlled free radical copolymerization of styrene and acrylonitrile monitored by electron spin resonance and fourier transform infrared technique in situ  

Microsoft Academic Search

Nitroxide-mediated homopolymerization of styrene (St) and copolymerization of styrene and acrylonitrile (An) were monitored\\u000a respectively by electron spin resonance and Fourier transform infrared technique in situ, and the polymerization kinetics\\u000a was investigated in detail. Homopolymerization of St was well controlled in the presence of 4-hydroxyl-2,2,6,6-tetramethyl-l-piperidinyloxy\\u000a (HTEMPO, N*) at high temperature. The initiation reactions and polymerization rates were changed by varying

F. J. Hua; S. M. Chen; D. S. Lee; Y. L. Yang

2001-01-01

228

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

229

A versatile computer-controlled pulsed nuclear quadrupole resonance spectrometer  

NASA Astrophysics Data System (ADS)

A new, pulsed nuclear quadrupole resonance (NQR) spectrometer capable of performing a variety of pulsed and swept experiments is described. The spectrometer features phase locked, superheterodyne detection using a commercial spectrum analyzer and a fully automatic, computer-controlled tuning and matching network. The tuning and matching network employs stepper motors which turn high power air gap capacitors in a ``moving grid'' optimization strategy to minimize the reflected power from a directional coupler. In the duplexer circuit, digitally controlled relays are used to switch different lengths of coax cable appropriate for the different radio frequencies. A home-built pulse programmer card controls the timing of radio frequency pulses sent to the probe, while data acquisition and control software is written in Microsoft Quick Basic. Spin-echo acquisition experiments are typically used to acquire the data, although a variety of pulse sequences can be employed. Scan times range from one to several hours depending upon the step resolution and the spectral range required for each experiment. Pure NQR spectra of NaNO2 and 3-aminopyridine are discussed.

Fisher, Gregory; Macnamara, Ernesto; Santini, Robert E.; Raftery, Daniel

1999-12-01

230

139La nuclear magnetic resonance characterisation of La2O3 and La1-xSrxMO3 where M = Cr, Mn or Co.  

PubMed

139La Nuclear magnetic resonance (NMR) spectra have been used to obtain nuclear quadrupole coupling parameters for La2O3 and a series of perovskites La1-xSrxMO3 (where M = Cr, Mn or Co). Depending on the doping level of SrO2 these materials are either paramagnetic or ferromagnetic at room temperature. Magnetic transferred hyperfine effects are strongly in evidence in the Mn compounds. A 59Co NMR spectrum was observed in LaCoO3. A precision measurement of the nuclear quadrupole coupling constant in La2O3 was made by nuclear quadrupole resonance (NQR) spectroscopy. PMID:7827974

Bastow, T J

1994-02-01

231

Simulations of imaging of the local density of states by a charged probe technique for resonant cavities  

NASA Astrophysics Data System (ADS)

We simulate scanning probe imaging of the local density of states related to scattering Fermi level wave functions inside a resonant cavity. We calculate the potential landscape within the cavity, taking into account the Coulomb charge of the probe and its screening by deformation of the two-dimensional electron gas using the local density approximation. Approximation of the tip potential by a Lorentz function is discussed. The electron transfer problem is solved with a finite difference approach. We look for stable work points for the extraction of the local density of states from conductance maps. We find that conductance maps are highly correlated with the local density of states when the Fermi energy level enters into Fano resonance with states localized within the cavity. Generally outside resonances the correlation between the local density of states and conductance maps is low.

Kolasi?ski, K.; Szafran, B.

2013-10-01

232

Measurement of the 183 keV Resonance in 17O(p,alpha)14N using a Novel Technique  

SciTech Connect

We have developed a novel technique for measurements of low energy (p,alpha) reactions using heavy ion beams and a differentially-pumped windowless gas target. We applied this new approach to study the 183 keV resonance in the 17O(p,alpha)14}N reaction. We report a resonance energy (center-of-mass) of 183.5{+0.1}{-0.4} keV, a resonance strength of 1.70 +/- 0.15 meV, and set an upper limit (95\\% confidence) on the total width of the state of < 0.1 keV. This resonance is important for the 17O(p,alpha)14}N reaction rate, and we find that 18F production is significantly decreased in low mass ONeMg novae but less affected in more energetic novae. We also report the first determination of the stopping power for oxygen ions in hydrogen gas near the peak of the Bragg curve (E=193 keV/u) to be (63+/-1)e-15 eV-cm2.

Moazen, Brian H [ORNL; Bardayan, Daniel W [ORNL; Blackmon, Jeff C [ORNL; Chae, Kyung Yuk [ORNL; Chipps, Kelly A [ORNL; Domizioli, Carlo P [ORNL; Fitzgerald, Ryan [ORNL; Greife, Uwe [ORNL; Hix, William Raphael [ORNL; Grzywacz-Jones, Kate L [ORNL; KOZUB, RAYMOND L [ORNL; Lingerfelt, Eric J [ORNL; Livesay, Jake [ORNL; Nesaraja, Caroline D [ORNL; Pain, Steven D [ORNL; Roberts, Luke F [ORNL; Shriner, Jr., John F [ORNL; Smith, Michael Scott [ORNL; Thomas, Jeffrey S [ORNL

2007-01-01

233

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

234

s-wave superconductivity in superconducting BaTi2Sb2O revealed by 121/123Sb-NMR/nuclear quadrupole resonance measurements  

NASA Astrophysics Data System (ADS)

We report the 121/123Sb-NMR/nuclear quadrupole resonance (NQR) measurements on the superconductor BaTi2Sb2O with a two-dimensional Ti2O square-net layer formed with Ti3+ (3d1). NQR measurements revealed that the in-plane four-fold symmetry is broken at the Sb site below TA40 K, without an internal field appearing at the Sb site. These exclude a spin-density wave (SDW)/ charge density wave (CDW) ordering with incommensurate correlations, but can be understood with the commensurate CDW ordering at TA. The spin-lattice relaxation rate 1/T1, measured at the four-fold symmetry breaking site, decreases below superconducting (SC) transition temperature Tc, indicative of the microscopic coexistence of superconductivity and the CDW/SDW phase below TA. Furthermore, 1/T1 of 121Sb-NQR shows a coherence peak just below Tc and decreases exponentially at low temperatures. These results are in sharp contrast with those in cuprate and iron-based superconductors, and strongly suggest that its SC symmetry is classified to an ordinary s-wave state.

Kitagawa, S.; Ishida, K.; Nakano, K.; Yajima, T.; Kageyama, H.

2013-02-01

235

Isotope effect on the temperature dependence of the 35Cl NQR frequency in (NH4)2RuCl6  

NASA Astrophysics Data System (ADS)

35Cl NQR of (NH4)2RuCl6, (ND4)2RuCl6, (NH4)2SnCl6, and (ND4)2SnCl6 was measured.Isotope effect on the spatial distribution of hydrogen atoms is discussed.Tunneling splittings of torsional ground state of ammonium ions were estimated.Origin of T1Q anomaly previously reported in (NH4)2SnCl6 and (ND4)2SnCl6 was revealed.

Kume, Yoshio; Amino, Daiki; Asaji, Tetsuo

2013-07-01

236

/sup 79/ /sup 81/Br NQR spectra of bromochalcogenide complexes of Au(III), Pt(IV), and Pd(II)  

SciTech Connect

The structure of bromochalcogenide complexes of gold, platinum, and palladium, viz., AuBr/sub 4/ x SeBr/sub 3/, PtBr/sub 6/(SeBr/sub 3/)/sub 2/, PtBr/sub 6/(TeBr/sub 3/)/sub 2/, and PdBr/sub 2/(SeBr/sub 2/)/sub 2/, has been established with the aid of the NQR spectra of the bromine atoms. In the compounds of gold and platinum investigated SeBr/sub 3/ groupings are coordinated as ligands, and in the palladium complex SeBr/sub 2/ groupings serve as ligands.

Fokina, Z.A.; Kuznetsov, S.I.; Timoshchenko, N.I.; Bryukhova, E.V.

1987-01-10

237

NMR and NQR study of the electronic and structural properties of Al-Cu-Fe and Al-Cu-Ru quasicrystals  

SciTech Connect

[sup 27]Al and [sup 63,65]Cu NMR is reported for powdered stable Al-Cu-Fe and Al-Cu-Ru icosahedral quasicrystals and crystalline approximants, and for an Al-Pd-Mn single-grain quasicrystal. [sup 27]Al NQR spectra at 4.2 K were observed in Al-Cu-Fe and Al-Cu-Ru samples. From quadrupole-perturbed NMR spectra at different magnetic fields, and from zero-field NQR spectra, a wide distribution of local electric-field gradient (EFG) tensor components and principal-axis-system orientations was found at the Al site. A model EFG calculation based on a 1/1 Al-Cu-Fe approximant successfully explained the observed NQR spectra. The average local gradient is largely determined by the [ital p]-electron wave function at the Al site, while the width of the distribution is due to EFG lattice contribution. Comparison of [sup 63]Cu and [sup 27]Al NMR shows the EFG distribution at the two sites is similar, but the electronic contribution to the EFG is considerably smaller at the Cu site, in agreement with a more [ital s]-type wave function of the conduction electrons. Overall spread of EFG values is well reproduced by calculation based on the approximant. However, the experimental spectra indicate a much larger number of nonequivalent sites when compared with the simulated NQR spectra based on the 1/1 approximant. The short-range, local chemical order is well represented by the approximant, but differences in coordination must be included at intermediate range in the quasicrystal. Measured [sup 27]Al Knight shift, magnetic susceptibility, and nuclear spin-lattice relaxation time as a function of temperature indicate reduced density of states at the Fermi level by a factor of 7 or 8 from the value in Al metal, consistent with the notion of a pseudogap for these quasicrystals. No differences in measured parameters were detected as a function of composition of the quasicrystalline alloys.

Shastri, A.; Borsa, F.; Torgeson, D.R.; Shield, J.E.; Goldman, A.I. (Ames Laboratory, U.S. Department of Energy and Department of Physics Astronomy, Iowa State University, Ames, Iowa 50011 (United States))

1994-12-01

238

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

Microsoft Academic Search

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

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

1981-01-01

239

Tumor perfusion studies using fast magnetic resonance imaging technique in advanced cervical cancer: A new noninvasive predictive assay  

Microsoft Academic Search

Purpose: This study investigated sequential changes in tumor blood supply using magnetic resonance (MR) perfusion imaging and assessed their significance in the prediction of outcome of patients with advanced cervical cancer. The purpose of this project was to devise a simple, noninvasive method to predict early signs of treatment failure in advanced cervical cancer treated with conventional radiation therapy.Methods and

Nina A. Mayr; William T. C. Yuh; Vincent A. Magnotta; James C. Ehrhardt; James A. Wheeler; Joel I. Sorosky; Charles S. Davis; B.-Chen Wen; Douglas D. Martin; Retta E. Pelsang; Richard E. Buller; Larry W. Oberley; David E. Mellenberg; David H. Hussey

1996-01-01

240

RADIATION DAMAGE STUDIES IN SOLIDS NUCLEAR RESONANCE ABSORPTION TECHNIQUE. Period covered: January 1, 1958 through October 31, 1958  

Microsoft Academic Search

Nuclear magnetic resonance (NMR) studies of neutron-irradiated LiF ; crystals have resulted in the detection of colloidal lithium metal and molecular ; fluorine gas. Quantitative determinations of the amount of damage and the ; behavior of the displaced metal and halide ions appear to be possible. The ; defect density in neutron-irradiated KBr has been checked as a function of

Bray

1958-01-01

241

In vivo electron spin resonance-computed tomography\\/nitroxyl probe technique for non-invasive analysis of oxidative injuries  

Microsoft Academic Search

Free radicals are widely recognized as harmful chemical species in oxidative tissue injury. However, there have been no satisfying methods to visualize free radicals in vivo non-invasively with information of their localization and amount. In vivo electron spin resonance (ESR) spectroscopy was recently developed to measure free radicals generated in rodents. Several kinds of stable nitroxyl radicals were used as

Hideo Utsumi; Ken-ichi Yamada

2003-01-01

242

High-resolution wave number spectrum using multi-point measurements in space - the Multi-point Signal Resonator (MSR) technique  

NASA Astrophysics Data System (ADS)

A new analysis method is presented that provides a high-resolution power spectrum in a broad wave number domain based on multi-point measurements. The analysis technique is referred to as the Multi-point Signal Resonator (MSR) and it benefits from Capon's minimum variance method for obtaining the proper power spectral density of the signal as well as the MUSIC algorithm (Multiple Signal Classification) for considerably reducing the noise part in the spectrum. The mathematical foundation of the analysis method is presented and it is applied to synthetic data as well as Cluster observations of the interplanetary magnetic field. Using the MSR technique for Cluster data we find a wave in the solar wind propagating parallel to the mean magnetic field with relatively small amplitude, which is not identified by the Capon spectrum. The Cluster data analysis shows the potential of the MSR technique for studying waves and turbulence using multi-point measurements.

Narita, Y.; Glassmeier, K.-H.; Motschmann, U.

2011-02-01

243

A highly sensitive assay for protein using resonance light-scattering technique with dibromohydroxyphenylfluoronemolybdenum(VI) complex  

Microsoft Academic Search

At pH 2.8 and in the presence of 0.090% p-octylpolyethyleneglycol phenylether, the resonance light-scattering (RLS) spectrum of molybdenum(VI) complex with dibromohydroxyphenylfluorone (DBHPF) has a sharp peak at 586 nm. If the micro protein coexists with Mo(VI) and DBHPF, the RLS intensity of the complex at 586 nm is significantly enhanced by protein due to the binding interaction between protein and

Zhong-Xian Guo; Han-Xi Shen

1999-01-01

244

Off-chip 400 Mbps signal transmission: noise reduction using non-resonant lengths and other techniques  

Microsoft Academic Search

A 400 Mbps single-ended off-chip link including an open-drain driver and quasi-differential receiver has been designed, simulated, and measured. In this work, the design choices, in particular as related to noise tolerance, are discussed. To reduce the reflections inherent in signal propagation at a 400 Mbps rate, both the data and clock interconnects are restricted to non-resonant lengths. To further

H. Blennemann; Yao-Chao Yang; R. Nikel

1996-01-01

245

Determination of nucleic acids at nanogram levels with safranine T by a resonance light-scattering technique  

Microsoft Academic Search

This is the first report of the determination of nucleic acids based on their template roles for long range assembly of organic dyes. At pH 7.05 and ionic strength 0.0045, the interactions of safranine T (ST) with nucleic acids result in three characteristic peaks of resonance light scattering (RLS) at 328.0, 472.0 and 572.0nm. Mechanistic studies show that these peaks

Cheng Zhi Huang; Yuan Fang Li; Xi Dong Liu

1998-01-01

246

DETERMINATION OF TOTAL PROTEIN CONTENT IN HUMAN SERUM SAMPLES WITH FAST RED VR BY RESONANCE LIGHT SCATTERING TECHNIQUE  

Microsoft Academic Search

In an acidic medium, the interaction of Fast red VR (FRV) with proteins such as bovine serum albumin (BSA), human serum albumin (HSA), pepsin (Pep), ?-chymotrypsin (Chy), and lysozyme (Lys) was characterized by measuring enhanced resonance light-scattering (RLS) signals. It was found that the enhanced RLS intensities of FRV by proteins at 287.0nm were in proportion to the concentrations of

Chuan Xiao Yang; Yuan Fang Li; Cheng Zhi Huang

2002-01-01

247

?-irradiated [(CH 3) 4N] 2SiF 6 single crystal investigation by electron paramagnetic resonance technique  

Microsoft Academic Search

In this study, ?-irradiation damage centers in [(CH3)4N]2SiF6 single crystal has been investigated by electron paramagnetic resonance spectroscopy (EPR) at room temperature. It has been found that ?-irradiation produces the (CH3)3N+ radicals in this compound. The g factor and the hyperfine constant for H atoms, measured as 28.7G, were found to be isotropic. The hyperfine coupling constant of the N

E. Bozkurt; I. Kartal; B. Karabulut

2007-01-01

248

35Cl quadrupole resonance study of the thermally activated motion of the nitro group in chlorinated nitrobenzenes  

NASA Astrophysics Data System (ADS)

The results of NQR studies of the thermoactivated motion of NO2 groups in chlorine-containing nitrobenzenes are presented. A procedure for analyzing the experimental data is suggested. It uses the characteristic temperature of the minimum of the modulation contribution to the temperature dependence of the spin-lattice relaxation time T 1 of the resonant probe nuclei (35Cl) bonded with the moving group by nonvalent interactions. The activation energy of the thermoactivated motion was correlated with the temperature of the minimum. The possibility of a temperature dependence of the activation energy of the NO2 group was examined.

Kyuntsel, I. A.

2013-05-01

249

Conceptual Study on New Isotope Analysis Technique with Resonance Ionization Mass Spectrometry Using Inductively Coupled Plasma as an Atomic Source (ICP-RIMS)  

SciTech Connect

We have proposed the novel isotope analysis technique with Resonance Ionization Mass Spectrometry using Inductively Coupled Plasma as an atomic source (ICP-RIMS). Each component of ICP-RIMS is conceptually designed. We conclude that the orthogonal acceleration time-of-flight mass spectrometer (oa-TOF-MS) driven by a high-repetition-rate pulsed laser would be suitable system for ICP-RIMS. We, additionally, suggest that the first vacuum stage of the vacuum interface, which is between the sampling and skimmer cones, is desired to maintain as low pressure as possible in order to suppress the Doppler broadening and to skim the supersonic jet effectively.

Watanabe, K.; Uritani, A. [Department of Materials, Physics and Energy Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603 (Japan); Higuchi, Y.; Tomita, H.; Kawarabayashi, J.; Iguchi, T. [Department of Quantum Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603 (Japan)

2009-03-17

250

NQR, NMR and Crystal Structure Studies of [C(NH2)3]2HgX4 (X = Br, I)  

NASA Astrophysics Data System (ADS)

The crystal structure of [C(NH2)3]2HgBr4 has been determined at room temperature: monoclinic, space group C2/c, with a = 10.035(2), b = 11.164(2), c = 13.358(3) , ? = 111.67(3), and Z = 4. The crystal consists of planar [C(NH2)3]+ and distorted tetrahedral [HgBr4]2- ions. The Hg atom is located on a two-fold axis such that two sets of inequivalent Br atoms exist in an [HgBr4]2- ion. In accordance with the crystal structure, two 81Br NQR lines widely separated in frequency were observed between 77 and ca. 380 K. [C(NH2)3]2HgI4 yielded four 127I NQR lines ascribable to m = 1/2 ? 3/2 transitions, indicating that its crystal structure is different from the bromide complex. The 1H NMR T 1 measurements showed a single minimum for the bromide but two minima for the iodide. The analyses based on the C3 reorientations of the planar [C(NH2)3]+ ions gave the activation energies of 29.8 kJ mol-1 for the bromide, and 30.2 and 40.0 kJ mol-1 for the iodide.

Furukawa, Y.; Terao, H.; Ishihara, H.; Gesing, T. M.; Buhl, J.-C.

2004-12-01

251

NMR and NQR study of Si-doped (6,0) zigzag single-walled aluminum nitride nanotube as n or P-semiconductors.  

