Beam current enhancement of microwave plasma ion source utilizing double-port rectangular cavity resonator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Yuna; Park, Yeong-Shin; Jo, Jong-Gab

2012-02-15

Microwave plasma ion source with rectangular cavity resonator has been examined to improve ion beam current by changing wave launcher type from single-port to double-port. The cavity resonators with double-port and single-port wave launchers are designed to get resonance effect at TE-103 mode and TE-102 mode, respectively. In order to confirm that the cavities are acting as resonator, the microwave power for breakdown is measured and compared with the E-field strength estimated from the HFSS (High Frequency Structure Simulator) simulation. Langmuir probe measurements show that double-port cavity enhances central density of plasma ion source by modifying non-uniform plasma density profilemore » of the single-port cavity. Correspondingly, beam current from the plasma ion source utilizing the double-port resonator is measured to be higher than that utilizing single-port resonator. Moreover, the enhancement in plasma density and ion beam current utilizing the double-port resonator is more pronounced as higher microwave power applied to the plasma ion source. Therefore, the rectangular cavity resonator utilizing the double-port is expected to enhance the performance of plasma ion source in terms of ion beam extraction.« less

Beam current enhancement of microwave plasma ion source utilizing double-port rectangular cavity resonator.

PubMed

Lee, Yuna; Park, Yeong-Shin; Jo, Jong-Gab; Yang, J J; Hwang, Y S

2012-02-01

Microwave plasma ion source with rectangular cavity resonator has been examined to improve ion beam current by changing wave launcher type from single-port to double-port. The cavity resonators with double-port and single-port wave launchers are designed to get resonance effect at TE-103 mode and TE-102 mode, respectively. In order to confirm that the cavities are acting as resonator, the microwave power for breakdown is measured and compared with the E-field strength estimated from the HFSS (High Frequency Structure Simulator) simulation. Langmuir probe measurements show that double-port cavity enhances central density of plasma ion source by modifying non-uniform plasma density profile of the single-port cavity. Correspondingly, beam current from the plasma ion source utilizing the double-port resonator is measured to be higher than that utilizing single-port resonator. Moreover, the enhancement in plasma density and ion beam current utilizing the double-port resonator is more pronounced as higher microwave power applied to the plasma ion source. Therefore, the rectangular cavity resonator utilizing the double-port is expected to enhance the performance of plasma ion source in terms of ion beam extraction.

A Microwave Method for Dielectric Characterization Measurement of Small Liquids Using a Metamaterial-Based Sensor.

PubMed

Liu, Weina; Sun, Haoran; Xu, Lei

2018-05-05

We present a microwave method for the dielectric characterization of small liquids based on a metamaterial-based sensor The proposed sensor consists of a micro-strip line and a double split-ring resonator (SRR). A large electric field is observed on the two splits of the double SRRs at the resonance frequency (1.9 GHz). The dielectric property data of the samples under test (SUTs) were obtained with two measurements. One is with the sensor loaded with the reference liquid (REF) and the other is with the sensor loaded with the SUTs. Additionally, the principle of extracting permittivity from measured changes of resonance characteristics changes of the sensor loaded with REF and SUTs is given. Some measurements were carried out at 1.9 GHz, and the calculated results of methanol⁻water mixtures with different molar fractions agree well with the time-domain reflectometry method. Moreover, the proposed sensor is compact and highly sensitive for use of sub-wavelength resonance. In comparison with literature data, relative errors are less than 3% for the real parts and 2% for the imaginary parts of complex permittivity.

Resonance line transfer calculations by doubling thin layers. I - Comparison with other techniques. II - The use of the R-parallel redistribution function. [planetary atmospheres

NASA Technical Reports Server (NTRS)

Yelle, Roger V.; Wallace, Lloyd

1989-01-01

A versatile and efficient technique for the solution of the resonance line scattering problem with frequency redistribution in planetary atmospheres is introduced. Similar to the doubling approach commonly used in monochromatic scattering problems, the technique has been extended to include the frequency dependence of the radiation field. Methods for solving problems with external or internal sources and coupled spectral lines are presented, along with comparison of some sample calculations with results from Monte Carlo and Feautrier techniques. The doubling technique has also been applied to the solution of resonance line scattering problems where the R-parallel redistribution function is appropriate, both neglecting and including polarization as developed by Yelle and Wallace (1989). With the constraint that the atmosphere is illuminated from the zenith, the only difficulty of consequence is that of performing precise frequency integrations over the line profiles. With that problem solved, it is no longer necessary to use the Monte Carlo method to solve this class of problem.

Transmission loss of double wall panels containing Helmholtz resonators

NASA Technical Reports Server (NTRS)

Prydz, R. A.; Kuntz, H. L.; Morrow, D. L.; Wirt, L. S.

1988-01-01

Data and an analysis are presented on the use of Helholtz resonators in double wall panels (i.e., aircraft sidewalls). Several wall materials and resonator configurations were tested, and the resonators were found to substantially increase the transmission loss of the double wall system at the tuning frequency.

Transmission loss of double wall panels containing Helmholtz resonators

NASA Astrophysics Data System (ADS)

Prydz, R. A.; Kuntz, H. L.; Morrow, D. L.; Wirt, L. S.

Data and an analysis are presented on the use of Helholtz resonators in double wall panels (i.e., aircraft sidewalls). Several wall materials and resonator configurations were tested, and the resonators were found to substantially increase the transmission loss of the double wall system at the tuning frequency.

Laser frequency stabilization by light shift of optical-magnetic double resonances

NASA Astrophysics Data System (ADS)

Zhan, Yuanzhi; Peng, Xiang; Lin, Zaisheng; Gong, Wei; Guo, Hong

2015-05-01

This work adopts the light shift of optical-magnetic double resonance frequency in metastable-state 4He atoms to lock the laser center frequency to the magic point. At this magic frequency, both the left-circularly and right-circularly optical pumping processes will give the same value of optical-magnetic double resonance. With this method and after locking, experimental results show that the laser frequency fluctuation is dramatically reduced to 2.79 MHz in 3600 seconds, comparing with 34.1 MHz drift in the free running mode. In application, with the locked magic laser frequency, the heading error for laser pumped 4He magnetometer can be eliminated much. The National Science Fund for Distinguished Young Scholars of China (Grant No. 61225003), the National Natural Science Foundation of China (Grant No. 61101081), and the National Hi-Tech Research and Development (863) Program.

Herpin effective media resonant underlayers and resonant overlayer designs for ultra-high NA interference lithography.

PubMed

Bourke, Levi; Blaikie, Richard J

2017-12-01

Dielectric waveguide resonant underlayers are employed in ultra-high NA interference photolithography to effectively double the depth of field. Generally a single high refractive index waveguiding layer is employed. Here multilayer Herpin effective medium methods are explored to develop equivalent multilayer waveguiding layers. Herpin equivalent resonant underlayers are shown to be suitable replacements provided at least one layer within the Herpin trilayer supports propagating fields. In addition, a method of increasing the intensity incident upon the photoresist using resonant overlayers is also developed. This method is shown to greatly enhance the intensity within the photoresist making the use of thicker, safer, non-absorbing, low refractive index matching liquids potentially suitable for large-scale applications.

Quasi-stationary states of an electron with linearly dependent effective mass in an open nanostructure within transmission coefficient and S-matrix methods

NASA Astrophysics Data System (ADS)

Seti, Julia; Tkach, Mykola; Voitsekhivska, Oxana

2018-03-01

The exact solutions of the Schrödinger equation for a double-barrier open semiconductor plane nanostructure are obtained by using two different approaches, within the model of the rectangular potential profile and the continuous position-dependent effective mass of the electron. The transmission coefficient and scattering matrix are calculated for the double-barrier nanostructure. The resonance energies and resonance widths of the electron quasi-stationary states are analyzed as a function of the size of the near-interface region between wells and barriers, where the effective mass linearly depends on the coordinate. It is established that, in both methods, the increasing size affects in a qualitatively similar way the spectral characteristics of the states, shifting the resonance energies into the low- or high-energy region and increasing the resonance widths. It is shown that the relative difference of resonance energies and widths of a certain state, obtained in the model of position-dependent effective mass and in the widespread abrupt model in physically correct range of near-interface sizes, does not exceed 0.5% and 5%, respectively, independently of the other geometrical characteristics of the structure.

Measurement of Rate Constants for Homodimer Subunit Exchange Using Double Electron-Electron Resonance and Paramagnetic Relaxation Enhancements

PubMed Central

Yang, Yunhuang; Ramelot, Theresa A.; Ni, Shuisong; McCarrick, Robert M.; Kennedy, Michael A.

2013-01-01

Here, we report novel methods to measure rate constants for homodimer subunit exchange using double electron-electron resonance (DEER) electron paramagnetic resonance spectroscopy measurements and nuclear magnetic resonance spectroscopy based paramagnetic relaxation enhancement (PRE) measurements. The techniques were demonstrated using the homodimeric protein Dsy0195 from the strictly anaerobic bacterium Desulfitobacterium hafniense Y51. At specific times following mixing site-specific MTSL-labeled Dsy0195 with uniformly 15N-labeled Dsy0195, the extent of exchange was determined either by monitoring the decrease of MTSL-labeled homodimer from the decay of the DEER modulation depth or by quantifying the increase of MTSL-labeled/15N-labeled heterodimer using PREs. Repeated measurements at several time points following mixing enabled determination of the homodimer subunit dissociation rate constant, k−1;, which was 0.037 ± 0.005 min−1 derived from DEER experiments with a corresponding half-life time of 18.7 minutes. These numbers agreed with independent measurements obtained from PRE experiments. These methods can be broadly applied to protein-protein and protein-DNA complex studies. PMID:23180051

Resonant Raman scattering of double wall carbon nanotubes prepared by chemical vapor deposition method

NASA Astrophysics Data System (ADS)

Ci, Lijie; Zhou, Zhenping; Yan, Xiaoqin; Liu, Dongfang; Yuan, Huajun; Song, Li; Gao, Yan; Wang, Jianxiong; Liu, Lifeng; Zhou, Weiya; Wang, Gang; Xie, Sishen; Tan, Pingheng

2003-11-01

Resonant Raman spectra of double wall carbon nanotubes (DWCNTs), with diameters from 0.4 to 3.0 nm, were investigated with several laser excitations. The peak position and line shape of Raman bands were shown to be strongly dependent on the laser energies. With different excitations, the diameter and chirality of the DWCNTs can be discussed in detail. We show that tubes (the inner or outer layers of DWCNTs) with all kinds of chiralities could be synthesized, and a DWCNT can have any combination of chiralities of the inner and outer tubes.

Double-labeled donor probe can enhance the signal of fluorescence resonance energy transfer (FRET) in detection of nucleic acid hybridization

PubMed Central

Okamura, Yukio; Kondo, Satoshi; Sase, Ichiro; Suga, Takayuki; Mise, Kazuyuki; Furusawa, Iwao; Kawakami, Shigeki; Watanabe, Yuichiro

2000-01-01

A set of fluorescently-labeled DNA probes that hybridize with the target RNA and produce fluorescence resonance energy transfer (FRET) signals can be utilized for the detection of specific RNA. We have developed probe sets to detect and discriminate single-strand RNA molecules of plant viral genome, and sought a method to improve the FRET signals to handle in vivo applications. Consequently, we found that a double-labeled donor probe labeled with Bodipy dye yielded a remarkable increase in fluorescence intensity compared to a single-labeled donor probe used in an ordinary FRET. This double-labeled donor system can be easily applied to improve various FRET probes since the dependence upon sequence and label position in enhancement is not as strict. Furthermore this method could be applied to other nucleic acid substances, such as oligo RNA and phosphorothioate oligonucleotides (S-oligos) to enhance FRET signal. Although the double-labeled donor probes labeled with a variety of fluorophores had unexpected properties (strange UV-visible absorption spectra, decrease of intensity and decay of donor fluorescence) compared with single-labeled ones, they had no relation to FRET enhancement. This signal amplification mechanism cannot be explained simply based on our current results and knowledge of FRET. Yet it is possible to utilize this double-labeled donor system in various applications of FRET as a simple signal-enhancement method. PMID:11121494

A New Equivalence Theory Method for Treating Doubly Heterogeneous Fuel - I. Theory

DOE PAGES

Williams, Mark L.; Lee, Deokjung; Choi, Sooyoung

2015-03-04

A new methodology has been developed to treat resonance self-shielding in doubly heterogeneous very high temperature gas-cooled reactor systems in which the fuel compact region of a reactor lattice consists of small fuel grains dispersed in a graphite matrix. This new method first homogenizes the fuel grain and matrix materials using an analytically derived disadvantage factor from a two-region problem with equivalence theory and intermediate resonance method. This disadvantage factor accounts for spatial self-shielding effects inside each grain within the framework of an infinite array of grains. Then the homogenized fuel compact is self-shielded using a Bondarenko method to accountmore » for interactions between the fuel compact regions in the fuel lattice. In the final form of the equations for actual implementations, the double-heterogeneity effects are accounted for by simply using a modified definition of a background cross section, which includes geometry parameters and cross sections for both the grain and fuel compact regions. With the new method, the doubly heterogeneous resonance self-shielding effect can be treated easily even with legacy codes programmed only for a singly heterogeneous system by simple modifications in the background cross section for resonance integral interpolations. This paper presents a detailed derivation of the new method and a sensitivity study of double-heterogeneity parameters introduced during the derivation. The implementation of the method and verification results for various test cases are presented in the companion paper.« less

[Subcortical laminar heterotopia 'double cortex syndrome'].

PubMed

Teplyshova, A M; Gaskin, V V; Kustov, G V; Gudkova, A A; Luzin, R V; Trifonov, I S; Lebedeva, A V

2017-01-01

This article presents a clinical case of a 29-year-old patient with 'Double cortex syndrome' with epilepsy, intellectual and mental disorders. Subcortical band heterotopia is a rare disorder of neuronal migration. Such patients typically present with epilepsy and variable degrees of mental retardation and behavioral and intellectual disturbances. The main diagnostic method is magnetic resonance imaging (MRI).

Resonant Tunneling in Photonic Double Quantum Well Heterostructures.

PubMed

Cox, Joel D; Singh, Mahi R

2010-01-30

Here, we study the resonant photonic states of photonic double quantum well (PDQW) heterostructures composed of two different photonic crystals. The heterostructure is denoted as B/A/B/A/B, where photonic crystals A and B act as photonic wells and barriers, respectively. The resulting band structure causes photons to become confined within the wells, where they occupy discrete quantized states. We have obtained an expression for the transmission coefficient of the PDQW heterostructure using the transfer matrix method and have found that resonant states exist within the photonic wells. These resonant states occur in split pairs, due to a coupling between degenerate states shared by each of the photonic wells. It is observed that when the resonance energy lies at a bound photonic state and the two photonic quantum wells are far away from each other, resonant states appear in the transmission spectrum of the PDQW as single peaks. However, when the wells are brought closer together, coupling between bound photonic states causes an energy-splitting effect, and the transmitted states each have two peaks. Essentially, this means that the system can be switched between single and double transparent states. We have also observed that the total number of resonant states can be controlled by varying the width of the photonic wells, and the quality factor of transmitted peaks can be drastically improved by increasing the thickness of the outer photonic barriers. It is anticipated that the resonant states described here can be used to develop new types of photonic-switching devices, optical filters, and other optoelectronic devices.

Mean grain size detection of DP590 steel plate using a corrected method with electromagnetic acoustic resonance.

PubMed

Wang, Bin; Wang, Xiaokai; Hua, Lin; Li, Juanjuan; Xiang, Qing

2017-04-01

Electromagnetic acoustic resonance (EMAR) is a considerable method to determine the mean grain size of the metal material with a high precision. The basic ultrasonic attenuation theory used for the mean grain size detection of EMAR is come from the single phase theory. In this paper, the EMAR testing was carried out based on the ultrasonic attenuation theory. The detection results show that the double peaks phenomenon occurs in the EMAR testing of DP590 steel plate. The dual phase structure of DP590 steel is the inducement of the double peaks phenomenon in the EMAR testing. In reaction to the phenomenon, a corrected method with EMAR was put forward to detect the mean grain size of dual phase steel. Compared with the traditional attenuation evaluation method and the uncorrected method with EMAR, the corrected method with EMAR shows great effectiveness and superiority for the mean grain size detection of DP590 steel plate. Copyright © 2016. Published by Elsevier B.V.

The use of acoustically tuned resonators to improve the sound transmission loss of double-panel partitions

NASA Astrophysics Data System (ADS)

Mason, J. M.; Fahy, F. J.

1988-07-01

Double-leaf partitions are often utilized in situations requiring low weight structures with high transmission loss, an example of current interest being the fuselage walls of propeller-driven aircraft. In this case, acoustic excitation is periodic and, if one of the frequencies of excitation lies in the region of the fundamental mass-air-mass frequency of the partition, insulation performance is considerably less than desired. The potential effectiveness of tuned Helmholtz resonators connected to the partition cavity is investigated as a method of improving transmission loss. This is demonstrated by a simple theoretical model and then experimentally verified. Results show that substantial improvements may be obtained at and around the mass-air-mass frequency for a total resonator volume 15 percent of the cavity volume.

Double-Resonance Facilitated Decomposion of Emission Spectra

NASA Astrophysics Data System (ADS)

Kato, Ryota; Ishikawa, Haruki

2016-06-01

Emission spectra provide us with rich information about the excited-state processes such as proton-transfer, charge-transfer and so on. In the cases that more than one excited states are involved, emission spectra from different excited states sometimes overlap and a decomposition of the overlapped spectra is desired. One of the methods to perform a decomposition is a time-resolved fluorescence technique. It uses a difference in time evolutions of components involved. However, in the gas-phase, a concentration of the sample is frequently too small to carry out this method. On the other hand, double-resonance technique is a very powerful tool to discriminate or identify a common species in the spectra in the gas-phase. Thus, in the present study, we applied the double-resonance technique to resolve the overlapped emission spectra. When transient IR absorption spectra of the excited state are available, we can label the population of the certain species by the IR excitation with a proper selection of the IR wavenumbers. Thus, we can obtain the emission spectra of labeled species by subtracting the emission spectra with IR labeling from that without IR. In the present study, we chose the charge-transfer emission spectra of cyanophenyldisilane (CPDS) as a test system. One of us reported that two charge-transfer (CT) states are involved in the intramolecular charge-transfer (ICT) process of CPDS-water cluster and recorded the transient IR spectra. As expected, we have succeeded in resolving the CT emission spectra of CPDS-water cluster by the double resonance facilitated decomposion technique. In the present paper, we will report the details of the experimental scheme and the results of the decomposition of the emission spectra. H. Ishikawa, et al., Chem. Phys. Phys. Chem., 9, 117 (2007).

Electrically tunable Dicke effect in a double-ring resonator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cetin, A. E.; Muestecaplioglu, Oe. E.; Department of Physics, Koc University, Sariyer, Istanbul 34450

We study the finite-element method analysis of the Dicke effect using numerical simulations in an all-optical system of an optical waveguide side-coupled to two interacting ring resonators in a liquid crystal environment. The system is shown to exhibit all the signatures of the Dicke effect under active and reversible control by an applied voltage.

Observation of millimeter-wave oscillations from resonant tunneling diodes and some theoretical considerations of ultimate frequency limits

NASA Technical Reports Server (NTRS)

Sollner, T. C. L. G.; Brown, E. R.; Goodhue, W. D.; Le, H. Q.

1987-01-01

Recent observations of oscillation frequencies up to 56 GHz in resonant tunneling structures are discussed in relation to calculations by several authors of the ultimate frequency limits of these devices. It is found that calculations relying on the Wentzel-Kramers-Brillouin (WKB) approximation give limits well below the observed oscillation frequencies. Two other techniques for calculating the upper frequency limit were found to give more reasonable results. One method employs the solution of the time-dependent Schroedinger equation obtained by Kundrotas and Dargys (1986); the other uses the energy width of the transmission function for electrons through the double-barrier structure. This last technique is believed to be the most accurate since it is based on general results for the lifetime of any resonant state. It gives frequency limits on the order of 1 THz for two recently fabricated structures. It appears that the primary limitation of the oscillation frequency for double-barrier resonant-tunneling diodes is imposed by intrinsic device circuit parameters and by the transit time of the depletion layer rather than by time delays encountered in the double-barrier region.

Generation of tunable double Fano resonances by plasmon hybridization in graphene–metal metamaterial

NASA Astrophysics Data System (ADS)

Yan, Zhendong; Qian, Lina; Zhan, Peng; Wang, Zhenlin

2018-07-01

We proposed the excitation of double Fano resonances by the destructive interference between the narrow electric symmetric/antisymmetric resonant modes formed by plasmon hybridization and a broad magnetic dipole resonance in a novel hybrid metamaterial composed of periodically patterned stacked graphene–ribbon pairs and gold split-ring resonators. The double Fano transparency windows in this hybrid metamaterial can be actively controlled by tuning the Fermi energy of graphene through the use of electric gating and its electronic mobility. Our designed dual Fano resonances exhibit a large group index associated with the resonance response in the transparency windows, suggesting promising applications in nanophotonics, such as a slow light device.

Visualization of macrophage recruitment in head and neck carcinoma model using fluorine-19 magnetic resonance imaging.

PubMed

Khurana, Aman; Chapelin, Fanny; Xu, Hongyan; Acevedo, Joseph R; Molinolo, Alfred; Nguyen, Quyen; Ahrens, Eric T

2018-04-01

To evaluate the role of infiltrating macrophages in murine models of single and double mutation head and neck tumors using a novel fluorine-19 ( 19 F) MRI technology. Tumor cell lines single-hit/SCC4 or double-hit/Cal27, with mutations of TP53 and TP53 & FHIT, respectively, were injected bilaterally into the flanks of (n = 10) female mice. With tumors established, perfluorocarbon nanoemulsion was injected intravenously, which labels in situ predominantly monocytes and macrophages. Longitudinal spin density-weighted 19 F MRI data enabled quantification of the macrophage burden in tumor and surrounding tissue. The average number of 19 F atoms within the tumors was twice as high in the Cal27 group compared with SCC4 (3.9 × 10 19 and 2.0 × 10 19 19 F/tumor, respectively; P = 0.0034) two days after contrast injection, signifying increased tumor-associated macrophages in double-hit tumors. The difference was still significant 10 days after injection. Histology stains correlated with in vivo results, exhibiting numerous perfluorocarbon-labeled macrophages in double-hit tumors and to a lesser extent in single-hit tumors. This study helps to establish 19 F MRI as a method for quantifying immune cells in the tumor microenvironment, allowing distinction between double and single-hit head and neck tumors. This technique would be extremely valuable in the clinic for pretreatment planning, prognostics, and post-treatment surveillance. Magn Reson Med 79:1972-1980, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Methods Development for Spectral Simplification of Room-Temperature Rotational Spectra

NASA Astrophysics Data System (ADS)

Kent, Erin B.; Shipman, Steven

2014-06-01

Room-temperature rotational spectra are dense and difficult to assign, and so we have been working to develop methods to accelerate this process. We have tested two different methods with our waveguide-based spectrometer, which operates from 8.7 to 26.5 GHz. The first method, based on previous work by Medvedev and De Lucia, was used to estimate lower state energies of transitions by performing relative intensity measurements at a range of temperatures between -20 and +50 °C. The second method employed hundreds of microwave-microwave double resonance measurements to determine level connectivity between rotational transitions. The relative intensity measurements were not particularly successful in this frequency range (the reasons for this will be discussed), but the information gleaned from the double-resonance measurements can be incorporated into other spectral search algorithms (such as autofit or genetic algorithm approaches) via scoring or penalty functions to help with the spectral assignment process. I.R. Medvedev, F.C. De Lucia, Astrophys. J. 656, 621-628 (2007).

Bifurcations and Chaos of AN Immersed Cantilever Beam in a Fluid and Carrying AN Intermediate Mass

NASA Astrophysics Data System (ADS)

AL-QAISIA, A. A.; HAMDAN, M. N.

2002-06-01

The concern of this work is the local stability and period-doubling bifurcations of the response to a transverse harmonic excitation of a slender cantilever beam partially immersed in a fluid and carrying an intermediate lumped mass. The unimodal form of the non-linear dynamic model describing the beam-mass in-plane large-amplitude flexural vibration, which accounts for axial inertia, non-linear curvature and inextensibility condition, developed in Al-Qaisia et al. (2000Shock and Vibration7 , 179-194), is analyzed and studied for the resonance responses of the first three modes of vibration, using two-term harmonic balance method. Then a consistent second order stability analysis of the associated linearized variational equation is carried out using approximate methods to predict the zones of symmetry breaking leading to period-doubling bifurcation and chaos on the resonance response curves. The results of the present work are verified for selected physical system parameters by numerical simulations using methods of the qualitative theory, and good agreement was obtained between the analytical and numerical results. Also, analytical prediction of the period-doubling bifurcation and chaos boundaries obtained using a period-doubling bifurcation criterion proposed in Al-Qaisia and Hamdan (2001 Journal of Sound and Vibration244, 453-479) are compared with those of computer simulations. In addition, results of the effect of fluid density, fluid depth, mass ratio, mass position and damping on the period-doubling bifurcation diagrams are studies and presented.

Study of working principle and thermal balance process of a double longitudinal-mode He-Ne laser

NASA Astrophysics Data System (ADS)

Wang, Li-qiang

2009-07-01

A double longitudinal mode He-Ne laser with frequency stabilization is proposed. Compared with general methods, such as Lamb dip, Zeeman splitting and molecule saturation absorption method, this design has some advantages, such as no piezocrystal or magnetic field, a short frequency-stabilized time, lower cost, and higher frequency stability and reproducibility. The metal wire is uniformly wrapped on the discharge tube of the laser. When the metal wire is heated up, the resonant cavity changes with the temperature field around the discharge tube to make the frequency of the laser to be tuned. The polarizations of the two longitudinal modes from the laser must be orthogonal. The parallelly polarized light and the vertically polarized light compete with each other, i. e., the parallelly polarized light generates a larger output power, while, the vertically polarized light correspondingly generates a smaller one, but an equal value is found at the reference frequencies by automatically adjusting the length of the resonant cavity, due to change of the temperature in the discharge tube. Consequently the frequencies of the laser are stabilized. In my experiment, an intracavity He-Ne laser whose length of the resonant cavity is larger than 50mm and smaller than 300mm is selected for the double longitudinal-mode laser. Influence factors of frequency stability of this laser is only change of the length of the resonant cavity. The laser includes three stages: mode hopping, transition stage, and modes stability from startup to laser stability. When this laser is in modes stability, the waveform of heating metal wire is observed to a pulse whose duty is almost 50%, and thermal balances of the resonant cavity mainly rely on discharge tube.

Coplanar Waveguide Radial Line Double Stub and Application to Filter Circuits

NASA Technical Reports Server (NTRS)

Simons, R. N.; Taub, S. R.

1993-01-01

Coplanar waveguide (CPW) and grounded coplanar waveguide (GCPW) radial line double stub resonators are experimentally characterized with respect to stub radius and sector angle. A simple closed-form design equation, which predicts the resonance radius of the stub, is presented. Use of a double stub resonator as a lowpass filter or as a harmonic suppression filter is demonstrated, and design rules are given.

Field-incidence noise transmission loss of general aviation aircraft double wall configurations

NASA Astrophysics Data System (ADS)

Grosveld, F. W.

1984-01-01

Theoretical formulations have been developed to describe the transmission of reverberant sound through an infinite, semi-infinite and a finite double panel structure. The model incorporates the fundamental resonance frequencies of each of the panels, the mass-air-mass resonances of the structure, the standing wave resonances in the cavity between the panels and finally the coincidence resonance regions, where the exciting sound pressure wave and flexural waves of each of the panels coincide. It is shown that phase cancellation effects of pressure waves reflected from the cavity boundaries back into the cavity allows the transmission loss of a finite double panel structure to be approximated by a finite double panel mounted in an infinite baffle having no cavity boundaries. Comparison of the theory with high quality transmission loss data yields good agreement in the mass-controlled frequency region. It is shown that the application of acoustic blankets to the double panel structure does not eliminate the mass-air-mass resonances if those occur at low frequencies. It is concluded that this frequency region of low noise transmission loss is a potential interior noise problem area for propeller driven aircraft having a double panel fuselage construction.

Modeling and characterization of double resonant tunneling diodes for application as energy selective contacts in hot carrier solar cells

NASA Astrophysics Data System (ADS)

Jehl, Zacharie; Suchet, Daniel; Julian, Anatole; Bernard, Cyril; Miyashita, Naoya; Gibelli, Francois; Okada, Yoshitaka; Guillemolles, Jean-Francois

2017-02-01

Double resonant tunneling barriers are considered for an application as energy selective contacts in hot carrier solar cells. Experimental symmetric and asymmetric double resonant tunneling barriers are realized by molecular beam epitaxy and characterized by temperature dependent current-voltage measurements. The negative differential resistance signal is enhanced for asymmetric heterostructures, and remains unchanged between low- and room-temperatures. Within Tsu-Esaki description of the tunnel current, this observation can be explained by the voltage dependence of the tunnel transmission amplitude, which presents a resonance under finite bias for asymmetric structures. This effect is notably discussed with respect to series resistance. Different parameters related to the electronic transmission of the structure and the influence of these parameters on the current voltage characteristic are investigated, bringing insights on critical processes to optimize in double resonant tunneling barriers applied to hot carrier solar cells.

Microwave noise measurements on double barrier resonant tunneling diodes

NASA Astrophysics Data System (ADS)

Kwaspen, J. J. M.; Heyker, H. C.; Demarteau, J. I. M.; Vanderoer, T. G.

1990-12-01

Double Barrier Resonant Tunneling (DBRT) diodes have nonlinear current voltage characteristics with Negative Differential Resistance (NDR) regions. Biased in one of these NDR regions, the DBRT diode can be used for microwave amplification purposes, so knowledge of the diode's noise behavior is important from a physics point of view. Two noise parameter measurement methods were developed in which the DBRT diode is used in a reflection amplifier configuration with circulator to transform the active one port device into an active two port with separate input and output ports. The Noise Figure (NF) of the DBRT diode must be deembedded from the NF of the reflection amplifier. An equation for the NF of the DBRT diode is derived. Two different measurement methods are used. A (complicated) more exact method uses the measured S parameters of the actual circulator and accounts for reflections at the noise source, NF meter and DBRT diode. A mathematically simple method (three versions) uses only scalar data collected by the NF meter. The results from these two methods are compared and they coincide well.

Complex absorbing potentials within EOM-CC family of methods: Theory, implementation, and benchmarks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zuev, Dmitry; Jagau, Thomas-C.; Krylov, Anna I.

2014-07-14

A production-level implementation of equation-of-motion coupled-cluster singles and doubles (EOM-CCSD) for electron attachment and excitation energies augmented by a complex absorbing potential (CAP) is presented. The new method enables the treatment of metastable states within the EOM-CC formalism in a similar manner as bound states. The numeric performance of the method and the sensitivity of resonance positions and lifetimes to the CAP parameters and the choice of one-electron basis set are investigated. A protocol for studying molecular shape resonances based on the use of standard basis sets and a universal criterion for choosing the CAP parameters are presented. Our resultsmore » for a variety of π{sup *} shape resonances of small to medium-size molecules demonstrate that CAP-augmented EOM-CCSD is competitive relative to other theoretical approaches for the treatment of resonances and is often able to reproduce experimental results.« less

Evidence for two interconverting protein isomers in the methotrexate complex of dihydrofolate reductase from Escherichia coli

DOE Office of Scientific and Technical Information (OSTI.GOV)

Falzone, C.J.; Benkovic, S.J.; Wright, P.E.

1991-02-26

Two-dimensional {sup 1}H NMR methods and a knowledge of the X-ray crystal structure have been used to make resonance assignments for the amino acid side chains of dihydrofolate reductase from Escherichia coli complexed with methotrexate. The H7 proton on the pteridine ring of methotrexate was found to have NOEs to the methyl protons of Leu-28 which were assigned by using the L28F mutant. These NOEs indicated that the orientation of the methotrexate pteridine ring is similar in both solution and crystal structures. During the initial assignment process, it became evident that many of the resonances in this complex, unlike thosemore » of the folate complex, are severally broadened or doubled. The observation of two distinct sets of resonances in a ratio of approximately 2:1 was attributed to the presence of two protein isomers. Many of the side chains with clearly doubled resonances were located in the {beta}-sheet and the active site. Preliminary studies on the apoprotein also revealed doubled resonances in the absence of the inhibitor, indicating the existence of the protein isomers prior to methotrexate binding. In contrast to the methotrexate complex, the binary complex with folate and the ternary MTX-NADPH-DHFR complex presented a single enzyme form. These results are proposed to reflect the ability of folate and NADPH to bind predominantly to one protein isomer.« less

Entangling distant resonant exchange qubits via circuit quantum electrodynamics

NASA Astrophysics Data System (ADS)

Srinivasa, V.; Taylor, J. M.; Tahan, Charles

2016-11-01

We investigate a hybrid quantum system consisting of spatially separated resonant exchange qubits, defined in three-electron semiconductor triple quantum dots, that are coupled via a superconducting transmission line resonator. Drawing on methods from circuit quantum electrodynamics and Hartmann-Hahn double resonance techniques, we analyze three specific approaches for implementing resonator-mediated two-qubit entangling gates in both dispersive and resonant regimes of interaction. We calculate entangling gate fidelities as well as the rate of relaxation via phonons for resonant exchange qubits in silicon triple dots and show that such an implementation is particularly well suited to achieving the strong coupling regime. Our approach combines the favorable coherence properties of encoded spin qubits in silicon with the rapid and robust long-range entanglement provided by circuit QED systems.

New Tunneling Features in Polar III-Nitride Resonant Tunneling Diodes

NASA Astrophysics Data System (ADS)

Encomendero, Jimy; Faria, Faiza Afroz; Islam, S. M.; Protasenko, Vladimir; Rouvimov, Sergei; Sensale-Rodriguez, Berardi; Fay, Patrick; Jena, Debdeep; Xing, Huili Grace

2017-10-01

For the past two decades, repeatable resonant tunneling transport of electrons in III-nitride double barrier heterostructures has remained elusive at room temperature. In this work we theoretically and experimentally study III-nitride double-barrier resonant tunneling diodes (RTDs), the quantum transport characteristics of which exhibit new features that are unexplainable using existing semiconductor theory. The repeatable and robust resonant transport in our devices enables us to track the origin of these features to the broken inversion symmetry in the uniaxial crystal structure, which generates built-in spontaneous and piezoelectric polarization fields. Resonant tunneling transport enabled by the ground state as well as by the first excited state is demonstrated for the first time over a wide temperature window in planar III-nitride RTDs. An analytical transport model for polar resonant tunneling heterostructures is introduced for the first time, showing a good quantitative agreement with experimental data. From this model we realize that tunneling transport is an extremely sensitive measure of the built-in polarization fields. Since such electric fields play a crucial role in the design of electronic and photonic devices, but are difficult to measure, our work provides a completely new method to accurately determine their magnitude for the entire class of polar heterostructures.

A series of compact rejection filters based on the interaction between spoof SPPs and CSRRs.

PubMed

Zhang, Qian; Zhang, Hao Chi; Yin, Jia Yuan; Pan, Bai Cao; Cui, Tie Jun

2016-06-21

We propose a method to synthesize several band-rejection filters by etching split-ring resonators (SRRs) on the transmission line for spoof surface plasmon polaritons (SPPs), which is made of double-side or single-side corrugated metal strips. From dispersion relations, the corrugated strips can support spoof SPP modes when the operating frequency is less than the cutoff frequency. The electric field component perpendicular to the strip surface of the SPP modes can excite the complementary SRRs (CSRRs), leading to resonant modes preventing the SPP propagation near the resonant frequencies. Using this principle, single-frequency rejection filters, double-frequency rejection filters, and broad band-stop filters with bandwidth of 1.5 GHz have been designed and fabricated using the single- and/or double-side corrugated strips. Both measured results and numerical simulations demonstrate the excellent filtering characteristics of all design, which are in good agreements. The isolation of all filters can be less than -20 dB, and even reach to -38 dB at rejection frequencies. The proposed rejection and stop-band filters give important potentials to develop integrated plasmonic functional devices and circuits at microwave and terahertz frequencies.

Resonance capture and dynamics of three-planet systems

NASA Astrophysics Data System (ADS)

Charalambous, C.; Martí, J. G.; Beaugé, C.; Ramos, X. S.

2018-06-01

We present a series of dynamical maps for fictitious three-planet systems in initially circular coplanar orbits. These maps have unveiled a rich resonant structure involving two or three planets, as well as indicating possible migration routes from secular to double resonances or pure three-planet commensurabilities. These structures are then compared to the present-day orbital architecture of observed resonant chains. In a second part of the paper, we describe N-body simulations of type-I migration. Depending on the orbital decay time-scale, we show that three-planet systems may be trapped in different combinations of independent commensurabilities: (i) double resonances, (ii) intersection between a two-planet and a first-order three-planet resonances, and (iii) simultaneous libration in two first-order three-planet resonances. These latter outcomes are found for slow migrations, while double resonances are almost always the final outcome in high-density discs. Finally, we discuss an application to the TRAPPIST-1 system. We find that, for low migration rates and planetary masses of the order of the estimated values, most three-planet sub-systems are able to reach the observed double resonances after following evolutionary routes defined by pure three-planet resonances. The final orbital configuration shows resonance offsets comparable with present-day values without the need of tidal dissipation. For the 8/5 resonance proposed to dominate the dynamics of the two inner planets, we find little evidence of its dynamical significance; instead, we propose that this relation between mean motions could be a consequence of the interaction between a pure three-planet resonance and a two-planet commensurability between planets c and d.

A metamaterial terahertz modulator based on complementary planar double-split-ring resonator

NASA Astrophysics Data System (ADS)

Wang, Chang-hui; Kuang, Deng-feng; Chang, Sheng-jiang; Lin, Lie

2013-07-01

A metamaterial based on complementary planar double-split-ring resonator (DSRR) structure is presented and demonstrated, which can optically tune the transmission of the terahertz (THz) wave. Unlike the traditional DSRR metamaterials, the DSRR discussed in this paper consists of two split rings connected by two bridges. Numerical simulations with the finite-difference time-domain (FDTD) method reveal that the transmission spectra of the original and the complementary metamaterials are both in good agreement with Babinet's principle. Then by increasing the carrier density of the intrinsic GaAs substrate, the magnetic response of the complementary special DSRR metamaterial can be weakened or even turned off. This metamaterial structure is promised to be a narrow-band THz modulator with response time of several nanoseconds.

Resonance Frequency Tuning of a Double Ring Resonator in GaInAsP/InP: Experiment and Simulation

NASA Astrophysics Data System (ADS)

Rabus, Dominik Gerhard; Hamacher, Michael; Heidrich, Helmut

2002-02-01

A racetrack shaped double ring resonator (DRR) filter is demonstrated with radii of 200 μm. The double ring resonator contains two -3 dB multimode interference (MMI) couplers for I/O coupling and a -13 dB codirectional coupler in between the rings. A free spectral range of 50 GHz has been realized. A simulation model has been developed to describe the DRR. As fabrication tolerances do not allow the realization of two identical rings with required nm-circumference accuracy in the resonator, a frequency alignment of the resonator is indispensable. The resonance frequency tuning is performed thermally using platinum resistors which have been placed on top of the waveguides in both rings. An on-off ratio increase has been achieved of more than 3 dB, resulting in a total on-off ratio larger than 18 dB. The frequency alignment is inevitable in the case of multiple coupled micro ring resonators.

Study on the interaction between albendazole and eosin Y by fluorescence, resonance Rayleigh scattering and frequency doubling scattering spectra and their analytical applications

NASA Astrophysics Data System (ADS)

Tian, Fengling; Huang, Wei; Yang, Jidong; Li, Qin

In pH 3.25-3.35 Britton-Robinson (BR) buffer solution, albendazole (ABZ) could react with eosin Y (EY) to form a 1:1 ion-association complex, which not only results in the quenching of fluorescence, but also resulted in the great enhancement of resonance Rayleigh scattering (RRS) and frequency doubling scattering (FDS). Furthermore, a new RRS spectrum will appear, and the maximum RRS wavelength was located at about 356 nm. The detection limit for ABZ were 21.51 ng mL-1 for the fluorophotometry, 6.93 ng mL-1 for the RRS method and 12.89 ng mL-1 for the FDS method. Among them, the RRS method had the highest sensitivity. The experimental conditions were optimized and effects of coexisting substances were evaluated. Meanwhile, the influences of coexisting substances were tested. The methods have been successfully applied to the determination of ABZ in capsules and human urine samples. The composition and structure of the ion-association complex and the reaction mechanism were discussed.

Double-gated myocardial ASL perfusion imaging is robust to heart rate variation.

PubMed

Do, Hung Phi; Yoon, Andrew J; Fong, Michael W; Saremi, Farhood; Barr, Mark L; Nayak, Krishna S

2017-05-01

Cardiac motion is a dominant source of physiological noise (PN) in myocardial arterial spin labeled (ASL) perfusion imaging. This study investigates the sensitivity to heart rate variation (HRV) of double-gated myocardial ASL compared with the more widely used single-gated method. Double-gating and single-gating were performed on 10 healthy volunteers (n = 10, 3F/7M; age, 23-34 years) and eight heart transplant recipients (n = 8, 1F/7M; age, 26-76 years) at rest in the randomized order. Myocardial blood flow (MBF), PN, temporal signal-to-noise ratio (SNR), and HRV were measured. HRV ranged from 0.2 to 7.8 bpm. Double-gating PN did not depend on HRV, while single-gating PN increased with HRV. Over all subjects, double-gating provided a significant reduction in global PN (from 0.20 ± 0.15 to 0.11 ± 0.03 mL/g/min; P = 0.01) and per-segment PN (from 0.33 ± 0.23 to 0.21 ± 0.12 mL/g/min; P < 0.001), with significant increases in global temporal SNR (from 11 ± 8 to 18 ± 8; P = 0.02) and per-segment temporal SNR (from 7 ± 4 to 11 ± 12; P < 0.001) without significant difference in measured MBF. Single-gated myocardial ASL suffers from reduced temporal SNR, while double-gated myocardial ASL provides consistent temporal SNR independent of HRV. Magn Reson Med 77:1975-1980, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Control of slow-to-fast light and single-to-double optomechanically induced transparency in a compound resonator system: A theoretical approach

NASA Astrophysics Data System (ADS)

Ziauddin; Rahman, Mujeeb ur; Ahmad, Iftikhar; Qamar, Sajid

2017-10-01

The transmission characteristics of probe light field is investigated theoretically in a compound system of two coupled resonators. The proposed system consisted of two high-Q Fabry-Perot resonators in which one of the resonators is optomechanical. Optomechanically induced transparency (OMIT), having relatively large window, is noticed via strong coupling between the two resonators. We investigate tunable switching from single to double OMIT by increasing amplitude of the pump field. We notice that, control of slow and fast light can be obtained via the coupling strength between the two resonators.

Self-Reference Refractive Index Sensor Based on Independently Controlled Double Resonances in Side-Coupled U-Shaped Resonators.

PubMed

Ren, Xiaobin; Ren, Kun; Ming, Chengguo

2018-04-28

A plasmonic, refractive, index nanosensor is investigated theoretically and numerically in two U-shaped cavities side-coupled to a metal⁻dielectric⁻metal (MDM) waveguide. A transparency window between two transmission dips is observed. The physical origin of the transmission phenomenon is revealed by mapping the magnetic field distribution. Independent double resonances are realized through the proposed design. Double resonances showed diverse responses to the variations of the structural dimensions. In particular, they presented different dependences on a refraction index of the medium in an individual resonator. One resonance exhibited a remarkable shift with the increase of the refraction index; however, the other resonance remained unchanged. On the basis of this unique characteristic of differing sensitivities, self-reference sensing is discussed. The nanosensor yielded a high sensitivity of 917 nm/RIU and a figure of merit of 180 RIU −1 . This work is helpful in terms of the design of on-chip optical sensors with high sensitivity and improved detection accuracy in complicated environments.

The effect of transverse wave vector and magnetic fields on resonant tunneling times in double-barrier structures

NASA Astrophysics Data System (ADS)

Wang, Hongmei; Zhang, Yafei; Xu, Huaizhe

2007-01-01

The effect of transverse wave vector and magnetic fields on resonant tunneling times in double-barrier structures, which is significant but has been frequently omitted in previous theoretical methods, has been reported in this paper. The analytical expressions of the longitudinal energies of quasibound levels (LEQBL) and the lifetimes of quasibound levels (LQBL) in symmetrical double-barrier (SDB) structures have been derived as a function of transverse wave vector and longitudinal magnetic fields perpendicular to interfaces. Based on our derived analytical expressions, the LEQBL and LQBL dependence upon transverse wave vector and longitudinal magnetic fields has been explored numerically for a SDB structure. Model calculations show that the LEQBL decrease monotonically and the LQBL shorten with increasing transverse wave vector, and each original LEQBL splits to a series of sub-LEQBL which shift nearly linearly toward the well bottom and the lifetimes of quasibound level series (LQBLS) shorten with increasing Landau-level indices and magnetic fields.

Quantum beats in conductance oscillations in graphene-based asymmetric double velocity wells and electrostatic wells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Lei; Department of Medical Physics, Basic Medical College, Hebei Medical University, Shijiazhuang, Hebei 050017; Li, Yu-Xian

2014-01-14

The transport properties in graphene-based asymmetric double velocity well (Fermi velocity inside the well less than that outside the well) and electrostatic well structures are investigated using the transfer matrix method. The results show that quantum beats occur in the oscillations of the conductance for asymmetric double velocity wells. The beating effect can also be found in asymmetric double electrostatic wells, but only if the widths of the two wells are different. The beat frequency for the asymmetric double well is exactly equal to the frequency difference between the oscillation rates in two isolated single wells with the same structuresmore » as the individual wells in the double well structure. A qualitative interpretation is proposed based on the fact that the resonant levels depend upon the sizes of the quantum wells. The beating behavior can provide a new way to identify the symmetry of double well structures.« less

Accurate and simple method for quantification of hepatic fat content using magnetic resonance imaging: a prospective study in biopsy-proven nonalcoholic fatty liver disease.

PubMed

Hatta, Tomoko; Fujinaga, Yasunari; Kadoya, Masumi; Ueda, Hitoshi; Murayama, Hiroaki; Kurozumi, Masahiro; Ueda, Kazuhiko; Komatsu, Michiharu; Nagaya, Tadanobu; Joshita, Satoru; Kodama, Ryo; Tanaka, Eiji; Uehara, Tsuyoshi; Sano, Kenji; Tanaka, Naoki

2010-12-01

To assess the degree of hepatic fat content, simple and noninvasive methods with high objectivity and reproducibility are required. Magnetic resonance imaging (MRI) is one such candidate, although its accuracy remains unclear. We aimed to validate an MRI method for quantifying hepatic fat content by calibrating MRI reading with a phantom and comparing MRI measurements in human subjects with estimates of liver fat content in liver biopsy specimens. The MRI method was performed by a combination of MRI calibration using a phantom and double-echo chemical shift gradient-echo sequence (double-echo fast low-angle shot sequence) that has been widely used on a 1.5-T scanner. Liver fat content in patients with nonalcoholic fatty liver disease (NAFLD, n = 26) was derived from a calibration curve generated by scanning the phantom. Liver fat was also estimated by optical image analysis. The correlation between the MRI measurements and liver histology findings was examined prospectively. Magnetic resonance imaging measurements showed a strong correlation with liver fat content estimated from the results of light microscopic examination (correlation coefficient 0.91, P < 0.001) regardless of the degree of hepatic steatosis. Moreover, the severity of lobular inflammation or fibrosis did not influence the MRI measurements. This MRI method is simple and noninvasive, has excellent ability to quantify hepatic fat content even in NAFLD patients with mild steatosis or advanced fibrosis, and can be performed easily without special devices.

Enhanced optical transmission through double-overlapped annular aperture array

NASA Astrophysics Data System (ADS)

Wang, Chaonan; Bai, Ming; Jin, Ming

2012-07-01

In this paper, transmission properties through an array of concentric or eccentric double-overlapped annular apertures (CDOAAs or EDOAAs) are investigated. It is demonstrated that local surface plasmon-assisted TE11-like modes in CDOAAs exhibit a blue shift with the increasing overlapped factor. For EDOAAs with asymmetric annular apertures in both directions, a new resonant peak can be excited at a larger wavelength using linearly polarised light, which corresponds to extreme field localisation around the narrowest gap attributed to the gap plasmons' excitation and is quite sensitive to the offset of the eccentric centre island. These properties provide a possible method to achieve multiplexed and tunable wavelength selection using different local surface plasmon resonances and are of significant potential applicable value to the designing of tunable optical devices.

Parametric nonfeedback resonance in period doubling systems

NASA Astrophysics Data System (ADS)

Pisarchik, A. N.; Corbalán, R.

1999-02-01

Slow periodic modulation of a control parameter in a period doubling system leads to an interaction between stable and unstable periodic orbits. This causes a resonance in the system response at the modulation frequency. The conditions for this resonance are studied through numerical simulations of quadratic map and laser equations. The results are confirmed by experiments in a CO2 laser with modulated losses.

Comparison of various decentralised structural and cavity feedback control strategies for transmitted noise reduction through a double panel structure

NASA Astrophysics Data System (ADS)

Ho, Jen-Hsuan; Berkhoff, Arthur

2014-03-01

This paper compares various decentralised control strategies, including structural and acoustic actuator-sensor configuration designs, to reduce noise transmission through a double panel structure. The comparison is based on identical control stability indexes. The double panel structure consists of two panels with air in between and offers the advantages of low sound transmission at high frequencies, low heat transmission, and low weight. The double panel structure is widely used, such as in the aerospace and automotive industries. Nevertheless, the resonance of the cavity and the poor sound transmission loss at low frequencies limit the double panel's noise control performance. Applying active structural acoustic control to the panels or active noise control to the cavity has been discussed in many papers. In this paper, the resonances of the panels and the cavity are considered simultaneously to further reduce the transmitted noise through an existing double panel structure. A structural-acoustic coupled model is developed to investigate and compare various structural control and cavity control methods. Numerical analysis and real-time control results show that structural control should be applied to both panels. Three types of cavity control sources are presented and compared. The results indicate that the largest noise reduction is obtained with cavity control by loudspeakers modified to operate as incident pressure sources.

Lamb wave band gaps in a double-sided phononic plate

NASA Astrophysics Data System (ADS)

Wang, Peng; Chen, Tian-Ning; Yu, Kun-Peng; Wang, Xiao-Peng

2013-02-01

In this paper, we report on the theoretical investigation of the propagation characteristics of Lamb wave in a phononic crystal structure constituted by a square array of cylindrical stubs deposited on both sides of a thin homogeneous plate. The dispersion relations, the power transmission spectra, and the displacement fields of the eigenmodes are studied by using the finite-element method. We investigate the evolution of band gaps in the double-sided phononic plate with stub height on both sides arranged from an asymmetrical distribution to a symmetrical distribution gradually. Numerical results show that as the double stubs in a unit cell arranged more symmetrically on both sides, band width shifts, new band gaps appear, and the bands become flat due to localized resonant modes which couple with plate modes. Specially, more band gaps and flat bands can be found in the symmetrical system as a result of local resonances of the stubs which interact in a stronger way with the plate modes. Moreover, the symmetrical double-sided plate exhibits lower and smaller band gap than that of the asymmetrical plate. These propagation properties of elastic or acoustic waves in the double-sided plate can potentially be utilized to generate filters, slow the group velocity, low-frequency sound insulation, and design acoustic sensors.

Isotopologue-selective excitation studied via optical-optical double resonance using the E3 Σ1+(63S1) ←A3Π0+(53P1) ←X1Σ0+(51S0) transitions in CdAr and CdKr van der Waals complexes

NASA Astrophysics Data System (ADS)

Urbańczyk, T.; Dudek, J.; Koperski, J.

2018-06-01

A method of experimental selection of molecular isotopologues using optical-optical double resonance (OODR) scheme and supersonic beam source of van der Waals (vdW) complexes is presented. Due to an appropriately large isotopic shift, the proper choice of a wavenumber of a sufficiently narrowband laser in the first transition of OODR scheme can lead to a selective isotopologue excitation to the intermediate state. Thanks to this approach, it is possible to select some of the isotopologues which subsequently give a contribution to laser induced fluorescence (LIF) signal originated from the final state of OODR. In this article, results of tests of the proposed method that employs the E3 Σ1+ ←A3Π0+ ←X1Σ0+ transitions in two vdW complexes, CdKr and CdAr, are presented and analysed.

Study on the ternary mixed ligand complex of palladium(II)-aminophylline-fluorescein sodium by resonance Rayleigh scattering, second-order scattering and frequency doubling scattering spectrum and its analytical application.

PubMed

Chen, Peili; Liu, Shaopu; Liu, Zhongfang; Hu, Xiaoli

2011-01-01

The interaction between palladium(II)-aminophylline and fluorescein sodium was investigated by resonance Rayleigh scattering, second-order scattering and frequency doubling scattering spectrum. In pH 4.4 Britton-Robinson (BR) buffer medium, aminophylline (Ami) reacted with palladium(II) to form chelate cation([Pd(Ami)]2+), which further reacted with fluorescein sodium (FS) to form ternary mixed ligand complex [Pd(Ami)(FS)2]. As a result, resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering spectrum (FDS) were enhanced. The maximum scattering wavelengths of [Pd(Ami)(FS)2] were located at 300 nm (RRS), 650 nm (SOS) and 304 nm (FDS). The scattering intensities were proportional to the Ami concentration in a certain range and the detection limits were 7.3 ng mL(-1) (RRS), 32.9 ng mL(-1) (SOS) and 79.1 ng mL(-1) (FDS), respectively. Based on it, the new simple, rapid, and sensitive scattering methods have been proposed to determine Ami in urine and serum samples. Moreover, the formation mechanism of [Pd(Ami)(FS)2] and the reasons for enhancement of RRS were fully discussed. Crown Copyright © 2010. Published by Elsevier B.V. All rights reserved.

VESUVIO-the double difference inverse geometry spectrometer at ISIS

NASA Astrophysics Data System (ADS)

Mayers, J.; Tomkinson, J.; Abdul-Redah, T.; Stirling, W. G.; Andreani, C.; Senesi, R.; Nardone, M.; Colognesi, D.; Degiorgi, E.

2004-07-01

The VESUVIO spectrometer at the ISIS pulsed neutron source performs inelastic neutron scattering at high-energy and wave vector transfers, employing gold and uranium resonant foils. A factor of two improvement in the instrumental resolution has been achieved by making use of the double filter difference method. Experimental results are presented for measurements on polycrystalline Pb, which indicate that accurate measurements of single-particle momentum distribution n(p) in quantum fluids are now possible at eV energy transfers.

Quantum Transport

DTIC Science & Technology

1993-05-14

Lent 6 I We have studied transmission in quantum waveguides in the presence of resonant cavities. This work was inspired by our previous modeling of the...conductance of resonantly- coupled quantum wire systems. We expected to find qualitatively the same phenomena as in the much studied case of double...transmission peaks does not give the location of the quasi-bound3 states, like for double-barrier resonant tunneling. In current work, we study

Diode-laser-based RIMS measurements of strontium-90

NASA Astrophysics Data System (ADS)

Bushaw, B. A.; Cannon, B. D.

1998-12-01

Double- and triple-resonance excitation schemes for the ionization of strontium are presented. Use of single-mode diode lasers for the resonance excitations provides a high degree of optical isotopic selectivity: with double-resonance, selectivity of >104 for 90Sr against the stable Sr isotopes has been demonstrated. Measurement of lineshapes and stable isotope shifts in the triple-resonance process indicate that optical selectivity should increase to ˜109. When combined with mass spectrometer selectivity this is sufficient for measurement of 90Sr at background environmental levels. Additionally, autoionizing resonances have been investigated for improving ionization efficiency with lower power lasers.

Search for neutrinoless double-electron capture of 156Dy

NASA Astrophysics Data System (ADS)

Finch, S. W.; Tornow, W.

2015-12-01

Background: Multiple large collaborations are currently searching for neutrinoless double-β decay, with the ultimate goal of differentiating the Majorana-Dirac nature of the neutrino. Purpose: Investigate the feasibility of resonant neutrinoless double-electron capture, an experimental alternative to neutrinoless double-β decay. Method: Two clover germanium detectors were operated underground in coincidence to search for the de-excitation γ rays of 156Gd following the neutrinoless double-electron capture of 156Dy. 231.95 d of data were collected at the Kimballton underground research facility with a 231.57 mg enriched 156Dy sample. Results: No counts were seen above background and half-life limits are set at O (1016-1018) yr for the various decay modes of 156Dy. Conclusion: Low background spectra were efficiently collected in the search for neutrinoless double-electron capture of 156Dy, although the low natural abundance and associated lack of large quantities of enriched samples hinders the experimental reach.

Group III Acceptors with Shallow and Deep Levels in Silicon Carbide: ESR and ENDOR Studies

NASA Astrophysics Data System (ADS)

Il'in, I. V.; Uspenskaya, Yu. A.; Kramushchenko, D. D.; Muzafarova, M. V.; Soltamov, V. A.; Mokhov, E. N.; Baranov, P. G.

2018-04-01

Results of investigations of Group III acceptors (B, Al, and Ga) in crystals of silicon carbide using the most informative electron spin resonance and electron nuclear double resonance methods are presented. Structural models of the acceptors with shallow and deep levels are considered. In addition to the data obtained earlier, studies using high-frequency magnetic resonance were obtained, which allowed revealing orthorhombic deviations from the axial symmetry for the deep acceptors; theoretical analysis explains experimentally found shifts of g factors for the deep acceptors arising due to the orthorhombic deviations, which appear probably due to the Jahn-Teller effect.

Nonlocal boundary conditions for corrugated acoustic metasurface with strong near-field interactions

NASA Astrophysics Data System (ADS)

Schwan, Logan; Umnova, Olga; Boutin, Claude; Groby, Jean-Philippe

2018-03-01

The propagation of long-wavelength sound in the presence of a metasurface made by arranging acoustic resonators periodically upon or slightly above an impervious substrate is studied. The method of two-scale asymptotic homogenization is used to derive effective boundary conditions, which account for both the surface corrugation and the low-frequency resonance. This method is applied to periodic arrays of resonators of any shape operating in the long-wavelength regime. The approach relies on the existence of a locally periodic boundary layer developed in the vicinity of the metasurface, where strong near-field interactions of the resonators with each other and with the substrate take place. These local effects give rise to an effective surface admittance supplemented by nonlocal contributions from the simple and double gradients of the pressure at the surface. These phenomena are illustrated for the periodic array of cylindrical Helmholtz resonators with an extended inner duct. Effects of the centre-to-centre spacing and orientation of the resonators' opening on the nonlocality and apparent resonance frequency are studied. The model could be used to design metasurfaces with specific effective boundary conditions required for particular applications.

Gate-tunable resonant tunneling in double bilayer graphene heterostructures.

PubMed

Fallahazad, Babak; Lee, Kayoung; Kang, Sangwoo; Xue, Jiamin; Larentis, Stefano; Corbet, Christopher; Kim, Kyounghwan; Movva, Hema C P; Taniguchi, Takashi; Watanabe, Kenji; Register, Leonard F; Banerjee, Sanjay K; Tutuc, Emanuel

2015-01-14

We demonstrate gate-tunable resonant tunneling and negative differential resistance in the interlayer current-voltage characteristics of rotationally aligned double bilayer graphene heterostructures separated by hexagonal boron nitride (hBN) dielectric. An analysis of the heterostructure band alignment using individual layer densities, along with experimentally determined layer chemical potentials indicates that the resonance occurs when the energy bands of the two bilayer graphene are aligned. We discuss the tunneling resistance dependence on the interlayer hBN thickness, as well as the resonance width dependence on mobility and rotational alignment.

Double resonator cantilever accelerometer

DOEpatents

Koehler, Dale R.

1984-01-01

A digital quartz accelerometer includes a pair of spaced double-ended tuning forks fastened at one end to a base and at the other end through a spacer mass. Transverse movement of the resonator members stresses one and compresses the other, providing a differential frequency output which is indicative of acceleration.

Efficient telecom to visible wavelength conversion in doubly resonant gallium phosphide microdisks

NASA Astrophysics Data System (ADS)

Lake, David P.; Mitchell, Matthew; Jayakumar, Harishankar; dos Santos, Laís Fujii; Curic, Davor; Barclay, Paul E.

2016-01-01

Resonant second harmonic generation between 1550 nm and 775 nm with normalized outside efficiency > 3.8 × 10 - 4 mW - 1 is demonstrated in a gallium phosphide microdisk supporting high-Q modes at visible ( Q ˜ 10 4 ) and infrared ( Q ˜ 10 5 ) wavelengths. The double resonance condition is satisfied for a specific pump power through intracavity photothermal temperature tuning using ˜ 360 μ W of 1550 nm light input to a fiber taper and coupled to a microdisk resonance. Power dependent efficiency consistent with a simple model for thermal tuning of the double resonance condition is observed.

Ensemble-Biased Metadynamics: A Molecular Simulation Method to Sample Experimental Distributions

PubMed Central

Marinelli, Fabrizio; Faraldo-Gómez, José D.

2015-01-01

We introduce an enhanced-sampling method for molecular dynamics (MD) simulations referred to as ensemble-biased metadynamics (EBMetaD). The method biases a conventional MD simulation to sample a molecular ensemble that is consistent with one or more probability distributions known a priori, e.g., experimental intramolecular distance distributions obtained by double electron-electron resonance or other spectroscopic techniques. To this end, EBMetaD adds an adaptive biasing potential throughout the simulation that discourages sampling of configurations inconsistent with the target probability distributions. The bias introduced is the minimum necessary to fulfill the target distributions, i.e., EBMetaD satisfies the maximum-entropy principle. Unlike other methods, EBMetaD does not require multiple simulation replicas or the introduction of Lagrange multipliers, and is therefore computationally efficient and straightforward in practice. We demonstrate the performance and accuracy of the method for a model system as well as for spin-labeled T4 lysozyme in explicit water, and show how EBMetaD reproduces three double electron-electron resonance distance distributions concurrently within a few tens of nanoseconds of simulation time. EBMetaD is integrated in the open-source PLUMED plug-in (www.plumed-code.org), and can be therefore readily used with multiple MD engines. PMID:26083917

31P NMR spectroscopy studies of phospholipid metabolism in human melanoma xenograft lines differing in rate of tumour cell proliferation.

PubMed

Lyng, H; Olsen, D R; Petersen, S B; Rofstad, E K

1995-04-01

The concentration of phospholipid metabolites in tumours has been hypothesized to be related to rate of cell membrane turnover and may reflect rate of cell proliferation. The purpose of the study reported here was to investigate whether 31P NMR resonance ratios involving the phosphomonoester (PME) or phosphodiester (PDE) resonance are correlated to fraction of cells in S-phase or volume-doubling time in experimental tumours. Four human melanoma xenograft lines (BEX-t, HUX-t, SAX-t, WIX-t) were included in the study. The tumours were grown subcutaneously in male BALB/c-nu/nu mice. 31P NMR spectroscopy was performed at a magnetic field strength of 4.7 T. Fraction of cells in S-phase was measured by flow cytometry. Tumour volume-doubling time was determined by Gompertzian analysis of volumetric growth data. BEX-t and SAX-t tumours differed in fraction of cells in S-phase and volume-doubling time, but showed similar 31P NMR resonance ratios. BEX-t and WIX-t tumours showed significantly different 31P NMR resonance ratios but similar fractions of cells in S-phase. The 31P NMR resonance ratios were significantly different for small and large HUX-t tumours even though fraction of cells in S-phase and volume-doubling time did not differ with tumour volume. None of the 31P NMR resonance ratios showed significant increase with increasing fraction of cells in S-phase or significant decrease with increasing tumour volume-doubling time across the four xenograft lines.(ABSTRACT TRUNCATED AT 250 WORDS)

Nature of isomerism of solid isothiourea salts, inhibitors of nitric oxide synthases, as studied by 1H-14N nuclear quadrupole double resonance, X-ray, and density functional theory/quantum theory of atoms in molecules.

PubMed

Latosińska, J N; Latosińska, M; Seliger, J; Žagar, V; Maurin, J K; Kazimierczuk, Z

2012-02-09

Isothioureas, inhibitors of nitric oxide synthases, have been studied experimentally in solid state by nuclear quadrupole double resonance (NQDR) and X-ray methods and theoretically by the quantum theory of atoms in molecules/density functional theory. Resonance frequencies on (14)N have been detected and assigned to particular nitrogen sites in each molecule. The crystal packings of (S)-3,4-dichlorobenzyl-N-methylisothiouronium chloride with the disordered chlorine positions in benzene ring and (S)-butyloisothiouronium bromide have been resolved in X-ray diffraction studies. (14)N NQDR spectra have been found good indicators of isomer type and strength of intra- or intermolecular N-H···X (X = Cl, Br) interactions. From among all salts studied, only for (S)-2,3,4,5,6-pentabromobenzylisothiouronium chloride are both nitrogen sites equivalent, which has been explained by the slow exchange. This unique structural feature can be a key factor in the high biological activity of (S)-2,3,4,5,6-pentabromobenzylisothiouronium salts.