PubMed

Density functional theory (DFT) calculations were performed to investigate the electronic structure properties of pristine and Si-doped aluminum nitride nanotubes as n or P-semiconductors at the B3LYP/6-31G* level of theory in order to evaluate the influence of Si-doped in the (6,0) zigzag AlNNTs. We extended the DFT calculation to predict the electronic structure properties of Si-doped aluminum nitride nanotubes, which are very important for production of solid-state devices and other applications. To this aim, pristine and Si-doped AlNNT structures in two models (Si(N) and Si(Al)) were optimized, and then the electronic properties, the isotropic (CS(I)) and anisotropic (CS(A)) chemical shielding parameters for the sites of various (27)Al and (14)N atoms, NQR parameters for the sites of various of (27)Al and (14)N atoms, and quantum molecular descriptors were calculated in the optimized structures. The optimized structures, the electronic properties, NMR and NQR parameters, and quantum molecular descriptors for the Si(N) and Si(Al) models show that the Si(N) model is a more reactive material than the pristine or Si(Al) model. PMID:22588584

Baei, Mohammad T; Peyghan, Ali Ahmadi; Tavakoli, Khadijeh; Babaheydari, Ali Kazemi; Moghimi, Masoumeh

2012-05-16

252

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

253

Evaluation of [sup 31]P magnetic resonance spectroscopy localization techniques in human myocardium and soft-tissue sarcomas  

SciTech Connect

The overall goals of this thesis are to establish and evaluate [sup 31]P MR spectroscopy localization techniques for their application to the study of human myocardium and sarcomas. Several localization techniques which include 1D-CSI, ISIS, ISIS/CSI, and 2D-CSI were evaluated in the myocardial muscle of normal subjects and patients receiving 5-fluorouracil (5-FU) chemotherapy. Among these localization techniques, 2D-CSI is recommended since it shows good selectivity, good flexibility and a good compromise between sensitivity patient toleration limits. These localization techniques were also evaluated in patients with osteosarcoma and soft-tissue sarcomas. Among these localization techniques, 1D-CSI is recommended for big and superficial tumors. Further definition of the voxel is provided by using 2D-CSI or 3D-CSI in the case of small or deep seated tumors. Several techniques that should improve the [sup 31]P MR spectroscopic study of patients in the future are evaluated on the phantom. These include the presaturation of the chest wall muscle for improved myocardial spectral using the CSI sequence, implementation of the BIR-4 pulse for variable angle adjustable pulse, and the proton decoupling technique for improved resolution and sensitivity. The good performance of the phantoms studies show that these techniques can be further extended to the normal subject and patient studies.

Li, Chun-Wei.

1993-01-01

254

The neuronal nitric oxide synthase inhibitor, TRIM, as a neuroprotective agent: effects in models of cerebral ischaemia using histological and magnetic resonance imaging techniques.  

PubMed

Most neuroprotective compounds that appear promising in the pre-clinical phase of testing are subsequently dismissed as relatively ineffective when entered into large-scale clinical trials. Many pre-clinical studies of potential neuroprotective candidates evaluate efficacy in only one or possibly two different models of ischaemia. In this study we examined the effects of 1,2-trifluoromethylphenyl imidazole (TRIM), a novel neuronal nitric oxide synthase (nNOS) inhibitor, in three models of cerebral ischaemia (global gerbil, global rat and focal rat). In addition, to follow the progression of the pathology, we also compared traditional histology methods with more advanced magnetic resonance imaging (MRI) as endpoint measures for neurological damage and neuroprotection. TRIM (50 mg/kg i.p.) prevented ischaemia-induced hippocampal damage following global ischaemia in gerbils when administered before or immediately post-occlusion, but failed to protect when administration was delayed until 30 min post-occlusion. Further studies indicated that the compound (administered at 50 mg/kg, i.p., immediately after occlusion) also protected in a rat four-vessel occlusion (4-VO) model using both histological and diffusion-weighted (DW) imaging techniques. In a final study, TRIM (50 mg/kg i.p. 30 min after occlusion) provided a significant reduction in infarct volume at 4 and 24 h as measured using diffusion-weighted (DW) and proton density (PD)-weighted magnetic resonance imaging (MRI). This was confirmed using histological techniques. These studies confirm that nNOS inhibitors may have utility in stroke and provide evidence that combined magnetic resonance and histological methods can provide a powerful method of assessing neuronal damage in rodent models of cerebral ischaemia. PMID:14642829

Haga, Kristin K; Gregory, Lloyd J; Hicks, Caroline A; Ward, Mark A; Beech, John S; Bath, Phillip W; Williams, Steven C R; O'Neill, Michael J

2003-12-12

255

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

Microsoft Academic Search

139La nuclear quadrupole resistance (NQR) and relaxation measurements in lightly hole-doped La1.8-xEu0.2SrxCuO4 have been used to investigate the microscopic properties of the low-temperature orthorhombic to low-temperature tetragonal transition. The transition is characterized by a sharp peak in 139La NQR relaxation rate, indicating phonon softening. We find that the structural phase transition is accompanied by a modification of the spin state.

B. J. Suh; P. C. Hammel; M. Hcker; B. Bchner

1999-01-01

256

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

SciTech Connect

Our previous studies (1,2) on the zerofield NMR spectra of Cu/Co catalysts revealed that the method of preparation sensitively influences the magnetic character of the Catalyst. Catalytic studies of the earlier investigators also (3) show similar influence on the product selectivity and indicate reproducible performance is critically dependent on the control and rigor of the preparation technique. To compliment the NMR results, we have made a thorough investigation of the Hysteresis character of the Cu/Co catalysts with the metal ratio varying from 0.2 to 4.0.

Not Available

1991-12-17

257

A highly sensitive assay for protein using resonance light-scattering technique with dibromohydroxyphenylfluorone-molybdenum(VI) complex.  

PubMed

At pH 2.8 and in the presence of 0.090% p-octylpolyethyleneglycol phenylether, the resonance light-scattering (RLS) spectrum of molybdenum(VI) complex with dibromohydroxyphenylfluorone (DBHPF) has a sharp peak at 586 nm. If the micro protein coexists with Mo(VI) and DBHPF, the RLS intensity of the complex at 586 nm is significantly enhanced by protein due to the binding interaction between protein and DBHPF-Mo(VI) complex. Based on this a new assay for protein is described. The dynamic ranges for bovine and human serum albumins are both 0.05-0.75 mg l-1 with detection limits of 13 and 15 ng ml-1, respectively. Besides high sensitivity, the method is characterized by good reproducibility, rapidity of reaction, good stability of chemical system, commonality of spectrofluorometer, few coexisting substances, especially detergents. The determinations of diluted human serum and urine by this method give the results very close to these by the Coomassie brilliant blue G-250 colorimetry, with relative standard deviations of five duplicates of 1.8-2.5%. PMID:10659451

Guo, Z X; Shen, H X

1999-12-01

258

Hybrid proton resonance frequency/T1 technique for simultaneous temperature monitoring in adipose and aqueous tissues.  

PubMed

Thermal therapy procedures being carried out under MR guidance would be safer if temperature changes could be accurately monitored in both water-based and fat-based tissues. To this end, we present a hybrid proton resonance frequency (PRF)/T(1) approach for simultaneously measuring PRF shift temperatures in water-based tissues and T(1) changes in fat-based tissues. The hybrid PRF/T(1) sequence is a standard radiofrequency spoiled gradient echo sequence executed in a dynamic mode with two flip angles alternating every time frame. The PRF information is extracted every time frame using the image phase in the standard approach, and the T(1) information is extracted every two time frames using a variable flip angle approach. Simulation studies, ex vivo high intensity focused ultrasound heating experiments, and in vivo stability experiments were performed to test the feasibility of the approach. The results indicate that the hybrid PRF/T(1) approach provides PRF temperature maps of the same quality as those obtained by traditional PRF methods while simultaneously being able to track T(1) changes in fat-based tissues. Although several potential error sources exist for the T(1) measurements, the approach is a promising start toward realizing quantitative temperature measurements in both water-based and fat-based tissues. PMID:22392856

Todd, Nick; Diakite, Mahamadou; Payne, Allison; Parker, Dennis L

2012-03-05

259

Determination of dopamine at the nanogram level based on the formation of Prussian blue nanoparticles by resonance Rayleigh scattering technique  

NASA Astrophysics Data System (ADS)

In pH 2.6 HCl solution, dopamine (DA) could reduce Fe(III) to Fe(II), which further reacted with [Fe(CN) 6] 3- to form a Fe 3[Fe(CN) 6] 2 complex. By virtue of hydrophobic force and Van der Waals force, the complex aggregated to form Fe 3[Fe(CN) 6] 2 nanoparticles with the average diameter of about 20 nm. This resulted in a significant enhancement of resonance Rayleigh scattering (RRS). The maximum wavelength of the ion-association complex was located at about 350 nm. The increment of scattering intensity (? IRRS) was directly proportional to the concentration of DA in the range of 0.06-1.0 ?g/mL. This method has high sensitivity and the detection limit (3 ?) for DA was 3.43 ng/mL. In this work, the characteristics of absorption and RRS spectra of this reaction have been studied. The optimum reaction condition and influencing factors have been investigated. The method was applied to the determination of DA in pharmaceutical samples with satisfactory results. Furthermore, the reaction mechanism and the reasons of RRS enhancement have been explored.

Dong, Jiang Xue; Wen, Wei; Li, Nian Bing; Luo, Hong Qun

2012-02-01

260

An analytical technique for the synthesis of cascaded N-tuplets cross-coupled resonators microwave filters using matrix rotations  

Microsoft Academic Search

In this paper, a general simple technique for reducing any canonical n+2 coupling matrix to the more useful modular (i.e., cascaded N-tuplets) form is presented. This is accomplished by performing a suitable sequence of matrix rotations whose angles are not derived through optimization, but are analytically computed from the starting coupling matrix elements and the transmission zeros frequencies. The proposed

Stefano Tamiazzo; Giuseppe Macchiarella

2005-01-01

261

A novel technique for the pre-concentration and extraction of inositol hexakisphosphate from soil extracts with determination by phosphorus-31 nuclear magnetic resonance.  

PubMed

Inositol hexakisphosphate (IP6) is often the dominant form of soil organic phosphorus (P), but is rarely investigated because of the analytical difficulties encountered in its extraction, separation, and detection in environmental samples. In particular, recent advances in the study of soil organic P with 31P nuclear magnetic resonance (NMR) have been of limited use for the study of IP6, because the technique does not discriminate between IP6 and other forms of P. This was addressed by developing a novel analytical procedure using the retentive properties of gel-filtration gels for IP6, which allows the combined selective extraction and pre-concentration of IP6 from soil extracts with determination by 31P NMR. While the technique is still in the developmental stage, the results demonstrate that the gel does not interfere with 31P NMR analysis and retains IP6 to concentrations well above those required to give clear spectral signals. The technique has considerable potential for application to the study of IP6 in soil extracts and water samples and, with development, could help to answer fundamental questions regarding the dynamics of organic P in the environment. PMID:11931435

Turner, Benjamin L; McKelvie, Ian D

262

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

263

Detection of Antiferromagnetic Ordering in Heavily Doped LaFeAsO1-xHx Pnictide Superconductors Using Nuclear-Magnetic-Resonance Techniques  

NASA Astrophysics Data System (ADS)

We studied double superconducting (SC) domes in LaFeAsO1-xHx by using As75 and H1 nuclear-magnetic-resonance techniques and unexpectedly discovered that a new antiferromagnetic (AF) phase follows the double SC domes on further H doping, forming a symmetric alignment of AF and SC phases in the electronic phase diagram. We demonstrated that the new AF ordering originates from the nesting between electron pockets, unlike the nesting between electron and hole pockets, as seen in the majority of undoped pnictides. The new AF ordering is derived from the features common to high-Tc pnictides; however, it has not been reported so far for other high-Tc pnictides because of their poor electron doping capability.

Fujiwara, N.; Tsutsumi, S.; Iimura, S.; Matsuishi, S.; Hosono, H.; Yamakawa, Y.; Kontani, H.

2013-08-01

264

A novel intubation technique for minimally invasive longitudinal studies of rat lungs using hyperpolarized 3He magnetic resonance imaging.  

PubMed

Hyperpolarized noble gas (HNG) magnetic resonance imaging (MRI) has been shown to be useful for studying rodent models of lung disease. Image quality can be substantially degraded by signal loss from molecular oxygen entering the airway, requiring invasive surgery to ensure a good seal between the endotracheal (ET) tube and trachea. A modified Foley catheter having an inflatable cuff near the tip provides a novel approach for ensuring image quality for HNG MRI, thereby enabling longitudinal studies and reducing animal numbers. A Foley catheter was modified for rodent intubation and to minimize dead space. Three pairs of age-matched male Sprague Dawley rats 400 (30) g were used. Two pairs were intubated using the Foley and the third with an intravenous catheter. Leak rates were measured from pressure versus time curves within each animal. The pairs were euthanized immediately or six days postrecovery to assess the effects of the procedure on animal health, as reflected by histological examination. The Foley catheter resulted in minimal leak rates (-0.20 (0.03) versus -0.16 (0.05) cmH(2)O/s), and were shown to be well below upper-limit leak rates of -0.5 and -0.7 cmH(2)O/s. Tracheal samples from rats in a separate Foley group (not mechanically ventilated) showed superficial damage six days postextubation (grade = 0). (3)He imaging performed using the Foley showed good image quality. Though some technical issues remain to be solved, a modified Foley catheter used as an ET tube offers the potential to enable longitudinal studies in rodents and reduce animal numbers. PMID:23097565

Fox, M S; Welch, I; Hobson, D; Santyr, G E

2012-10-01

265

^63Cu NMR and NQR study of the stripe phase in La_1.6-xNd_0.40Sr_xCuO_4  

NASA Astrophysics Data System (ADS)

We find that the integrated intensity of ^63Cu NQR in La_1.6-xNd_0.40Sr_xCuO4 decreases dramatically below the stripe ordering temperature.(P.M. Singer et al.),Phys. Rev. B 60, 15345 (1999).(A.W. Hunt et al.),Phys. Rev. Lett. 82, 4300 (1999). Comparison with scattering results indicates that the missing signal represents the stripe order parameter. We observe that the loss of signal is sharpest for x ~1/8, indicating that x ~1/8 is the optimal concentration for stripe formation. This work was supported by the National Science Foundation (DMR 99-71266, DMR 98-08941), the A.P. Sloan Foundation, the Mitsui Foundation, and the Platzman Fund.

Singer, Philip M.; Hunt, Allen W.; Cederstrm, Agneta F.; Imai, Takashi

2000-03-01

266

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

267

14N nuclear quadrupole resonance of picolinic, nicotinic, isonicotinic and dinicotinic acids  

NASA Astrophysics Data System (ADS)

The 14N nuclear quadrupole resonance (NQR) quadrupole coupling tensors of picolinic, nicotinic, isonicotinic and dinicotinic acids have been determined. Two different 14N quadrupole coupling constants 1007 kHz and 4159 kHz have been observed for picolinic acid demonstrating the presence of both protonated and non-protonated nitrogen atoms in this system in the solid. Only one set of non-protonated 14N NQR lines has been observed in other pyridinecarboxylic acids demonstrating the absence of the protonated zwitter ion forms observed in picolinic acid. The non-protonated 14N quadrupole coupling constant is the highest for the non-protonated nitrogen in picolinic acid and decreases to 3774 kHz in nicotinic acid and 3570 kHz in isonicotinic acid. It is the lowest in dinicotinic acid where the corresponding 14N quadrupole coupling constant is 2794 kHz. The observed anomalous decrease in the 14N quadrupole coupling constant of dinicotinic acid with decreasing temperature is tentatively explained as reflecting the increase in the residence time of the N-H⋯O bonded proton in the potential well close to the nitrogen.

Seliger, J.; agar, V.; Zidanek, A.; Blinc, R.

2006-12-01

268

Charge order and low frequency spin dynamics in lanthanum cuprates revealed by Nuclear Magnetic Resonance  

NASA Astrophysics Data System (ADS)

We report detailed 17O, 139La, and 63,65Cu Nuclear Magnetic Resonance (NMR) and Nuclear Quadrupole Resonance (NQR) measurements in a stripe ordered La1.875Ba0.125CuO4 single crystal and in oriented powder samples of La1.8- x Eu0.2Sr x CuO4. We observe a partial wipeout of the 17O NMR intensity and a simultaneous drop of the 17O electric field gradient (EFG) at low temperatures where the spin stripe order sets in. In contrast, the 63,65Cu intensity is completely wiped out at the same temperature. The drop of the 17O quadrupole frequency is compatible with a charge stripe order. The 17O spin lattice relaxation rate shows a peak similar to that of the 139La, which is of magnetic origin. This peak is doping dependent and is maximal at x ? 1/8.

Grafe, H.-J.; Curro, N. J.; Young, B. L.; Vyalikh, A.; Vavilova, J.; Gu, G. D.; Hcker, M.; Bchner, B.

2010-10-01

269

Nuclear magnetic resonance with dc SQUID (Super-conducting QUantum Interference Device) preamplifiers  

SciTech Connect

Sensitive radio-frequency (rf) amplifiers based on dc Superconducting QUantum Interface Devices (SQUIDS) are available for frequencies up to 200 MHz. At 4.2 K, the gain and noise temperature of a typical tuned amplifier are 18.6 +- 0.5 dB and 1.7 +- 0.5 K at 93 MHz. These amplifiers are being applied to a series of novel experiments on nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR). The high sensitivity of these amplifiers was demonstrated in the observation of ''nuclear spin noise'', the emission of photons by /sup 35/Cl nuclei in a state of zero polarization. In the more conventional experiments in which one applies a large rf pulse to the spins, a Q-spoiler, consisting of a series array of Josephson junctions, is used to reduce the Q of the input circuit to a very low value during the pulse. The Q-spoiler enables the circuit to recover quickly after the pulse, and has been used in an NQR experiment to achieve a sensitivity of about 2 /times/ 10/sup 16/ nuclear Bohr magnetons in a single free precession signal with a bandwidth of 10 kHz. In a third experiment, a sample containing /sup 35/Cl nuclei was placed in a capacitor and the signal detected electrically using a tuned SQUID amplifier and Q-spoiler. In this way, the electrical polarization induced by the precessing Cl nuclear quadrupole moments was detected: this is the inverse of the Stark effect in NQR. Two experiments involving NMR have been carried out. In the first, the 30 MHz resonance in /sup 119/Sn nuclei is detected with a tuned amplifier and Q-spoiler, and a single pulse resolution of 10/sup 18/ nuclear Bohr magnetons in a bandwidth of 25 kHz has been achieved. For the second, a low frequency NMR system has been developed that uses an untuned input circuit coupled to the SQUID. The resonance in /sup 195/Pt nuclei has been observed at 55 kHz in a field of 60 gauss. 23 refs., 11 figs.

Fan, N.Q.; Heaney, M.B.; Clark, J.; Newitt, D.; Wald, L.; Hahn, E.L.; Bierlecki, A.; Pines, A.