Double Resonances and Spectral Scaling in the Weak Turbulence Theory of Rotating and Stratified Turbulence

NASA Technical Reports Server (NTRS)

Rubinstein, Robert

1999-01-01

In rotating turbulence, stably stratified turbulence, and in rotating stratified turbulence, heuristic arguments concerning the turbulent time scale suggest that the inertial range energy spectrum scales as k(exp -2). From the viewpoint of weak turbulence theory, there are three possibilities which might invalidate these arguments: four-wave interactions could dominate three-wave interactions leading to a modified inertial range energy balance, double resonances could alter the time scale, and the energy flux integral might not converge. It is shown that although double resonances exist in all of these problems, they do not influence overall energy transfer. However, the resonance conditions cause the flux integral for rotating turbulence to diverge logarithmically when evaluated for a k(exp -2) energy spectrum; therefore, this spectrum requires logarithmic corrections. Finally, the role of four-wave interactions is briefly discussed.

Realization of a double-barrier resonant tunneling diode for cavity polaritons.

PubMed

Nguyen, H S; Vishnevsky, D; Sturm, C; Tanese, D; Solnyshkov, D; Galopin, E; Lemaître, A; Sagnes, I; Amo, A; Malpuech, G; Bloch, J

2013-06-07

We report on the realization of a double-barrier resonant tunneling diode for cavity polaritons, by lateral patterning of a one-dimensional cavity. Sharp transmission resonances are demonstrated when sending a polariton flow onto the device. We show that a nonresonant beam can be used as an optical gate and can control the device transmission. Finally, we evidence distortion of the transmission profile when going to the high-density regime, signature of polariton-polariton interactions.

Double resonance calibration of g factor standards: Carbon fibers as a high precision standard

NASA Astrophysics Data System (ADS)

Herb, Konstantin; Tschaggelar, Rene; Denninger, Gert; Jeschke, Gunnar

2018-04-01

The g factor of paramagnetic defects in commercial high performance carbon fibers was determined by a double resonance experiment based on the Overhauser shift due to hyperfine coupled protons. Our carbon fibers exhibit a single, narrow and perfectly Lorentzian shaped ESR line and a g factor slightly higher than gfree with g = 2.002644 =gfree · (1 + 162ppm) with a relative uncertainty of 15ppm . This precisely known g factor and their inertness qualify them as a high precision g factor standard for general purposes. The double resonance experiment for calibration is applicable to other potential standards with a hyperfine interaction averaged by a process with very short correlation time.

Broadband infrared absorbers with stacked double chromium ring resonators

DOE PAGES

Deng, Huixu; Stan, Liliana; Czaplewski, David A.; ...

2017-10-31

A broadband absorber in the infrared wavelength range from 1 μm up to 5 μm is designed and demonstrated with stacked double chromium ring resonators on a reflective chromium mirror. The near-perfect broadband absorption is realized by combining the multilayer impedance match in the short wavelength range and the double plasmonic resonances in the long wavelength range, which is illustrated with an equivalent circuit model for the impedance analysis. The broadband absorber is proved to be angle-insensitive and polarization-independent due to the geometrical symmetry. Lastly, the thermal analysis for heat generation and temperature distributions inside the absorber structure is alsomore » investigated.« less

Broadband infrared absorbers with stacked double chromium ring resonators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deng, Huixu; Stan, Liliana; Czaplewski, David A.

A broadband absorber in the infrared wavelength range from 1 μm up to 5 μm is designed and demonstrated with stacked double chromium ring resonators on a reflective chromium mirror. The near-perfect broadband absorption is realized by combining the multilayer impedance match in the short wavelength range and the double plasmonic resonances in the long wavelength range, which is illustrated with an equivalent circuit model for the impedance analysis. The broadband absorber is proved to be angle-insensitive and polarization-independent due to the geometrical symmetry. Lastly, the thermal analysis for heat generation and temperature distributions inside the absorber structure is alsomore » investigated.« less

Optimal Tikhonov regularization for DEER spectroscopy

NASA Astrophysics Data System (ADS)

Edwards, Thomas H.; Stoll, Stefan

2018-03-01

Tikhonov regularization is the most commonly used method for extracting distance distributions from experimental double electron-electron resonance (DEER) spectroscopy data. This method requires the selection of a regularization parameter, α , and a regularization operator, L. We analyze the performance of a large set of α selection methods and several regularization operators, using a test set of over half a million synthetic noisy DEER traces. These are generated from distance distributions obtained from in silico double labeling of a protein crystal structure of T4 lysozyme with the spin label MTSSL. We compare the methods and operators based on their ability to recover the model distance distributions from the noisy time traces. The results indicate that several α selection methods perform quite well, among them the Akaike information criterion and the generalized cross validation method with either the first- or second-derivative operator. They perform significantly better than currently utilized L-curve methods.

Complex multireference configuration interaction calculations for the K-vacancy Auger states of N{sup q+} (q = 2-5) ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peng, Yi-Geng; Data Center for High Energy Density Physics, Institute of Applied Physics and Computational Mathematics, P.O. Box 8009, Beijing 100088; Wu, Yong, E-mail: wu-yong@iapcm.ac.cn

2016-02-07

K-vacancy Auger states of N{sup q+} (q = 2-5) ions are studied by using the complex multireference single- and double-excitation configuration interaction (CMRD-CI) method. The calculated resonance parameters are in good agreement with the available experimental and theoretical data. It shows that the resonance positions and widths converge quickly with the increase of the atomic basis sets in the CMRD-CI calculations; the standard atomic basis set can be employed to describe the atomic K-vacancy Auger states well. The strong correlations between the valence and core electrons play important roles in accurately determining those resonance parameters, Rydberg electrons contribute negligibly inmore » the calculations. Note that it is the first time that the complex scaling method has been successfully applied for the B-like nitrogen. CMRD-CI is readily extended to treat the resonance states of molecules in the near future.« less

Valence-band structure of the ferromagnetic semiconductor GaMnAs studied by spin-dependent resonant tunneling spectroscopy.

PubMed

Ohya, Shinobu; Muneta, Iriya; Hai, Pham Nam; Tanaka, Masaaki

2010-04-23

The valence-band structure and the Fermi level (E(F)) position of ferromagnetic-semiconductor GaMnAs are quantitatively investigated by electrically detecting the resonant tunneling levels of a GaMnAs quantum well (QW) in double-barrier heterostructures. The resonant level from the heavy-hole first state is clearly observed in the metallic GaMnAs QW, indicating that holes have a high coherency and that E(F) exists in the band gap. Clear enhancement of tunnel magnetoresistance induced by resonant tunneling is demonstrated in these double-barrier heterostructures.

Power enhancement of burst-mode UV pulses using a doubly-resonant optical cavity

DOE PAGES

Rahkman, Abdurahim; Notcutt, Mark; Liu, Yun

2015-11-24

We report a doubly-resonant enhancement cavity (DREC) that can realize a simultaneous enhancement of two incoming laser beams at different wavelengths and different temporal structures. The double-resonance condition is theoretically analyzed and different DREC locking methods are experimentally investigated. Simultaneous locking of a Fabry-Perot cavity to both an infrared (IR, 1064 nm) and its frequency tripled ultraviolet (UV, 355 nm) pulses has been demonstrated by controlling the frequency difference between the two beams with a fiber optic frequency shifter. The DREC technique opens a new paradigm in the applications of optical cavities to power enhancement of burst-mode lasers with arbitrarymore » macropulse width and repetition rate.« less

A Polarization-Dependent Normal Incident Quantum Cascade Detector Enhanced Via Metamaterial Resonators.

PubMed

Wang, Lei; Zhai, Shen-Qiang; Wang, Feng-Jiao; Liu, Jun-Qi; Liu, Shu-Man; Zhuo, Ning; Zhang, Chuan-Jin; Wang, Li-Jun; Liu, Feng-Qi; Wang, Zhan-Guo

2016-12-01

The design, fabrication, and characterization of a polarization-dependent normal incident quantum cascade detector coupled via complementary split-ring metamaterial resonators in the infrared regime are presented. The metamaterial structure is designed through three-dimensional finite-difference time-domain method and fabricated on the top metal contact, which forms a double-metal waveguide together with the metallic ground plane. With normal incidence, significant enhancements of photocurrent response are obtained at the metamaterial resonances compared with the 45° polished edge coupling device. The photocurrent response enhancements exhibit clearly polarization dependence, and the largest response enhancement factor of 165% is gained for the incident light polarized parallel to the split-ring gap.

Pulse Double-Resonance EPR Techniques for the Study of Metallobiomolecules.

PubMed

Cox, Nicholas; Nalepa, Anna; Pandelia, Maria-Eirini; Lubitz, Wolfgang; Savitsky, Anton

2015-01-01

Electron paramagnetic resonance (EPR) spectroscopy exploits an intrinsic property of matter, namely the electron spin and its related magnetic moment. This can be oriented in a magnetic field and thus, in the classical limit, acts like a little bar magnet. Its moment will align either parallel or antiparallel to the field, giving rise to different energies (termed Zeeman splitting). Transitions between these two quantized states can be driven by incident microwave frequency radiation, analogous to NMR experiments, where radiofrequency radiation is used. However, the electron Zeeman interaction alone provides only limited information. Instead, much of the usefulness of EPR is derived from the fact that the electron spin also interacts with its local magnetic environment and thus can be used to probe structure via detection of nearby spins, e.g., NMR-active magnetic nuclei and/or other electron spin(s). The latter is exploited in spin labeling techniques, an exciting new area in the development of noncrystallographic protein structure determination. Although these interactions are often smaller than the linewidth of the EPR experiment, sophisticated pulse EPR methods allow their detection. A number of such techniques are well established today and can be broadly described as double-resonance methods, in which the electron spin is used as a reporter. Below we give a brief description of pulse EPR methods, particularly their implementation at higher magnetic fields, and how to best exploit them for studying metallobiomolecules. © 2015 Elsevier Inc. All rights reserved.

2H{ 19F} REDOR for distance measurements in biological solids using a double resonance spectrometer

NASA Astrophysics Data System (ADS)

Grage, Stephan L.; Watts, Jude A.; Watts, Anthony

2004-01-01

A new approach for distance measurements in biological solids employing 2H{ 19F} rotational echo double resonance was developed and validated on 2H, 19F- D-alanine and an imidazopyridine based inhibitor of the gastric H +/K +-ATPase. The 2H- 19F double resonance experiments presented here were performed without 1H decoupling using a double resonance NMR spectrometer. In this way, it was possible to benefit from the relatively longer distance range of fluorine without the need of specialized fluorine equipment. A distance of 2.5 ± 0.3 Å was measured in the alanine derivative, indicating a gauche conformation of the two labels. In the case of the imidazopyridine compound a lower distance limit of 5.2 Å was determined and is in agreement with an extended conformation of the inhibitor. Several REDOR variants were compared, and their advantages and limitations discussed. Composite fluorine dephasing pulses were found to enhance the frequency bandwidth significantly, and to reduce the dependence of the performance of the experiment on the exact choice of the transmitter frequency.

3μm - 1.6μm Double Resonance Spectroscopy of CH_4

NASA Astrophysics Data System (ADS)

Schwartz, George; Belaas, Erik; Yang, Shaoyue; Lehmann, Kevin

2016-06-01

The Near-IR Spectrum of CH_4 is dense with many overlapping bands that perturb each other by vibrational and ro-vibrational interactions. Assignments of the individual lines are needed in order to simulate the spectrum as a function of pressure and temperature, as needed in the search for CH_4 in extrasolar planets. Both the group at the University College, London^1 and that at the University of Reins^2 have produced theoretical spectra that allows simulation up to the high temperatures expected on ``Hot Jupiters''. The accuracy of these theoretical spectra need to be further tested. Because CH_4 is a light spherical top, assignment of its perturbed spectra is a formable challenge as none of the lines allowed in the rigid rotor approximation have ground vibrational state combination differences. We are using IR-IR double resonance to observe modulation in the strength of near-IR absorption caused by a modulation of a 3 μm OPO beam that is tuned to a particular transition in the C-H stretching fundamental of CH_4. This produces V-type double resonance transitions (which share the lower state with the pump transition), which provides firm assignments for lines normally observed in absorption in the near-IR. We also observe sequential double resonance which reveals transitions that have a known rotational level of the ν_3 fundamental as the lower state and reaches final states in the 9000 cm-1 spectral region. These are states of A, E, F_1 vibrational symmetries which are forbidden in transitions from the ground vibrational state. These 3 level double resonance transitions are Doppler Free and have a linewidth of ˜10 MHz due to a combination of near-IR laser jitter and power broadening of the mid-IR transition. We also observed many 4-level double resonance transitions that we have tentatively assigned as arising from the ν_4 fundamental level. These are distinguished from the 3-level double resonance transitions by they being Doppler broadened and having a large phase shift relative to the intensity modulation. 1. S.N. Yurchenko, PNAS 111 9379-83 (2014); 2. M. Rey, JQSRT 18, 207-220 (2015), PCCP 18, 176-189 (2016)

Double-wavelength overlapping resonance Rayleigh scattering technique for the simultaneous quantitative analysis of three β-adrenergic blockade

NASA Astrophysics Data System (ADS)

Tan, Xuanping; Yang, Jidong; Li, Qin; Yang, Qiong; Shen, Yizhong

2016-05-01

Four simple and accurate spectrophotometric methods were proposed for the simultaneous determination of three β-adrenergic blockade, e.g. atenolol, metoprolol and propranolol. The methods were based on the reaction of the three drugs with erythrosine B (EB) in a Britton-Robinson buffer solution at pH 4.6. EB could combine with the drugs to form three ion-association complexes, which resulted in the resonance Rayleigh scattering (RRS) intensity that is enhanced significantly with new RRS peaks that appeared at 337 nm and 370 nm, respectively. In addition, the fluorescence intensity of EB was also quenched. The enhanced scattering intensities of the two peaks and the fluorescence quenched intensity of EB were proportional to the concentrations of the drugs, respectively. What is more, the RRS intensity overlapped with the double-wavelength of 337 nm and 370 nm (so short for DW-RRS) was also proportional to the drugs concentrations. So, a new method with highly sensitive for simultaneous determination of three bisoprolol drugs was established. Finally, the optimum reaction conditions, influencing factors and spectral enhanced mechanism were investigated. The new DW-RRS method has been applied to simultaneously detect the three β-blockers in fresh serum with satisfactory results.

Double difference method in deep inelastic neutron scattering on the VESUVIO spectrometer

NASA Astrophysics Data System (ADS)

Andreani, C.; Colognesi, D.; Degiorgi, E.; Filabozzi, A.; Nardone, M.; Pace, E.; Pietropaolo, A.; Senesi, R.

2003-02-01

The principles of the Double Difference (DD) method, applied to the neutron spectrometer VESUVIO, are discussed. VESUVIO, an inverse geometry spectrometer operating at the ISIS pulsed neutron source in the eV energy region, has been specifically designed to measure the single particle dynamical properties in condensed matter. The width of the nuclear resonance of the absorbing filter, used for the neutron energy analysis, provides the most important contribution to the energy resolution of the inverse geometry instruments. In this paper, the DD method, which is based on a linear combination of two measurements recorded with filter foils of the same resonance material but of different thickness, is shown to improve significantly the instrumental energy resolution, as compared with the Single Difference (SD) method. The asymptotic response functions, derived through Monte-Carlo simulations for polycrystalline Pb and ZrH 2 samples, are analysed in both DD and SD methods, and compared with the experimental ones for Pb sample. The response functions have been modelled for two distinct experimental configurations of the VESUVIO spectrometer, employing 6Li-glass neutron detectors and NaI γ detectors revealing the γ-ray cascade from the ( n,γ) reaction, respectively. The DD method appears to be an effective experimental procedure for Deep Inelastic Neutron Scattering measurements on VESUVIO spectrometer, since it reduces the experimental resolution of the instrument in both 6Li-glass neutron detector and γ detector configurations.

Nonlinear theory of the narrow-band generation and detection of terahertz radiation in resonant tunneling heterostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kapaev, V. V., E-mail: kapaev@lebedev.ru

The nonlinear regime of high-frequency response for resonant tunneling structures in a time-periodic electric field has been investigated using a technique for solving the time-dependent Schrödinger equation based on a Floquet mode expansion of the wave functions. The dependences of current harmonic amplitudes on ac signal amplitude have been calculated and the limiting values of the generated field have been determined for singleand double-well resonant tunneling structures. The dynamic Stark effect is shown to play an important role in the formation of response. It leads to a quadratic (in ac field amplitude) shift in the positions of resonances E{sub r}more » in single-well structures and in double-well ones in the nonresonant case and to a splitting at resonance hν ≈ E{sub r2}–E{sub r1} (ν is the signal frequency, E{sub r1} and E{sub r2} are the energies of the size-quantization levels) in double-well structures proportional to the ac signal amplitude. The phenomenon of ac signal detection by resonant tunneling structures has been investigated. The effect of resonant direct-current amplification in double-well structures has been detected at a signal frequency satisfying the condition hν ≈ E{sub r2}–E{sub r1}. In asymmetric systems, detection is shown to be possible in the absence of a dc bias, which allows zero-biased detectors based on them to be created.« less

The Double Opposing Z-Plasty Plus or Minus Buccal Flap Approach for Repair of Cleft Palate: A Review of 505 Consecutive Cases.

PubMed

Mann, Robert J; Martin, Matthew D; Eichhorn, Mitchell G; Neaman, Keith C; Sierzant, Charles G; Polley, John W; Girotto, John A

2017-03-01

Standard methods of cleft palate repair rely on existing palatal tissue to achieve closure. These procedures often require relaxing incisions, causing scars and growth restriction, and may result in insufficient palatal length and suboptimal positioning of the velar musculature. The Furlow double opposing Z-plasty improves palatal length and repositions the velar musculature; however, relaxing incisions may still be needed. The addition of buccal flaps to the Furlow repair obviates the need for relaxing incisions and allows the Furlow repair to be used in wide clefts. A retrospective review was performed on 505 patients; all patients were treated with the double opposing Z-plasty plus or minus buccal flap approach. Outcomes included nasal resonance, secondary speech surgery, and postoperative complications. A comparison was made between patients treated with double opposing Z-plasty alone and those treated with double opposing Z-plasty plus buccal flaps. The average nasal resonance score was 1.38 and was equivalent in both the double opposing Z-plasty alone and with buccal flap groups, despite significantly more wide clefts in the buccal flap group (56 percent versus 8 percent). The secondary surgery rate for velopharyngeal insufficiency was 6.6 percent and the fistula rate was 6.1 percent. The large fistula rate (>2 mm) was 2.7 percent. The double opposing Z-plasty plus or minus buccal flap approach is a useful alternative to standard palate repairs. Speech outcomes were excellent, even in wider clefts, and postoperative complications were minimal. Buccal flaps allow the benefits of the Furlow repair to be applied to any size cleft, without the need for relaxing incisions. Therapeutic, III.

Optically controlled resonant tunneling in a double-barrier diode

NASA Astrophysics Data System (ADS)

Kan, S. C.; Wu, S.; Sanders, S.; Griffel, G.; Yariv, A.

1991-03-01

The resonant tunneling effect is optically enhanced in a GaAs/GaAlAs double-barrier structure that has partial lateral current confinement. The peak current increases and the valley current decreases simultaneously when the device surface is illuminated, due to the increased conductivity of the top layer of the structure. The effect of the lateral current confinement on the current-voltage characteristic of a double-barrier resonant tunneling structure was also studied. With increased lateral current confinement, the peak and valley current decrease at a different rate such that the current peak-to-valley ratio increases up to three times. The experimental results are explained by solving the electrostatic potential distribution in the structure using a simple three-layer model.

Non-iterative triple excitations in equation-of-motion coupled-cluster theory for electron attachment with applications to bound and temporary anions.

PubMed

Jagau, Thomas-C

2018-01-14

The impact of residual electron correlation beyond the equation-of-motion coupled-cluster singles and doubles (EOM-CCSD) approximation on positions and widths of electronic resonances is investigated. To establish a method that accomplishes this task in an economical manner, several approaches proposed for the approximate treatment of triple excitations are reviewed with respect to their performance in the electron attachment (EA) variant of EOM-CC theory. The recently introduced EOM-CCSD(T)(a)* method [D. A. Matthews and J. F. Stanton, J. Chem. Phys. 145, 124102 (2016)], which includes non-iterative corrections to the reference and the target states, reliably reproduces vertical attachment energies from EOM-EA-CC calculations with single, double, and full triple excitations in contrast to schemes in which non-iterative corrections are applied only to the target states. Applications of EOM-EA-CCSD(T)(a)* augmented by a complex absorbing potential (CAP) to several temporary anions illustrate that shape resonances are well described by EOM-EA-CCSD, but that residual electron correlation often makes a non-negligible impact on their positions and widths. The positions of Feshbach resonances, on the other hand, are significantly improved when going from CAP-EOM-EA-CCSD to CAP-EOM-EA-CCSD(T)(a)*, but the correct energetic order of the relevant electronic states is still not achieved.

Non-iterative triple excitations in equation-of-motion coupled-cluster theory for electron attachment with applications to bound and temporary anions

NASA Astrophysics Data System (ADS)

Jagau, Thomas-C.

2018-01-01

The impact of residual electron correlation beyond the equation-of-motion coupled-cluster singles and doubles (EOM-CCSD) approximation on positions and widths of electronic resonances is investigated. To establish a method that accomplishes this task in an economical manner, several approaches proposed for the approximate treatment of triple excitations are reviewed with respect to their performance in the electron attachment (EA) variant of EOM-CC theory. The recently introduced EOM-CCSD(T)(a)* method [D. A. Matthews and J. F. Stanton, J. Chem. Phys. 145, 124102 (2016)], which includes non-iterative corrections to the reference and the target states, reliably reproduces vertical attachment energies from EOM-EA-CC calculations with single, double, and full triple excitations in contrast to schemes in which non-iterative corrections are applied only to the target states. Applications of EOM-EA-CCSD(T)(a)* augmented by a complex absorbing potential (CAP) to several temporary anions illustrate that shape resonances are well described by EOM-EA-CCSD, but that residual electron correlation often makes a non-negligible impact on their positions and widths. The positions of Feshbach resonances, on the other hand, are significantly improved when going from CAP-EOM-EA-CCSD to CAP-EOM-EA-CCSD(T)(a)*, but the correct energetic order of the relevant electronic states is still not achieved.

In Vivo Application of Proton-Electron Double-Resonance Imaging

PubMed Central

Kishimoto, Shun; Krishna, Murali C.; Khramtsov, Valery V.; Utsumi, Hideo

2018-01-01

Abstract Significance: Proton-electron double-resonance imaging (PEDRI) employs electron paramagnetic resonance irradiation with low-field magnetic resonance imaging so that the electron spin polarization is transferred to nearby protons, resulting in higher signals. PEDRI provides information about free radical distribution and, indirectly, about the local microenvironment such as partial pressure of oxygen (pO2), tissue permeability, redox status, and acid-base balance. Recent Advances: Local acid-base balance can be imaged by exploiting the different resonance frequency of radical probes between R and RH+ forms. Redox status can also be imaged by using the loss of radical-related signal after reduction. These methods require optimized radical probes and pulse sequences. Critical Issues: High-power radio frequency irradiation is needed for optimum signal enhancement, which may be harmful to living tissue by unwanted heat deposition. Free radical probes differ depending on the purpose of PEDRI. Some probes are less effective for enhancing signal than others, which can reduce image quality. It is so far not possible to image endogenous radicals by PEDRI because low concentrations and broad line widths of the radicals lead to negligible signal enhancement. Future Directions: PEDRI has similarities with electron paramagnetic resonance imaging (EPRI) because both techniques observe the EPR signal, directly in the case of EPRI and indirectly with PEDRI. PEDRI provides information that is vital to research on homeostasis, development of diseases, or treatment responses in vivo. It is expected that the development of new EPR techniques will give insights into novel PEDRI applications and vice versa. Antioxid. Redox Signal. 28, 1345–1364. PMID:28990406

A study on stimulation of DC high voltage power of LCC series parallel resonant in projectile velocity measurement system

NASA Astrophysics Data System (ADS)

Lu, Dong-dong; Gu, Jin-liang; Luo, Hong-e.; Xia, Yan

2017-10-01

According to specific requirements of the X-ray machine system for measuring velocity of outfield projectile, a DC high voltage power supply system is designed for the high voltage or the smaller current. The system comprises: a series resonant circuit is selected as a full-bridge inverter circuit; a high-frequency zero-current soft switching of a high-voltage power supply is realized by PWM output by STM32; a nanocrystalline alloy transformer is chosen as a high-frequency booster transformer; and the related parameters of an LCC series-parallel resonant are determined according to the preset parameters of the transformer. The concrete method includes: a LCC series parallel resonant circuit and a voltage doubling circuit are stimulated by using MULTISM and MATLAB; selecting an optimal solution and an optimal parameter of all parts after stimulation analysis; and finally verifying the correctness of the parameter by stimulation of the whole system. Through stimulation analysis, the output voltage of the series-parallel resonant circuit gets to 10KV in 28s: then passing through the voltage doubling circuit, the output voltage gets to 120KV in one hour. According to the system, the wave range of the output voltage is so small as to provide the stable X-ray supply for the X-ray machine for measuring velocity of outfield projectile. It is fast in charging and high in efficiency.

Effect of metal shielding on a wireless power transfer system

NASA Astrophysics Data System (ADS)

Li, Jiacheng; Huang, Xueliang; Chen, Chen; Tan, Linlin; Wang, Wei; Guo, Jinpeng

2017-05-01

In this paper, the effect of non-ferromagnetic metal shielding (NFMS) material on the resonator of wireless power transfer (WPT) is studied by modeling, simulation and experimental analysis. And, the effect of NFMS material on the power transfer efficiency (PTE) of WPT systems is investigated by circuit model. Meanwhile, the effect of ferromagnetic metal shielding material on the PTE of WPT systems is analyzed through simulation. A double layer metal shield structure is designed. Experimental results demonstrate that by applying the novel double layer metal shielding method, the system PTE increases significantly while the electromagnetic field of WPT systems declines dramatically.

The double polarization program of CBELSA/TAPS

NASA Astrophysics Data System (ADS)

Thiel, Annika

2014-06-01

The excitation spectrum of the proton consists of resonances with substancial width which are often strongly overlapping and are therefore difficult to disentangle. To determine the exact contributions and identify these resonances, a partial wave analysis solution has to be found. For a complete experiment, which leads to an unambiguous solution, several single and double polarization observables are needed. With the Crystal Barrel/TAPS experiment at ELSA, the measurement of double polarization observables in different reactions is possible by using a circularly or linearly polarized photon beam on a transversely or longitudinally polarized butanol target.

Quantum ratchet effect in a time non-uniform double-kicked model

NASA Astrophysics Data System (ADS)

Chen, Lei; Wang, Zhen-Yu; Hui, Wu; Chu, Cheng-Yu; Chai, Ji-Min; Xiao, Jin; Zhao, Yu; Ma, Jin-Xiang

2017-07-01

The quantum ratchet effect means that the directed transport emerges in a quantum system without a net force. The delta-kicked model is a quantum Hamiltonian model for the quantum ratchet effect. This paper investigates the quantum ratchet effect based on a time non-uniform double-kicked model, in which two flashing potentials alternately act on a particle with a homogeneous initial state of zero momentum, while the intervals between adjacent actions are not equal. The evolution equation of the state of the particle is derived from its Schrödinger equation, and the numerical method to solve the evolution equation is pointed out. The results show that quantum resonances can induce the ratchet effect in this time non-uniform double-kicked model under certain conditions; some quantum resonances, which cannot induce the ratchet effect in previous models, can induce the ratchet effect in this model, and the strengths of the ratchet effect in this model are stronger than those in previous models under certain conditions. These results enrich people’s understanding of the delta-kicked model, and provides a new optional scheme to control the quantum transport of cold atoms in experiment.

Double resonance calibration of g factor standards: Carbon fibers as a high precision standard.

PubMed

Herb, Konstantin; Tschaggelar, Rene; Denninger, Gert; Jeschke, Gunnar

2018-04-01

The g factor of paramagnetic defects in commercial high performance carbon fibers was determined by a double resonance experiment based on the Overhauser shift due to hyperfine coupled protons. Our carbon fibers exhibit a single, narrow and perfectly Lorentzian shaped ESR line and a g factor slightly higher than g free with g=2.002644=g free ·(1+162ppm) with a relative uncertainty of 15ppm. This precisely known g factor and their inertness qualify them as a high precision g factor standard for general purposes. The double resonance experiment for calibration is applicable to other potential standards with a hyperfine interaction averaged by a process with very short correlation time. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Decoupling capabilities of split-loop resonator structure for 7 Tesla MRI surface array coils

NASA Astrophysics Data System (ADS)

Hurshkainen, A.; Kurdjumov, S.; Simovski, C.; Glybovski, S.; Melchakova, I.; van den Berg, C. A. T.; Raaijmakers, A.; Belov, P.

2017-09-01

In this work we studied electromagnetic properties of one-dimentional periodic structures composed of split-loop res-onators (SLRs) and investigated their capabilities in decoupling of two dipole antennas for full-body magnetic resonance imaging (MRI). Two different finite structures comprising a single-SLR and a double-SLR constitutive elements were studied. Numerical simulations of the structures were performed to evaluate their decoupling capabilities. As it was demonstrated two dipole antennas equipped with either a single or a double-SLR structure exhibit high isolation even for an electrically short distance between the dipoles. Double-SLR structure while dramatically improving isolation of the dipoles keeps the field created by each of the decoupled dipoles comparable with one of a single dipole inside the target area.

First measurement of the double spin asymmetry in (-->)e(-->)p-->e(prime)pi(+)n in the resonance region.

PubMed

De Vita, R; Anghinolfi, M; Burkert, V D; Dodge, G E; Minehart, R; Taiuti, M; Weller, H; Adams, G; Amaryan, M J; Anciant, E; Armstrong, D S; Asavapibhop, B; Asryan, G; Audit, G; Auger, T; Avakian, H; Bagdasaryan, H; Ball, J P; Barrow, S; Battaglieri, M; Beard, K; Bektasoglu, M; Bianchi, N; Biselli, A S; Boiarinov, S; Bonner, B E; Bosted, P; Bouchigny, S; Branford, D; Brooks, W K; Bueltmann, S; Calarco, J R; Capitani, G P; Carman, D S; Carnahan, B; Cazes, A; Ciciani, L; Cole, P L; Coleman, A; Connelly, J; Cords, D; Corvisiero, P; Crabb, D; Crannell, H; Cummings, J P; De Sanctis, E; Degtyarenko, P V; Demirchyan, R; Denizli, H; Dennis, L; Dharmawardane, K V; Dhuga, K S; Djalali, C; Doughty, D; Dragovitsch, P; Dugger, M; Dytman, S; Eckhause, M; Egiyan, H; Egiyan, K S; Elouadrhiri, L; Empl, A; Farhi, L; Fatemi, R; Feuerbach, R J; Ficenec, J; Forest, T A; Frolov, V; Funsten, H; Gaff, S J; Gai, M; Garçon, M; Gavalian, G; Gilad, S; Gilfoyle, G P; Giovanetti, K L; Girard, P; Golovatch, E; Griffioen, K; Guidal, M; Guillo, M; Gyurjyan, V; Hadjidakis, C; Hancock, D; Hardie, J; Heddle, D; Heimberg, P; Hersman, F W; Hicks, K; Hicks, R S; Holtrop, M; Hu, J; Hyde-Wright, C E; Ishkanov, B S; Ito, M M; Jenkins, D; Joo, K; Kelley, J H; Kellie, J D; Khandaker, M; Kim, K Y; Kim, K; Kim, W; Klein, A; Klein, F J; Klusman, M; Kossov, M; Kramer, L H; Kuang, Y; Kuhn, S E; Lachniet, J; Laget, J M; Lawrence, D; Li, Ji; Livingston, K; Longhi, A; Loukachine, K; Lucas, M; Major, W; Manak, J J; Marchand, C; McAleer, S; McCarthy, J; McNabb, J W C; Mecking, B A; Mestayer, M D; Meyer, C A; Mikhailov, K; Mirazita, M; Miskimen, R; Mokeev, V; Muccifora, V; Mueller, J; Mutchler, G S; Napolitano, J; Nelson, S O; Niculescu, G; Niculescu, I; Niczyporuk, B B; Niyazov, R A; Opper, A K; O'Rielly, G V; Osipenko, M; Park, K; Pasyuk, E; Peterson, G; Philips, S A; Pivnyuk, N; Pocanic, D; Pogorelko, O; Polli, E; Pozdniakov, S; Preedom, B M; Price, J W; Prok, Y; Protopopescu, D; Qin, L M; Raue, B A; Reolon, A R; Riccardi, G; Ricco, G; Ripani, M; Ritchie, B G; Rock, S; Ronchetti, F; Rossi, P; Rowntree, D; Rubin, P D; Sabatié, F; Sabourov, K; Salgado, C; Sapunenko, V; Sargsyan, M; Schumacher, R A; Serov, V S; Shafi, A; Sharabian, Y G; Shaw, J; Skabelin, A V; Smith, E S; Smith, T; Smith, L C; Sober, D I; Sorrell, L; Spraker, M; Stavinsky, A; Stepanyan, S; Stoler, P; Strakovsky, I I; Taylor, S; Tedeschi, D J; Thompson, R; Todor, L; Ungaro, M; Vineyard, M F; Vlassov, A V; Wang, K; Weinstein, L B; Weisberg, A; Weygand, D P; Whisnant, C S; Wolin, E; Yegneswaran, A; Yun, J; Zhang, B; Zhao, J; Zhou, Z

2002-02-25

The double spin asymmetry in the (-->)e(-->)p --> e(prime)pi(+)n reaction has been measured for the first time in the resonance region for four-momentum transfer Q2 = 0.35-1.5 GeV(2). Data were taken at Jefferson Lab with the CLAS detector using a 2.6 GeV polarized electron beam incident on a polarized solid NH3 target. Comparison with predictions of phenomenological models shows strong sensitivity to resonance contributions. Helicity-1/2 transitions are found to be dominant in the second and third resonance regions. The measured asymmetry is consistent with a faster rise with Q(2) of the helicity asymmetry A1 for the F(15)(1680) resonance than expected from the analysis of the unpolarized data.

Noninvasive Classification of Hepatic Fibrosis Based on Texture Parameters From Double Contrast-Enhanced Magnetic Resonance Images

PubMed Central

Bahl, Gautam; Cruite, Irene; Wolfson, Tanya; Gamst, Anthony C.; Collins, Julie M.; Chavez, Alyssa D.; Barakat, Fatma; Hassanein, Tarek; Sirlin, Claude B.

2016-01-01

Purpose To demonstrate a proof of concept that quantitative texture feature analysis of double contrast-enhanced magnetic resonance imaging (MRI) can classify fibrosis noninvasively, using histology as a reference standard. Materials and Methods A Health Insurance Portability and Accountability Act (HIPAA)-compliant Institutional Review Board (IRB)-approved retrospective study of 68 patients with diffuse liver disease was performed at a tertiary liver center. All patients underwent double contrast-enhanced MRI, with histopathology-based staging of fibrosis obtained within 12 months of imaging. The MaZda software program was used to compute 279 texture parameters for each image. A statistical regularization technique, generalized linear model (GLM)-path, was used to develop a model based on texture features for dichotomous classification of fibrosis category (F ≤2 vs. F ≥3) of the 68 patients, with histology as the reference standard. The model's performance was assessed and cross-validated. There was no additional validation performed on an independent cohort. Results Cross-validated sensitivity, specificity, and total accuracy of the texture feature model in classifying fibrosis were 91.9%, 83.9%, and 88.2%, respectively. Conclusion This study shows proof of concept that accurate, noninvasive classification of liver fibrosis is possible by applying quantitative texture analysis to double contrast-enhanced MRI. Further studies are needed in independent cohorts of subjects. PMID:22851409

Pion single and double charge exchange in the resonance region: Dynamical corrections

NASA Astrophysics Data System (ADS)

Johnson, Mikkel B.; Siciliano, E. R.

1983-04-01

We consider pion-nucleus elastic scattering and single- and double-charge-exchange scattering to isobaric analog states near the (3,3) resonance within an isospin invariant framework. We extend previous theories by introducing terms into the optical potential U that are quadratic in density and consistent with isospin invariance of the strong interaction. We study the sensitivity of single and double charge exchange angular distributions to parameters of the second-order potential both numerically, by integrating the Klein-Gordon equation, and analytically, by using semiclassical approximations that explicate the dependence of the exact numerical results to the parameters of U. The magnitude and shape of double charge exchange angular distributions are more sensitive to the isotensor term in U than has been hitherto appreciated. An examination of recent experimental data shows that puzzles in the shape of the 18O(π+, π-)18Ne angular distribution at 164 MeV and in the A dependence of the forward double charge exchange scattering on 18O, 26Mg, 42Ca, and 48Ca at the same energy may be resolved by adding an isotensor term in U. NUCLEAR REACTIONS Scattering theory for elastic, single-, and double-charge-exchange scattering to IAS in the region of the P33 resonance. Second-order effects on charge-exchange calculations of σ(A, θ).

Add-drop double bus microresonator array local oscillators for sharp multiple Fano resonance engineering

NASA Astrophysics Data System (ADS)

Li, Jiahua; Qu, Ye; Wu, Ying

2018-03-01

Asymmetric resonances are currently the subject of considerable research efforts in photonic nanostructures. Here we propose a feasible method to achieve multiple Fano resonances and their control in an optical compound system consisting of an array of on-chip microresonators without mutual coupling and two parallel fiber waveguides side-coupled to the microresonator array by means of a local oscillator. We derive analytical and transparent expressions for the power transmission function summing over the two light transporting paths within the framework of quantum optics. It is clearly shown that introducing the local oscillator as an additional light propagating path plays an important role in the formation of narrow and multiple Fano resonance lineshapes. The power transmission spectrum through the combination of both the microresonator array and the local oscillator is very sensitive to the system parameters, for example, the intrinsic decay rate of the resonator, the phase shift factor of the local oscillator, the transmission coefficient of the fiber beam splitter, and the total number of the microresonators. Through detailed analysis, we identify the optimums for generating Fano resonance lineshapes. Also, we assess the experimental feasibility of the scheme using currently available technology. The proposed method is relatively straightforward as it requires only one local oscillator as one interferometer arm and it is mostly fiber-based. We believe that our work will help to understand and improve multiple Fano resonance engineering.

Bio-sensing based on plasmon-coupling caused by rotated sub-micrometer gratings in metal-dielectric interfacial layers

NASA Astrophysics Data System (ADS)

Csete, M.; Sipos, Á.; Szalai, A.; Mathesz, A.; Deli, M. A.; Veszelka, Sz.; Schmatulla, A.; Kőházi-Kis, A.; Osvay, K.; Marti, O.; Bor, Zs.

2007-09-01

Novel plasmonic sensor chips are prepared by generating sub-micrometer periodic patterns in the interfacial layers of bimetal-polymer films via master-grating based interference method. Poly-carbonate films spin-coated onto vacuum evaporated silver-gold bimetallic layers are irradiated by the two interfering UV beams of a Nd:YAG laser. It is proven by pulsed force mode AFM that periodic adhesion pattern corresponds to the surface relief gratings, consisting of sub-micrometer droplet arrays and continuous polymer stripes, induced by p- and s-polarized beams, respectively. The characteristic periods are the same, but more complex and larger amplitude adhesion modulation is detectable on the droplet arrays. The polar and azimuthal angle dependence of the resonance characteristic of plasmons is studied by combining the prism- and grating-coupling methods in a modified Kretschmann arrangement, illuminating the structured metal-polymer interface by a frequency doubled Nd:YAG laser through a semi-cylinder. It is proven that the grating-coupling results in double-peaked plasmon resonance curves on both of the droplet arrays and line gratings, when the grooves are rotated to an appropriate azimuthal angle, and the modulation amplitude of the structure is sufficiently large. Streptavidin seeding is performed to demonstrate that small amount of protein can be detected monitoring the shift of the secondary resonance minima. The available high concentration sensitivity is explained by the promotion of protein adherence in the structure's valleys due to the enhanced adhesion. The line-shaped polymer gratings resulting in narrow resonance peaks are utilized to demonstrate the effect of therapeutic molecules on Amyloid-Β peptide, a pathogenic factor in Alzheimer disease.

Multiple-Barrier Resonant Tunneling Structures for Application in a Microwave Generator Stabilized by Microstrip Resonator

DTIC Science & Technology

2000-06-23

conductivity ( NDC ) effects in double barrier resonant tunneling structures (DBRTS) prove the extremely fast frequency response of charge transport (less...UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADP013131 TITLE: Multiple-Barrier Resonant Tunneling Structures for...Institute Multiple-barrier resonant tunneling structures for application in a microwave generator stabilized by microstrip resonator S. V. Evstigneev, A. L

Internal resonance and low frequency vibration energy harvesting

NASA Astrophysics Data System (ADS)

Yang, Wei; Towfighian, Shahrzad

2017-09-01

A nonlinear vibration energy harvester with internal resonance is presented. The proposed harvester consists of two cantilevers, each with a permanent magnet on its tip. One cantilever has a piezoelectric layer at its base. When magnetic force is applied this two degrees-of-freedom nonlinear vibration system shows the internal resonance phenomenon that broadens the frequency bandwidth compared to a linear system. Three coupled partial differential equations are obtained to predict the dynamic behavior of the nonlinear energy harvester. The perturbation method of multiple scales is used to solve equations. Results from experiments done at different vibration levels with varying distances between the magnets validate the mathematical model. Experiments and simulations show the design outperforms the linear system by doubling the frequency bandwidth. Output voltage for frequency response is studied for different system parameters. The optimal load resistance is obtained for the maximum power in the internal resonance case. The results demonstrate that a design combining internal resonance and magnetic nonlinearity improves the efficiency of energy harvesting.

Evaluation of the horizontal-to-vertical spectral ratio (HVSR) seismic method to determine sediment thickness in the vicinity of the South Well Field, Franklin County, OH

USGS Publications Warehouse

Haefner, Ralph J.; Sheets, Rodney A.; Andrews, Robert E.

2011-01-01

The horizontal-to-vertical spectral ratio (HVSR) seismic method involves analyzing measurements of ambient seismic noise in three dimensions to determine the fundamental site resonance frequency. Resonance is excited by the interaction of surface waves (Rayleigh and Love) and body waves (vertically incident shear) with the high-contrast aconstic impedance boundary at the bedrock-sediment interface. Measurements were made to determine the method's utility for estimating thickness of unconsolidated glacial sediments at 18 locations at the South Well Field, Franklin County, OH, and at six locations in Pickaway County where sediment thickness was already known. Measurements also were made near a high-capacity production well (with pumping on and off) and near a highway and a limestone quarry to examine changes in resonance frequencies over a 20-hour period. Although the regression relation for resonance frequency and sediment thickness had a relatively low [r.sup.2] (0.322), estimates of sediment thickness were, on average, within 14 percent of known thicknesses. Resonance frequencies for pumping on and pumping off were identical, although the amplitude of the peak was nearly double under pumping conditions. Resonance frequency for the 20-hour period did not change, but the amplitude of the peak changed considerably, with a maximum amplitude in the early afternoon and minimum in the very early morning hours. Clay layers within unconsolidated sediments may influence resonance frequency and the resulting regression equation, resulting in underestimation of sediment thickness; however, despite this and other complicating factors, hydrogeologists should consider this method when thickness data are needed for unconsolidated sediments.

Evaluation of the horizontal-to-vertical spectral ratio (HVSR) seismic method to determine sediment thickness in the vicinity of the south well field, Franklin county, OH

USGS Publications Warehouse

Haefner, R.J.; Sheets, R.A.; Andrews, R.E.

2010-01-01

The horizontal-to-vertical spectral ratio (HVSR) seismic method involves analyzing measurements of ambient seismic noise in three dimensions to determine the fundamental site resonance frequency. Resonance is excited by the interaction of surface waves (Rayleigh and Love) and body waves (vertically incident shear) with the high-contrast acoustic impedance boundary at the bedrock-sediment interface. Measurements were made to determine the method's utility for estimating thickness of unconsolidated glacial sediments at 18 locations at the South Well Field, Franklin County, OH, and at six locations in Pickaway County where sediment thickness was already known. Measurements also were made near a high-capacity production well (with pumping on and off ) and near a highway and a limestone quarry to examine changes in resonance frequencies over a 20-hour period. Although the regression relation for resonance frequency and sediment thickness had a relatively low r 2(0.322), estimates of sediment thickness were, on average, within 14 percent of known thicknesses. Resonance frequencies for pumping on and pumping off were identical, although the amplitude of the peak was nearly double under pumping conditions. Resonance frequency for the 20-hour period did not change, but the amplitude of the peak changed considerably, with a maximum amplitude in the early afternoon and minimum in the very early morning hours. Clay layers within unconsolidated sediments may influence resonance frequency and the resulting regression equation, resulting in underestimation of sediment thickness; however, despite this and other complicating factors, hydrogeologists should consider this method when thickness data are needed for unconsolidated sediments. ?? 2011 by The Ohio Academy of Science. All Rights Reserved.

Enhancing sound absorption and transmission through flexible multi-layer micro-perforated structures.

PubMed

Bravo, Teresa; Maury, Cédric; Pinhède, Cédric

2013-11-01

Theoretical and experimental results are presented into the sound absorption and transmission properties of multi-layer structures made up of thin micro-perforated panels (ML-MPPs). The objective is to improve both the absorption and insulation performances of ML-MPPs through impedance boundary optimization. A fully coupled modal formulation is introduced that predicts the effect of the structural resonances onto the normal incidence absorption coefficient and transmission loss of ML-MPPs. This model is assessed against standing wave tube measurements and simulations based on impedance translation method for two double-layer MPP configurations of relevance in building acoustics and aeronautics. Optimal impedance relationships are proposed that ensure simultaneous maximization of both the absorption and the transmission loss under normal incidence. Exhaustive optimization of the double-layer MPPs is performed to assess the absorption and/or transmission performances with respect to the impedance criterion. It is investigated how the panel volumetric resonances modify the excess dissipation that can be achieved from non-modal optimization of ML-MPPs.

Scattering of waves by impurities in precompressed granular chains.

PubMed

Martínez, Alejandro J; Yasuda, Hiromi; Kim, Eunho; Kevrekidis, P G; Porter, Mason A; Yang, Jinkyu

2016-05-01

We study scattering of waves by impurities in strongly precompressed granular chains. We explore the linear scattering of plane waves and identify a closed-form expression for the reflection and transmission coefficients for the scattering of the waves from both a single impurity and a double impurity. For single-impurity chains, we show that, within the transmission band of the host granular chain, high-frequency waves are strongly attenuated (such that the transmission coefficient vanishes as the wavenumber k→±π), whereas low-frequency waves are well-transmitted through the impurity. For double-impurity chains, we identify a resonance-enabling full transmission at a particular frequency-in a manner that is analogous to the Ramsauer-Townsend (RT) resonance from quantum physics. We also demonstrate that one can tune the frequency of the RT resonance to any value in the pass band of the host chain. We corroborate our theoretical predictions both numerically and experimentally, and we directly observe almost complete transmission for frequencies close to the RT resonance frequency. Finally, we show how this RT resonance can lead to the existence of reflectionless modes in granular chains (including disordered ones) with multiple double impurities.

Sensitivity enhancement in whole-body natural abundance 13C spectroscopy using 13C/1H double-resonance techniques at 4 tesla.

PubMed

Bomsdorf, H; Röschmann, P; Wieland, J

1991-11-01

In vivo 13C spectroscopy experiments were performed using a whole-body MR system at a static field of 4 T. The main goal of the investigations was to evaluate the sensitivity increase achievable by means of 13C/1H double-resonance techniques at 4 T. Spectra from subcutaneous fat as well as muscle glycogen from the lower leg were acquired using frequency selective proton decoupling and the polarization transfer method SINEPT. With respect to measurements on subcutaneous fat, polarization transfer turned out to be more efficient than selective decoupling. About a fourfold enhancement in spectral peak intensity for the C = C line doublet of the unsaturated fatty acid chain was obtained. Combining polarization transfer with decoupling yielded a factor of 6 in signal amplitude. In contrast to that, the signal enhancement observed in measurements on the glycogen C-1 resonance was only around twofold. The lower efficiency is explained by fast T2 relaxation of the proton transition. A T2 value of about 3 ms was derived from the experimental data. Acquisition times as low as 3 min were realized for normal level glycogen in human calf muscle, enabling a time resolution adequate for dynamic studies on muscle glycogen depletion. Aspects of RF power absorption in tissue and the generally higher efficiency make polarization transfer methods preferable to selective decoupling in whole-body 13C spectroscopy at 4 T.

Effects of resonant magnetic perturbation on the triggering and the evolution of double-tearing mode

NASA Astrophysics Data System (ADS)

Wang, L.; Lin, W. B.; Wang, X. Q.

2018-02-01

The effects of resonant magnetic perturbation on the triggering and the evolution of the double-tearing mode are investigated by using nonlinear magnetohydrodynamics simulations in a slab geometry. It is found that the double-tearing mode can be destabilized by boundary magnetic perturbation. Moreover, the mode has three typical development stages before it reaches saturation: the linear stable stage, the linear-growth stage, and the exponential-growth stage. The onset and growth of the double-tearing mode significantly depend on the boundary magnetic perturbations, particularly in the early development stage of the mode. The influences of the magnetic perturbation amplitude on the mode for different separations of the two rational surfaces are also discussed.

The dynamical conductance of graphene tunnelling structures.

PubMed

Zhang, Huan; Chan, K S; Lin, Zijing

2011-12-16

The dynamical conductances of graphene tunnelling structures were numerically calculated using the scattering matrix method with the interaction effect included in a phenomenological approach. The overall single-barrier dynamical conductance is capacitative. Transmission resonances in the single-barrier structure lead to dips in the capacitative imaginary part of the response. This is different from the ac responses of typical semiconductor nanostructures, where transmission resonances usually lead to inductive peaks. The features of the dips depend on the Fermi energy. When the Fermi energy is below half of the barrier height, the dips are sharper. When the Fermi energy is higher than half of the barrier height, the dips are broader. Inductive behaviours can be observed in a double-barrier structure due to the resonances formed by reflection between the two barriers.

Efficient 525 nm laser generation in single or double resonant cavity

NASA Astrophysics Data System (ADS)

Liu, Shilong; Han, Zhenhai; Liu, Shikai; Li, Yinhai; Zhou, Zhiyuan; Shi, Baosen

2018-03-01

This paper reports the results of a study into highly efficient sum frequency generation from 792 and 1556 nm wavelength light to 525 nm wavelength light using either a single or double resonant ring cavity based on a periodically poled potassium titanyl phosphate crystal (PPKTP). By optimizing the cavity's parameters, the maximum power achieved for the resultant 525 nm laser was 263 and 373 mW for the single and double resonant cavity, respectively. The corresponding quantum conversion efficiencies were 8 and 77% for converting 1556 nm photons to 525 nm photons with the single and double resonant cavity, respectively. The measured intra-cavity single pass conversion efficiency for both configurations was about 5%. The performances of the sum frequency generation in these two configurations was studied and compared in detail. This work will provide guidelines for optimizing the generation of sum frequency generated laser light for a variety of configurations. The high conversion efficiency achieved in this work will help pave the way for frequency up-conversion of non-classical quantum states, such as the squeezed vacuum and single photon states. The proposed green laser source will be used in our future experiments, which includes a plan to generate two-color entangled photon pairs and achieve the frequency down-conversion of single photons carrying orbital angular momentum.

Millimeter-wave optical double resonance schemes for rapid assignment of perturbed spectra, with applications to the C{sup ~} {sup 1}B{sub 2} state of SO{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, G. Barratt, E-mail: barratt@mit.edu, E-mail: barratt.park@gmail.com; Womack, Caroline C.; Jiang, Jun

2015-04-14

Millimeter-wave detected, millimeter-wave optical double resonance (mmODR) spectroscopy is a powerful tool for the analysis of dense, complicated regions in the optical spectra of small molecules. The availability of cavity-free microwave and millimeter wave spectrometers with frequency-agile generation and detection of radiation (required for chirped-pulse Fourier-transform spectroscopy) opens up new schemes for double resonance experiments. We demonstrate a multiplexed population labeling scheme for rapid acquisition of double resonance spectra, probing multiple rotational transitions simultaneously. We also demonstrate a millimeter-wave implementation of the coherence-converted population transfer scheme for background-free mmODR, which provides a ∼10-fold sensitivity improvement over the population labeling scheme.more » We analyze perturbations in the C{sup ~} state of SO{sub 2}, and we rotationally assign a b{sub 2} vibrational level at 45 328 cm{sup −1} that borrows intensity via a c-axis Coriolis interaction. We also demonstrate the effectiveness of our multiplexed mmODR scheme for rapid acquisition and assignment of three predissociated vibrational levels of the C{sup ~} state of SO{sub 2} between 46 800 and 47 650 cm{sup −1}.« less

A double expansion method for the frequency response of finite-length beams with periodic parameters

NASA Astrophysics Data System (ADS)

Ying, Z. G.; Ni, Y. Q.

2017-03-01

A double expansion method for the frequency response of finite-length beams with periodic distribution parameters is proposed. The vibration response of the beam with spatial periodic parameters under harmonic excitations is studied. The frequency response of the periodic beam is the function of parametric period and then can be expressed by the series with the product of periodic and non-periodic functions. The procedure of the double expansion method includes the following two main steps: first, the frequency response function and periodic parameters are expanded by using identical periodic functions based on the extension of the Floquet-Bloch theorem, and the period-parametric differential equation for the frequency response is converted into a series of linear differential equations with constant coefficients; second, the solutions to the linear differential equations are expanded by using modal functions which satisfy the boundary conditions, and the linear differential equations are converted into algebraic equations according to the Galerkin method. The expansion coefficients are obtained by solving the algebraic equations and then the frequency response function is finally determined. The proposed double expansion method can uncouple the effects of the periodic expansion and modal expansion so that the expansion terms are determined respectively. The modal number considered in the second expansion can be reduced remarkably in comparison with the direct expansion method. The proposed double expansion method can be extended and applied to the other structures with periodic distribution parameters for dynamics analysis. Numerical results on the frequency response of the finite-length periodic beam with various parametric wave numbers and wave amplitude ratios are given to illustrate the effective application of the proposed method and the new frequency response characteristics, including the parameter-excited modal resonance, doubling-peak frequency response and remarkable reduction of the maximum frequency response for certain parametric wave number and wave amplitude. The results have the potential application to structural vibration control.

Transmitted spectral modulation of double-ring resonator using liquid crystals in terahertz range

NASA Astrophysics Data System (ADS)

Sun, Huijuan; Zhou, Qingli; Wang, Xiumin; Li, Chenyu; Wu, Ani; Zhang, Cunlin

2013-12-01

Metamaterials with subwavelength structural features show unique electromagnetic responses that are unattainable with natural materials. Recent research on these artificial materials has been pushed forward to the terahertz region because of potential applications in biological fingerprinting, security imaging, remote sensing, and high frequency magnetic and electric resonant devices. Active control of their properties could further facilitate and open up new applications in terms of modulation and switching. Liquid crystals, which have been the subject of research for more than a century, have the unique properties for the development of many other optical components such as light valves, tunable filters and tunable lenses. In this paper, we investigated the transmitted spectral modulation in terahertz range by using liquid crystals (5CB and TEB300) covering on the fabricated double-ring resonators to realize the shift of the resonance frequency. Our obtained results indicate the low frequency resonance shows the obvious blue-shift, while the location of high frequency resonance is nearly unchanged. We believe this phenomenon is related to not only the refractive index of the covering liquid crystals but also the resonant mechanism of both resonances.

Determining the dominant partial wave contributions from angular distributions of single- and double-polarization observables in pseudoscalar meson photoproduction

NASA Astrophysics Data System (ADS)

Wunderlich, Y.; Afzal, F.; Thiel, A.; Beck, R.

2017-05-01

This work presents a simple method to determine the significant partial wave contributions to experimentally determined observables in pseudoscalar meson photoproduction. First, fits to angular distributions are presented and the maximum orbital angular momentum Lmax needed to achieve a good fit is determined. Then, recent polarization measurements for γ p → π0 p from ELSA, GRAAL, JLab and MAMI are investigated according to the proposed method. This method allows us to project high-spin partial wave contributions to any observable as long as the measurement has the necessary statistical accuracy. We show, that high precision and large angular coverage in the polarization data are needed in order to be sensitive to high-spin resonance states and thereby also for the finding of small resonance contributions. This task can be achieved via interference of these resonances with the well-known states. For the channel γ p → π0 p, those are the N(1680)5/2+ and Δ(1950)7/2+, contributing to the F-waves.

Convergence of Legendre Expansion of Doppler-Broadened Double Differential Elastic Scattering Cross Section

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arbanas, Goran; Dunn, Michael E; Larson, Nancy M

2012-01-01

Convergence properties of Legendre expansion of a Doppler-broadened double-differential elastic neutron scattering cross section of {sup 238}U near the 6.67 eV resonance at temperature 10{sup 3} K are studied. A variance of Legendre expansion from a reference Monte Carlo computation is used as a measure of convergence and is computed for as many as 15 terms in the Legendre expansion. When the outgoing energy equals the incoming energy, it is found that the Legendre expansion converges very slowly. Therefore, a supplementary method of computing many higher-order terms is suggested and employed for this special case.

Effect of the δ-potential on spin-dependent electron tunneling in double barrier semiconductor heterostructure

NASA Astrophysics Data System (ADS)

Chandrasekar, L. Bruno; Gnanasekar, K.; Karunakaran, M.

2018-06-01

The effect of δ-potential was studied in GaAs/Ga0.6Al0·4As double barrier heterostructure with Dresselhaus spin-orbit interaction. The role of barrier height and position of the δ- potential in the well region was analysed on spin-dependent electron tunneling using transfer matrix method. The spin-separation between spin-resonances on energy scale depends on both height and position of the δ- potential, whereas the tunneling life time of electrons highly influenced by the position of the δ- potential and not on the height. These results might be helpful for the fabrication of spin-filters.

Subthreshold resonances and resonances in the R -matrix method for binary reactions and in the Trojan horse method

NASA Astrophysics Data System (ADS)

Mukhamedzhanov, A. M.; Shubhchintak, Bertulani, C. A.

2017-08-01

In this paper we discuss the R -matrix approach to treat the subthreshold resonances for the single-level and one-channel and for the single-level and two-channel cases. In particular, the expression relating the asymptotic normalization coefficient (ANC) with the observable reduced width, when the subthreshold bound state is the only channel or coupled with an open channel, which is a resonance, is formulated. Since the ANC plays a very important role in nuclear astrophysics, these relations significantly enhance the power of the derived equations. We present the relationship between the resonance width and the ANC for the general case and consider two limiting cases: wide and narrow resonances. Different equations for the astrophysical S factors in the R -matrix approach are presented. After that we discuss the Trojan horse method (THM) formalism. The developed equations are obtained using the surface-integral formalism and the generalized R -matrix approach for the three-body resonant reactions. It is shown how the Trojan horse (TH) double-differential cross section can be expressed in terms of the on-the-energy-shell astrophysical S factor for the binary subreaction. Finally, we demonstrate how the THM can be used to calculate the astrophysical S factor for the neutron generator 13C(α ,n )16O in low-mass AGB stars. At astrophysically relevant energies this astrophysical S factor is controlled by the threshold level 1 /2+,Ex=6356 keV. Here, we reanalyzed recent TH data taking into account more accurately the three-body effects and using both assumptions that the threshold level is a subthreshold bound state or it is a resonance state.

One- and two-dimensional pulse electron paramagnetic resonance spectroscopy: concepts and applications.

PubMed

Van Doorslaer, S; Schweiger, A

2000-06-01

During the last two decades, the possibilities of pulse electron paramagnetic resonance (EPR) and pulse electron nuclear double resonance (ENDOR) spectroscopy have increased tremendously. While at the beginning of the 1980s pulse-EPR and ENDOR applications were still a rarity, the techniques are now very frequently applied in chemistry, physics, materials science, biology and mineralogy. This is mainly due to the considerable efforts invested in the last few years on instrument development and pulse-sequence design. Pulse-EPR spectrometers are now commercially available, which enables many research groups to use these techniques. In this work, an overview of state-of-the-art pulse EPR and ENDOR spectroscopy is given. The rapid expansion of the field, however, does not allow us to give an exhaustive record of all the pulse methods introduced so far. After a brief and very qualitative description of the basic principles of pulse EPR, we discuss some of the experiments in more detail and illustrate the potential of the methods with a number of selected applications.

Double Negative Materials (DNM), Phenomena and Applications

DTIC Science & Technology

2009-07-01

Nanoparticles Formed by Pairs Of Concentric Double-Negative (DNG), Single-Negative ( SNG ) and/or Double-Positive (DPS) Metamaterial Layers.” J. Appl...material RRL Rapid Research Letters SHG second-harmonic generation SNG single-negative SSR split-ring resonator A-1 Appendix A. October 2008...Pairs of Concentric Double-Negative (DNG), Single-Negative ( SNG ), and/or Double-Positive (DPS) Metamaterial Layers.” J. Appl. Phys. 97, no. 9 (May

Instantons re-examined: dynamical tunneling and resonant tunneling.

PubMed

Le Deunff, Jérémy; Mouchet, Amaury

2010-04-01

Starting from trace formulas for the tunneling splittings (or decay rates) analytically continued in the complex time domain, we obtain explicit semiclassical expansions in terms of complex trajectories that are selected with appropriate complex-time paths. We show how this instantonlike approach, which takes advantage of an incomplete Wick rotation, accurately reproduces tunneling effects not only in the usual double-well potential but also in situations where a pure Wick rotation is insufficient, for instance dynamical tunneling or resonant tunneling. Even though only one-dimensional autonomous Hamiltonian systems are quantitatively studied, we discuss the relevance of our method for multidimensional and/or chaotic tunneling.

Development of a Si/ SiO 2-based double quantum dot charge qubit with dispersive microwave readout

NASA Astrophysics Data System (ADS)

House, M. G.; Henry, E.; Schmidt, A.; Naaman, O.; Siddiqi, I.; Pan, H.; Xiao, M.; Jiang, H. W.

2011-03-01

Coupling of a high-Q microwave resonator to superconducting qubits has been successfully used to prepare, manipulate, and read out the state of a single qubit, and to mediate interactions between qubits. Our work is geared toward implementing this architecture in a semiconductor qubit. We present the design and development of a lateral quantum dot in which a superconducting microwave resonator is capacitively coupled to a double dot charge qubit. The device is a silicon MOSFET structure with a global gate which is used to accumulate electrons at a Si/ Si O2 interface. A set of smaller gates are used to deplete these electrons to define a double quantum dot and adjacent conduction channels. Two of these depletion gates connect directly to the conductors of a 6 GHz co-planar stripline resonator. We present measurements of transport and conventional charge sensing used to characterize the double quantum dot, and demonstrate that it is possible to reach the few-electron regime in this system. This work is supported by the DARPA-QuEST program.

Remote double resonance coupling of radar energy to ionospheric irregularities

NASA Technical Reports Server (NTRS)

Kennel, C. F.

1971-01-01

Experimental results indicate that low frequency modulation of a high power radar beam, tuned to one of the critical frequencies of the ionosphere, may produce field-aligned density irregularities when the modulation frequency matches an ionospheric eigenfrequency. By choosing the radar carrier frequency and polarization, a number of interaction layers were selected. The variety of possible excitations shows that the double resonance technique may be adaptable to a number of different objectives.

Ground-state IVR of jet-cooled p-alkylphenols and p-alkylanilines studied by stimulated emission ion dip and stimulated Raman-UV optical double-resonance spectroscopies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ebata, T.; Ito, M.

1992-04-16

This paper reports the intramolecular vibrational redistribution (IVR) of the jet-cooled p-alkylphenols and p-alkylanilines in S{sub 0} state by using stimulated emission ion dip and stimulated raman-UV optical double-resonance spectroscopy. The IVR rate constants of several vibrational levels localized in the benzene ring are estimated. 31 refs., 12 figs., 4 tabs.

Crossed-coil detection of two-photon excited nuclear quadrupole resonance

NASA Astrophysics Data System (ADS)

Eles, Philip T.; Michal, Carl A.

2005-08-01

Applying a recently developed theoretical framework for determining two-photon excitation Hamiltonians using average Hamiltonian theory, we calculate the excitation produced by half-resonant irradiation of the pure quadrupole resonance of a spin-3/2 system. This formalism provides expressions for the single-quantum and double-quantum nutation frequencies as well as the Bloch-Siegert shift. The dependence of the excitation strength on RF field orientation and the appearance of the free-induction signal along an axis perpendicular to the excitation field provide an unmistakable signature of two-photon excitation. We demonstrate single- and double-quantum excitation in an axially symmetric system using 35Cl in a single crystal of potassium chlorate ( ωQ = 28 MHz) with crossed-coil detection. A rotation plot verifies the orientation dependence of the two-photon excitation, and double-quantum coherences are observed directly with the application of a static external magnetic field.