1988-08-01

270

Free-breathing 3D steady-state free precession coronary magnetic resonance angiography: Comparison of four navigator gating techniques  

PubMed Central

This work compares the performance of four navigator gating algorithms (accept/reject (A/R), diminishing variance algorithm (DVA), phase ordering with automatic window selection (PAWS), and retrospective gating (RETRO)) in suppressing respiratory motion artifacts in free-breathing 3D balanced steady-state free precession coronary MRA. In ten volunteers, the right coronary artery (RCA) or the left anterior descending artery (LAD) was imaged (both if time permitted) at 1.5 T with the four gating techniques in random order. Vessel signal, vessel contrast and motion suppression was scored by the consensus of two blinded readers. In 15 imaged vessels (9 RCA and 6 LAD), PAWS provided significantly better image quality than A/R (P < 0.05), DVA (P = 0.02) and RETRO (P = 0.002). While the quality difference between A/R and DVA was not statistically significant, both algorithms yielded significantly better image quality than RETRO. PAWS and DVA were the most efficient algorithms, providing an approximately 20% and 40% relative increase in average navigator efficiency compared to A/R and RETRO, respectively.

Nguyen, Thanh D.; Spincemaille, Pascal; Cham, Matthew D.; Weinsaft, Jonathan W.; Prince, Martin R.; Wang, Yi

2009-01-01

271

A spectroscopic study of the D(0u+) ion-pair state of Br2 by the optical-optical double-resonance technique  

NASA Astrophysics Data System (ADS)

An optical-optical double-resonance technique has been applied to study the D(0u+) ion-pair state of Br2 in a one-photon resonant three-photon absorption. The OODR transition proceeds through the high vibrational level of the B3?(0u+) state, which compromises a large Franck-Condon shift required for the excitation of Br2 from the X1?g+ state to the D(0u+) state. Dunham parameters of the D(0u+) state, based on a global least-squares fit of 407 transitions (v' = 0-16, J' = 17-115), are Y00 = 49928.443(41), Y10 = 134.467(19), Y20 = -8.71(27) 10-2, Y30 = -3.36(10) 10-3, Y01 = 4.2382(15) 10-2, Y11 = -1.061(36) 10-4, Y21 = -2.00(27) 10-6, and Y02 = -1.93(11) 10-8 for 79Br2 (all in cm-1, and 3? in parentheses). The single rovibronic fluorescence spectrum of the D(0u+) state shows a transition terminating on the X1?g+ ground state, and establishes the absolute v' numbering on the basis of the Franck-Condon factor calculations. The v' = 2 and 3 levels of the D(0u+) state are strongly perturbed due to the heterogeneous interaction with the 1u state correlating with the same ionic products of the D(0u+) state at the dissociation limit, Br-(1S) + Br+(3P2).

Ishiwata, Takashi; Tokunaga, Atsuto; Shinzawa, Tsutomu; Tanaka, Ikuzo

1984-12-01

272

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

273

Comparability of composition of carbon functional groups in humic acids between inverse-gated decoupling and cross polarization/magic angle spinning 13C nuclear magnetic resonance techniques.  

PubMed

To find a certain relation between the composition of carbon functional groups of humic acids derived from liquid state (13)C nuclear magnetic resonance (NMR) spectra acquired with inverse-gated decoupling (IGD), known as a quantitative pulse sequence, and that by solid-state (13)C NMR with cross polarization/magic angle spinning (CPMAS) techniques, fifteen soil humic acid samples with a wide range of aromaticity were analyzed. Relationships between the proportions of humic acid carbon as alkyl, O-alkyl, and aromatic carbon assessed by the two methods could be regressed to y=ax (r=0.932-0.956; P<0.005), respectively. The contents of alkyl, O-alkyl, and aromatic carbon assessed by CPMAS method were larger than those found by IGD method. However, the differences between the two methods were small and exclusive regression to y=x was also significant (r=0.775-0.941; P<0.005). Aromaticity calculated from (13)C CPMAS NMR data also did not differ significantly from those computed from (13)C NMR spectra with IGD. These observations indicated the comparability of the relative content of carbon functional groups in humic acids except for carboxyl and carbonyl carbon. PMID:18501252

Watanabe, Akira; Fujitake, Nobuhide

2008-04-26

274

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

275

Calculation of the nuclear quadrupole resonance spectra of YBa/sub 2/Cu/sub 3/O/sub 7/minus/x/  

SciTech Connect

Nuclear quadrupole resonance (NQR) and nuclear magnetic resonance (NMR) studies on /sup 63,65/Cu have demonstrated the the resonance properties of these nuclei can give important information about the electronic structure of the high temperature superconductor YBa/sub 2/Cu/sub 3/O/sub 7/minus/x/ as well as the exchange coupling energy between the Cu(2) sites. Measurements for various oxygen stoichiometries have given insight into the effect of oxygen content on the valence state of the Cu. In the work reported here, the electric field gradient (EFG) tensors at the Cu(1) and Cu(2) sites in YBa/sub 2/Cu/sub 3/O/sub 7/minus/x/, have been determined from calculations on large clusters for x = 0 and 1. 13 refs., 2 tabs.

Winter, N.W.; Violet, C.E.

1989-06-01

276

P3H-4 The Finite Element Analysis of Quartz Crystal Resonators with Mindlin Plate Theory and Parallel Computing Techniques on Computer Clusters  

Microsoft Academic Search

The accurate analysis of high frequency vibrations of quartz crystal resonators are increasingly critical in product design and development because the miniaturization has signified effects of complications such as electrodes, beveling, and mountings, which affect the resonator performance through key indicators like the frequency-temperature characteristics and quality factor. The practical solutions are available from finite element analysis based on the

Ji Wang; Wenke Hu; Wenhua Zhao; Jianke Du; Dejin Huang

2007-01-01

277

Effect of the gas mixing technique on the plasma potential and emittance of the JYFL 14 GHz electron cyclotron resonance ion source  

SciTech Connect

The effect of the gas mixing technique on the plasma potential, energy spread, and emittance of ion beams extracted from the JYFL 14 GHz electron cyclotron resonance ion source has been studied under various gas mixing conditions. The plasma potential and energy spread of the ion beams were studied with a plasma potential instrument developed at the Department of Physics, University of Jyvaeskylae (JYFL). With the instrument the effects of the gas mixing on different plasma parameters such as plasma potential and the energy distribution of the ions can be studied. The purpose of this work was to confirm that ion cooling can explain the beneficial effect of the gas mixing on the production of highly charged ion beams. This was done by measuring the ion-beam current as a function of a stopping voltage in conjunction with emittance measurements. It was observed that gas mixing affects the shape of the beam current decay curves measured with low charge-state ion beams indicating that the temperature and (or) the spatial distribution of these ions is affected by the mixing gas. The results obtained in the emittance measurements support the conclusion that the ion temperature changes due to the gas mixing. The effect of the energy spread on the emittance of different ion beams was also studied theoretically. It was observed that the emittance depends considerably on the dispersive matrix elements of the beam line transfer matrix. This effect is due to the fact that the dipole magnet is a dispersive ion optical component. The effect of the energy spread on the measured emittance in the bending plane of the magnet can be several tens of percent.

Tarvainen, O.; Suominen, P.; Ropponen, T.; Kalvas, T.; Heikkinen, P.; Koivisto, H. [Department of Physics, Accelerator Laboratory, University of Jyvaeskylae, P.O. Box 35, FIN-40014 University of Jyvaeaskylae (Finland)

2005-09-15

278

Direct measurement of the accumulation and mitochondrial conversion of nitric oxide within Chinese hamster ovary cells using an intracellular electron paramagnetic resonance technique.  

PubMed

We have developed an electron paramagnetic resonance (EPR) method for the nondestructive detection and quantification of intracellular NO in real time. Based upon this technique, we have obtained evidence for the metabolism of this bioregulatory molecule by mitochondria. Line-broadening of the EPR signal of a coal derivative, fusinite, was calibrated as a function of NO concentration in aqueous solution. The methodology was validated using two compounds which release NO in a controlled and predictable manner with first-order rate constants k1 = 5.0 x 0.10(-3) s-1 and k'1 = 3.4 x 10(-4) s-1 (35 degrees C). Fusinite was internalized in Chinese hamster ovary cells (CHO) by phagocytosis, after which the cells were allowed to consume the available O2, producing an hypoxic environment. The NO released from one of the NO donors, added to the culture fluid at an initial concentration of 50 microM, was directly measured in the intracellular environment as line-broadening of the fusinite EPR signal. The linewidth diminished with time, indicating that NO was being converted to a non-paramagnetic species by the cells with an apparent zero-order rate constant of 5 x 10(8) NO molecules cell-1 min-1 (20 degrees C). Addition of cyanide to the culture medium (5 mM final concentration) inhibited this disappearance of NO. NO also was converted in the presence of isolated mitochondria in the absence of oxygen. These observations suggest that under hypoxic conditions, there exists in CHO cells a metabolic pathway for the conversion of NO to diamagnetic species, which involves interactions with mitochondria. PMID:7727525

Clarkson, R B; Norby, S W; Smirnov, A; Boyer, S; Vahidi, N; Nims, R W; Wink, D A

1995-04-13

279

Cardiovascular magnetic resonance of myocardial edema using a short inversion time inversion recovery (STIR) black-blood technique: Diagnostic accuracy of visual and semi-quantitative assessment  

PubMed Central

Background The short inversion time inversion recovery (STIR) black-blood technique has been used to visualize myocardial edema, and thus to differentiate acute from chronic myocardial lesions. However, some cardiovascular magnetic resonance (CMR) groups have reported variable image quality, and hence the diagnostic value of STIR in routine clinical practice has been put into question. The aim of our study was to analyze image quality and diagnostic performance of STIR using a set of pulse sequence parameters dedicated to edema detection, and to discuss possible factors that influence image quality. We hypothesized that STIR imaging is an accurate and robust way of detecting myocardial edema in non-selected patients with acute myocardial infarction. Methods Forty-six consecutive patients with acute myocardial infarction underwent CMR (day 4.5, +/- 1.6) including STIR for the assessment of myocardial edema and late gadolinium enhancement (LGE) for quantification of myocardial necrosis. Thirty of these patients underwent a follow-up CMR at approximately six months (195 +/- 39 days). Both STIR and LGE images were evaluated separately on a segmental basis for image quality as well as for presence and extent of myocardial hyper-intensity, with both visual and semi-quantitative (threshold-based) analysis. LGE was used as a reference standard for localization and extent of myocardial necrosis (acute) or scar (chronic). Results Image quality of STIR images was rated as diagnostic in 99.5% of cases. At the acute stage, the sensitivity and specificity of STIR to detect infarcted segments on visual assessment was 95% and 78% respectively, and on semi-quantitative assessment was 99% and 83%, respectively. STIR differentiated acutely from chronically infarcted segments with a sensitivity of 95% by both methods and with a specificity of 99% by visual assessment and 97% by semi-quantitative assessment. The extent of hyper-intense areas on acute STIR images was 85% larger than those on LGE images, with a larger myocardial salvage index in reperfused than in non-reperfused infarcts (p = 0.035). Conclusions STIR with appropriate pulse sequence settings is accurate in detecting acute myocardial infarction (MI) and distinguishing acute from chronic MI with both visual and semi-quantitative analysis. Due to its unique technical characteristics, STIR should be regarded as an edema-weighted rather than a purely T2-weighted technique.

2012-01-01

280

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.

281

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

Microsoft Academic Search

¹³⁹La nuclear quadrupole resistance (NQR) and relaxation measurements in lightly hole-doped La{sub 1.8-x}Eu{sub 0.2}SrCuO have been used to investigate the microscopic properties of the low-temperature orthorhombic to low-temperature tetragonal transition. The transition is characterized by a sharp peak in ¹³⁹La NQR relaxation rate, indicating phonon softening. We find that the structural phase transition is accompanied by a modification of the

B. J. Suh; P. C. Hammel; M. Huecker; B. Buechner

1999-01-01

282

Development of a New Type of Digitally Controlled Pulsed NMR Spectrometer Mainly Intended for Application of Fourier Multipulse and Double Resonance Techniques.  

National Technical Information Service (NTIS)

The construction of a variable frequency high power NMR spectrometer for use in Fourier transformation, multipulse sequences, and double resonance experiments is reported. Electronic components consist of fully transistorized broadband drivers for both me...

B. Knuettel

1977-01-01

283

Whole-body three-dimensional contrast-enhanced magnetic resonance (MR) angiography with parallel imaging techniques on a multichannel MR system for the detection of various systemic arterial diseases  

Microsoft Academic Search

Using a 1.5-T magnetic resonance (MR) imager equipped with 32 receiving channels and integrated parallel acquisition techniques,\\u000a 37 patients underwent whole-body three-dimensional (3D) contrast-enhanced MR angiography (WB 3D CE MRA). The patients included\\u000a had clinically documented or suspected peripheral arterial occlusive disease (PAOD, n = 19), Takayasu arteritis (n = 8), polyarteritis nodosa (n = 1), type-B dissection (n =

Jiang Lin; Bin Chen; Jian-Hua Wang; Meng-Su Zeng; Yi-Xiang Wang

2006-01-01

284

Innovative surface characterization techniques applied to immunosensor elaboration and test: Comparing the efficiency of Fourier transformsurface plasmon resonance, quartz crystal microbalance with dissipation measurements, and polarization modulationreflection absorption infrared spectroscopy  

Microsoft Academic Search

Three sensitive and original transduction techniques have been used to monitor the immobilization of anti-rabbit immunoglobulins (anti-rIgGs) and the detection of rIgGs on gold transducers. Polarization modulationreflection absorption infrared spectroscopy (PMRAIRS), quartz crystal microbalance with dissipation measurements (QCMD), and Fourier transformsurface plasmon resonance (FTSPR) were combined to achieve the best sensitivity and a large dynamic range in the target detection

Souhir Boujday; Christophe Mthivier; Bruno Beccard; Claire-Marie Pradier

2009-01-01

285

Supramolecular synthon pattern in solid clioquinol and cloxiquine (APIs of antibacterial, antifungal, antiaging and antituberculosis drugs) studied by 35 Cl NQR, 1 H- 17 O and 1 H- 14 N NQDR and DFT\\/QTAIM  

Microsoft Academic Search

The quinolinol derivatives clioquinol (5-chloro-7-iodo-8-quinolinol, Quinoform) and cloxiquine (5-chloro-8-quinolinol) were\\u000a studied experimentally in the solid state via 35Cl NQR, 1H-17O and 1H-14N NQDR spectroscopies, and theoretically by density functional theory (DFT). The supramolecular synthon pattern of OHN\\u000a hydrogen bonds linking dimers and ?? stacking interactions were described within the QTAIM (quantum theory of atoms in molecules)\\u000a \\/DFT (density functional theory)

Jolanta Natalia Latosi?ska; Magdalena Latosi?ska; Marzena Agnieszka Tomczak; Janez Seliger; Veselko agar

286

209Bi NMR and NQR investigation of the small-gap semiconductor Ce3Bi4Pt3  

Microsoft Academic Search

We report measurements of the temperature dependence of the 209Bi nuclear quadrupole resonance frequency nuQ, the Knight shift K, and the spin-lattice relaxation rate 1\\/T1 in the small-gap semiconductor Ce3Bi4Pt3 between 1.8 and 300 K. Corresponding measurements also are reported for the nonmagnetic metallic isomorph La3Bi4Pt3. The nuQ data in the Ce compound show a characteristic departure from metallic-to-insulating behavior

A. P. Reyes; R. H. Heffner; P. C. Canfield; J. D. Thompson; Z. Fisk

1994-01-01

287

Clinical assessment of ischemia and malignancy with magnetic resonance spectroscopy  

Microsoft Academic Search

Summary form only given. Using recent developments in construction of high field magnets, magnetic resonance spectroscopy has been integrated with magnetic resonance imaging for clinical use. Magnetic resonance (MR) spectra can be obtained from an image-defined volume of interest using a variety of magnetic resonance localization techniques. Recently, magnetic resonance spectroscopic imaging techniques have been developed which fully combine MR

M. W. Weiner

1988-01-01

288

Electrostatic (plasmon) resonances in nanoparticles  

NASA Astrophysics Data System (ADS)

A surface integral eigenvalue based technique for the direct calculation of resonance values of the permittivity of nanoparticles, and hence resonance frequencies, is discussed. General physical properties of electrostatic (plasmon) resonances are presented. Strong orthogonality properties of resonance modes, a two-dimensional phenomenon of twin spectrum and explicit estimates of resonance frequencies in terms of geometrical characteristics of convex nanoparticles are reported. Second-order corrections for resonance values of the dielectric permittivity are derived. Tunability and optical controllability of plasmon resonances in semiconductor nanoparticles are discussed and, as a digression, a plausible plasmon resonance mechanism for nucleation and formation of ball lightning is outlined. An efficient numerical algorithm for the calculation of resonance frequencies is developed and illustrated by extensive computational results that are compared with theoretical results and available experimental data.

Mayergoyz, Isaak D.; Fredkin, Donald R.; Zhang, Zhenyu

2005-10-01

289

NMR and NQR studies of the heavy fermion superconductors CeTIn{sub 5} (T=Co and Ir)  

SciTech Connect

We have carried out {sup 115}In and {sup 59}Co nuclear quadrupole resonance and nuclear magnetic resonance measurements on CeCoIn{sub 5} and CeIrIn{sub 5}. The temperature T dependence of the nuclear spin-lattice relaxation rate 1/T{sub 1} of {sup 115}In in the normal state indicates that CeCoIn{sub 5} is located just at an antiferromagnetic instability, and CeIrIn{sub 5} is in the nearly antiferromagnetic region. In the superconducting state, 1/T{sub 1} has no Hebel-Slichter coherence peak just below T{sub C} and a power-law T dependence (close to T{sup 3}) at very low temperatures, which indicates the existence of line nodes in the superconducting energy gap. The {sup 115}In (Ce-In plane) Knight shift in CeCoIn{sub 5} decreases for both parallel and perpendicular directions to the tetragonal c axis in the superconducting state, which shows that the spin susceptibility decreases in all directions. These results indicate that CeCoIn{sub 5} and CeIrIn{sub 5} exhibit non-s-wave even parity (probably d-wave) superconductivity.

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

2001-10-01

290

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

291

Numerical analysis of plasmon resonances in nanoparticles  

Microsoft Academic Search

Plasmon (electrostatic) resonances in nanoparticles are treated as an eigenvalue problem for a specific boundary integral equation. This leads to direct calculation of resonance values of permittivity and resonance frequency. The numerical technique is illustrated by examples of calculation of resonance frequencies for three-dimensional nanoparticles

Isaak D. Mayergoyz; Zhenyu Zhang

2006-01-01

292

Study on the interaction between hematoporphyrin monomethyl ether and DNA and the determination of hematoporphyrin monomethyl ether using the resonance light scattering technique  

Microsoft Academic Search

The interaction between photosensitizer anticancer drug hematoporphyrin monomethyl ether (HMME) and ctDNA has been studied based on the decreased resonance light scattering (RLS) phenomenon. The RLS, UVvis and fluorescence spectra characteristics of the HMMEctDNA system were investigated. Besides, the phosphodiesters quaternary ammonium salt (PQAS), a kind of new gemini surfactant synthesized recently, was used to determine anticancer drug HMME based

Zhanguang Chen; Tianhe Song; Xi Chen; Shaobin Wang; Junhui Chen

2010-01-01

293

Assessment of the ''thermal normalization technique'' for measurement of neutron cross sections vs energy. [Above 20 keV, resonance, fission integrals, error minimization  

Microsoft Academic Search

Refined knowledge of the thermal neutron cross sections of the fissile nuclides and of the (n,..cap alpha..) reaction standards, together with the reasonably well known energy dependence of the latter, have permitted resonance-region and low-keV fissile nuclide cross sections to be based on these standards together with count-rate ratios observed as a function of energy using a pulsed ''white'' source.

R. W. Peelle; G. de Sassure

1977-01-01

294

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 NaxCoO2yHO, 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; Mnsson, 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

295

209Bi NMR and NQR investigation of the small-gap semiconductor Ce3Bi4Pt3  

NASA Astrophysics Data System (ADS)

We report measurements of the temperature dependence of the 209Bi nuclear quadrupole resonance frequency ?Q, the Knight shift K, and the spin-lattice relaxation rate 1/T1 in the small-gap semiconductor Ce3Bi4Pt3 between 1.8 and 300 K. Corresponding measurements also are reported for the nonmagnetic metallic isomorph La3Bi4Pt3. The ?Q data in the Ce compound show a characteristic departure from metallic-to-insulating behavior when the sample is cooled below TM=80 K, the temperature of the susceptibility maximum, attributable to a loss of low-frequency vibrational modes in the insulating state. The Knight shift has both isotropic and axial components; this anisotropy originates from the presence of Ce via a transferred hyperfine coupling between Ce 4f and conduction electrons. An s-f exchange constant >=0.4 eV is found, consistent with hybridization in other rare-earth intermetallic compounds. A change in the scaling between the susceptibility and both the isotropic and axial Knight shifts at temperature TM provides evidence that hybridization between the Ce 4f orbitals and the conduction electrons is responsible for the gap structure. The temperature dependence of the 1/T1 data is consistent with a model electronic density of states possessing a temperature-independent gap ? of 180 K and a bandwidth of the order of 1600 K. The temperature dependence of 1/T1 can also be fit well with a temperature-dependent gap with ?(0) also ~=180 K.

Reyes, A. P.; Heffner, R. H.; Canfield, P. C.; Thompson, J. D.; Fisk, Z.

1994-06-01

296

Magnetic Resonance Spectroscopy in Biological Systems.  

National Technical Information Service (NTIS)

These notes give a general view of the various methods of magnetic resonance spectroscopy and of their possible applications to biological and medical problems. After analyzing the fundamental NMR and EPR techniques, double resonance (ENDOR), pulsed NMR a...

E. Tiezzi

1971-01-01

297

Binding investigation on the interaction between Methylene Blue (MB)/TiO2 nanocomposites and bovine serum albumin by resonance light-scattering (RLS) technique and fluorescence spectroscopy.  

PubMed

The interaction between Methylene Blue (MB)/TiO2 nanocomposites and bovine serum albumin (BSA) was investigated by resonance light scattering (RLS), fluorescence, three-dimension spectra and UV-vis absorbance spectroscopy. Several factors which may influence the RLS intensity were also investigated before characterizing MB/TiO2-BSA complex. It was proved that the mechanism of MB/TiO2 nanocomposites binding to BSA was mainly a result of the formation of MB/TiO2-BSA complex. The binding constant of MB/TiO2-BSA is 0.76210(-5)Lmol(-1) at 298K. By calculating the binding constant at different temperature, the thermodynamic parameters ?H, ?G, and ?S can be observed and deduced that the hydrophobic interactions played an important role to stabilize the complex. The distance r (3.73nm) between donor (BSA) and acceptor (MB/TiO2) was obtained according to fluorescence resonance energy transfer (FRET). The binding site for MB/TiO2 on BSA was mainly located in sub-domain IIA. The UV-vis absorbance, circular dichroism and three dimension fluorescence have also been used to investigate the effect of MB/TiO2 on the conformation of BSA. PMID:23985421

Li, Yuesheng; Zhang, Yue; Sun, Shaofa; Zhang, Aiqing; Liu, Yi

2013-08-08

298

Nuclear magnetic resonance contrast agents  

DOEpatents

This invention relates to the field of nuclear magnetic resonance imaging and nuclear magnetic resonance spectroscopy, also known simply as magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS). MRI and MRS are particularly useful in medical research and diagnosis. MRI may be used in addition to x-ray imaging. This invention concerns 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. 2 figs.

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

1989-01-24

299

Isothermal target and signaling probe amplification method, based on a combination of an isothermal chain amplification technique and a fluorescence resonance energy transfer cycling probe technology.  

PubMed

An iTPA (isothermal target and signaling probe amplification) method for the quantitative detection of nucleic acids, based on a combination of novel ICA (isothermal chain amplification) and fluorescence resonance energy transfer cycling probe technology (FRET CPT), is described. In the new ICA method, which relies on the strand displacement activity of DNA polymerase and the RNA degrading activity of RNase H, two displacement events occur in the presence of four specially designed primers. This phenomenon leads to powerful amplification of target DNA. Since the amplification is initiated only after hybridization of the four primers, the ICA method leads to high specificity for the target sequence. As part of the new ICA method, iTPA is achieved by incorporating FRET CPT to generate multiple fluorescence signals from a single target molecule. Using the resulting dual target and signaling probe amplification system, even a single copy level of a target gene can be successfully detected and quantified under isothermal conditions. PMID:20575518

Jung, Cheulhee; Chung, Ji Won; Kim, Un Ok; Kim, Min Hwan; Park, Hyun Gyu

2010-07-15

300

Damping of cavity-mode resonances in PCB power-bus structures using lossy slot resonators  

Microsoft Academic Search

In this paper, a novel technique suppressing cavity- mode resonances in PCB power-bus structures by using lossy slot resonators is presented. Guidelines for an optimized damping of the modal resonances are specified, which are based on rules derived recently for an appropriate selection and placement of damping capacitors. The effectiveness of the presented damping technique is shown by simulations as

Matthias Hampe; Stefan Dickmann

2006-01-01

301

Resonances of sandwiched optical antenna  

Microsoft Academic Search

We calculate the resonant properties of the sandwiched triangle and bowtie antennas using finite difference time domain technique and compare with one-layer structures. The sandwiched antennas possess two tunable resonances corresponding to the symmetric and antisymmetric modes for dipole excitation, which can be understood by the hybridization of the plasmons supported by the two golden layers of the antennas. We

Lisheng Wang; Jiasen Zhang; Xiaofei Wu; Jing Yang; Qihuang Gong

2008-01-01

302

[Myelin and nuclear magnetic resonance].  

PubMed

MRI is one of the most important tools for the investigation of white matter diseases of the central nervous system. Other techniques based on the magnetic resonance phenomena (magnetization transfer imaging, diffusion imaging, magnetic resonance spectroscopy) have joined MRI to better caracterize certain diseases, understand their pathophysiology and follow their evolution. PMID:18033031

Tourbah, A; Dormont, D; Galanaud, D; Sedel, F; Lyon-Caen, O

2007-10-01

303

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

304

Nuclear Magnetic Resonance.  

National Technical Information Service (NTIS)

Nuclear Magnetic Resonance (NMR) is a new technique which has been introduced into the medical diagnostic imaging field. NMR is a method of imaging the body by exposing it to low-energy magnetic and radio-frequency fields. This process yields bio-chemical...

D. Watkins N. Netherton

1983-01-01

305

Nuclear magnetic resonance gyroscopes  

Microsoft Academic Search

Nuclear magnetic resonance gyroscopes (NMRGs) detect rotation as a shift in the Larmor precession frequency of nuclear spins. A review of the open literature on NMRGs is presented, which includes an introduction to the spectroscopic techniques that enable NMRGs and a discussion of the design details for several specific NMRGs that have been built.

E. A. Donley

2010-01-01

306

Nuclear Magnetic Resonance (NMR) Guidelines.  

National Technical Information Service (NTIS)

Nuclear Magnetic Resonance (NMR) is a medical diagnostic imaging technique that applies the atomic principles of magnetic spin to visualize and analyze disease states in bodily tissues. NMR differs from the radiological devices in that (a) it does not uti...

R. Halpern

1983-01-01

307

Morphological resonances for multicomponent immunoassays  

NASA Astrophysics Data System (ADS)

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.; Bronk, B. V.

1995-06-01

308

Chemically Polished High Frequency Resonators.  

National Technical Information Service (NTIS)

The upper frequency limit of quartz resonators is determined by the physical properties of quartz and restrictions imposed by processing techniques. More often than not, the processing limitations are reached long before the physical limitations. Mechanic...

W. P. Hanson

1983-01-01

309

Linear low-density polyethylene and zirconium phosphate nanocomposites: evidence from thermal, thermo-mechanical, morphological and low-field nuclear magnetic resonance techniques.  

PubMed

Lamellar alpha-zirconium phosphate was synthesized by direct precipitation and also directly expanded with octadecylamine, through alcoholic solution. To produce a nanocomposite, it was incorporated in linear low-density polyethylene in the molten state, using a counterrotating twin-screw extruder set at 170-190 degrees C and 100 rpm. The differential scanning calorimetry analysis revealed a decrease in the polyolefin melting temperature and crystallinity degree. The higher onset temperature of the zirconium phosphate modified with octadecylamine and linear low density polyethylene composite indicated an increasing of thermal stability and it suggests that some polyethylene chains entered into the filler's spacing. Dynamic-mechanical analysis evidenced an increase in both moduli (storage and loss). Wide-angle X-ray diffraction showed additional peaks--diffraction angles appeared in the region beneath 12 degrees--which were attributed to partial intercalation of polyethylene chains between filler interlamellar spacing. By hydrogen low-field nuclear magnetic resonance, the two low intensity relaxation time peaks shifted to higher values, strongly suggesting interaction between the octadecylamine and polymer matrix into the filler galleries. From these results, it may be postulated that a partially intercalated and/or exfoliated nanostructure in the zirconium phosphate modified with octadecylamine and linear low density polyethylene composite was achieved. PMID:23447930

Mendes, Luis C; Silva, Daniela F; Lino, Adan S

2012-12-01

310

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.

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

2010-01-01

311

[A new concept in imaging pelvic recurrence of curatively operated rectal carcinoma--image fusion of nuclear magnetic resonance tomography and anti-CEA immunoscintigraphy (SPECT): technique and clinical example].  

PubMed

We present a new technique of image fusion (IF) of magnetic resonance imaging (MRT) and anti-CEA-immunoscintigraphy (Behring 431/26) and single photon emission computed tomography (SPECT). We performed SPECT and MRT within 8 hours on the same day. Glucagon intravenously was used to reduce artefacts due to intestinal motility. Before image fusion we analysed the SPECT and MRT images independently of each other. The MRT and SPECT were connected by a local area network (LAN) to a Gateway computer, which is also used as a picture archive. There a program automatically starts, translates the MRT data from the ACR/NEMA format to the Elscint one and these data are sent for image fusion to the nuclear medicine computer Elscint SP1. By means of a clinical example we present anatomic concordant superimposition and explain the findings and the clinical value of our technique. This system and technique are equally applicable to other digital imaging investigations. By IF, on the basis of the certain evidence of the tracer depot of a pathological lesion diagnosed by MRT and the reliability of the anatomical assignment of a focal lesion diagnosed by SPECT, early detection of local recurrence after surgical treatment of rectal cancer, the correct localisation of recurrent disease and its distinction from non-malignant tissue becomes possible. This enables planning of further therapeutical strategies. PMID:8560891

Kronberger, L; Fueger, G F; Nicoletti, R; Ranner, G; Wiltgen, M; Stollberger, R; Graif, E; Urans, S; Hauser, H; Mischinger, H J

1995-01-01

312

Stochastic resonance  

NASA Astrophysics Data System (ADS)

Over the last two decades, stochastic resonance has continuously attracted considerable attention. The term is given to a phenomenon that is manifest in nonlinear systems whereby generally feeble input information (such as a weak signal) can be be amplified and optimized by the assistance of noise. The effect requires three basic ingredients: (i) an energetic activation barrier or, more generally, a form of threshold; (ii) a weak coherent input (such as a periodic signal); (iii) a source of noise that is inherent in the system, or that adds to the coherent input. Given these features, the response of the system undergoes resonance-like behavior as a function of the noise level; hence the name stochastic resonance. The underlying mechanism is fairly simple and robust. As a consequence, stochastic resonance has been observed in a large variety of systems, including bistable ring lasers, semiconductor devices, chemical reactions, and mechanoreceptor cells in the tail fan of a crayfish. In this paper, the authors report, interpret, and extend much of the current understanding of the theory and physics of stochastic resonance. They introduce the readers to the basic features of stochastic resonance and its recent history. Definitions of the characteristic quantities that are important to quantify stochastic resonance, together with the most important tools necessary to actually compute those quantities, are presented. The essence of classical stochastic resonance theory is presented, and important applications of stochastic resonance in nonlinear optics, solid state devices, and neurophysiology are described and put into context with stochastic resonance theory. More elaborate and recent developments of stochastic resonance theory are discussed, ranging from fundamental quantum properties-being important at low temperatures-over spatiotemporal aspects in spatially distributed systems, to realizations in chaotic maps. In conclusion the authors summarize the achievements and attempt to indicate the most promising areas for future research in theory and experiment.

Gammaitoni, Luca; Hnggi, Peter; Jung, Peter; Marchesoni, Fabio

1998-01-01

313

Determination of rhodium by resonance light-scattering technique coupled with solid phase extraction using Rh(III) ion-imprinted polymers as sorbent.  

PubMed

A resonance light-scattering method (RLS) for the determination of Rh(III) was initially developed, based on the reaction among Rh(III), WO4(2-) and ethylrhodamine B. The method possesses high sensitivity, but lacks selectivity. Therefore, a Rh(III) ion-imprinted polymer (IIP), prepared by precipitation polymerization using 2-(allylthio)nicotinic acid (ANA) as functional monomer, was used as sorbent to construct a ion-imprint based solid-phase extraction (IIP-SPE) method for separation of rhodium from complicated matrices prior to its determination by RLS. The experimental parameters affecting the extraction efficiency and selectivity of IIP-SPE were studied carefully. Under the optimal conditions, the IIP-SPE column with the enrichment factor (EF) of 10 could be used at least 20 times without decreasing its extraction recovery (above 90%) significantly. The calibration graph for the determination of rhodium by RLS coupled with IIP-SPE procedure was linear in the range of 0.06-1.5 ng mL(-1) with the detection limit of 0.024 ng mL(-1). There is no metal ions tested at the concentration below 10 ng mL(-1) interfered in the determination of 0.8 ng mL(-1) Rh(III). The proposed IIP-SPE-RLS method was successfully applied to the extraction and measurement of trace rhodium in catalyst, water and geochemical samples with the relative standard deviation (RSD) of less than 4.0% (n=4). PMID:23597998

Yang, Bing; Zhang, Ting; Tan, Wenxiang; Liu, Peng; Ding, Zhongtao; Cao, Qiue

2012-12-05

314

Dibaryon Resonances.  

National Technical Information Service (NTIS)

New degrees of freedom, like mesons and baryonic resonance on one band, or quarks and color on the other hand, can lead to possible exotic states of baryonic number 2. Large resonances have indeed been observed in both elastic and inelastic nucleon-nucleo...

B. Mayer

1987-01-01

315

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

316

Ferromagnetic resonance properties of LPE YIG films  

Microsoft Academic Search

This is the first report of the ferromagnetic resonance properties of thin single-crystal YIG films grown by liquid phase epitaxy techniques (LPE). The resonance linewidths of photoetched disks are close to that of bulk YIG for both parallel and perpendicular resonance without any annealing of the films. A new type of surface spin wave, localized at the air-film interface, is

RODNEY D. HENRY; PAUL J. BESSER; D. M. HEINZ; J. E. MEE

1973-01-01

317

Magnetic resonance image segmentation using semi-automated software for quantification of knee articular cartilage--initial evaluation of a technique for paired scans  

PubMed Central

Purpose Software-based image analysis is important for studies of cartilage changes in knee osteoarthritis (OA). This study describes an evaluation of a semi-automated cartilage segmentation software tool capable of quantifying paired images for potential use in longitudinal studies of knee OA. We describe the methodology behind the analysis and demonstrate its use by determination of testretest analysis precision of duplicate knee magnetic resonance imaging (MRI) data sets. Methods Testretest knee MR images of 12 subjects with a range of knee health were evaluated from the Osteoarthritis Initiative (OAI) pilot MR study. Each subject was removed from the magnet between the two scans. The 3D DESS (sagittal, 0.456 mm0.365 mm, 0.7 mm slice thickness, TR 16.5 ms, TE 4.7 ms) images were obtained on a 3-T Siemens Trio MR system with a USA Instruments quadrature transmitreceive extremity coil. Segmentation of one 3D-image series was first performed and then the corresponding retest series was segmented by viewing both image series concurrently in two adjacent windows. After manual registration of the series, the first segmentation cartilage outline served as an initial estimate for the second segmentation. We evaluated morphometric measures of the bone and cartilage surface area (tAB and AC), cartilage volume (VC), and mean thickness (ThC.me) for medial/lateral tibia (MT/LT), total femur (F) and patella (P). Testretest reproducibility was assessed using the root-mean square coefficient of variation (RMS CV%). Results For the paired analyses, RMS CV % ranged from 0.9% to 1.2% for VC, from 0.3% to 0.7% for AC, from 0.6% to 2.7% for tAB and 0.8% to 1.5% for ThC.me. Conclusion Paired image analysis improved the measurement precision of cartilage segmentation. Our results are in agreement with other publications supporting the use of paired analysis for longitudinal studies of knee OA.

Brem, M. H.; Lang, P. K.; Neumann, G.; Schlechtweg, P. M.; Schneider, E.; Jackson, R.; Yu, J.; Eaton, C. B.; Hennig, F. F.; Yoshioka, H.; Pappas, G.; Duryea, J.

2010-01-01

318

Zero field NMR and NQR  

SciTech Connect

Methods are described and demonstrated for detecting the coherent evolution of nuclear spin observables in zero magnetic field with the full sensitivity of high field NMR. The principle motivation is to provide a means of obtaining solid state spectra of the magnetic dipole and electric quadrupole interactions of disordered systems without the line broadening associated with random orientation with respect to the applied magnetic field. Comparison is made to previous frequency domain and high field methods. A general density operator formalism is given for the experiments where the evolution period is initiated by a sudden switching to zero field and is terminated by a sudden restoration of the field. Analytical expressions for the signals are given for a variety of simple dipolar and quadrupolar systems and numerical simulations are reported for up to six coupled spin-1/2 nuclei. Experimental results are reported or reviewed for /sup 1/H, /sup 2/D, /sup 7/Li, /sup 13/C, and /sup 27/Al nuclei in a variety of polycrystalline materials. The effects of molecular motion and bodily sample rotation are described. Various extensions of the method are discussed, including demagnetized initial conditions and correlation by two-dimensional Fourier transformation of zero field spectra with themselves or with high field spectra.

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

1985-11-15

319

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 ...

320

Diffusion tensor imaging characterization of occult brain damage in relapsing neuromyelitis optica using 3.0T magnetic resonance imaging techniques.  