Double peak searches for scalar and pseudoscalar resonances at the LHC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carena, Marcela; Huang, Peisi; Ismail, Ahmed

2016-12-01

Many new physics models contain a neutral scalar resonance that can be predominantly produced via gluon fusion through loops. In such a case, there could be important effects of additional particles, that in turn may hadronize before decaying and form bound states. This interesting possibility may lead to novel signatures with double peaks that can be searched for at the LHC. We study the phenomenology of double peak searches in diboson final states from loop-induced production and decay of a new neutral spin-0 resonance at the LHC. The loop-induced couplings should be mediated by particles carrying color and electroweak chargemore » that after forming bound states will induce a second peak in the diboson invariant mass spectrum near twice their mass. A second peak could be present via loop-induced couplings into gg (dijet),gamma gamma and Z gamma final states as well as in the WW and ZZ channels for the case of a pseudoscalar resonance or for scalars with suppressed tree-level coupling to gauge bosons« less

Double peak searches for scalar and pseudoscalar resonances at the LHC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carena, Marcela; Huang, Peisi; Ismail, Ahmed

2016-12-01

Many new physics models contain a neutral scalar resonance that can be predominantly produced via gluon fusion through loops. In such a case, there could be important effects of additional particles, that in turn may hadronize before decaying and form bound states. This interesting possibility may lead to novel signatures with double peaks that can be searched for at the LHC. We study the phenomenology of double peak searches in diboson final states from loop induced production and decay of a new neutral spin-0 resonance at the LHC. The loop-induced couplings should be mediated by particles carrying color and electroweak charge that after forming bound states will induce a second peak in the diboson invariant mass spectrum near twice their mass. As a result, a second peak could be present via loop-induced couplings intomore » $gg$ (dijet), $$\\gamma\\gamma$$ and $$Z\\gamma$$ final states as well as in the $WW$ and $ZZ$ channels for the case of a pseudo-scalar resonance or for scalars with suppressed tree-level coupling to gauge bosons.« less

Labyrinth double split open loop resonator based bandpass filter design for S, C and X-band application

NASA Astrophysics Data System (ADS)

Alam, Jubaer; Faruque, Mohammad Rashed Iqbal; Tariqul Islam, Mohammad

2018-07-01

Nested circular shaped Labyrinth double split open loop resonators (OLRs) are introduced in this article to design a triple bandpass filter for 3.01 GHz, 7.39 GHz and 12.88 GHz applications. A Rogers RT-5880 is used as a substrate to design the proposed passband filter which has a succinct structure where the attainment of the resonator is explored both integrally and experimentally. The same structure is designed on both sides of the substrate and an analysis is made on the current distribution. Based on the proposed resonator, a bandpass filter is designed and fabricated to justify the perception focusing on 3.01 GHz, 7.39 GHz and 12.88 GHz. It has also been observed by the Nicolson–Ross–Weir approach at the filtering frequencies. The effective electromagnetic parameters retrieved from the simulation of the S-parameters imply that the OLR metamaterial filter shows negative refraction bands. Having an auspicious design and double negative characteristics, this structure is suitable for triple passband filters, particularly for S, C and X-band applications.

Observation of Mollow Triplets with Tunable Interactions in Double Lambda Systems of Individual Hole Spins

NASA Astrophysics Data System (ADS)

Lagoudakis, K. G.; Fischer, K. A.; Sarmiento, T.; McMahon, P. L.; Radulaski, M.; Zhang, J. L.; Kelaita, Y.; Dory, C.; Müller, K.; Vučković, J.

2017-01-01

Although individual spins in quantum dots have been studied extensively as qubits, their investigation under strong resonant driving in the scope of accessing Mollow physics is still an open question. Here, we have grown high quality positively charged quantum dots embedded in a planar microcavity that enable enhanced light-matter interactions. Under a strong magnetic field in the Voigt configuration, individual positively charged quantum dots provide a double lambda level structure. Using a combination of above-band and resonant excitation, we observe the formation of Mollow triplets on all optical transitions. We find that when the strong resonant drive power is used to tune the Mollow-triplet lines through each other, we observe anticrossings. We also demonstrate that the interaction that gives rise to the anticrossings can be controlled in strength by tuning the polarization of the resonant laser drive. Quantum-optical modeling of our system fully captures the experimentally observed spectra and provides insight on the complicated level structure that results from the strong driving of the double lambda system.

A novel double-layer molecularly imprinted polymer film based surface plasmon resonance for determination of testosterone in aqueous media

NASA Astrophysics Data System (ADS)

Tan, Yuan; Jing, Lijing; Ding, Yonghong; Wei, Tianxin

2015-07-01

This work aimed to prepare a novel double-layer structure molecularly imprinted polymer film (MIF) on the surface plasmon resonance (SPR) sensor chips for detection of testosterone in aqueous media. The film was synthesized by in-situ UV photo polymerization. Firstly, the modification of gold surface of SPR chip was performed by 1-dodecanethiol. Then double-layer MIF was generated on the 1-dodecanethiol modified gold surface. The non-modified and imprinted surfaces were characterized by atomic force microscopy (AFM), fourier transform infrared (FTIR) spectroscopy and contact angle measurements. Analysis of SPR spectroscopy showed that the imprinted sensing film displayed good selectivity for testosterone compared to other analogues and the non-imprinted polymer film (NIF). Within the concentrations range of 1 × 10-12-1 × 10-8 mol/L, the coupling angle changes of SPR were linear with the negative logarithm of testosterone concentrations (R2 = 0.993). Based on a signal/noise ratio of three, the detection limit was estimated to be 10-12 mol/L. Finally, the developed MIF was successfully applied to the seawater detection of testosterone. The results in the experiments suggested that a combination of SPR sensing with MIF was a promising alternative method for detection of testosterone in aqueous media.

High finesse microfiber knot resonators made from double-ended tapered fibers.

PubMed

Xiao, Limin; Birks, T A

2011-04-01

We fabricated optical microfiber knot resonators from thin tapered fibers (diameter down to 1 μm) linked to untapered fiber at both ends. We demonstrated a finesse of about 100, over twice as high as previously reported for microfiber resonators. Low-loss encapsulation of microfiber knot resonators in hydrophobic silica aerogel was also investigated.

Terahertz plasmon-induced transparency based on asymmetric dual-disk resonators coupled to a semiconductor InSb waveguide and its biosensor application

NASA Astrophysics Data System (ADS)

Shahamat, Yadollah; Vahedi, Mohammad

2017-06-01

An ultracompact double eight-shaped plasmonic structure for the realization of plasmon-induced transparency (PIT) in the terahertz (THz) region has been studied. The device consists of a semiconductor-insulator-semiconductor bus waveguide coupled to the dual-disk resonators. Indium antimonide is employed to excite SPP in the THz region. The transmission characteristics of the proposed device are simulated numerically by the finite-difference time-domain method. In addition, a theoretical analysis based on the coupled-mode theory for transmission features is presented and compared with the numerical results. Results are in good agreement. Also, the dependence of PIT frequency characteristics on the radius of the outer disk is discussed in detail. In addition, by removing one of the outer disk resonators, double-PIT peaks can be observed in the transmission spectrum, and the physical mechanism of the appeared peaks is investigated. Finally, an application of the proposed structure for distinguishing different states of DNA molecules is discussed. Results show that the maximum sensitivity with 654 GHz/RIU-1 could be obtained for a single PIT structure. The frequency shifts equal to 37 and 99 GHz could be observed for the denatured and the hybridized DNA states, respectively.

Evolution of transmission spectra of double cladding fiber during etching

NASA Astrophysics Data System (ADS)

Ivanov, Oleg V.; Tian, Fei; Du, Henry

2017-11-01

We investigate the evolution of optical transmission through a double cladding fiber-optic structure during etching. The structure is formed by a section of SM630 fiber with inner depressed cladding between standard SMF-28 fibers. Its transmission spectrum exhibits two resonance dips at wavelengths where two cladding modes have almost equal propagation constants. We measure transmission spectra with decreasing thickness of the cladding and show that the resonance dips shift to shorter wavelengths, while new dips of lower order modes appear from long wavelength side. We calculate propagation constants of cladding modes and resonance wavelengths, which we compare with the experiment.

Growth and characterization of high current density, high-speed InAs/AlSb resonant tunneling diodes

NASA Technical Reports Server (NTRS)

Soderstrom, J. R.; Brown, E. R.; Parker, C. D.; Mahoney, L. J.; Yao, J. Y.

1991-01-01

InAs/AlSb double-barrier resonant tunneling diodes with peak current densities up to 370,000 A/sq cm and high peak-to-valley current ratios of 3.2 at room temperature have been fabricated. The peak current density is well-explained by a stationary-state transport model with the two-band envelope function approximation. The valley current density predicted by this model is less than the experimental value by a factor that is typical of the discrepancy found in other double-barrier structures. It is concluded that threading dislocations are largely inactive in the resonant tunneling process.

Reaction. pi. /sup -/p. --> pi. /sup -/. pi. /sup +/. pi. /sup -/p at 8 GeV/c

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kitagaki, T.; Tanaka, S.; Yuta, H.

1982-10-01

Results from a high-statistics experiment involving an exposure of the SLAC 82-in. hydrogen bubble chamber to a beam of 8-GeV/c ..pi../sup -/ yielding a final state of ..pi../sup -/..pi../sup +/..pi../sup -/p are presented. Copious production of rho, ..delta../sup + +/, and f is found. Considerable quasi-two-body production in which one particle decays to one of the above resonances is also observed. Some double-resonance production involving baryon and meson resonances is also seen. The production properties of rho, ..delta../sup + +/, and f mesons are well described by a double-Regge model.

Two-resonance probe for measuring electron density in low-pressure plasmas

NASA Astrophysics Data System (ADS)

Kim, D. W.; You, S. J.; Kim, S. J.; Kim, J. H.; Oh, W. Y.

2017-04-01

A technique for measuring double-checked electron density using two types of microwave resonance is presented. Simultaneous measurement of the resonances (plasma and quarter-wavelength resonator resonances), which were used for the cutoff probe (CP) and hairpin probe (HP), was achieved by the proposed microwave resonance probe. The developed two-resonance probe (TRP) consists of parallel separated coaxial cables exposing the radiation and detection tips. The structure resembles that of the CP, except the gapped coaxial cables operate not only as a microwave feeder for the CP but also as a U- shaped quarter-wavelength resonator for the HP. By virtue of this structure, the microwave resonances that have typically been used for measuring the electron density for the CP and HP were clearly identified on the microwave transmission spectrum of the TRP. The two types of resonances were measured experimentally under various power and pressure conditions for the plasma. A three-dimensional full-wave simulation model for the TRP is also presented and used to investigate and reproduce the resonances. The electron densities inferred from the resonances were compared and showed good agreement. Quantitative differences between the densities were attributed to the effects of the sheath width and spatial density gradient on the resonances. This accessible technique of using the TRP to obtain double-checked electron densities may be useful for comparative study and provides complementary uses for the CP and HP.

Resonant tunneling structures based on epitaxial graphene on SiC

NASA Astrophysics Data System (ADS)

Nguyen, V. Hung; Bournel, A.; Dollfus, P.

2011-12-01

Recently some experiments have suggested that graphene epitaxially grown on SiC can exhibit an energy bandgap of 260 meV, which enhances the potential of this material for electronic applications. On this basis, we propose to use spatial doping to generate graphene-on-SiC double-barrier structures. The non-equilibrium Green's function technique for solving the massive Dirac model is applied to highlight typical transport phenomena such as the electron confinement and the resonant tunneling effects. The I-V characteristics of graphene resonant tunneling diodes were then investigated and the effect of different device parameters was discussed. It is finally shown that this kind of double-barrier junction provides an efficient way to confine the charge carriers in graphene and to design graphene resonant tunneling structures.

Facile fabrication of high-efficiency near-infrared absorption film with tungsten bronze nanoparticle dense layer

NASA Astrophysics Data System (ADS)

Lee, Seong Yun; Kim, Jae Young; Lee, Jun Young; Song, Ho Jun; Lee, Sangkug; Choi, Kyung Ho; Shin, Gyojic

2014-06-01

An excellent transparent film with effective absorption property in near-infrared (NIR) region based on cesium-doped tungsten oxide nanoparticles was fabricated using a facile double layer coating method via the theoretical considerations. The optical performance was evaluated; the double layer-coated film exhibited 10% transmittance at 1,000 nm in the NIR region and over 80% transmittance at 550 nm in the visible region. To optimize the selectivity, the optical spectrum of this film was correlated with a theoretical model by combining the contributions of the Mie-Gans absorption-based localized surface plasmon resonance and reflections by the interfaces of the heterogeneous layers and the nanoparticles in the film. Through comparison of the composite and double layer coating method, the difference of the nanoscale distances between nanoparticles in each layer was significantly revealed. It is worth noting that the nanodistance between the nanoparticles decreased in the double layer film, which enhanced the optical properties of the film, yielding a haze value of 1% or less without any additional process. These results are very attractive for the nanocomposite coating process, which would lead to industrial fields of NIR shielding and thermo-medical applications.

Nonequilibrium Green's function theory of resonant steady state photoconduction in a double quantum well FET subject to THz radiation at plasmon frequency

NASA Astrophysics Data System (ADS)

Morgenstern Horing, Norman J.; Popov, Vyacheslav V.

2006-04-01

Recent experimental observations by X.G. Peralta and S.J. Allen, et al. of dc photoconductivity resonances in steady source-drain current subject to terahertz radiation in a grid-gated double-quantum well FET suggested an association with plasmon resonances. This association was definitively confirmed for some parameter ranges in our detailed electrodynamic absorbance calculations. In this paper we propose that the reason that the dc photoconductance resonances match the plasmon resonances in semiconductors is based on a nonlinear dynamic screening mechanism. In this, we employ a shielded potential approximation that is nonlinear in the terahertz field to determine the nonequilibrium Green's function and associated density perturbation that govern the nonequilibrium dielectric polarization of the medium. This ''conditioning'' of the system by the incident THz radiation results in resonant polarization response at the plasmon frequencies which, in turn, causes a sharp drop of the resistive shielded impurity scattering potentials and attendant increase of the dc source-drain current. This amounts to disabling the impurity scattering mechanism by plasmon resonant behavior in nonlinear screening.

Determination of thorium (IV) using isophthalaldehyde-tetrapyrrole as probe by resonance light scattering, second-order scattering and frequency-doubling scattering spectra

NASA Astrophysics Data System (ADS)

Wang, Jiao; Xue, Jinhua; Xiao, Xilin; Xu, Li; Jiang, Min; Peng, Pengcheng; Liao, Lifu

2017-12-01

The coordination reaction of thorium (IV) with a ditopic bidentate ligand to form supramolecular polymer was studied by resonance light scattering (RLS) spectra, second-order scattering (SOS) spectra and frequency-doubling scattering (FDS) spectra, respectively. The ditopic bidentate ligand is isophthalaldehyde-tetrapyrrole (IPTP). It was synthesized through a condensation reaction of isophthalaldehyde with pyrrole. The formation of supramolecular polymer results in remarkable intensity enhancements of the three light scattering signals. The maximum scattering wavelengths of RLS, FDS and SOS were 290, 568 and 340 nm, respectively. The reaction was used to establish new light scattering methods for the determination of thorium (IV) by using IPTP as probe. Under optimum conditions, the intensity enhancements of RLS, SOS and FDS were directly proportional to the concentration of thorium (IV) in the ranges of 0.01 to 1.2 μg mL- 1, 0.05 to 1.2 μg mL- 1 and 0.05 to 1.2 μg mL- 1, respectively. The detection limits were 0.003 μg mL- 1, 0.012 μg mL- 1 and 0.021 μg mL- 1, respectively. The methods were suitable for analyzing thorium (IV) in actual samples. The results show acceptable recoveries and precision compared with a reference method.

From Sommerfeld and Brillouin forerunners to optical precursors

NASA Astrophysics Data System (ADS)

Macke, Bruno; Ségard, Bernard

2013-04-01

The Sommerfeld and Brillouin forerunners generated in a single-resonance absorbing medium by an incident step-modulated pulse are theoretically considered in the double limit where the susceptibility of the medium is weak and the resonance is narrow. Combining direct Laplace-Fourier integration and calculations by the saddle-point method, we establish an explicit analytical expression of the transmitted field valid at any time, even when the two forerunners significantly overlap. We examine how their complete overlapping, occurring for shorter propagation distances, originates the formation of the unique transient currently named resonant precursor or dynamical beat. We obtain an expression of this transient identical to that usually derived within the slowly varying envelope approximation in spite of the initial discontinuity of the incident field envelope. The dynamical beats and 0π pulses generated by ultrashort incident pulses are also briefly examined.

Adiabatic passage of radio-frequency-assisted Förster resonances in Rydberg atoms for two-qubit gates and the generation of Bell states

NASA Astrophysics Data System (ADS)

Beterov, I. I.; Hamzina, G. N.; Yakshina, E. A.; Tretyakov, D. B.; Entin, V. M.; Ryabtsev, I. I.

2018-03-01

High-fidelity entangled Bell states are of great interest in quantum physics. Entanglement of ultracold neutral atoms in two spatially separated optical dipole traps is promising for implementation of quantum computing and quantum simulation and for investigation of Bell states of material objects. We propose a method to entangle two atoms via long-range Rydberg-Rydberg interaction. Alternative to previous approaches, based on Rydberg blockade, we consider radio-frequency-assisted Stark-tuned Förster resonances in Rb Rydberg atoms. To reduce the sensitivity of the fidelity of Bell states to the fluctuations of interatomic distance, we propose to use the double adiabatic passage across the radio-frequency-assisted Stark-tuned Förster resonances, which results in a deterministic phase shift of the collective two-atom state.

Infrared/Terahertz Double Resonance for Chemical Remote Sensing: Signatures and Performance Predictions

DTIC Science & Technology

2011-01-01

remote sensing , such as Fourier-transform infrared spectroscopy, has limited recognition specificity because of atmospheric pressure broadening. Active interrogation techniques promise much greater chemical recognition that can overcome the limits imposed by atmospheric pressure broadening. Here we introduce infrared - terahertz (IR/THz) double resonance spectroscopy as an active means of chemical remote sensing that retains recognition specificity through rare, molecule-unique coincidences between IR molecular absorption and a line-tunable CO2

Magic angle for barrier-controlled double quantum dots

NASA Astrophysics Data System (ADS)

Yang, Xu-Chen; Wang, Xin

2018-01-01

We show that the exchange interaction of a singlet-triplet spin qubit confined in double quantum dots, when being controlled by the barrier method, is insensitive to a charged impurity lying along certain directions away from the center of the double-dot system. These directions differ from the polar axis of the double dots by the magic angle, equaling arccos(1 /√{3 })≈54 .7∘ , a value previously found in atomic physics and nuclear magnetic resonance. This phenomenon can be understood from an expansion of the additional Coulomb interaction created by the impurity, but also relies on the fact that the exchange interaction solely depends on the tunnel coupling in the barrier-control scheme. Our results suggest that for a scaled-up qubit array, when all pairs of double dots rotate their respective polar axes from the same reference line by the magic angle, crosstalk between qubits can be eliminated, allowing clean single-qubit operations. While our model is a rather simplified version of actual experiments, our results suggest that it is possible to minimize unwanted couplings by judiciously designing the layout of the qubits.

Micromachined quartz crystal resonator arrays for bioanalytical applications

NASA Astrophysics Data System (ADS)

Kao, Ping

This work presents the design, fabrication and investigation of high frequency quartz crystal resonator arrays and their application for analyzing interfacial layers and sensing purposes. An 8-pixel micromachined quartz crystal resonator array with a fundamental resonance frequency of ˜66 MHz has been fabricated, tested and used in this work. One dimensional model for the characterization of resonator behavior for single or multiple viscoelastic layers under liquid ambient are developed by continuum mechanics approach as well as using an equivalent electrical admittance analysis approach. The investigation of thin interfacial layer between solid (electrode) and liquid phases are reported in terms of the improved resolution of viscoelasitc characteristics of adsorbed layer arising from the use of high frequency resonators. Analyzed layers include globular proteins layer under phosphate buffer solution (PBS) with molecular weights spanning three orders of magnitude, multilayers of avidin and biotin labeled bovine albumin under PBS and diffuse double layer induced by DC bias under 0.5 M sulfuric acid solution. The second half of the dissertation focuses on biosensing applications of quartz resonator arrays. The selective functionalization of 3,3'-Dithiobis (sulfosuccinimidylpropionate) (DTSSP) by physical masking method was first used for specifically detecting avidin molecules. The selective immobilization of thiol modified single stranded DNA probes via electrochemical methods was used for the specific detection of Respiratory Syncytial Virus (RSV) G-gene. The work demonstrates that micromachined quartz crystal resonator arrays could be a powerful analytical tool of investigating interfacial region and can be readily configured as biosenors that can be used for label-free, quantitative assays using extremely small volumes of analytes.

Evaluation of magnetic resonance signal modification induced by hyaluronic acid therapy in chondromalacia patellae: a preliminary study.

PubMed

Magarelli, N; Palmieri, D; Ottaviano, L; Savastano, M; Barbato, M; Leone, A; Maggialetti, A; Ciampa, F P; Bonomo, L

2008-01-01

Hyaluronic Acid (HA) is an alternative method for the treatment of osteoarthritis (OA), which acts on pain through a double action: anti-inflammatory and synovial fluid (SF) visco-supplementation. Magnetic Resonance Imaging (MRI), utilizing specific sequences, is a valid method for studying the initial phase of chondral damage. The analysis of the data, obtained through the intensity of values taken by positioning Region of Interest (ROIs) within the lesion, determining the differences before and after treatment with HA injected into the knee. The results obtained after six months and one year from the injection were statistically different in respect to those taken before, immediately and after three months of treatment. MRI represents a valid tool to evaluate the grade of chondromalacia patellae and also to follow the cartilage modification induced by HA therapy.

Models of Intracavity Frequency Doubled Lasers

DTIC Science & Technology

1990-01-01

Intermittency; Intermittency Theory; Entropies and Dimension with Intermittency; Resonances, Frobenius - Perron Operators and Power Spectra; and Scaling and...to finding a measure is to approximate the Frobenius - Perron operator, whose domain is the set of measures on M (see, e.g., Li, 1976). An invariant...measure of the system is a fixed point of the Frobenius - Perron operator, and an iterative method using this operator can be shown to converge to an

Risperidone and Divalproex Differentially Engage the Fronto-Striato-Temporal Circuitry in Pediatric Mania: A Pharmacological Functional Magnetic Resonance Imaging Study

ERIC Educational Resources Information Center

Pavuluri, Mani N.; Passarotti, Alessandra M.; Fitzgerald, Jacklynn M.; Wegbreit, Ezra; Sweeney, John A.

2012-01-01

Objective: The current study examined the impact of risperidone and divalproex on affective and working memory circuitry in patients with pediatric bipolar disorder (PBD). Method: This was a six-week, double-blind, randomized trial of risperidone plus placebo versus divalproex plus placebo for patients with mania (n = 21; 13.6 [plus or minus] 2.5…

Design and test of a double-nuclear RF coil for 1H MRI and 13C MRSI at 7 T

NASA Astrophysics Data System (ADS)

Rutledge, Omar; Kwak, Tiffany; Cao, Peng; Zhang, Xiaoliang

2016-06-01

RF coil operation at the ultrahigh field of 7 T is fraught with technical challenges that limit the advancement of novel human in vivo applications at 7 T. In this work, a hybrid technique combining a microstrip transmission line and a lumped-element L-C loop coil to form a double-nuclear RF coil for proton magnetic resonance imaging and carbon magnetic resonance spectroscopy at 7 T was proposed and investigated. Network analysis revealed a high Q-factor and excellent decoupling between the coils. Proton images and localized carbon spectra were acquired with high sensitivity. The successful testing of this novel double-nuclear coil demonstrates the feasibility of this hybrid design for double-nuclear MR imaging and spectroscopy studies at the ultrahigh field of 7 T.

Semi-monolithic cavity for external resonant frequency doubling and method of performing the same

NASA Technical Reports Server (NTRS)

Hemmati, Hamid (Inventor)

1999-01-01

The fabrication of an optical cavity for use in a laser, in a frequency doubling external cavity, or any other type of nonlinear optical device, can be simplified by providing the nonlinear crystal in combination with a surrounding glass having an index of refraction substantially equal to that of the nonlinear crystal. The closed optical path in this cavity is formed in the surrounding glass and through the nonlinear crystal which lies in one of the optical segments of the light path. The light is transmitted through interfaces between the surrounding glass in the nonlinear crystal through interfaces which are formed at the Brewster-angle to minimize or eliminate reflection.

Active multiple plasmon-induced transparencies with detuned asymmetric multi-rectangle resonators

NASA Astrophysics Data System (ADS)

Liu, Dongdong; Wang, Jicheng; Lu, Jian

2016-11-01

The phenomenon of plasmon-induced transparency (PIT) is realized in surface plasmon polariton waveguide at the visible and near-infrared ranges. By adding one and two resonant cavities, the PIT peak(s) was (were) achieved due to destructive interference between the side-coupled rectangle cavity and the bus waveguide. The proposed structures were demonstrated by the finite element method. The simulation results showed that for three rectangle resonators system, not only can we manipulate each single PIT window, but also the double PIT windows simultaneously by adjusting one of the geometrical parameters of the system; for four rectangle resonators system, by changing the widths, the lengths and the refractive index of three cavities simultaneously, we would realize treble PIT peaks and induce an off-to-on PIT optical response. Our novel plasmonic structures and the findings pave the way for new design and engineering of highly integrated optical circuit such as nanoscale optical switching, nanosensor and wavelength-selecting nanostructure.

Perturbation Facilitated Optical Optical Double Resonance Investigation of the Quintet Manifold of C_2 by Applying Two-Color Four-Wave Mixing

NASA Astrophysics Data System (ADS)

Bornhauser, Peter; Marquardt, Roberto; Radi, Peter

2014-06-01

The potential of four-wave mixing spectroscopy for deperturbation studies has been demonstrated by an analysis of the spin-orbit and L-uncoupling interaction between the d ^3Π_g,v=4 and the b ^3Σ_g^-, v=16 states of C_2. The double-resonance method provides unambiguous assignments of perturbed transitions by intermediate level labeling. Furthermore, the sensitivity of the method unveiled extra transitions that originate from the perturbing b ^3Σ_g^-, v=16 state. A following study has successfully applied the method to deperturb the d ^3Π_g,v=6 state of the dicarbon and lead to the discovery of the first high-spin state of C_2. The energetically lowest quintet (^5Π_g) %and the additionally perturbing b ^3Σ_g^-, v=19 state% has been characterized by applying a conventional Hamiltonian. The detailed study unraveled major issues of the so-called high-pressure band of C_2 which were initially observed back in 1910 and later observed in numerous experimental environments. In this work we take into account our recent studies on tri-carbon where we used perturbation-facilitated two-color resonant four-wave mixing spectroscopy to access the (dark) triplet manifold of C_3 from the singlet tilde{X}^1Σ_g^+ ground state via ``gate-way" levels (i.e. singlet-triplet mixed levels). In a similar way, we performed for this study perturbation-facilitated optical-optical double-resonance experiments to access the first excited quintet state of C_2 via ``gate-way states" in the perturbed d ^3Π_g,v=6. The newly found ^5Π_u state is characterized at rotational resolution by performing a least-squares fit of the observed transitions to a ^5Π_u - ^5Π_g Hamiltionian. The work represents a rare case of a successful analysis of a quintet manifold of a molecule exhibiting a singlet ground state (^1Σ_g^+). P. Bornhauser, G. Knopp, T. Gerber, and P.P. Radi, Journal of Molecular Spectroscopy 262, 69 (2010). P. Bornhauser, Y. Sych, G. Knopp, T. Gerber, and P.P. Radi, J. Chem. Phys. 134, 044302 (2011). A. Fowler, Monthly Notices of the Royal Astronomical Society 70, 484 (1910). Y. Sych, P. Bornhauser, G. Knopp, Y. Liu, T. Gerber, R. Marquardt, and P.P. Radi, J. Chem. Phys. 139, 154203 (2013).

Detecting RNA/DNA hybridization using double-labeled donor probes with enhanced fluorescence resonance energy transfer signals.

PubMed

Okamura, Yukio; Watanabe, Yuichiro

2006-01-01

Fluorescence resonance energy transfer (FRET) occurs when two fluorophores are in close proximity, and the emission energy of a donor fluorophore is transferred to excite an acceptor fluorophore. Using such fluorescently labeled oligonucleotides as FRET probes, makes possible specific detection of RNA molecules even if similar sequences are present in the environment. A higher ratio of signal to background fluorescence is required for more sensitive probe detection. We found that double-labeled donor probes labeled with BODIPY dye resulted in a remarkable increase in fluorescence intensity compared to single-labeled donor probes used in conventional FRET. Application of this double-labeled donor system can improve a variety of FRET techniques.

Ferromagnetic resonance study of the non-stoichiometric double perovskite Sr2Fe1+xMo1-xO6

NASA Astrophysics Data System (ADS)

Medina, J. De La Torre; Piraux, L.; Soto, T. E.; Morales, R.; Navarro, O.

2018-02-01

In this work we report a ferromagnetic resonance study on the magnetic properties of double perovskite compounds fab-ricated by solid state reaction. Based on a mean field approach, along with morphological considerations, we accurately determined the saturation magnetization of the non-stoichiometric double perovskite Sr2Fe1+xMo1-xO6. Our approach has revealed a direct in-fluence of composition on the overall magnetic behavior of these materials, providing complementary experimental evidence that corroborates previous theoretical findings. The understanding of the influence of composition is of paramount importance for the design of ferromagnetic oxides with tunable magnetic and magneto-transport behavior.

Single-resonator double-negative metamaterial

DOEpatents

Warne, Larry K.; Basilio, Lorena I.; Langston, William L.; Johnson, William A.; Ihlefeld, Jon; Ginn, III, James C.; Clem, Paul G.; Sinclair, Michael B.

2016-06-21

Resonances can be tuned in dielectric resonators in order to construct single-resonator, negative-index metamaterials. For example, high-contrast inclusions in the form of metallic dipoles can be used to shift the first electric resonance down (in frequency) to the first magnetic resonance, or alternatively, air splits can be used to shift the first magnetic resonance up (in frequency) near the first electric resonance. Degenerate dielectric designs become especially useful in infrared- or visible-frequency applications where the resonator sizes associated with the lack of high-permittivity materials can become of sufficient size to enable propagation of higher-order lattice modes in the resulting medium.

High-frequency response and the possibilities of frequency-tunable narrow-band terahertz amplification in resonant tunneling nanostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kapaev, V. V., E-mail: kapaev@sci.lebedev.ru; Kopaev, Yu. V.; Savinov, S. A.

2013-03-15

The characteristics of the high-frequency response of single- and double-well resonant tunneling structures in a dc electric field are investigated on the basis of the numerical solution of a time-dependent Schroedinger equation with open boundary conditions. The frequency dependence of the real part of high frequency conductivity (high-frequency response) in In{sub 0.53}Ga{sub 0.47}As/AlAs/InP structures is analyzed in detail for various values of the dc voltage V{sub dc} in the negative differential resistance (NDR) region. It is shown that double-well three-barrier structures are promising for the design of terahertz-band oscillators. The presence of two resonant states with close energies in suchmore » structures leads to a resonant (in frequency) response whose frequency is determined by the energy difference between these levels and can be controlled by varying the parameters of the structure. It is shown that, in principle, such structures admit narrow-band amplification, tuning of the amplification frequency, and a fine control of the amplification (oscillation) frequency in a wide range of terahertz frequencies by varying a dc electric voltage applied to the structure. Starting from a certain width of the central intermediate barrier in double-well structures, one can observe a collapse of resonances, where the structure behaves like a single-well system. This phenomenon imposes a lower limit on the oscillation frequency in three-barrier resonant tunneling structures.« less

Flux-dependent anti-crossing of resonances in parallel non-coupled double quantum dots

NASA Astrophysics Data System (ADS)

Joe, Yong S.; Hedin, Eric R.; Kim, Jiseok

2008-08-01

We present novel resonant phenomena through parallel non-coupled double quantum dots (QDs) embedded in each arm of an Aharonov-Bohm (AB) ring with magnetic flux passing through its center. The electron transmission through this AB ring with each QD formed by two short-range potential barriers is calculated using a scattering matrix at each junction and a transfer matrix in each arm. We show that as the magnetic flux modulates, a distortion of the grid-like square transmission occurs and an anti-crossing of the resonances appears. Hence, the modulation of magnetic flux in this system can have an equivalent effect to the control of inter-dot coupling between the two QDs.

Equal intensity double plasmon resonance of bimetallic quasi-nanocomposites based on sandwich geometry

NASA Astrophysics Data System (ADS)

Chakravadhanula, V. S. K.; Elbahri, M.; Schürmann, U.; Takele, H.; Greve, H.; Zaporojtchenko, V.; Faupel, F.

2008-06-01

We report a strategy to achieve a material showing equal intensity double plasmon resonance (EIDPR) based on sandwich geometry. We studied the interaction between localized plasmon resonances associated with different metal clusters (Au/Ag) on Teflon AF (TAF) in sandwich geometry. Engineering the EIDPR was done by tailoring the amount of Au/Ag and changing the TAF thickness. The samples were investigated by transmission electron microscopy (TEM) and UV-visible spectroscopy. Interestingly, and in agreement with the dipole-surface interaction, the critical barrier thickness for an optimum EIDPR was observed at 3.3 nm. The results clearly show a plasmon sequence effect and visualize the role of plasmon decay.

Dynamic entanglement transfer in a double-cavity optomechanical system

NASA Astrophysics Data System (ADS)

Huan, Tiantian; Zhou, Rigui; Ian, Hou

2015-08-01

We give a theoretical study of a double-cavity system in which a mechanical resonator beam is coupled to two cavity modes on both sides through radiation pressures. The indirect coupling between the cavities via the resonator sets up a correlation in the optomechanical entanglements between the two cavities with the common resonator. This correlation initiates an entanglement transfer from the intracavity photon-phonon entanglements to an intercavity photon-photon entanglement. Using numerical solutions, we show two distinct regimes of the optomechanical system, in which the indirect entanglement either builds up and eventually saturates or undergoes a death-and-revival cycle, after a time lapse for initiating the cooperative motion of the left and right cavity modes.

Field tuning the g factor in InAs nanowire double quantum dots.

PubMed

Schroer, M D; Petersson, K D; Jung, M; Petta, J R

2011-10-21

We study the effects of magnetic and electric fields on the g factors of spins confined in a two-electron InAs nanowire double quantum dot. Spin sensitive measurements are performed by monitoring the leakage current in the Pauli blockade regime. Rotations of single spins are driven using electric-dipole spin resonance. The g factors are extracted from the spin resonance condition as a function of the magnetic field direction, allowing determination of the full g tensor. Electric and magnetic field tuning can be used to maximize the g-factor difference and in some cases altogether quench the electric-dipole spin resonance response, allowing selective single spin control. © 2011 American Physical Society

Intermixing of InP-based quantum dots and application to micro-ring resonator wavelength-selective filter for photonic integrated devices

NASA Astrophysics Data System (ADS)

Matsumoto, Atsushi; Matsushita, Asuka; Takei, Yuki; Akahane, Kouichi; Matsushima, Yuichi; Ishikawa, Hiroshi; Utaka, Katsuyuki

2014-09-01

In this study, we investigated quantum dot intermixing (QDI) for InAs/InGaAlAs highly stacked QDs on an InP(311)B substrate with low-temperature annealing at 650 °C in order to realize integrated photonic devices with QDs and passive waveguides. In particular, we adopted the method of introducing point defects by ICP-RIE to realize a blue shift of the PL peak wavelength by about 150 nm. Moreover, we successfully fabricated double micro-ring resonators by QDI. The output power contrasts of the devices were found to be 9.0 and 8.6 dB for TE and TM modes, respectively.

Diffusion Tensor Imaging of Normal-Appearing White Matter as Biomarker for Radiation-Induced Late Delayed Cognitive Decline

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chapman, Christopher H., E-mail: chchap@umich.edu; Nagesh, Vijaya; Sundgren, Pia C.

Purpose: To determine whether early assessment of cerebral white matter degradation can predict late delayed cognitive decline after radiotherapy (RT). Methods and Materials: Ten patients undergoing conformal fractionated brain RT participated in a prospective diffusion tensor magnetic resonance imaging study. Magnetic resonance imaging studies were acquired before RT, at 3 and 6 weeks during RT, and 10, 30, and 78 weeks after starting RT. The diffusivity variables in the parahippocampal cingulum bundle and temporal lobe white matter were computed. A quality-of-life survey and neurocognitive function tests were administered before and after RT at the magnetic resonance imaging follow-up visits. Results:more » In both structures, longitudinal diffusivity ({lambda}{sub Double-Vertical-Line }) decreased and perpendicular diffusivity ({lambda}{sub Up-Tack }) increased after RT, with early changes correlating to later changes (p < .05). The radiation dose correlated with an increase in cingulum {lambda}{sub Up-Tack} at 3 weeks, and patients with >50% of cingula volume receiving >12 Gy had a greater increase in {lambda}{sub Up-Tack} at 3 and 6 weeks (p < .05). The post-RT changes in verbal recall scores correlated linearly with the late changes in cingulum {lambda}{sub Double-Vertical-Line} (30 weeks, p < .02). Using receiver operating characteristic curves, early cingulum {lambda}{sub Double-Vertical-Line} changes predicted for post-RT changes in verbal recall scores (3 and 6 weeks, p < .05). The neurocognitive test scores correlated significantly with the quality-of-life survey results. Conclusions: The correlation between early diffusivity changes in the parahippocampal cingulum and the late decline in verbal recall suggests that diffusion tensor imaging might be useful as a biomarker for predicting late delayed cognitive decline.« less

A Localized Surface Plasmon Resonance Sensor Using Double-Metal-Complex Nanostructures and a Review of Recent Approaches

PubMed Central

Ahn, Heesang; Song, Hyerin; Kim, Kyujung

2017-01-01

From active developments and applications of various devices to acquire outside and inside information and to operate based on feedback from that information, the sensor market is growing rapidly. In accordance to this trend, the surface plasmon resonance (SPR) sensor, an optical sensor, has been actively developed for high-sensitivity real-time detection. In this study, the fundamentals of SPR sensors and recent approaches for enhancing sensing performance are reported. In the section on the fundamentals of SPR sensors, a brief description of surface plasmon phenomena, SPR, SPR-based sensing applications, and several configuration types of SPR sensors are introduced. In addition, advanced nanotechnology- and nanofabrication-based techniques for improving the sensing performance of SPR sensors are proposed: (1) localized SPR (LSPR) using nanostructures or nanoparticles; (2) long-range SPR (LRSPR); and (3) double-metal-layer SPR sensors for additional performance improvements. Consequently, a high-sensitivity, high-biocompatibility SPR sensor method is suggested. Moreover, we briefly describe issues (miniaturization and communication technology integration) for future SPR sensors. PMID:29301238

Magnetophonon resonance in double quantum wells

NASA Astrophysics Data System (ADS)

Ploch, D.; Sheregii, E. M.; Marchewka, M.; Wozny, M.; Tomaka, G.

2009-05-01

The experimental results obtained for the magnetotransport in pulsed magnetic fields in the InGaAs/InAlAs double quantum well (DQW) structures of two different shapes of wells and different values of the electron density are reported. The magnetophonon resonance (MPR) was observed for both types of structures within the temperature range 77-125 K. Four kinds of LO phonons are taken into account to interpret the MPR oscillations in the DQW and a method of the Landau level calculation in the DQW is elaborated for this aim. The peculiarity of the MPR in the DQW is the large number of the Landau levels caused by SAS splitting of the electron states (splitting on the symmetric and anti-symmetric states) and the large number of the phonon assistance electron transitions between Landau levels. The significant role of the carrier statistics is shown too. The behavior of the electron states in the DQWs at comparably high temperatures has been studied using the MPR. It is shown that the Huang and Manasreh [Manasreh [Phys. Rev. B 54, 2044 (1996)] model involving screening of exchange interaction is confirmed.

Active structural acoustic control of noise transmission through double panel systems

NASA Astrophysics Data System (ADS)

Carneal, James P.; Fuller, Chris R.

1995-04-01

A preliminary parametric study of active control of sound transmission through double panel systems has been experimentally performed. The technique used is the active structural acoustic control (ASAC) approach where control inputs, in the form of piezoelectric actuators, were applied to the structure while the radiated pressure field was minimized. Results indicate the application of control inputs to the radiating panel resulted in greater transmission loss due to its direct effect on the nature of the structural-acoustic coupling between the radiating panel and the receiving chamber. Increased control performance was seen in a double panel system consisting of a stiffer radiating panel with a lower modal density. As expected, more effective control of a radiating panel excited on-resonance is achieved over one excited off-resonance. In general, the results validate the ASAC approach for double panel systems and demonstrate that it is possible to take advantage of double panel behavior to enhance control performance, although it is clear that further research must be done to understand the physics involved.

Methods to Determine the Deformation of the IRVE Hypersonic Inflatable Aerodynamic Decelerator

NASA Technical Reports Server (NTRS)

Young, William R.

2011-01-01

Small resonant targets used in conjunction with a microwave reflectometer to determine the deformation of the Hypersonic Inflatable Aerodynamic Decelerator (HIAD) during reentry are investigated. The reflectometer measures the distance to the targets and from this the HIAD deformation is determined. The HIAD is used by the Inflatable Reentry Vehicle Experiment (IRVE) which investigates the use of inflatable heat shields for atmospheric reentry. After several different microwave reflectometer systems were analyzed and compared it was determined that the most desirable for this application is the Frequency Doubling Target method.

Refraction index sensor based on phase resonances in a subwavelength structure with double period.

PubMed

Skigin, Diana C; Lester, Marcelo

2016-10-01

In this paper, we numerically demonstrate a refraction index sensor based on phase resonance excitation in a subwavelength-slit structure with a double period. The sensor consists of a metal layer with subwavelength slots arranged in a bi-periodic form, separated from a high refraction index medium. Between the metallic structure and the incident medium, a dielectric waveguide is formed whose refraction index is going to be determined. Variations in the refraction index of the waveguide are detected as shifts in the peaks of transmitted intensity originated by resonant modes supported by the compound metallic structure. At normal incidence, the spectral position of these resonant peaks exhibits a linear or a quadratic dependence with the refraction index, which permits us to obtain the unknown refraction index value with a high precision for a wide range of wavelengths. Since the operating principle of the sensor is due to the morphological resonances of the slits' structure, this device can be scaled to operate in different wavelength ranges while keeping similar characteristics.

Coupling a single electron spin to a microwave resonator: Part I: controlling transverse and longitudinal couplings

NASA Astrophysics Data System (ADS)

Lachance-Quirion, Dany; Beaudoin, Félix; Camirand Lemyre, Julien; Coish, William A.; Pioro-Ladrière, Michel

Novel quantum technologies can be combined within hybrid systems to benefit from the complementary capabilities of individual components. For example, microwave-frequency superconducting resonators are ideally suited to perform qubit readout and to mediate two-qubit gates, while spin qubits offer long coherence times and high-fidelity single-qubit gates. In this talk, we consider strong coupling between a microwave resonator and an electron-spin qubit in a double quantum dot due to an inhomogeneous magnetic field generated by a nearby nanomagnet.. Considering realistic parameters, we estimate spin-resonator couplings of order 1 MHz. Further, we show that the position of the double dot relative to the nanomagnet allows us to select between purely longitudinal and transverse couplings. While the transverse coupling may be used for quantum state transfer between the spin qubit and the resonator, the longitudinal coupling could be used in a new qubit readout scheme recently introduced for superconducting qubits.

Photon-Assisted Resonant Tunneling and 2-D Plasmon Modes in Double Quantum Wells in Intense Terahertz Electric Fields

NASA Astrophysics Data System (ADS)

Peralta, X. G.; Allen, S. J.; Lin, S. Y.; Simmons, J. A.; Blount, M. A.; Baca, W. E.

1998-03-01

We explore photon-assisted resonant tunneling in double quantum well systems in intense terahertz electric fields that have separately- contacted wells. We have two goals in mind: 1) increase the basic understanding of photon assisted tunneling in semiconductors and 2) assess the potential of this structure as a detector. We can control the tunneling current by varying the electron density of each 2D electron gas or by changing the relative separation of the Fermi levels. This allows us to prepare the system in such a way that photons of the appropriate energy may induce resonant tunneling, which is monitored by a change in conductance. We also examine the possible enhancement of the resonant tunneling by resonant excitations of acoustic plasmon modes. This work is supported by ONR, the U. S. Dept. of Energy under Contract DE-AC04-94AL85000 and Consejo Nacional de Ciencia y Tecnología, México.

Insights on energy selective contacts for thermal energy harvesting using double resonant tunneling contacts and numerical modeling

NASA Astrophysics Data System (ADS)

Julian, A.; Jehl, Z.; Miyashita, N.; Okada, Y.; Guillemoles, J.-F.

2016-12-01

Energy selective electrical contacts have been proposed as a way to approach ultimate efficiencies both for thermoelectric and photovoltaic devices as they allow a reduction of the entropy production during the energy conversion process. A self-consistent numerical model based on the transfer matrix approach in the effective mass and envelope function approximation has been developed to calculate the electronic properties of double resonant tunneling barriers used as energy selective contacts in hot carrier solar cells. It is found that the application of an external electric bias significantly degrades the electronic transmission of the structure, and thus the tunneling current in the current-voltage characteristic. This is due to a symmetry breaking which can be offset using finely tuned asymmetric double resonant tunneling barriers, leading to a full recovery of the tunneling current in our model. Moreover, we model the heterostructure using electrons temperature in the emitter higher than that of the lattice, providing insights on the interpretation of experimental devices functioning in hot carrier conditions, especially regarding the previously reported shift of the resonance peak (negative differential resistance), which we interpret as related to a shift in the hot electron distribution while the maximum remains at the conduction band edge of the emitter. Finally, experimental results are presented using asymmetric structure showing significantly improved resonant properties at room temperature with very sharp negative differential resistance.

Leakage and sweet spots in triple-quantum-dot spin qubits: A molecular-orbital study

NASA Astrophysics Data System (ADS)

Zhang, Chengxian; Yang, Xu-Chen; Wang, Xin

2018-04-01

A triple-quantum-dot system can be operated as either an exchange-only qubit or a resonant-exchange qubit. While it is generally believed that the decisive advantage of the resonant-exchange qubit is the suppression of charge noise because it is operated at a sweet spot, we show that the leakage is also an important factor. Through molecular-orbital-theoretic calculations, we show that when the system is operated in the exchange-only scheme, the leakage to states with double electron occupancy in quantum dots is severe when rotations around the axis 120∘ from z ̂ is performed. While this leakage can be reduced by either shrinking the dots or separating them further, the exchange interactions are also suppressed at the same time, making the gate operations unfavorably slow. When the system is operated as a resonant-exchange qubit, the leakage is three to five orders of magnitude smaller. We have also calculated the optimal detuning point which minimizes the leakage for the resonant-exchange qubit, and have found that although it does not coincide with the double sweet spot for the charge noise, they are rather close. Our results suggest that the resonant-exchange qubit has another advantage, that leakage can be greatly suppressed compared to the exchange-only qubit, and operating at the double sweet spot point should be optimal both for reducing charge noise and suppressing leakage.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pereyra, Pedro, E-mail: pereyrapedro@gmail.com; Mendoza-Figueroa, M. G.

Transport properties of electrons through biased double barrier semiconductor structures with finite transverse width w{sub y}, in the presence of a channel-mixing transverse electric field E{sub T} (along the y-axis), were studied. We solve the multichannel Schrödinger equation using the transfer matrix method and transport properties, like the conductance G and the transmission coefficients T{sub ij} have been evaluated as functions of the electrons' energy E and the transverse and longitudinal (bias) electric forces, f{sub T} and f{sub b}. We show that peak-suppression effects appear, due to the applied bias. Similarly, coherent interference of wave-guide states induced by the transversemore » field is obtained. We show also that the coherent interference of resonant wave-guide states gives rise to resonant conductance, which can be tuned to produce broad resonant peaks, implying operation frequencies of the order of 10 THz or larger.« less

In vivo resonant Raman measurement of macular carotenoid pigments in the young and the aging human retina

NASA Astrophysics Data System (ADS)

Gellermann, Werner; Ermakov, Igor V.; Ermakova, Maia R.; McClane, Robert W.; Zhao, Da-You; Bernstein, Paul S.

2002-06-01

We have used resonant Raman scattering spectroscopy as a novel, noninvasive, in vivo optical technique to measure the concentration of the macular carotenoid pigments lutein and zeaxanthin in the living human retina of young and elderly adults. Using a backscattering geometry and resonant molecular excitation in the visible wavelength range, we measure the Raman signals originating from the single- and double-bond stretch vibrations of the π-conjugated molecule's carbon backbone. The Raman signals scale linearly with carotenoid content, and the required laser excitation is well below safety limits for macular exposure. Furthermore, the signals decline significantly with increasing age in normal eyes. The Raman technique is objective and quantitative and may lead to a new method for rapid screening of carotenoid pigment levels in large populations at risk for vision loss from age-related macular degeneration, the leading cause of blindness in the elderly in the United States.

Pulsed-High Field/High-Frequency EPR Spectroscopy

NASA Astrophysics Data System (ADS)

Fuhs, Michael; Moebius, Klaus

Pulsed high-field/high-frequency electron paramagnetic resonance (EPR) spectroscopy is used to disentangle many kinds of different effects often obscured in continuous wave (cw) EPR spectra at lower magnetic fields/microwave frequencies. While the high magnetic field increases the resolution of G tensors and of nuclear Larmor frequencies, the high frequencies allow for higher time resolution for molecular dynamics as well as for transient paramagnetic intermediates studied with time-resolved EPR. Pulsed EPR methods are used for example for relaxation-time studies, and pulsed Electron Nuclear DOuble Resonance (ENDOR) is used to resolve unresolved hyperfine structure hidden in inhomogeneous linewidths. In the present article we introduce the basic concepts and selected applications to structure and mobility studies on electron transfer systems, reaction centers of photosynthesis as well as biomimetic models. The article concludes with an introduction to stochastic EPR which makes use of an other concept for investigating resonance systems in order to increase the excitation bandwidth of pulsed EPR. The limited excitation bandwidth of pulses at high frequency is one of the main limitations which, so far, made Fourier transform methods hardly feasible.

Inter-spin distance determination using L-band (1-2 GHz) non-adiabatic rapid sweep electron paramagnetic resonance (NARS EPR)

PubMed Central

Kittell, Aaron W.; Hustedt, Eric J.; Hyde, James S.

2014-01-01

Site-directed spin-labeling electron paramagnetic resonance (SDSL EPR) provides insight into the local structure and motion of a spin probe strategically attached to a molecule. When a second spin is introduced to the system, macromolecular information can be obtained through measurement of inter-spin distances either by continuous wave (CW) or pulsed electron double resonance (ELDOR) techniques. If both methodologies are considered, inter-spin distances of 8 to 80 Å can be experimentally determined. However, there exists a region at the upper limit of the conventional X-band (9.5 GHz) CW technique and the lower limit of the four-pulse double electron-electron resonance (DEER) experiment where neither method is particularly reliable. The work presented here utilizes L-band (1.9 GHz) in combination with non-adiabatic rapid sweep (NARS) EPR to address this opportunity by increasing the upper limit of the CW technique. Because L-band linewidths are three to seven times narrower than those at X-band, dipolar broadenings that are small relative to the X-band inhomogeneous linewidth become observable, but the signal loss due to the frequency dependence of the Boltzmann factor, has made L-band especially challenging. NARS has been shown to increase sensitivity by a factor of five, and overcomes much of this loss, making L-band distance determination more feasible [1]. Two different systems are presented and distances of 18–30 Å have been experimentally determined at physiologically relevant temperatures. Measurements are in excellent agreement with a helical model and values determined by DEER. PMID:22750251

Compact wideband filter element-based on complementary split-ring resonators

NASA Astrophysics Data System (ADS)

Horestani, Ali K.; Shaterian, Zahra; Withayachumnankul, Withawat; Fumeaux, Christophe; Al-Sarawi, Said; Abbott, Derek

2011-12-01

A double resonance defected ground structure is proposed as a filter element. The structure involves a transmission line loaded with complementary split ring resonators embedded in a dumbbell shape defected ground structure. By using a parametric study, it is demonstrated that the two resonance frequencies can be independently tuned. Therefore the structure can be used for different applications such as dual bandstop filters and wide bandstop filters.

Signatures of single-photon interaction between two quantum dots located in different cavities of a weakly coupled double microdisk structure

NASA Astrophysics Data System (ADS)

Seyfferle, S.; Hargart, F.; Jetter, M.; Hu, E.; Michler, P.

2018-01-01

We report on the radiative interaction of two single quantum dots (QDs) each in a separate InP/GaInP-based microdisk cavity via resonant whispering gallery modes. The investigations are based on as-fabricated coupled disk modes. We apply optical spectroscopy involving a 4 f setup, as well as mode-selective real-space imaging and photoluminescence mapping to discern single QDs coupled to a resonant microdisk mode. Excitation of one disk of the double cavity structure and detecting photoluminescence from the other yields proof of single-photon emission of a QD excited by incoherent energy transfer from one disk to the other via a mode in the weak-coupling regime. Finally, we present evidence of photons emitted by a QD in one disk that are transferred to the other disk by a resonant mode and are subsequently resonantly scattered by another QD.

Inner- and outer-wall sorting of double-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Li, Han; Gordeev, Georgy; Wasserroth, Sören; Chakravadhanula, Venkata Sai Kiran; Neelakandhan, Shyam Kumar Chethala; Hennrich, Frank; Jorio, Ado; Reich, Stephanie; Krupke, Ralph; Flavel, Benjamin Scott

2017-12-01

Double-walled carbon nanotubes (DWCNTs) consist of two coaxially aligned single-walled carbon nanotubes (SWCNTs), and previous sorting methods only achieved outer-wall electronic-type selectivity. Here, a separation technique capable of sorting DWCNTs by semiconducting (S) or metallic (M) inner- and outer-wall electronic type is presented. Electronic coupling between the inner and outer wall is used to alter the surfactant coating around each of the DWCNT types, and aqueous gel permeation is used to separate them. Aqueous methods are used to remove SWCNT species from the raw material and prepare enriched DWCNT fractions. The enriched DWCNT fractions are then transferred into either chlorobenzene or toluene using the copolymer PFO-BPy to yield the four inner@outer combinations of M@M, M@S, S@M and S@S. The high purity of the resulting fractions is verified by absorption measurements, transmission electron microscopy, atomic force microscopy, resonance Raman mapping and high-density field-effect transistor devices.

Inner- and outer-wall sorting of double-walled carbon nanotubes.

PubMed

Li, Han; Gordeev, Georgy; Wasserroth, Sören; Chakravadhanula, Venkata Sai Kiran; Neelakandhan, Shyam Kumar Chethala; Hennrich, Frank; Jorio, Ado; Reich, Stephanie; Krupke, Ralph; Flavel, Benjamin Scott

2017-12-01

Double-walled carbon nanotubes (DWCNTs) consist of two coaxially aligned single-walled carbon nanotubes (SWCNTs), and previous sorting methods only achieved outer-wall electronic-type selectivity. Here, a separation technique capable of sorting DWCNTs by semiconducting (S) or metallic (M) inner- and outer-wall electronic type is presented. Electronic coupling between the inner and outer wall is used to alter the surfactant coating around each of the DWCNT types, and aqueous gel permeation is used to separate them. Aqueous methods are used to remove SWCNT species from the raw material and prepare enriched DWCNT fractions. The enriched DWCNT fractions are then transferred into either chlorobenzene or toluene using the copolymer PFO-BPy to yield the four inner@outer combinations of M@M, M@S, S@M and S@S. The high purity of the resulting fractions is verified by absorption measurements, transmission electron microscopy, atomic force microscopy, resonance Raman mapping and high-density field-effect transistor devices.

Experimental Potential Energy Curve for the 43 Π Electronic State of NaCs

NASA Astrophysics Data System (ADS)

Steely, Andrew; Cooper, Hannah; Zain, Hareem; Whipp, Ciara; Faust, Carl; Kortyna, Andrew; Huennekens, John

2017-04-01

We present results from experimental studies of the 43 Π electronic state of the NaCs molecule. This electronic state is interesting in that its potential energy curve likely exhibits a double minimum. As a result, interference effects are observed in the resolved bound-free fluorescence spectra. The optical-optical double resonance method was used to obtain Doppler-free excitation spectra for the 43 Π state. This dataset of measured level energies was expanded largely by observing fluorescence from levels populated by collisions. To aid in level assignments, simulations of resolved bound-free fluorescence spectra were calculated using the BCONT program (R. J. Le Roy, University of Waterloo). Spectroscopic constants were determined to summarize data belonging to inner well, outer well, and above barrier regions of the electronic state. Current work focuses on using the IPA method to construct an experimental potential energy curve. Work supported by NSF and Susquehanna University.

High resolution neutron Larmor diffraction using superconducting magnetic Wollaston prisms

DOE PAGES

Li, Fankang; Feng, Hao; Thaler, Alexander N.; ...

2017-04-13

The neutron Larmor diffraction technique has been implemented using superconducting magnetic Wollaston prisms in both single-arm and double-arm configurations. Successful measurements of the coefficient of thermal expansion of a single-crystal copper sample demonstrates that the method works as expected. Our experiment involves a new method of tuning by varying the magnetic field configurations in the device and the tuning results agree well with previous measurements. The difference between single-arm and double-arm configurations has been investigated experimentally. Here, we conclude that this measurement benchmarks the applications of magnetic Wollaston prisms in Larmor diffraction and shows in principle that the setup canmore » be used for inelastic phonon line-width measurements. The achievable resolution for Larmor diffraction is comparable to that using Neutron Resonance Spin Echo (NRSE) coils. Furthermore, the use of superconducting materials in the prisms allows high neutron polarization and transmission efficiency to be achieved.« less

Method of phase space beam dilution utilizing bounded chaos generated by rf phase modulation

DOE PAGES

Pham, Alfonse N.; Lee, S. Y.; Ng, K. Y.

2015-12-10

This paper explores the physics of chaos in a localized phase-space region produced by rf phase modulation applied to a double rf system. The study can be exploited to produce rapid particle bunch broadening exhibiting longitudinal particle distribution uniformity. Hamiltonian models and particle-tracking simulations are introduced to understand the mechanism and applicability of controlled particle diffusion. When phase modulation is applied to the double rf system, regions of localized chaos are produced through the disruption and overlapping of parametric resonant islands and configured to be bounded by well-behaved invariant tori to prevent particle loss. The condition of chaoticity and themore » degree of particle dilution can be controlled by the rf parameters. As a result, the method has applications in alleviating adverse space-charge effects in high-intensity beams, particle bunch distribution uniformization, and industrial radiation-effects experiments.« less

Double plasma resonance instability as a source of solar zebra emission

NASA Astrophysics Data System (ADS)

Benáček, J.; Karlický, M.

2018-03-01

Context. The double plasma resonance (DPR) instability plays a basic role in the generation of solar radio zebras. In the plasma, consisting of the loss-cone type distribution of hot electrons and much denser and colder background plasma, this instability generates the upper-hybrid waves, which are then transformed into the electromagnetic waves and observed as radio zebras. Aims: In the present paper we numerically study the double plasma resonance instability from the point of view of the zebra interpretation. Methods: We use a 3-dimensional electromagnetic particle-in-cell (3D PIC) relativistic model. We use this model in two versions: (a) a spatially extended "multi-mode" model and (b) a spatially limited "specific-mode" model. While the multi-mode model is used for detailed computations and verifications of the results obtained by the "specific-mode" model, the specific-mode model is used for computations in a broad range of model parameters, which considerably save computational time. For an analysis of the computational results, we developed software tools in Python. Results: First using the multi-mode model, we study details of the double plasma resonance instability. We show how the distribution function of hot electrons changes during this instability. Then we show that there is a very good agreement between results obtained by the multi-mode and specific-mode models, which is caused by a dominance of the wave with the maximal growth rate. Therefore, for computations in a broad range of model parameters, we use the specific-mode model. We compute the maximal growth rates of the double plasma resonance instability with a dependence on the ratio between the upper-hybrid ωUH and electron-cyclotron ωce frequency. We vary temperatures of both the hot and background plasma components and study their effects on the resulting growth rates. The results are compared with the analytical ones. We find a very good agreement between numerical and analytical growth rates. We also compute saturation energies of the upper-hybrid waves in a very broad range of parameters. We find that the saturation energies of the upper-hybrid waves show maxima and minima at almost the same values of ωUH/ωce as the growth rates, but with a higher contrast between them than the growth rate maxima and minima. The contrast between saturation energy maxima and minima increases when the temperature of hot electrons increases. Furthermore, we find that the saturation energy of the upper-hybrid waves is proportional to the density of hot electrons. The maximum saturated energy can be up to one percent of the kinetic energy of hot electrons. Finally we find that the saturation energy maxima in the interval of ωUH/ωce = 3-18 decrease according to the exponential function. All these findings can be used in the interpretation of solar radio zebras.

Detection of single electron spin resonance in a double quantum dota)

NASA Astrophysics Data System (ADS)

Koppens, F. H. L.; Buizert, C.; Vink, I. T.; Nowack, K. C.; Meunier, T.; Kouwenhoven, L. P.; Vandersypen, L. M. K.

2007-04-01

Spin-dependent transport measurements through a double quantum dot are a valuable tool for detecting both the coherent evolution of the spin state of a single electron, as well as the hybridization of two-electron spin states. In this article, we discuss a model that describes the transport cycle in this regime, including the effects of an oscillating magnetic field (causing electron spin resonance) and the effective nuclear fields on the spin states in the two dots. We numerically calculate the current flow due to the induced spin flips via electron spin resonance, and we study the detector efficiency for a range of parameters. The experimental data are compared with the model and we find a reasonable agreement.

Solid State Research

DTIC Science & Technology

1987-01-07

Excimer-Laser Projection Lithography 38 4.5 Observation of Millimeter-Wave Oscillations from Resonant- Tunneling Diodes and Some Theroretical...and SIMOX Circuits 32 4-1 Resonant Tunneling Diode Parameters 41 XI INTRODUCTION 1. SOLID STATE DEVICE RESEARCH Optoelectronic switches have...radiation and reflective optics. Oscillation frequencies as high as 56 GHz have been observed from resonant- tunneling double- barrier diodes. Recent

[Prostate biopsy under magnetic resonance imaging guidance].

PubMed

Kuplevatskiy, V I; CherkashiN, M A; Roshchin, D A; Berezina, N A; Vorob'ev, N A

2016-01-01

Prostate cancer (PC) is one of the most important problems in modern oncology. According to statistical data, PC ranks second in the cancer morbidity structure in the Russian Federation and developed countries and its prevalence has been progressively increasing over the past decade. A need for early diagnosis and maximally accurate morphological verification of the diagnosis in difficult clinical cases (inconvenient tumor location for standard transrectal biopsy; gland scarring changes concurrent with prostatitis and hemorrhage; threshold values of prostate-specific antigen with unclear changes in its doubling per unit time; suspicion of biochemical recurrence or clinical tumor progression after special treatment) leads to revised diagnostic algorithms and clinically introduced new high-tech invasive diagnostic methods. This paper gives the first analysis of literature data on Russian practice using one of the new methods to verify prostate cancer (transrectal prostate cancer under magnetic resonance imaging (MRI) guidance). The have sought the 1995-2015 data in the MEDLINE and Pubmed.

Controlling chaos-assisted directed transport via quantum resonance.

PubMed

Tan, Jintao; Zou, Mingliang; Luo, Yunrong; Hai, Wenhua

2016-06-01

We report on the first demonstration of chaos-assisted directed transport of a quantum particle held in an amplitude-modulated and tilted optical lattice, through a resonance-induced double-mean displacement relating to the true classically chaotic orbits. The transport velocity is controlled by the driving amplitude and the sign of tilt, and also depends on the phase of the initial state. The chaos-assisted transport feature can be verified experimentally by using a source of single atoms to detect the double-mean displacement one by one, and can be extended to different scientific fields.

Mims electron-nuclear double resonance in LiYF4:Ce3+ crystal

NASA Astrophysics Data System (ADS)

Gafurov, M.; Mamin, G.; Kurkin, I.; Orlinskii, S.

2018-05-01

We report the observation of the pulsed electron-nuclear double resonance (ENDOR) spectra from 19F and 7Li nuclei on impurity Ce3+ ions in LiYF4 crystal. The resolved structure from the nearby and remote nuclei in spectra is observed. The outcome shows that LiYF4:Ce3+ system can be exploited as a convenient matrix for performing spin manipulations and adjusting quantum computation protocols while ENDOR technique is usable for the investigation of electron-nuclear interaction with all the nuclei of the system.

Controlling chaos-assisted directed transport via quantum resonance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Jintao; Zou, Mingliang; Luo, Yunrong

2016-06-15

We report on the first demonstration of chaos-assisted directed transport of a quantum particle held in an amplitude-modulated and tilted optical lattice, through a resonance-induced double-mean displacement relating to the true classically chaotic orbits. The transport velocity is controlled by the driving amplitude and the sign of tilt, and also depends on the phase of the initial state. The chaos-assisted transport feature can be verified experimentally by using a source of single atoms to detect the double-mean displacement one by one, and can be extended to different scientific fields.

Spin bottleneck in resonant tunneling through double quantum dots with different Zeeman splittings.

PubMed

Huang, S M; Tokura, Y; Akimoto, H; Kono, K; Lin, J J; Tarucha, S; Ono, K

2010-04-02

We investigated the electron transport property of the InGaAs/GaAs double quantum dots, the electron g factors of which are different from each other. We found that in a magnetic field, the resonant tunneling is suppressed even if one of the Zeeman sublevels is aligned. This is because the other misaligned Zeeman sublevels limit the total current. A finite broadening of the misaligned sublevel partially relieves this bottleneck effect, and the maximum current is reached when interdot detuning is half the Zeeman energy difference.

Resonant pair tunneling in double quantum dots.

PubMed

Sela, Eran; Affleck, Ian

2009-08-21

We present exact results on the nonequilibrium current fluctuations for 2 quantum dots in series throughout a crossover from non-Fermi liquid to Fermi liquid behavior described by the 2 impurity Kondo model. The result corresponds to resonant tunneling of carriers of charge 2e for a critical interimpurity coupling. At low energy scales, the result can be understood from a Fermi liquid approach that we develop and use to also study nonequilibrium transport in an alternative double dot realization of the 2 impurity Kondo model under current experimental study.