PubMed

Studies of relapsing neuromyelitis optica (RNMO) using advanced MRI techniques are limited compared with those done on multiple sclerosis (MS). The present study used diffusion tensor imaging (DTI) to investigate whether occult brain damage exists in RNMO patients. DTI scans using a 3.0T MRI scanner were performed in 24 clinically confirmed RNMO patients whose conventional brain MRI results were normal, and also in 24 age- and sex-matched healthy control subjects. DTI data were processed to generate fractional anisotropy (FA) and mean diffusivity (MD) maps, and region of interest (ROI) analyses were performed to obtain these parameters in white matter (including medulla oblongata, cerebral peduncle, optic radiation, genu of corpus callosum, splenium of corpus callosum, and internal capsule) and gray matter (including thalamus and putamen). Regional measures from patients at stable and acute phases were compared with healthy controls. Both acute and stable NMO patients had a higher average FA in ROIs of the thalamus and putamen. Acute NMO patients had significantly higher average MDs than controls in the genu of corpus callosum and optic radiation, and significantly lower average MDs in the medulla oblongata. Stable NMO patients had increased MDs in the genu of corpus callosum and optic radiation, but lower MDs in the medulla oblongata, internal capsule and thalamus. The DTI findings confirm the presence of occult tissue damage in normal-appearance white and gray matter, especially deep gray matter, in RNMO patients. This study adds further to the evidence that DTI is suitable as a tool for characterizing subtle brain tissue damage. PMID:22108642

Zhao, Dai-Di; Zhou, Hong-Yu; Wu, Qi-Zhu; Liu, Ju; Chen, Xiu-Ying; He, Dian; He, Xiao-Fei; Han, Wen-Jie; Gong, Qi-Yong

2011-11-13

321

Neuronal current distribution imaging using magnetic resonance  

Microsoft Academic Search

A new functional magnetic resonance imaging (fMRI) technique to visualize the distribution of neuronal currents in the human brain was developed Measurements of the internal magnetic field deformation caused by an electric current dipole in a phantom were performed using a method based on the microscopic magnetic resonance imaging technique. The minimal value of the current dipole moment detected by

Hirotake Kamei; Keiji Iramina; K. Yoshikawa; Shoogo Ueno

1999-01-01

322

Magnetic resonance arthrography of the upper extremity.  

PubMed

Although magnetic resonance arthrography is not indicated for every clinical scenario, capsular distention can significantly improve visualization of intra-articular pathologic conditions. With attention to technique, intraarticular injection can be completed successfully with little patient discomfort. This article provides details of the technique for injection of the shoulder, the elbow, and the wrist for optimization of magnetic resonance imaging. PMID:23472588

Lomasney, Laurie M; Choi, Haemi; Jayanthi, Neeru

2012-12-20

323

Probing spectroscopic like information using resonant scattering  

NASA Astrophysics Data System (ADS)

Resonant x-ray scattering can combine layer sensitivity of reflectivity technique with short-range structural sensitivity of absorption technique due to element specificity and contrast variation mechanism of resonant effect. We demonstrated the idea through depth profile study of chemical composition of multi-element thin film system at soft x-ray spectral range near boron K-absorption edge.

Nayak, M.; Lodha, G. S.

2012-06-01

324

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

325

Subthalamic nucleus deep brain stimulator placement using high-field interventional magnetic resonance imaging and a skull-mounted aiming device: technique and application accuracy  

PubMed Central

Object The authors discuss their method for placement of deep brain stimulation (DBS) electrodes using interventional MR (iMR) imaging and report on the accuracy of the technique, its initial clinical efficacy, and associated complications in a consecutive series of subthalamic nucleus (STN) DBS implants to treat Parkinson disease (PD). Methods A skull-mounted aiming device (Medtronic NexFrame) was used in conjunction with real-time MR imaging (Philips Intera 1.5T). Preoperative imaging, DBS implantation, and postimplantation MR imaging were integrated into a single procedure performed with the patient in a state of general anesthesia. Accuracy of implantation was assessed using 2 types of measurements: the radial error, defined as the scalar distance between the location of the intended target and the actual location of the guidance sheath in the axial plane 4 mm inferior to the commissures, and the tip error, defined as the vector distance between the expected anterior commissureposterior commissure (AC-PC) coordinates of the permanent DBS lead tip and the actual AC-PC coordinates of the lead tip. Clinical outcome was assessed using the Unified Parkinsons Disease Rating Scale part III (UPDRS III), in the off-medication state. Results Twenty-nine patients with PD underwent iMR imagingguided placement of 53 DBS electrodes into the STN. The mean ( SD) radial error was 1.2 0.65 mm, and the mean absolute tip error was 2.2 0.92 mm. The tip error was significantly smaller than for STN DBS electrodes implanted using traditional frame-based stereotaxy (3.1 1.41 mm). Eighty-seven percent of leads were placed with a single brain penetration. No hematomas were visible on MR images. Two device infections occurred early in the series. In bilaterally implanted patients, the mean improvement on the UPDRS III at 9 months postimplantation was 60%. Conclusions The authors technical approach to placement of DBS electrodes adapts the procedure to a standard configuration 1.5-T diagnostic MR imaging scanner in a radiology suite. This method simplifies DBS implantation by eliminating the use of the traditional stereotactic frame and the subsequent requirement for registration of the brain in stereotactic space and the need for physiological recording and patient cooperation. This method has improved accuracy compared with that of anatomical guidance using standard frame-based stereotaxy in conjunction with preoperative MR imaging.

Starr, Philip A.; Martin, Alastair J.; Ostrem, Jill L.; Talke, Pekka; Levesque, Nadja; Larson, Paul S.

2010-01-01

326

Magnetic resonance fingerprinting.  

PubMed

Magnetic resonance is an exceptionally powerful and versatile measurement technique. The basic structure of a magnetic resonance experiment has remained largely unchanged for almost 50?years, being mainly restricted to the qualitative probing of only a limited set of the properties that can in principle be accessed by this technique. Here we introduce an approach to data acquisition, post-processing and visualization--which we term 'magnetic resonance fingerprinting' (MRF)--that permits the simultaneous non-invasive quantification of multiple important properties of a material or tissue. MRF thus provides an alternative way to quantitatively detect and analyse complex changes that can represent physical alterations of a substance or early indicators of disease. MRF can also be used to identify the presence of a specific target material or tissue, which will increase the sensitivity, specificity and speed of a magnetic resonance study, and potentially lead to new diagnostic testing methodologies. When paired with an appropriate pattern-recognition algorithm, MRF inherently suppresses measurement errors and can thus improve measurement accuracy. PMID:23486058

Ma, Dan; Gulani, Vikas; Seiberlich, Nicole; Liu, Kecheng; Sunshine, Jeffrey L; Duerk, Jeffrey L; Griswold, Mark A

2013-03-14

327

Practical Use of a Simple Technique, Insertion of Wet Cotton Pledgets into the Tumor Resection Cavity in Transsphenoidal Surgery of Pituitary Tumors, for a Better Comparison between Pre- and Intraoperative High-Field Magnetic Resonance Images.  

PubMed

Background Intraoperative high-field magnetic resonance imaging (iMRI) is a useful modality for immediate intraoperative quality control. With iMRI, a surgeon can confirm whether tumor remnants exist during surgery; which makes it possible to add further resection, obtain a higher resection rate, and improve the cure rate. It is sometimes difficult to evaluate the existence of tumor remnants when the tumor resection cavity is collapsed. In this study, we reported a simple technique for comparing pre- and intraoperative MR images.Patients and Methods Thirty-five consecutive patients with pituitary adenoma underwent endoscopic endonasal transsphenoidal surgery using iMRI. Twenty-six patients had adenomas with suprasellar extension, and 9 had intrasellar adenomas. Nine adenomas had cavernous sinus invasion. Eight patients had endocrine-active, and 27 endocrine-inactive tumors. The simple technique included wet cotton pledgets inserted into the resection cavity to easily and precisely compare pre- and intraoperative MR images. Furthermore, we evaluated the efficacy of iMRI using our method on determining the extent of tumor resection in this study.Results The first iMRI scan showed that 12 of 35 patients had some tumor remnants, and 23 patients did not. Eight of these 12 patients with tumor remnants had cavernous sinus invasion. Three cases received further tumor resection after iMRI and had a gross total removal.Conclusions We presented our initial results after using a simple method in high-field iMRI during endoscopic transnasal transsphenoidal pituitary surgery. This procedure allowed us to obtain valuable information to determine the extent of tumor resection and to precisely visualize the parasellar structures. PMID:23929408

Kuge, Atsushi; Kikuchi, Zensho; Sato, Shinya; Sakurada, Kaori; Takemura, Sunao; Kayama, Takamasa

2013-08-08

328

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

329

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

330

Local distortions in the BiO6-octahedra sublattice of BaPbxBi1-xO3 as seen by a137Ba NMR/NQR  

NASA Astrophysics Data System (ADS)

The a137Ba NMR and NQR spectra as well as the spin-lattice relaxation rate were measured for the first time in the BaPbxBi1-xO3 samples with x = 0.91 (normal metal), x = 0.75 (superconductor) and x = 0.64 (semiconductor). The strong quadrupole broadening of the NMR lines with lowering temperature was found for all the samples. An evolution of static distortions in the BiO6-octahedra sublattice along with asymmetry of the electric field gradient at the Ba-sites is discussed. This asymmetry caused by the nearest non-cubic surrounding of barium is originated from the temperature dependent tilt of BiO6-octahedra. Spin-lattice relaxation rate of a137Ba is monitored by fluctuating part of electric field gradient at the Ba-site and its exponential growth at low temperatures evidences the thermally activated collective rotations of BiO6-octahedra around their static tilt. An activation energy and a strength of these dynamic distortions are evaluated and found to increase in going from metallic to semiconducting phase of BaPbxBi1-xO3.

Verkhovskii, S. V.; Gerashenko, A. P.; Zhdanov, Yu. I.; Mikhalev, K. N.; Sagaradze, I. V.; Medvedev, Eu. Yu.; Cheshnitskii, S. M.; Pletnev, R. N.; Kumagai, K.; Piskunov, Yu. V.; Yakubovskii, A. Yu.

1997-02-01

331

Temperature-Induced Change in the Magnitude of the Effective Density of States: A NQR/NMR Study of the A-Site-Ordered Perovskite System CaCu3Ru4O12  

NASA Astrophysics Data System (ADS)

NQR/NMR measurements, including spin-lattice relaxation rate (1/T1) and Knight shift (K) evaluations, have been carried out for Cu and Ru nuclear spins in the A-site ordered perovskite system CaCu3Ru4O12, which exhibits a mass-enhancement-like behavior although it possesses no f electrons. The temperature evolution of T1 for Cu, which was measured up to 700 K, exhibits 1/T1T = constant behavior at high enough temperatures. This clearly denies the existence of a Cu localized moment, which was previously suggested as the origin of the mass enhancement in a dense Kondo scenario. Furthermore, K and (1/T1T) for Cu exhibit significant temperature dependences with two characteristic temperatures TF=20 K and TX=180 K, suggesting a temperature-induced transition of microscopic electronic character at TF and TX. We propose a two-band model, where the effective density of states for one of the bands shows a significant temperature dependence in TF

Kato, Harukazu; Tsuruta, Takuya; Matsumura, Masahiro; Nishioka, Takashi; Sakai, Hironori; Tokunaga, Yo; Kambe, Shinsaku; Walstedt, Russell E.

2009-05-01

332

Determination of the Parameters of the Electric Field Gradient Tensor for Nuclei with Half Integral Spin from Zeeman-Split NQR Spectra  

Microsoft Academic Search

A new method is proposed for determining the magnitude of the coupling constant, the asymmetry parameter and the orientation of the principal axes of the electric field gradient tensor at the site of a quadrupole nucleus with half integral spin. A function is constructed from the first order splitting of the nuclear quadrupole resonance absorption line produced by a small

S. Sengupta; R. Roy; A. K. Saha

1972-01-01

333

Enhanced spin fluctuations in the As-based filled skutterudite LaFe4As12 : A L139a NMR and A75s NQR study  

NASA Astrophysics Data System (ADS)

We have grown single crystals of the itinerant-electron weak ferromagnet LaFe4As12 (TC=3.8K) and refined its crystal structure parameters. We report experimental results of magnetic susceptibility and nuclear magnetic resonance at the La site and nuclear quadrupole resonance at the As site in the paramagnetic state for this compound. The temperature dependences of the static magnetic susceptibility, the L139a Knight shift, and the reciprocal of the product of the spin-lattice relaxation time and temperature (1/T1T) of both L139a and A75s nuclei can be consistently understood in terms of self-consistent renormalization theory of spin fluctuations for weak itinerant-electron ferromagnets.

Nowak, B.; ?oga?, O.; Pietraszko, A.; Baumbach, R. E.; Maple, M. B.; Henkie, Z.

2009-06-01

334

Cl-NQR study of the structural order-disorder transition in (CH3NH3)2MnCl4  

Microsoft Academic Search

The temperature dependence of the Cl nuclear quadrupole resonance for the two chemically inequivalent chlorine sites in the perovskitic layer structure compound (CH3NH3)2 MnCl4 has been measured around the second order phase transition at 393.7 K. A value of the critical exponent ? of the order parameter was determined to be ? = 0.250 0.005 which is intermediate between

R. Kind; J. Roos

1976-01-01

335

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

336

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

337

Magnetic resonance imaging of acquired cardiac disease.  

PubMed Central

Over the last 15 years, advances in magnetic resonance imaging techniques have increased the accuracy and applicability of cardiovascular magnetic resonance imaging. These advances have improved the utility of magnetic resonance imaging in evaluating cardiac morphology, blood flow, and myocardial contractility, all significant diagnostic features in the evaluation of the patient with acquired heart disease. Utilization of cardiovascular magnetic resonance imaging has been limited, primarily due to clinical reliance upon nuclear scintigraphy and echocardiography. Recent developments in fast and ultrafast imaging should continue to enhance the significance of magnetic resonance imaging in this field. Widespread use of magnetic resonance imaging in the evaluation of the cardiovascular system will ultimately depend upon its maturation into a comprehensive, noninvasive imaging technique for the varying manifestations of acquired heart disease, including cardiomyopathy, ischemic heart disease, and acquired valvular disease. Images

Carrol, C L; Higgins, C B; Caputo, G R

1996-01-01

338

Bone tunnel enlargement after anterior cruciate ligament reconstruction with the hamstring autograft and endobutton fixation technique. A clinical, radiographic and magnetic resonance imaging study with 2 years follow-up.  

PubMed

The aim of this study was to describe the contrast-enhanced magnetic resonance imaging (MRI) appearance of bone tunnel enlargement detected on radiography after anterior cruciate ligament (ACL) reconstruction with semitendinosus and gracilis tendon endobutton (STG-endobutton) fixation technique. Fourteen patients with a STG-endobutton ACL reconstruction were examined 3 months (n = 1), 1 year (n = 1) and 2 years (n = 12) postoperatively. An age- and sex-matched group with a bone-patellar tendon-bone (BTB) autograft ACL reconstruction with similar follow-up was taken as control. Data on clinical examination, laxity and isokinetic muscle torque measurements, anteroposterior and lateral view radiography were obtained, and knee scores (Lysholm and Tegner) were collected. Contrast-enhanced MRI was performed in the STG-endobutton group with a 1.5-T imager. There were no statistical differences between the groups with respect to clinical findings, stability tests, or knee scores. In the STG-endobutton group the average femoral and tibial bone tunnel diameter detected on anteroposterior view radiography had increased at 2-year follow-up by 33% and 23%, respectively. On MRI the ligamentous graft itself was not enhanced by the contrast medium whereas periligamentous tissue within and around the STG graft bundles showed mild contrast enhancement. In conclusion, the MRI results suggest that enhancing periligamentous tissue accumulated in and around the STG graft associated with the tunnel expansion. In spite of the significant bone tunnel enlargement observed on the follow-up radiography the STG-endobutton knees were stable and the patients satisfied. PMID:10525698

Jansson, K A; Harilainen, A; Sandelin, J; Karjalainen, P T; Aronen, H J; Tallroth, K

1999-01-01

339

Thermal nonlinearity in silicon microcylindrical resonators  

NASA Astrophysics Data System (ADS)

We explore the thermally induced nonlinearity in hydrogenated amorphous silicon microcylindrical resonators that are fabricated from the silicon optical fiber platform. In particular, we use a pump-probe technique to experimentally demonstrate thermally induced optical modulation and determine the response time. Through characterization of the thermal properties and the associated resonance wavelength shifts, we will show that it is possible to infer the material absorption coefficient for a range of whispering gallery mode resonators.

Vukovic, Natasha; Healy, Noel; Mehta, Priyanth; Day, Todd D.; Sazio, Pier J. A.; Badding, John V.; Peacock, Anna C.

2012-04-01

340

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.

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

2011-01-01

341

Secular resonance in extrasolar system  

NASA Astrophysics Data System (ADS)

The two orbits in the HD 160691 planetary system at first appeared highly unstable, but using a new technique called MEGNO (the acronym of Mean Exponential Growth factor of Nearby Orbits), we were able to identify a stability valley in the parameter space. This stability zone is due to the 2:1 mean motion resonance coupled with relative orbital positions of the planets avoiding close approaches in the closeness of their periastron, the two apsidal lines being anti-aligned. The mechanism itself is preserved by librations of the mean motion resonance variables while the longitudes of periapse on average precess at the same rate. The secular resonance variable of the HD 160691 system librates around 180o while it librates around 0o in the Gliese 876 system. We present an extended study of such mechanisms to the Io-Europa pair and the planetary system HD 82943 in order to compare in details these four original cases of secular resonances associated to the 2:1 resonance (Io-Europa, Gliese 876, HD 82943, HD 160691). We concluded that in order to be dynamically stable, the extrasolar planetary systems close to the 2:1 mean motion resonance have to satisfy an apsidal secular resonance and apparently high eccentricities. Because of high eccentricities of the orbits, and despite their relatively small semi-major axes, the relative distances between the two planets may indeed remain sufficiently large over the whole evolutionary time scale of the system.

Rambaux, N.; Bois, E.

2003-04-01

342

All-resonant control of superconducting resonators.  

PubMed

An all-resonant method is proposed to control the quantum state of superconducting resonators. This approach uses a tunable artificial atom linearly coupled to resonators, and allows for efficient routes to Fock state synthesis, qudit logic operations, and synthesis of NOON states. This resonant approach is theoretically analyzed, and found to perform significantly better than existing proposals using the same technology. PMID:23215585

Strauch, Frederick W

2012-11-20

343

All-Resonant Control of Superconducting Resonators  

NASA Astrophysics Data System (ADS)

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

Strauch, Frederick W.

2012-11-01

344

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

Kerber, Robert C.

2006-01-01

345

Stochastic resonance in electrical circuits. I. Conventional stochastic resonance  

Microsoft Academic Search

Stochastic resonance (SR), a phenomenon in which a periodic signal in a nonlinear system can be amplified by added noise, is introduced and discussed. Techniques for investigating SR using electronic circuits are described in practical terms. The physical nature of SR, and the explanation of weak-noise SR as a linear response phenomenon, are considered. Conventional SR, for systems characterized by

Dmitrii G. Luchinsky; Riccardo Mannella; Peter V. E. McClintock; Nigel G. Stocks

1999-01-01

346

Resonance asymmetry induced bias errors in waveguide type optical passive resonator gyro.  