Detection of cerebral NAD+ in humans at 7T.

PubMed

de Graaf, Robin A; De Feyter, Henk M; Brown, Peter B; Nixon, Terence W; Rothman, Douglas L; Behar, Kevin L

2017-09-01

To develop 1 H-based MR detection of nicotinamide adenine dinucleotide (NAD + ) in the human brain at 7T and validate the 1 H results with NAD + detection based on 31 P-MRS. 1 H-MR detection of NAD + was achieved with a one-dimensional double-spin-echo method on a slice parallel to the surface coil transceiver. Perturbation of the water resonance was avoided through the use of frequency-selective excitation. 31 P-MR detection of NAD + was performed with an unlocalized pulse-acquire sequence. Both 1 H- and 31 P-MRS allowed the detection of NAD + signals on every subject in 16 min. Spectral fitting provided an NAD + concentration of 107 ± 28 μM for 1 H-MRS and 367 ± 78 μM and 312 ± 65 μM for 31 P-MRS when uridine diphosphate glucose (UDPG) was excluded and included, respectively, as an overlapping signal. NAD + detection by 1 H-MRS is a simple method that comes at the price of reduced NMR visibility. NAD + detection by 31 P-MRS has near-complete NMR visibility, but it is complicated by spectral overlap with NADH and UDPG. Overall, the 1 H- and 31 P-MR methods both provide exciting opportunities to study NAD + metabolism on human brain in vivo. © 2016 International Society for Magnetic Resonance in Medicine. Magn Reson Med 78:828-835, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Two-colour dip spectroscopy of jet-cooled molecules

NASA Astrophysics Data System (ADS)

Ito, Mitsuo

In optical-optical double resonance spectroscopy, the resonance transition from an intermediate state to a final state can be detected by a dip of the signal (fluorescence or ion) associated with the intermediate state. This method probing the signal of the intermediate state may be called `two-colour dip spectroscopy'. Various kinds of two-colour dip spectroscopy such as two-colour fluorescence/ion dip spectroscopy, two-colour ionization dip spectroscopy employing stimulated emission, population labelling spectroscopy and mass-selected ion dip spectroscopy with dissociation were briefly described, paying special attention to their characteristics in excitation, detection and application. They were extensively and successfully applied to jet-cooled large molecules and provided us with new useful information on the energy and dynamics of excited molecules.

Steady-state and dynamic characteristics of a 20-kHz spacecraft power system - Control of harmonic resonance

NASA Technical Reports Server (NTRS)

Wasynczuk, O.; Krause, P. C.; Biess, J. J.; Kapustka, R.

1990-01-01

A detailed computer simulation was used to illustrate the steady-state and dynamic operating characteristics of a 20-kHz resonant spacecraft power system. The simulated system consists of a parallel-connected set of DC-inductor resonant inverters (drivers), a 440-V cable, a node transformer, a 220-V cable, and a transformer-rectifier-filter (TRF) AC-to-DC receiver load. Also included in the system are a 1-kW 0.8-pf RL load and a double-LC filter connected at the receiving end of the 20-kHz AC system. The detailed computer simulation was used to illustrate the normal steady-state operating characteristics and the dynamic system performance following, for example, TRF startup. It is shown that without any filtering the given system exhibits harmonic resonances due to an interaction between the switching of the source and/or load converters and the AC system. However, the double-LC filter at the receiving-end of the AC system and harmonic traps connected in series with each of the drivers significantly reduce the harmonic distortion of the 20-kHz bus voltage. Significant additional improvement in the waveform quality can be achieved by including a double-LC filter with each driver.

A dual-wavelength overlapping resonance Rayleigh scattering method for the determination of chondroitin sulfate with nile blue sulfate

NASA Astrophysics Data System (ADS)

Cui, Zhiping; Hu, Xiaoli; Liu, Shaopu; Liu, Zhongfang

2011-12-01

A dual-wavelength overlapping resonance Rayleigh scattering (DWO-RRS) method was developed to detect chondroitin sulfate (CS) with nile blue sulfate (NBS). At pH 3.0-4.0 Britton-Robinson (BR) buffer medium, CS interacted with NBS to form an ion-association complex. As a result, the new spectra of resonance Rayleigh scattering (RRS), second order scattering (SOS) and frequence doubling scattering (FDS) appeared and their intensities were enhanced greatly. Their maximum wavelengths were located at 303 nm (RRS), 362 nm (RRS), 588 nm (SOS) and 350 nm (FDS), respectively. The scattering intensities of the three methods were proportional to the concentration of CS in certain ranges. The methods had high sensitivity and the detection limits were between 1.5 and 7.1 ng mL -1. The DWO-RRS method had the highest sensitivity with the detection limit being 1.5 ng mL -1. The characteristics of the spectra and optimal reaction conditions of RRS method were investigated. The effects of coexistent substances on the determination of CS were evaluated. Owing to the high sensitivity, RRS method had been applied to the determination of CS in eye drops with satisfactory results. The recovery range was between 99.4% and 104.6% and the relative standard deviation (RSD) was between 0.4% and 0.8%. In addition, the reasons for RRS enhancement were discussed and the shape of ion-association complex was characterized by atomic force microscopy (AFM).

Resonant dielectric metamaterials

DOEpatents

Loui, Hung; Carroll, James; Clem, Paul G; Sinclair, Michael B

2014-12-02

A resonant dielectric metamaterial comprises a first and a second set of dielectric scattering particles (e.g., spheres) having different permittivities arranged in a cubic array. The array can be an ordered or randomized array of particles. The resonant dielectric metamaterials are low-loss 3D isotropic materials with negative permittivity and permeability. Such isotropic double negative materials offer polarization and direction independent electromagnetic wave propagation.

Broadband excitation in nuclear magnetic resonance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tycko, Robert

1984-10-01

Theoretical methods for designing sequences of radio frequency (rf) radiation pulses for broadband excitation of spin systems in nuclear magnetic resonance (NMR) are described. The sequences excite spins uniformly over large ranges of resonant frequencies arising from static magnetic field inhomogeneity, chemical shift differences, or spin couplings, or over large ranges of rf field amplitudes. Specific sequences for creating a population inversion or transverse magnetization are derived and demonstrated experimentally in liquid and solid state NMR. One approach to broadband excitation is based on principles of coherent averaging theory. A general formalism for deriving pulse sequences is given, along withmore » computational methods for specific cases. This approach leads to sequences that produce strictly constant transformations of a spin system. The importance of this feature in NMR applications is discussed. A second approach to broadband excitation makes use of iterative schemes, i.e. sets of operations that are applied repetitively to a given initial pulse sequences, generating a series of increasingly complex sequences with increasingly desirable properties. A general mathematical framework for analyzing iterative schemes is developed. An iterative scheme is treated as a function that acts on a space of operators corresponding to the transformations produced by all possible pulse sequences. The fixed points of the function and the stability of the fixed points are shown to determine the essential behavior of the scheme. Iterative schemes for broadband population inversion are treated in detail. Algebraic and numerical methods for performing the mathematical analysis are presented. Two additional topics are treated. The first is the construction of sequences for uniform excitation of double-quantum coherence and for uniform polarization transfer over a range of spin couplings. Double-quantum excitation sequences are demonstrated in a liquid crystal system. The second additional topic is the construction of iterative schemes for narrowband population inversion. The use of sequences that invert spin populations only over a narrow range of rf field amplitudes to spatially localize NMR signals in an rf field gradient is discussed.« less

Wavelength division multiplexed and double-port pumped time-bin entangled photon pair generation using Si ring resonator.

PubMed

Fujiwara, Mikio; Wakabayashi, Ryota; Sasaki, Masahide; Takeoka, Masahiro

2017-02-20

We report a wavelength division multiplexed time-bin entangled photon pair source in telecom wavelength using a 10 μm radius Si ring resonator. This compact resonator has two add ports and two drop ports. By pumping one add port by a continuous laser, we demonstrate an efficient generation of two-wavelength division multiplexed time-bin entangled photon pairs in the telecom C-band, which come out of one drop port, and are then split into the signal and idler photons via a wavelength filter. The resonator structure enhances four-wave mixing for pair generation. Moreover, we demonstrate the double-port pumping where two counter propagating pump lights are injected to generate entanglement from the two drop ports simultaneously. We successfully observe the highly entangled outputs from both two drop ports. Surprisingly, the count rate at each drop port is even increased by twice that of the single-port pumping. Possible mechanisms of this observation are discussed. Our technique allows for the efficient use of the Si ring resonator and widens its functionality for variety of applications.

Intervalley double resonance processes in MoS2

NASA Astrophysics Data System (ADS)

Wang, Yuanxi; Carvalho, Bruno; Malard, Leandro; Fantini, Cristiano; Crespi, Vincent; Pimenta, Marcos

Intervalley scattering plays a significant role in electronic energy dissipation in semiconductors. We investigate the intervalley scattering of monolayer and few-layer MoS2, by combining density functional theory calculations and resonant Raman spectroscopy probed by up to 20 laser excitation energies. We observe that two Raman peaks within 420-460 cm-1 are dispersive over a small range of laser energy, a clear signature of second-order processes involving intervalley scattering. Both modes involve LA and TA phonons at or near the K point. A third Raman peak at 466 cm-1 shows a strong intensity dependence on the layer number and is assigned 2LA(M). Our results invalidate previous Raman peak assignment proposals and open up a better understanding of double resonance processes in transition metal dichalcogenides.

On the tunneling time of ultracold atoms through a system of two mazer cavities.

PubMed

Badshah, Fazal; Ge, Guo-Qin; Irfan, Muhammad; Qamar, Sajid; Qamar, Shahid

2018-01-30

We study the resonant tunneling of ultraslow atoms through a system of high quality microwave cavities. We find that the phase tunneling time across the two coupled cavities exhibits more frequent resonances as compared to the single cavity interaction. The increased resonances are instrumental in the display of an alternate sub and superclassical character of the tunneling time along the momentum axis with increasing energies of the incident slow atoms. Here, the intercavity separation appears as an additional controlling parameter of the system that provides an efficient control of the superclassical behavior of the phase tunneling time. Further, we find that the phase time characteristics through two cavity system has the combined features of the tunneling through a double barrier and a double well arrangements.

Propagation of spiking regularity and double coherence resonance in feedforward networks.

PubMed

Men, Cong; Wang, Jiang; Qin, Ying-Mei; Deng, Bin; Tsang, Kai-Ming; Chan, Wai-Lok

2012-03-01

We investigate the propagation of spiking regularity in noisy feedforward networks (FFNs) based on FitzHugh-Nagumo neuron model systematically. It is found that noise could modulate the transmission of firing rate and spiking regularity. Noise-induced synchronization and synfire-enhanced coherence resonance are also observed when signals propagate in noisy multilayer networks. It is interesting that double coherence resonance (DCR) with the combination of synaptic input correlation and noise intensity is finally attained after the processing layer by layer in FFNs. Furthermore, inhibitory connections also play essential roles in shaping DCR phenomena. Several properties of the neuronal network such as noise intensity, correlation of synaptic inputs, and inhibitory connections can serve as control parameters in modulating both rate coding and the order of temporal coding.

Low temperature probe for dynamic nuclear polarization and multiple-pulse solid-state NMR.

PubMed

Cho, HyungJoon; Baugh, Jonathan; Ryan, Colm A; Cory, David G; Ramanathan, Chandrasekhar

2007-08-01

Here, we describe the design and performance characteristics of a low temperature probe for dynamic nuclear polarization (DNP) experiments, which is compatible with demanding multiple-pulse experiments. The competing goals of a high-Q microwave cavity to achieve large DNP enhancements and a high efficiency NMR circuit for multiple-pulse control lead to inevitable engineering tradeoffs. We have designed two probes-one with a single-resonance RF circuit and a horn-mirror cavity configuration for the microwaves and a second with a double-resonance RF circuit and a double-horn cavity configuration. The advantage of the design is that the sample is in vacuum, the RF circuits are locally tuned, and the microwave resonator has a large internal volume that is compatible with the use of RF and gradient coils.

7.5 W blue light generation at 452 nm by internal frequency doubling of a continuous-wave Nd-doped fiber laser.

PubMed

Leconte, Baptiste; Gilles, Hervé; Robin, Thierry; Cadier, Benoit; Laroche, Mathieu

2018-04-16

We present the first frequency-doubled neodymium-doped fiber laser generating multi-watt CW power near 450 nm. A bow-tie resonator incorporating a LBO nonlinear crystal is integrated within a Nd-doped fiber laser emitting near 900 nm. This scheme achieves an IR to blue conversion efficiency close to 55% without any active control of the internal resonant cavity. As a result, up to 7.5 W of linearly-polarized blue power is generated, with beam quality factors M x 2 ~1.0 and M y 2 ~1.5. A simple numerical model has been developed to optimize and analyse the IR to blue conversion efficiency in the resonant cavity. Performance limitations and prospects for further improvements are discussed.

Broadband reflective multi-polarization converter based on single-layer double-L-shaped metasurface

NASA Astrophysics Data System (ADS)

Mao, Chenyang; Yang, Yang; He, Xiaoxiang; Zheng, Jingming; Zhou, Chun

2017-12-01

In this paper, a broadband reflective multi-polarization converter based on single-layer double-L-shaped metasurface is proposed. The proposed metasurface can effectively convert linear-polarized (TE/TM) incident wave into the reflected wave with three different polarizations within the frequency bands of 5.5-22.75 GHz. Based on the electric and magnetic resonant features of the double-L-shaped structure, the proposed metasurface can convert linearly polarized waves into cross-polarized waves at three resonant frequency bands. Furthermore, the incident linearly polarized waves can be effectively converted into left/right handed circular-polarized (LHCP and RHCP) waves at other four non-resonance frequency bands. Thus, the proposed metasurface can be regarded as a seven-band multi-polarization converter. The prototype of the proposed polarization converter is analyzed and measured. Both simulated and measured results show the 3-dB axis ratio bandwidth of circular polarization bands and the high polarization conversion efficiency of cross-polarization bands when the incident wave changes from 0° to 30° at both TE and TM modes.

Transition from an optical precursor in coupled-resonator-induced transparency to coherent energy exchange in Autler-Townes splitting

NASA Astrophysics Data System (ADS)

Oishi, Tohru; Suzuki, Ryuta; Talukder, Aminul I.; Tomita, Makoto

2013-08-01

We investigated the transient responses of coupled optical resonators, after they were injected with square modulated temporal pulses. A sharp spike, attributed to the optical precursor in coupled-resonator-induced transparency, appeared when the coupling between the resonators was weak. As the coupling strength increased, the resonance spectrum developed clearly separated double dips of Autler-Townes splitting, and the precursor spike transformed into an oscillatory structure. These temporal oscillations were attributed to the coherent energy exchange between two resonators. Theoretical calculations were in good agreement with the experimental observations.

Solvent signal suppression for high-resolution MAS-DNP

NASA Astrophysics Data System (ADS)

Lee, Daniel; Chaudhari, Sachin R.; De Paëpe, Gaël

2017-05-01

Dynamic nuclear polarization (DNP) has become a powerful tool to substantially increase the sensitivity of high-field magic angle spinning (MAS) solid-state NMR experiments. The addition of dissolved hyperpolarizing agents usually results in the presence of solvent signals that can overlap and obscure those of interest from the analyte. Here, two methods are proposed to suppress DNP solvent signals: a Forced Echo Dephasing experiment (FEDex) and TRAnsfer of Populations in DOuble Resonance Echo Dephasing (TRAPDORED) NMR. These methods reintroduce a heteronuclear dipolar interaction that is specific to the solvent, thereby forcing a dephasing of recoupled solvent spins and leaving acquired NMR spectra free of associated resonance overlap with the analyte. The potency of these methods is demonstrated on sample types common to MAS-DNP experiments, namely a frozen solution (of L-proline) and a powdered solid (progesterone), both containing deuterated glycerol as a DNP solvent. The proposed methods are efficient, simple to implement, compatible with other NMR experiments, and extendable past spectral editing for just DNP solvents. The sensitivity gains from MAS-DNP in conjunction with FEDex or TRAPDORED then permits rapid and uninterrupted sample analysis.

On the Chaotic Vibrations of Electrostatically Actuated Arch Micro/Nano Resonators: A Parametric Study

NASA Astrophysics Data System (ADS)

Tajaddodianfar, Farid; Hairi Yazdi, Mohammad Reza; Pishkenari, Hossein Nejat

Motivated by specific applications, electrostatically actuated bistable arch shaped micro-nano resonators have attracted growing attention in the research community in recent years. Nevertheless, some issues relating to their nonlinear dynamics, including the possibility of chaos, are still not well known. In this paper, we investigate the chaotic vibrations of a bistable resonator comprised of a double clamped initially curved microbeam under combined harmonic AC and static DC distributed electrostatic actuation. A reduced order equation obtained by the application of the Galerkin method to the nonlinear partial differential equation of motion, given in the framework of Euler-Bernoulli beam theory, is used for the investigation in this paper. We numerically integrate the obtained equation to study the chaotic vibrations of the proposed system. Moreover, we investigate the effects of various parameters including the arch curvature, the actuation parameters and the quality factor of the resonator, which are effective in the formation of both static and dynamic behaviors of the system. Using appropriate numerical tools, including Poincaré maps, bifurcation diagrams, Fourier spectrum and Lyapunov exponents we scrutinize the effects of various parameters on the formation of chaotic regions in the parametric space of the resonator. Results of this work provide better insight into the problem of nonlinear dynamics of the investigated family of bistable micro/nano resonators, and facilitate the design of arch resonators for applications such as filters.

Efficient double-quenching of electrochemiluminescence from CdS:Eu QDs by hemin-graphene-Au nanorods ternary composite for ultrasensitive immunoassay

PubMed Central

Liu, Jing; Cui, Meirong; Zhou, Hong; Zhang, Shusheng

2016-01-01

A novel ternary composite of hemin-graphene-Au nanorods (H-RGO-Au NRs) with high electrocatalytic activity was synthesized by a simple method. And this ternary composite was firstly used in construction of electrochemiluminescence (ECL) immunosensor due to its double-quenching effect of quantum dots (QDs). Based on the high electrocatalytic activity of ternary complexes for the reduction of H2O2 which acted as the coreactant of QDs-based ECL, as a result, the ECL intensity of QDs decreased. Besides, due to the ECL resonance energy transfer (ECL-RET) strategy between the large amount of Au nanorods (Au NRs) on the ternary composite surface and the CdS:Eu QDs, the ECL intensity of QDs was further quenched. Based on the double-quenching effect, a novel ultrasensitive ECL immunoassay method for detection of carcinoembryonic antigen (CEA) which is used as a model biomarker analyte was proposed. The designed immunoassay method showed a linear range from 0.01 pg mL−1 to 1.0 ng mL−1 with a detection limit of 0.01 pg mL−1. The method showing low detection limit, good stability and acceptable fabrication reproducibility, provided a new approach for ECL immunoassay sensing and significant prospect for practical application. PMID:27460868

Characterization of macromolecular baseline of human brain using metabolite cycled semi-LASER at 9.4T.

PubMed

Giapitzakis, Ioannis-Angelos; Avdievich, Nikolai; Henning, Anke

2018-08-01

Macromolecular resonances (MM) arise mainly from cytosolic proteins and overlap with metabolites, influencing metabolite quantification. Macromolecules can serve as valuable biomarkers for diseases and pathologies. The objectives of this study were to characterize MM at 9.4T in the human brain (occipital and left parietal lobe) and to describe the RF coil setup used for MM acquisition in the two regions. An adiabatic inversion pulse was optimised for metabolite nulling at 9.4T using double inversion recovery and was combined for the first time with metabolite cycled (MC) semi-LASER and appropriate coil configuration. MM spectra (seven volunteers) from two brain locations were averaged and smoothed creating MM templates, which were then parametrized using simulated Voigt-shaped lines within LCModel. Quantification was performed on individual data sets, including corrections for different tissue composition and the T 1 and T 2 relaxation of water. Our coil configuration method resulted in efficient B1+ (>30 T/√kW) for both brain regions. The 15 MM components were detected and quantified in MM baselines of the two brain areas. No significant differences in concentration levels of MM between different regions were found. Two new MM peaks were reported (M7 & M8). Double inversion, which was combined with MC semi-LASER, enabled the acquisition of high spectral resolution MM spectra for both brain regions at 9.4T. The 15 MM components were detected and quantified. Two new MM peaks were reported for the first time (M7 & M8) and preliminarily assigned to β-methylene protons of aspartyl-groups. Magn Reson Med 80:462-473, 2018. © 2018 International Society for Magnetic Resonance in Medicine. © 2018 International Society for Magnetic Resonance in Medicine.

Transfer matrix approach to electron transport in monolayer MoS2/MoO x heterostructures

NASA Astrophysics Data System (ADS)

Li, Gen

2018-05-01

Oxygen plasma treatment can introduce oxidation into monolayer MoS2 to transfer MoS2 into MoO x , causing the formation of MoS2/MoO x heterostructures. We find the MoS2/MoO x heterostructures have the similar geometry compared with GaAs/Ga1‑x Al x As semiconductor superlattice. Thus, We employ the established transfer matrix method to analyse the electron transport in the MoS2/MoO x heterostructures with double-well and step-well geometries. We also considere the coupling between transverse and longitudinal kinetic energy because the electron effective mass changes spatially in the MoS2/MoO x heterostructures. We find the resonant peaks show red shift with the increasing of transverse momentum, which is similar to the previous work studying the transverse-momentum-dependent transmission in GaAs/Ga1‑x Al x As double-barrier structure. We find electric field can enhance the magnitude of peaks and intensify the coupling between longitudinal and transverse momentums. Moreover, higher bias is applied to optimize resonant tunnelling condition to show negative differential effect can be observed in the MoS2/MoO x system.

High temperature sensor properties of a specialty double cladding fiber

NASA Astrophysics Data System (ADS)

Zhou, Ting; Pang, Fufei; Wang, Tingyun

2011-12-01

A simple high temperature fiber sensor is proposed and demonstrated. The sensor head is made of a short section of specialty double cladding fiber (DCF). The DCF consists of a depressed inner cladding which is boron (B)-doped silica. Through an evanescent wave, the cladding mode can be excited, and thus the transmission presents a resonant spectral dip. The high temperature sensing properties was studied according to the shift of the transmission spectrum shifts. With increasing the temperature from 28 °C to 850 °C, the resonant spectrum shifts to longer wavelengths. The sensitivity is 0.112 nm / °C.

Modeling the double charge exchange response function for a tetraneutron system

NASA Astrophysics Data System (ADS)

Lazauskas, R.; Carbonell, J.; Hiyama, E.

2017-07-01

This work is an attempt to model the 4 n response function of a recent RIKEN experimental study of the double charge exchange  4 He( 8 He, 8 Be) 4n reaction in order to put in evidence an eventual enhancement mechanism of the zero-energy cross section, including a near-threshold resonance. This resonance can indeed be reproduced only by adding to the standard nuclear Hamiltonian an unphysically large T =3/2 attractive 3 n -force that destroys the neighboring nuclear chart. No other mechanisms, like cusps or related structures, were found.

Infrared-Terahertz Double-Resonance Spectroscopy of CH3F and CH3Cl at Atmospheric Pressure

DTIC Science & Technology

2012-05-16

coincidence with the RQ3(6) rovibrational transition in CH3 35Cl [Fig. 4(b)]. At atmospheric pressure, nine more P -, Q-, and R-branch rovibrational...the double-resonance signatures of all IR-THz pump-probe coincidences at atmospheric pressure for 12CH3F and CH3 35Cl 052507-11050-2947/2012/85(5...were calculated using the rotational constants listed in Tables I and II. For CH3F, the standard P - type (J = − 1), Q-type (J = 0), and R-type (J

Metallic metasurfaces for high efficient polarization conversion control in transmission mode.

PubMed

Li, Tong; Hu, Xiaobin; Chen, Huamin; Zhao, Chen; Xu, Yun; Wei, Xin; Song, Guofeng

2017-10-02

A high efficient broadband polarization converter is an important component in integrated miniaturized optical systems, but its performances is often restricted by the material structures, metallic metasurfaces for polarization control in transmission mode never achieved efficiency above 0.5. Herein, we theoretically demonstrate that metallic metasurfaces constructed by thick cross-shaped particles can realize a high efficient polarization transformation over a broadband. We investigated the resonant properties of designed matesurfaces and found that the interaction between double FP cavity resonances and double bulk magnetic resonances is the main reason to generate a high transmissivity over a broadband. In addition, through using four resonances effect and tuning the anisotropic optical response, we realized a high efficient (> 0.85) quarter-wave plate at the wavelength range from 1175nm to 1310nm and a high efficient (> 0.9) half-wave plate at the wavelength range from 1130nm to 1230nm. The proposed polarization converters may have many potential applications in integrated polarization conversion devices and optical data storage systems.

High sensitivity rotation sensing based on tunable asymmetrical double-ring structure

NASA Astrophysics Data System (ADS)

Gu, Hong; Liu, Xiaoqing

2017-05-01

A very high sensitivity rotation sensor comprising a tunable asymmetrical double-ring structure (TADRS) coupled by a 3 × 3 coupler is presented. The phase difference caused by the TADRS between the counter-propagating waves is derived and discussed. At the resonant frequency, the phase shift difference has the maximum value when the light power in one cavity is amplified about 1.85 times while attenuated 79% in another. The maximum sensitivity of the TADRS sensor is two times larger than that of a single-ring structure. An experimental system is designed to verify the theoretical results and introduce the method of demodulation. The rotation sensor based on TADRS can enhance the sensitivity of the detection of the angular velocity by more than three orders of magnitude.

Time-domain simulation of nonlinear radiofrequency phenomena

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jenkins, Thomas G.; Austin, Travis M.; Smithe, David N.

Nonlinear effects associated with the physics of radiofrequency wave propagation through a plasma are investigated numerically in the time domain, using both fluid and particle-in-cell (PIC) methods. We find favorable comparisons between parametric decay instability scenarios observed on the Alcator C-MOD experiment [J. C. Rost, M. Porkolab, and R. L. Boivin, Phys. Plasmas 9, 1262 (2002)] and PIC models. The capability of fluid models to capture important nonlinear effects characteristic of wave-plasma interaction (frequency doubling, cyclotron resonant absorption) is also demonstrated.

Time-domain simulation of nonlinear radiofrequency phenomena

NASA Astrophysics Data System (ADS)

Jenkins, Thomas G.; Austin, Travis M.; Smithe, David N.; Loverich, John; Hakim, Ammar H.

2013-01-01

Nonlinear effects associated with the physics of radiofrequency wave propagation through a plasma are investigated numerically in the time domain, using both fluid and particle-in-cell (PIC) methods. We find favorable comparisons between parametric decay instability scenarios observed on the Alcator C-MOD experiment [J. C. Rost, M. Porkolab, and R. L. Boivin, Phys. Plasmas 9, 1262 (2002)] and PIC models. The capability of fluid models to capture important nonlinear effects characteristic of wave-plasma interaction (frequency doubling, cyclotron resonant absorption) is also demonstrated.

Active control of sound transmission through a double panel partition

NASA Astrophysics Data System (ADS)

Sas, P.; Bao, C.; Augusztinovicz, F.; Desmet, W.

1995-03-01

The feasibility of improving the insertion loss of lightweight double panel partitions by using small loudspeakers as active noise control sources inside the air gap between both panels of the partition is investigated analytically, numerically and experimentally in this paper. A theoretical analysis of the mechanisms of the fluid-structure interaction of double panel structures is presented in order to gain insight into the physical phenomena underlying the behaviour of a coupled vibro-acoustic system controlled by active methods. The analysis, based on modal coupling theory, enables one to derive some qualitative predictions concerning the potentials and limitations of the proposed approach. The theoretical analysis is valid only for geometrically simple structures. For more complex geometries, numerical simulations are required. Therefore the potential use of active noise control inside double panel structures has been analyzed by using coupled finite element and boundary element methods. To verify the conclusions drawn from the theoretical analysis and the numerical calculation and, above all, to demonstrate the potential of the proposed approach, experiments have been conducted with a laboratory set-up. The performance of the proposed approach was evaluated in terms of relative insertion loss measurements. It is shown that a considerable improvement of the insertion loss has been achieved around the lightly damped resonances of the system for the frequency range investigated (60-220 Hz).

The double-opposing buccal flap procedure for palatal lengthening.

PubMed

Mann, Robert J; Neaman, Keith C; Armstrong, Shannon D; Ebner, Ben; Bajnrauh, Robert; Naum, Steven

2011-06-01

Velopharyngeal dysfunction has been treated with either a pharyngeal flap or sphincteroplasty with varying degrees of success. Both of these entities have their own series of problems, with sleep apnea and nasal mucous flow disruptions at the forefront. The purpose of this study was to review the senior author's (R.J.M.) experience performing the double-opposing buccal flap for palatal lengthening. All patients who were treated with double-opposing buccal flaps between October of 1994 and July of 2007 were reviewed. These patients presented with varying degrees of velopharyngeal dysfunction showing some degree of velar movement at the time of surgery. Preoperative and postoperative speech results were reviewed for comparison. Twenty-seven patients underwent palatal lengthening, with an average length of follow-up of 58 months. Distal flap necrosis occurred in two patients. The level of intelligibility (65.4 percent versus 95.5 percent) and resonance (moderately hypernasal versus normal resonance) improved significantly postoperatively (p < 0.0001). Only one patient required the addition of a pharyngeal flap for persistent velopharyngeal dysfunction, and there were no postoperative issues with sleep apnea. The double-opposing buccal flap is an effective technique for lengthening the palate, improving speech, and decreasing the risks of postoperative sleep apnea. All patients experienced a dramatic improvement in their resonance and intelligibility. This technique appears most effective in patients with intact velar movement who demonstrate a small to moderate posterior velar gap. The double-opposing buccal flap is a useful means of treating velopharyngeal dysfunction, thus serving as an adjunct when improving pharyngeal closure.

Quantum scattering in one-dimensional systems satisfying the minimal length uncertainty relation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernardo, Reginald Christian S., E-mail: rcbernardo@nip.upd.edu.ph; Esguerra, Jose Perico H., E-mail: jesguerra@nip.upd.edu.ph

In quantum gravity theories, when the scattering energy is comparable to the Planck energy the Heisenberg uncertainty principle breaks down and is replaced by the minimal length uncertainty relation. In this paper, the consequences of the minimal length uncertainty relation on one-dimensional quantum scattering are studied using an approach involving a recently proposed second-order differential equation. An exact analytical expression for the tunneling probability through a locally-periodic rectangular potential barrier system is obtained. Results show that the existence of a non-zero minimal length uncertainty tends to shift the resonant tunneling energies to the positive direction. Scattering through a locally-periodic potentialmore » composed of double-rectangular potential barriers shows that the first band of resonant tunneling energies widens for minimal length cases when the double-rectangular potential barrier is symmetric but narrows down when the double-rectangular potential barrier is asymmetric. A numerical solution which exploits the use of Wronskians is used to calculate the transmission probabilities through the Pöschl–Teller well, Gaussian barrier, and double-Gaussian barrier. Results show that the probability of passage through the Pöschl–Teller well and Gaussian barrier is smaller in the minimal length cases compared to the non-minimal length case. For the double-Gaussian barrier, the probability of passage for energies that are more positive than the resonant tunneling energy is larger in the minimal length cases compared to the non-minimal length case. The approach is exact and applicable to many types of scattering potential.« less

CP violation induced by the double resonance for pure annihilation decay process in perturbative QCD

DOE PAGES

Lü, Gang; Lu, Ye; Li, Sheng-Tao; ...

2017-08-04

In a perturbative QCD approach we study the direct CP violation in the pure annihilation decay process ofmore » $$\\bar{B}$$$0\\atop{s}$$→π +π -π +π - induced by the ρ and ω double resonance effect.Generally, the CP violation is small in the pure annihilation type decay process. But, we find that the CP violation can be enhanced by doubleinterference when the invariant masses of the π + π - pairs are in the vicinity of the ω resonance. For the decay process of $$\\bar{B}$$$0\\atop{s}$$→π +π -π +π -, the CP violation can reach ACP($$\\bar{B}$$$0\\atop{s}$$→π +π -π +π -)=27.20$$+0.05+0.28+7.13\\atop{-0.15-0.31-6.11}$$%.« less

CP violation induced by the double resonance for pure annihilation decay process in perturbative QCD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lü, Gang; Lu, Ye; Li, Sheng-Tao

In a perturbative QCD approach we study the direct CP violation in the pure annihilation decay process ofmore » $$\\bar{B}$$$0\\atop{s}$$→π +π -π +π - induced by the ρ and ω double resonance effect.Generally, the CP violation is small in the pure annihilation type decay process. But, we find that the CP violation can be enhanced by doubleinterference when the invariant masses of the π + π - pairs are in the vicinity of the ω resonance. For the decay process of $$\\bar{B}$$$0\\atop{s}$$→π +π -π +π -, the CP violation can reach ACP($$\\bar{B}$$$0\\atop{s}$$→π +π -π +π -)=27.20$$+0.05+0.28+7.13\\atop{-0.15-0.31-6.11}$$%.« less

Compact all-fiber figure-9 dissipative soliton resonance mode-locked double-clad Er:Yb laser.

PubMed

Krzempek, Karol; Sotor, Jaroslaw; Abramski, Krzysztof

2016-11-01

The first demonstration of a compact all-fiber figure-9 double-clad erbium-ytterbium laser working in the dissipative soliton resonance (DSR) regime is presented. Mode-locking was achieved using a nonlinear amplifying loop (NALM) resonator configuration. The laser was assembled with an additional 475 m long spool of SMF28 fiber in the NALM loop in order to obtain large net-anomalous cavity dispersion (-10.4  ps²), and therefore ensure that DSR would be the dominant mode-locking mechanism. At maximum pump power (4.78 W) the laser generated rectangular-shaped pulses with 455 ns duration and an average power of 950 mW, which at a repetition frequency of 412 kHz corresponds to a record energy of 2.3 μJ per pulse.

Sequential double photodetachment of He- in elliptically polarized laser fields

NASA Astrophysics Data System (ADS)

Génévriez, Matthieu; Dunseath, Kevin M.; Terao-Dunseath, Mariko; Urbain, Xavier

2018-02-01

Four-photon double detachment of the helium negative ion is investigated experimentally and theoretically for photon energies where the transient helium atom is in the 1 s 2 s 3S or 1 s 2 p P3o states, which subsequently ionize by absorption of three photons. Ionization is enhanced by intermediate resonances, giving rise to series of peaks in the He+ spectrum, which we study in detail. The He+ yield is measured in the wavelength ranges from 530 to 560 nm and from 685 to 730 nm and for various polarizations of the laser light. Double detachment is treated theoretically as a sequential process, within the framework of R -matrix theory for the first step and effective Hamiltonian theory for the second step. Experimental conditions are accurately modeled, and the measured and simulated yields are in good qualitative and, in some cases, quantitative agreement. Resonances in the double detachment spectra can be attributed to well-defined Rydberg states of the transient atom. The double detachment yield exhibits a strong dependence on the laser polarization which can be related to the magnetic quantum number of the intermediate atomic state. We also investigate the possibility of nonsequential double detachment with a two-color experiment but observe no evidence for it.

Deformation-induced splitting of the isoscalar E 0 giant resonance: Skyrme random-phase-approximation analysis

NASA Astrophysics Data System (ADS)

Kvasil, J.; Nesterenko, V. O.; Repko, A.; Kleinig, W.; Reinhard, P.-G.

2016-12-01

The deformation-induced splitting of isoscalar giant monopole resonance (ISGMR) is systematically analyzed in a wide range of masses covering medium, rare-earth, actinide, and superheavy axial deformed nuclei. The study is performed within the fully self-consistent quasiparticle random-phase-approximation method based on the Skyrme functional. Two Skyrme forces, one with a large (SV-bas) and one with a small (SkP) nuclear incompressibility, are considered. The calculations confirm earlier results that, because of the deformation-induced E 0 -E 2 coupling, the isoscalar E 0 resonance attains a double-peak structure and significant energy upshift. Our results are compared with available analytic estimations. Unlike earlier studies, we get a smaller energy difference between the lower and upper peaks and thus a stronger E 0 -E 2 coupling. This in turn results in more pumping of E 0 strength into the lower peak and more pronounced splitting of ISGMR. We also discuss widths of the peaks and their negligible correlation with deformation.

Vertical resonant tunneling transistors with molecular quantum dots for large-scale integration.

PubMed

Hayakawa, Ryoma; Chikyow, Toyohiro; Wakayama, Yutaka

2017-08-10

Quantum molecular devices have a potential for the construction of new data processing architectures that cannot be achieved using current complementary metal-oxide-semiconductor (CMOS) technology. The relevant basic quantum transport properties have been examined by specific methods such as scanning probe and break-junction techniques. However, these methodologies are not compatible with current CMOS applications, and the development of practical molecular devices remains a persistent challenge. Here, we demonstrate a new vertical resonant tunneling transistor for large-scale integration. The transistor channel is comprised of a MOS structure with C 60 molecules as quantum dots, and the structure behaves like a double tunnel junction. Notably, the transistors enabled the observation of stepwise drain currents, which originated from resonant tunneling via the discrete molecular orbitals. Applying side-gate voltages produced depletion layers in Si substrates, to achieve effective modulation of the drain currents and obvious peak shifts in the differential conductance curves. Our device configuration thus provides a promising means of integrating molecular functions into future CMOS applications.

Helium isotope enrichment by resonant tunneling through nanoporous graphene bilayers.

PubMed

Mandrà, Salvatore; Schrier, Joshua; Ceotto, Michele

2014-08-21

Graphene is impermeable to gases, but introducing subnanometer pores can allow for selective gas separation. Because graphene is only one atom thick, tunneling can play an important role, especially for low-mass gases such as helium, and this has been proposed as a means of separating (3)He from (4)He. In this paper, we consider the possibility of utilizing resonant tunneling of helium isotopes through nanoporous graphene bilayers. Using a model potential fit to previously reported DFT potential energy surfaces, we calculate the thermal rate constant as a function of interlayer separation using a recently described time-independent method for arbitrary multibarrier potentials. Resonant transmission allows for the total flux rate of (3)He to remain the same as the best-known single-barrier pores but doubles the selectivity with respect to (4)He when the optimal interlayer spacing of 4.6 Å is used. The high flux rate and selectivity are robust against variations of the interlayer spacing and asymmetries in the potential that may occur in experiment.

Benchmark Testing of a New 56Fe Evaluation for Criticality Safety Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leal, Luiz C; Ivanov, E.

2015-01-01

The SAMMY code was used to evaluate resonance parameters of the 56Fe cross section in the resolved resonance energy range of 0–2 MeV using transmission data, capture, elastic, inelastic, and double differential elastic cross sections. The resonance analysis was performed with the code SAMMY that fits R-matrix resonance parameters using the generalized least-squares technique (Bayes’ theory). The evaluation yielded a set of resonance parameters that reproduced the experimental data very well, along with a resonance parameter covariance matrix for data uncertainty calculations. Benchmark tests were conducted to assess the evaluation performance in benchmark calculations.

Simultaneous excitation of extremely high-Q-factor trapped and octupolar modes in terahertz metamaterials.

PubMed

Yang, Shengyan; Tang, Chengchun; Liu, Zhe; Wang, Bo; Wang, Chun; Li, Junjie; Wang, Li; Gu, Changzhi

2017-07-10

Achieving high-Q-factor resonances allows dramatic enhancement of performance of many plasmonic devices. However, the excitation of high-Q-factor resonance, especially multiple high-Q-factor resonances, has been a big challenge in traditional metamaterials due to the ohmic and radiation losses. Here, we experimentally demonstrate simultaneous excitation of double extremely sharp resonances in a terahertz metamaterial composed of mirror-symmetric-broken double split ring resonators (MBDSRRs). In a regular mirror-arranged SRR array, only the low-Q-factor dipole resonance can be excited with the external electric field perpendicular to the SRR gap. Breaking the mirror-symmetry of the metamaterial leads to the occurrence of two distinct otherwise inaccessible ultrahigh-Q-factor modes, which consists of one trapped mode in addition to an octupolar mode. By tuning the asymmetry parameter, the Q factor of the trapped mode can be linearly modulated, while the Q factor of the octupolar mode can be tailored exponentially. For specific degree of asymmetry, our simulations revealed a significantly high Q factor (Q>100) for the octupolar mode, which is more than one order of magnitude larger than that of conventional metamaterials. The mirror-symmetry-broken metamaterial offers the advantage of enabling access to two distinct high-Q-factor resonances which could be exploited for ultrasensitive sensors, multiband filters, and slow light devices.

Gold Nanoparticle-Aptamer-Based LSPR Sensing of Ochratoxin A at a Widened Detection Range by Double Calibration Curve Method

NASA Astrophysics Data System (ADS)

Liu, Boshi; Huang, Renliang; Yu, Yanjun; Su, Rongxin; Qi, Wei; He, Zhimin

2018-04-01

Ochratoxin A (OTA) is a type of mycotoxin generated from the metabolism of Aspergillus and Penicillium, and is extremely toxic to humans, livestock, and poultry. However, traditional assays for the detection of OTA are expensive and complicated. Other than OTA aptamer, OTA itself at high concentration can also adsorb on the surface of gold nanoparticles (AuNPs), and further inhibit AuNPs salt aggregation. We herein report a new OTA assay by applying the localized surface plasmon resonance effect of AuNPs and their aggregates. The result obtained from only one single linear calibration curve is not reliable, and so we developed a “double calibration curve” method to address this issue and widen the OTA detection range. A number of other analytes were also examined, and the structural properties of analytes that bind with the AuNPs were further discussed. We found that various considerations must be taken into account in the detection of these analytes when applying AuNP aggregation-based methods due to their different binding strengths.

Fabrication and analysis of radiofrequency MEMS series capacitive single-pole double-throw switch

NASA Astrophysics Data System (ADS)

Bansal, Deepak; Bajpai, Anuroop; Kumar, Prem; Kaur, Maninder; Rangra, Kamaljit

2016-10-01

A compact radiofrequency (RF) MEMS single-pole double-throw (SPDT) switch based on series capacitive configuration is proposed. The critical process parameters are analyzed to improve the fabrication process. A technique of cold-hot thermal shock for lift-off method is explored. The residual stress in the structure is quantified by lancet test structures that come out to be 51 MPa. Effect of residual stress on actuation voltage is explored, which changes its value from 24 to 22 V. Resonance frequency and switching speed of the switch are 11 kHz and 44 μs, respectively, measured using laser Doppler vibrometer. Measured bandwidth of the SPDT switch is 20 GHz (5 to 25 GHz), which is verified with finite element method simulations in high frequency structure simulator©; and an equivalent LCR circuit in advanced design system©;. Insertion loss of the switch lies in -0.1 to -0.5 dB with isolation better than -20 dB for the above-mentioned bandwidth.

Phase Acrobatics: The Influence of Excitonic Resonance and Gold Nonresonant Background on Heterodyne-Detected Vibrational Sum Frequency Generation Emission.

PubMed

Rich, Christopher C; Lindberg, Kathryn A; Krummel, Amber T

2017-04-06

We show how heterodyne-detected vibrational sum frequency generation (HD-VSFG) spectroscopy can discriminate between the excitonic and monomeric properties of a helical, nanotube molecular aggregate by monitoring the phase of the VSFG emission associated with different polarization configurations. By keeping track of the "phase acrobatics" associated with the added phase of the nonresonant SFG emission of gold as well as that of the double-resonance conditions achieved when the SF frequency is resonant with an electronic exciton transition, we discover that for aggregates of tetra(sulfonatophenyl)porphyrin (TSPP) the PPP-polarized spectra exhibit double-resonance conditions while SSP-polarized spectra exhibit resonance only with the ground-state vibration. Along with observed shifts in the vibrational frequency, intensity differences, and sign flips in the imaginary second-order susceptibility, χ s,Im (2) , we conclude that PPP-polarized HD-VSFG spectra reflect the delocalized, excitonic nature of the molecular aggregate, while the SSP-polarized HD-VSFG spectra measure the localized, monomeric nature of the molecular subunits. It is implied from this study that HD-VSFG spectroscopy can be uniquely utilized to measure the excitonic and monomeric properties associated with molecular assemblies for a single sample.

Sensitive enhancement of vessel wall imaging with an endoesophageal Wireless Amplified NMR Detector (WAND).

PubMed

Zeng, Xianchun; Barbic, Mladen; Chen, Liangliang; Qian, Chunqi

2017-11-01

To improve the imaging quality of vessel walls with an endoesophageal Wireless Amplified NMR Detector (WAND). A cylindrically shaped double-frequency resonator has been constructed with a single metal wire that is self-connected by a pair of nonlinear capacitors. The double-frequency resonator can convert wirelessly provided pumping power into amplified MR signals. This compact design makes the detector easily insertable into a rodent esophagus. The detector has good longitudinal and axial symmetry. Compared to an external surface coil, the WAND can enhance detection sensitivity by at least 5 times, even when the distance separation between the region of interest and the detector's cylindrical surface is twice the detector's own radius. Such detection capability enables us to observe vessel walls near the aortic arch and carotid bifurcation with elevated sensitivity. A cylindrical MRI detector integrated with a wireless-powered amplifier has been developed as an endoesophageal detector to enhance detection sensitivity of vessel walls. This detector can greatly improve the imaging quality for vessel regions that are susceptible to atherosclerotic lesions. Magn Reson Med 78:2048-2054, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Nonlinear Modeling of Radial Stellar Pulsations

NASA Astrophysics Data System (ADS)

Smolec, R.

2009-09-01

In this thesis, I present the results of my work concerning the nonlinear modeling of radial stellar pulsations. I will focus on classical Cepheids, particularly on the double-mode phenomenon. History of nonlinear modeling of radial stellar pulsations begins in the sixties of the previous century. At the beginning convection was disregarded in model equations. Qualitatively, almost all features of the radial pulsators were successfully modeled with purely radiative hydrocodes. Among problems that remained, the most disturbing was modeling of the double-mode phenomenon. This long-standing problem seemed to be finally solved with the inclusion of turbulent convection into the model equations (Kollath et al. 1998, Feuchtinger 1998). Although dynamical aspects of the double-mode behaviour were extensively studied, its origin, particularly the specific role played by convection, remained obscure. To study this and other problems of radial stellar pulsations, I implemented the convection into pulsation hydrocodes. The codes adopt the Kuhfuss (1986) convection model. In other codes, particularly in the Florida-Budapest hydrocode (e.g. Kollath et al. 2002), used in comput! ation of most of the published double-mode models, different approximations concerning e.g. eddy-viscous terms or treatment of convectively stable regions are adopted. Particularly the neglect of negative buoyancy effects in the Florida-Budapest code and its consequences, were never discussed in the literature. These consequences are severe. Concerning the single-mode pulsators, neglect of negative buoyancy leads to smaller pulsation amplitudes, in comparison to amplitudes computed with code including these effects. Particularly, neglect of negative buoyancy reduces the amplitude of the fundamental mode very strong. This property of the Florida-Budapest models is crucial in bringing up the stable non-resonant double-mode Cepheid pulsation involving fundamental and first overtone modes (F/1O). Such pulsation is not observed in models computed including negative buoyancy. As the neglect of negative buoyancy is physically not correct, so are the double-mode Cepheid models computed with the Florida-Budapest hydrocode. Extensive search for F/1O double-mode Cepheid pulsation with the codes including negative buoyancy effects yielded null result. Some resonant double-mode F/1O Cepheid models were found, but their occurrence was restricted to a very narrow domain in the Hertzsprung-Russel diagram. Model computations intended to model the double-overtone (1O/2O) Cepheids in the Large Magellanic Cloud, also revealed some stable double-mode pulsations, however, restricted to a narrow period range. Resonances are most likely conductive in bringing up the double-mode behaviour observed in these models. However, majority of the double-overtone LMC Cepheids cannot be reproduced with our codes. Hence, the modeling of double-overtone Cepheids with convective hydrocodes is not satisfactory, either. Double-mode pulsation still lacks satisfactory explanation, and problem of its modeling remains open.

Theoretical nuclear physics

NASA Astrophysics Data System (ADS)

Rost, E.; Shephard, J. R.

1992-08-01

This report discusses the following topics: Exact 1-loop vacuum polarization effects in 1 + 1 dimensional QHD; exact 1-fermion loop contributions in 1 + 1 dimensional solitons; exact scalar 1-loop contributions in 1 + 3 dimensions; exact vacuum calculations in a hyper-spherical basis; relativistic nuclear matter with self-consistent correlation energy; consistent RHA-RPA for finite nuclei; transverse response functions in the (triangle)-resonance region; hadronic matter in a nontopological soliton model; scalar and vector contributions to (bar p)p yields (bar lambda)lambda reaction; 0+ and 2+ strengths in pion double-charge exchange to double giant-dipole resonances; and nucleons in a hybrid sigma model including a quantized pion field.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jenkovszky, L. L., E-mail: jenk@bitp.kiev.ua; Kuprash, O. E., E-mail: oleg.kuprash@desy.de; Orava, R., E-mail: risto.orava@cern.ch

The cross sections for single and double diffraction dissociation at low missing masses are calculated for the LHC energies on the basis of the dual (Regge) model under the assumption of a dominant contribution of the exchange of the Pomeron Regge pole. The model reproduces the rich resonance structure in the region of low missing masses M{sub x}. Diffractively excited states lie on the nucleon trajectory M{sub x} supplemented with the isolated Roper resonance. Detailed predictions for the squared momentum transfer and missing-mass dependence of the differential and integrated single and double diffraction dissociation in the kinematical range of presentmore » and future LHC measurements are given.« less

Bandwidth-induced reversal of asymmetry in optical-double-resonance amplitudes

NASA Astrophysics Data System (ADS)

Nitz, D. E.; Smith, A. V.; Levenson, M. D.; Smith, S. J.

1981-07-01

Optical-double-resonance measurements using ionization detection have been carried out in the 3S12-3P12-4D atomic-sodium system. Asymmetries observed in production of 4D atoms from the two components of the Stark-split 3P12 state are found to be controlled by the far, very weak wings of the 17-MHz full-width-at-half-maximum laser line which is used to drive the 3S12-3P12 transition at detunings in the range 0-70 GHz. Suppression of the wings with a Fabry-Perot filter causes a pronounced reversal of the asymmetry.

Barium Tagging from nEXO Using Resonance Ionization Spectroscopy

NASA Astrophysics Data System (ADS)

Twelker, K.; Kravitz, S.

nEXO is a 5-ton liquid enriched-xenon time projection chamber (TPC) to search for neutrinoless double-beta decay, designed to have the sensitivity to completely probe the inverted mass hierarchy of Majorana neutrinos. The detector will accommodate-as a background reduction technique-a system to recover and identify the barium decay product. This upgrade will allow a background-free measurement of neutrinoless double-beta decay and increase the half-life sensitivity of the experiment by at least one order of magnitude. Ongoing research and development includes a system to test barium extraction from liquid xenon using surface adsorption and Resonance Ionization Spectroscopy (RIS).

Triad Resonance in the Gravity-Acoustic Family

NASA Astrophysics Data System (ADS)

Kadri, U.

2015-12-01

Resonance interactions of waves play a prominent role in energy share among the different wave types involved. Such interactions may significantly contribute, among others, to the evolution of the ocean energy spectrum by exchanging energy between surface-gravity waves; surface and internal gravity waves; or even surface and compression-type waves, that can transfer energy from the upper ocean through the whole water column reaching down to the seafloor. A resonant triad occurs among a triplet of waves, usually involving interaction of nonlinear terms of second order perturbed equations. Until recently, it has been believed that in a homogeneous fluid a resonant triad is possible only when tension forces are included, or at the limit of a shallow water, and that when the compressibility of water is considered, no resonant triads can occur within the family of gravity-acoustic waves. However, more recently it has been proved that, under some circumstances, resonant triads comprising two opposing surface-gravity waves of similar periods (though not identical) and a much longer acoustic-gravity wave, of almost double the frequency, exist [Kadri and Stiassnie 2013, J. Fluid Mech.735 R6]. Here, I report on a new resonant triad involving a gravity wave and two acoustic waves of almost double the length. Interestingly, the two acoustic waves propagate in the same direction with similar wavelengths, that are almost double of that of the gravity wave. The evolution of the wave triad amplitudes is periodic and it is derived analytically, in terms of Jacobian elliptic functions and elliptic integrals. The physical importance of this type of triad interactions is the modulation of pertinent acoustic signals, leading to inaccurate signal perceptions. Enclosed figure: presents an example spatio-temporal evolution of the wave triad amplitudes. The gravity wave (top) remains almost unaltered, while the envelope slowly displaces to the left. However, the prescribed acoustic envelope (middle) travels relatively fast to the right minimising the interaction time. Consequently, the resultant acoustic wave envelope (bottom) might be significantly smaller. As the two acoustic beams concurrently move away from the gravity wave, with disparate group velocities, the resonant interaction gradually vanishes.

Blue diode-pumped solid-state-laser based on ytterbium doped laser crystals operating on the resonance zero-phonon transition

DOEpatents

Krupke, William F.; Payne, Stephen A.; Marshall, Christopher D.

2001-01-01

The invention provides an efficient, compact means of generating blue laser light at a wavelength near .about.493+/-3 nm, based on the use of a laser diode-pumped Yb-doped laser crystal emitting on its zero phonon line (ZPL) resonance transition at a wavelength near .about.986+/-6 nm, whose fundamental infrared output radiation is harmonically doubled into the blue spectral region. The invention is applied to the excitation of biofluorescent dyes (in the .about.490-496 nm spectral region) utilized in flow cytometry, immunoassay, DNA sequencing, and other biofluorescence instruments. The preferred host crystals have strong ZPL fluorecence (laser) transitions lying in the spectral range from .about.980 to .about.992 nm (so that when frequency-doubled, they produce output radiation in the spectral range from 490 to 496 nm). Alternate preferred Yb doped tungstate crystals, such as Yb:KY(WO.sub.4).sub.2, may be configured to lase on the resonant ZPL transition near 981 nm (in lieu of the normal 1025 nm transition). The laser light is then doubled in the blue at 490.5 nm.

Vertical transport in graphene-hexagonal boron nitride heterostructure devices

PubMed Central

Bruzzone, Samantha; Logoteta, Demetrio; Fiori, Gianluca; Iannaccone, Giuseppe

2015-01-01

Research in graphene-based electronics is recently focusing on devices based on vertical heterostructures of two-dimensional materials. Here we use density functional theory and multiscale simulations to investigate the tunneling properties of single- and double-barrier structures with graphene and few-layer hexagonal boron nitride (h-BN) or hexagonal boron carbon nitride (h-BC2N). We find that tunneling through a single barrier exhibit a weak dependence on energy. We also show that in double barriers separated by a graphene layer we do not observe resonant tunneling, but a significant increase of the tunneling probability with respect to a single barrier of thickness equal to the sum of the two barriers. This is due to the fact that the graphene layer acts as an effective phase randomizer, suppressing resonant tunneling and effectively letting a double-barrier structure behave as two single-barriers in series. Finally, we use multiscale simulations to reproduce a current-voltage characteristics resembling that of a resonant tunneling diode, that has been experimentally observed in single barrier structure. The peak current is obtained when there is perfect matching between the densities of states of the cathode and anode graphene regions. PMID:26415656

Valley-spin filtering through a nonmagnetic resonant tunneling structure in silicene

NASA Astrophysics Data System (ADS)

Wu, Xiuqiang; Meng, Hao; Zhang, Haiyang; Bai, Yujie; Xu, Xing

2018-07-01

We theoretically investigate how a silecene-based nonmagnetic resonant-tunneling structure, i.e. a double electrostatic potential structure, can be tailored to generate valley- and spin-polarized filtering by using the scattering matrix method. This method allows us to find simple analytical expressions for the scattering amplitudes. It is found that the transmissions of electrons from opposite spin and valley show exactly opposite behaviors, leading to valley and spin filtering in a wide range of transmission directions. These directional-dependent valley-spin polarization behaviors can be used to select preferential directions along which the valley-spin polarization of an initially unpolarized carrier can be strongly enhanced. We also find that this phenomenon arises from the combinations of the coherent effect, electrostatic potential and external electric field. Especially when the direction of the external electric field is changed, the spin filtering properties are contained, while the valley filtering properties can be switched. In addition, the filtering behaviors can be conveniently controlled by electrical gating. Therefore, the results can offer an all-electric method to construct a valley-spin filter in silicene.

Resonant responses and chaotic dynamics of composite laminated circular cylindrical shell with membranes

NASA Astrophysics Data System (ADS)

Zhang, W.; Liu, T.; Xi, A.; Wang, Y. N.

2018-06-01

This paper is focused on the resonant responses and chaotic dynamics of a composite laminated circular cylindrical shell with radially pre-stretched membranes at both ends and clamped along a generatrix. Based on the two-degree-of-freedom non-autonomous nonlinear equations of this system, the method of multiple scales is employed to obtain the four-dimensional nonlinear averaged equation. The resonant case considered here is the primary parametric resonance-1/2 subharmonic resonance and 1:1 internal resonance. Corresponding to several selected parameters, the frequency-response curves are obtained. From the numerical results, we find that the hardening-spring-type behaviors and jump phenomena are exhibited. The jump phenomena also occur in the amplitude curves of the temperature parameter excitation. Moreover, it is found that the temperature parameter excitation, the coupling degree of two order modes and the detuning parameters can effect the nonlinear oscillations of this system. The periodic and chaotic motions of the composite laminated circular cylindrical shell clamped along a generatrix are demonstrated by the bifurcation diagrams, the maximum Lyapunov exponents, the phase portraits, the waveforms, the power spectrums and the Poincaré map. The temperature parameter excitation shows that the Pomeau-Manneville type intermittent chaos occur under the certain initial conditions. It is also found that there exist the twin phenomena between the Pomeau-Manneville type intermittent chaos and the period-doubling bifurcation.

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

PubMed

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

2016-04-01

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

Structure and nature of manganese(II) imidazole complexes in frozen aqueous solutions.

PubMed

Un, Sun

2013-04-01

A common feature of a large majority of the manganese metalloenzymes, as well as many synthetic biomimetic complexes, is the bonding between the manganese ion and imidazoles. This interaction was studied by examining the nature and structure of manganese(II) imidazole complexes in frozen aqueous solutions using 285 GHz high magnet-field continuous-wave electron paramagnetic resonance (cw-HFEPR) and 95 GHz pulsed electron-nuclear double resonance (ENDOR) and pulsed electron-double resonance detected nuclear magnetic resonance (PELDOR-NMR). The (55)Mn hyperfine coupling and isotropic g values of Mn(II) in frozen imidazole solutions continuously decreased with increasing imidazole concentration. ENDOR and PELDOR-NMR measurements demonstrated that the structural basis for this behavior arose from the imidazole concentration-dependent distribution of three six-coordinate and two four-coordinate species: [Mn(H2O)6](2+), [Mn(imidazole)(H2O)5](2+), [Mn(imidazole)2(H2O)4](2+), [Mn(imidazole)3(H2O)](2+), and [Mn(imidazole)4](2+). The hyperfine and g values of manganese proteins were also fully consistent with this imidazole effect. Density functional theory methods were used to calculate the structures, spin and charge densities, and hyperfine couplings of a number of different manganese imidazole complexes. The use of density functional theory with large exact-exchange admixture calculations gave isotropic (55)Mn hyperfine couplings that were semiquantitative and of predictive value. The results show that the covalency of the Mn-N bonds play an important role in determining not only magnetic spin parameters but also the structure of the metal binding site. The relationship between the isotropic (55)Mn hyperfine value and the number of imidazole ligands provides a quick and easy test for determining whether a protein binds an Mn(II) ion using histidine residues and, if so, how many are involved. Application of this method shows that as much as 40% of the Mn(II) ions in Deinococcus radiodurans are ligated to two histidines (Tabares, L. C.; Un, S. J. Biol. Chem 2013, in press).

Spectral relationships between kicked Harper and on-resonance double kicked rotor operators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lawton, Wayne; Mouritzen, Anders S.; Wang Jiao

2009-03-15

Kicked Harper operators and on-resonance double kicked rotor operators model quantum systems whose semiclassical limits exhibit chaotic dynamics. Recent computational studies indicate a striking resemblance between the spectra of these operators. In this paper we apply C*-algebra methods to explain this resemblance. We show that each pair of corresponding operators belongs to a common rotation C*-algebra B{sub {alpha}}, prove that their spectra are equal if {alpha} is irrational, and prove that the Hausdorff distance between their spectra converges to zero as q increases if {alpha}=p/q with p and q coprime integers. Moreover, we show that corresponding operators in B{sub {alpha}}more » are homomorphic images of mother operators in the universal rotation C*-algebra A{sub {alpha}} that are unitarily equivalent and hence have identical spectra. These results extend analogous results for almost Mathieu operators. We also utilize the C*-algebraic framework to develop efficient algorithms to compute the spectra of these mother operators for rational {alpha} and present preliminary numerical results that support the conjecture that their spectra are Cantor sets if {alpha} is irrational. This conjecture for almost Mathieu operators, called the ten Martini problem, was recently proven after intensive efforts over several decades. This proof for the almost Mathieu operators utilized transfer matrix methods, which do not exist for the kicked operators. We outline a strategy, based on a special property of loop groups of semisimple Lie groups, to prove this conjecture for the kicked operators.« less

Quantification of wall shear stress in large blood vessels using Lagrangian interpolation functions with cine phase-contrast magnetic resonance imaging.

PubMed

Cheng, Christopher P; Parker, David; Taylor, Charles A

2002-09-01

Arterial wall shear stress is hypothesized to be an important factor in the localization of atherosclerosis. Current methods to compute wall shear stress from magnetic resonance imaging (MRI) data do not account for flow profiles characteristic of pulsatile flow in noncircular vessel lumens. We describe a method to quantify wall shear stress in large blood vessels by differentiating velocity interpolation functions defined using cine phase-contrast MRI data on a band of elements in the neighborhood of the vessel wall. Validation was performed with software phantoms and an in vitro flow phantom. At an image resolution corresponding to in vivo imaging data of the human abdominal aorta, time-averaged, spatially averaged wall shear stress for steady and pulsatile flow were determined to be within 16% and 23% of the analytic solution, respectively. These errors were reduced to 5% and 8% with doubling in image resolution. For the pulsatile software phantom, the oscillation in shear stress was predicted to within 5%. The mean absolute error of circumferentially resolved shear stress for the nonaxisymmetric phantom decreased from 28% to 15% with a doubling in image resolution. The irregularly shaped phantom and in vitro investigation demonstrated convergence of the calculated values with increased image resolution. We quantified the shear stress at the supraceliac and infrarenal regions of a human abdominal aorta to be 3.4 and 2.3 dyn/cm2, respectively.

I-V characteristics of graphene nanoribbon/h-BN heterojunctions and resonant tunneling.

PubMed

Wakai, Taiga; Sakamoto, Shoichi; Tomiya, Mitsuyoshi

2018-07-04

We present the first principle calculations of the electrical properties of graphene sheet/h-BN heterojunction (GS/h-BN) and 11-armchair graphene nanoribbon/h-BN heterojunction (11-AGNR/h-BN), which are carried out using the density functional theory (DFT) method and the non-equilibrium Green's function (NEGF) technique. Since 11-AGNR belongs to the conductive (3n-1)-family of AGNR, both are metallic nanomaterials with two transverse arrays of h-BN, which is a wide-gap semi-conductor. The two h-BN arrays act as double barriers. The transmission functions (TF) and I-[Formula: see text] characteristics of GS/h-BN and 11-AGNR/h-BN are calculated by DFT and NEGF, and they show that quantum double barrier tunneling occurs. The TF becomes very spiky in both materials, and it leads to step-wise I-[Formula: see text] characteristics rather than negative resistance, which is the typical behavior of double barriers in semiconductors. The results of our first principle calculations are also compared with 1D Dirac equation model for the double barrier system. The model explains most of the peaks of the transmission functions nearby the Fermi energy quite well. They are due to quantum tunneling.

Analytical investigation of microwave resonances of a curling probe for low and high-pressure plasma diagnostics

NASA Astrophysics Data System (ADS)

Arshadi, Ali; Brinkmann, Ralf Peter

2017-01-01

The concept of ‘active plasma resonance spectroscopy’ (APRS) has attracted greater interest in recent years as an established plasma diagnostic technique. The APRS describes a class of related methods utilizing the intrinsic ability of plasma to resonate at or near the electron plasma frequency {ω\\text{pe}} . The Curling probe (CP) as a novel realization of the APRS idea, is a miniaturized spiral slot embedded flatly in the chamber wall. Consequently, a plasma diagnostic technique with minimum disturbance and without metal contamination can be developed. To measure the plasma parameters the CP is fed with a weak frequency-swept signal from the exterior of the plasma chamber by a network analyzer which also records the response of the plasma versus the frequency. The resonance behavior is strongly dependent on the electron density and the gas pressure. The CP has also the advantage of resonating at a frequency greater than {ω\\text{pe}} which is dependent on the spiral’s length. The double resonance characteristic gives the CP the ability to be applied in varying plasma regimes. Assuming that the spiralization does not have a considerable effect on the resonances, a ‘straightened’ infinite length CP has recently been investigated (Arshadi and Brinkmann 2016 Plasma Sources Sci. Technol. 25 045014) to obtain the surface wave resonances. This work generalizes the approach and models the CP by a rectangular slot-type resonator located between plasma and quartz. Cold plasma theory and Maxwell’s equations are utilized to compute the electromagnetic fields propagating into the plasma by the diffraction of an incident plane wave at the slot. A mathematical model is employed and both kinds of resonances are derived. The analytical study of this paper shows good agreement with the numerical results of the probe inventors.

Examination of the possible enhancement of neutrinoless double-electron capture in 78Kr

NASA Astrophysics Data System (ADS)

Bustabad, S.; Bollen, G.; Brodeur, M.; Lincoln, D. L.; Novario, S. J.; Redshaw, M.; Ringle, R.; Schwarz, S.

2013-09-01

Penning-trap mass spectrometry was used at the Low-Energy Beam and Ion Trap (LEBIT) facility at the National Superconducting Cyclotron Laboratory (NSCL) to investigate 78Kr, a candidate for resonantly enhanced neutrinoless double-electron capture (0νECEC). The newly determined Q value of 2847.75 (27) keV is 1.4 keV greater than the value from the most recent atomic mass evaluation [Chin. Phys. C1674-113710.1088/1674-1137/36/12/003 36, 1603 (2012)], a change of two sigma, and the uncertainty has been reduced by a factor of three. The change in the Q value shifts allowed 0νECEC in 78Kr further from resonant enhancement. With the improved determination of the Q value, all known excited states can now be confidently excluded from possible 78Se candidates that could lead to resonantly enhanced 0νECEC.

Structural parameter effect of porous material on sound absorption performance of double-resonance material

NASA Astrophysics Data System (ADS)

Fan, C.; Tian, Y.; Wang, Z. Q.; Nie, J. K.; Wang, G. K.; Liu, X. S.

2017-06-01

In view of the noise feature and service environment of urban power substations, this paper explores the idea of compound impedance, fills some porous sound-absorption material in the first resonance cavity of the double-resonance sound-absorption material, and designs a new-type of composite acoustic board. We conduct some acoustic characterizations according to the standard test of impedance tube, and research on the influence of assembly order, the thickness and area density of the filling material, and back cavity on material sound-absorption performance. The results show that the new-type of acoustic board consisting of aluminum fibrous material as inner structure, micro-porous board as outer structure, and polyester-filled space between them, has good sound-absorption performance for low frequency and full frequency noise. When the thickness, area density of filling material and thickness of back cavity increase, the sound absorption coefficient curve peak will move toward low frequency.

Amino acid selective unlabeling for sequence specific resonance assignments in proteins

PubMed Central

Krishnarjuna, B.; Jaipuria, Garima; Thakur, Anushikha

2010-01-01

Sequence specific resonance assignment constitutes an important step towards high-resolution structure determination of proteins by NMR and is aided by selective identification and assignment of amino acid types. The traditional approach to selective labeling yields only the chemical shifts of the particular amino acid being selected and does not help in establishing a link between adjacent residues along the polypeptide chain, which is important for sequential assignments. An alternative approach is the method of amino acid selective ‘unlabeling’ or reverse labeling, which involves selective unlabeling of specific amino acid types against a uniformly 13C/15N labeled background. Based on this method, we present a novel approach for sequential assignments in proteins. The method involves a new NMR experiment named, {12COi–15Ni+1}-filtered HSQC, which aids in linking the 1HN/15N resonances of the selectively unlabeled residue, i, and its C-terminal neighbor, i + 1, in HN-detected double and triple resonance spectra. This leads to the assignment of a tri-peptide segment from the knowledge of the amino acid types of residues: i − 1, i and i + 1, thereby speeding up the sequential assignment process. The method has the advantage of being relatively inexpensive, applicable to 2H labeled protein and can be coupled with cell-free synthesis and/or automated assignment approaches. A detailed survey involving unlabeling of different amino acid types individually or in pairs reveals that the proposed approach is also robust to misincorporation of 14N at undesired sites. Taken together, this study represents the first application of selective unlabeling for sequence specific resonance assignments and opens up new avenues to using this methodology in protein structural studies. Electronic supplementary material The online version of this article (doi:10.1007/s10858-010-9459-z) contains supplementary material, which is available to authorized users. PMID:21153044

Miniaturization and Optimization of Nanoscale Resonant Oscillators

DTIC Science & Technology

2013-09-07

carried out over a range of core sizes. Using a double 4-f imaging system in conjunction with a pump filter ( Semrock RazorEdge long wavelength pass...Using a double 4-f imaging system in conjunction with a pump filter ( Semrock RazorEdge long wavelength pass), the samples are imaged onto either an

Local modulation of double optomechanically induced transparency and amplification.

PubMed

Yang, Q; Hou, B P; Lai, D G

2017-05-01

We consider the probe absorption properties in a mechanically coupled optomechanical system in which the two coupled nanomechanical oscillators are driven by the time-dependent forces, respectively. It is found that the mechanical interaction splits the transparency window for a usual single-mode optomechanical system into two parts and then leads to appearance of the double optomechanically induced transparency. The distance between the two transparency positions (the frequency for the maximal transparency) is determined by the mechanical interaction amplitude. This can be explained by using optomechanical dressed-mode picture which is analogue to the interacting dark resonances in coherent atoms. When the mechanical resonators are driven by the external forces, the transparencies in the double-transparency spectrum can be increased into amplifications or be suppressed by tuning the amplitude of the forces. Additionally, it is shown that the double transparencies or the amplifications oscillate with the initial phases of the forces with a period of 2π. These investigations will be useful for more flexible controllability of multi-channel optical communication based on the optomechanical systems.

Au-Ag-Au double shell nanoparticles-based localized surface plasmon resonance and surface-enhanced Raman scattering biosensor for sensitive detection of 2-mercapto-1-methylimidazole.

PubMed

Liao, Xue; Chen, Yanhua; Qin, Meihong; Chen, Yang; Yang, Lei; Zhang, Hanqi; Tian, Yuan

2013-12-15

In this paper, Au-Ag-Au double shell nanoparticles were prepared based on the reduction of the metal salts HAuCl4 and AgNO3 at the surface of seed particles. Due to the synergistic effect between Au and Ag, the hybrid nanoparticles are particularly stable and show excellent performances on the detection of 2-mercapto-1-methylimidazole (methimazole). The binding of target molecule at the surface of Au-Ag-Au double shell nanoparticles was demonstrated based on both localized surface plasmon resonance (LSPR) and surface-enhanced Raman scattering (SERS) spectra. The LSPR intensity is directly proportional to the methimazole concentration in the range of 0.10-3.00×10(-7) mol L(-1). The SERS spectrum can be applied in identification of methimazole molecule. The LSPR coupled with SERS based on the Au-Ag-Au double shell nanoparticles would be very attractive for the quantitative determination and qualitative analysis of the analytes in medicines. © 2013 Elsevier B.V. All rights reserved.

Probing Fe-V Bonding in a C3-Symmetric Heterobimetallic Complex.

PubMed

Greer, Samuel M; McKay, Johannes; Gramigna, Kathryn M; Thomas, Christine M; Stoian, Sebastian A; Hill, Stephen

2018-04-30

Direct metal-metal bonding of two distinct first-row transition metals remains relatively unexplored compared to their second- and third-row heterobimetallic counterparts. Herein, a recently reported Fe-V triply bonded species, [V( i PrNPPh 2 ) 3 FeI] (1; Kuppuswamy, S.; Powers, T. M.; Krogman, J. P.; Bezpalko, M. W.; Foxman, B. M.; Thomas, C. M. Vanadium-iron complexes featuring metal-metal multiple bonds. Chem. Sci. 2013, 4, 3557-3565), is investigated using high-frequency electron paramagnetic resonance, field- and temperature-dependent 57 Fe nuclear gamma resonance (Mössbauer) spectroscopy, and high-field electron-electron double resonance detected nuclear magnetic resonance. From the use of this suite of physical methods, we have assessed the electronic structure of 1. These studies allow us to establish the effective g̃ tensors as well as the Fe/V electro-nuclear hyperfine interaction tensors of the spin S = 1 / 2 ground state. We have rationalized these tensors in the context of ligand field theory supported by quantum chemical calculations. This theoretical analysis suggests that the S = 1 / 2 ground state originates from a single unpaired electron predominately localized on the Fe site.

Mechanically tunable terahertz graphene plasmonics using soft metasurface

NASA Astrophysics Data System (ADS)

Wang, Li; Liu, Xin; Zang, Jianfeng

2016-12-01

This letter presents a new approach to continuously tune the resonances of graphene plasmons in terahertz soft metasurface. The continuous tunability of plasmon resonance is either unachievable in conventional plasmonic materials like noble metals or requires gate voltage regulation in graphene. Here we investigate a simplest form of terahertz metasurface, graphene nanoribbon arrays (GNRAs), and demonstrate the graphene plasmon resonance modes can be tailored by mechanical deformation of the elastomeric substrate using finite element method (FEM). By integrating the electric doping with substrate deformation, we have managed to tune the resonance wavelength from 13.7 to 50.6 μm. The 36.9 μm tuning range is nearly doubled compared with that by electric doping regulation only. Moreover, we observe the plasmon coupling effect in GNRAs on waved substrate and its evolution with substrate curvature. A new decoupling mechanism enabled by the out-of-plane separation of the adjacent ribbons is revealed. The out-of-plane setup of plasmonic components extends the fabrication of plasmonic devices into three-dimensional space, which simultaneously increases the nanoribbon density and decreases the coupling strength. Our findings provide an additional degree of freedom to design reconfigurable metasurfaces and metadevices.

Further refinement of 17O TRAPDOR NMR methods for determining oxygen speciation in multi-component oxide glasses

NASA Astrophysics Data System (ADS)

LaComb, M.; Stebbins, J. F.

2017-12-01

Solid state nuclear magnetic resonance (NMR) spectroscopy has often been utilized to determine network speciation in oxide glasses, typically using NMR-active nuclides such as 11B, 27Al and 17O. High field strength magnets allow for visible separation between bridging (BO) and non-bridging oxygens (NBO) in 17O magic-angle spinning (MAS) NMR spectra, but many questions remain due to limited ability to directly observe NBO associated with silicon, boron or aluminum in ternary glass systems with MAS NMR techniques. Recent studies have utilized the combination of 17O{27Al} and 17O{11B} TRAnsfer of Population in DOuble-Resonance (TRAPDOR) NMR to attempt to separate out resonances for these different bridging and non-bridging oxygen species in multicomponent calcium aluminosilicate and aluminoborosilicate glasses and rare-earth aluminoborosilicates. With improved technology and better resolution of spectral components we were able to expand this study to a wider range of calcium aluminosilicate, aluminoborate and aluminoborosilicate glasses and further separate out resonances for both bridging and non-bridging oxygens coordinated with aluminum, boron and/or silicon cations in these glasses.

Operation of the CAPRICE electron cyclotron resonance ion source applying frequency tuning and double frequency heating.

PubMed

Maimone, F; Tinschert, K; Celona, L; Lang, R; Mäder, J; Rossbach, J; Spädtke, P

2012-02-01

The properties of the electromagnetic waves heating the electrons of the ECR ion sources (ECRIS) plasma affect the features of the extracted ion beams such as the emittance, the shape, and the current, in particular for higher charge states. The electron heating methods such as the frequency tuning effect and the double frequency heating are widely used for enhancing the performances of ECRIS or even for the routine operation during the beam production. In order to better investigate these effects the CAPRICE ECRIS has been operated using these techniques. The ion beam properties for highly charged ions have been measured with beam diagnostic tools. The reason of the observed variations of this performance can be related to the different electromagnetic field patterns, which are changing inside the plasma chamber when the frequency is varying.

High power single-frequency and frequency-doubled laser with active compensation for the thermal lens effect of terbium gallium garnet crystal.

PubMed

Yin, Qiwei; Lu, Huadong; Su, Jing; Peng, Kunchi

2016-05-01

The thermal lens effect of terbium gallium garnet (TGG) crystal in a high power single-frequency laser severely limits the output power and the beam quality of the laser. By inserting a potassium dideuterium phosphate (DKDP) slice with negative thermo-optical coefficient into the laser resonator, the harmful influence of the thermal lens effect of the TGG crystal can be effectively mitigated. Using this method, the stable range of the laser is broadened, the bistability phenomenon of the laser during the process of changing the pump power is completely eliminated, the highest output power of an all-solid-state continuous-wave intracavity-frequency-doubling single-frequency laser at 532 nm is enhanced to 30.2 W, and the beam quality of the laser is significantly improved.

Modelling the nonlinear behaviour of double walled carbon nanotube based resonator with curvature factors

NASA Astrophysics Data System (ADS)

Patel, Ajay M.; Joshi, Anand Y.

2016-10-01

This paper deals with the nonlinear vibration analysis of a double walled carbon nanotube based mass sensor with curvature factor or waviness, which is doubly clamped at a source and a drain. Nonlinear vibrational behaviour of a double-walled carbon nanotube excited harmonically near its primary resonance is considered. The double walled carbon nanotube is harmonically excited by the addition of an excitation force. The modelling involves stretching of the mid plane and damping as per phenomenon. The equation of motion involves four nonlinear terms for inner and outer tubes of DWCNT due to the curved geometry and the stretching of the central plane due to the boundary conditions. The vibrational behaviour of the double walled carbon nanotube with different surface deviations along its axis is analyzed in the context of the time response, Poincaré maps and Fast Fourier Transformation diagrams. The appearance of instability and chaos in the dynamic response is observed as the curvature factor on double walled carbon nanotube is changed. The phenomenon of Periodic doubling and intermittency are observed as the pathway to chaos. The regions of periodic, sub-harmonic and chaotic behaviour are clearly seen to be dependent on added mass and the curvature factors in the double walled carbon nanotube. Poincaré maps and frequency spectra are used to explicate and to demonstrate the miscellany of the system behaviour. With the increase in the curvature factor system excitations increases and results in an increase of the vibration amplitude with reduction in excitation frequency.

Proper Resonance Depiction of Acylium Cation: A High-Level and Student Computational Investigation

ERIC Educational Resources Information Center

Esselman, Brian J.; Hill, Nicholas J.

2015-01-01

The electronic and molecular structure of the acylium cation ([CH[subscript 3]CO][superscript +], 1) receives varied treatment in undergraduate textbooks and online resources. The overall structure of 1 is typically represented as an equal combination of resonance structures containing C-O triple and double bonds, the latter structure occasionally…

Double polarisation experiments in meson photoproduction

NASA Astrophysics Data System (ADS)

Hartmann, Jan

2016-11-01

One of the remaining challenges within the standard model is to gain a good understanding of QCD in the non-perturbative regime. A key step towards this aim is baryon spectroscopy, investigating the spectrum and the properties of baryon resonances. To gain access to resonances with small πN partial width, photoproduction experiments provide essential information. Partial wave analyses need to be performed to extract the contributing resonances. Here, a complete experiment is required to unambiguously determine the contributing amplitudes. This involves the measurement of carefully chosen single and double polarisation observables. In a joint endeavour by MAMI, ELSA, and Jefferson Laboratory, a new generation of experiments with polarised beams, polarised proton and neutron targets, and 4π particle detectors have been performed in recent years. Many results of unprecedented quality were recently published by all three experiments, and included by the various partial wave analysis groups in their analyses, leading to substantial improvements, e.g. a more precise determination of resonance parameters. An overview of recent results is given, with an emphasis on results from the CBELSA/TAPS experiment, and their impact on our understanding of the nucleon excitation spectrum is discussed.

Excited Nucleons and Hadron Structure - Proceedings of the Nstar 2000 Conference

NASA Astrophysics Data System (ADS)

Burkert, V. D.; Elouadrhiri, L.; Kelly, J. J.; Minehart, R. C.

The Table of Contents for the book is as follows: * Probing the Structure of Nucleons in the Resonance Region * Pion Photoproduction Results from MAMI * Pion Production and Compton Scattering at LEGS * Electroproduction Multipoles from ELSA * Baryon Resonance Production at Jefferson Lab at High Q2 * A Dynamical Model for the Resonant Multipoles and the Δ Structure * Relations between N and Δ Electromagnetic Form Factors * Measurement of the Recoil Polarization in the [p(ěc e ,{e^prime}ěc p ){π ^0}] Reaction at the Energy of the Δ(1232) Resonance * Electroproduction Results from CLAS * S11 (1535) Resonance Production at Jefferson Lab at High Q2 * η and η' Electro- and Photoproduction with the CEBAF Large Acceptance Spectrometer * η Production in Hadronic Interactions * Electromagnetic Production of η and η' Mesons * The Crystal Barrel Experiment at ELSA * Measurement of π-p → Neutrals Using the Crystal Ball * π+π0 and η Photoproduction at GRAAL * Partial Wave Analysis of Pion Photoproduction with Constraints from Fixed-t Dispersion Relations * N* Resonances in e+e- Collisions at BEPC * What is the Structure of the Roper Resonance? * Hybrid Baryon Signatures * Mixing Angles Determination via the Process γp → ηp * SU(6) Breaking Effects in the Nucleon Elastic Electromagnetic Form Factors * The Hypercentral Constituent Quark Model * Baryon Resonance Decays Within Constituent Quark Models * Pion Production Model - Connection between Dynamics and Quark Models * N* Investigation via Two Pion Electroproduction with the CLAS Detector at Jefferson Laboratory * Isobar Model for Studies of N* Excitation in Charged Double Pion Production by Real and Virtual Photons * Double Pion Photoproduction in the Second Resonance Region * CLAS Electroproduction of ω(783) Mesons * Electromagnetic Production of Vector Mesons at Low Energies * Polarized Target Developments for GRAAL and Prospects * Analytic Structure of a Multichannel Model * Missing Nucleon Resonances in Kaon Production with Pions and Photons * Hyperon Electroproduction with CLAS * From Bjorken to Drell-Hearn-Gerasimov Sum Rules * GDH Measurements at Mainz * Double Polarization Measurements in Inclusive Inelastic e - p Scattering * Measurement of Inclusive Spin Asymmetries and Sum Rules on 3He and the Neutron * Polarization and Out-of-Plane Responses in Pion and ETA Electroproduction * Polarization Observables in π+ Electroproduction with CLAS * Pion Electroproduction on the Nucleon and the Generalized GDH Sum Rule * Virtual Compton Scattering in the Resonance Region * What We Know about the Theoretical Foundation of Duality in Electron Scattering * Hadron Structure in Lattice QCD: Exploring the Gluon Wave Functional * N* Spectrum in Lattice QCD * Baryon Spectrum in the Large Nc Limit * Deeply Virtual Photon and Meson Electroproduction * Why N*'s are Important * Participant List

Ultrasensitive displacement sensor based on tunable horn-shaped resonators

NASA Astrophysics Data System (ADS)

Tian, Ying; Wu, Jiong; Yu, Le; Yang, Helin; Huang, Xiaojun

2018-04-01

In this paper, we proposed a novel double-deck displacement sensor with a high linearity based on tunable horn-shaped resonators. The designed sensor included two substrate layers etched with copper metallization in various shapes. When the upper trip-type resonator layer has a relative displacement to the bottom horn-shaped resonator layer, the resonance frequency of the sensor is redshift. High sensitivity of the sensor is around 207.2 MHz mm-1 with 4 mm linear dynamic range. We fabricate the sample of the proposed displacement sensor, in addition the simulated results are verified by experiment. The proposed displacement sensor is appropriate for using MEMS technology in further miniaturization.

Nitrogen-containing species in the structure of the synthesized nano-hydroxyapatite

NASA Astrophysics Data System (ADS)

Gafurov, M.; Biktagirov, T.; Yavkin, B.; Mamin, G.; Filippov, Y.; Klimashina, E.; Putlayev, V.; Orlinskii, S.

2014-04-01

Synthesized by the wet chemical precipitation technique, hydroxyapatite (HAp) powders with the sizes of the crystallites of 20-50 nm and 1 μm were analyzed by different analytical methods. By means of electron paramagnetic resonance (EPR) it is shown that during the synthesis process nitrate anions from the reagents (byproducts) could incorporate into the HAp structure. The relaxation times and EPR parameters of the stable axially symmetric NO{3/2-} paramagnetic centers detected after X-ray irradiation are measured with high accuracy. Analyses of high-frequency (95 GHz) electron-nuclear double resonance spectra from 1H and 31P nuclei and ab initio density functional theory calculations allow suggesting that the paramagnetic centers and nitrate anions as the precursors of NO{3/2-} radicals preferably occupy PO{4/3-} site in the HAp structure.

Gravity localization in sine-Gordon braneworlds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cruz, W.T., E-mail: wilamicruz@gmail.com; Maluf, R.V., E-mail: r.v.maluf@fisica.ufc.br; Sousa, L.J.S., E-mail: luisjose@fisica.ufc.br

2016-01-15

In this work we study two types of five-dimensional braneworld models given by sine-Gordon potentials. In both scenarios, the thick brane is generated by a real scalar field coupled to gravity. We focus our investigation on the localization of graviton field and the behaviour of the massive spectrum. In particular, we analyse the localization of massive modes by means of a relative probability method in a Quantum Mechanics context. Initially, considering a scalar field sine-Gordon potential, we find a localized state to the graviton at zero mode. However, when we consider a double sine-Gordon potential, the brane structure is changedmore » allowing the existence of massive resonant states. The new results show how the existence of an internal structure can aid in the emergence of massive resonant modes on the brane.« less

New Constraints on Gliese 876—Exemplar of Mean-motion Resonance

NASA Astrophysics Data System (ADS)

Millholland, Sarah; Laughlin, Gregory; Teske, Johanna; Butler, R. Paul; Burt, Jennifer; Holden, Bradford; Vogt, Steven; Crane, Jeffrey; Shectman, Stephen; Thompson, Ian

2018-03-01

Gliese 876 harbors one of the most dynamically rich and well-studied exoplanetary systems. The nearby M4V dwarf hosts four known planets, the outer three of which are trapped in a Laplace mean-motion resonance. A thorough characterization of the complex resonant perturbations exhibited by the orbiting planets, and the chaotic dynamics therein, is key to a complete picture of the system’s formation and evolutionary history. Here we present a reanalysis of the system using 6 yr of new radial velocity (RV) data from four instruments. These new data augment and more than double the size of the decades-long collection of existing velocity measurements. We provide updated estimates of the system parameters by employing a computationally efficient Wisdom–Holman N-body symplectic integrator, coupled with a Gaussian process (GP) regression model to account for correlated stellar noise. Experiments with synthetic RV data show that the dynamical characterization of the system can differ depending on whether a white-noise or correlated-noise model is adopted. Despite there being a region of stability for an additional planet in the resonant chain, we find no evidence for one. Our new parameter estimates place the system even deeper into resonance than previously thought and suggest that the system might be in a low-energy, quasi-regular double apsidal corotation resonance. This result and others will be used in a subsequent study on the primordial migration processes responsible for the formation of the resonant chain.

Comparative study of sub-micrometer polymeric structures: Dot-arrays, linear and crossed gratings generated by UV laser based two-beam interference, as surfaces for SPR and AFM based bio-sensing

NASA Astrophysics Data System (ADS)

Csete, M.; Sipos, Á.; Kőházi-Kis, A.; Szalai, A.; Szekeres, G.; Mathesz, A.; Csákó, T.; Osvay, K.; Bor, Zs.; Penke, B.; Deli, M. A.; Veszelka, Sz.; Schmatulla, A.; Marti, O.

2007-12-01

Two-dimensional gratings are generated on poly-carbonate films spin-coated onto thin gold-silver bimetallic layers by two-beam interference method. Sub-micrometer periodic polymer dots and stripes are produced illuminating the poly-carbonate surface by p- and s-polarized beams of a frequency quadrupled Nd:YAG laser, and crossed gratings are generated by rotating the substrates between two sequential treatments. It is shown by pulsed force mode atomic force microscopy that the mean value of the adhesion is enhanced on the dot-arrays and on the crossed gratings. The grating-coupling on the two-dimensional structures results in double peaks on the angle dependent resonance curves of the surface plasmons excited by frequency doubled Nd:YAG laser. The comparison of the resonance curves proves that a surface profile ensuring minimal undirected scattering is required to optimize the grating-coupling, in addition to the minimal modulation amplitude, and to the optimal azimuthal orientation. The secondary minima are the narrowest in presence of linear gratings on multi-layers having optimized composition, and on crossed structures consisting of appropriately oriented polymer stripes. The large coupling efficiency and adhesion result in high detection sensitivity on the crossed gratings. Bio-sensing is realized by monitoring the rotated-crossed grating-coupled surface plasmon resonance curves, and detecting the chemical heterogeneity by tapping-mode atomic force microscopy. The interaction of Amyloid-β peptide, a pathogenetic factor in Alzheimer disease, with therapeutical molecules is demonstrated.

Stochastic P-bifurcation and stochastic resonance in a noisy bistable fractional-order system

NASA Astrophysics Data System (ADS)

Yang, J. H.; Sanjuán, Miguel A. F.; Liu, H. G.; Litak, G.; Li, X.

2016-12-01

We investigate the stochastic response of a noisy bistable fractional-order system when the fractional-order lies in the interval (0, 2]. We focus mainly on the stochastic P-bifurcation and the phenomenon of the stochastic resonance. We compare the generalized Euler algorithm and the predictor-corrector approach which are commonly used for numerical calculations of fractional-order nonlinear equations. Based on the predictor-corrector approach, the stochastic P-bifurcation and the stochastic resonance are investigated. Both the fractional-order value and the noise intensity can induce an stochastic P-bifurcation. The fractional-order may lead the stationary probability density function to turn from a single-peak mode to a double-peak mode. However, the noise intensity may transform the stationary probability density function from a double-peak mode to a single-peak mode. The stochastic resonance is investigated thoroughly, according to the linear and the nonlinear response theory. In the linear response theory, the optimal stochastic resonance may occur when the value of the fractional-order is larger than one. In previous works, the fractional-order is usually limited to the interval (0, 1]. Moreover, the stochastic resonance at the subharmonic frequency and the superharmonic frequency are investigated respectively, by using the nonlinear response theory. When it occurs at the subharmonic frequency, the resonance may be strong and cannot be ignored. When it occurs at the superharmonic frequency, the resonance is weak. We believe that the results in this paper might be useful for the signal processing of nonlinear systems.

The determination of pair-distance distribution by double electron-electron resonance: regularization by the length of distance discretization with Monte Carlo calculations

NASA Astrophysics Data System (ADS)

Dzuba, Sergei A.

2016-08-01

Pulsed double electron-electron resonance technique (DEER, or PELDOR) is applied to study conformations and aggregation of peptides, proteins, nucleic acids, and other macromolecules. For a pair of spin labels, experimental data allows for the determination of their distance distribution function, P(r). P(r) is derived as a solution of a first-kind Fredholm integral equation, which is an ill-posed problem. Here, we suggest regularization by increasing the distance discretization length to its upper limit where numerical integration still provides agreement with experiment. This upper limit is found to be well above the lower limit for which the solution instability appears because of the ill-posed nature of the problem. For solving the integral equation, Monte Carlo trials of P(r) functions are employed; this method has an obvious advantage of the fulfillment of the non-negativity constraint for P(r). The regularization by the increasing of distance discretization length for the case of overlapping broad and narrow distributions may be employed selectively, with this length being different for different distance ranges. The approach is checked for model distance distributions and for experimental data taken from literature for doubly spin-labeled DNA and peptide antibiotics.

Quantitative structure parameters from the NMR spectroscopy of quadrupolar nuclei

DOE PAGES

Perras, Frederic A.

2015-12-15

Here, nuclear magnetic resonance (NMR) spectroscopy is one of the most important characterization tools in chemistry, however, 3/4 of the NMR active nuclei are underutilized due to their quadrupolar nature. This short review centers on the development of methods that use solid-state NMR of quadrupolar nuclei for obtaining quantitative structural information. Namely, techniques using dipolar recoupling as well as the resolution afforded by double-rotation are presented for the measurement of spin–spin coupling between quadrupoles, enabling the measurement of internuclear distances and connectivities.

Sensitive and simultaneous surface plasmon resonance detection of free and p53-bound MDM2 proteins from human sarcomas.

PubMed

Wu, Ling; Tang, Hailin; Hu, Shengqiang; Xia, Yonghong; Lu, Zhixuan; Fan, Yujuan; Wang, Zixiao; Yi, Xinyao; Zhou, Feimeng; Wang, Jianxiu

2018-04-30

Murine double minute 2 (MDM2) is an oncoprotein mediating the degradation of the tumor suppressor p53 protein. The physiological levels of MDM2 protein are closely related to malignant transformation and tumor growth. In this work, the simultaneous and label-free determination of free and p53-bound MDM2 proteins from sarcoma tissue extracts was conducted using a dual-channel surface plasmon resonance (SPR) instrument. Free MDM2 protein was measured in one fluidic channel covered with the consensus double-stranded (ds)-DNA/p53 conjugate, while MDM2 bound to p53 was captured by the consensus ds-DNA immobilized onto the other channel. To achieve higher sensitivity and to confirm specificity, an MDM2-specific monoclonal antibody (2A10) was used to recognize both the free and p53-bound MDM2 proteins. The resultant method afforded a detection limit of 0.55 pM of MDM2. The amenability of the method to the analysis of free and p53-bound MDM2 proteins was demonstrated for normal and sarcoma tissue extracts from three patients. Our data reveal that both free and total MDM2 (free and bound forms combined) proteins from sarcoma tissue extracts are of much higher concentrations than those from normal tissue extracts and the p53-bound MDM2 protein only constitutes a small fraction of the total MDM2 concentration. In comparison with enzyme-linked immunosorbent assay (ELISA), the proposed method possesses higher sensitivity, is more cost-effective, and is capable of determining free and p53-bound MDM2 proteins in clinical samples.

Bilayer synergetic coupling double negative acoustic metasurface and cloak.

PubMed

Ma, Fuyin; Huang, Meng; Xu, Yicai; Wu, Jiu Hui

2018-04-12

In this paper, we propose a bilayer plate-type lightweight double negative metasurface based on a new synergetic coupling design concept, by which the perfect absorption, double negative bands, free manipulation of phase shifts with a 2π span and acoustic cloak can be successively realized. Firstly, the synergetic behavior between resonant and anti-resonant plates is presented to construct a bilayer unit in which each component respectively provides a pre-defined function in realizing the perfect absorption. Based on this bilayer structure, a double negative band with simultaneously negative effective mass density and bulk modulus is obtained, which, as a metasurface, can obtain continuous phase shifts almost completely covering a 2π range, thus facilitating the design of a three-dimensional (3D) acoustic cloak. In addition, based on this strong sound absorption concept, a two-dimensional (2D) omnidirectional broadband acoustical dark skin, covering between 800 to 6000 Hz, is also demonstrated through the proposed bilayer plate-type structure form. The proposed design concepts and metasurfaces have widespread potential application values in strong sound attenuation, filtering, superlens, imaging, cloak, and extraordinary wave steering, in which the attributes of strong absorption, double negative parameters or continuous phase shifts with full 2π span are required to realize the expected extraordinary physical features.

State-to-state rotational energy-transfer measurements in the nu(2) = 1 state of ammonia by infrared-infrared double resonance

NASA Technical Reports Server (NTRS)

Abel, Bernd; Coy, Stephen L.; Klaassen, Jody J.; Steinfeld, Jeffrey I.

1992-01-01

The state-resolved rotational (R-R, R-T) energy transfer in (N-14)H3 (for NH3-NH3 and NH3-Ar collisions) was studied using an IR double-resonance laser spectroscopic technique. Measurements of both the total rate of depopulation by collisions, and the rates of transfer into specific final rovibrational states (v,J,K) were performed using time-resolved tunable diode laser absorption spectroscopy. A kinetic master-equation analysis of time-resolved level populatons was carried out, yielding state-to-state rate constants and propensity rules for NH3-NH3 and NH3-Ar collisions.

Realizing high-performance metamaterial absorber based on the localized surface plasmon resonance in the terahertz regime

NASA Astrophysics Data System (ADS)

Yunfeng, Lin; Xiaoqi, Hu; Lin, Hu

2018-04-01

A composite structure design metamaterial absorber is designed and simulated. The proposed composite structure consists of a double-hole sub-structure and a double-metallic particle sub-structure. The damping constant of bulk gold layer is optimized to eliminate the adverse effects of the grain boundary and the surface scattering of thin films on the absorption property. Two absorption peaks (A1 = 58%, A2 = 23%) are achieved based on the localized surface plasmon (LSP) modes resonance. Moreover, the plasmonic hybridization phenomenon between LSP modes is found, which leads to the absorption enhancement between two absorption peaks. The proposed metamaterial absorber holds the property of wide-angle incidence.

Phase modulation of mid-infrared radiation in double-quantum-well structures under a lateral electric field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balagula, R. M.; Vinnichenko, M. Ya.; Makhov, I. S.

2017-03-15

The modulation of polarized radiation by GaAs/AlGaAs structures with tunnel-coupled double quantum wells in a strong lateral electric field is studied. The spectra of the variation in the refractive index under a lateral electric field in the vicinity of the intersubband resonance are experimentally investigated.

Faraday anomalous dispersion optical tuners

NASA Technical Reports Server (NTRS)

Wanninger, P.; Valdez, E. C.; Shay, T. M.

1992-01-01

Common methods for frequency stabilizing diode lasers systems employ gratings, etalons, optical electric double feedback, atomic resonance, and a Faraday cell with low magnetic field. Our method, the Faraday Anomalous Dispersion Optical Transmitter (FADOT) laser locking, is much simpler than other schemes. The FADOT uses commercial laser diodes with no antireflection coatings, an atomic Faraday cell with a single polarizer, and an output coupler to form a compound cavity. This method is vibration insensitive, thermal expansion effects are minimal, and the system has a frequency pull in range of 443.2 GHz (9A). Our technique is based on the Faraday anomalous dispersion optical filter. This method has potential applications in optical communication, remote sensing, and pumping laser excited optical filters. We present the first theoretical model for the FADOT and compare the calculations to our experimental results.

Double-quantum resonances and exciton-scattering in coherent 2D spectroscopy of photosynthetic complexes

PubMed Central

Abramavicius, Darius; Voronine, Dmitri V.; Mukamel, Shaul

2008-01-01

A simulation study demonstrates how the nonlinear optical response of the Fenna–Matthews–Olson photosynthetic light-harvesting complex may be explored by a sequence of laser pulses specifically designed to probe the correlated dynamics of double excitations. Cross peaks in the 2D correlation plots of the spectra reveal projections of the double-exciton wavefunctions onto a basis of direct products of single excitons. An alternative physical interpretation of these signals in terms of quasiparticle scattering is developed. PMID:18562293

Carotid artery stenting with double cerebral embolic protection in asymptomatic patients - a diffusion-weighted MRI controlled study.

PubMed

Vuruskan, Ertan; Saracoglu, Erhan; Ergun, Ugur; Poyraz, Fatih; Duzen, İrfan Veysel

2017-01-01

The aim of this study was to compare the simultaneous double-protection method (proximal balloon plus distal filter) with distal-filter protection or proximal-balloon protection alone in asymptomatic patients during carotid artery stenting. 119 consecutive patients were investigated for carotid artery stentings in the extracranial internal carotid artery with the use of distal filters (n = 41, 34.4 %), proximal balloon (MoMa) protection (n = 40, 33.6 %) or double protection (n = 38, 31.9 %). Magnetic resonance imaging (MRI) was performed on all patients before the procedure, and control diffusion-weighted MRI (DW-MRI) was obtained within 24-48 h after the procedure. Procedural data, complications, success rate, major adverse cardiovascular events, and MRI findings were collected. New cerebral high-intensity (HI) lesions were observed in 47 (39.4 %) patients. HI lesions were observed in 22 (53.6 %), 15 (37.5 %), and 10 (26.3 %) of the patients with distal filters, proximal protection, and double protection, respectively (p = 0.004). The average number of HI lesions on DW-MRI was 1.80 in the distal-filter group, 0.90 in the proximal-balloon group, and 0.55 in the double-protection group (p < 0.001). Procedure and fluoroscopy times were slightly longer in the double-protection group compared to the distal- or proximal-protection groups (p = 0.001). The double (proximal plus distal) cerebral embolic protection technique is safe and effective for minimizing the risk of cerebral embolization, even in patients with asymptomatic carotid artery stenosis, despite slightly longer procedure and fluoroscopy times.
.

Macroscopic resonant tunneling in the presence of low frequency noise.

PubMed

Amin, M H S; Averin, Dmitri V

2008-05-16

We develop a theory of macroscopic resonant tunneling of flux in a double-well potential in the presence of realistic flux noise with a significant low-frequency component. The rate of incoherent flux tunneling between the wells exhibits resonant peaks, the shape and position of which reflect qualitative features of the noise, and can thus serve as a diagnostic tool for studying the low-frequency flux noise in SQUID qubits. We show, in particular, that the noise-induced renormalization of the first resonant peak provides direct information on the temperature of the noise source and the strength of its quantum component.

Sound transmission through finite lightweight multilayered structures with thin air layers.

PubMed

Dijckmans, A; Vermeir, G; Lauriks, W

2010-12-01

The sound transmission loss (STL) of finite lightweight multilayered structures with thin air layers is studied in this paper. Two types of models are used to describe the vibro-acoustic behavior of these structures. Standard transfer matrix method assumes infinite layers and represents the plane wave propagation in the layers. A wave based model describes the direct sound transmission through a rectangular structure placed between two reverberant rooms. Full vibro-acoustic coupling between rooms, plates, and air cavities is taken into account. Comparison with double glazing measurements shows that this effect of vibro-acoustic coupling is important in lightweight double walls. For infinite structures, structural damping has no significant influence on STL below the coincidence frequency. In this frequency region, the non-resonant transmission or so-called mass-law behavior dominates sound transmission. Modal simulations suggest a large influence of structural damping on STL. This is confirmed by experiments with double fiberboard partitions and sandwich structures. The results show that for thin air layers, the damping induced by friction and viscous effects at the air gap surfaces can largely influence and improve the sound transmission characteristics.

Pulsed EPR measurements on reaction rate constants for addition of photo-generated radicals to double bonds of diethyl fumarate and diethyl maleate

NASA Astrophysics Data System (ADS)

Takahashi, Hirona; Hagiwara, Kenta; Kawai, Akio

2016-11-01

Addition reaction of photo-generated radicals to double bonds of diethyl fumarate (deF) and diethyl maleate (deM), which are geometrical isomers, was studied by means of time-resolved- (TR-) and pulsed-electron paramagnetic resonance (EPR). Analysis of TR-EPR spectra indicates that adduct radicals from deF and deM should have the same structure. The double bonds of these monomers are converted to single ones by addition reaction, which allows hindered internal rotation to give the same structure of adduct radical. The rate constants for addition reaction of photo-generated radicals were determined by Stern-Volmer analysis of the decay time of electron spin-echo intensity of these radicals measured by the pulsed EPR method. Rate constants for deF were found to be larger than those for deM. This relation is in good consistent with efficiency of polymerisation of deF and deM. Experimentally determined rate constants were evaluated by introducing the addition reaction model on the basis of two important factors enthalpy and polar effects.

ABC effect and resonance d*(2380)

NASA Astrophysics Data System (ADS)

Bashkanov, M.; Clement, H.; Doroshkevich, E.; Skorodko, T.

2017-11-01

A new state in the two-baryon system with mass 2380 MeV and width 80 MeV has been detected in the experiments at the Juelich Cooler Synchrotron (COSY). The new particle denoted now d*(2380) has quantum numbers I( J p ) = 0(3+). The total cross sections for the d and 4He fusion reactions show similar to each other resonance-like energy dependence. The resonance-like structure is sensed in the double-pionic fusion channels and polarized np scattering.

Frequency adjustable MEMS vibration energy harvester

NASA Astrophysics Data System (ADS)

Podder, P.; Constantinou, P.; Amann, A.; Roy, S.

2016-10-01

Ambient mechanical vibrations offer an attractive solution for powering the wireless sensor nodes of the emerging “Internet-of-Things”. However, the wide-ranging variability of the ambient vibration frequencies pose a significant challenge to the efficient transduction of vibration into usable electrical energy. This work reports the development of a MEMS electromagnetic vibration energy harvester where the resonance frequency of the oscillator can be adjusted or tuned to adapt to the ambient vibrational frequency. Micro-fabricated silicon spring and double layer planar micro-coils along with sintered NdFeB micro-magnets are used to construct the electromagnetic transduction mechanism. Furthermore, another NdFeB magnet is adjustably assembled to induce variable magnetic interaction with the transducing magnet, leading to significant change in the spring stiffness and resonance frequency. Finite element analysis and numerical simulations exhibit substantial frequency tuning range (25% of natural resonance frequency) by appropriate adjustment of the repulsive magnetic interaction between the tuning and transducing magnet pair. This demonstrated method of frequency adjustment or tuning have potential applications in other MEMS vibration energy harvesters and micromechanical oscillators.

New developments in high field electron paramagnetic resonance with applications in structural biology

NASA Astrophysics Data System (ADS)

Bennati, Marina; Prisner, Thomas F.

2005-02-01

Recent developments in microwave technologies have led to a renaissance of electron paramagnetic resonance (EPR) due to the implementation of new spectrometers operating at frequencies >=90 GHz. EPR at high fields and high frequencies (HF-EPR) has been established up to THz (very high frequency (VHF) EPR) in continuous wave (cw) operation and up to about 300 GHz in pulsed operation. To date, its most prominent application field is structural biology. This review article first gives an overview of the theoretical basics and the technical aspects of HF-EPR methodologies, such as cw and pulsed HF-EPR, as well as electron nuclear double resonance at high fields (HF-ENDOR). In the second part, the article illustrates different application areas of HF-EPR in studies of protein structure and function. In particular, HF-EPR has delivered essential contributions to disentangling complex spectra of radical cofactors or reaction intermediates in photosynthetic reaction centres, radical enzymes (such as ribonucleotide reductase) and in metalloproteins. Furthermore, HF-EPR combined with site-directed spin labelling in membranes and soluble proteins provides new methods of investigating complex molecular dynamics and intermolecular distances.

Keldysh meets Lindblad: Correlated Gain and Loss in Higher Order Perturbation Theory

NASA Astrophysics Data System (ADS)

Stace, Tom; Mueller, Clemens

Motivated by correlated decay processes driving gain, loss and lasing in driven artificial quantum systems, we develop a theoretical technique using Keldysh diagrammatic perturbation theory to derive a Lindblad master equation that goes beyond the usual second order perturbation theory. We demonstrate the method on the driven dissipative Rabi model, including terms up to fourth order in the interaction between the qubit and both the resonator and environment. This results in a large class of Lindblad dissipators and associated rates which go beyond the terms that have previously been proposed to describe similar systems. All of the additional terms contribute to the system behaviour at the same order of perturbation theory. We then apply these results to analyse the phonon-assisted steady-state gain of a microwave field driving a double quantum-dot in a resonator. We show that resonator gain and loss are substantially affected by dephasing- assisted dissipative processes in the quantum-dot system. These additional processes, which go beyond recently proposed polaronic theories, are in good quantitative agreement with experimental observations.

Immobilization of human papillomavirus DNA probe for surface plasmon resonance imaging

NASA Astrophysics Data System (ADS)

Chong, Xinyuan; Ji, Yanhong; Ma, Suihua; Liu, Le; Liu, Zhiyi; Li, Yao; He, Yonghong; Guo, Jihua

2009-08-01

Human papillomavirus (HPV) is a kind of double-stranded DNA virus whose subspecies have diversity. Near 40 kinds of subspecies can invade reproductive organ and cause some high risk disease, such as cervical carcinoma. In order to detect the type of the subspecies of the HPV DNA, we used the parallel scan spectral surface plasmon resonance (SPR) imaging technique, which is a novel type of two- dimensional bio-sensing method based on surface plasmon resonance and is proposed in our previous work, to study the immobilization of the HPV DNA probes on the gold film. In the experiment, four kinds of the subspecies of the HPV DNA (HPV16, HPV18, HPV31, HPV58) probes are fixed on one gold film, and incubate in the constant temperature condition to get a HPV DNA probe microarray. We use the parallel scan spectral SPR imaging system to detect the reflective indices of the HPV DNA subspecies probes. The benefits of this new approach are high sensitive, label-free, strong specificity and high through-put.

Strain induced parametric pumping of a domain wall and its depinning from a notch

NASA Astrophysics Data System (ADS)

Nepal, Rabindra; Gungordu, Utkan; Kovalev, Alexey

Using Thiele's method and detailed micromagnetic simulations, we study resonant oscillation of a domain wall in a notch of a ferromagnetic nanowire due to the modulation of magnetic anisotropy by external AC strain. Such resonant oscillation results from the parametric pumping of domain wall by AC strain at frequency about double the free domain wall oscillation frequency, which is mainly determined by the perpendicular anisotropy and notch geometry. This effect leads to a substantial reduction in depinning field or current required to depin a domain wall from the notch, and offers a mechanism for efficient domain wall motion in a notched nanowire. Our theoretical model accounts for the pinning potential due to a notch by explicitly calculating ferromagnetic energy as a function of notch geometry parameters. We also find similar resonant domain wall oscillations and reduction in the domain wall depinning field or current due to surface acoustic wave in soft ferromagnetic nanowire without uniaxial anisotropy that energetically favors an in-plane domain wall. DOE Early Career Award DE-SC0014189 and DMR- 1420645.

Biomechanical and magnetic resonance imaging evaluation of a single- and double-row rotator cuff repair in an in vivo sheep model.

PubMed

Baums, Mike H; Spahn, Gunter; Buchhorn, Gottfried H; Schultz, Wolfgang; Hofmann, Lars; Klinger, Hans-Michael

2012-06-01

To investigate the biomechanical and magnetic resonance imaging (MRI)-derived morphologic changes between single- and double-row rotator cuff repair at different time points after fixation. Eighteen mature female sheep were randomly assigned to either a single-row treatment group using arthroscopic Mason-Allen stitches or a double-row treatment group using a combination of arthroscopic Mason-Allen and mattress stitches. Each group was analyzed at 1 of 3 survival points (6 weeks, 12 weeks, and 26 weeks). We evaluated the integrity of the cuff repair using MRI and biomechanical properties using a mechanical testing machine. The mean load to failure was significantly higher in the double-row group compared with the single-row group at 6 and 12 weeks (P = .018 and P = .002, respectively). At 26 weeks, the differences were not statistically significant (P = .080). However, the double-row group achieved a mean load to failure similar to that of a healthy infraspinatus tendon, whereas the single-row group reached only 70% of the load of a healthy infraspinatus tendon. No significant morphologic differences were observed based on the MRI results. This study confirms that in an acute repair model, double-row repair may enhance the speed of mechanical recovery of the tendon-bone complex when compared with single-row repair in the early postoperative period. Double-row rotator cuff repair enables higher mechanical strength that is especially sustained during the early recovery period and may therefore improve clinical outcome. Crown Copyright © 2012. Published by Elsevier Inc. All rights reserved.

The use of a selective saturation pulse to suppress t1 noise in two-dimensional 1H fast magic angle spinning solid-state NMR spectroscopy

NASA Astrophysics Data System (ADS)

Robertson, Aiden J.; Pandey, Manoj Kumar; Marsh, Andrew; Nishiyama, Yusuke; Brown, Steven P.

2015-11-01

A selective saturation pulse at fast magic angle spinning (MAS) frequencies (60+ kHz) suppresses t1 noise in the indirect dimension of two-dimensional 1H MAS NMR spectra. The method is applied to a synthetic nucleoside with an intense methyl 1H signal due to triisopropylsilyl (TIPS) protecting groups. Enhanced performance in terms of suppressing the methyl signal while minimising the loss of signal intensity of nearby resonances of interest relies on reducing spin diffusion - this is quantified by comparing two-dimensional 1H NOESY-like spin diffusion spectra recorded at 30-70 kHz MAS. For a saturation pulse centred at the methyl resonance, the effect of changing the nutation frequency at different MAS frequencies as well as the effect of changing the pulse duration is investigated. By applying a pulse of duration 30 ms and nutation frequency 725 Hz at 70 kHz MAS, a good compromise of significant suppression of the methyl resonance combined with the signal intensity of resonances greater than 5 ppm away from the methyl resonance being largely unaffected is achieved. The effectiveness of using a selective saturation pulse is demonstrated for both homonuclear 1H-1H double quantum (DQ)/single quantum (SQ) MAS and 14N-1H heteronuclear multiple quantum coherence (HMQC) two-dimensional solid-state NMR experiments.

Magnetic resonance imaging and magnetic resonance spectroscopy for detection of early Alzheimer's disease.

PubMed

Westman, Eric; Wahlund, Lars-Olof; Foy, Catherine; Poppe, Michaela; Cooper, Allison; Murphy, Declan; Spenger, Christian; Lovestone, Simon; Simmons, Andrew

2011-01-01

Alzheimer's disease is the most common form of neurodegenerative disorder and early detection is of great importance if new therapies are to be effectively administered. We have investigated whether the discrimination between early Alzheimer's disease (AD) and elderly healthy control subjects can be improved by adding magnetic resonance spectroscopy (MRS) measures to magnetic resonance imaging (MRI) measures. In this study 30 AD patients and 36 control subjects were included. High resolution T1-weighted axial magnetic resonance images were obtained from each subject. Automated regional volume segmentation and cortical thickness measures were determined for the images. 1H MRS was acquired from the hippocampus and LCModel was used for metabolic quantification. Altogether, this yielded 58 different volumetric, cortical thickness and metabolite ratio variables which were used for multivariate analysis to distinguish between subjects with AD and Healthy controls. Combining MRI and MRS measures resulted in a sensitivity of 97% and a specificity of 94% compared to using MRI or MRS measures alone (sensitivity: 87%, 76%, specificity: 86%, 83% respectively). Adding the MRS measures to the MRI measures more than doubled the positive likelihood ratio from 6 to 17. Adding MRS measures to a multivariate analysis of MRI measures resulted in significantly better classification than using MRI measures alone. The method shows strong potential for discriminating between Alzheimer's disease and controls.

Microwave emulations and tight-binding calculations of transport in polyacetylene

NASA Astrophysics Data System (ADS)

Stegmann, Thomas; Franco-Villafañe, John A.; Ortiz, Yenni P.; Kuhl, Ulrich; Mortessagne, Fabrice; Seligman, Thomas H.

2017-01-01

A novel approach to investigate the electron transport of cis- and trans-polyacetylene chains in the single-electron approximation is presented by using microwave emulation measurements and tight-binding calculations. In the emulation we take into account the different electronic couplings due to the double bonds leading to coupled dimer chains. The relative coupling constants are adjusted by DFT calculations. For sufficiently long chains a transport band gap is observed if the double bonds are present, whereas for identical couplings no band gap opens. The band gap can be observed also in relatively short chains, if additional edge atoms are absent, which cause strong resonance peaks within the band gap. The experimental results are in agreement with our tight-binding calculations using the nonequilibrium Green's function method. The tight-binding calculations show that it is crucial to include third nearest neighbor couplings to obtain the gap in the cis-polyacetylene.

Quantification of site-city interaction effects on the response of structure under double resonance condition

NASA Astrophysics Data System (ADS)

Kumar, Neeraj; Narayan, Jay Prakash

2018-01-01

This paper presents the site-city interaction (SCI) effects on the response of closely spaced structures under double resonance condition (F_{02{{D}}}^{{S}} = F_{02{{D}}}^{{B}}), where F_{02{{D}}}^{{S}} and F_{02{{D}}}^{{B}} are fundamental frequencies of 2-D structure and 2-D basin, respectively. This paper also presents the development of empirical relations to predict the F_{02{{D}}}^{{B}} of elliptical and trapezoidal basins for both the polarizations of the S wave. Simulated results revealed that F_{02{{D}}}^{{B}} of a 2-D basin very much depends on its geometry, shape ratio and polarization of the incident S wave. The obtained spectral amplification factor (SAF) at F_{02{{D}}}^{{S}} of a standalone structure in a 2-D basin is greater than that in the 1-D case under double resonance condition. A considerable reduction of the fundamental resonance frequency of structures due to the SCI effects is observed for both the polarizations of the S wave. The SAFs at F_{02{{D}}}^{{S}} of closely spaced structures due to SCI effects is larger in the case of SV than SH waves. A splitting of the fundamental-mode frequency bandwidth along with the drastic decrease of SAF due to the SCI effects is obtained. The findings of this paper raise the question concerning the validity of the predicted response of standalone structure based on soil-structure interaction for the design of structures in a 2-D small basin, in an urban environment.

Vlasov simulations of electron acceleration by radio frequency heating near the upper hybrid layer

NASA Astrophysics Data System (ADS)

Najmi, A.; Eliasson, B.; Shao, X.; Milikh, G.; Sharma, A. S.; Papadopoulos, K.

2017-10-01

It is shown by using a combination of Vlasov and test particles simulations that the electron distribution function resulting from energization due to Upper Hybrid (UH) plasma turbulence depends critically on the closeness of the pump wave to the double resonance, defined as ω ≈ ωUH ≈ nωce, where n is an integer. For pump frequencies, away from the double resonance, the electron distribution function is very close to Maxwellian, while as the pump frequency approaches the double resonance, it develops a high energy tail. The simulations show turbulence involving coupling between Lower Hybrid (LH) and UH waves, followed by excitation of Electron Bernstein (EB) modes. For the particular case of a pump with frequency between n = 3 and n = 4, the EB modes cover the range from the first to the 5th mode. The simulations show that when the injected wave frequency is between the 3rd and 4th harmonics of the electron cyclotron frequency, bulk electron heating occurs due to the interaction between the electrons and large amplitude EB waves, primarily on the first EB branch leading to an essentially thermal distribution. On the other hand, when the frequency is slightly above the 4th electron cyclotron harmonic, the resonant interaction is predominantly due to the UH branch and leads to a further acceleration of high-velocity electrons and a distribution function with a suprathermal tail of energetic electrons. The results are consistent with ionospheric experiments and relevant to the production of Artificial Ionospheric Plasma Layers.

Polarized linewidth-controllable double-trapping electromagnetically induced transparency spectra in a resonant plasmon nanocavity

PubMed Central

Wang, Luojia; Gu, Ying; Chen, Hongyi; Zhang, Jia-Yu; Cui, Yiping; Gerardot, Brian D.; Gong, Qihuang

2013-01-01

Surface plasmons with ultrasmall optical mode volume and strong near field enhancement can be used to realize nanoscale light-matter interaction. Combining surface plasmons with the quantum system provides the possibility of nanoscale realization of important quantum optical phenomena, including the electromagnetically induced transparency (EIT), which has many applications in nonlinear quantum optics and quantum information processing. Here, using a custom-designed resonant plasmon nanocavity, we demonstrate polarized position-dependent linewidth-controllable EIT spectra at the nanoscale. We analytically obtain the double coherent population trapping conditions in a double-Λ quantum system with crossing damping, which give two transparent points in the EIT spectra. The linewidths of the three peaks are extremely sensitive to the level spacing of the excited states, the Rabi frequencies and detunings of pump fields, and the Purcell factors. In particular the linewidth of the central peak is exceptionally narrow. The hybrid system may have potential applications in ultra-compact plasmon-quantum devices. PMID:24096943

Spin-orbit coupling and electric-dipole spin resonance in a nanowire double quantum dot.

PubMed

Liu, Zhi-Hai; Li, Rui; Hu, Xuedong; You, J Q

2018-02-02

We study the electric-dipole transitions for a single electron in a double quantum dot located in a semiconductor nanowire. Enabled by spin-orbit coupling (SOC), electric-dipole spin resonance (EDSR) for such an electron can be generated via two mechanisms: the SOC-induced intradot pseudospin states mixing and the interdot spin-flipped tunneling. The EDSR frequency and strength are determined by these mechanisms together. For both mechanisms the electric-dipole transition rates are strongly dependent on the external magnetic field. Their competition can be revealed by increasing the magnetic field and/or the interdot distance for the double dot. To clarify whether the strong SOC significantly impact the electron state coherence, we also calculate relaxations from excited levels via phonon emission. We show that spin-flip relaxations can be effectively suppressed by the phonon bottleneck effect even at relatively low magnetic fields because of the very large g-factor of strong SOC materials such as InSb.

Reflection and backscattering of microwaves under doubling of the plasma density and displacement of the gyroresonance region during electron cyclotron resonance heating of plasma in the l-2M stellarator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Batanov, G. M.; Borzosekov, V. D.; Vasilkov, D. G.

Reflection and backscattering of high-power (400 kW) gyrotron radiation creating and heating plasma at the second harmonic of the electronic cyclotron frequency in the L-2M stellarator have been investigated experimentally. The effect of the displacement of the gyroresonance region from the axis of the plasma column under doubling of the plasma density on the processes of reflection and backscattering of microwave radiation has been examined. A near doubling of short-wavelength (k{sub ⊥} ≈ 30 cm{sup –1}) turbulent density fluctuations squared is observed. The change in the energy confinement time under variations of plasma parameters and characteristics of short-wavelength turbulence ismore » discussed. A discrepancy between the measured values of the reflection coefficient from the electron cyclotron resonance heating region and predictions of the one-dimensional model is revealed.« less

Methods and apparatus for transparent display using up-converting nanoparticles

DOEpatents

Hsu, Chia Wei; Qiu, Wenjun; Zhen, Bo; Shapira, Ofer; Soljacic, Marin

2016-10-04

Disclosed herein are transparent color displays with nanoparticles made with nonlinear materials and/or designed to exhibit optical resonances. These nanoparticles are embedded in or hosted on a transparent substrate, such as a flexible piece of clear plastic or acrylic. Illuminating the nanoparticles with invisible light (e.g., infrared or ultraviolet light) causes them to emit visible light. For example, a rare-earth doped nanoparticle may emit visible light when illuminated simultaneoulsy with a first infrared beam at a first wavelength .lamda..sub.1 and a second infrared beam at a second wavelength .lamda..sub.2. And a frequency-doubling nanoparticle may emit visible light when illuminated with a single infrared beam at the nanoparticle's resonant frequency. Selectively addressing these nanoparticles with appropiately selected pump beams yields visible light emitted from the nanoparticles hosted by the transparent substrate in a desired pattern.

Inversion of the resonance line of Sr/+/ produced by optically pumping Sr atoms

NASA Technical Reports Server (NTRS)

Green, W. R.; Falcone, R. W.

1978-01-01

A description is presented of an experiment which demonstrates the selective production of excited-state ions by an optical absorption from neutrals. An inversion on the resonance line of Sr(+) was produced by laser excitation of a two-electron transition, followed by ionization of one of the excited electrons by the same laser. A pulsed, mode-locked laser operating at 2680 A was used to excite atoms from the Sr ground level. The same laser then ionized the excited atoms. The 2680-A pump beam was generated by frequency doubling the output of a synchronously pumped mode-locked dye laser in a KDP crystal. It is pointed out that the reported results are significant for the construction of vacuum-ultraviolet and X-ray lasers. Many of the proposed methods for making such lasers depend on the selective production of excited-state ions.

A flash photolysis resonance fluorescence investigation of the reaction OH + CH3CCl3 yields H2O + CH2CCl3. [in troposphere

NASA Technical Reports Server (NTRS)

Kurylo, M. J.; Anderson, P. C.; Klais, O.

1979-01-01

The absolute rate constant for the reaction OH + CH3CCl3 yields H2O + CH2CCl3 was determined by the flash photolysis resonance fluorescence method from 253 to 363K. The use of the Arrhenius equation with atmospheric observational data on methyl chloroform nearly doubles the predicted tropospheric OH reaction sink strength for the removal of atmospheric gases whose lifetimes are controlled by OH. The increased use of methyl chloroform instead of the restricted trichloroethylene focused attention to its role in stratospheric ozone depletion, producing modeling analyses to determine the amount of released methyl chloroform which reaches the stratosphere. Since the primary atmospheric loss of CH3CCl3 is considered by reaction with OH radicals, these data are used to compute an average tropospheric OH concentration and the strength of the 'global tropospheric OH reaction sink'.

Laser pumping Cs atom magnetometer of theory research based on gradient tensor measuring

NASA Astrophysics Data System (ADS)

Yang, Zhang; Chong, Kang; Wang, Qingtao; Lei, Cheng; Zheng, Caiping

2011-02-01

At present, due to space exploration, military technology, geological exploration, magnetic navigation, medical diagnosis and biological magnetic fields study of the needs of research and development, the magnetometer is given strong driving force. In this paper, it will discuss the theoretical analysis and system design of laser pumping cesium magnetometer, cesium atomic energy level formed hyperfine structure with the I-J coupling, the hyperfine structure has been further split into Zeeman sublevels for the effects of magnetic field. To use laser pump and RF magnetic field make electrons transition in the hyperfine structure to produce the results of magneto-optical double resonance, and ultimately through the resonant frequency will be able to achieve accurate value of the external magnetic field. On this basis, we further have a discussion about magnetic gradient tensor measuring method. To a large extent, it increases the magnetic field measurement of information.

Statistical properties of Pu 243 , and Pu 242 ( n , γ ) cross section calculation

DOE PAGES

Laplace, T. A.; Zeiser, F.; Guttormsen, M.; ...

2016-01-29

The level density and γ-ray strength function (γSF) of 243Pu have been measured in the quasicontinuum using the Oslo method. Excited states in 243Pu were populated using the 242Pu(d,p) reaction. The level density closely follows the constant-temperature level density formula for excitation energies above the pairing gap. The γSF displays a double-humped resonance at low energy as also seen in previous investigations of actinide isotopes. The structure is interpreted as the scissors resonance and has a centroid of ω SR = 2.42(5) MeV and a total strength of B SR = 10.1(15) μ 2 N, which is in excellent agreementmore » with sum-rule estimates. Lastly, the measured level density and γSF were used to calculate the 242Pu(n,γ) cross section in a neutron energy range for which there were previously no measured data.« less

Effect of self-assembled InAs islands on the interfacial roughness of optical-switched resonant tunneling diode

PubMed Central

2012-01-01

Embedding a quantum dot [QD] layer between the double barriers of resonant tunneling diode [RTD] is proved to be an effective method to increase the sensitivity of QD-RTD single-photon detector. However, the interfacial flatness of this device would be worsened due to the introduction of quantum dots. In this paper, we demonstrate that the interfacial quality of this device can be optimized through increasing the growth temperature of AlAs up barrier. The glancing incidence X-ray reflectivity and the high-resolution transmission electron microscopy measurements show that the interfacial smoothness has been greatly improved, and the photo-luminescence test indicated that the InAs QDs were maintained at the same time. The smoother interface was attributed to the evaporation of segregated indium atoms at InGaAs surface layer. PACS 73.40.GK, 73.23._b, 73.21.La, 74.62.Dh PMID:22333518

Effect of self-assembled InAs islands on the interfacial roughness of optical-switched resonant tunneling diode.

PubMed

Tian, Haitao; Wang, Lu; Shi, Zhenwu; Gao, Huaiju; Zhang, Shuhui; Wang, Wenxin; Chen, Hong

2012-02-14

Embedding a quantum dot [QD] layer between the double barriers of resonant tunneling diode [RTD] is proved to be an effective method to increase the sensitivity of QD-RTD single-photon detector. However, the interfacial flatness of this device would be worsened due to the introduction of quantum dots. In this paper, we demonstrate that the interfacial quality of this device can be optimized through increasing the growth temperature of AlAs up barrier. The glancing incidence X-ray reflectivity and the high-resolution transmission electron microscopy measurements show that the interfacial smoothness has been greatly improved, and the photo-luminescence test indicated that the InAs QDs were maintained at the same time. The smoother interface was attributed to the evaporation of segregated indium atoms at InGaAs surface layer. PACS: 73.40.GK, 73.23._b, 73.21.La, 74.62.Dh.

Dual-angle technique for simultaneous measurement of refractive index and temperature based on a surface plasmon resonance sensor.

PubMed

Luo, Wei; Chen, Sheng; Chen, Lei; Li, Hualong; Miao, Pengcheng; Gao, Huiyi; Hu, Zelin; Li, Miao

2017-05-29

We describe a theoretical model to analyze temperature effects on the Kretschmann surface plasmon resonance (SPR) sensor, and describe a new double-incident angle technique to simultaneously measure changes in refractive index (RI) and temperature. The method uses the observation that output signals obtained from two different incident angles each have a linear dependence on RI and temperature, and are independent. A proof-of-concept experiment using different NaCl concentration solutions as analytes demonstrates the ability of the technique. The optical design is as simple and robust as conventional SPR detection, but provides a way to discriminate between RI-induced and temperature-induced SPR changes. This technique facilitates a way for traditional SPR sensors to detect RI in different temperature environments, and may lead to better design and fabrication of SPR sensors against temperature variation.

Parametric Symmetry Breaking in a Nonlinear Resonator

NASA Astrophysics Data System (ADS)

Leuch, Anina; Papariello, Luca; Zilberberg, Oded; Degen, Christian L.; Chitra, R.; Eichler, Alexander

2016-11-01

Much of the physical world around us can be described in terms of harmonic oscillators in thermodynamic equilibrium. At the same time, the far-from-equilibrium behavior of oscillators is important in many aspects of modern physics. Here, we investigate a resonating system subject to a fundamental interplay between intrinsic nonlinearities and a combination of several driving forces. We have constructed a controllable and robust realization of such a system using a macroscopic doubly clamped string. We experimentally observe a hitherto unseen double hysteresis in both the amplitude and the phase of the resonator's response function and present a theoretical model that is in excellent agreement with the experiment. Our work unveils that the double hysteresis is a manifestation of an out-of-equilibrium symmetry breaking between parametric phase states. Such a fundamental phenomenon, in the most ubiquitous building block of nature, paves the way for the investigation of new dynamical phases of matter in parametrically driven many-body systems and motivates applications ranging from ultrasensitive force detection to low-energy computing memory units.