PubMed

We present an in-depth analysis of the resonance asymmetry in a silica waveguide ring resonator (WRR) and its influence on the waveguide-type optical passive resonator gyro (OPRG). A big bias error appears at the output of the OPRG. This big error is caused not only by the resonance asymmetry in the WRR, but also by the modulation parameters in the phase modulation spectroscopy technique (PMST). It has been proved that the bias error is proportional to the modulation frequency difference between the clockwise (CW) and counterclockwise (CCW) lightwaves. Three types of resonance asymmetries are thoroughly introduced and discussed. Methods to overcome the big bias error are demonstrated. A high reciprocal resonator is crucial to reduce the bias error. For a certain resonator, a proper temperature needs to be set to minimize the resonance asymmetry. A proper modulation frequency difference between the CW and CCW lightwaves is also helpful to reduce the bias error. PMID:22614414

Chen, Yan; Ma, Huilian; Jin, Zhonghe

2012-05-01

347

Advances in Magnetic Resonance Electrical Impedance Mammography  

Microsoft Academic Search

Magnetic Resonance Electrical Impedance Mammography (MREIM) is a new imaging technique under development by Wollin Ventures, Inc. in conjunction with the H. Lee Moffitt Cancer Center & Research Institute. MREIM addresses the problem of low specificity of magnetic resonance mammography and high false-positive rates, which lead to unnecessary biopsies. Because cancerous tissue has a higher electrical conductivity than benign tissue,

Nataliya Kovalchuk

2008-01-01

348

Polymer microring resonators and their sensor applications  

Microsoft Academic Search

Photonic microring resonators have great potential in the application of highly sensitive label-free biosensors and detection of high-frequency ultrasound due to high Q-factor resonances. Design consideration, device fabrication techniques, experimental results are report in this paper.

L. Jay Guo; Adam Maxwell; Chung-Yen Chao; Tao Ling; Jin-Sung Kim; Sheng-Wen Huang; Shai Ashkenazi

2008-01-01

349

An Active Microwave Filter with Dielectric Resonator  

Microsoft Academic Search

An active microwave filter has been newly developed by using dielectric resonators combined with active elements. The purpose of this paper is to describe about the new technique and the performance of the active filter at 6 GHz band. The value of the equivalent unloaded Q of the resonant element exceeds 37,000 in our experiment.

H. Matsumura; Y. Konishi

1979-01-01

350

Magnetic resonance imaging in medicine  

Microsoft Academic Search

Over the past twenty years, magnetic resonance imaging (MRI) has become one of the most important imaging modalities available to clinical medicine. It offers great technical flexibility, and is free of the hazards associated with ionizing radiation. In addition to its role as a routine imaging technique with a growing range of clinical applications, the pace of development in MRI

Stephen F. Keevil

2001-01-01

351

Secular resonance in extrasolar system  

Microsoft Academic Search

The two orbits in the HD 160691 planetary system at first appeared highly unstable, but using a new technique called MEGNO (the acronym of Mean Exponential Growth factor of Nearby Orbits), we were able to identify a stability valley in the parameter space. This stability zone is due to the 2:1 mean motion resonance coupled with relative orbital positions of

N. Rambaux; E. Bois

2003-01-01

352

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

353

Dendritic versus somatic resonance  

Microsoft Academic Search

Here, we investigate to what extent and under which circumstances cells with dendritic resonance may be misclassified as nonresonant by somatic measurement of resonance properties. We use simple conductance-based multicompartmental models to analyze the effect of dendritic resonance on somatic input (and hence resonance estimates based on somatic recordings). We find that indeed, even a strong dendritic resonance may not

Ekaterina A Zhuchkova; Susanne Schreiber

2011-01-01

354

Theory and applications of surface plasmon resonance, resonant mirror, resonant waveguide grating, and dual polarization interferometry biosensors.  

PubMed

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

2010-11-01

355

Resonant charging  

NASA Astrophysics Data System (ADS)

It has been shown (Athas et al., 1994) that adiabatic switching can significantly reduce the dynamic power dissipation in an integrated circuit. Due to the overhead in the realization of adiabatic logic blocks (Saas et al., 2000) the best results are achieved when it is used only for charging dominant loads in an integrated circuit (Voss and Glessner, 2001). It has been demonstrated (Saas et al., 2001) that a multi stage driver is needed for minimal power dissipation. In this article a complete three stage driver including the generation of oscillating supply is described. To obtain a minimal power dissipation during synchronization the resonant frequency has to be constant. Therefore the waveforms for the logic states of the signal and the realization of a single stage differ from those presented in (Saas et al., 2001). In the H-SPICE simulations losses of the inductor are taken into account. This allows to estimate the power reduction that is achievable in a real system.

Saas, C.; Nossek, J. A.

2003-05-01

356

CONUSS and PHOENIX: Evaluation of nuclear resonant scattering data  

Microsoft Academic Search

Evaluation methods for data obtained by nuclear resonant scattering techniques are discussed. The CONUSS software package for the interpretation of time or energy spectra from coherent elastic nuclear resonant scattering, i.e., forward scattering and Bragg\\/Laue scattering, is presented. The analysis of phonon spectra obtained by incoherent nuclear resonant scattering is demonstrated using the PHOENIX software.

W. Sturhahn

2000-01-01

357

Identification of resonance waves in open water channels  

Microsoft Academic Search

This article describes a way to determine the properties of resonance (reflecting) waves in open water channels. For channels that are sensitive to resonances, information about the first resonance mode is required for controller and filter design. This research applies standard system identification techniques and is tested on an actual channel at the Central Arizona Irrigation and Drainage District, Eloy,

P. J. van Overloop; I. J. Miltenburg; X. Bombois; A. J. Clemmens; R. J. Strand; N. C. van de Giesen; R. Hut

2010-01-01

358

The treatment of resonance interference effects in the subgroup method  

Microsoft Academic Search

This paper describes the development of a method to treat resonance interference effects within the framework of the subgroup method. The new procedure provides for the treatment of multiple resonance absorbers in which the subgroup weights are determined using a least squares technique and based on the cross sections generated from a mixture of multiple resonance isotopes and a suitably

Zhenjia Gao; Yunlin Xu; Thomas J. Downar

2011-01-01

359

Self-polarized capacitive silicon micromechanical resonators via charge trapping  

Microsoft Academic Search

We present for the first time a charge trapping technique as a viable passive biasing mechanism for capacitive silicon micromechanical resonators. Potential wells are created on the surface of the microresonator to trap charges for mimicking a polarization voltage (Vp) of 8 V. With no externally applied Vp, the resonance peak of a 20 ?m thick silicon bulk acoustic resonator

Ashwin K. Samarao; Farrokh Ayazi

2010-01-01

360

Photonic coherence phenomena in coupled optical resonators  

NASA Astrophysics Data System (ADS)

A structure consisting of N coupled optical resonators exhibits resonances that split into N higher-Q modes due to coherent coupling between resonators. This has a direct analogy with other types of oscillators. In particular, for two (or any even number of) coupled optical resonators, this mode splitting leads to a cancellation of absorption on resonance as a result of classical destructive interference of the symmetric and antisymmetric modes of the system. An analogy between this effect and electromagnetically-induced transparency in an atomic system is explored. Furthermore, a variety of photonic coherence phenomena in passive and active coupled optical resonators is investigated. Specifically, the effective dispersive and absorptive steady-state response of coupled resonators is derived and used to determine the conditions for coupled-resonator-induced transparency and absorption, lasing without gain, and cooperative cavity emission. These effects rely on coherent photon trapping, in direct analogy with coherent population trapping phenomena in atomic systems. It is also demonstrated that the coupled-mode equations are formally identical to the two-level atom Schrodinger equation in the rotating-wave approximation. The impulse response of coupled resonators is also derived. It is found that the coupled-resonator photon dynamics display damped Rabi oscillations, which facilitates adiabatic coherent photon transfer techniques such as stimulated Raman adiabatic passage. These effects are predicted directly from coupled-mode theory, and thus are not unique to atoms, but rather are fundamental to systems of coherently coupled resonators. It is also theoretically predicted that in coupled optical resonators slow and fast light can propagate without attenuation. In systems of coupled resonators, slow light can propagate without attenuation by a cancellation of absorption as a result of mode splitting and destructive interference, whereas transparent fast light propagation can be achieved with the assistance of gain and splitting of the intracavity resonances, which consequently switches the dispersion from normal to anomalous.

Chang, Hongrok

361

System and method for regulating resonant inverters  

DOEpatents

A technique is provided for direct digital phase control of resonant inverters based on sensing of one or more parameters of the resonant inverter. The resonant inverter control system includes a switching circuit for applying power signals to the resonant inverter and a sensor for sensing one or more parameters of the resonant inverter. The one or more parameters are representative of a phase angle. The resonant inverter control system also includes a comparator for comparing the one or more parameters to a reference value and a digital controller for determining timing of the one or more parameters and for regulating operation of the switching circuit based upon the timing of the one or more parameters.

Stevanovic, Ljubisa Dragoljub (Clifton Park, NY); Zane, Regan Andrew (Superior, CO)

2007-08-28

362

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

363

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

364

Resonant frequency of gold/polycarbonate hybrid nano resonators fabricated on plastics via nano-transfer printing  

NASA Astrophysics Data System (ADS)

We report the fabrication of gold/polycarbonate (Au/PC) hybrid nano resonators on plastic substrates through a nano-transfer printing (nTP) technique, and the parametric studies of the resonant frequency of the resulting hybrid nano resonators. nTP is a nanofabrication technique that involves an assembly process by which a printable layer can be transferred from a transfer substrate to a device substrate. In this article, we applied nTP to fabricate Au/PC hybrid nano resonators on a PC substrate. When an AC voltage is applied, the nano resonator can be mechanically excited when the AC frequency reaches the resonant frequency of the nano resonator. We then performed systematic parametric studies to identify the parameters that govern the resonant frequency of the nano resonators, using finite element method. The quantitative results for a wide range of materials and geometries offer vital guidance to design hybrid nano resonators with a tunable resonant frequency in a range of more than three orders of magnitude (e.g., 10 KHz-100 MHz). Such nano resonators could find their potential applications in nano electromechanical devices. Fabricating hybrid nano resonators via nTP further demonstrates nTP as a potential fabrication technique to enable a low-cost and scalable roll-to-roll printing process of nanodevices.

Dechaumphai, Edward; Zhang, Zhao; Siwak, Nathan P.; Ghodssi, Reza; Li, Teng

2011-12-01

365

Characterization of nitrides by electron paramagnetic resonance (EPR) and optically detected magnetic resonance (ODMR)  

Microsoft Academic Search

We will highlight our recent work on the properties of residual defects and dopants in GaN heteroepitaxial layers and on the nature of recombination from InGaN single quantum well (SQW) light emitting diodes (LEDs) through magnetic resonance techniques. Electron paramagnetic resonance (EPR) and optically detected magnetic resonance (ODMR) were performed on undoped (highly resistive and n-type) and intentionally doped (Si,

E. R Glaser; W. E Carlos; G. C. B Braga; J. A Freitas; W. J Moore; B. V Shanabrook; A. E Wickenden; D. D Koleske; R. L Henry; M. W Bayerl; M. S Brandt; H Obloh; P Kozodoy; S. P DenBaars; U. K Mishra; S Nakamura; E Haus; J. S Speck; J. E Van Nostrand; M. A Sanchez; E Calleja; A. J Ptak; T. H Myers; R. J Molnar

2002-01-01

366

Biochemical sensors based on polymer microrings with sharp asymmetrical resonance  

NASA Astrophysics Data System (ADS)

Photonic microresonators have great potential in the application of highly sensitive sensors due to high Q-factor resonances and steep slopes between zero and unity transmission. A microring resonator with increased resonance slopes is proposed by introducing two partially reflecting elements implemented by waveguide offsets. This configuration produces a Fano-resonant line shape and can greatly enhance the sensitivity of the sensor. Polystyrene microring resonators were fabricated by the nanoimprinting technique, and the optical spectra were measured in glucose solutions of different concentrations. The shift in resonant wavelength and variation of the normalized transmitted intensity are linearly related to the concentration of the glucose solution.

Chao, Chung-Yen; Guo, L. Jay

2003-08-01

367

Optically detected magnetic resonance (ODMR) of photoexcited triplet states  

Microsoft Academic Search

Optically Detected Magnetic Resonance (ODMR) is a double resonance technique which combines optical measurements (fluorescence,\\u000a phosphorescence, absorption) with electron spin resonance spectroscopy. After the first triplet-state ODMR experiments in\\u000a zero magnetic field reported in 1968 by Schmidt and van der Waals, the number of double resonance studies on excited triplet\\u000a states grew rapidly. Photosynthesis has proven to be a fruitful

Donatella Carbonera

2009-01-01

368

Resonance Control for a CW (Continuous Wave) Accelerator.  

National Technical Information Service (NTIS)

A resonance-control technique is described that has been successfully applied to several cw accelerating structures built by the Los Alamos National Laboratory for the National Bureau of Standards and for the University of Illinois. The technique involves...

L. M. Young R. S. Biddle

1987-01-01

369

NQR-NMR studies of higher alcohol synthesis Cu-Co catalysts. Quarterly technical progress report, June 15--September 15, 1991  

SciTech Connect

Our previous studies (1,2) on the zerofield NMR spectra of Cu/Co catalysts revealed that the method of preparation sensitively influences the magnetic character of the Catalyst. Catalytic studies of the earlier investigators also (3) show similar influence on the product selectivity and indicate reproducible performance is critically dependent on the control and rigor of the preparation technique. To compliment the NMR results, we have made a thorough investigation of the Hysteresis character of the Cu/Co catalysts with the metal ratio varying from 0.2 to 4.0.

Not Available

1991-12-17

370

Nuclear Resonance Fluorescence of 237 Np  

SciTech Connect

Identification and characterization of fissile material is of international concern because of the possibility of proliferation. For safeguards applications, techniques providing isotopic information are necessary [1]. However, few techniques can distinguish between fissile isotopes. Nuclear resonance fluorescence is one technique that can be used in applications to identify and quantify isotopic content. NRF has also been proposed in several detector systems as a viable way to identify fissile material in cargo containers [2, 3]. It is necessary to measure the characteristic resonances of each isotope that is to be distinguished in identification and assay applications.

Angell, Chris T.; Yee, R.; Joshi, T.; Swanberg, E.; Norman, E. B.; Hicks, C. L.; Klimenko, A.; Korbly, Steve; Wilson, C.; Kulp, W. D.; Warren, Glen A.; Bray, T. H.; Copping, R.; Glans, P.A.; Tyliszczak, T.; Shuh, David K.

2010-11-15

371

Luminescence resonance energy transfer  

SciTech Connect

Fluorescence resonance energy transfer (FRET), in which a fluorescent donor molecule transfers energy via a nonradiative dipole-dipole interaction to an acceptor molecule (which is usually a fluorescent molecule), is a standard spectroscopic technique for measuring distances in the 10-70 Angstrom range. We have used a luminescent europium chelate as donor and an organic dye, CY-5, as acceptor. This luminescence resonance energy transfer (LRET) has several advantages over the more conventional FRET. The distance at which 50% of the energy is transferred (R[sub 0]) is large, 70 [angstrom]; the donor lifetime is single exponential and long (0.63 ms in H[sub 2]O; 2.5 ms in D[sub 2]O), making lifetime measurements facile and highly accurate; the orientation dependence (k[sup 2]) of energy transfer is minimized by the donor's multiple electronic transitions and long lifetime, limiting uncertainty in the measured distance due to orientation effects to [+-]12% in the worst case; the sensitized emission of the acceptor can be measured with little or no interfering background, yielding a >50-fold improvement in signal to background over standard donor-acceptor pairs and enabling distances several times R[sub 0] to be measured. 13 refs., 4 figs.

Selvin, P.R.; Rana, T.M.; Hearst, J.E. (Univ. of California, Berkeley, CA (United States) Lawrence Berkeley Lab., CA (United States))

1994-06-29

372

Carbon nanotube mechanical resonators  

NASA Astrophysics Data System (ADS)

Nano-electromechanical systems (NEMS) make use of electrically induced mechanical motion and vice versa. Carbon nanotubes are ideal building blocks of NEMS because of their unique (mechanical) properties and their low mass. This puts them in an unexplored regime of motion which approaches the fundamental detection limit set by quantum mechanics. At room temperature, we use mixing techniques to probe the bending-mode vibration of a suspended carbon nanotube; the gate voltage strains the carbon nanotube and thereby tunes the frequency. At low temperatures, mechanical vibrations are actuated by a nearby antenna and a record high Q-value of 150000 at a resonance frequency of 300 MHz is achieved. Electron tunneling and mechanical motion are strongly coupled resulting in single- electron tuning oscillations of the mechanical frequency and in energy transfer to the electrons causing mechanical damping. Strikingly, we also observe that a d.c. current through the nanotube spontaneously drives the mechanical resonator, exerting a force that is synchronized with the high-frequency vibrations.

van der Zant, Herre

2010-03-01

373

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

374

Multifrequency spin resonance in diamond  

NASA Astrophysics Data System (ADS)

Magnetic resonance techniques provide a powerful tool for controlling spin systems, with applications ranging from quantum information processing to medical imaging. Nevertheless, the behavior of a spin system under strong excitation remains a rich dynamical problem. In this paper, we examine spin resonance of the nitrogen-vacancy center in diamond under conditions outside the regime where the usual rotating-wave approximation applies, focusing on effects of multifrequency excitation and excitation with orientation parallel to the spin quantization axis. Strong-field phenomena such as multiphoton transitions and coherent destruction of tunneling are observed in the spectra and analyzed via numerical and analytic theory. In addition to illustrating the response of a spin system to strong multifrequency excitation, these observations may inform techniques for manipulating electron-nuclear spin quantum registers.

Childress, Lilian; McIntyre, Jean

2010-09-01

375

Modeling of the Electrostatic (Plasmon) Resonances in Metallic and Semiconductor Nanoparticles  

Microsoft Academic Search

Plasmon (electrostatic) resonances are treated as an eigenvalue problem for specific boundary integral equation. This leads to direct calculation of resonance values of permittivity and resonance frequency. The technique is illustrated by numerical examples of calculation of resonance frequencies for 3D nanoparticles.

Isaak D. Mayergoyz; Zhenyu Zhang

2005-01-01

376

Resonance Raman studies of metalloporphyrins  

Microsoft Academic Search

The biological and chemical importance of metalloporphyrins has stimulated extensive studies on the physicochemical properties\\u000a of the macrocycle during recent years. Because of their strong absorption in the visible and near-UV region and the availability\\u000a of tunable lasers, resonance Raman scattering from metalloporphyrins has emerged as a very sensitive and selective technique\\u000a for probing structural details and nature of bonding

A. L. Verma; G. S. S. Saini; N. K. Chaudhury

1992-01-01

377

Electron-nuclear double resonance.  

PubMed

The application of electron-nuclear double resonance (ENDOR) spectroscopy for the investigation of photosynthetic systems is reviewed. The basic principles of continuous wave and pulse ENDOR are presented. Selected examples of the application of the ENDOR technique for studying stable and transient paramagnetic species, including cofactor radical ions, radical pairs, triplet states, and the oxygen-evolving complex in plant Photosystem II (PSII) are discussed. Limitations and perspectives of ENDOR spectroscopy are outlined. PMID:19184518

Kulik, Leonid; Lubitz, Wolfgang

378

Hadronic Resonances from Lattice QCD  

SciTech Connect

The determination of the pattern of hadronic resonances as predicted by Quantum Chromodynamics requires the use of non-perturbative techniques. Lattice QCD has emerged as the dominant tool for such calculations, and has produced many QCD predictions which can be directly compared to experiment. The concepts underlying lattice QCD are outlined, methods for calculating excited states are discussed, and results from an exploratory Nucleon and Delta baryon spectrum study are presented.