Polarized micro Raman spectroscopy of bilayer graphene

NASA Astrophysics Data System (ADS)

Moon, Hyerim; Yoon, Duhee; Son, Young-Woo; Cheong, Hyeonsik

2009-03-01

The frequency of Raman 2D band of the graphite depends on the excitation laser energy. This phenomenon is explained with double resonance Raman process. In polarized micro-Raman spectroscopy of single layer graphene, Raman G band (˜1586 cm-1) is isotropic, and 2D band (˜2686 cm-1) strongly depends on relative polarizations of the incident and scattered photons. This strong polarization dependence originates from inhomogeneous optical absorption and emission mediated by resonant electron-phonon interaction. In bi-layer graphene, Raman 2D band can be decomposed into four Lorenztian peaks which can be interpreted in terms of the four transition paths in the double resonance Raman process. We investigated the polarization dependence of each Lorenztian peak in the Raman 2D band of bi-layer graphene for different excitation laser energies. Strong polarization dependence of the Raman 2D band, similar to the case of single layer graphene, is observed. The excitation energy dependence of the polarized Raman scattering is analyzed in terms of the band structure of bi-layer graphene.

Double cross-polarization MAS NMR in the assignment of abundant-spin resonances: ¹⁹F-{²⁹Si}-¹⁹F FBCP/MAS NMR of fluoride ions incorporated in calcium silicate hydrate (C-S-H) phases.

PubMed

Tran, Thuan T; Bildsøe, Henrik; Jakobsen, Hans J; Skibsted, Jørgen

2012-08-01

A new version of the double cross-polarization MAS NMR experiment, which transfers polarization Forth and Back (FBCP) between high- and low-γ spin nuclei, is presented. The pulse sequence is demonstrated by ¹⁹F-{²⁹Si}-¹⁹F and ¹⁹F-{¹³C}-¹⁹F FBCP NMR spectra of a mixture of cuspidine (Ca₄Si₂O₇F₂) and Teflon (-CF₂-)(n). The experiment is useful for assignment of the high-γ spin resonances, as demonstrated by ¹⁹F-{²⁹Si}-¹⁹F FBCP NMR of a fluoride-containing calcium-silicate-hydrate (C-S-H) phase, where the ¹⁹F resonance from fluoride ions incorporated in the interlayer structure of the C-S-H phase is identified. Copyright © 2012 Elsevier Inc. All rights reserved.

Carbon-deuterium rotational-echo double-resonance NMR spectroscopy of lyophilized aspartame formulations.

PubMed

Luthra, Suman A; Utz, Marcel; Gorman, Eric M; Pikal, Michael J; Munson, Eric J; Lubach, Joseph W

2012-01-01

In this study, changes in the local conformation of aspartame were observed in annealed lyophilized glasses by monitoring changes in the distance between two labeled sites using C-(2)H rotational-echo double-resonance (REDOR) nuclear magnetic resonance (NMR) spectroscopy. Confirmation that the REDOR experiments were producing accurate distance measurement was ensured by measuring the (13)C-(15)N distance in glycine. The experiment was further verified by measuring the REDOR dephasing curve on (13)C-(2)H methionine. (13)C-(2)H REDOR dephasing curves were then measured on lyophilized aspartame-disaccharide formulations. In aspartame-sucrose formulation, the internuclear distances increased upon annealing, which correlated with decreased chemical reactivity. By contrast, annealing had only a minimal effect on the dephasing curve in aspartame-trehalose formulation. The results show that stability is a function of both mobility and local structure (conformation), even in a small molecule system such as lyophilized aspartame-sucrose. Copyright © 2011 Wiley-Liss, Inc.

Harmonic Generation in InAs Nanowire Double Quantum Dots

NASA Astrophysics Data System (ADS)

Schroer, M. D.; Jung, M.; Petersson, K. D.; Petta, J. R.

2012-02-01

InAs nanowires provide a useful platform for investigating the physics of confined electrons subjected to strong spin-orbit coupling. Using tunable, bottom-gated double quantum dots, we demonstrate electrical driving of single spin resonance.ootnotetextS. Nadj-Perge et al., Nature 468, 1084 (2010)^,ootnotetextM.D. Schroer et al., Phys. Rev. Lett. 107, 176811 (2011) We observe a standard spin response when the applied microwave frequency equals the Larmour frequency f0. However, we also observe an anomalous signal at frequencies fn= f0/ n for integer n up to n ˜5. This is equivalent to generation of harmonics of the spin resonance field. While a f0/2 signal has observed,ootnotetextE.A. Laird et al., Phys. Rev. Lett. 99, 246601 (2007) we believe this is the first observation of higher harmonics in spin resonance. Possible mechanisms will be discussed.ootnotetextE.I. Rashba, arXiv:1110.6569 (2011) Acknowledgements: Research supported by the Sloan and Packard Foundations, the NSF, and Army Research Office.

Low losses left-handed materials with optimized electric and magnetic resonance

NASA Astrophysics Data System (ADS)

Zhou, Xin; Liu, Yahong; Zhao, Xiaopeng

2010-03-01

We propose that the losses in left-handed materials (LHMs) can be significantly affected by changing the coupling relationship between electric and magnetic resonance. A double bowknot shaped structure (DBS) is used to construct the LHMs. And the magnetic resonance of the DBS, which resonated in the case of lower and higher frequencies than the electric resonant dip, is studied in simulation and experiment by tailoring the structural parameters. The case of magnetic resonance located at low electric resonance frequencies band is confirmed to have relatively low losses. Using full wave simulation of prism shaped structure composed of DBS unit cells, we prove the negative refraction behavior in such a frame. This study can serve as a guide for designing other similar metal-dielectric-metal (MDM) in low losses at terahertz or higher frequencies.

Sealed magic angle spinning nuclear magnetic resonance probe and process for spectroscopy of hazardous samples

DOEpatents

Cho, Herman M.; Washton, Nancy M.; Mueller, Karl T.; Sears, Jr., Jesse A.; Townsend, Mark R.; Ewing, James R.

2016-06-14

A magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) probe is described that includes double containment enclosures configured to seal and contain hazardous samples for analysis. The probe is of a modular design that ensures containment of hazardous samples during sample analysis while preserving spin speeds for superior NMR performance and convenience of operation.

Cross section of resonant Raman scattering of light by polyenes

NASA Astrophysics Data System (ADS)

Verdyugin, V. V.; Burshteyn, K. Ya.; Shorygin, P. P.

1987-03-01

An experimental study is presented of the resonant Raman spectra of beta carotene. Absolute differential cross sections are obtained for the most intensive Raman spectral lines with excitation at the absorption maximum. A theoretical analysis is presented of the variation in absolute differential cross section as a function of a number of conjunct double bonds in the polyenes.

Detection of cerebral amyloid angiopathy by 3-T magnetic resonance imaging and amyloid positron emission tomography in a patient with subcortical ischaemic vascular dementia.

PubMed

Kida, Hirotaka; Satoh, Masayuki; Ii, Yuichiro; Fukuyama, Hidenao; Maeda, Masayuki; Tomimoto, Hidekazu

2017-01-01

The patient was an 81-year-old man who had been treated for hypertension for several decades. In 2012, he developed gait disturbance and mild amnesia. One year later, his gait disturbance worsened, and he developed urinary incontinence. Conventional brain magnetic resonance imaging using T 2 -weighted images and fluid-attenuated inversion recovery showed multiple lacunar infarctions. These findings fulfilled the diagnostic criteria for subcortical ischaemic vascular dementia. However, susceptibility weighted imaging showed multiple lobar microbleeds in the bilateral occipitoparietal lobes, and double inversion recovery and 3-D fluid-attenuated inversion recovery images on 3-T magnetic resonance imaging revealed cortical microinfarctions in the left parietal-temporo-occipito region. Pittsburgh compound B-positron emission tomography revealed diffuse uptake in the cerebral cortex. Therefore, we diagnosed the patient with subcortical ischaemic vascular dementia associated with Alzheimer's disease. The use of the double inversion recovery and susceptibility weighted imaging on 3-T magnetic resonance imaging may be a supplemental strategy for diagnosing cerebral amyloid angiopathy, which is closely associated with Alzheimer's disease. © 2016 The Authors. Psychogeriatrics © 2016 Japanese Psychogeriatric Society.

Determination of the Stoichiometry between α- and γ1 Subunits of the BK Channel Using LRET.

PubMed

Carrasquel-Ursulaez, Willy; Alvarez, Osvaldo; Bezanilla, Francisco; Latorre, Ramon

2018-06-05

Two families of accessory proteins, β and γ, modulate BK channel gating and pharmacology. Notably, in the absence of internal Ca 2+ , the γ1 subunit promotes a large shift of the BK conductance-voltage curve to more negative potentials. However, very little is known about how α- and γ1 subunits interact. In particular, the association stoichiometry between both subunits is unknown. Here, we propose a method to answer this question using lanthanide resonance energy transfer. The method assumes that the kinetics of lanthanide resonance energy transfer-sensitized emission of the donor double-labeled α/γ1 complex is the linear combination of the kinetics of the sensitized emission in single-labeled complexes. We used a lanthanide binding tag engineered either into the α- or the γ1 subunits to bind Tb +3 as the donor. The acceptor (BODIPY) was attached to the BK pore-blocker iberiotoxin. We determined that γ1 associates with the α-subunit with a maximal 1:1 stoichiometry. This method could be applied to determine the stoichiometry of association between proteins within heteromultimeric complexes. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

On-chip broadband spectral filtering using planar double high-contrast grating reflectors

NASA Astrophysics Data System (ADS)

Horie, Yu; Arbabi, Amir; Faraon, Andrei

2015-02-01

We propose a broadband free-space on-chip spectrometer based on an array of integrated narrowband filters consisting of Fabry-Perot resonators formed by two high-contrast grating (HCG) based reflectors separated by a low-index thin layer with a fixed cavity thickness. Using numerical simulations, broadband tunability of resonance wavelengths was achieved only by changing the in-plane grating parameters such as period or duty cycle of HCGs while the substrate geometry was kept fixed. Experimentally, the HCG reflectors were fabricated on silicon on insulator (SOI) substrates and high reflectivity was measured, fabrication process for the proposed double HCG-based narrowband filter array was developed. The filtering function that can be spanned over a wide range of wavelengths was measured.

Opal-based photonic crystal with double photonic bandgap structure

NASA Astrophysics Data System (ADS)

Romanov, S. G.; Yates, H. M.; Pemble, M. E.; DeLa Rue, R. M.

2000-09-01

The interior surfaces of one part of a piece of artificial opal have been coated with GaP so that the remaining part of the opal crystal remains empty, thus forming a photonic heterostructure. Two Bragg resonances have been observed in the optical transmission and reflectance spectra. These two resonances were found to behave differently with changes in the polarization of the incident light and the angle of propagation of the light with respect to the (111) planes of opal. Depolarization of the light was observed to occur most effectively at frequencies within the stop-bands, apparently due to the re-coupling of the propagating electromagnetic wave to a different system of eigenmodes when it crosses the interface separating two parts of the double photonic crystal.

Resonant tunneling spectroscopy of valley eigenstates on a donor-quantum dot coupled system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kobayashi, T., E-mail: t.kobayashi@unsw.edu.au; Heijden, J. van der; House, M. G.

We report on electronic transport measurements through a silicon double quantum dot consisting of a donor and a quantum dot. Transport spectra show resonant tunneling peaks involving different valley states, which illustrate the valley splitting in a quantum dot on a Si/SiO{sub 2} interface. The detailed gate bias dependence of double dot transport allows a first direct observation of the valley splitting in the quantum dot, which is controllable between 160 and 240 μeV with an electric field dependence 1.2 ± 0.2 meV/(MV/m). A large valley splitting is an essential requirement for implementing a physical electron spin qubit in a silicon quantum dot.

Determination of molecular spectroscopic parameters and energy-transfer rates by double-resonance spectroscopy

NASA Technical Reports Server (NTRS)

Steinfeld, J. I.; Foy, B.; Hetzler, J.; Flannery, C.; Klaassen, J.; Mizugai, Y.; Coy, S.

1990-01-01

The spectroscopy of small to medium-size polyatomic molecules can be extremely complex, especially in higher-lying overtone and combination vibrational levels. The high density of levels also complicates the understanding of inelastic collision processes, which is required to model energy transfer and collision broadening of spectral lines. Both of these problems can be addressed by double-resonance spectroscopy, i.e., time-resolved pump-probe measurements using microwave, infrared, near-infrared, and visible-wavelength sources. Information on excited-state spectroscopy, transition moments, inelastic energy transfer rates and propensity rules, and pressure-broadening parameters may be obtained from such experiments. Examples are given for several species of importance in planetary atmospheres, including ozone, silane, ethane, and ammonia.

Improved convection compensating pulsed field gradient spin-echo and stimulated-echo methods.

PubMed

Sørland, G H; Seland, J G; Krane, J; Anthonsen, H W

2000-02-01

The need for convection compensating methods in NMR has been manifested through an increasing number of publications related to the subject over the past few years (J. Magn. Reson. 125, 372 (1997); 132, 13 (1998); 131, 126 (1998); 118, 50 (1996); 133, 379 (1998)). When performing measurements at elevated temperature, small convection currents may give rise to erroneous values of the diffusion coefficient. In work with high resolution NMR spectroscopy, the application of magnetic field gradients also introduces an eddy-current magnetic field which may result in errors in phase and baseline in the FFT-spectra. The eddy current field has been greatly suppressed by the application of bipolar magnetic field gradients. However, when introducing bipolar magnetic field gradients, the pulse sequence is lengthened significantly. This has recently been pointed out as a major drawback because of the loss of coherence and of NMR-signal due to transverse relaxation processes. Here we present modified convection compensating pulsed field gradient double spin echo and double stimulated echo sequences which suppress the eddy-current magnetic field without increasing the duration of the pulse sequences. Copyright 2000 Academic Press.

Investigation of a driven fermionic system and detecting chiral edge modes in an optical lattice

NASA Astrophysics Data System (ADS)

Görg, Frederik; Messer, Michael; Jotzu, Gregor; Sandholzer, Kilian; Desbuquois, Rémi; Goldman, Nathan; Esslinger, Tilman

2017-04-01

Periodically driven systems of ultracold fermions in optical lattices allow to implement a large variety of effective Hamiltonians through Floquet engineering. An important question is whether this method can be extended to interacting systems. We investigate driven two-body systems in an array of double wells and measure the double occupancy and the spin-spin correlator in the large frequency limit and when driving resonantly to an energy scale of the underlying static Hamiltonian. We analyze whether the emerging states of the driven system can be adiabatically connected to states in the unshaken lattice. In addition, we measure the amplitude of the micromotion which describes the short time dynamics of the system and compare it directly to theory. In another context we propose a method to create topological interfaces and detect chiral edge modes in a two dimensional optical lattice. We illustrate this through an optical lattice realization of the Haldane model for cold atoms, where an additional spatially-varying lattice potential induces distinct topological phases in separated regions of space.

Accurate computer-aided quantification of left ventricular parameters: experience in 1555 cardiac magnetic resonance studies from the Framingham Heart Study.

PubMed

Hautvast, Gilion L T F; Salton, Carol J; Chuang, Michael L; Breeuwer, Marcel; O'Donnell, Christopher J; Manning, Warren J

2012-05-01

Quantitative analysis of short-axis functional cardiac magnetic resonance images can be performed using automatic contour detection methods. The resulting myocardial contours must be reviewed and possibly corrected, which can be time-consuming, particularly when performed across all cardiac phases. We quantified the impact of manual contour corrections on both analysis time and quantitative measurements obtained from left ventricular short-axis cine images acquired from 1555 participants of the Framingham Heart Study Offspring cohort using computer-aided contour detection methods. The total analysis time for a single case was 7.6 ± 1.7 min for an average of 221 ± 36 myocardial contours per participant. This included 4.8 ± 1.6 min for manual contour correction of 2% of all automatically detected endocardial contours and 8% of all automatically detected epicardial contours. However, the impact of these corrections on global left ventricular parameters was limited, introducing differences of 0.4 ± 4.1 mL for end-diastolic volume, -0.3 ± 2.9 mL for end-systolic volume, 0.7 ± 3.1 mL for stroke volume, and 0.3 ± 1.8% for ejection fraction. We conclude that left ventricular functional parameters can be obtained under 5 min from short-axis functional cardiac magnetic resonance images using automatic contour detection methods. Manual correction more than doubles analysis time, with minimal impact on left ventricular volumes and ejection fraction. Copyright © 2011 Wiley Periodicals, Inc.

Detection of DNA Sequences Refractory to PCR Amplification Using a Biophysical SERRS Assay (Surface Enhanced Resonant Raman Spectroscopy)

PubMed Central

Feuillie, Cécile; Merheb, Maxime M.; Gillet, Benjamin; Montagnac, Gilles; Daniel, Isabelle; Hänni, Catherine

2014-01-01

The analysis of ancient or processed DNA samples is often a great challenge, because traditional Polymerase Chain Reaction – based amplification is impeded by DNA damage. Blocking lesions such as abasic sites are known to block the bypass of DNA polymerases, thus stopping primer elongation. In the present work, we applied the SERRS-hybridization assay, a fully non-enzymatic method, to the detection of DNA refractory to PCR amplification. This method combines specific hybridization with detection by Surface Enhanced Resonant Raman Scattering (SERRS). It allows the detection of a series of double-stranded DNA molecules containing a varying number of abasic sites on both strands, when PCR failed to detect the most degraded sequences. Our SERRS approach can quickly detect DNA molecules without any need for DNA repair. This assay could be applied as a pre-requisite analysis prior to enzymatic reparation or amplification. A whole new set of samples, both forensic and archaeological, could then deliver information that was not yet available due to a high degree of DNA damage. PMID:25502338

Detection of DNA sequences refractory to PCR amplification using a biophysical SERRS assay (Surface Enhanced Resonant Raman Spectroscopy).

PubMed

Feuillie, Cécile; Merheb, Maxime M; Gillet, Benjamin; Montagnac, Gilles; Daniel, Isabelle; Hänni, Catherine

2014-01-01

The analysis of ancient or processed DNA samples is often a great challenge, because traditional Polymerase Chain Reaction - based amplification is impeded by DNA damage. Blocking lesions such as abasic sites are known to block the bypass of DNA polymerases, thus stopping primer elongation. In the present work, we applied the SERRS-hybridization assay, a fully non-enzymatic method, to the detection of DNA refractory to PCR amplification. This method combines specific hybridization with detection by Surface Enhanced Resonant Raman Scattering (SERRS). It allows the detection of a series of double-stranded DNA molecules containing a varying number of abasic sites on both strands, when PCR failed to detect the most degraded sequences. Our SERRS approach can quickly detect DNA molecules without any need for DNA repair. This assay could be applied as a pre-requisite analysis prior to enzymatic reparation or amplification. A whole new set of samples, both forensic and archaeological, could then deliver information that was not yet available due to a high degree of DNA damage.

Dynamic characterization of small fibers based on the flexural vibrations of a piezoelectric cantilever probe

NASA Astrophysics Data System (ADS)

Zhang, Xiaofei; Ye, Xuan; Li, Xide

2016-08-01

In this paper, we present a cantilever-probe system excited by a piezoelectric actuator, and use it to measure the dynamic mechanical properties of a micro- and nanoscale fiber. Coupling the fiber to the free end of the cantilever probe, we found the dynamic stiffness and damping coefficient of the fiber from the resonance frequency and the quality factor of the fiber-cantilever-probe system. The properties of Bacillus subtilis fibers measured using our proposed system agreed with tensile measurements, validating our method. Our measurements show that the piezoelectric actuator coupled to cantilever probe can be made equivalent to a clamped cantilever with an effective length, and calculated results show that the errors of measured natural frequency of the system can be ignored if the coupled fiber has an inclination angle of alignment of less than 10°. A sensitivity analysis indicates that the first or second resonant mode is the sensitive mode to test the sample’s dynamic stiffness, while the damping property has different sensitivities for the first four modes. Our theoretical analysis demonstrates that the double-cantilever probe is also an effective sensitive structure that can be used to perform dynamic loading and characterize dynamic response. Our method has the advantage of using amplitude-frequency curves to obtain the dynamic mechanical properties without directly measuring displacements and forces as in tensile tests, and it also avoids the effects of the complex surface structure and deformation presenting in contact resonance method. Our method is effective for measuring the dynamic mechanical properties of fiber-like one-dimensional (1D) materials.

Optimally designed narrowband guided-mode resonance reflectance filters for mid-infrared spectroscopy

PubMed Central

Liu, Jui-Nung; Schulmerich, Matthew V.; Bhargava, Rohit; Cunningham, Brian T.

2011-01-01

An alternative to the well-established Fourier transform infrared (FT-IR) spectrometry, termed discrete frequency infrared (DFIR) spectrometry, has recently been proposed. This approach uses narrowband mid-infrared reflectance filters based on guided-mode resonance (GMR) in waveguide gratings, but filters designed and fabricated have not attained the spectral selectivity (≤ 32 cm−1) commonly employed for measurements of condensed matter using FT-IR spectroscopy. With the incorporation of dispersion and optical absorption of materials, we present here optimal design of double-layer surface-relief silicon nitride-based GMR filters in the mid-IR for various narrow bandwidths below 32 cm−1. Both shift of the filter resonance wavelengths arising from the dispersion effect and reduction of peak reflection efficiency and electric field enhancement due to the absorption effect show that the optical characteristics of materials must be taken into consideration rigorously for accurate design of narrowband GMR filters. By incorporating considerations for background reflections, the optimally designed GMR filters can have bandwidth narrower than the designed filter by the antireflection equivalence method based on the same index modulation magnitude, without sacrificing low sideband reflections near resonance. The reported work will enable use of GMR filters-based instrumentation for common measurements of condensed matter, including tissues and polymer samples. PMID:22109445

Electrically Driving Donor Spin Qubits in Silicon Using Photonic Bandgap Resonators

NASA Astrophysics Data System (ADS)

Sigillito, A. J.; Tyryshkin, A. M.; Lyon, S. A.

In conventional experiments, donor nuclear spin qubits in silicon are driven using radiofrequency (RF) magnetic fields. However, magnetic fields are difficult to confine at the nanoscale, which poses major issues for individually addressable qubits and device scalability. Ideally one could drive spin qubits using RF electric fields, which are easy to confine, but spins do not naturally have electric dipole transitions. In this talk, we present a new method for electrically controlling nuclear spin qubits in silicon by modulating the hyperfine interaction between the nuclear spin qubit and the donor-bound electron. By fabricating planar superconducting photonic bandgap resonators, we are able to use pulsed electron-nuclear double resonance (ENDOR) techniques to selectively probe both electrically and magnetically driven transitions for 31P and 75As nuclear spin qubits. The electrically driven spin resonance mechanism allows qubits to be driven at either their transition frequency, or at one-half their transition frequency, thus reducing bandwidth requirements for future quantum devices. Moreover, this form of control allows for higher qubit densities and lower power requirements compared to magnetically driven schemes. In our proof-of-principle experiments we demonstrate electrically driven Rabi frequencies of approximately 50 kHz for widely spaced (10 μm) gates which should be extendable to MHz for nanoscale devices.

Mechanisms for the Dissipation of Alfven Waves in Near-Earth Space Plasma

NASA Technical Reports Server (NTRS)

Singh, Nagendra; Khazanov, George; Krivorutsky, E. N.; Davis, John M. (Technical Monitor)

2002-01-01

Alfven waves are a major mechanism for the transport of electromagnetic energy from the distant part of the magnetosphere to the near-Earth space. This is especially true for the auroral and polar regions of the Earth. However, the mechanisms for their dissipation have remained illusive. One of the mechanisms is the formation of double layers when the current associated with Alfven waves in the inertial regime interact with density cavities, which either are generated nonlinearly by the waves themselves or are a part of the ambient plasma turbulence. Depending on the strength of the cavities, weak and strong double layers could form. Such double layers are transient; their lifetimes depend on that of the cavities. Thus they impulsively accelerate ions and electrons. Another mechanism is the resonant absorption of broadband Alfven- wave noise by the ions at the ion cyclotron frequencies. But this resonant absorption may not be possible for the very low frequency waves, and it may be more suited for electromagnetic ion cyclotron waves. A third mechanism is the excitation of secondary waves by the drifts of electrons and ions in the Alfven wave fields. It is found that under suitable conditions, the relative drifts between different ion species and/or between electrons and ions are large enough to drive lower hybrid waves, which could cause transverse accelerations of ions and parallel accelerations of electrons. This mechanism is being further studied by means of kinetic simulations using 2.5- and 3-D particle-in-cell codes. The ongoing modeling efforts on space weather require quantitative estimates of energy inputs of various kinds, including the electromagnetic energy. Our studies described here contribute to the methods of determining the estimates of the input from ubiquitous Alfven waves.

Tidal distortion caused by the resonance of sexta-diurnal tides in a micromesotidal embayment

NASA Astrophysics Data System (ADS)

Song, Dehai; Yan, Yuhan; Wu, Wen; Diao, Xiliang; Ding, Yang; Bao, Xianwen

2016-10-01

Double high water and double-peak flood current were observed in Daya Bay (DYB), China, which is a shallow, mixed, mainly semidiurnal-tide dominated bay with a micro to mesotidal range. Harmonic analysis reveals that the quarter and especially the sexta-diurnal constituents are getting much stronger as tides propagating into the bay. The astronomical tides-induced tidal asymmetry is yet dominant at the bay entrance but overtaken by the sexta-diurnal tides at the end of the bay. Both the M4 and M6 tide meet the requirement proposed in previous studies but still unable to produce a double high water alone. Therefore, the conditions to produce a double high water between a fundamental tide and its higher harmonics need to be revisited. Analytical solutions were obtained in this paper, which fit the numerical solutions very well. Modeling result indicates M6 alone with M2 can produce the double high water in DYB but limited in some regions, while the combination of M2, M4, and M6 tides would enhance the capability. The amplification of sexta-diurnal tides in DYB is dominated by resonance and followed by shoaling effect. Bottom friction damped M6 a lot and largely confined its amplification. However, the quadratic friction and other nonlinear processes are just responsible for about 10% of the total M6 increase.

Coherent wave packet dynamics in a double-well potential in cavity

NASA Astrophysics Data System (ADS)

Zheng, Li; Li, Gang; Ding, Ming-Song; Wang, Yong-Liang; Zhang, Yun-Cui

2018-02-01

We investigate the coherent wave packet dynamics of a two-level atom trapped in a symmetric double-well potential in a near-resonance cavity. Prepared on one side of the double-well potential, the atom wave packet oscillates between the left and right wells, while recoil induced by the emitted photon from the atom entangles the atomic internal and external degrees of freedom. The collapse and revival of the tunneling occurs. Adjusting the width of the wave packets, one can modify the tunneling frequency and suppress the tunneling.

Density-matrix renormalization group method for the conductance of one-dimensional correlated systems using the Kubo formula

NASA Astrophysics Data System (ADS)

Bischoff, Jan-Moritz; Jeckelmann, Eric

2017-11-01

We improve the density-matrix renormalization group (DMRG) evaluation of the Kubo formula for the zero-temperature linear conductance of one-dimensional correlated systems. The dynamical DMRG is used to compute the linear response of a finite system to an applied ac source-drain voltage; then the low-frequency finite-system response is extrapolated to the thermodynamic limit to obtain the dc conductance of an infinite system. The method is demonstrated on the one-dimensional spinless fermion model at half filling. Our method is able to replicate several predictions of the Luttinger liquid theory such as the renormalization of the conductance in a homogeneous conductor, the universal effects of a single barrier, and the resonant tunneling through a double barrier.

Control of fluorescence in quantum emitter and metallic nanoshell hybrids for medical applications

NASA Astrophysics Data System (ADS)

Singh, Mahi R.; Guo, Jiaohan; J. Cid, José M.; De Hoyos Martinez, Jesús E.

2017-03-01

We study the light emission from a quantum emitter and double metallic nanoshell hybrid systems. Quantum emitters act as local sources which transmit their light efficiently due to a double nanoshell near field. The double nanoshell consists of a dielectric core and two outer nanoshells. The first nanoshell is made of a metal, and the second spacer nanoshell is made of a dielectric material or human serum albumin. We have calculated the fluorescence emission for a quantum emitter-double nanoshell hybrid when it is injected in an animal or a human body. Surface plasmon polariton resonances in the double nanoshell are calculated using Maxwell's equations in the quasi-static approximation, and the fluorescence emission is evaluated using the density matrix method in the presence of dipole-dipole interactions. We have compared our theory with two fluorescence experiments in hybrid systems in which the quantum emitter is Indocyanine Green or infrared fluorescent molecules. The outer spacer nanoshell of double metallic nanoshells consists of silica and human serum albumin with variable thicknesses. Our theory explains the enhancement of fluorescence spectra in both experiments. We find that the thickness of the spacer nanoshell layer increases the enhancement when the fluorescence decreases. The enhancement of the fluorescence depends on the type of quantum emitter, spacer layer, and double nanoshell. We also found that the peak of the fluorescence spectrum can be shifted by changing the shape and the size of the nanoshell. The fluorescence spectra can be switched from one peak to two peaks by removing the degeneracy of excitonic states in the quantum emitter. Hence, using these properties, one can use these hybrids as sensing and switching devices for applications in medicine.

The Double-Weave of Self and Other: Ethnographic Acts and Autobiographical Occasions in Marilou Awiakta's "Selu: Seeking the Corn-Mother's Wisdom"

ERIC Educational Resources Information Center

Watkins, James H.

2006-01-01

In the opening pages of Marilou Awiakta's "Selu: Seeking the Corn-Mother's Wisdom," the author offers a metacommentary on her delightfully hybrid text, likening it to a "double-woven basket (Cherokee-style)." The image resonates on many levels with the author's tribal traditions and thus serves to foreshadow the text's wealth of material on…

Chemical exchange rotation transfer (CERT) on human brain at 3 Tesla.

PubMed

Lin, Eugene C; Li, Hua; Zu, Zhongliang; Louie, Elizabeth A; Lankford, Christopher L; Dortch, Richard D; Does, Mark D; Gore, John C; Gochberg, Daniel F

2018-05-25

To test the ability of a novel pulse sequence applied in vivo at 3 Tesla to separate the contributions to the water signal from amide proton transfer (APT) and relayed nuclear Overhauser enhancement (rNOE) from background direct water saturation and semisolid magnetization transfer (MT). The lack of such signal source isolation has confounded conventional chemical exchange saturation transfer (CEST) imaging. We quantified APT and rNOE signals using a chemical exchange rotation transfer (CERT) metric, MTR double . A range of duty cycles and average irradiation powers were applied, and results were compared with conventional CEST analyses using asymmetry (MTR asym ) and extrapolated magnetization transfer (EMR). Our results indicate that MTR double is more specific than MTR asym and, because it requires as few as 3 data points, is more rapid than methods requiring a complete Z-spectrum, such as EMR. In white matter, APT (1.5 ± 0.5%) and rNOE (2.1 ± 0.7%) were quantified by using MTR double with a 30% duty cycle and a 0.5-µT average power. In addition, our results suggest that MTR double is insensitive to B 0 inhomogeneity, further magnifying its speed advantage over CEST metrics that require a separate B 0 measurement. However, MTR double still has nontrivial sensitivity to B 1 inhomogeneities. We demonstrated that MTR double is an alternative metric to evaluate APT and rNOE, which is fast, robust to B 0 inhomogeneity, and easy to process. © 2018 International Society for Magnetic Resonance in Medicine.

Enhanced spin-torque in double tunnel junctions using a nonmagnetic-metal spacer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, C. H.; Cheng, Y. H.; Ko, C. W.

2015-10-12

This study proposes an enhancement in the spin-transfer torque of a magnetic tunnel junction (MTJ) designed with double-barrier layer structure using a nonmagnetic metal spacer, as a replacement for the ferromagnetic material, which is traditionally used in these double-barrier stacks. Our calculation results show that the spin-transfer torque and charge current density of the proposed double-barrier MTJ can be as much as two orders of magnitude larger than the traditional double-barrier one. In other words, the proposed double-barrier MTJ has a spin-transfer torque that is three orders larger than that of the single-barrier stack. This improvement may be attributed tomore » the quantum-well states that are formed in the nonmagnetic metal spacer and the resonant tunneling mechanism that exists throughout the system.« less

A 2D spiral turbo-spin-echo technique.

PubMed

Li, Zhiqiang; Karis, John P; Pipe, James G

2018-03-09

2D turbo-spin-echo (TSE) is widely used in the clinic for neuroimaging. However, the long refocusing radiofrequency pulse train leads to high specific absorption rate (SAR) and alters the contrast compared to conventional spin-echo. The purpose of this work is to develop a robust 2D spiral TSE technique for fast T 2 -weighted imaging with low SAR and improved contrast. A spiral-in/out readout is incorporated into 2D TSE to fully take advantage of the acquisition efficiency of spiral sampling while avoiding potential off-resonance-related artifacts compared to a typical spiral-out readout. A double encoding strategy and a signal demodulation method are proposed to mitigate the artifacts because of the T 2 -decay-induced signal variation. An adapted prescan phase correction as well as a concomitant phase compensation technique are implemented to minimize the phase errors. Phantom data demonstrate the efficacy of the proposed double encoding/signal demodulation, as well as the prescan phase correction and concomitant phase compensation. Volunteer data show that the proposed 2D spiral TSE achieves fast scan speed with high SNR, low SAR, and improved contrast compared to conventional Cartesian TSE. A robust 2D spiral TSE technique is feasible and provides a potential alternative to conventional 2D Cartesian TSE for T 2 -weighted neuroimaging. © 2018 International Society for Magnetic Resonance in Medicine.

In vivo Proton Electron Double Resonance Imaging of Mice with Fast Spin Echo Pulse Sequence

PubMed Central

Sun, Ziqi; Li, Haihong; Petryakov, Sergey; Samouilov, Alex; Zweier, Jay L.

2011-01-01

Purpose To develop and evaluate a 2D fast spin echo (FSE) pulse sequence for enhancing temporal resolution and reducing tissue heating for in vivo proton electron double resonance imaging (PEDRI) of mice. Materials and Methods A four-compartment phantom containing 2 mM TEMPONE was imaged at 20.1 mT using 2D FSE-PEDRI and regular gradient echo (GRE)-PEDRI pulse sequences. Control mice were infused with TEMPONE over ∼1 min followed by time-course imaging using the 2D FSE-PEDRI sequence at intervals of 10 – 30 s between image acquisitions. The average signal intensity from the time-course images was analyzed using a first-order kinetics model. Results Phantom experiments demonstrated that EPR power deposition can be greatly reduced using the FSE-PEDRI pulse sequence compared to the conventional gradient echo pulse sequence. High temporal resolution was achieved at ∼4 s per image acquisition using the FSE-PEDRI sequence with a good image SNR in the range of 233-266 in the phantom study. The TEMPONE half-life measured in vivo was ∼72 s. Conclusion Thus, the FSE-PEDRI pulse sequence enables fast in vivo functional imaging of free radical probes in small animals greatly reducing EPR irradiation time with decreased power deposition and provides increased temporal resolution. PMID:22147559

Monolithic integration of a resonant tunneling diode and a quantum well semiconductor laser

NASA Astrophysics Data System (ADS)

Grave, I.; Kan, S. C.; Griffel, G.; Wu, S. W.; Sa'Ar, A.

1991-01-01

A monolithic integration of a double barrier AlAs/GaAs resonant tunneling diode and a GaAs/AlGaAs quantum well laser is reported. Negative differential resistance and negative differential optical response are observed at room temperature. The device displays bistable electrical and optical characteristics which are voltage controlled. Operation as a two-state optical memory is demonstrated.

Multiturn split-conductor transmission-line resonator

NASA Astrophysics Data System (ADS)

Haziza, Nathalie; Bittoun, Jacques; Kan, Siew

1997-05-01

A split-conductor parallel-plate transmission line resonator is a simple structure made from bending a strip of double-face copper-clad printed-circuit board into a loop with alternate electrical discontinuities (gaps) on opposite sides. Its natural resonant frequency (Fn) is determined by the transmission line characteristic impedance, the loop diameter or strip length, and the number (Ng) of gaps. It is easy to design high frequency resonators simply by increasing Ng. We propose here a single-gap multiturn resonator for low frequency operation as well as a simplified expression for the determination of Fn. A design procedure of this type of resonator is outlined and illustrative examples with parallel-plate as well as ordinary 50 Ω coaxial transmission lines are given. Also, for a given cable length, numerical calculation shows that the minimum resonator frequency can be attained with a form factor of the order of 2.

Demodulation method for tilted fiber Bragg grating refractometer with high sensitivity

NASA Astrophysics Data System (ADS)

Pham, Xuantung; Si, Jinhai; Chen, Tao; Wang, Ruize; Yan, Lihe; Cao, Houjun; Hou, Xun

2018-05-01

In this paper, we propose a demodulation method for refractive index (RI) sensing with tilted fiber Bragg gratings (TFBGs). It operates by monitoring the TFBG cladding mode resonance "cut-off wavelengths." The idea of a "cut-off wavelength" and its determination method are introduced. The RI sensitivities of TFBGs are significantly enhanced in certain RI ranges by using our demodulation method. The temperature-induced cross sensitivity is eliminated. We also demonstrate a parallel-double-angle TFBG (PDTFBG), in which two individual TFBGs are inscribed in the fiber core in parallel using a femtosecond laser and a phase mask. The RI sensing range of the PDTFBG is significantly broader than that of a conventional single-angle TFBG. In addition, its RI sensitivity can reach 1023.1 nm/refractive index unit in the 1.4401-1.4570 RI range when our proposed demodulation method is used.

Entropic stochastic resonance of a self-propelled Janus particle

NASA Astrophysics Data System (ADS)

Liu, Zhenzhen; Du, Luchun; Guo, Wei; Mei, Dong-Cheng

2016-10-01

Entropic stochastic resonance is investigated when a self-propelled Janus particle moves in a double-cavity container. Numerical simulation results indicate the entropic stochastic resonance can survive even if there is no symmetry breaking in any direction. This is the essential distinction between the property of a self-propelled Janus particle and that of a passive Brownian particle, for the symmetry breaking is necessary for the entropic stochastic resonance of a passive Brownian particle. With the rotational noise intensity growing at small fixed noise intensity of translational motion, the signal power amplification increases monotonically towards saturation which also can be regarded as a kind of stochastic resonance effect. Besides, the increase in the natural frequency of the periodic driving depresses the degree of the stochastic resonance, whereas the rise in its amplitude enhances and then suppresses the behavior.

Double-quantum homonuclear correlations of spin I=5/2 nuclei.

PubMed

Iuga, Dinu

2011-02-01

The challenges associated with acquiring double-quantum homonuclear Nuclear Magnetic Resonance correlation spectra of half-integer quadrupolar nuclei are described. In these experiments the radio-frequency irradiation amplitude is necessarily weak in order to selectively excite the central transition. In this limit only one out of the 25 double-quantum coherences possible for two coupled spin I=5/2 nuclei is excited. An investigation of all the 25 two spins double quantum transitions reveals interesting effects such as a compensation of the first-order quadrupolar interaction between the two single quantum transitions involved in the double quantum coherence. In this paper a full numerical study of a hypothetical two spin I=5/2 system is used to show what happens when the RF amplitude during recoupling is increased. In principle this is advantageous, since the required double quantum coherence should build up faster, but in practice it also induces adiabatic passage transfer of population and coherence which impedes any build up. Finally an optimized rotary resonance recoupling (oR(3)) sequence is introduced in order to decrease these transfers. This sequence consists of a spin locking irradiation whose amplitude is reduced four times during one rotor period, and allows higher RF powers to be used during recoupling. The sequence is used to measure (27)Al DQ dipolar correlation spectra of Y(3)Al(5)O(12) (YAG) and gamma alumina (γAl(2)O(3)). The results prove that aluminium vacancies in gamma alumina mainly occur in the tetrahedral sites. Copyright © 2010 Elsevier Inc. All rights reserved.

Numerical Comparison of Active Acoustic and Structural Noise Control in a Stiffened Double Wall Cylinder

NASA Technical Reports Server (NTRS)

Grosveld, Ferdinand W.

1996-01-01

The active acoustic and structural noise control characteristics of a double wall cylinder with and without ring stiffeners were numerically evaluated. An exterior monopole was assumed to acoustically excite the outside of the double wall cylinder at an acoustic cavity resonance frequency. Structural modal vibration properties of the inner and outer shells were analyzed by post-processing the results from a finite element analysis. A boundary element approach was used to calculate the acoustic cavity response and the coupled structural-acoustic interaction. In the frequency region of interest, below 500 Hz, all structural resonant modes were found to be acoustically slow and the nonresonant modal response to be dominant. Active sound transmission control was achieved by control forces applied to the inner or outer shell, or acoustic control monopoles placed just outside the inner or outer shell. A least mean square technique was used to minimize the interior sound pressures at the nodes of a data recovery mesh. Results showed that single acoustic control monopoles placed just outside the inner or outer shells resulted in better sound transmission control than six distributed point forces applied to either one of the shells. Adding stiffeners to the double wall structure constrained the modal vibrations of the shells, making the double wall stiffer with associated higher modal frequencies. Active noise control obtained for the stiffened double wall configurations was less than for the unstiffened cylinder. In all cases, the acoustic control monopoles controlled the sound transmission into the interior better than the structural control forces.

Conformational Structure of Tyrosine, Tyrosyl-Glycine, and Tyrosyl-Glycyl-Glycine by Double Resonance Spectroscopy

NASA Technical Reports Server (NTRS)

Abo-Riziq, Ali; Grace, Louis; Crews, Bridgit; Callahan, Michael P,; van Mourik, Tanja; de Vries, Mattanjah S,

2011-01-01

We investigated the variation in conformation for the amino acid tyrosine (Y), alone and in the small peptides tyrosine-glycine (YC) and tyrosine-glycine-glycine (YGG), in the gas phase by using UV-UV and IR-UV double resonance spectroscopy and density functional theory calculations. For tyrosine we found seven different conformations, for YG we found four different conformations, and for YGG we found three different conformations. As the peptides get larger, we observe fewer stable conformers, despite the increasing complexity and number of degrees of freedom. We find structural trends similar to those in phenylalanine-glycine glycine (FGG) and tryptophan-glycine-glycine (WGG)j however) the effect of dispersive forces in FGG for stabilizing a folded structure is replaced by that of hydrogen bonding in YGG.

Physics for clinicians: Fluid-attenuated inversion recovery (FLAIR) and double inversion recovery (DIR) Imaging.

PubMed

Saranathan, Manojkumar; Worters, Pauline W; Rettmann, Dan W; Winegar, Blair; Becker, Jennifer

2017-12-01

A pedagogical review of fluid-attenuated inversion recovery (FLAIR) and double inversion recovery (DIR) imaging is conducted in this article. The basics of the two pulse sequences are first described, including the details of the inversion preparation and imaging sequences with accompanying mathematical formulae for choosing the inversion time in a variety of scenarios for use on clinical MRI scanners. Magnetization preparation (or T2prep), a strategy for improving image signal-to-noise ratio and contrast and reducing T 1 weighting at high field strengths, is also described. Lastly, image artifacts commonly associated with FLAIR and DIR are described with clinical examples, to help avoid misdiagnosis. 5 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1590-1600. © 2017 International Society for Magnetic Resonance in Medicine.

Staphylococcus aureus Peptidoglycan Stem Packing by Rotational-Echo Double Resonance NMR Spectroscopy

PubMed Central

Kim, Sung Joon; Singh, Manmilan; Preobrazhenskaya, Maria; Schaefer, Jacob

2013-01-01

Staphylococcus aureus grown in the presence of an alanine-racemase inhibitor was labeled with D-[1-13C]alanine and L-[15N]alanine to characterize some details of the peptidoglycan tertiary structure. Rotational-echo double-resonance NMR of intact whole cells was used to measure internuclear distances between 13C and 15N of labeled amino acids incorporated in the peptidoglycan, and from those labels to 19F of a glycopeptide drug specifically bound to the peptidoglycan. The observed 13C-15N average distance of 4.1 to 4.4 Å between D- and L-alanines in nearest-neighbor peptide stems is consistent with a local, tightly packed, parallel-stem architecture for a repeating structural motif within the peptidoglycan of S. aureus. PMID:23617832

Millimeter-band oscillations based on resonant tunneling in a double-barrier diode at room temperature

NASA Technical Reports Server (NTRS)

Brown, E. R.; Sollner, T. C. L. G.; Goodhue, W. D.; Parker, C. D.

1987-01-01

A double-barrier diode at room temperature has yielded oscillations with fundamental frequencies up to 56 GHz and second harmonics up to 87 GHz. The output powers at these frequencies were about 60 and 18 microW, respectively. These results are attributed to a recent improvement in the material parameters of the device and to the integration of the device into a waveguide resonator. The most successful diode to date has thin (about 1.5 nm) AlAs barriers, a 4.5-nm-wide GaAs quantum well, and 2 x 10 to the 17th/cu cm doping concentration in the n-GaAs outside the barriers. This particular diode is expected to oscillate at frequencies higher than those achieved by any reported p-n tunnel diode.

Diode end pumped laser and harmonic generator using same

NASA Technical Reports Server (NTRS)

Byer, Robert L. (Inventor); Dixon, George J. (Inventor); Kane, Thomas J. (Inventor)

1988-01-01

A second harmonic, optical generator is disclosed in which a laser diode produces an output pumping beam which is focused by means of a graded, refractive index rod lens into a rod of lasant material, such as Nd:YAG, disposed within an optical resonator to pump the lasant material and to excite the optical resonator at a fundamental wavelength. A non-linear electro-optic material such as MgO:LiNbO.sub.3 is coupled to the excited, fundamental mode of the optical resonator to produce a non-linear interaction with the fundamental wavelength producing a harmonic. In one embodiment, the gain medium and the non-linear material are disposed within an optical resonator defined by a pair of reflectors, one of which is formed on a face of the gain medium and the second of which is formed on a face of the non-linear medium. In another embodiment, the non-linear, electro-optic material is doped with the lasant ion such that the gain medium and the non-linear doubling material are co-extensive in volume. In another embodiment, a non-linear, doubling material is disposed in an optical resonator external of the laser gai medium for improved stability of the second harmonic generation process. In another embodiment, the laser gain medium andthe non-linear material are bonded together by means of an optically transparent cement to form a mechanically stable, monolithic structure. In another embodiment, the non-linear material has reflective faces formed thereon to define a ring resonator to decouple reflections from the non-linear medium back to the gain medium for improved stability.

Toward reliable modeling of S-nitrosothiol chemistry: Structure and properties of methyl thionitrite (CH3SNO), an S-nitrosocysteine model

NASA Astrophysics Data System (ADS)

Khomyakov, Dmitry G.; Timerghazin, Qadir K.

2017-07-01

Methyl thionitrite CH3SNO is an important model of S-nitrosated cysteine aminoacid residue (CysNO), a ubiquitous biological S-nitrosothiol (RSNO) involved in numerous physiological processes. As such, CH3SNO can provide insights into the intrinsic properties of the —SNO group in CysNO, in particular, its weak and labile S—N bond. Here, we report an ab initio computational investigation of the structure and properties of CH3SNO using a composite Feller-Peterson-Dixon scheme based on the explicitly correlated coupled cluster with single, double, and perturbative triple excitations calculations extrapolated to the complete basis set limit, CCSD(T)-F12/CBS, with a number of additive corrections for the effects of quadruple excitations, core-valence correlation, scalar-relativistic and spin-orbit effects, as well as harmonic zero-point vibrational energy with an anharmonicity correction. These calculations suggest that the S—N bond in CH3SNO is significantly elongated (1.814 Å) and has low stretching frequency and dissociation energy values, νS—N = 387 cm-1 and D0 = 32.4 kcal/mol. At the same time, the S—N bond has a sizable rotation barrier, △E0≠ = 12.7 kcal/mol, so CH3SNO exists as a cis- or trans-conformer, the latter slightly higher in energy, △E0 = 1.2 kcal/mol. The S—N bond properties are consistent with the antagonistic nature of CH3SNO, whose resonance representation requires two chemically opposite (antagonistic) resonance structures, CH3—S+=N—O- and CH3—S-/NO+, which can be probed using external electric fields and quantified using the natural resonance theory approach (NRT). The calculated S—N bond properties slowly converge with the level of correlation treatment, with the recently developed distinguished cluster with single and double excitations approximation (DCSD-F12) performing significantly better than the coupled cluster with single and double excitations (CCSD-F12), although still inferior to the CCSD(T)-F12 method that includes perturbative triple excitations. Double-hybrid density functional theory (DFT) calculations with mPW2PLYPD/def2-TZVPPD reproduce well the geometry, vibrational frequencies, and the S—N bond rotational barrier in CH3SNO, while hybrid DFT calculations with PBE0/def2-TZVPPD give a better S—N bond dissociation energy.

The use of a selective saturation pulse to suppress t1 noise in two-dimensional (1)H fast magic angle spinning solid-state NMR spectroscopy.

PubMed

Robertson, Aiden J; Pandey, Manoj Kumar; Marsh, Andrew; Nishiyama, Yusuke; Brown, Steven P

2015-11-01

A selective saturation pulse at fast magic angle spinning (MAS) frequencies (60+kHz) suppresses t1 noise in the indirect dimension of two-dimensional (1)H MAS NMR spectra. The method is applied to a synthetic nucleoside with an intense methyl (1)H signal due to triisopropylsilyl (TIPS) protecting groups. Enhanced performance in terms of suppressing the methyl signal while minimising the loss of signal intensity of nearby resonances of interest relies on reducing spin diffusion--this is quantified by comparing two-dimensional (1)H NOESY-like spin diffusion spectra recorded at 30-70 kHz MAS. For a saturation pulse centred at the methyl resonance, the effect of changing the nutation frequency at different MAS frequencies as well as the effect of changing the pulse duration is investigated. By applying a pulse of duration 30 ms and nutation frequency 725 Hz at 70 kHz MAS, a good compromise of significant suppression of the methyl resonance combined with the signal intensity of resonances greater than 5 ppm away from the methyl resonance being largely unaffected is achieved. The effectiveness of using a selective saturation pulse is demonstrated for both homonuclear (1)H-(1)H double quantum (DQ)/single quantum (SQ) MAS and (14)N-(1)H heteronuclear multiple quantum coherence (HMQC) two-dimensional solid-state NMR experiments. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Spectral editing of weakly coupled spins using variable flip angles in PRESS constant echo time difference spectroscopy: Application to GABA

NASA Astrophysics Data System (ADS)

Snyder, Jeff; Hanstock, Chris C.; Wilman, Alan H.

2009-10-01

A general in vivo magnetic resonance spectroscopy editing technique is presented to detect weakly coupled spin systems through subtraction, while preserving singlets through addition, and is applied to the specific brain metabolite γ-aminobutyric acid (GABA) at 4.7 T. The new method uses double spin echo localization (PRESS) and is based on a constant echo time difference spectroscopy approach employing subtraction of two asymmetric echo timings, which is normally only applicable to strongly coupled spin systems. By utilizing flip angle reduction of one of the two refocusing pulses in the PRESS sequence, we demonstrate that this difference method may be extended to weakly coupled systems, thereby providing a very simple yet effective editing process. The difference method is first illustrated analytically using a simple two spin weakly coupled spin system. The technique was then demonstrated for the 3.01 ppm resonance of GABA, which is obscured by the strong singlet peak of creatine in vivo. Full numerical simulations, as well as phantom and in vivo experiments were performed. The difference method used two asymmetric PRESS timings with a constant total echo time of 131 ms and a reduced 120° final pulse, providing 25% GABA yield upon subtraction compared to two short echo standard PRESS experiments. Phantom and in vivo results from human brain demonstrate efficacy of this method in agreement with numerical simulations.

Reverse resonance in stock prices of financial system with periodic information

NASA Astrophysics Data System (ADS)

Li, Jiang-Cheng; Mei, Dong-Cheng

2013-07-01

We investigate the stochastic resonance of the stock prices in a finance system with the Heston model. The extrinsic and intrinsic periodic information are introduced into the stochastic differential equations of the Heston model for stock price by focusing on the signal power amplification (SPA). We find that for both cases of extrinsic and intrinsic periodic information a phenomenon of reverse resonance emerges in the behaviors of SPA as a function of the system and external driving parameters. Moreover, in both cases, a phenomenon of double reverse resonance is observed in the behavior of SPA versus the amplitude of volatility fluctuations, by increasing the cross correlation between the noise sources in the Heston model.

Compensating amplitude-dependent tune-shift without driving fourth-order resonances

NASA Astrophysics Data System (ADS)

Ögren, J.; Ziemann, V.

2017-10-01

If octupoles are used in a ring to correct the amplitude-dependent tune-shift one normally tries to avoid that the octupoles drive additional resonances. Here we consider the optimum placement of octupoles that only affects the amplitude-dependent tune-shift, but does not drive fourth-order resonances. The simplest way turns out to place three equally powered octupoles with 60 ° phase advance between adjacent magnets. Using two such octupole triplets separated by a suitable phase advance cancels all fourth-order resonance driving terms and forms a double triplet we call a six-pack. Using three six-packs at places with different ratios of the beta functions allows to independently control all amplitude-dependent tune-shift terms without exciting additional fourth-order resonances in first order of the octupole excitation.

Acoustic superlens using Helmholtz-resonator-based metamaterials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Xishan; Yin, Jing; Yu, Gaokun, E-mail: gkyu@ouc.edu.cn

2015-11-09

Acoustic superlens provides a way to overcome the diffraction limit with respect to the wavelength of the bulk wave in air. However, the operating frequency range of subwavelength imaging is quite narrow. Here, an acoustic superlens is designed using Helmholtz-resonator-based metamaterials to broaden the bandwidth of super-resolution. An experiment is carried out to verify subwavelength imaging of double slits, the imaging of which can be well resolved in the frequency range from 570 to 650 Hz. Different from previous works based on the Fabry-Pérot resonance, the corresponding mechanism of subwavelength imaging is the Fano resonance, and the strong coupling between themore » neighbouring Helmholtz resonators separated at the subwavelength interval leads to the enhanced sound transmission over a relatively wide frequency range.« less

Nested trampoline resonators for optomechanics

NASA Astrophysics Data System (ADS)

Weaver, M. J.; Pepper, B.; Luna, F.; Buters, F. M.; Eerkens, H. J.; Welker, G.; Perock, B.; Heeck, K.; de Man, S.; Bouwmeester, D.

2016-01-01

Two major challenges in the development of optomechanical devices are achieving a low mechanical and optical loss rate and vibration isolation from the environment. We address both issues by fabricating trampoline resonators made from low pressure chemical vapor deposition Si3N4 with a distributed Bragg reflector mirror. We design a nested double resonator structure with 80 dB of mechanical isolation from the mounting surface at the inner resonator frequency, and we demonstrate up to 45 dB of isolation at lower frequencies in agreement with the design. We reliably fabricate devices with mechanical quality factors of around 400 000 at room temperature. In addition, these devices were used to form optical cavities with finesse up to 181 000 ± 1000. These promising parameters will enable experiments in the quantum regime with macroscopic mechanical resonators.

Phosphorescence/microwave double-resonance spectra of tryptophan perturbed by methylmercury(II).

PubMed Central

Davis, J M; Maki, A H

1982-01-01

Amplitude-modulated phosphorescence/microwave double-resonance (AM-PMDR) spectra are reported for complexes of methylmercury(II) cation, designated CH3Hg(II), with tryptophan and glyceraldehyde-3-phosphate dehydrogenase (GPDHase; from rabbit muscle). Wavelength shifts are observed in the AM-PMDR spectra of CH3Hg(II)-tryptophan, which are obtained by microwave pumping in distinct zero-field D + E magnetic resonance transitions, demonstrating that AM-PMDR can be used to display selectively the phosphorescence spectra of structurally distinct complexes with different zero-field splittings. The AM-PMDR spectra accurately represent the phosphorescence of CH3Hg(II)-tryptophan. Binding of CH3Hg(II) to a cysteine site of GDPHase perturbs the luminescence of one of the two optically resolved tryptophan. The AM-PMDR spectrum of the perturbed tryptophan is obtained by microwave pumping of the D + E magnetic resonance signal, which can be observed optically only in the presence of a heavy atom perturbation. The resulting spectrum is broadened and shifted to the blue relative to the corresponding tryptophan phosphorescence spectrum of the uncomplexed enzyme. Comparison of the AM-PMDR spectra of CH3Hg(II)-tryptophan and CH3Hg(II)-GPDHase suggests that there are differences in the mechanisms of heavy atom perturbation in these complexes. PMID:6956860

Electron density distribution in BaPb{sub 1-x}Sb{sub x}O{sub 3} superconducting oxides studied by double nuclear magnetic resonance methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Piskunov, Yu. V., E-mail: piskunov@imp.uran.ru; Ogloblichev, V. V.; Arapova, I. Yu.

2011-11-15

The effect of charge disorder on the formation of an inhomogeneous state of the electron system in the conduction band in BaPb{sub 1-x}Sb{sub x}O{sub 3} superconducting oxides is investigated experimentally by NMR methods. The NMR spectra of {sup 17}O are measured systematically, and the contributions from {sup 17}O atoms with different cation nearest surroundings are identified. It is found that microscopic regions with an elevated spin density of charge carriers are formed within two coordination spheres near antimony ions. Nuclei of the superconducting phase of the oxide (regions with an elevated antimony concentration) microscopically distributed over the sample are detectedmore » in compounds with x = 0.25 and 0.33. Experiments in which a double resonance signal of the spin echo of {sup 17}O-{sup 207}Pb and {sup 17}O-{sup 121}Sb are measured in the metal phase of BaPb{sub 1-x}Sb{sub x}O{sub 3} oxides are carried out for the first time. The constants of indirect heteronuclear spin-spin {sup 17}O-{sup 207}Pb interaction are determined as functions of the local Knight shift {sub 207}Ks. The estimates of the constants of the indirect interaction between the nuclei of the nearest neighbors (O-Pb and Pb-Pb atoms) and analysis of evolution of the NMR spectra of {sup 17}O upon a change in the antimony concentration are convincing evidence in favor of the development of a microscopically inhomogeneous state of the electron system in the metal phase of BaPb{sub 1-x}Sb{sub x}O{sub 3} oxides.« less

Absorption coefficient and relative refractive index change for a double δ-doped GaAs MIGFET-like structure: Electric and magnetic field effects

NASA Astrophysics Data System (ADS)

Martínez-Orozco, J. C.; Rodríguez-Magdaleno, K. A.; Suárez-López, J. R.; Duque, C. A.; Restrepo, R. L.

2016-04-01

In this work we present theoretical results for the electronic structure as well as for the absorption coefficient and relative refractive index change for an asymmetric double δ-doped like confining potential in the active region of a Multiple Independent Gate Field Effect Transistor (MIGFET) system. We model the potential profile as a double δ-doped like potential profile between two Schottky (parabolic) potential barriers that are just the main characteristics of the MIGFET configuration. We investigate the effect of external electromagnetic fields in this kind of quantum structures, in particular we applied a homogeneous constant electric field in the growth direction z as well as a homogeneous constant magnetic field in the x-direction. In general we conclude that by applying electromagnetic fields we can modulate the resonant peaks of the absorption coefficient as well as their energy position. Also with such probes it is possible to control the nodes and amplitude of the relative refractive index changes related to resonant intersubband optical transitions.

Spectral features of the tunneling-induced transparency and the Autler-Townes doublet and triplet in a triple quantum dot.

PubMed

Luo, Xiao-Qing; Li, Zeng-Zhao; Jing, Jun; Xiong, Wei; Li, Tie-Fu; Yu, Ting

2018-02-15

We theoretically investigate the spectral features of tunneling-induced transparency (TIT) and Autler-Townes (AT) doublet and triplet in a triple-quantum-dot system. By analyzing the eigenenergy spectrum of the system Hamiltonian, we can discriminate TIT and double TIT from AT doublet and triplet, respectively. For the resonant case, the presence of the TIT does not exhibit distinguishable anticrossing in the eigenenergy spectrum in the weak-tunneling regime, while the occurrence of double anticrossings in the strong-tunneling regime shows that the TIT evolves to the AT doublet. For the off-resonance case, the appearance of a new detuning-dependent dip in the absorption spectrum leads to double TIT behavior in the weak-tunneling regime due to no distinguished anticrossing occurring in the eigenenergy spectrum. However, in the strong-tunneling regime, a new detuning-dependent dip in the absorption spectrum results in AT triplet owing to the presence of triple anticrossings in the eigenenergy spectrum. Our results can be applied to quantum measurement and quantum-optics devices in solid systems.

Evaluating charge noise acting on semiconductor quantum dots in the circuit quantum electrodynamics architecture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Basset, J.; Stockklauser, A.; Jarausch, D.-D.

2014-08-11

We evaluate the charge noise acting on a GaAs/GaAlAs based semiconductor double quantum dot dipole-coupled to the voltage oscillations of a superconducting transmission line resonator. The in-phase (I) and the quadrature (Q) components of the microwave tone transmitted through the resonator are sensitive to charging events in the surrounding environment of the double dot with an optimum sensitivity of 8.5×10{sup −5} e/√(Hz). A low frequency 1/f type noise spectrum combined with a white noise level of 6.6×10{sup −6} e{sup 2}/Hz above 1 Hz is extracted, consistent with previous results obtained with quantum point contact charge detectors on similar heterostructures. The slope ofmore » the 1/f noise allows to extract a lower bound for the double-dot charge qubit dephasing rate which we compare to the one extracted from a Jaynes-Cummings Hamiltonian approach. The two rates are found to be similar emphasizing that charge noise is the main source of dephasing in our system.« less

Double temporal sparsity based accelerated reconstruction of compressively sensed resting-state fMRI.

PubMed

Aggarwal, Priya; Gupta, Anubha

2017-12-01

A number of reconstruction methods have been proposed recently for accelerated functional Magnetic Resonance Imaging (fMRI) data collection. However, existing methods suffer with the challenge of greater artifacts at high acceleration factors. This paper addresses the issue of accelerating fMRI collection via undersampled k-space measurements combined with the proposed method based on l 1 -l 1 norm constraints, wherein we impose first l 1 -norm sparsity on the voxel time series (temporal data) in the transformed domain and the second l 1 -norm sparsity on the successive difference of the same temporal data. Hence, we name the proposed method as Double Temporal Sparsity based Reconstruction (DTSR) method. The robustness of the proposed DTSR method has been thoroughly evaluated both at the subject level and at the group level on real fMRI data. Results are presented at various acceleration factors. Quantitative analysis in terms of Peak Signal-to-Noise Ratio (PSNR) and other metrics, and qualitative analysis in terms of reproducibility of brain Resting State Networks (RSNs) demonstrate that the proposed method is accurate and robust. In addition, the proposed DTSR method preserves brain networks that are important for studying fMRI data. Compared to the existing methods, the DTSR method shows promising potential with an improvement of 10-12 dB in PSNR with acceleration factors upto 3.5 on resting state fMRI data. Simulation results on real data demonstrate that DTSR method can be used to acquire accelerated fMRI with accurate detection of RSNs. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

PubMed

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

2016-03-28

To use magnetic resonance-guided high intensity focused ultrasound (MRg-HIFU), magnetic resonance imaging (MRI) and histopathology for noninvasively ablating, quantifying and characterizing ablated renal tissue. Six anesthetized/mechanically-ventilated pigs underwent single/double renal sonication (n = 24) using a 3T-MRg-HIFU (1.1 MHz frequency and 3000J-4400J energies). T2-weighted fast spin echo (T2-W), perfusion saturation recovery gradient echo and contrast enhanced (CE) T1-weighted (T1-W) sequences were used for treatment planning, temperature monitoring, lesion visualization, characterization and quantification, respectively. Histopathology was conducted in excised kidneys to quantify and characterize cellular and vascular changes. Paired Student's t-test was used and a P-value < 0.05 was considered statistically significant. Ablated renal parenchyma could not be differentiated from normal parenchyma on T2-W or non-CE T1-W sequences. Ablated renal lesions were visible as hypoenhanced regions on perfusion and CE T1-W MRI sequences, suggesting perfusion deficits and necrosis. Volumes of ablated parenchyma on CE T1-W images in vivo (0.12-0.36 cm(3) for single sonication 3000J, 0.50-0.84 cm(3), for double 3000J, 0.75-0.78 cm(3) for single 4400J and 0.12-2.65 cm(3) for double 4400J) and at postmortem (0.23-0.52 cm(3), 0.25-0.82 cm(3), 0.45-0.68 cm(3) and 0.29-1.80 cm(3), respectively) were comparable. The ablated volumes on 3000J and 4400J double sonication were significantly larger than single (P < 0.01), thus, the volume and depth of ablated tissue depends on the applied energy and number of sonication. Macroscopic and microscopic examinations confirmed the locations and presence of coagulation necrosis, vascular damage and interstitial hemorrhage, respectively. Contrast enhanced MRI provides assessment of MRg-HIFU renal ablation. Histopathology demonstrated coagulation necrosis, vascular damage and confirmed the volume of damage seen on MRI.

l-Tryptophan Radical Cation Electron Spin Resonance Studies: Connecting Solution-derived Hyperfine Coupling Constants with Protein Spectral Interpretations

PubMed Central

Connor, Henry D.; Sturgeon, Bradley E.; Mottley, Carolyn; Sipe, Herbert J.; Mason, Ronald P.

2009-01-01

Fast-flow electron spin resonance (ESR) spectroscopy has been used to detect a free radical formed from the reaction of l-tryptophan with Ce4+ in an acidic aqueous environment. Computer simulations of the ESR spectra from l-tryptophan and several isotopically modified forms strongly support the conclusion that the l-tryptophan radical cation has been detected by ESR for the first time. The hyperfine coupling constants (HFCs) determined from the well-resolved isotropic ESR spectra support experimental and computational efforts to understand l-tryptophan's role in protein catalysis of oxidation-reduction processes. l-tryptophan HFCs facilitated the simulation of fast-flow ESR spectra of free radicals from two related compounds, tryptamine and 3-methylindole. Analysis of these three compounds' β-methylene hydrogen HFC data along with equivalent l-tyrosine data has led to a new computational method that can distinguish between these two amino acid free radicals in proteins without dependence on isotope labeling, electron nuclear double resonance or high-field ESR. This approach also produces geometric parameters (dihedral angles for the β-methylene hydrogens) which should facilitate protein site assignment of observed l-tryptophan radicals as has been done for l-tyrosine radicals. PMID:18433127

Dynamic conductivity modified by impurity resonant states in doping three-dimensional Dirac semimetals

NASA Astrophysics Data System (ADS)

Li, Shuai; Wang, Chen; Zheng, Shi-Han; Wang, Rui-Qiang; Li, Jun; Yang, Mou

2018-04-01

The impurity effect is studied in three-dimensional Dirac semimetals in the framework of a T-matrix method to consider the multiple scattering events of Dirac electrons off impurities. It has been found that a strong impurity potential can significantly restructure the energy dispersion and the density of states of Dirac electrons. An impurity-induced resonant state emerges and significantly modifies the pristine optical response. It is shown that the impurity state disturbs the common longitudinal optical conductivity by creating either an optical conductivity peak or double absorption jumps, depending on the relative position of the impurity band and the Fermi level. More importantly, these conductivity features appear in the forbidden region between the Drude and interband transition, completely or partially filling the Pauli block region of optical response. The underlying physics is that the appearance of resonance states as well as the broadening of the bands leads to a more complicated selection rule for the optical transitions, making it possible to excite new electron-hole pairs in the forbidden region. These features in optical conductivity provide valuable information to understand the impurity behaviors in 3D Dirac materials.

Investigation of change of tumor optical properties after laser-induced plasmon-resonant photothermal treatment of transplanted tumors in rats

NASA Astrophysics Data System (ADS)

Genin, Vadim D.; Genina, Elina A.; Bucharskaya, Alla B.; Tuchin, Valery V.; Khlebtsov, Nikolay G.; Terentyuk, Georgy S.; Bashkatov, Alexey N.

2018-04-01

The paper presents the investigation of change of tumor optical properties of the rat tumor doped by gold nanoparticles after laser-induced plasmon-resonant photothermal treatment. To obtain the model tumors the rats have been implanted by suspension of alveolar kidney cancer cells. An hour before the experiment the animals have been injected by the suspension of gold nanorods intratumorally. For irradiation a diode laser with wavelength 808 nm has been used. After the irradiation the tumor has been removed and sliced. Spectra of total and collimated transmission and diffuse reflectance of the samples of different layers of the tumors have been measured in the wavelength range 350-2500 nm. Absorption, scattering, reduced scattering coefficients and scattering anisotropy factor of tumor tissues have been calculated with inverse adding-doubling method. The results of the experiment have shown that after doping the tumor tissue by the plasmon resonant nanoparticles and NIR laser irradiating, there is the decreases of absorption as well as scattering properties of the tumor and surrounding tissues. However, despite the sufficiently high temperature on the surface (about 80°C), the changes in the center of the tumor are insignificant.

Profiling planktonic biomass using element-specific, multicomponent nuclear magnetic resonance spectroscopy.

PubMed

Komatsu, Takanori; Kobayashi, Toshiya; Hatanaka, Minoru; Kikuchi, Jun

2015-06-02

Planktonic metabolism plays crucial roles in Earth's elemental cycles. Chemical speciation as well as elemental stoichiometry is important for advancing our understanding of planktonic roles in biogeochemical cycles. In this study, a multicomponent solid-state nuclear magnetic resonance (NMR) approach is proposed for chemical speciation of cellular components, using several advanced NMR techniques. Measurements by ssNMR were performed on (13)C and (15)N-labeled Euglena gracilis, a flagellated protist. 3D dipolar-assisted rotational resonance, double-cross-polarization (1)H-(13)C correlation spectroscopy, and (1)H-(13)C solid-state heteronuclear single quantum correlation spectroscopy successively allowed characterization of cellular components. These techniques were then applied to E. gracilis cultured in high and low ammonium media to demonstrate the power of this method for profiling and comparing cellular components. Cellular NMR spectra indicated that ammonium induced both paramylon degradation and amination. Arginine was stored as a nitrogen reserve and ammonium replaced by arginine catabolism via the arginine dihydrolase pathway. (15)N and (31)P cellular ssNMR indicated arginine and polyphosphate accumulation in E. gracilis, respectively. This chemical speciation technique will contribute to environmental research by providing detailed information on environmental chemical properties.

Analysis of mode-locked and intracavity frequency-doubled Nd:YAG laser

NASA Technical Reports Server (NTRS)

Siegman, A. E.; Heritier, J.-M.

1980-01-01

The paper presents analytical and computer studies of the CW mode-locked and intracavity frequency-doubled Nd:YAG laser which provide new insight into the operation, including the detuning behavior, of this type of laser. Computer solutions show that the steady-state pulse shape for this laser is much closer to a truncated cosine than to a Gaussian; there is little spectral broadening for on-resonance operation; and the chirp is negligible. This leads to a simplified analytical model carried out entirely in the time domain, with atomic linewidth effects ignored. Simple analytical results for on-resonance pulse shape, pulse width, signal intensity, and harmonic conversion efficiency in terms of basic laser parameters are derived from this model. A simplified physical description of the detuning behavior is also developed. Agreement is found with experimental studies showing that the pulsewidth decreases as the modulation frequency is detuned off resonance; the harmonic power output initially increases and then decreases; and the pulse shape develops a sharp-edged asymmetry of opposite sense for opposite signs of detuning.

Direct Spectroscopic Detection of ATP Turnover Reveals Mechanistic Divergence of ABC Exporters.

PubMed

Collauto, Alberto; Mishra, Smriti; Litvinov, Aleksei; Mchaourab, Hassane S; Goldfarb, Daniella

2017-08-01

We have applied high-field (W-band) pulse electron-nuclear double resonance (ENDOR) and electron-electron double resonance (ELDOR)-detected nuclear magnetic resonance (EDNMR) to characterize the coordination sphere of the Mn 2+ co-factor in the nucleotide binding sites (NBSs) of ABC transporters. MsbA and BmrCD are two efflux transporters hypothesized to represent divergent catalytic mechanisms. Our results reveal distinct coordination of Mn 2+ to ATP and transporter residues in the consensus and degenerate NBSs of BmrCD. In contrast, the coordination of Mn 2+ at the two NBSs of MsbA is similar, which provides a mechanistic rationale for its higher rate constant of ATP hydrolysis relative to BmrCD. Direct detection of vanadate ion, trapped in a high-energy post-hydrolysis intermediate, further supports the notion of asymmetric hydrolysis by the two NBSs of BmrCD. The integrated spectroscopic approach presented here, which link energy input to conformational dynamics, can be applied to a variety of systems powered by ATP turnover. Copyright © 2017 Elsevier Ltd. All rights reserved.

Double Gamow-Teller Transitions and its Relation to Neutrinoless β β Decay

NASA Astrophysics Data System (ADS)

Shimizu, Noritaka; Menéndez, Javier; Yako, Kentaro

2018-04-01

We study the double Gamow-Teller (DGT) strength distribution of 48Ca with state-of-the-art large-scale nuclear shell model calculations. Our analysis shows that the centroid energy of the DGT giant resonance depends mostly on the isovector pairing interaction, while the resonance width is more sensitive to isoscalar pairing. Pairing correlations are also key in neutrinoless β β (0 ν β β ) decay. We find a simple relation between the centroid energy of the 48Ca DGT giant resonance and the 0 ν β β decay nuclear matrix element. More generally, we observe a very good linear correlation between the DGT transition to the ground state of the final nucleus and the 0 ν β β decay matrix element. The correlation, which originates on the dominant short-range character of both transitions, extends to heavier systems including several β β emitters and also holds in energy-density functional results. Our findings suggest that DGT experiments can be a very valuable tool to obtain information on the value of 0 ν β β decay nuclear matrix elements.

Electron volt spectroscopy on a pulsed neutron source

NASA Astrophysics Data System (ADS)

Newport, R. J.; Penfold, J.; Williams, W. G.

1984-07-01

The principal design aspects of a pulsed source neutron spectrometer in which the scattered neutron energy is determined by a resonance absorption filter difference method are discussed. Calculations of the accessible dynamic range, resolution and spectrum simulations are given for the spectrometer on a high intensity pulsed neutron source, such as the spallation neutron source (SNS) now being constructed at the Rutherford Appleton Laboratory. Special emphasis is made of the advantage gained by placing coarse and fixed energy-sensitive filters before and after the scatterer; these enhance the inelastic/elastic descrimination of the method. A brief description is given of a double difference filter method which gives a superior difference peak shape, as well as a better energy transfer resolution. Finally, some first results of scattering from zirconium hydride, obtained on a test spectrometer, are presented.

Non-resonant Nanoscale Extreme Light Confinement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Subramania, Ganapathi Subramanian; Huber, Dale L.

2014-09-01

A wide spectrum of photonics activities Sandia is engaged in such as solid state lighting, photovoltaics, infrared imaging and sensing, quantum sources, rely on nanoscale or ultrasubwavelength light-matter interactions (LMI). The fundamental understanding in confining electromagnetic power and enhancing electric fields into ever smaller volumes is key to creating next generation devices for these programs. The prevailing view is that a resonant interaction (e.g. in microcavities or surface-plasmon polaritions) is necessary to achieve the necessary light confinement for absorption or emission enhancement. Here we propose new paradigm that is non-resonant and therefore broadband and can achieve light confinement and fieldmore » enhancement in extremely small areas [~(λ/500)^2 ]. The proposal is based on a theoretical work[1] performed at Sandia. The paradigm structure consists of a periodic arrangement of connected small and large rectangular slits etched into a metal film named double-groove (DG) structure. The degree of electric field enhancement and power confinement can be controlled by the geometry of the structure. The key operational principle is attributed to quasistatic response of the metal electrons to the incoming electromagnetic field that enables non-resonant broadband behavior. For this exploratory LDRD we have fabricated some test double groove structures to enable verification of quasistatic electronic response in the mid IR through IR optical spectroscopy. We have addressed some processing challenges in DG structure fabrication to enable future design of complex sensor and detector geometries that can utilize its non-resonant field enhancement capabilities.].« less

H(C)P and H(P)C triple-resonance experiments at natural abundance employing long-range couplings.

PubMed

Malon, Michal; Koshino, Hiroyuki

2007-09-01

Modified two-dimensional (2D) triple-resonance H(C)P and H(P)C experiments based on INEPT/HMQC and double-INEPT schemes are applied to the study of organophosphorus compounds at natural abundances. The implementation of effective (1)H--(13)C gradient selection, additional purging pulsed field gradients, spinlock pulses, and improved phase cycling is demonstrated to allow weak correlation signals based on long-range couplings to be readily observed. Through the combination of two heteronuclear long-range coupling constants, (n)J(CH) and (n)J(PC) in H(C)P experiments or (n)J(PH) and (n)J(PC) in H(P)C experiments, protons can be correlated to a second heteronucleus through 4-7 chemical bonds. These experiments thus overcome the inherit limitations of classical (1)H-X HMBC experiments, which require a nonzero value of the heteronuclear coupling constant (n)J(XH). Ultra-broadband inversion composite pulses are successfully employed in the H(P)C INEPT/HMQC and H(P)C double-INEPT pulse sequences to increase the utility of the experiments and the quality of obtained spectra. This work extends and completes a set of 2D phase-sensitive triple-resonance experiments applicable at natural abundances, and also offers insight into the methodology of triple-resonance experiments and the application of pulsed field gradients. A one-dimensional triple-resonance experiment employing carbon detection is suggested for accurate determination of small (n)J(PC).

A numerical study of active structural acoustic control in a stiffened, double wall cylinder

NASA Technical Reports Server (NTRS)

Grosveld, Ferdinand W.; Coats, T. J.; Lester, H. C.; Silcox, R. J.

1994-01-01

It is demonstrated that active structural acoustic control of complex structural/acoustic coupling can be numerically modeled using finite element and boundary element techniques in conjunction with an optimization procedure to calculate control force amplitudes. Appreciable noise reduction is obtained when the structure is excited at a structural resonance of the outer shell or an acoustic resonance of the inner cavity. Adding ring stiffeners as a connection between the inner and outer shells provides an additional structural transmission path to the interior cavity and coupled the modal behavior of the inner and outer shells. For the case of excitation at the structural resonance of the unstiffened outer shell, adding the stiffeners raises the structural resonance frequencies. The effectiveness of the control forces is reduced due to the off resonance structural response. For excitation at an acoustic cavity resonance, the controller effectiveness is enhanced.

Vibronic coupling and selectivity of vibrational excitation in the negative ion resonances of ozone

NASA Astrophysics Data System (ADS)

Allan, Michael; Popovic̀, Duška B.

1997-04-01

A recent experimental paper reported two shape resonances in electron impact on ozone, A 1 and B 2, both causing vibrational excitation with a distinct pattern of selectivity. The present Letter attempts to rationalize this selectivity using approximate potential curves, calculated for the A 1 and B 2 resonances by adding the SCF energy of neutral ozone to electron attachment energies calculated from ab initio virtual orbital energies using the Koopmans' theorem and an empirical scaling relation. The slopes of the curves explain the efficient excitation of the symmetric stretch by both resonances and the lack of the bending excitation by the B 2 resonance. The A 1 and B 2 resonances are strongly coupled by the b 2 antisymmetric stretch vibration, causing a double minimum on the lower surface. Nonadiabatic effects caused by the strong vibronic coupling explain the observed excitation of the antisymmetric stretch vibration.

Kinetically and thermodynamically stable isomers of thorium chelates of polyaza polycarboxylic macrocycles

NASA Astrophysics Data System (ADS)

Jacques, Vincent; Desreux, Jean F.

1994-10-01

The solution conformation of the thorium(IV) complexes of two polyaza polycarboxylic macrocycles, DOTA and HEHA (1,4,7,10-tetraazacyclododecane-N, N', N(double prime), N(triple prime)-tetraacetic acid and 1,4,7,10,13,16-hexaazacyclooctadecane-N, N', N(double prime), N(triple prime), N(double prime)(double prime), N(double prime)(triple prime)-hexaacetic acid), was investigated by one- and two-dimensional nuclear magnetic resonance spectroscopy. ThHEHA(2+) forms a kinetically stable topomer of C2 symmetry and a thermodynamically stable topomer of S6 symmetry. Both complexes are assigned an icosahedral geometry. The activation energy for the intermolecular exchange is very high (214 kJ/mol). The behavior of ThHEHA(2+) contrasts with the properties of the other Th(IV) chelates that are known to be fluxional.

A new hydrodynamic analysis of double layers

NASA Technical Reports Server (NTRS)

Hora, Heinrich

1987-01-01

A genuine two-fluid model of plasmas with collisions permits the calculation of dynamic (not necessarily static) electric fields and double layers inside of plasmas including oscillations and damping. For the first time a macroscopic model for coupling of electromagnetic and Langmuir waves was achieved with realistic damping. Starting points were laser-produced plasmas showing very high dynamic electric fields in nonlinear force-produced cavitous and inverted double layers in agreement with experiments. Applications for any inhomogeneous plasma as in laboratory or in astrophysical plasmas can then be followed up by a transparent hydrodynamic description. Results are the rotation of plasmas in magnetic fields and a new second harmonic resonance, explanation of the measured inverted double layers, explanation of the observed density-independent, second harmonics emission from laser-produced plasmas, and a laser acceleration scheme by the very high fields of the double layers.

Paramagnetic resonance studies of bistrispyrazolylborate cobalt(II) and related derivatives

NASA Astrophysics Data System (ADS)

Myers, William K.

Herein, a systematic frozen solution electron-nuclear double resonance (ENDOR) study of high-spin Co(II) complexes is reported to demonstrate the efficacy of methyl substitutions as a means of separating dipolar and contact coupling, and further, to increase the utility of high-spin Co(II) as a spectroscopic probe for the ubiquitous, but spectroscopically-silent Zn(II) metalloenzymes. High-spin (hs) Co(II) has been subject of paramagnetic resonance studies for over 50 years and has been used as a spectroscopic probe for Zn metalloenzymes for over 35 years. However, as will be seen, the inherent complexity of the electronic properties of the cobaltous ion remains to be exploited to offer a wealth of information on Zn(II) enzymatic environments. Specifically, ENDOR measurements on bistrispyrazolylborate cobalt(II) confirm the utility of the novel method of methyl substitution to differentiate dipolar and Fermi contact couplings. An extensive set of electron paramagnetic resonance (EPR) simulations were performed. Software was developed to implement an ENDOR control interface. Finally, proton relaxation measurements were made in the range of 12-42 MHz, which were accounted for with the large g-value anisotropy of the Co(II) compounds. Taken as a whole, these studies point to the rich complexity of the electronic structure of high-spin cobalt(II) and, when sufficiently well-characterized, the great utility it has as a surrogate of biological Zn(II).

Double Aortic Arch With Previously Undescribed Head and Neck Vessel Branching.

PubMed

Hashemi, Sassan; Parks, W James; Sallee, Denver; Slesnick, Timothy

2017-04-01

Vascular ring in the form of a double aortic arch is a rare anomaly that can cause airway compression. It occasionally occurs with unusual head and neck vessel branching. A 5-year-old boy with chronic respiratory symptoms was referred because of a tracheal indentation on his chest x-ray. Magnetic resonance imaging showed a double aortic arch with arch origins of a common carotid, vertebral, and subclavian on the right and internal and external carotids, vertebral, and subclavian arteries on the left. Our case represents, to our knowledge, the first report of a double aortic arch with 7 separate vessels arising from the transverse arches. Copyright © 2016 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

Electron-Atom Ionization Calculations using Propagating Exterior Complex Scaling

NASA Astrophysics Data System (ADS)

Bartlett, Philip

2007-10-01

The exterior complex scaling method (Science 286 (1999) 2474), pioneered by Rescigno, McCurdy and coworkers, provided highly accurate ab initio solutions for electron-hydrogen collisions by directly solving the time-independent Schr"odinger equation in coordinate space. An extension of this method, propagating exterior complex scaling (PECS), was developed by Bartlett and Stelbovics (J. Phys. B 37 (2004) L69, J. Phys. B 39 (2006) R379) and has been demonstrated to provide computationally efficient and accurate calculations of ionization and scattering cross sections over a large range of energies below, above and near the ionization threshold. An overview of the PECS method for three-body collisions and the computational advantages of its propagation and iterative coupling techniques will be presented along with results of: (1) near-threshold ionization of electron-hydrogen collisions and the Wannier threshold laws, (2) scattering cross section resonances below the ionization threshold, and (3) total and differential cross sections for electron collisions with excited targets and hydrogenic ions from low through to high energies. Recently, the PECS method has been extended to solve four-body collisions using time-independent methods in coordinate space and has initially been applied to the s-wave model for electron-helium collisions. A description of the extensions made to the PECS method to facilitate these significantly more computationally demanding calculations will be given, and results will be presented for elastic, single-excitation, double-excitation, single-ionization and double-ionization collisions.

Influence of frequency tuning and double-frequency heating on ions extracted from an electron cyclotron resonance ion source

NASA Astrophysics Data System (ADS)

Maimone, F.; Celona, L.; Lang, R.; Mäder, J.; Roßbach, J.; Spädtke, P.; Tinschert, K.

2011-12-01

The electromagnetic field within the plasma chamber of an electron cyclotron resonance ion source (ECRIS) and the properties of the plasma waves affect the plasma properties and ion beam production. We have experimentally investigated the "frequency tuning effect" and "double frequency heating" on the CAPRICE ECRIS device. A traveling wave tube amplifier, two microwave sweep generators, and a dedicated experimental set-up were used to carry out experiments in the 12.5-16.5 GHz frequency range. During the frequency sweeps the evolution of the intensity and shape of the extracted argon beam were measured together with the microwave reflection coefficient. A range of different ion source parameter settings was used. Here we describe these experiments and the resultant improved understanding of these operational modes of the ECR ion source.

Influence of frequency tuning and double-frequency heating on ions extracted from an electron cyclotron resonance ion source.

PubMed

Maimone, F; Celona, L; Lang, R; Mäder, J; Rossbach, J; Spädtke, P; Tinschert, K

2011-12-01

The electromagnetic field within the plasma chamber of an electron cyclotron resonance ion source (ECRIS) and the properties of the plasma waves affect the plasma properties and ion beam production. We have experimentally investigated the "frequency tuning effect" and "double frequency heating" on the CAPRICE ECRIS device. A traveling wave tube amplifier, two microwave sweep generators, and a dedicated experimental set-up were used to carry out experiments in the 12.5-16.5 GHz frequency range. During the frequency sweeps the evolution of the intensity and shape of the extracted argon beam were measured together with the microwave reflection coefficient. A range of different ion source parameter settings was used. Here we describe these experiments and the resultant improved understanding of these operational modes of the ECR ion source.

Intersubunit distances in full-length, dimeric, bacterial phytochrome Agp1, as measured by pulsed electron-electron double resonance (PELDOR) between different spin label positions, remain unchanged upon photoconversion.

PubMed

Kacprzak, Sylwia; Njimona, Ibrahim; Renz, Anja; Feng, Juan; Reijerse, Edward; Lubitz, Wolfgang; Krauss, Norbert; Scheerer, Patrick; Nagano, Soshichiro; Lamparter, Tilman; Weber, Stefan

2017-05-05

Bacterial phytochromes are dimeric light-regulated histidine kinases that convert red light into signaling events. Light absorption by the N-terminal photosensory core module (PCM) causes the proteins to switch between two spectrally distinct forms, Pr and Pfr, thus resulting in a conformational change that modulates the C-terminal histidine kinase region. To provide further insights into structural details of photoactivation, we investigated the full-length Agp1 bacteriophytochrome from the soil bacterium Agrobacterium fabrum using a combined spectroscopic and modeling approach. We generated seven mutants suitable for spin labeling to enable application of pulsed EPR techniques. The distances between attached spin labels were measured using pulsed electron-electron double resonance spectroscopy to probe the arrangement of the subunits within the dimer. We found very good agreement of experimental and calculated distances for the histidine-kinase region when both subunits are in a parallel orientation. However, experimental distance distributions surprisingly showed only limited agreement with either parallel- or antiparallel-arranged dimer structures when spin labels were placed into the PCM region. This observation indicates that the arrangements of the PCM subunits in the full-length protein dimer in solution differ significantly from that in the PCM crystals. The pulsed electron-electron double resonance data presented here revealed either no or only minor changes of distance distributions upon Pr-to-Pfr photoconversion. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Prenatal and accurate perinatal diagnosis of type 2 H or ductular duplicate gallbladder.

PubMed

Maggi, Umberto; Farris, Giorgio; Carnevali, Alessandra; Borzani, Irene; Clerici, Paola; Agosti, Massimo; Rossi, Giorgio; Leva, Ernesto

2018-02-07

Double gallbladder is a rare biliary anomaly. Perinatal diagnosis of the disorder has been reported in only 6 cases, and in 5 of them the diagnosis was based on ultrasound imaging only. However, the ultrasound technique alone does not provide a sufficiently precise description of cystic ducts and biliary anatomy, an information that is crucial for a correct classification and for a possible future surgery. At 21 weeks of gestational age of an uneventful pregnancy in a 38 year old primipara mother, a routine ultrasound screening detected a biliary anomaly in the fetus suggestive of a double gallbladder. A neonatal abdominal ultrasonography performed on postnatal day 2 confirmed the diagnosis. On day 12 the newborn underwent a Magnetic Resonance Cholangiopancreatography (MRCP) that clearly characterized the anatomy of the anomaly: both gallbladders had their own cystic duct and both had a separate insertion in the main biliary duct. We report a case of early prenatal suspected duplicate gallbladder that was confirmed by a neonatal precise diagnosis of a Type 2, H or ductular duplicate gallbladder, using for the first time 3D images of Magnetic resonance cholangiopancreatography in a newborn. An accurate anatomical diagnosis is mandatory in patients undergoing a possible future cholecystectomy, to avoid surgical complications or reoperations. Therefore, in case of a perinatal suspicion of a double gallbladder, neonates should undergo a Magnetic resonance cholangiopancreatography. A review of the Literature about this variant is included.

Dual traveling wave rotary ultrasonic motor with single active vibrator

NASA Astrophysics Data System (ADS)

An, Dawei; Yang, Ming; Zhuang, Xiaoqi; Yang, Tianyue; Meng, Fan; Dong, Zhaopeng

2017-04-01

Traveling wave rotary ultrasonic motor with double vibrators can improve the output performance effectively. However, the rotor has to be energized through a slip ring, which increases the complexity and reduces the reliability. Inheriting the concept of two traveling waves propagating in the stator and rotor, a dual traveling wave rotary ultrasonic motor energized only in the stator is proposed. By analyzing the oscillatory differential equation and the contact particles motion, a traveling wave is found in the rotor and the drive mechanism of dual traveling wave is studied. With the resonant rotor adopted, the consistent eigenfrequencies are calculated by finite element method and verified by an impedance analyzer. The performance experiment presents that the dual traveling wave rotary ultrasonic motor is superior to the motor with single traveling wave. The no-load speed is 60 rpm and the stalling torque is 0.85 Nm. Additionally, compared with a reported motor with double vibrators, the proposed motor presents the better output performance and the simpler design.

A comparative study between different approaches to improve the RCS of a compact double-layer absorber

NASA Astrophysics Data System (ADS)

El-Hakim, H. A.; Mahmoud, K. R.

2017-10-01

In this paper, straightforward and efficient techniques have been addressed into double-layer structure to enlarge the operating bandwidth to include the X, Ku and K bands, in addition to increase the electromagnetic wave absorption for wide varieties of incident angles and both polarization types. To increase the band-stop resonating frequency up to 26 GHz, an additional layer of meta-surface, circuit analog radar absorber material (CAR), or a thin radar absorber material (RAM) layer is engineered. The synthesized layers are designed based on optimization process with genetic algorithm (GA) through numerical technique (Ansoft design software HFSS) for both transmission line (T.L) and the free space method to get optimal material properties suitable for the design. For different approaches, the designed structures achieved a reflectivity value less than -16 dB on average in the desired bandwidth from 8 to 26 GHz for TE/TM modes with incidence angle up to 50o.

Influence of initial stress on the vibration of double-piezoelectric-nanoplate systems with various boundary conditions using DQM

NASA Astrophysics Data System (ADS)

Asemi, S. R.; Farajpour, A.; Asemi, H. R.; Mohammadi, M.

2014-09-01

In this paper, a nonlocal continuum plate model is developed for the transverse vibration of double-piezoelectric-nanoplate systems (DPNPSs) with initial stress under an external electric voltage. The Pasternak foundation model is employed to take into account the effect of shearing between the two piezoelectric nanoplates in combination with normal behavior of coupling elastic medium. Size effects are taken into consideration using nonlocal continuum mechanics. Hamilton's principle is used to derive the differential equations of motion. The governing equations are solved for various boundary conditions by using the differential quadrature method (DQM). In addition, exact solutions are presented for the natural frequencies and critical electric voltages of DPNPS under biaxial prestressed conditions in in-phase and out-of-phase vibrational modes. It is shown that the natural frequencies of the DPNPS are quite sensitive to both nonlocal parameter and initial stress. The effects of in-plane preload and small scale are very important in the resonance mode of smart nanostructures using piezoelectric nanoplates.

Effect of proton transfer on the electronic coupling in DNA

NASA Astrophysics Data System (ADS)

Rak, Janusz; Makowska, Joanna; Voityuk, Alexander A.

2006-06-01

The effects of single and double proton transfer within Watson-Crick base pairs on donor-acceptor electronic couplings, Vda, in DNA are studied on the bases of quantum chemical calculations. Four dimers [AT,AT], [GC,GC], [GC,AT] and [GC,TA)] are considered. Three techniques - the generalized Mulliken-Hush scheme, the fragment charge method and the diabatic states method - are employed to estimate Vda for hole transfer between base pairs. We show that both single- and double proton transfer (PT) reactions may substantially affect the electronic coupling in DNA. The electronic coupling in [AT,AT] is predicted to be most sensitive to PT. Single PT within the first base pair in the dimer leads to increase in the hole transfer efficiency by a factor of 4, while proton transfer within the second pair should substantially, by 2.7 times, decrease the rate of charge transfer. Thus, directional asymmetry of the PT effects on the electronic coupling is predicted. The changes in the Vda matrix elements correlate with the topological properties of orbitals of donor and acceptor and can be qualitatively rationalized in terms of resonance structures of donor and acceptor. Atomic pair contributions to the Vda matrix elements are also analyzed.

Modal analysis on resonant excitation of two-dimensional waveguide grating filters

NASA Astrophysics Data System (ADS)

Zhou, Jianyu; Sang, Tian; Li, Junlang; Wang, Rui; Wang, La; Wang, Benxin; Wang, Yueke

2017-12-01

Modal analysis on resonant excitation of two-dimensional (2-D) waveguide grating filters (WGFs) is proposed. It is shown that the 2-D WGFs can support the excitation of a resonant pair, and the locations of the resonant pair arising from the TE and TM guided-mode resonances (GMRs) can be estimated accurately based on the modal analysis. Multichannel filtering using the resonant pair is investigated, and the antireflection (AR) design of the 2-D WGFs is also studied. It is shown that the reflection sideband can be reduced by placing an AR layer on the bottom of the homogeneous layer, and the well-shaped reflection spectrum with near-zero sideband reflection can be achieved by using the double-faced AR design. By merely increasing the thickness of the homogeneous layer with other parameters maintained, the spectrally dense comb-like filters with good unpolarized filtering features can be achieved. The proposed modal analysis can be extended to study the resonant excitation of 2-D periodic nanoarrays with diverse surface profiles.

Music therapy as a non-pharmacological treatment for epilepsy.

PubMed

Liao, Huan; Jiang, Guohui; Wang, Xuefeng

2015-01-01

Epilepsy is one of the most common neurological diseases. Currently, the primary methods of treatment include pharmacological and surgical treatment. However, approximately one-third of patients exhibit refractory epilepsy. Therefore, a novel approach to epilepsy treatment is necessary. Several studies have confirmed that music therapy can be effective at reducing seizures and epileptiform discharges, thus providing a new option for clinicians in the treatment of epilepsy. Although the underlying mechanism of music therapy is unknown, it may be related to resonance, mirror neurons, dopamine pathways and parasympathetic activation. Large sample, multicenter, randomized double-blind and more effectively designed studies are needed for future music therapy studies.

IR-IR Conformation Specific Spectroscopy of Na+(Glucose) Adducts

NASA Astrophysics Data System (ADS)

Voss, Jonathan M.; Kregel, Steven J.; Fischer, Kaitlyn C.; Garand, Etienne

2018-01-01

We report an IR-IR double resonance study of the structural landscape present in the Na+(glucose) complex. Our experimental approach involves minimal modifications to a typical IR predissociation setup, and can be carried out via ion-dip or isomer-burning methods, providing additional flexibility to suit different experimental needs. In the current study, the single-laser IR predissociation spectrum of Na+(glucose), which clearly indicates contributions from multiple structures, was experimentally disentangled to reveal the presence of three α-conformers and five β-conformers. Comparisons with calculations show that these eight conformations correspond to the lowest energy gas-phase structures with distinctive Na+ coordination. [Figure not available: see fulltext.

Sensitivity and Specificity of Double-Track Sign in the Detection of Transverse Sinus Stenosis: A Multicenter Retrospective Study

PubMed Central

Zhu, De-Sheng; Fu, Jue; Zhang, Yi; Xie, Chong; Wang, Xiao-Qing; Zhang, Yue; Yang, Jie; Li, Shi-Xu; Liu, Xiao-Bei; Wan, Zhi-Wen; Dong, Qiang; Guan, Yang-Tai

2015-01-01

Background Transverse sinus stenosis (TSS) is common among patients with cerebral venous sinus thrombosis. No previous studies have reported on double-track sign detected on axial Gd-enhanced T1WI in TSS. This study aimed to determine the sensitivity and specificity of the double-track sign in the detection of TSS. Methods We retrospectively reviewed medical records of 383 patients with transverse sinus thrombosis (TST) and 30 patients with normal transverse sinus from 5 participating hospitals in china from January 2008 to June 2014. 167 feasible transverse sinuses included in this study were categorized into TSS (n = 76), transverse sinus occlusion (TSO) (n = 52) and transverse sinus normal (TSN) groups (n = 39) according to imaging diagnosis on digital subtraction angiography (DSA) or magnetic resonance venography (MRV). Double-track sign on axial Gd-enhanced T1WI was compared among the three groups. Sensitivity and specificity of double-track sign in detection of TSS were calculated, with final imaging diagnosis of TSS on DSA or MRV as the reference standard. Results Of 383 patients with TST recruited over a 6.5-year period, 128 patients were enrolled in the study, 255 patients were excluded because of insufficient clinical data, imaging finding and delay time, and 30 matched patients with normal transverse sinus were enrolled in the control group. Therefore, double-track sign assessment was conducted in 167 available transverse sinuses of 158 patients. Of the 76 sinuses in TSS group, 51 had double-track sign. Of the other 91 sinuses in TSO and TSN groups, 3 had a false-positive double-track sign. Thus, double-track sign on axial Gd-enhanced T1WI was 67.1% (95% CI 55.3–77.2) sensitive and 96.7% (95% CI 89.9–99.1) specific for detection of TSS. Conclusions The double-track sign on axial Gd-enhanced T1WI is highly specific and moderate sensitive for detection of TSS. Nevertheless, it could be a direct sign and might provide an early clue for TSS. PMID:26291452

DOE Office of Scientific and Technical Information (OSTI.GOV)

AlKhaldi, Mashaal Q.; Wehlitz, Ralf, E-mail: rwehlitz@gmail.com

We have experimentally investigated the double-photoionization process in C{sub 6}BrF{sub 5} using monochromatized synchrotron radiation. We compare our results with previously published data for partially deuterated benzene (C{sub 6}H{sub 3}D{sub 3}) over a wide range of photon energies from threshold to 270 eV. A broad resonance in the ratio of doubly to singly charged parent ions at about 65 eV appears shifted in energy compared to benzene data. This shift is due to the difference in the bond lengths in two molecules. A simple model can explain the shape of this resonance. At higher photon energies, we observe another broadmore » resonance that can be explained as a second harmonic of the first resonance.« less

Late Quaternary to Holocene Geology, Geomorphology and Glacial History of Dawson Creek and Surrounding area, Northeast British Columbia, Canada

NASA Astrophysics Data System (ADS)

Henry, Edward Trowbridge

Semiconductor quantum dots in silicon demonstrate exceptionally long spin lifetimes as qubits and are therefore promising candidates for quantum information processing. However, control and readout techniques for these devices have thus far employed low frequency electrons, in contrast to high speed temperature readout techniques used in other qubit architectures, and coupling between multiple quantum dot qubits has not been satisfactorily addressed. This dissertation presents the design and characterization of a semiconductor charge qubit based on double quantum dot in silicon with an integrated microwave resonator for control and readout. The 6 GHz resonator is designed to achieve strong coupling with the quantum dot qubit, allowing the use of circuit QED control and readout techniques which have not previously been applicable to semiconductor qubits. To achieve this coupling, this document demonstrates successful operation of a novel silicon double quantum dot design with a single active metallic layer and a coplanar stripline resonator with a bias tee for dc excitation. Experiments presented here demonstrate quantum localization and measurement of both electrons on the quantum dot and photons in the resonator. Further, it is shown that the resonator-qubit coupling in these devices is sufficient to reach the strong coupling regime of circuit QED. The details of a measurement setup capable of performing simultaneous low noise measurements of the resonator and quantum dot structure are also presented here. The ultimate aim of this research is to integrate the long coherence times observed in electron spins in silicon with the sophisticated readout architectures available in circuit QED based quantum information systems. This would allow superconducting qubits to be coupled directly to semiconductor qubits to create hybrid quantum systems with separate quantum memory and processing components.

Subharmonic generation, chaos, and subharmonic resurrection in an acoustically driven fluid-filled cavity.

PubMed

Cantrell, John H; Adler, Laszlo; Yost, William T

2015-02-01

Traveling wave solutions of the nonlinear acoustic wave equation are obtained for the fundamental and second harmonic resonances of a fluid-filled cavity. The solutions lead to the development of a non-autonomous toy model for cavity oscillations. Application of the Melnikov method to the model equation predicts homoclinic bifurcation of the Smale horseshoe type leading to a cascade of period doublings with increasing drive displacement amplitude culminating in chaos. The threshold value of the drive displacement amplitude at tangency is obtained in terms of the acoustic drive frequency and fluid attenuation coefficient. The model prediction of subharmonic generation leading to chaos is validated from acousto-optic diffraction measurements in a water-filled cavity using a 5 MHz acoustic drive frequency and from the measured frequency spectrum in the bifurcation cascade regime. The calculated resonant threshold amplitude of 0.2 nm for tangency is consistent with values estimated for the experimental set-up. Experimental evidence for the appearance of a stable subharmonic beyond chaos is reported.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rout, Dipak; Vijaya, R.; Centre for Lasers and Photonics, Indian Institute of Technology Kanpur, Kanpur 208016

Well-ordered opaline photonic crystals are grown by inward growing self-assembly method from Rhodamine B dye-doped polystyrene colloids. Subsequent to self-assembly, the crystals are infiltrated with gold nanoparticles of 40 nm diameter. Measurements of the stopband features and photoluminescence intensity from these crystals are supplemented by fluorescence decay time analysis. The fluorescence decay times from the dye-doped photonic crystals before and after the infiltration are dramatically different from each other. A lowered fluorescence decay time was observed for the case of gold infiltrated crystal along with an enhanced emission intensity. Double-exponential decay nature of the fluorescence from the dye-doped crystal gets convertedmore » into single-exponential decay upon the infiltration of gold nanoparticles due to the resonant radiative process resulting from the overlap of the surface plasmon resonance with the emission spectrum. The influence of localized surface plasmon due to gold nanoparticles on the increase in emission intensity and decrease in decay time of the emitters is established.« less

Structure and dynamics of spin-labeled insulin entrapped in a silica matrix by the sol-gel method.

PubMed

Vanea, E; Gruian, C; Rickert, C; Steinhoff, H-J; Simon, V

2013-08-12

The structure and conformational dynamics of insulin entrapped into a silica matrix was monitored during the sol to maturated-gel transition by electron paramagnetic resonance (EPR) spectroscopy. Insulin was successfully spin-labeled with iodoacetamide and the bifunctional nitroxide reagent HO-1944. Room temperature continuous wave (cw) EPR spectra of insulin were recorded to assess the mobility of the attached spin labels. Insulin conformation and its distribution within the silica matrix were studied using double electron-electron resonance (DEER) and low-temperature cw-EPR. A porous oxide matrix seems to form around insulin molecules with pore diameters in the order of a few nanometers. Secondary structure of the encapsulated insulin investigated by Fourier transform infrared spectroscopy proved a high structural integrity of insulin even in the dried silica matrix. The results show that silica encapsulation can be used as a powerful tool to effectively isolate and functionally preserve biomolecules during preparation, storage, and release.

Lipophilic oligonucleotides spontaneously insert into lipid membranes, bind complementary DNA strands, and sequester into lipid-disordered domains.

PubMed

Bunge, Andreas; Kurz, Anke; Windeck, Anne-Kathrin; Korte, Thomas; Flasche, Wolfgang; Liebscher, Jürgen; Herrmann, Andreas; Huster, Daniel

2007-04-10

For the development of surface functionalized bilayers, we have synthesized lipophilic oligonucleotides to combine the molecular recognition mechanism of nucleic acids and the self-assembly characteristics of lipids in planar membranes. A lipophilic oligonucleotide consisting of 21 thymidine units and two lipophilic nucleotides with an alpha-tocopherol moiety as a lipophilic anchor was synthesized using solid-phase methods with a phosphoramadite strategy. The interaction of the water soluble lipophilic oligonucleotide with vesicular lipid membranes and its capability to bind complementary DNA strands was studied using complementary methods such as NMR, EPR, DSC, fluorescence spectroscopy, and fluorescence microscopy. This oligonucleotide inserted stably into preformed membranes from the aqueous phase. Thereby, no significant perturbation of the lipid bilayer and its stability was observed. However, the non-lipidated end of the oligonucleotide is exposed to the aqueous environment, is relatively mobile, and is free to interact with complementary DNA strands. Binding of the complementary single-stranded DNA molecules is fast and accomplished by the formation of Watson-Crick base pairs, which was confirmed by 1H NMR chemical shift analysis and fluorescence resonance energy transfer. The molecular structure of the membrane bound DNA double helix is very similar to the free double-stranded DNA. Further, the membrane bound DNA double strands also undergo regular melting. Finally, in raft-like membrane mixtures, the lipophilic oligonucleotide was shown to preferentially sequester into liquid-disordered membrane domains.

Molecular characterization and comparison of shale oils generated by different pyrolysis methods using FT-ICR mass spectrometry

USGS Publications Warehouse

Jin, J.M.; Kim, S.; Birdwell, J.E.

2011-01-01

Fourier transform ion cyclotron resonance mass spectrometry (FT ICR-MS) was applied in the analysis of shale oils generated using two different pyrolysis systems under laboratory conditions meant to simulate surface and in situ oil shale retorting. Significant variations were observed in the shale oils, particularly the degree of conjugation of the constituent molecules. Comparison of FT ICR-MS results to standard oil characterization methods (API gravity, SARA fractionation, gas chromatography-flame ionization detection) indicated correspondence between the average Double Bond Equivalence (DBE) and asphaltene content. The results show that, based on the average DBE values and DBE distributions of the shale oils examined, highly conjugated species are enriched in samples produced under low pressure, high temperature conditions and in the presence of water.

Design and performance analysis of a rotary traveling wave ultrasonic motor with double vibrators.

PubMed

Dong, Zhaopeng; Yang, Ming; Chen, Zhangqi; Xu, Liang; Meng, Fan; Ou, Wenchu

2016-09-01

This paper presents the development of a rotary traveling wave ultrasonic motor, in which a vibrating stator and vibrating rotor are combined in one motor. The stator and rotor are designed as similar structures an elastic body and a piezoelectric ceramic ring. In exciting of the piezoelectric ceramics, the elastic body of the stator and rotor will generate respective traveling waves, which force each other forward in the contact zone. Based on the elliptical rule of particle motion and matching principle of vibration, the design rules of two vibrators are determined. The finite element method is used to design the sizes of vibrators to ensure that they operate in resonance, and the simulation is verified by measuring the vibration with an impedance analyzer. It is found out that to maintain an appropriate contact between the stator and rotor, two vibrators need to be designed with close resonance frequencies, different vibration amplitudes, and be driven by an identical driving frequency. To analyze this innovative contact mechanism, particle velocity synthesis theory and contact force analysis using Hertz contact model are carried out. Finally, a prototype is fabricated and tested to verify the theoretical results. The test results show that the output performance of the motor driven by the two vibrators is significantly improved compared to the motor driven by a sole stator or rotor, which confirms the validity of the double-vibrator motor concept. Copyright © 2016 Elsevier B.V. All rights reserved.

‘Double cortex’ sign on FDG-PET/CT in diffuse band heterotopia

PubMed Central

Tripathi, Madhavi; Tripathi, Manjari; Kumar, Ganesh; Malhotra, Arun; Bal, Chandra Sekhar

2013-01-01

F-18 Fluorodeoxyglucose (FDG) Positron emission tomography/Computed Tomography (PET/CT) has come to play an increasingly important role for the pre-surgical evaluation of drug resistant epilepsy and complements Magnetic Resonance Imaging (MRI) in the evaluation of grey matter heterotopias. This case illustrates the characteristic pattern of metabolic abnormality in diffuse band heterotopia (DBH) which is otherwise called double cortex syndrome. The presence of metabolic activity in the heterotopic inner cortical band and in the overlying true cortex gives rise to the ‘double cortex’ sign on FDG-PET, concurrent CT provides a good anato-metabolic coregistration. PMID:24379541

Pulsed optical-optical double resonnance spectroscopy of A 1Σ +g state of 7Li 2

NASA Astrophysics Data System (ADS)

Bernheim, R. A.; Gold, L. P.; Kelly, P. B.; Kittrell, C.; Veirs, D. K.

1980-02-01

Optical-optical double resonance using two nitrogen-laser pumped dye lasers has been used to make the first study of an excited 1σ +g state of 7Li 2. Preliminary molecular constants in cm -1 are Te = 29972, Y10 = 227, Y20 = -1.92, Y01 = 0390, Y02 = -4.3 × 10 -6and Y11 = -1.4 × 10 -3,with re = 0. 351 nm.

Emission wavelength tuning of fluorescence by fine structural control of optical metamaterials with Fano resonance

PubMed Central

Moritake, Y.; Kanamori, Y.; Hane, K.

2016-01-01

We demonstrated fine emission wavelength tuning of quantum dot (QD) fluorescence by fine structural control of optical metamaterials with Fano resonance. An asymmetric-double-bar (ADB), which was composed of only two bars with slightly different bar lengths, was used to obtain Fano resonance in the optical region. By changing the short bar length of ADB structures with high dimensional accuracy in the order of 10 nm, resonant wavelengths of Fano resonance were controlled from 1296 to 1416 nm. Fluorescence of QDs embedded in a polymer layer on ADB metamaterials were modified due to coupling to Fano resonance and fine tuning from 1350 to 1376 nm was observed. Wavelength tuning of modified fluorescence was reproduced by analysis using absorption peaks of Fano resonance. Tuning range of modified fluorescence became narrow, which was interpreted by a simple Gaussian model and resulted from comparable FWHM in QD fluorescence and Fano resonant peaks. The results will help the design and fabrication of metamaterial devices with fluorophores such as light sources and biomarkers. PMID:27622503

Theoretical Studies Relating to the Interaction of Radiation with Matter

DTIC Science & Technology

1989-09-15

and Heisenberg picture calculations of resonance fluorescence in the presence of a strong field. Again, the Schrodinger calculation is quite...discussed in Sec. VIII. numerous effects have been discussed assuming fluctuat- ing radiation fields (resonant fluorescence , double reso- nance, multiphoton...tered at t12 =0. The peak has temporal width It 2 1 = rcl2 and, moreover, for fully correlated pulses (0) = 1) there is FIG. 6. Signal of order n = 1 as a

Efficient single photon detection by quantum dot resonant tunneling diodes.

PubMed

Blakesley, J C; See, P; Shields, A J; Kardynał, B E; Atkinson, P; Farrer, I; Ritchie, D A

2005-02-18

We demonstrate that the resonant tunnel current through a double-barrier structure is sensitive to the capture of single photoexcited holes by an adjacent layer of quantum dots. This phenomenon could allow the detection of single photons with low dark count rates and high quantum efficiencies. The magnitude of the sensing current may be controlled via the thickness of the tunnel barriers. Larger currents give improved signal to noise and allow sub-mus photon time resolution.

Oscillations up to 712 GHz in InAs/AlSb resonant-tunneling diodes

NASA Technical Reports Server (NTRS)

Brown, E. R.; Parker, C. D.; Mahoney, L. J.; Molvar, K. M.; Soderstrom, J. R.

1991-01-01

Oscillations have been obtained at frequencies from 100 to 712 GHz in InAs/AlSb double-barrier resonant-tunneling diodes at room temperature. The measured power density at 360 GHz was 90 W/sq cm, which is 50 times that generated by GaAs/AlAs diodes at essentially the same frequency. The oscillation at 712 GHz represents the highest frequency reported to date from a solid-state electronic oscillator at room temperature.

Efficient second harmonic generation of a diode-laser-pumped CW Nd:YAG laser using monolithic MgO:LiNbO3 external resonant cavities

NASA Technical Reports Server (NTRS)

Kozlovsky, William J.; Nabors, C. D.; Byer, Robert L.

1988-01-01

56-percent efficient external-cavity-resonant second-harmonic generation of a diode-laser pumped, CW single-axial-mode Nd:YAG laser is reported. A theory of external doubling with a resonant fundamental is presented and compared to experimental results for three monolithic cavities of nonlinear MgO:LiNbO3. The best conversion efficiency was obtained with a 12.5-mm-long monolithic ring cavity doubler, which produced 29.7 mW of CW, single-axial model 532-nm radiation from an input of 52.5 mW.

Single-frequency diode-pumped lasers for free-space optical communication

NASA Technical Reports Server (NTRS)

Kane, Thomas J.; Cheng, Emily A. P.; Gerstenberger, David C.; Wallace, Richard W.

1990-01-01

Recent advances in laser technology for intersatellite optical communication systems are reviewed and illustrated with graphs and diagrams. Topics addressed include (1) single-frequency diode-pumped Nd:YAG lasers of monolithic ring configuration (yielding 368-384 mW output power with 1-W pumping), (2) injection chaining of up to 10 monolithic resonators to achieve redundancy and/or higher output power, (3) 2-kHz-linewidth 5-mW versions of (1) which are tunable over a 30-MHz range for use as local oscillators in coherent communication, (4) resonant external modulation and doubling or resonant phase modulation of diode-pumped lasers, and (5) wavelength multiplexing.

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

NASA Astrophysics Data System (ADS)

Schooneveld, E. M.; Mayers, J.; Rhodes, N. J.; Pietropaolo, A.; Andreani, C.; Senesi, R.; Gorini, G.; Perelli-Cippo, E.; Tardocchi, M.

2006-09-01

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

Room-temperature coupling between electrical current and nuclear spins in OLEDs

NASA Astrophysics Data System (ADS)

Malissa, H.; Kavand, M.; Waters, D. P.; van Schooten, K. J.; Burn, P. L.; Vardeny, Z. V.; Saam, B.; Lupton, J. M.; Boehme, C.

2014-09-01

The effects of external magnetic fields on the electrical conductivity of organic semiconductors have been attributed to hyperfine coupling of the spins of the charge carriers and hydrogen nuclei. We studied this coupling directly by implementation of pulsed electrically detected nuclear magnetic resonance spectroscopy in organic light-emitting diodes (OLEDs). The data revealed a fingerprint of the isotope (protium or deuterium) involved in the coherent spin precession observed in spin-echo envelope modulation. Furthermore, resonant control of the electric current by nuclear spin orientation was achieved with radiofrequency pulses in a double-resonance scheme, implying current control on energy scales one-millionth the magnitude of the thermal energy.

Reduction of the coupling vibration between the bending vibrators of the frequency-change-type two-axis acceleration sensor

NASA Astrophysics Data System (ADS)

Sugawara, Sumio; Sasaki, Yoshifumi; Kudo, Subaru

2018-07-01

The frequency-change-type two-axis acceleration sensor uses a cross-type vibrator consisting of four bending vibrators. When coupling vibration exists between these four bending vibrators, the resonance frequency of each vibrator cannot be adjusted independently. In this study, methods of reducing the coupling vibration were investigated by finite-element analysis. A method of adjusting the length of the short arm of each vibrator was proposed for reducing the vibration. When piezoelectric ceramics were bonded to the single-sided surface of the vibrator, the method was not sufficient. Thus, the ceramics with the same dimensions were bonded to double-sided surfaces. As a result, a marked reduction was obtained in this case. Also, the linearity of the sensor characteristics was significantly improved in a small acceleration range. Accordingly, it was clarified that considering the symmetry along the thickness direction of the vibrator is very important.

Er:YAG laser technology for remote sensing applications

NASA Astrophysics Data System (ADS)

Chen, Moran; Burns, Patrick M.; Litvinovitch, Viatcheslav; Storm, Mark; Sawruk, Nicholas W.

2016-10-01

Fibertek has developed an injection locked, resonantly pumped Er:YAG solid-state laser operating at 1.6 μm capable of pulse repetition rates of 1 kHz to 10 kHz for airborne methane and water differential absorption lidars. The laser is resonantly pumped with a fiber-coupled 1532 nm diode laser minimizing the quantum defect and thermal loading generating tunable single-frequency output of 1645-1646 nm with a linewidth of < 100 MHz. The frequency-doubled 1.6 μm Er:YAG laser emits wavelengths in the 822-823 nm spectrum, coincident with water vapor lines. Various cavity designs were studied and optimized for compactness and performance, with the optimal design being an injection seeded and locked five-mirror ring cavity. The laser generated 4 W of average power at pulse repetition frequencies (PRFs) of 1 kHz and 10 kHz, corresponding to 4 mJ and 400 μJ pulse energies, respectively. The 1645 nm was subsequently frequency doubled to 822.5 nm with a 600 pm tuning range covering multiple water absorption lines, with a pulse energy of 1 mJ and a pulse repetition frequency of 1 kHz. The resonator cavity was locked to the seed wavelength via a Pound Drever Hall (PDH) technique and an analog Proportional Integral Derivative (PID) Controller driving a high-bandwidth piezoelectric (PZT)-mounted cavity mirror. Two seed sources lasing on and off the methane absorption line were optically switched to tune the resonator wavelength on and off the methane absorption line between each sequential output pulse. The cavity locking servo maintained the cavity resonance for each pulse.

Electron spin resonance and spin-valley physics in a silicon double quantum dot.

PubMed

Hao, Xiaojie; Ruskov, Rusko; Xiao, Ming; Tahan, Charles; Jiang, HongWen

2014-05-14

Silicon quantum dots are a leading approach for solid-state quantum bits. However, developing this technology is complicated by the multi-valley nature of silicon. Here we observe transport of individual electrons in a silicon CMOS-based double quantum dot under electron spin resonance. An anticrossing of the driven dot energy levels is observed when the Zeeman and valley splittings coincide. A detected anticrossing splitting of 60 MHz is interpreted as a direct measure of spin and valley mixing, facilitated by spin-orbit interaction in the presence of non-ideal interfaces. A lower bound of spin dephasing time of 63 ns is extracted. We also describe a possible experimental evidence of an unconventional spin-valley blockade, despite the assumption of non-ideal interfaces. This understanding of silicon spin-valley physics should enable better control and read-out techniques for the spin qubits in an all CMOS silicon approach.

Proton electron nuclear double resonance from nitrosyl horse heart myoglobin: the role of His-E7 and Val-E11.

PubMed Central

Flores, M; Wajnberg, E; Bemski, G

2000-01-01

Electron nuclear double resonance (ENDOR) spectroscopy has been used to study protons in nitrosyl horse heart myoglobin (MbNO). (1)H ENDOR spectra were recorded for different settings of the magnetic field. Detailed analysis of the ENDOR powder spectra, using computer simulation, based on the "orientation-selection" principle, leads to the identification of the available protons in the heme pocket. We observe hyperfine interactions of the N(HisF8)-Fe(2+)-N(NO) complex with five protons in axial and with eight protons in the rhombic symmetry along different orientations, including those of the principal axes of the g-tensor. Protons from His-E7 and Val-E11 residues are identified in the two symmetries, rhombic and axial, exhibited by MbNO. Our results indicate that both residues are present inside the heme pocket and help to stabilize one particular conformation. PMID:10733988

Pulsed electron nuclear double resonance studies of the photoexcited triplet state of pentacene in p-terphenyl crystals at room temperature.

PubMed

Yago, Tomoaki; Link, Gerhard; Kothe, Gerd; Lin, Tien-Sung

2007-09-21

Pulsed electron nuclear double resonance (ENDOR) using a modified Davies-type [Phys. Lett. 47A, 1 (1974)] sequence is employed to study the hyperfine (HF) structure of the photoexcited triplet state of pentacene dispersed in protonated and deuterated p-terphenyl single crystals. The strong electron spin polarization and long phase memory time of triplet pentacene enable us to perform the ENDOR measurements on the S=1 spin system at room temperature. Proton HF tensor elements and spin density values of triplet pentacene are extracted from a detailed angular-dependent study in which the orientation of the magnetic field is varied systematically in two different pentacene planes. Analysis reveals that the pentacene molecule is no longer planar in the p-terphenyl host lattice. The distortion is more pronounced in the deuterated crystal where the unit cell dimensions are slightly smaller than those of the protonated crystal.

Resonance spiking by periodic loss in the double-sided liquid cooling disk oscillator

NASA Astrophysics Data System (ADS)

Nie, Rongzhi; She, Jiangbo; Li, Dongdong; Li, Fuli; Peng, Bo

2017-03-01

A double-sided liquid cooling Nd:YAG disk oscillator working at a pump repetition rate of 20 Hz is demonstrated. The output energy of 376 mJ is realized, corresponding to the optical-optical efficiency of 12.8% and the slope efficiency of 14%. The pump pulse width is 300 µs and the laser pulse width is 260 µs. Instead of being a damped signal, the output of laser comprises undamped spikes. A periodic intra-cavity loss was found by numerical analysis, which has a frequency component near the eigen frequency of the relaxation oscillation. Resonance effect will induce amplified spikes even though the loss fluctuates in a small range. The Shark-Hartmann sensor was used to investigate the wavefront aberration induced by turbulent flow and temperature gradient. According to the wavefront and fluid mechanics analysis, it is considered that the periodic intra-cavity loss can be attributed to turbulent flow and temperature gradient.

Double negative acoustic metastructure for attenuation of acoustic emissions

NASA Astrophysics Data System (ADS)

Kumar, Sanjay; Bhushan, Pulak; Prakash, Om; Bhattacharya, Shantanu

2018-03-01

Acoustic metamaterials hold great potential for attenuation of low frequency acoustic emissions. However, a fundamental challenge is achieving high transmission loss over a broad frequency range. In this work, we report a double negative acoustic metastructure for absorption of low frequency acoustic emissions in an aircraft. This is achieved by utilizing a periodic array of hexagonal cells interconnected with a neck and mounted with an elastic membrane on both ends. An average transmission loss of 56 dB under 500 Hz and an overall absorption of over 48% have been realized experimentally. The negative mass density is derived from the dipolar resonances created as a result of the in-phase movement of the membranes. Further, the negative bulk modulus is ascribed to the combined effect of out-of-phase acceleration of the membranes and the Helmholtz resonator. The proposed metastructure enables absorption of low frequency acoustic emissions with improved functionality that is highly desirable for varied applications.

Recoil polarization and beam-recoil double polarization measurement of eta electroproduction on the proton in the region of the S11(1535) resonance.

PubMed

Merkel, H; Achenbach, P; Ayerbe Gayoso, C; Bernauer, J C; Böhm, R; Bosnar, D; Cheymol, B; Distler, M O; Doria, L; Fonvieille, H; Friedrich, J; Janssens, P; Makek, M; Müller, U; Nungesser, L; Pochodzalla, J; Potokar, M; Sánchez Majos, S; Schlimme, B S; Sirca, S; Tiator, L; Walcher, Th; Weinriefer, M

2007-09-28

The beam-recoil double polarization P(x')(h) and P(z')(h) and the recoil polarization P(y') were measured for the first time for the p(e,e'p)eta reaction at a four-momentum transfer of Q(2) = 0.1 GeV(2)/c(2) and a center of mass production angle of theta = 120 degrees at the Mainz Microtron MAMI-C. With a center of mass energy range of 1500 MeV

Coexistence of superconductivity and short-range double-stripe spin correlations in Te-vapor annealed FeTe 1–xSe x with x ≤ 0.2

DOE PAGES

Xu, Zhijun; Tranquada, John M.; Schneeloch, J. A.; ...

2018-06-30

In as-grown bulk crystals of Fe 1+yTe 1–xSe x with x ≲ 0.3, excess Fe (y > 0) is inevitable and correlates with a suppression of superconductivity. At the same time, t here remains the question as to whether the character of the antiferromagnetic correlations associated wi th the enhanced anion height above the Fe planes in Te-rich samples is compatible with superconductivity. To t est this, we have annealed as-grown crystals with x = 0.1 and 0.2 in Te vapor, effectively reducing the excess Fe and in ducing bulk superconductivity. Inelastic neutron scattering measurements reveal low-energy magnet ic excitationsmore » consistent with short-range correlations of the double-stripe type; nevertheless, cooling int o the superconducting state results in a spin gap and a spin resonance, with the extra signal in the resonance being short-range with a mixed single-stripe/double-stripe character, which is different than other iron-based superconductors. In conclusion, the mixed magnetic character of these superconducting samples does not appear to be trivially explainable by inhomogeneity.« less

Design and Fabrication of 1D and 2D Micro Scanners Actuated by Double Layered Lead Zirconate Titanate (PZT) Bimorph Beams

NASA Astrophysics Data System (ADS)

Tsaur, Jiunnjye; Zhang, Lulu; Maeda, Ryutaro; Matsumoto, Sohei; Khumpuang, Sommawan

2002-06-01

Micro scanners including 1D scanner beams and 2D scanning micromirrors are designed and fabricated. In order to yield large bending force, the sol-gel derived double layered lead zirconate titanate (PZT) structures are developed to be the actuator components. In our developed fabrication process, the use of thermal treatment and the addition of one platinium/titanium film played an important role to yield the well-crystallized perovskite phase and decrease the residual strss of total cantilever structures successfully. In the case of 1D scanner beams with the size of 750× 230 μm2, the optical scanning angle was 41.2 deg with respect to actuation with AC 5 V at 2706 Hz. Under the applied bias of 10 V, the bimorph beam bended upward and the deflection angle of 34.3 deg was measured. A 2D scanning micromirror supported by four suspended double layered PZT actuators was designed to rotate around two orthogonal axes by the operation at different resonant frequencies. While resonating with AC 7.5 V at 3750 Hz and 5350 Hz, the maximum scanning area of 24\\circ× 26\\circ was obtained.

Coexistence of superconductivity and short-range double-stripe spin correlations in Te-vapor annealed FeTe 1–xSe x with x ≤ 0.2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Zhijun; Tranquada, John M.; Schneeloch, J. A.

In as-grown bulk crystals of Fe 1+yTe 1–xSe x with x ≲ 0.3, excess Fe (y > 0) is inevitable and correlates with a suppression of superconductivity. At the same time, t here remains the question as to whether the character of the antiferromagnetic correlations associated wi th the enhanced anion height above the Fe planes in Te-rich samples is compatible with superconductivity. To t est this, we have annealed as-grown crystals with x = 0.1 and 0.2 in Te vapor, effectively reducing the excess Fe and in ducing bulk superconductivity. Inelastic neutron scattering measurements reveal low-energy magnet ic excitationsmore » consistent with short-range correlations of the double-stripe type; nevertheless, cooling int o the superconducting state results in a spin gap and a spin resonance, with the extra signal in the resonance being short-range with a mixed single-stripe/double-stripe character, which is different than other iron-based superconductors. In conclusion, the mixed magnetic character of these superconducting samples does not appear to be trivially explainable by inhomogeneity.« less

Nested trampoline resonators for optomechanics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weaver, M. J., E-mail: mweaver@physics.ucsb.edu; Pepper, B.; Luna, F.

2016-01-18

Two major challenges in the development of optomechanical devices are achieving a low mechanical and optical loss rate and vibration isolation from the environment. We address both issues by fabricating trampoline resonators made from low pressure chemical vapor deposition Si{sub 3}N{sub 4} with a distributed Bragg reflector mirror. We design a nested double resonator structure with 80 dB of mechanical isolation from the mounting surface at the inner resonator frequency, and we demonstrate up to 45 dB of isolation at lower frequencies in agreement with the design. We reliably fabricate devices with mechanical quality factors of around 400 000 at room temperature. Inmore » addition, these devices were used to form optical cavities with finesse up to 181 000 ± 1000. These promising parameters will enable experiments in the quantum regime with macroscopic mechanical resonators.« less

Non-Gaussian, non-dynamical stochastic resonance

NASA Astrophysics Data System (ADS)

Szczepaniec, Krzysztof; Dybiec, Bartłomiej

2013-11-01

The classical model revealing stochastic resonance is a motion of an overdamped particle in a double-well fourth order potential when combined action of noise and external periodic driving results in amplifying of weak signals. Resonance behavior can also be observed in non-dynamical systems. The simplest example is a threshold triggered device. It consists of a periodic modulated input and noise. Every time an output crosses the threshold the signal is recorded. Such a digitally filtered signal is sensitive to the noise intensity. There exists the optimal value of the noise intensity resulting in the "most" periodic output. Here, we explore properties of the non-dynamical stochastic resonance in non-equilibrium situations, i.e. when the Gaussian noise is replaced by an α-stable noise. We demonstrate that non-equilibrium α-stable noises, depending on noise parameters, can either weaken or enhance the non-dynamical stochastic resonance.

A polygonal double-layer coil design for high-efficiency wireless power transfer

NASA Astrophysics Data System (ADS)

Mao, Shitong; Wang, Hao; Mao, Zhi-Hong; Sun, Mingui

2018-05-01

In this work, we present a novel coil structure for the design of Wireless Power Transfer (WPT) systems via magnetic resonant coupling. The new coil consists of two layers of flat polygonal windings in square, pentagonal and hexagonal shapes. The double-layer coil can be conveniently fabricated using the print circuit broad (PCB) technology. In our design, we include an angle between the two layers which can be adjusted to change the area of inter-layer overlap. This unique structure is thoroughly investigated with respect to the quality factor Q and the power transfer efficiency (PTE) using the finite element method (FEM). An equivalent circuit is derived and used to explain the properties of the angularly shifted double-layer coil theoretically. Comparative experiments are conducted from which the performance of the new coil is evaluated quantitatively. Our results have shown that an increased shift angle improves the Q-factor, and the optimal PTE is achieved when the angle reaches the maximum. When compared to the pentagonal and hexagonal coils, the square coil achieves the highest PTE due to its lowest parasitic capacitive effects. In summary, our new coil design improves the performance of WPT systems and allows a formal design procedure for optimization in a given application.

Design and prototyping of HL-LHC double quarter wave crab cavities for SPS test

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verdu-Andres, S.; Skaritka, J.; Wu, Q.