John Bulava; Robert Edwards; George Fleming; K. Jimmy Juge; Adam C. Lichtl; Nilmani Mathur; Colin Morningstar; David Richards; Stephen J. Wallace

2007-06-16

379

Doubly rotated contoured quartz resonators  

Microsoft Academic Search

Doubly rotated contoured quartz resonators are used in the design of temperature-compensated stable clocks and dual-mode sensors for simultaneous measurements of pressure and temperature. The design of these devices is facilitated by models that can predict frequency spectra associated with the three thickness modes and temperature and stress-induced frequency changes as a function of crystalline orientation. The Stevens-Tiersten technique for

Bikash K. Sinha

2001-01-01

380

Ferrite-filled cavity resonators  

Microsoft Academic Search

An approximation technique is developed for the electromagnetic resonances and electric fields inside a cavity of arbitrary\\u000a shape whose walls are perfectly conducting and which is filled with a lossless ferrite. Operator notation is introduced and\\u000a it is proved that the operator for this problem is self-adjoint. A variational expression is introduced and this functional\\u000a is minimized by employing the

D. A. Taggart; F. W. Schott

1972-01-01

381

Hadronic Resonances from Lattice QCD  

SciTech Connect

The determination of the pattern of hadronic resonances as predicted by Quantum Chromodynamics requires the use of non-perturbative techniques. Lattice QCD has emerged as the dominant tool for such calculations, and has produced many QCD predictions which can be directly compared to experiment. The concepts underlying lattice QCD are outlined, methods for calculating excited states are discussed, and results from an exploratory Nucleon and Delta baryon spectrum study are presented.

Lichtl, Adam C. [RBRC, Brookhaven National Laboratory, Upton, NY 11973 (United States); Bulava, John; Morningstar, Colin [Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Edwards, Robert; Mathur, Nilmani; Richards, David [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Fleming, George [Yale University, New Haven, CT 06520 (United States); Juge, K. Jimmy [Department of Physics, University of the Pacific, Stockton, CA 95211 (United States); Wallace, Stephen J. [University of Maryland, College Park, MD 20742 (United States)

2007-10-26

382

Gallium nitride nanowire electromechanical resonators  

NASA Astrophysics Data System (ADS)

Nanoscale mechanical resonators are of great interest for high-resolution sensing applications, where the small resonator mass and high quality factor (Q, defined as resonance frequency f0 over full width at half maximum power) lead to unprecedented sensitivity. Here, we investigate gallium nitride (GaN) nanowire (NW) resonators. The single-crystal, c-axis NWs are 5 mum -- 20 mum long, with diameters from 50 nm -- 500 nm, and grow essentially free of defects. Our initial experiments involve measuring the resonances of as-grown NWs in a scanning electron microscope, where we observe exceptionally high Q values of 10 4 -- 105, one to two orders of magnitude higher than most NWs of comparable size. Using a single NW as a mass sensor, we then demonstrate a sub-attogram mass sensitivity. To provide a more flexible measurement technique that avoids electron-microscope detection, we fabricate doubly clamped NWs with an entirely electronic drive and readout scheme using a combination of lithographic patterning and dielectrophoresis. An electrostatic gate induces vibration, while readout utilizes the piezoresistivity of GaN. Observed resonances range from 9--36 MHz with Q values typically around 103 at room temperature and 10 -4 Pa. We use the behavior of f0 and Q to sense the NW's local environment, such as the additional sources of energy dissipation not present in the as-grown NWs. By cooling the device to 8 K, Q increases by an order of magnitude to above 104, with a highest value to date of 26,000 under vacuum. We explore additional NW properties through the thermal noise in the NW's mechanical motion and the exponential decay of mechanical motion in the presence of burst drive. Finally, we investigate the low-frequency 1/f parameter noise displayed by f0. We show that the noise in f0 is consistent with noise in the NW's resistance leading to temperature noise from local Joule heating, which in turn generates resonance frequency noise. For sensor applications, there will be optimal drive conditions that balance the f 0 noise with the signal-to-noise ratio of the system. With these insights, along with the simple drive and readout technique, these GaN-NW doubly clamped resonators have significant potential for high-resolution sensing applications.

Gray, Jason Michael

383

Magnetic resonance of a single molecular spin  

NASA Astrophysics Data System (ADS)

THE introduction of optical detection methods for observing magnetic resonance transitions in metastable paramagnetic states1-4 has contributed enormously to our understanding of the properties of photoexcited molecules in condensed phases. In such experiments the luminescence intensity is recorded as a function of the frequency of an applied microwave field. At resonance with transitions between sublevels of a metastable paramagnetic state, the lifetime of the metastable state is altered and a consequent change in the luminescence intensity is observed. Here we report the observation of such optically detected magnetic resonance transitions for the triplet state of a single pentacene molecule embedded in a p-terphenyl host crystal. This result has been obtained by combining the conventional optical detection technique for observing magnetic resonance transitions1-4 with the new single-molecule optical detection methods developed recently5,6. This observation opens the way for magnetic resonance studies in condensed phases with single-molecule sensitivity.

Khler, J.; Disselhorst, J. A. J. M.; Donckers, M. C. J. M.; Groenen, E. J. J.; Schmidt, J.; Moerner, W. E.

1993-05-01

384

Optical Detection and Excitation of Vibrations in Silicon Resonator Sensors.  

NASA Astrophysics Data System (ADS)

Available from UMI in association with The British Library. The principle aim of this work was to investigate optical techniques for the excitation and detection of vibrations, at resonance, in Silicon resonator sensors. Two all-fibre detection techniques have been developed: one is based on phase modulation and the other on intensity modulation of the optical wave train. Both detection techniques may be implemented in either single mode or multimode fibre. The choice of measurement technique is determined by the desired system performance and cost. The development of these detection systems naturally led to a study of the properties of the sensors, and the characteristics of a pressure transducer and an accelerometer were investigated; the latter is reported in more detail here. The main characteristics studied were modes of resonance, quality factors, resonant frequency shift with temperature, resonant frequency shift with the measurand and the non -linearity of the resonator. Optical excitation of vibrations at resonance was achieved by using a pulsed laser source directly incident on the resonator. The addition of a thin Chrome layer to the resonator improved the largest optically excited amplitude of vibration by a factor of 9 compared with the uncoated resonator.

Tudor, Michael John

1988-12-01

385

[Magnetic resonance imaging elbow anatomy].  

PubMed

Knowledge of the anatomy of the elbow joint has become intricate due to the advent of magnetic resonance imaging (MRI) techniques, as they are superior to represent the different soft tissues. This advantage allows evaluating in detail the increasingly frequent pathologic processes that occur in high performance athletes. The ideal MRI technique includes having the patient in a comfortable position, using an appropriate surface antenna and the right sequences in the appropriate planes depending on the entity. Being familiar with the normal elbow anatomy is crucial to properly identify the pathology and avoid potential diagnostic errors. PMID:22509650

Rodrguez-Ramrez, C L; Aguila-Mendoza, A

386

Electron spin resonance (ESR), electron nuclear double resonance (ENDOR) and general triple resonance of irradiated biocarbonates  

Microsoft Academic Search

Several irradiated biocarbonates were studied by magnetic resonance techniques. Seven paramagnetic species, attributed to CO2?, SO2? and SO3? were identified. Comparison between radiation induced defects in bioaragonites and aragonite single-crystals shows that isotropic and orhorhombic CO2? centers with broad line spectra are not produced in the latter samples. Vibrational and rotational properties of isotropic CO2? centers were studied from low

D. U. Schramm; A. M. Rossi

1996-01-01

387

Isomer-shift analogue in neutron resonances  

Microsoft Academic Search

For the first time, the recently predicted chemical shift of neutron resonances, to be regarded as an analogue to the Mssbauer isomer shift, has been experimentally observed studying the 6.67 eV resonance of 238U. The experimental shifts were determined by a chi-square fitting technique from the time-of-flight transmission spectra of metallic uranium and four uranium compounds measured at the Dubna

A. Meister; D. Pabst; L. B. Pikelner; K. Seidel

1981-01-01

388

Composite resonator vertical cavity laser diode  

SciTech Connect

The use of two coupled laser cavities has been employed in edge emitting semiconductor lasers for mode suppression and frequency stabilization. The incorporation of coupled resonators within a vertical cavity laser opens up new possibilities due to the unique ability to tailor the interaction between the cavities. Composite resonators can be utilized to control spectral and temporal properties within the laser; previous studies of coupled cavity vertical cavity lasers have employed photopumped structures. The authors report the first composite resonator vertical cavity laser diode consisting of two optical cavities and three monolithic distributed Bragg reflectors. Cavity coupling effects and two techniques for external modulation of the laser are described.

Choquette, K.D.; Hou, H.Q.; Chow, W.W.; Geib, K.M.; Hammons, B.E.

1998-05-01

389

Quasi-resonant converters - Topologies and characteristics  

NASA Astrophysics Data System (ADS)

In designing switching dc-dc converters, the effort to increase operating frequency to reduce weight, size, and cost of magnetic and filter elements is constantly hampered by higher switching stresses and switching losses. To overcome these obstacles, the concept of the 'resonant switch' is proposed. By incorporating additional inductor and capacitor elements to shape the semiconductor switch's current waveform, a 'zero-current switching' property can be realized. Based on the resonant switch technique, a new host of quasi-resonant converter circuits have been derived, which can be operated in the megahertz range.

Liu, Kwang-Hwa; Oruganti, Ramesh; Lee, Fred C. Y.

1987-01-01

390

ELM mitigation techniques  

NASA Astrophysics Data System (ADS)

Large edge-localized mode (ELM) control techniques must be developed to help ensure the success of burning and ignited fusion plasma devices such as tokamaks and stellarators. In full performance ITER tokamak discharges, with QDT = 10, the energy released by a single ELM could reach 30 MJ which is expected to result in an energy density of 10-15 MJ/m2on the divertor targets. This will exceed the estimated divertor ablation limit by a factor of 20-30. A worldwide research program is underway to develop various types of ELM control techniques in preparation for ITER H-mode plasma operations. An overview of the ELM control techniques currently being developed is discussed along with the requirements for applying these techniques to plasmas in ITER. Particular emphasis is given to the primary approaches, pellet pacing and resonant magnetic perturbation fields, currently being considered for ITER.

Evans, T. E.

2013-07-01

391

Mutual Orientations of the Principal Axes of the Electric-Field Gradient Tensors on 14N and 81Br by Combined Zeeman-Effect Measurements in a Single Crystal of p-Bromoaniline  

Microsoft Academic Search

The Zeeman effect of the nuclear quadrupole resonance of both 14N and 81Br nuclei in a single crystal of p-bromoaniline was studied. The precision of the technique used here is far greater than that of the few previous works in this field. Measurements were made by means of a newly designed spectrometer, working at both 14N and 81Br NQR frequencies,

A. Colligiani; R. Ambrosetti; P. Cecchi

1971-01-01

392

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

393

Some Reflections Concerning Magnetic Resonance Phenomena in the Domain of Radio Frequencies.  

National Technical Information Service (NTIS)

Several suggestions are advanced concerning the development and use of methods of radio-electric resonance. Initial attention is focused on the study of photomagnetic effects by magnetic resonance techniques. It is demonstrated that the existence of a spi...

A. Kastler

1973-01-01

394

Investigation of Non-Linear Estimation of Natural Resonances in Target Identification.  

National Technical Information Service (NTIS)

This investigation considers a non-linear technique for extracting natural resonances from transient electromagnetic scattering responses of radar targets. These natural resonances represent the complex poles of the target's transfer function in the Lapla...

C. Y. Chong

1983-01-01

395

Versatile Magnetic Resonance Spectrometer  

Microsoft Academic Search

A Pound-Knight-Watkins marginal oscillator has been modified by the addition of a vibrating capacitor in parallel with the tuning capacitor to produce a simple circuit which may be used to observe paramagnetic resonance at low fields, nuclear magnetic resonance, and nuclear quadrupole resonance. Suggestions are made as to the type of information which may be obtained in an undergraduate laboratory

J. A. Cowen; W. H. Tanttila

1958-01-01

396

VERSATILE MAGNETIC RESONANCE SPECTROMETER  

Microsoft Academic Search

A Pound-Knight-Watkins marginal osciliator was modified by the addition ; of a vibrating capacitor in parallel with the tuning capacitor to produce a ; simple circuit which may be used to observe paramagnetic resonance at low fields, ; nuclear magnetic resonance, and nuclear quadrupole resonance. Suggestions are ; mnde as to the type of information which may be obtained in

J. A. Cowen; W. H. Tanttila

1958-01-01

397

Nuclear magnetic resonance spectroscopy  

Microsoft Academic Search

Magnetic resonance spectroscopy is a valuable method for the non-invasive investigation of metabolic processes and can now be combined with conventional magnetic resonance imaging in patients. This article gives a brief introduction into the principles and physiological and clinical applications of in vivo proton magnetic resonance spectroscopy, surveys experiences in healthy volunteers and presents exemplary results in patients suffering from

Armin Ettl; Christa Fischer-Klein; Andreas Chemelli; Albert Daxer; Stephan Felber

1994-01-01

398

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

399

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

400

Fabrication of Ta2O5/GeNx gate insulator stack for Ge metal-insulator-semiconductor structures by electron-cyclotron-resonance plasma nitridation and sputtering deposition techniques  

NASA Astrophysics Data System (ADS)

The authors have fabricated germanium (Ge) metal-insulator-semiconductor (MIS) structures with a 7-nm-thick tantalum pentaoxide (Ta2O5)/2-nm-thick germanium nitride (GeNx) gate insulator stack by electron-cyclotron-resonance plasma nitridation and sputtering deposition. They found that pure GeNx ultrathin layers can be formed by the direct plasma nitridation of the Ge surface without substrate heating. X-ray photoelectron spectroscopy revealed no oxidation of the GeNx layer after the Ta2O5 sputtering deposition. The fabricated MIS capacitor with a capacitance equivalent thickness of 4.3 nm showed excellent leakage current characteristics. The interface trap density obtained by the modified conductance method was 41011 cm-2 eV-1 at the midgap.

Otani, Yohei; Itayama, Yasuhiro; Tanaka, Takuo; Fukuda, Yukio; Toyota, Hiroshi; Ono, Toshiro; Mitsui, Minoru; Nakagawa, Kiyokazu

2007-04-01

401

Diffusion-weighted magnetic resonance imaging.  

PubMed

Diffusion-weighted magnetic resonance imaging is a specialized technique that measures the degree of diffusion of water molecules within extracellular space and between intracellular and extracellular space. Diffusion-weighted imaging signal is high (bright) when diffusion is restricted, as occurs in cytotoxic damage from ischemia, inflammation, trauma, or tumor. This technique, now available on most magnetic resonance imaging units, is especially helpful in detecting early ischemic stroke and multiple sclerosis and in differentiating arachnoid cyst from epidermoid tumor and brain abscess from neoplasm. PMID:12131474

Mukherji, Suresh K; Chenevert, Thomas L; Castillo, Mauricio

2002-06-01

402

Resonance ionization spectroscopy 1994. Seventh International Symposium  

SciTech Connect

These proceedings present papers presented at the Seventh International Symposium on resonance ionization spectroscopy and its applications. The meeting was held in Bernkastel-Kues, Germany. topics for the program include ultrasensitive techniques, femtosecond resonance ionization spectroscopy RIS and biological applications, RIS for atomic physics and surface analysis, RIS for molecular physics, new laser sources and applications, RIS applied to nuclear and particle physics, geophysics, analytical and environmental applications and new techniques and application. There were 112 papers presented at the symposium, out of these 17 have been abstracted for the Energy Science and Technology database. (AIP)

Kluge, H.-J.; Wendt, K. [eds.] [Institut fur Physik, Universitat Mainz, D-55029 Mainz (Germany); Parks, J.E. [ed.] [The University of Tennessee (United States)

1995-12-31

403

Resonance asymmetry phenomenon in waveguide-type optical ring resonator gyro  

NASA Astrophysics Data System (ADS)

The intensity output of a silica waveguide ring resonator (WRR) was found to show an asymmetric resonance characteristic. To further analyze and better design the resonator micro optic gyro (RMOG) with a waveguide-type ring resonator, in-depth research of the characteristics of the resonance asymmetry is fully developed for the first time, to the best of our knowledge. Four possible sources of the resonance asymmetry are analyzed and their respective contributions are compared. These four error sources are differential normal mode losses in the coupler, the backscattering induced noises, the polarization fluctuations and the optical Kerr effect. The differential normal mode loss is suspected to be the major contributor to the observed resonance asymmetry in the fabricated silica WRR. Asymmetric resonance curve produces a large output bias error in the RMOG based on the phase modulation technique, which is related to the modulation frequency differences between the CW and CCW lightwaves. Theoretical analysis shows that replacing the reflector WRR with a transmitter one is helpful to eliminate the effect of the different normal mode losses in the coupler on the resonance asymmetry.

Chang, Xu; Ma, Huilian; Jin, Zhonghe

2012-03-01

404

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

405

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

406

Coherent excitation of autoionizing resonances  

SciTech Connect

An electron-electron coincidence [or (e,2e)] technique was used to investigate atomic ionization by electron impact in the neighborhood of autoionizing resonances. Differing binary (I{sup +}) and recoil (I{sup -}) lobe intensities in coplanar (e,2e) ejected-electron angular distributions were analyzed in terms of interference cross-terms, between opposite parity final-state continua, that change sign when {theta}{sub ej} {yields} {theta}{sub ej} + 180{sup o} in the angular distributions. The magnitude of these cross-terms varies rapidly with ejected-electron energy across overlapping autoionizing resonances. The energy variation in the interference terms may be examined by obtaining the sum (I{sup +} + I{sup -}) and difference (I{sup +} - I{sup -}) of (e,2e) energy spectra measured at ejected-electron angles 180{sup o} apart.

Martin, N.L.S.

2002-10-03

407

Magnetic Resonance Reporter Gene Imaging  

PubMed Central

Molecular imaging has undergone an explosive advancement in recent years, due to the tremendous research efforts made to understand and visualize biological processes. Molecular imaging by definition assesses cellular and molecular processes in living subjects, with the targets of following metabolic, genomic, and proteomic events. Furthermore, reporter gene imaging plays a central role in this field. Many different approaches have been used to visualize genetic events in living subjects, such as, optical, radionuclide, and magnetic resonance imaging. Compared with the other techniques, magnetic resonance (MR)-based reporter gene imaging has not occupied center stage, despite its superior three-dimensional depictions of anatomical details. In this article, the authors review the principles and applications of various types of MR reporter gene imaging technologies and discuss their advantages and disadvantages.

Lee, Sheen-Woo; Lee, Sang-Hoon; Biswal, Sandip

2012-01-01

408

Experimental investigation of flow-induced cavity resonance  

NASA Astrophysics Data System (ADS)

The resonant excitation of a cavity by an equilibrium turbulent grazing flow was investigated. The mechanism causing the excitation arises from discrete vortices shed periodically from the upstream edge of the cavity opening. The shedding is controlled by feedback from the flow field near the downstream edge. The objectives of the research were first, to understand the dynamic processes related to the sheartones generated by the vortex shedding, and then to determine practical techniques for controlling the excitation and reducing the resonance. Detailed measurements of the cavity pressure and the velocity field in the opening were performed in a quiet flow facility. Spectral data on cavity pressure fluctuations obtained for a variety of configurations were analyzed over a range of speeds to determine the behavior of both sheartones and cavity tones during non resonant and resonant conditions. The mean and fluctuating velocity profiles as well as the cross- spectral properties between the velocity components and cavity pressure were also obtained within the cavity opening. The coherence identified the coupling while the phase was used to calculate the streamwise convection velocities across the opening. The data support the finding that the resonant and non-resonant conditions are distinguished by the behavior of the convection velocity and by the distribution of energy production in the flow field. Techniques for controlling cavity resonance were also investigated. The measurements and data analyses techniques discussed above were also performed for three practical devices. These include a fence upstream of the leading edge, air injection near the leading edge, and a technique, developed by the author, whereby fluid is diverted into the cavity from the boundary layer. The fence and the diversion technique lower the Strouhal number of the sheartones so that resonance occurs at a higher speed. All techniques lower the resonance level. The diversion technique is the most effective in reducing cavity resonance.