2015-05-03

The LHC high luminosity project envisages the use of the crabbing technique for increasing and levelling the LHC luminosity. Double Quarter Wave (DQW) resonators are compact cavities especially designed to meet the technical and performance requirements for LHC beam crabbing. Two DQW crab cavities are under fabrication and will be tested with beam in the Super Proton Synchrotron (SPS) at CERN by 2017. This paper describes the design and prototyping of the DQW crab cavities for the SPS test.

Chemically Doped Double-Walled Carbon Nanotubes: Cylindrical Molecular Capacitors

NASA Astrophysics Data System (ADS)

Chen, Gugang; Bandow, S.; Margine, E. R.; Nisoli, C.; Kolmogorov, A. N.; Crespi, Vincent H.; Gupta, R.; Sumanasekera, G. U.; Iijima, S.; Eklund, P. C.

2003-06-01

A double-walled carbon nanotube is used to study the radial charge distribution on the positive inner electrode of a cylindrical molecular capacitor. The outer electrode is a shell of bromine anions. Resonant Raman scattering from phonons on each carbon shell reveals the radial charge distribution. A self-consistent tight-binding model confirms the observed molecular Faraday cage effect, i.e., most of the charge resides on the outer wall, even when this wall was originally semiconducting and the inner wall was metallic.

Chemically doped double-walled carbon nanotubes: cylindrical molecular capacitors.

PubMed

Chen, Gugang; Bandow, S; Margine, E R; Nisoli, C; Kolmogorov, A N; Crespi, Vincent H; Gupta, R; Sumanasekera, G U; Iijima, S; Eklund, P C

2003-06-27

A double-walled carbon nanotube is used to study the radial charge distribution on the positive inner electrode of a cylindrical molecular capacitor. The outer electrode is a shell of bromine anions. Resonant Raman scattering from phonons on each carbon shell reveals the radial charge distribution. A self-consistent tight-binding model confirms the observed molecular Faraday cage effect, i.e., most of the charge resides on the outer wall, even when this wall was originally semiconducting and the inner wall was metallic.

Multi-frequency spin manipulation using rapidly tunable superconducting coplanar waveguide microresonators

DOE PAGES

Asfaw, A. T.; Sigillito, A. J.; Tyryshkin, A. M.; ...

2017-07-17

In this work, we demonstrate the use of frequency-tunable superconducting NbTiN coplanar waveguide microresonators for multi-frequency pulsed electron spin resonance (ESR) experiments. By applying a bias current to the center pin, the resonance frequency (~7.6 GHz) can be continuously tuned by as much as 95 MHz in 270 ns without a change in the quality factor of 3000 at 2 K. We demonstrate the ESR performance of our resonators by measuring donor spin ensembles in silicon and show that adiabatic pulses can be used to overcome magnetic field inhomogeneities and microwave power limitations due to the applied bias current. Wemore » take advantage of the rapid tunability of these resonators to manipulate both phosphorus and arsenic spins in a single pulse sequence, demonstrating pulsed double electron-electron resonance. Our NbTiN resonator design is useful for multi-frequency pulsed ESR and should also have applications in experiments where spin ensembles are used as quantum memories.« less

Multi-frequency spin manipulation using rapidly tunable superconducting coplanar waveguide microresonators

NASA Astrophysics Data System (ADS)

Asfaw, A. T.; Sigillito, A. J.; Tyryshkin, A. M.; Schenkel, T.; Lyon, S. A.

2017-07-01

In this work, we demonstrate the use of frequency-tunable superconducting NbTiN coplanar waveguide microresonators for multi-frequency pulsed electron spin resonance (ESR) experiments. By applying a bias current to the center pin, the resonance frequency (˜7.6 GHz) can be continuously tuned by as much as 95 MHz in 270 ns without a change in the quality factor of 3000 at 2 K. We demonstrate the ESR performance of our resonators by measuring donor spin ensembles in silicon and show that adiabatic pulses can be used to overcome magnetic field inhomogeneities and microwave power limitations due to the applied bias current. We take advantage of the rapid tunability of these resonators to manipulate both phosphorus and arsenic spins in a single pulse sequence, demonstrating pulsed double electron-electron resonance. Our NbTiN resonator design is useful for multi-frequency pulsed ESR and should also have applications in experiments where spin ensembles are used as quantum memories.

Randomized Double-Blind Placebo-Controlled Trial of Bevacizumab Therapy for Radiation Necrosis of the Central Nervous System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levin, Victor A., E-mail: vlevin49@comcast.ne; Bidaut, Luc; Hou, Ping

Purpose: To conduct a controlled trial of bevacizumab for the treatment of symptomatic radiation necrosis of the brain. Methods and Materials: A total of 14 patients were entered into a placebo-controlled randomized double-blind study of bevacizumab for the treatment of central nervous system radiation necrosis. All patients were required to have radiographic or biopsy proof of central nervous system radiation necrosis and progressive neurologic symptoms or signs. Eligible patients had undergone irradiation for head-and-neck carcinoma, meningioma, or low- to mid-grade glioma. Patients were randomized to receive intravenous saline or bevacizumab at 3-week intervals. The magnetic resonance imaging findings 3 weeksmore » after the second treatment and clinical signs and symptoms defined the response or progression. Results: The volumes of necrosis estimated on T{sub 2}-weighted fluid-attenuated inversion recovery and T{sub 1}-weighted gadolinium-enhanced magnetic resonance imaging scans demonstrated that although no patient receiving placebo responded (0 of 7), all bevacizumab-treated patients did so (5 of 5 randomized and 7 of 7 crossover) with decreases in T{sub 2}-weighted fluid-attenuated inversion recovery and T{sub 1}-weighted gadolinium-enhanced volumes and a decrease in endothelial transfer constant. All bevacizumab-treated patients-and none of the placebo-treated patients-showed improvement in neurologic symptoms or signs. At a median of 10 months after the last dose of bevacizumab in patients receiving all four study doses, only 2 patients had experienced a recurrence of magnetic resonance imaging changes consistent with progressive radiation necrosis; one patient received a single additional dose of bevacizumab and the other patient received two doses. Conclusion: The Class I evidence of bevacizumab efficacy from the present study in the treatment of central nervous system radiation necrosis justifies consideration of this treatment option for people with radiation necrosis secondary to the treatment of head-and-neck cancer and brain cancer.« less

Increasing sensitivity of pulse EPR experiments using echo train detection schemes.

PubMed

Mentink-Vigier, F; Collauto, A; Feintuch, A; Kaminker, I; Tarle, V; Goldfarb, D

2013-11-01

Modern pulse EPR experiments are routinely used to study the structural features of paramagnetic centers. They are usually performed at low temperatures, where relaxation times are long and polarization is high, to achieve a sufficient Signal/Noise Ratio (SNR). However, when working with samples whose amount and/or concentration are limited, sensitivity becomes an issue and therefore measurements may require a significant accumulation time, up to 12h or more. As the detection scheme of practically all pulse EPR sequences is based on the integration of a spin echo--either primary, stimulated or refocused--a considerable increase in SNR can be obtained by replacing the single echo detection scheme by a train of echoes. All these echoes, generated by Carr-Purcell type sequences, are integrated and summed together to improve the SNR. This scheme is commonly used in NMR and here we demonstrate its applicability to a number of frequently used pulse EPR experiments: Echo-Detected EPR, Davies and Mims ENDOR (Electron-Nuclear Double Resonance), DEER (Electron-Electron Double Resonance|) and EDNMR (Electron-Electron Double Resonance (ELDOR)-Detected NMR), which were combined with a Carr-Purcell-Meiboom-Gill (CPMG) type detection scheme at W-band. By collecting the transient signal and integrating a number of refocused echoes, this detection scheme yielded a 1.6-5 folds SNR improvement, depending on the paramagnetic center and the pulse sequence applied. This improvement is achieved while keeping the experimental time constant and it does not introduce signal distortion. Copyright © 2013 Elsevier Inc. All rights reserved.

Enhanced optical nonlinearities in the near-infrared using III-nitride heterostructures coupled to metamaterials

DOE PAGES

Wolf, Omri; Allerman, Andrew A.; Ma, Xuedan; ...

2015-10-15

We use planar metamaterial resonators to enhance, by more than two orders of magnitude, the optical second harmonic generation, in the near infrared, obtained from intersubband transitions in III-Nitride heterostructures. The improvement arises from two factors: employing an asymmetric double quantum well design and aligning the resonators’ cross-polarized resonances with the intersubband transition energies. The resulting nonlinear metamaterial operates at wavelengths where single photon detection is available, and represents a new class of sources for quantum photonics related phenomena.

Development of a Silicon Metal-Oxide-Semiconductor-Based Qubit Using Spin Exchange Interactions Alone

DTIC Science & Technology

2016-03-31

Electron spin resonance and spin–valley physics in a silicon double quantum dot, Nature Communications, (05 2014): 0. doi: 10.1038/ncomms4860 Ming...new scheme to better manipulate the exchange-only qubit using a pulsed RF source [5], known as a resonant -exchange-qubit [6,7], in GaAs further...triple points into a quadruple point [10], as shown in Fig. 1. We can also gate control the tunnel coupling over a broad energy range. The

Toroidal silicon polarization analyzer for resonant inelastic x-ray scattering

DOE PAGES

Gao, Xuan; Casa, Diego; Kim, Jungho; ...

2016-08-15

Resonant Inelastic X-ray Scattering (RIXS) is a powerful probe for studying electronic excitations in materials. Standard high energy RIXS measurements do not measure the polarization of the scattered x-rays, which is unfortunate since it carries information about the nature and symmetry of the excitations involved in the scattering process. Moreover we report the fabrication of thin Si-based polarization analyzers with a double-concave toroidal surface, useful for L-edge RIXS studies in heavier atoms such as the 5-d transition metals.

Quantum memory on a charge qubit in an optical microresonator

NASA Astrophysics Data System (ADS)

Tsukanov, A. V.

2017-10-01

A quantum-memory unit scheme on the base of a semiconductor structure with quantum dots is proposed. The unit includes a microresonator with single and double quantum dots performing frequencyconverter and charge-qubit functions, respectively. The writing process is carried out in several stages and it is controlled by optical fields of the resonator and laser. It is shown that, to achieve high writing probability, it is necessary to use high-Q resonators and to be able to suppress relaxation processes in quantum dots.

Pores of no return.

PubMed

Andrews, David W

2014-11-20

In this issue, Bleicken et al. (2014) use double electron-electron resonance (DEER) spectroscopy to propose a new model for the active form of Bax at membranes that differs significantly from those previously proposed. Copyright © 2014 Elsevier Inc. All rights reserved.

Deriving Lindblad master equations with Keldysh diagrams: Correlated gain and loss in higher order perturbation theory

NASA Astrophysics Data System (ADS)

Müller, Clemens; Stace, Thomas M.

2017-01-01

Motivated by correlated decay processes producing gain, loss, and lasing in driven semiconductor quantum dots [Phys. Rev. Lett. 113, 036801 (2014), 10.1103/PhysRevLett.113.036801; Science 347, 285 (2015), 10.1126/science.aaa2501; Phys. Rev. Lett. 114, 196802 (2015), 10.1103/PhysRevLett.114.196802], we develop a theoretical technique by using Keldysh diagrammatic perturbation theory to derive a Lindblad master equation that goes beyond the usual second-order perturbation theory. We demonstrate the method on the driven dissipative Rabi model, including terms up to fourth order in the interaction between the qubit and both the resonator and environment. This results in a large class of Lindblad dissipators and associated rates which go beyond the terms that have previously been proposed to describe similar systems. All of the additional terms contribute to the system behavior at the same order of perturbation theory. We then apply these results to analyze the phonon-assisted steady-state gain of a microwave field driving a double quantum dot in a resonator. We show that resonator gain and loss are substantially affected by dephasing-assisted dissipative processes in the quantum-dot system. These additional processes, which go beyond recently proposed polaronic theories, are in good quantitative agreement with experimental observations.

Franck-Condon fingerprinting of vibration-tunneling spectra.

PubMed

Berrios, Eduardo; Sundaradevan, Praveen; Gruebele, Martin

2013-08-15

We introduce Franck-Condon fingerprinting as a method for assigning complex vibration-tunneling spectra. The B̃ state of thiophosgene (SCCl2) serves as our prototype. Despite several attempts, assignment of its excitation spectrum has proved difficult because of near-degenerate vibrational frequencies, Fermi resonance between the C-Cl stretching mode and the Cl-C-Cl bending mode, and large tunneling splittings due to the out-of-plane umbrella mode. Hence, the spectrum has never been fitted to an effective Hamiltonian. Our assignment approach replaces precise frequency information with intensity information, eliminating the need for double resonance spectroscopy or combination differences, neither of which have yielded a full assignment thus far. The dispersed fluorescence spectrum of each unknown vibration-tunneling state images its character onto known vibrational progressions in the ground state. By using this Franck-Condon fingerprint, we were able to determine the predominant character of several vibration-tunneling states and assign them; in other cases, the fingerprinting revealed that the states are strongly mixed and cannot be characterized with a simple normal mode assignment. The assigned transitions from vibration-tunneling wave functions that were not too strongly mixed could be fitted within measurement uncertainty by an effective vibration-tunneling Hamiltonian. A fit of all observed vibration-tunneling states will require a full resonance-tunneling Hamiltonian.

Toward real-time temperature monitoring in fat and aqueous tissue during magnetic resonance-guided high-intensity focused ultrasound using a three-dimensional proton resonance frequency T1 method.

PubMed

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

2014-07-01

To present a three-dimensional (3D) segmented echoplanar imaging (EPI) pulse sequence implementation that provides simultaneously the proton resonance frequency shift temperature of aqueous tissue and the longitudinal relaxation time (T1 ) of fat during thermal ablation. The hybrid sequence was implemented by combining a 3D segmented flyback EPI sequence, the extended two-point Dixon fat and water separation, and the double flip angle T1 mapping techniques. High-intensity focused ultrasound (HIFU) heating experiments were performed at three different acoustic powers on excised human breast fat embedded in ex vivo porcine muscle. Furthermore, T1 calibrations with temperature in four different excised breast fat samples were performed, yielding an estimate of the average and variation of dT1 /dT across subjects. The water only images were used to mask the complex original data before computing the proton resonance frequency shift. T1 values were calculated from the fat-only images. The relative temperature coefficients were found in five fat tissue samples from different patients and ranged from 1.2% to 2.6%/°C. The results demonstrate the capability of real-time simultaneous temperature mapping in aqueous tissue and T1 mapping in fat during HIFU ablation, providing a potential tool for treatment monitoring in organs with large fat content, such as the breast. Copyright © 2013 Wiley Periodicals, Inc.

Molecular characterization and comparison of shale oils generated by different pyrolysis methods

USGS Publications Warehouse

Birdwell, Justin E.; Jin, Jang Mi; Kim, Sunghwan

2012-01-01

Shale oils generated using different laboratory pyrolysis methods have been studied using standard oil characterization methods as well as Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) with electrospray ionization (ESI) and atmospheric photoionization (APPI) to assess differences in molecular composition. The pyrolysis oils were generated from samples of the Mahogany zone oil shale of the Eocene Green River Formation collected from outcrops in the Piceance Basin, Colorado, using three pyrolysis systems under conditions relevant to surface and in situ retorting approaches. Significant variations were observed in the shale oils, particularly the degree of conjugation of the constituent molecules and the distribution of nitrogen-containing compound classes. Comparison of FT-ICR MS results to other oil characteristics, such as specific gravity; saturate, aromatic, resin, asphaltene (SARA) distribution; and carbon number distribution determined by gas chromatography, indicated correspondence between higher average double bond equivalence (DBE) values and increasing asphaltene content. The results show that, based on the shale oil DBE distributions, highly conjugated species are enriched in samples produced under low pressure, high temperature conditions, and under high pressure, moderate temperature conditions in the presence of water. We also report, for the first time in any petroleum-like substance, the presence of N4 class compounds based on FT-ICR MS data. Using double bond equivalence and carbon number distributions, structures for the N4 class and other nitrogen-containing compounds are proposed.

Effect of multiple plasmon excitation on single, double and multiple ionizations of C60 in collisions with fast highly charged Si ions

NASA Astrophysics Data System (ADS)

Kelkar, A. H.; Kadhane, U.; Misra, D.; Kumar, A.; Tribedi, L. C.

2007-06-01

We have investigated the single and multiple ionizations of the C60 molecule in collisions with fast Siq+ projectiles for various projectile charge states (q) between q = 6 and 14. The q-dependence of the ionization cross sections and their ratios is compared with the giant dipole plasmon resonance (GDPR) model. The excellent qualitative agreement with the model in case of single and double ionizations and also a reasonable agreement with the triple (and to some extent with quadruple) ionization (without evaporation) yields signify dominant contributions of the single-, double- and triple-plasmon excitations on the single- and multiple-ionization process.

Multiple ionization of C 60 in collisions with 2.33 MeV/u O-ions and giant plasmon excitation

NASA Astrophysics Data System (ADS)

Kelkar, A. H.; Kadhane, U.; Misra, D.; Kumar, Ajay; Tribedi, L. C.

2007-03-01

Single and multiple ionization of C60 in collisions with fast (v = 9.7 a.u.) Oq+ ions have been studied. Relative cross sections for production of C 601+ to C 604+ have been measured. The intensity ratios of double-to-single ionization agree very well with a model based on giant dipole plasmon resonance (GDPR). Almost linear increasing trend of the yields of single and double ionizations with projectile charge state is well reproduced by the single and double plasmon excitation mechanisms. The observed charge state independence of triple and quadruple ionization is in sharp contrast to the GDPR model.

Doubling down on naturalness with a supersymmetric twin Higgs

NASA Astrophysics Data System (ADS)

Craig, Nathaniel; Howe, Kiel

2014-03-01

We show that naturalness of the weak scale can be comfortably reconciled with both LHC null results and observed Higgs properties provided the double protection of supersymmetry and the twin Higgs mechanism. This double protection radically alters conventional signs of naturalness at the LHC while respecting gauge coupling unification and precision electroweak limits. We find the measured Higgs mass, couplings, and percent-level naturalness of the weak scale are compatible with stops at ~ 3.5 TeV and higgsinos at ~ 1 TeV. The primary signs of naturalness in this scenario include modifications of Higgs couplings, a modest invisible Higgs width, resonant Higgs pair production, and an invisibly-decaying heavy Higgs.

Stable continuous-wave single-frequency Nd:YAG blue laser at 473 nm considering the influence of the energy-transfer upconversion.

PubMed

Wang, Yaoting; Liu, Jianli; Liu, Qin; Li, Yuanji; Zhang, Kuanshou

2010-06-07

We report a continuous-wave (cw) single frequency Nd:YAG blue laser at 473 nm end-pumped by a laser diode. A ring laser resonator was designed, the frequency doubling efficiency and the length of nonlinear crystal were optimized based on the investigation of the influence of the frequency doubling efficiency on the thermal lensing effect induced by energy-transfer upconversion. By intracavity frequency doubling with PPKTP crystal, an output power of 1 W all-solid-state cw blue laser of single-frequency operation was achieved. The stability of the blue output power was better than +/- 1.8% in the given four hours.

IR-IR Conformation Specific Spectroscopy of Na +(Glucose) Adducts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Voss, Jonathan M.; Kregel, Steven J.; Fischer, Kaitlyn C.

Here in this paper we report an IR-IR double resonance study of the structural landscape present in the Na +(glucose) complex. Our experimental approach involves minimal modifications to a typical IR predissociation setup, and can be carried out via ion-dip or isomer-burning methods, providing additional flexibility to suit different experimental needs. In the current study, the single-laser IR predissociation spectrum of Na +(glucose), which clearly indicates contributions from multiple structures, was experimentally disentangled to reveal the presence of three α-conformers and five β-conformers. Comparisons with calculations show that these eight conformations correspond to the lowest energy gas-phase structures with distinctivemore » Na+ coordination.« less

Aggression and Quantitative MRI Measures of Caudate in Patients With Chronic Schizophrenia or Schizoaffective Disorder

PubMed Central

Hoptman, Matthew J.; Volavka, Jan; Czobor, Pál; Gerig, Guido; Chakos, Miranda; Blocher, Joseph; Citrome, Leslie L.; Sheitman, Brain; Lindenmayer, Jean-Pierre; Lieberman, Jeffrey A.; Bilder, Robert M.

2007-01-01

Caudate dysfunction is implicated in schizophrenia. However, little is known about the relationship between aggression and caudate volumes. Forty-nine patients received magnetic resonance imaging scanning in a double-blind treatment study in which aggression was measured. Caudate volumes were computed using a semiautomated method. The authors measured aggression with the Overt Aggression Scale and the Positive and Negative Syndrome Scale. Larger caudate volumes were associated with greater levels of aggression. The relationship between aggression and caudate volumes may be related to the iatrogenic effects of long-term treatment with typical anti-psychotic agents or to a direct effect of schizophrenic processes on the caudate. PMID:17135376

IR-IR Conformation Specific Spectroscopy of Na +(Glucose) Adducts

DOE PAGES

Voss, Jonathan M.; Kregel, Steven J.; Fischer, Kaitlyn C.; ...

2017-09-27

Here in this paper we report an IR-IR double resonance study of the structural landscape present in the Na +(glucose) complex. Our experimental approach involves minimal modifications to a typical IR predissociation setup, and can be carried out via ion-dip or isomer-burning methods, providing additional flexibility to suit different experimental needs. In the current study, the single-laser IR predissociation spectrum of Na +(glucose), which clearly indicates contributions from multiple structures, was experimentally disentangled to reveal the presence of three α-conformers and five β-conformers. Comparisons with calculations show that these eight conformations correspond to the lowest energy gas-phase structures with distinctivemore » Na+ coordination.« less

Method and apparatus for two-dimensional spectroscopy

DOEpatents

DeCamp, Matthew F.; Tokmakoff, Andrei

2010-10-12

Preferred embodiments of the invention provide for methods and systems of 2D spectroscopy using ultrafast, first light and second light beams and a CCD array detector. A cylindrically-focused second light beam interrogates a target that is optically interactive with a frequency-dispersed excitation (first light) pulse, whereupon the second light beam is frequency-dispersed at right angle orientation to its line of focus, so that the horizontal dimension encodes the spatial location of the second light pulse and the first light frequency, while the vertical dimension encodes the second light frequency. Differential spectra of the first and second light pulses result in a 2D frequency-frequency surface equivalent to double-resonance spectroscopy. Because the first light frequency is spatially encoded in the sample, an entire surface can be acquired in a single interaction of the first and second light pulses.

Combining multinuclear high-resolution solid-state MAS NMR and computational methods for resonance assignment of glutathione tripeptide.

PubMed

Sardo, Mariana; Siegel, Renée; Santos, Sérgio M; Rocha, João; Gomes, José R B; Mafra, Luis

2012-06-28

We present a complete set of experimental approaches for the NMR assignment of powdered tripeptide glutathione at natural isotopic abundance, based on J-coupling and dipolar NMR techniques combined with (1)H CRAMPS decoupling. To fully assign the spectra, two-dimensional (2D) high-resolution methods, such as (1)H-(13)C INEPT-HSQC/PRESTO heteronuclear correlations (HETCOR), (1)H-(1)H double-quantum (DQ), and (1)H-(14)N D-HMQC correlation experiments, have been used. To support the interpretation of the experimental data, periodic density functional theory calculations together with the GIPAW approach have been used to calculate the (1)H and (13)C chemical shifts. It is found that the shifts calculated with two popular plane wave codes (CASTEP and Quantum ESPRESSO) are in excellent agreement with the experimental results.

Excited state baryon spectroscopy from lattice QCD

DOE PAGES

Robert G. Edwards; Dudek, Jozef J.; Richards, David G.; ...

2011-10-31

Here, we present a calculation of the Nucleon and Delta excited state spectrum on dynamical anisotropic clover lattices. A method for operator construction is introduced that allows for the reliable identification of the continuum spins of baryon states, overcoming the reduced symmetry of the cubic lattice. Using this method, we are able to determine a spectrum of single-particle states for spins up to and including $J = 7/2$, of both parities, the first time this has been achieved in a lattice calculation. We find a spectrum of states identifiable as admixtures of $SU(6) Ⓧ O(3)$ representations and a counting ofmore » levels that is consistent with the non-relativistic $qqq$ constituent quark model. This dense spectrum is incompatible with quark-diquark model solutions to the "missing resonance problem" and shows no signs of parity doubling of states.« less

Measurements of the {sup 116}Cd(p,n) and {sup 116}Sn(n,p) reactions at 300 MeV for studying Gamow-Teller transition strengths in the intermediate nucleus of the {sup 116}Cd double-{beta} decay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sasano, M.; Kuboki, H.; Sekiguchi, K.

2009-11-09

The double differential cross sections for the {sup 116}Cd(p,n) and {sup 116}Sn(n,p) reactions at 300 MeV have been measured over a wide excitation-energy region including Gamow-Teller (GT) giant resonance (GTGR) for studying GT transition strengths in the intermediate nucleus of the {sup 116}Cd double-{beta} decay, namely {sup 116}In. A large amount of the strengths in the {beta}{sup +} direction has been newly found in the energy region up to 30 MeV, which may imply that the GT strengths in the GTGR region contribute to the nuclear matrix element of the two-neutrino double-{beta} decay.

Drive-level dependence of doubly rotated langasite resonators with different configurations.

PubMed

Zhang, Haifeng; Kosinski, John; Xie, Yuan; Turner, Joseph

2013-05-01

The miniaturization of crystal resonators and filters toward the micro electromechanical systems (MEMS) and nano-structured scales demands improvement of nonlinear piezoelectricity theory and a better understanding of the nonlinear behavior of new crystal materials. The nonlinearities affect the quality factor and acoustic behavior of MEMS and nano-structured resonators and filters. Among these nonlinear effects, drive-level dependence (DLD), which describes the instability of the resonator frequency resulting from voltage level and/or power density, is a potentially significant problem for miniaturized resonators. Langasite, a promising new piezoelectric material, is of current interest for a variety of applications because of its good temperature behavior, good piezoelectric coupling, low acoustic loss, and high Q-factor. It has been recently used to make high-temperature MEMS. In this paper, we report experimental measurements of the DLD of langasite resonators with different resonator configurations (plano-plano, single bevel, and double bevel). The results show that the resonator configuration affects the DLD of the langasite resonator. The DLD measurement results for langasite are compared with literature values for quartz, langaniste, and langatate, and with additional new measurements for a GaPO4 resonator of type R-30 (-11.1° rotated Y-cut). Uncertainty analysis for the measured drive-level sensitivity is performed as well.

Ferromagnetic resonance in coupled permalloy double films separated by a Cu interlayer

NASA Astrophysics Data System (ADS)

Maksymowicz, A. Z.; Whiting, J. S. S.; Watson, M. L.; Chambers, A.

1991-03-01

Ferromagnetic resonance (FMR) at 16 GHz was used to study the magnetic coupling between two-layers of permalloy separated by a nonmagnetic Cu layer. Samples with the same thickness (600 Å) of both permalloy layers were deposited from e-gun sources onto glass substrates in UHV. The thickness d of the Cu interlayer was varied from 5 to 37 Å. The exchange coupling energy ( E = - KM1· M2) model was used to describe the interaction between the two magnetic layers. It was found from the ferromagnetic resonance data in the perpendicular configuration that K( d) follows an exponential law, K = K0e - d/ q, where q = 9.3 Å.

First resonant tunneling via a light-hole ground state

NASA Astrophysics Data System (ADS)

Lampin, J. F.; Mollot, F.

1998-07-01

We report the demonstration of resonant tunneling of light-holes through an AlAs/GaAs 0.7P 0.3 double-barrier heterostructure. The tensile strain in the quantum well reverses the order of the light- and heavy-hole levels, the first light-hole level becoming the ground state. The I( V) characteristics are measured at different temperatures and compared to those of a standard AlAs/GaAs unstrained structure. The peak current density of the first light-hole resonance and its peak-to-valley current ratio are enhanced. They reach 28 A/cm 2 and 3.4 : 1 at 15 K. A negative differential resistance is observed up to 250 K.

Power and stability limitations of resonant tunneling diodes

NASA Technical Reports Server (NTRS)

Kidner, C.; Mehdi, I.; East, J. R.; Haddad, G. I.

1990-01-01

Stability criteria for resonant tunneling diodes are investigated. Details of how extrinsic elements, such as series inductance and parallel capacitance, affect the stability are presented. A GaAs/AlAs/InGaAs/AlAs/GaAs double-barrier diode is investigated, showing the effect of different modes of low-frequency oscillation and the extrinsic circuit required for stabilization. The effect of device stabilization on high-frequency power generation is described. The main conclusions of the paper are: (1) stable resonant tunneling diode operation is difficult to obtain, and (2) the circuit and device conditions required for stable operation greatly reduce the amount of power that can be produced by these devices.

Role of phase breaking processes on resonant spin transfer torque nano-oscillators

NASA Astrophysics Data System (ADS)

Sharma, Abhishek; Tulapurkar, Ashwin A.; Muralidharan, Bhaskaran

2018-05-01

Spin transfer torque nano-oscillators (STNOs) based on magnetoresistance and spin transfer torque effects find potential applications in miniaturized wireless communication devices. Using the non-coherent non-equilibrium Green's function spin transport formalism self-consistently coupled with the stochastic Landau-Lifshitz-Gilbert-Slonczewski's equation and the Poisson's equation, we elucidate the role of elastic phase breaking on the proposed STNO design featuring double barrier resonant tunneling. Demonstrating the immunity of our proposed design, we predict that despite the presence of elastic dephasing, the resonant tunneling magnetic tunnel junction structures facilitate oscillator designs featuring a large enhancement in microwave power up to 8μW delivered to a 50Ω load.

Diode laser based resonance ionization mass spectrometric measurement of strontium-90

NASA Astrophysics Data System (ADS)

Bushaw, B. A.; Cannon, B. D.

1997-10-01

A diode laser based scheme for the isotopically selective excitation and ionization of strontium is presented. The double-resonance excitation 5s 21S 0→5s5p 3P 1→5s6s 3S 1 is followed by photoionization at 488 nm. The isotope shifts and hyperfine structure in the resonance transitions have been accurately measured for the stable isotopes and 90Sr, with the measurement of the 90Sr shifts using sub-pg samples. Analytical tests, using graphite crucible atomization, demonstrated 90Sr detection limits of 0.8 fg and overall (optical+mass spectrometer) isotopic selectivity of >10 10 against stable strontium.

Vibration modes interference in the MEMS resonant pressure sensor

NASA Astrophysics Data System (ADS)

Zhang, Fangfang; Li, Anlin; Bu, Zhenxiang; Wang, Lingyun; Sun, Daoheng; Du, Xiaohui; Gu, Dandan

2017-11-01

A new type of coupled balanced-mass double-ended tuning fork resonator (CBDETF) pressure sensor is fabricated and tested. However, the low accuracy of the CBDETF pressure sensor is not satisfied to us. Based on systematic analysis and tests, the coupling effect between the operational mode and interference mode is considered to be the main cause for the sensor in accuracy. To solve this problem, the stiffness of the serpentine beams is increased to pull up the resonant frequency of the interfering mode and make it separate far from the operational mode. Finally, the accuracy of the CBDETF pressure sensor is improved from + /-0.5% to less than + /-0.03% of the Full Scale (F.S.).

Sequentially evaporated thin film YBa2Cu3O(7-x) superconducting microwave ring resonator

NASA Technical Reports Server (NTRS)

Rohrer, Norman J.; To, Hing Y.; Valco, George J.; Bhasin, Kul B.; Chorey, Chris; Warner, Joseph D.

1990-01-01

There is great interest in the application of thin film high temperature superconductors in high frequency electronic circuits. A ring resonator provides a good test vehicle for assessing the microwave losses in the superconductor and for comparing films made by different techniques. Ring resonators made of YBa2Cu3O(7-x) have been investigated on LaAlO3 substrates. The superconducting thin films were deposited by sequential electron beam evaporation of Cu, Y, and BaF2 with a post anneal. Patterning of the superconducting film was done using negative photolithography. A ring resonator was also fabricated from a thin gold film as a control. Both resonators had a gold ground plane on the backside of the substrate. The ring resonators' reflection coefficients were measured as a function of frequency from 33 to 37 GHz at temperatures ranging from 20 K to 68 K. The resonator exhibited two resonances which were at 34.5 and 35.7 GHz at 68 K. The resonant frequencies increased with decreasing temperature. The magnitude of the reflection coefficients was in the calculation of the unloaded Q-values. The performance of the evaporated and gold resonator are compared with the performance of a laser ablated YBa2Cu3O(7-x) resonator. The causes of the double resonance are discussed.

Physical properties of YBa 2Cu 3O 7- δ thin films using microstrip ring resonators technique

NASA Astrophysics Data System (ADS)

Lai, L. S.; Zeng, H. K.; Juang, J. Y.; Wu, K. H.; Uen, T. M.; Lin, J. Y.; Gou, Y. S.

2006-09-01

Microstrip ring resonators with quality factor ( Q) over 10 4 at temperature 5 K, were fabricated using the double-side YBa 2Cu 3O 7- δ (YBCO) epitaxial films deposited on LaAlO 3 (LAO) substrates. By placing a narrow gap in the ring resonator, we observed that the original fundamental resonating mode (resonance frequency f = 3.61 GHz) splits into a dual-mode with different resonating frequencies ( f = 1.80 GHz and f = 5.33 GHz). These two kinds of the resonator allow us to determine the temperature and frequency dependences of the magnetic penetration depth λ( T, f) and the surface loss. Several salient features of the above findings related to the nature of low-lying excitations for high- Tc superconductivity as a function of oxygen content will be elucidated. In particular, the current models, suggested by Wen and Lee, will be examined in a quantitative manner. It allows us to give a justification of quasiparticle as Fermi-liquid in the superconducting state. In addition, an equivalent inductance circuit model is suggested to account for the occurrence of the dual-mode resonance.

Nonmonotonous electron mobility due to structurally induced resonant coupling of subband states in an asymmetric double quantum well

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nayak, R. K.; Das, S.; Panda, A. K.

We show that sharp nonmonotic variation of low temperature electron mobility μ can be achieved in GaAs/Al{sub x}Ga{sub 1-x}As barrier delta-doped double quantum well structure due to quantum mechanical transfer of subband electron wave functions within the wells. We vary the potential profile of the coupled structure as a function of the doping concentration in order to bring the subbands into resonance such that the subband energy levels anticross and the eigen states of the coupled structure equally share both the wells thereby giving rise to a dip in mobility. When the wells are of equal widths, the dip inmore » mobility occurs under symmetric doping of the side barriers. In case of unequal well widths, the resonance can be obtained by suitable asymmetric variation of the doping concentrations. The dip in mobility becomes sharp and also the wavy nature of mobility takes a rectangular shape by increasing the barrier width. We show that the dip in mobility at resonance is governed by the interface roughness scattering through step like changes in the subband mobilities. It is also gratifying to show that the drop in mobility at the onset of occupation of second subband is substantially supressed through the quantum mechanical transfer of subband wave functions between the wells. Our results can be utilized for performance enhancement of coupled quantum well devices.« less

Electron spin resonance and proton matrix electron nuclear double resonance studies of N,N,N[prime],N[prime]-tetramethylbenzidine photoionization in sodium and lithium dodecyl sulfate micelles: Structural effects of crown ethers

DOE Office of Scientific and Technical Information (OSTI.GOV)

McManus, H.J.D.; Young Soo Kang; Kevan, L.

1993-01-07

The study of model membrane systems enjoys increasing attention within the area of solar energy research. An electron nuclear double resonance and electron spin resonance study of photogenerated N,N,N[prime],N[prime]-tetramethylbenzidine (TMB) cation in frozen suspensions of lithium (LDS) and sodium (SDS) dodecyl sulfate micelles containing various concentrations of cyclic polyethers was undertaken. The relative location of the TMB cation within the organic aggregate was determined from the proton matrix ENDOR line width at 142 K. A broader line width was observed in LDS compared to SDS micelles, which is due to the fact that the larger lithium cation opens the micellarmore » interface resulting in increased hydration and deeper solubilization of TMB. The proton matrix ENDOR line width decreased upon addition of crown ethers. This decrease may be explained by displacement of the TMB toward the interface as a result of the decrease in ionic strength caused by the complexation of the countercations. The photoyield shows a slight increase with addition of crown ethers. This increase is most likely caused by the increase in the effective anionic charge of the micelle effected by the complexation of the sodium or lithium ions by the crown ethers. This increase in the anionic charge mitigates the rate of thermal back electron transfer resulting in an increased photoyield. 54 refs., 6 figs., 2 tabs.« less

In Vivo Proton–Electron Double-Resonance Imaging of Extracellular Tumor pH Using an Advanced Nitroxide Probe

PubMed Central

Samouilov, Alexandre; Efimova, Olga V.; Bobko, Andrey A.; Sun, Ziqi; Petryakov, Sergey; Eubank, Timothy D.; Trofimov, Dmitrii G.; Kirilyuk, Igor A.; Grigor’ev, Igor A.; Takahashi, Wataru; Zweier, Jay L.; Khramtsov, Valery V.

2014-01-01

A variable radio frequency proton–electron double-resonance imaging (VRF PEDRI) approach for pH mapping of aqueous samples has been recently developed (Efimova et al. J. Magn. Reson. 2011, 209, 227–232). A pH map is extracted from two PEDRI acquisitions performed at electron paramagnetic resonance (EPR) frequencies of protonated and unprotonated forms of a pH-sensitive probe. To translate VRF PEDRI to an in vivo setting, an advanced pH probe was synthesized. Probe deuteration resulted in a narrow spectral line of 1.2 G compared to a nondeuterated analogue line width of 2.1 G allowing for an increase of Overhauser enhancements and reduction in rf power deposition. Binding of the probe to the cell-impermeable tripeptide, glutathione (GSH), allows for targeting to extracellular tissue space for monitoring extracellular tumor acidosis, a prognostic factor in tumor pathophysiology. The probe demonstrated pH sensitivity in the 5.8–7.8 range, optimum for measurement of acidic extracellular tumor pH (pHe). In vivo VRF PEDRI was performed on Met-1 tumor-bearing mice. Compared to normal mammary glands with a neutral mean pHe (7.1 ± 0.1), we observed broader pH distribution with acidic mean pHe (6.8 ± 0.1) in tumor tissue. In summary, VRF PEDRI in combination with a newly developed pH probe provides an analytical approach for spatially resolved noninvasive pHe monitoring, in vivo. PMID:24372284

Proton nuclear magnetic resonance studies on the variant-3 neurotoxin from Centruroides sculpturatus Ewing: Sequential assignment of resonances

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nettesheim, D.G.; Klevit, R.E.; Drobny, G.

1989-02-21

The authors report the sequential assignment of resonances to specific residues in the proton nuclear magnetic resonance spectrum of the variant-3 neurotoxin from the scorpion Centruroides sculpturatus Ewing (range southwestern U.S.A.). A combination of two-dimensional NMR experiments such as 2D-COSY, 2D-NOESY, and single- and double-RELAY coherence transfer spectroscopy has been employed on samples of the protein dissolved in D{sub 2}O and in H{sub 2}O for assignment purposes. These studies provide a basis for the determination of the solution-phase conformation of this protein and for undertaking detailed structure-function studies of these neurotoxins that modulate the flow of sodium current by bindingmore » to the sodium channels of excitable membranes.« less

Contribution of the magnetic resonance to the third harmonic generation from a fishnet metamaterial

NASA Astrophysics Data System (ADS)

Reinhold, J.; Shcherbakov, M. R.; Chipouline, A.; Panov, V. I.; Helgert, C.; Paul, T.; Rockstuhl, C.; Lederer, F.; Kley, E.-B.; Tünnermann, A.; Fedyanin, A. A.; Pertsch, T.

2012-09-01

We investigate experimentally and theoretically the third harmonic generated by a double-layer fishnet metamaterial. To unambiguously disclose most notably the influence of the magnetic resonance, the generated third harmonic was measured as a function of the angle of incidence. It is shown experimentally and numerically that when the magnetic resonance is excited by a pump beam, the angular dependence of the third harmonic signal has a local maximum at an incidence angle of θ≃20∘. This maximum is shown to be a fingerprint of the antisymmetric distribution of currents in the gold layers. An analytical model based on the nonlinear dynamics of the electrons inside the gold shows excellent agreement with experimental and numerical results. This clearly indicates the difference in the third harmonic angular pattern at electric and magnetic resonances of the metamaterial.

Push-pull radio frequency circuit with integral transistion to waveguide output

DOEpatents

Bennett, Wilfred P.

1987-01-01

A radio frequency circuit for ICRF heating includes a resonant push-pull circuit, a double ridged rectangular waveguide, and a coupling transition which joins the waveguide to the resonant circuit. The resonant circuit includes two cylindrical conductors mounted side by side and two power vacuum tubes attached to respective ends of a cylindrical conductor. A conductive yoke is located at the other end of the cylindrical conductors to short circuit the two cylindrical conductors. The coupling transition includes two relatively flat rectangular conductors extending perpendicular to the longitudinal axes of a respective cylindrical conductor to which the flat conductor is attached intermediate the ends thereof. Conductive side covers and end covers are also provided for forming pockets in the waveguide into which the flat conductors extend when the waveguide is attached to a shielding enclosure surrounding the resonant circuit.

Using the charge-stabilization technique in the double ionization potential equation-of-motion calculations with dianion references.

PubMed

Kuś, Tomasz; Krylov, Anna I

2011-08-28

The charge-stabilization method is applied to double ionization potential equation-of-motion (EOM-DIP) calculations to stabilize unstable dianion reference functions. The auto-ionizing character of the dianionic reference states spoils the numeric performance of EOM-DIP limiting applications of this method. We demonstrate that reliable excitation energies can be computed by EOM-DIP using a stabilized resonance wave function instead of the lowest energy solution corresponding to the neutral + free electron(s) state of the system. The details of charge-stabilization procedure are discussed and illustrated by examples. The choice of optimal stabilizing Coulomb potential, which is strong enough to stabilize the dianion reference, yet, minimally perturbs the target states of the neutral, is the crux of the approach. Two algorithms of choosing optimal parameters of the stabilization potential are presented. One is based on the orbital energies, and another--on the basis set dependence of the total Hartree-Fock energy of the reference. Our benchmark calculations of the singlet-triplet energy gaps in several diradicals show a remarkable improvement of the EOM-DIP accuracy in problematic cases. Overall, the excitation energies in diradicals computed using the stabilized EOM-DIP are within 0.2 eV from the reference EOM spin-flip values. © 2011 American Institute of Physics

Optimization of transversal relaxation of nitroxides for pulsed electron-electron double resonance spectroscopy in phospholipid membranes.

PubMed

Dastvan, Reza; Bode, Bela E; Karuppiah, Muruga Poopathi Raja; Marko, Andriy; Lyubenova, Sevdalina; Schwalbe, Harald; Prisner, Thomas F

2010-10-28

Pulsed electron-electron double resonance (PELDOR) spectroscopy is increasingly applied to spin-labeled membrane proteins. However, after reconstitution into liposomes, spin labels often exhibit a much faster transversal relaxation (T(m)) than in detergent micelles, thus limiting application of the method in lipid bilayers. In this study, the main reasons for enhanced transversal relaxation in phospholipid membranes were investigated systematically by use of spin-labeled derivatives of stearic acid and phosphatidylcholine as well as spin-labeled derivatives of the channel-forming peptide gramicidin A under the conditions typically employed for PELDOR distance measurements. Our results clearly show that dephasing due to instantaneous diffusion that depends on dipolar interaction among electron spins is an important contributor to the fast echo decay in cases of high local concentrations of spin labels in membranes. The main difference between spin labels in detergent micelles and membranes is their local concentration. Consequently, avoiding spin clustering and suppressing instantaneous diffusion is the key step for maximizing PELDOR sensitivity in lipid membranes. Even though proton spin diffusion is an important relaxation mechanism, only in samples of low local concentrations does deuteration of acyl chains and buffer significantly prolong T(m). In these cases, values of up to 7 μs have been achieved. Furthermore, our study revealed that membrane composition and labeling position in the membrane can also affect T(m), either by promoting the segregation of spin-labeled species or by altering their exposure to matrix protons. Effects of other experimental parameters including temperature (<50 K), presence of oxygen, and cryoprotectant type are negligible under our experimental conditions.

Pharmacologic Modulation of Hand Pain in Osteoarthritis: A Double-Blind Placebo-Controlled Functional Magnetic Resonance Imaging Study Using Naproxen

PubMed Central

Sanders, Duncan; Krause, Kristina; O'Muircheartaigh, Jonathan; Thacker, Michael A; Huggins, John P; Vennart, William; Massat, Nathalie J; Choy, Ernest; Williams, Steven C R; Howard, Matthew A

2015-01-01

Objective In an attempt to shed light on management of chronic pain conditions, there has long been a desire to complement behavioral measures of pain perception with measures of underlying brain mechanisms. Using functional magnetic resonance imaging (fMRI), we undertook this study to investigate changes in brain activity following the administration of naproxen or placebo in patients with pain related to osteoarthritis (OA) of the carpometacarpal (CMC) joint. Methods A placebo-controlled, double-blind, 2-period crossover study was performed in 19 individuals with painful OA of the CMC joint of the right hand. Following placebo or naproxen treatment periods, a functionally relevant task was performed, and behavioral measures of the pain experience were collected in identical fMRI examinations. Voxelwise and a priori region of interest analyses were performed to detect between-period differences in brain activity. Results Significant reductions in brain activity following treatment with naproxen, compared to placebo, were observed in brain regions commonly associated with pain perception, including the bilateral primary somatosensory cortex, thalamus, and amygdala. Significant relationships between changes in perceived pain intensity and changes in brain activity were also observed in brain regions previously associated with pain intensity. Conclusion This study demonstrates the sensitivity of fMRI to detect the mechanisms underlying treatments of known efficacy. The data illustrate the enticing potential of fMRI as an adjunct to self-report for detecting early signals of efficacy of novel therapies, both pharmacologic and nonpharmacologic, in small numbers of individuals with persistent pain. PMID:25533872

Temperature determination of resonantly excited plasmonic branched gold nanoparticles by X-ray absorption spectroscopy.

PubMed

Van de Broek, Bieke; Grandjean, Didier; Trekker, Jesse; Ye, Jian; Verstreken, Kris; Maes, Guido; Borghs, Gustaaf; Nikitenko, Sergey; Lagae, Liesbet; Bartic, Carmen; Temst, Kristiaan; Van Bael, Margriet J

2011-09-05

The fields of bioscience and nanomedicine demand precise thermometry for nanoparticle heat characterization down to the nanoscale regime. Since current methods often use indirect and less accurate techniques to determine the nanoparticle temperature, there is a pressing need for a direct and reliable element-specific method. In-situ extended X-ray absorption fine structure (EXAFS) spectroscopy is used to determine the thermo-optical properties of plasmonic branched gold nanoparticles upon resonant laser illumination. With EXAFS, the direct determination of the nanoparticle temperature increase upon laser illumination is possible via the thermal influence on the gold lattice parameters. More specifically, using the change of the Debye-Waller term representing the lattice disorder, the temperature increase is selectively measured within the plasmonic branched nanoparticles upon resonant laser illumination. In addition, the signal intensity shows that the nanoparticle concentration in the beam more than doubles during laser illumination, thereby demonstrating that photothermal heating is a dynamic process. A comparable temperature increase is measured in the nanoparticle suspension using a thermocouple. This good correspondence between the temperature at the level of the nanoparticle and at the level of the suspension points to an efficient heat transfer between the nanoparticle and the surrounding medium, thus confirming the potential of branched gold nanoparticles for hyperthermia applications. This work demonstrates that X-ray absorption spectroscopy-based nanothermometry could be a valuable tool in the fast-growing number of applications of plasmonic nanoparticles, particularly in life sciences and medicine. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lithographically patterned electrodeposition of gold, silver, and nickel nanoring arrays with widely tunable near-infrared plasmonic resonances.

PubMed

Halpern, Aaron R; Corn, Robert M

2013-02-26

A novel low-cost nanoring array fabrication method that combines the process of lithographically patterned nanoscale electrodeposition (LPNE) with colloidal lithography is described. Nanoring array fabrication was accomplished in three steps: (i) a thin (70 nm) sacrificial nickel or silver film was first vapor-deposited onto a plasma-etched packed colloidal monolayer; (ii) the polymer colloids were removed from the surface, a thin film of positive photoresist was applied, and a backside exposure of the photoresist was used to create a nanohole electrode array; (iii) this array of nanoscale cylindrical electrodes was then used for the electrodeposition of gold, silver, or nickel nanorings. Removal of the photoresist and sacrificial metal film yielded a nanoring array in which all of the nanoring dimensions were set independently: the inter-ring spacing was fixed by the colloidal radius, the radius of the nanorings was controlled by the plasma etching process, and the width of the nanorings was controlled by the electrodeposition process. A combination of scanning electron microscopy (SEM) measurements and Fourier transform near-infrared (FT-NIR) absorption spectroscopy were used to characterize the nanoring arrays. Nanoring arrays with radii from 200 to 400 nm exhibited a single strong NIR plasmonic resonance with an absorption maximum wavelength that varied linearly from 1.25 to 3.33 μm as predicted by a simple standing wave model linear antenna theory. This simple yet versatile nanoring array fabrication method was also used to electrodeposit concentric double gold nanoring arrays that exhibited multiple NIR plasmonic resonances.

Precision atomic beam density characterization by diode laser absorption spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oxley, Paul; Wihbey, Joseph

2016-09-15

We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident lasermore » light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10{sup −5} are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10{sup 4} atoms cm{sup −3}. The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.« less

Precision atomic beam density characterization by diode laser absorption spectroscopy.

PubMed

Oxley, Paul; Wihbey, Joseph

2016-09-01

We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10 -5 are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10 4 atoms cm -3 . The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

Search for Spin Filtering By Electron Tunneling Through Ferromagnetic EuS Barriers in Pbs

NASA Technical Reports Server (NTRS)

Figielski, T.; Morawski, A.; Wosinski, T.; Wrotek, S.; Makosa, A.; Lusakowska, E.; Story, T.; Sipatov, A. Yu.; Szczerbakow, A.; Grasza, K.;

Giant plasmon excitation in single and double ionization of C60 by fast highly charged Si and O ions

NASA Astrophysics Data System (ADS)

Kelkar, A. H.; Kadhane, U.; Misra, D.; Tribedi, L. C.

2007-09-01

Se have investigated single and double ionization of C60 molecule in collisions with 2.33 MeV/u Siq+ (q=6-14) and 3.125 MeV/u Oq+ (q=5-8) projectiles. The projectile charge state dependence of the single and double ionization yields of C60 are then compared to those for an ion-atom collision system using Ne gas as a target. A large difference between the gas and the cluster target behaviour was partially explained in terms of a model based on collective excitation namely the giant dipole plasmon resonance (GDPR). The qualitative agreement between the data and GDPR model prediction for single and double ionization signifies the importance of single and double plasmon excitations in the ionization process. A large deviation of the GDPR model for triple and quadruple ionization from the experimental data imply the importance of the other low impact parameter processes such as evaporation, fragmentation and a possible solid-like dynamical screening.

Lesion-induced DNA weak structural changes detected by pulsed EPR spectroscopy combined with site-directed spin labelling.

PubMed

Sicoli, Giuseppe; Mathis, Gérald; Aci-Sèche, Samia; Saint-Pierre, Christine; Boulard, Yves; Gasparutto, Didier; Gambarelli, Serge

2009-06-01

Double electron-electron resonance (DEER) was applied to determine nanometre spin-spin distances on DNA duplexes that contain selected structural alterations. The present approach to evaluate the structural features of DNA damages is thus related to the interspin distance changes, as well as to the flexibility of the overall structure deduced from the distance distribution. A set of site-directed nitroxide-labelled double-stranded DNA fragments containing defined lesions, namely an 8-oxoguanine, an abasic site or abasic site analogues, a nick, a gap and a bulge structure were prepared and then analysed by the DEER spectroscopic technique. New insights into the application of 4-pulse DEER sequence are also provided, in particular with respect to the spin probes' positions and the rigidity of selected systems. The lesion-induced conformational changes observed, which were supported by molecular dynamics studies, confirm the results obtained by other, more conventional, spectroscopic techniques. Thus, the experimental approaches described herein provide an efficient method for probing lesion-induced structural changes of nucleic acids.

Geometry effects on cooling in a standing wave cylindrical thermoacousic resonator

NASA Astrophysics Data System (ADS)

Mohd-Ghazali, Normah; Ghazali, Ahmad Dairobi; Ali, Irwan Shah; Rahman, Muhammad Aminullah A.

2012-06-01

Numerous reports have established the refrigeration applications of thermoacoustic cooling without compressors and refrigerants. Significant cooling effects can be obtained in a thermoacoustic resonator fitted with a heat exchanging stack and operated at resonance frequency. Past studies, however, have hardly referred to the fundamental relationship between resonant frequency and the resonator geometry. This paper reports the thermoacoustic cooling effects at resonance obtained by changing the diameter of the resonator while holding the length constant and vice versa. Experiments were completed at atmospheric pressure with air as the working fluid using a number of pvc tubes having parallel plate stack from Mylar. The temperature difference measured across the stack showed that a volume increase in the working fluid in general increases the temperature gradient for the quarter-and half-wavelength resonators. Doubling the diameter from 30 mm to 60 mm produced the highest temperature difference due to the greater number of stack plates resulting in a higher overall thermoacaoustic cooling. Increasing the resonator length only produced a small increase in temperature gradient since the resonant frequency at operation is only slightly changed. Investigation on the aspect ratio exhibits no influence on the temperature difference across the stack. This study have shown that the resonator length and diameter do affect the temperature difference across the thermoacoustic stack, and further research should be done to consider the contribution of the stack mass on the overall desired thermoacoustic cooling.

Modeling the growth processes of polyelectrolyte multilayers using a quartz crystal resonator.

PubMed

Salomäki, Mikko; Kankare, Jouko

2007-07-26

The layer-by-layer buildup of chitosan/hyaluronan (CH/HA) and poly(l-lysine)/hyaluronan (PLL/HA) multilayers was followed on a quartz crystal resonator (QCR) in different ionic strengths and at different temperatures. These polyelectrolytes were chosen to demonstrate the method whereby useful information is retrieved from acoustically thick polymer layers during their buildup. Surface acoustic impedance recorded in these measurements gives a single or double spiral when plotted in the complex plane. The shape of this spiral depends on the viscoelasticity of the layer material and regularity of the growth process. The polymer layer is assumed to consist of one or two zones. A mathematical model was devised to represent the separation of the layer to two zones with different viscoelastic properties. Viscoelastic quantities of the layer material and the mode and parameters of the growth process were acquired by fitting a spiral to the experimental data. In all the cases the growth process was mainly exponential as a function of deposition cycles, the growth exponent being between 0.250 and 0.275.

Comparing Laser Desorption Ionization and Atmospheric Pressure Photoionization Coupled to Fourier Transform Ion Cyclotron Resonance Mass Spectrometry To Characterize Shale Oils at the Molecular Level

USGS Publications Warehouse

Cho, Yunjo; Jin, Jang Mi; Witt, Matthias; Birdwell, Justin E.; Na, Jeong-Geol; Roh, Nam-Sun; Kim, Sunghwan

2013-01-01

Laser desorption ionization (LDI) coupled to Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to analyze shale oils. Previous work showed that LDI is a sensitive ionization technique for assessing aromatic nitrogen compounds, and oils generated from Green River Formation oil shales are well-documented as being rich in nitrogen. The data presented here demonstrate that LDI is effective in ionizing high-double-bond-equivalent (DBE) compounds and, therefore, is a suitable method for characterizing compounds with condensed structures. Additionally, LDI generates radical cations and protonated ions concurrently, the distribution of which depends upon the molecular structures and elemental compositions, and the basicity of compounds is closely related to the generation of protonated ions. This study demonstrates that LDI FT-ICR MS is an effective ionization technique for use in the study of shale oils at the molecular level. To the best of our knowledge, this is the first time that LDI FT-ICR MS has been applied to shale oils.

A Differential Resonant Accelerometer with Low Cross-Interference and Temperature Drift

PubMed Central

Li, Bo; Zhao, Yulong; Li, Cun; Cheng, Rongjun; Sun, Dengqiang; Wang, Songli

2017-01-01

Presented in this paper is a high-performance resonant accelerometer with low cross-interference, low temperature drift and digital output. The sensor consists of two quartz double-ended tuning forks (DETFs) and a silicon substrate. A new differential silicon substrate is proposed to reduce the temperature drift and cross-interference from the undesirable direction significantly. The natural frequency of the quartz DETF is theoretically calculated, and then the axial stress on the vibration beams is verified through finite element method (FEM) under a 100 g acceleration which is loaded on x-axis, y-axis and z-axis, respectively. Moreover, sensor chip is wire-bonded to a printed circuit board (PCB) which contains two identical oscillating circuits. In addition, a steel shell is selected to package the sensor for experiments. Benefiting from the distinctive configuration of the differential structure, the accelerometer characteristics such as temperature drift and cross-interface are improved. The experimental results demonstrate that the cross-interference is lower than 0.03% and the temperature drift is about 18.16 ppm/°C. PMID:28106798

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harilal, Sivanandan S.; LaHaye, Nicole L.; Phillips, Mark C.

We use a two-dimensional laser-induced fluorescence spectroscopy technique to measure the coupled absorption and emission properties of atomic species in plasmas produced via laser ablation of solid aluminum targets at atmospheric pressure. Emission spectra from the Al I 394.4 nm and Al I 396.15 nm transitions are measured while a frequency-doubled, continuous-wave, Ti:Sapphire laser is tuned across the Al I 396.15 nm transition. The resulting two-dimensional spectra show the energy coupling between the two transitions via increased emission intensity for both transitions during resonant absorption of the continuous-wave laser at one transition. Time-delayed and gated detection of the emission spectrummore » is used to isolate the resonantly-excited fluorescence emission from the thermally-excited emission from the plasma. In addition, the tunable continuous-wave laser measures the absorption spectrum of the Al transition with ultra-high resolution after the plasma has cooled, resulting in narrower spectral linewidths than observed in emission spectra. Our results highlight that fluorescence spectroscopy employing continuous-wave laser re-excitation after pulsed laser ablation combines benefits of both traditional emission and absorption spectroscopic methods.« less

The basic helix-loop-helix region of the transcriptional repressor hairy and enhancer of split 1 is preorganized to bind DNA.

PubMed

Popovic, Matija; Wienk, Hans; Coglievina, Maristella; Boelens, Rolf; Pongor, Sándor; Pintar, Alessandro

2014-04-01

Hairy and enhancer of split 1, one of the main downstream effectors in Notch signaling, is a transcriptional repressor of the basic helix-loop-helix (bHLH) family. Using nuclear magnetic resonance methods, we have determined the structure and dynamics of a recombinant protein, H1H, which includes an N-terminal segment, b1, containing functionally important phosphorylation sites, the basic region b2, required for binding to DNA, and the HLH domain. We show that a proline residue in the sequence divides the protein in two parts, a flexible and disordered N-terminal region including b1 and a structured, mainly helical region comprising b2 and the HLH domain. Binding of H1H to a double strand DNA oligonucleotide was monitored through the chemical shift perturbation of backbone amide resonances, and showed that the interaction surface involves not only the b2 segment but also several residues in the b1 and HLH regions. Copyright © 2014 Wiley Periodicals, Inc.

Definition of the intermediates and mechanism of the anticancer drug bleomycin using nuclear resonance vibrational spectroscopy and related methods

PubMed Central

Liu, Lei V.; Bell, Caleb B.; Wong, Shaun D.; Wilson, Samuel A.; Kwak, Yeonju; Chow, Marina S.; Zhao, Jiyong; Hodgson, Keith O.; Hedman, Britt; Solomon, Edward I.

2010-01-01

Bleomycin (BLM) is a glycopeptide anticancer drug capable of effecting single- and double-strand DNA cleavage. The last detectable intermediate prior to DNA cleavage is a low spin FeIII peroxy level species, termed activated bleomycin (ABLM). DNA strand scission is initiated through the abstraction of the C-4′ hydrogen atom of the deoxyribose sugar unit. Nuclear resonance vibrational spectroscopy (NRVS) aided by extended X-ray absorption fine structure spectroscopy and density functional theory (DFT) calculations are applied to define the natures of FeIIIBLM and ABLM as (BLM)FeIII─OH and (BLM)FeIII(η1─OOH) species, respectively. The NRVS spectra of FeIIIBLM and ABLM are strikingly different because in ABLM the δFe─O─O bending mode mixes with, and energetically splits, the doubly degenerate, intense O─Fe─Nax transaxial bends. DFT calculations of the reaction of ABLM with DNA, based on the species defined by the NRVS data, show that the direct H-atom abstraction by ABLM is thermodynamically favored over other proposed reaction pathways. PMID:21149675

System Architectures Near the 2:1 Resonance

NASA Astrophysics Data System (ADS)

Boisvert, John; Steffen, Jason H.; Nelson, Benjamin E.

2018-01-01

Uncovering the architectures of planetary systems give insight into their formation and evolution. For example, the protoplanetary disk in multi-planet systems can drive adjacent planets into mean-motion resonances (such as the 2:1), while simultaneously damping their eccentricities. On the other hand, planet-planet scattering will produce single planets with eccentric orbits.In the RV signal, there is a degeneracy between models with two planets on circular orbits near the 2:1 period ratio and single planets on eccentric orbits. Historically, single planet models have been favored on simplicity grounds. However, the prominence of the 2:1 period ratio for systems observed by Kepler motivates additional scrutiny for single eccentric systems.We analyzed 95 planetary systems from the NASA Exoplanet Archive that are reported as single planet systems. We fit models of single eccentrics, circular doubles with a period ratio of 2:1, and circular doubles with a period ratio near 2.17:1 to the data. We computed the Bayes factors between each model in order to determine which is more likely given the current data. We find a significant fraction of these systems prefer double planet models. New observations are being planned to further break the degeneracy for these systems. This fraction suggests that disk-migration may be more important than the currently reported parameters propose.

Intracavity frequency doubling of a continuous wave Ti:sapphire ring laser and application in resonance Raman spectroscopy of heme protein dynamics

NASA Astrophysics Data System (ADS)

Buchter, Scott C.; Williams, Curtis; Schulte, Alfons; Alekel, Theodore, III; Mizell, Gregory J.; Fay, William R.

1995-04-01

Noncritical temperature-tuned phase-matching and large nonlinear coefficients make potassium niobate an attractive material for frequency doubling tuneable near-infrared radiation. We have mounted a KNbO3 crystal intracavity in an argon ion pumped, continuous wave Ti:Sapphire ring laser to increase the power level of the second harmonic. Wavelength selection at the fundamental frequency is accomplished with a birefringent filter. By using the crystal orientation that defines the d32 coefficient of KNbO3 we have obtained a blue second harmonic output tuneable from 425-445 nm. The laser is also characterized by the narrow linewidth of the Ti:Sapphire ring oscillator and good temporal stability. A continuous wave, frequency doubled Ti:sapphire laser is well suited to excite the resonance Raman spectrum in heme proteins with strong absorption bands in the range of 400 to 450 nm. We demonstrate the feasibility of such a setup for Raman studies of ligand binding to myoglobin. The Raman bands yield information on the reaction dynamics and on conformational changes near the linkage between the heme and the protein. In particular, a shift of the stretch frequency of the iron- histidine bond with high pressure may be attributed to a protein conformational change.

Double-spiral magnetic structure of the Fe/Cr multilayer revealed by nuclear resonance reflectivity

NASA Astrophysics Data System (ADS)

Andreeva, M. A.; Baulin, R. A.; Chumakov, A. I.; Rüffer, R.; Smirnov, G. V.; Babanov, Y. A.; Devyaterikov, D. I.; Milyaev, M. A.; Ponomarev, D. A.; Romashev, L. N.; Ustinov, V. V.

2018-01-01

We have studied the magnetization depth profiles in a [57Fe (dFe) /Cr (dCr) ]30 multilayer with ultrathin Fe layers and nominal thickness of the chromium spacers dCr≈2.0 nm using nuclear resonance scattering of synchrotron radiation. The presence of a broad pure-magnetic half-order (1/2) Bragg reflection has been detected at zero external field. The joint fit of the reflectivity curves and Mössbauer spectra of reflectivity measured near the critical angle and at the "magnetic" peak reveals that the magnetic structure of the multilayer is formed by two spirals, one in the odd and another one in the even iron layers, with the opposite signs of rotation. The double-spiral structure starts from the surface with the almost-antiferromagnetic alignment of the adjacent Fe layers. The rotation of the two spirals leads to nearly ferromagnetic alignment of the two magnetic subsystems at some depth, where the sudden turn of the magnetic vectors by ˜180∘ (spin flop) appears, and both spirals start to rotate in opposite directions. The observation of this unusual double-spiral magnetic structure suggests that the unique properties of giant magnetoresistance devices can be further tailored using ultrathin magnetic layers.

Generation of 369.4 nm Radiation by Efficient Doubling of a Diode Laser

NASA Technical Reports Server (NTRS)

Williams, A.; Seidel, D. J.; Maleki, J.

1993-01-01

A resonant cavity second harmonic generation system has been developed to produce 369.4 nm radiation from a 738.8 nm diode laser with 10 mW nominal output power. This system utilizes a polarization technique to lock the cavity to the laser frequency. In this paper we report on an evaluation of the system using a Titanium:Sapphire laser as the input source, and preliminary results with a diode laser source. To our knowledge, this is the deepest uv light ever produced by frequency-doubling a diode laser.