Zoccola, Paul Joseph, Jr.

2000-10-01

409

Hadronic resonances at ALICE  

NASA Astrophysics Data System (ADS)

Measurements of the ratios of hadronic resonance yields to non-resonance yields can be used to study the properties of the hadronic phase of high-energy heavy-ion collisions. A change in resonance masses or widths could be an indication of chiral symmetry restoration. Measurements of resonances in proton-proton collisions provide an important baseline for measurements in heavy-ion collisions as well as data for tuning QCD-inspired particle production models. The ALICE collaboration has measured the K*(892)0 and phi(1020) resonances in Pb-Pb collisions at = 2.76 TeV and the K*(892)0, phi(1020), and ?*(1385) resonances in pp collisions at = 7 TeV. These measurements - including transverse momentum spectra, ratios to non-resonances, masses, and widths - are discussed and compared to theoretical predictions.

Knospe, A. G.; Alice Collaboration

2013-09-01

410

Role of chelates in magnetic resonance imaging studies.  

PubMed

Imaging studies are tests performed with a variety of techniques that produce pictures of the inside of a patient's body. Magnetic resonance imaging (MRI) is an imaging technique based on the principles of nuclear magnetic resonance. MRI uses a powerful magnetic field, radio waves, and a computer to produce detailed pictures of organs, soft tissues, bone, and virtually all other internal body structures. Chelates have a wide application in such imaging techniques. Chelates in imaging studies are used alone as radioactive agents or conjugated to monoclonal antibodies or to DNA as radioactive agents. Technetium chelates and gadolinium chelates are being widely used as magnetic resonance contrast media. PMID:19841554

Tripathi, Laxmi; Kumar, Praveen; Singh, Ranjit

411

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

412

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

413

Resonant phenomena in conductor-backed coplanar waveguides (CBCPW's)  

Microsoft Academic Search

A thorough and systematic investigation of resonant phenomena in conductor-backed coplanar waveguides (CBCPWs) is reported. A rigorous three dimensional full-wave space-domain integral equation method accompanied by an S-parameter extraction technique is used. A series of measurements has been conducted to confirm the theoretical results. A patch-resonator model and a microstriplike (MSL) model are employed to understand the origin of resonance

Wen-Teng Lo; C.-K. C. Tzuang; S.-T. Peng; Ching-Cheng Tien; Chung-Chi Chang; Jenq-Wen Huang

1993-01-01

414

Detecting response of microelectromechanical resonators by microwave reflectometry  

NASA Astrophysics Data System (ADS)

Microwave reflectometry is proposed as an effective technique to detect the vibration of capacitively transduced microelectromechanical resonators. The transducer capacitor is probed by an incident wave, which is reflected being modulated by the time variations of the resonator displacement. Calculations demonstrate that the sensitivity of the technique is maximum for a given microwave frequency depending on the transducer total capacitance. Experimental data show that capacitance variations as low as 3 zF/?Hz are measurable at 4 GHz for the studied devices. Such a performance corresponds to a sub-picometer resolution in vibration amplitude of the microelectromechanical resonator. The measurement technique is particularly appropriate for resonant sensors when high signal-to-noise ratio and fully electrical detection are required. It can be used for device resonance frequency up to several hundreds of MHz.

Legrand, B.; Ducatteau, D.; Thron, D.; Walter, B.; Tanbakuchi, H.

2013-07-01

415

Diagnostic cardiology: Noninvasive imaging techniques  

SciTech Connect

This book contains 23 chapters. Some of the chapter titles are: The chest x-ray and cardiac series; Computed tomographic scanning of the heart, coronary arteries, and great vessels; Digital subtraction angiography in the assessment of cardiovascular disease; Magnetic resonance: technique and cardiac applications; Basics of radiation physics and instrumentation; and Nuclear imaging: the assessment of cardiac performance.

Come, P.C.

1985-01-01

416

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

417

A Novel Method of Combining Blood Oxygenation and Blood Flow Sensitive Magnetic Resonance Imaging Techniques to Measure the Cerebral Blood Flow and Oxygen Metabolism Responses to an Unknown Neural Stimulus  

PubMed Central

Simultaneous implementation of magnetic resonance imaging methods for Arterial Spin Labeling (ASL) and Blood Oxygenation Level Dependent (BOLD) imaging makes it possible to quantitatively measure the changes in cerebral blood flow (CBF) and cerebral oxygen metabolism (CMRO2) that occur in response to neural stimuli. To date, however, the range of neural stimuli amenable to quantitative analysis is limited to those that may be presented in a simple block or event related design such that measurements may be repeated and averaged to improve precision. Here we examined the feasibility of using the relationship between cerebral blood flow and the BOLD signal to improve dynamic estimates of blood flow fluctuations as well as to estimate metabolic-hemodynamic coupling under conditions where a stimulus pattern is unknown. We found that by combining the information contained in simultaneously acquired BOLD and ASL signals through a method we term BOLD Constrained Perfusion (BCP) estimation, we could significantly improve the precision of our estimates of the hemodynamic response to a visual stimulus and, under the conditions of a calibrated BOLD experiment, accurately determine the ratio of the oxygen metabolic response to the hemodynamic response. Importantly we were able to accomplish this without utilizing a priori knowledge of the temporal nature of the neural stimulus, suggesting that BOLD Constrained Perfusion estimation may make it feasible to quantitatively study the cerebral metabolic and hemodynamic responses to more natural stimuli that cannot be easily repeated or averaged.

Simon, Aaron B.; Griffeth, Valerie E. M.; Wong, Eric C.; Buxton, Richard B.

2013-01-01

418

Piezoelectric-Crystal-Resonator High-Frequency Gravitational Wave Generation and Synchro-Resonance Detection  

Microsoft Academic Search

Here we show the generation of high-frequency-gravitational-waves (HFGWs) utilizing piezoelectric elements such as the ubiquitous Film-Bulk-Acoustic-Resonators (FBARs), found in cell phones, as energized by inexpensive magnetrons, found in microwave ovens, generating GWs having a frequency of about 4.9GHz and their detection by means of new synchro-resonance techniques developed in China. In the 1960s Weber suggested piezoelectric crystals for gravitational-wave (GW)

Robert M. L. Baker; R. Clive Woods; Fangyu Li

2006-01-01

419

Resonant-cantilever bio\\/chemical sensors with an integrated heater for both resonance exciting optimization and sensing repeatability enhancement  

Microsoft Academic Search

With an integrated resonance exciting heater and a self-sensing piezoresistor, resonant micro-cantilever bio\\/chemical sensors are optimally designed and fabricated by micromachining techniques. This study is emphasized on the optimization of the integrated heating resistor. Previous research has put the heater at either the cantilever clamp end, the midpoint or the free end. Aiming at sufficiently high and stable resonant amplitude,

Haitao Yu; Xinxin Li; Xiaohua Gan; Yongjing Liu; Xiang Liu; Pengcheng Xu; Jungang Li; Min Liu

2009-01-01

420

Implementation and evaluation of the pulse field gradient technique for the prediction of soluble solids content of fruit juices and soluble solids content and defects in apple tissue using a low frequency proton magnetic resonance sensor  

Microsoft Academic Search

The pulsed field gradient technique (PFG) was implemented in a 5.40 MHz $\\\\sp1$H-MR system. A quadrupole coil was used for applying 10 to 15 G\\/cm gradient pulses. The self-diffusion coefficient of water, $\\\\rm D\\\\sb{w},$ and spin-spin relaxation time, T$\\\\sb2,$ were measured in aqueous solutions of citric acid and\\/or Na-citrate buffer. Soluble solids of the solutions ranged from 0% to 16%.

Kevin Michael Keener

1996-01-01

421

Improved CW Technique for Measurement of Ultrasonic Attenuation.  

National Technical Information Service (NTIS)

A technique is described for measuring ultrasonic attenuation by determining the inflectional points of ultrasonic standing wave resonances. Measurements on tantalum are reported. Results obtained by this technique agree with those obtained by the pulse e...

R. G. Leisure

1972-01-01

422

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

423

Dielectric ring resonators loaded in waveguide and on substrate  

Microsoft Academic Search

A rigorous mode matching technique is used to analyze the dielectric ring resonators loaded in a waveguide and on top of a substrate. Variation of several lowest order modes' resonant frequencies as a function of structure parameters is presented and is shown to be helpful for optimization of spurious mode separation. Two-dimensional electric and magnetic field line patterns and three-dimensional

Seng-Woon Chen; Kawthar A. Zaki

1991-01-01

424

Classification of prostate magnetic resonance spectra using Support Vector Machine  

Microsoft Academic Search

Prostate cancer is the most common cancer in men over 50 years of age and it has been shown that nuclear magnetic resonance spectra are sensitive enough to distinguish normal and cancer tissues. In this paper, we propose a classification technique of spectra from magnetic resonance spectroscopy. We studied automatic classification with and without quantification of metabolite signals. The dataset

S. Parfait; P. M. Walker; G. Crhange; X. Tizon; J. Mitran

425

Magnetic response of nanostructured systems: A ferromagnetic resonance investigation  

Microsoft Academic Search

Ferromagnetic resonance (FMR) measurements probe the response of magnetic systems within the nanosecond-regime due to an excitation within the microwave regime. Due to the high sensitivity of FMR this technique is well suited for the investigation of nanostructures and ultrathin magnetic films or multilayers. As the resonance condition is determined by internal fields like anisotropy fields or interlayer coupling fields

J. Lindner; U. Wiedwald; K. Baberschke; M. Farle

2005-01-01

426

Maximum Entropy Reconstruction Methods in Electron Paramagnetic Resonance Imaging  

Microsoft Academic Search

Electron Paramagnetic Resonance (EPR) is a spectroscopic technique that detects and characterizes molecules with unpaired electrons (i.e., free radicals). Unlike the closely related nuclear magnetic resonance (NMR) spectroscopy, EPR is still under development as an imaging modality. Athough a number of physical factors have hindered its development, EPR's potential is quite promising in a number of important application areas, including

Calvin A. Johnson; Delia Mcgarry; John A. Cook; Nallathamby Devasahayam; James B. Mitchell; Sankaran Subramanian; Murali C. Krishna

2003-01-01

427

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

428

I Situ Investigation of Linear Viscoelastic Media Using Piezoelectric Resonators  

Microsoft Academic Search

Our effort has been directed towards developing an in-situ technique, the piezoelectric quartz crystal microbalance (QCM), as a probe for viscoelastic fluid property investigation. Specifically, this effort was undertaken to study the effect of liquid elasticity on the response of liquid-contacted quartz crystal resonators. We have modelled the signal response of an externally damped piezoelectric resonator by two different but

Chukuemeka Obioma Nwankwo

1996-01-01

429

Supine magnetic resonance (MR) mammography in radiotherapy planning  

Microsoft Academic Search

Purpose: Radiotherapy of the breast is normally performed in a supine position, so conventional prone magnetic resonance (MR) mammography is unsuitable for radiotherapy planning purposes. No dedicated supine breast coil is yet available, limiting the application of magnetic resonance imaging (MRI) in this area. A technique has been developed on a 0.2T open scanner to produce breast images suitable for

Sadie Dunne; Amanda Gee

1999-01-01

430

Secondary-side resonance for high-frequency power conversion  

NASA Astrophysics Data System (ADS)

A systematic approach is proposed that enables the use of the leakage inductance of the power transformer and a secondary-side capacitor to form a resonant tank for very high frequency power conversion. Several new quasi-resonant converter topologies based on this technique are derived.

Liu, Kwang-Hwa; Lee, Fred C.

431

A personal computer-based nuclear magnetic resonance spectrometer  

Microsoft Academic Search

Nuclear magnetic resonance (NMR) spectroscopy using personal computer-based hardware has the potential of enabling the application of NMR methods to fields where conventional state of the art equipment is either impractical or too costly. With such a strategy for data acquisition and processing, disciplines including civil engineering, agriculture, geology, archaeology, and others have the possibility of utilizing magnetic resonance techniques

Constantin Job; Robert M. Pearson; Michael F. Brown

1994-01-01

432

Determination of Membrane Protein Structure by Rotational Resonance NMR: Bacteriorhodopsin  

Microsoft Academic Search

Rotationally resonant magnetization exchange, a new nuclear magnetic resonance (NMR) technique for measuring internuclear distances between like spins in solids, was used to determine the distance between the C-8 and C-18 carbons of retinal in two model compounds and in the membrane protein bacteriorhodopsin. Magnetization transfer between inequivalent spins with an isotropic shift separation, delta, is driven by magic angle

F. Creuzet; A. McDermott; R. Gebhard; K. van der Hoef; M. B. Spijker-Assink; J. Herzfeld; J. Lugtenburg; M. H. Levitt; R. G. Griffin

1991-01-01

433

The resonant body transistor.  

PubMed

This paper introduces the resonant body transistor (RBT), a silicon-based dielectrically transduced nanoelectromechanical (NEM) resonator embedding a sense transistor directly into the resonator body. Combining the benefits of FET sensing with the frequency scaling capabilities and high quality factors (Q) of internal dielectrically transduced bar resonators, the resonant body transistor achieves >10 GHz frequencies and can be integrated into a standard CMOS process for on-chip clock generation, high-Q microwave circuits, fundamental quantum-state preparation and observation, and high-sensitivity measurements. An 11.7 GHz bulk-mode RBT is demonstrated with a quality factor Q of 1830, marking the highest frequency acoustic resonance measured to date on a silicon wafer. PMID:20180594

Weinstein, Dana; Bhave, Sunil A

2010-04-14

434

Microwave Properties of Vortices in Superconducting Resonators  

NASA Astrophysics Data System (ADS)

Microwave resonators fabricated from superconducting thin films are playing a critical role with recent advances in superconducting quantum computing technology and photon detectors. There has been an intensive worldwide effort to study the sources of loss that limit the quality factors of these resonators. In this thesis, I have focused on the measurements of the microwave response of vortices in Al and Re superconducting thin film resonators cooled in magnetic fields comparable to or less than that of the Earth. Previous work on vortex dynamics at microwave frequencies has involved large magnetic fields, orders of magnitude larger than the Earth's fields. Al and Re are common materials used in superconducting resonant circuits for qubits and detectors. Despite the similarities of Al and Re superconductors, the microwave vortex response is strikingly different in the two materials from my resonator measurements. I present a quantitative model for the dissipation and reactance contributed by the vortices in terms of the elastic pinning forces and the viscous damping from the vortex cores. The differences in the vortex response in Al and Re were due to the vortex pinning strength in the two films. The critical role played by pinning in determining the microwave response motivated us to try to modify the pinning in our Al films by nanostructuring the film surface. A single narrow slot along the center line of a resonator was used to increase the pinning in the resonator traces and resulted in a reduction of the loss from vortices by over an order of magnitude. Such patterned pinning techniques could be used on resonators in systems with insufficient shielding or pulsed control fields to reduce the loss from unwanted trapped vortices. Finally, we explored the possibility for using measurements of the power dependence of the resonators to determine if trapped vortices are present.

Song, Chunhua

435

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

436

Analytical Methods for Characterizing Magnetic Resonance Probes  

PubMed Central

SUMMARY The efficiency of Gd(III) contrast agents in magnetic resonance image enhancement is governed by a set of tunable structural parameters. Understanding and measuring these parameters requires specific analytical techniques. This Feature describes strategies to optimize each of the critical Gd(III) relaxation parameters for molecular imaging applications and the methods employed for their evaluation.

Manus, Lisa M.; Strauch, Renee C.; Hung, Andy H.; Eckermann, Amanda L.; Meade, Thomas J.

2012-01-01

437

Functional Magnetic Resonance Imaging in Nursing Research  

Microsoft Academic Search

Functional magnetic resonance imaging (fMRI) is a powerful noninvasive neuroimaging technique nurse scientists can use to investigate the structure and cognitive capacities of the brain. A strong magnetic field and intermittent high-frequency pulses cause protons in body tissues to release energy, which can be recorded and processed into images that are sensitive to specific tissue characteristics. Although temporal and spatial

L. Clark Johnson; Todd L. Richards; Kristen H. Archbold; Carol A. Landis

2006-01-01

438

Magnetic Resonance Imaging in Biomedical Engineering  

NASA Astrophysics Data System (ADS)

The basic principles of magnetic resonance imaging covering physical principles and basic imaging techniques will be presented as a strong tool in biomedical engineering. Several applications of MRI in biomedical research practiced at the MRI laboratory of the FBMI CTU including other laboratory instruments and activities are introduced.

Ka?par, Jan; Hna, Karel; Smr?ka, Pavel; Brada, Ji?; Bene, Ji?; unka, Pavel

2007-11-01

439

Nuclear magnetic resonance in plant science research  

Microsoft Academic Search

In vivo nuclear magnetic resonance (NMR) spectroscopy and NMR imaging are noninvasive techniques with the potential to investigate a wide range of biochemical and physiological problems in living systems. The extent to which this potential has been realized in plant tissues is discussed with reference to recent applications to a number of systems, including root tissues and plant cell suspensions.

R. G. Ratcliffe

1991-01-01

440

Magnetic Resonance Imaging Methods in Soil Science  

Microsoft Academic Search

Magnetic Resonance Imaging (MRI) is a powerful technique to study water content, dynamics and transport in natural porous media. However, MRI systems and protocols have been developed mainly for medical purposes, i.e. for media with comparably high water contents and long relaxation times. In contrast, natural porous media like soils and rocks are characterized by much lower water contents, typically

A. Pohlmeier; D. van Dusschoten; P. Blmler

2009-01-01

441

Explosives detection with quadrupole resonance analysis  

Microsoft Academic Search

The increase in international terrorist activity over the past decade has necessitated the exploration of new technologies for the detection of plastic explosives. Quadrupole resonance analysis (QRA) has proven effective as a technique for detecting the presence of plastic, sheet, and military explosive compounds in small quantities, and can also be used to identify narcotics such as heroin and cocaine

Timothy J. Rayner; Benjamin D. Thorson; Simon Beevor; Rebecca West; Ronald A. Krauss

1997-01-01

442

Surface spin wave resonator  

Microsoft Academic Search

Consideration is given to the properties of a surface spin wave converter of meander type consisting of a YIG film deposited on a single-crystal ferrite substrate. The impedance of the device is determined, and the resonant frequency and q-factor of a resonator based on such a converter are evaluated. Results are presented for a YIG\\/ferrite resonator whose q-factor is of

G. A. Vugalter

1980-01-01

443

Dynamically generated hadron resonances  

SciTech Connect

As an example of dynamically generated resonances we mention the interaction of vector mesons with baryons within the local hidden gauge formalism which gives rise to a large amount of such states, many of which can be associated to known resonances, while others represent predictions for new resonances. The width of these states coming from decay into pseudoscalar baryon is also addressed. We also mention recent states coming from {rho}{pi} interaction obtained with Faddeev equations.

Oset, E.; Gonzalez, P. [Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia-CSIC, Institutos de Investigacion de