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Sample records for acoustic 4f imaging

  1. Photoacoustic tomography imaging using a 4f acoustic lens and peak-hold technology.

    PubMed

    Wei, Yadong; Tang, Zhilie; Zhang, Hanchao; He, Yongheng; Liu, Haifeng

    2008-04-14

    In this paper we present a new high-contrast photoacoustic tomography (PAT) imaging system using a 4f acoustic lens, a 64-element linear transducer array and peak-hold technology. This PAT imaging system has been developed to obtain three-dimensional (3D) PAT images of experimental samples. By utilizing a 4f acoustic lens, the photoacoustic (PA) signals generated from the sample are directly imaged on the imaging plane and collected by the 64-element linear transducer array, which changes them into the corresponding electronic signals. Then we can get one-dimensional (1D) images from the electronic signals using a peak detection-and-hold circuit. After vertical scanning with a stepping motor on the imaging plane, a 2D PA image of the sample is successfully obtained. Combined with the time-resolved technique, we can then get 3D PAT images. The results show that the reconstructed images agree well with the original samples. PMID:18542633

  2. Acoustic imaging system

    DOEpatents

    Smith, Richard W.

    1979-01-01

    An acoustic imaging system for displaying an object viewed by a moving array of transducers as the array is pivoted about a fixed point within a given plane. A plurality of transducers are fixedly positioned and equally spaced within a laterally extending array and operatively directed to transmit and receive acoustic signals along substantially parallel transmission paths. The transducers are sequentially activated along the array to transmit and receive acoustic signals according to a preestablished sequence. Means are provided for generating output voltages for each reception of an acoustic signal, corresponding to the coordinate position of the object viewed as the array is pivoted. Receptions from each of the transducers are presented on the same display at coordinates corresponding to the actual position of the object viewed to form a plane view of the object scanned.

  3. Electromagnetic acoustic imaging.

    PubMed

    Emerson, Jane F; Chang, David B; McNaughton, Stuart; Jeong, Jong Seob; Shung, K K; Cerwin, Stephen A

    2013-02-01

    Electromagnetic acoustic imaging (EMAI) is a new imaging technique that uses long-wavelength RF electromagnetic (EM) waves to induce ultrasound emission. Signal intensity and image contrast have been found to depend on spatially varying electrical conductivity of the medium in addition to conventional acoustic properties. The resultant conductivity- weighted ultrasound data may enhance the diagnostic performance of medical ultrasound in cancer and cardiovascular applications because of the known changes in conductivity of malignancy and blood-filled spaces. EMAI has a potential advantage over other related imaging techniques because it combines the high resolution associated with ultrasound detection with the generation of the ultrasound signals directly related to physiologically important electrical properties of the tissues. Here, we report the theoretical development of EMAI, implementation of a dual-mode EMAI/ultrasound apparatus, and successful demonstrations of EMAI in various phantoms designed to establish feasibility of the approach for eventual medical applications. PMID:23357910

  4. Acoustic subwavelength imaging of subsurface objects with acoustic resonant metalens

    SciTech Connect

    Cheng, Ying; Liu, XiaoJun; State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190 ; Zhou, Chen; Wei, Qi; Wu, DaJian

    2013-11-25

    Early research into acoustic metamaterials has shown the possibility of achieving subwavelength near-field acoustic imaging. However, a major restriction of acoustic metamaterials is that the imaging objects must be placed in close vicinity of the devices. Here, we present an approach for acoustic imaging of subsurface objects far below the diffraction limit. An acoustic metalens made of holey-structured metamaterials is used to magnify evanescent waves, which can rebuild an image at the central plane. Without changing the physical structure of the metalens, our proposed approach can image objects located at certain distances from the input surface, which provides subsurface signatures of the objects with subwavelength spatial resolution.

  5. Airborne synthetic aperture acoustic imaging.

    PubMed

    Soumekh, M

    1997-01-01

    This paper presents a system model and inversion for airborne synthetic aperture acoustic (SAA) imaging. The system model accurately represents the intercation of the acoustic source and the target region at near range values. Moreover, the model incorporates the fact that the relative speed of the vehicle's (transmitter/receiver) with respect to the target region is comparable to the acoustic wave propagation speed. The inversion utilizes the principle of spectral decomposition of spherical phase functions to develop a wavefront reconstruction method from SAA data. Processing issues and selection of appropriate acoustic FM-CW sources are discussed. Results are provided that exhibit the superior accuracy of the proposed SAA system model and inversion over their synthetic aperture radar (SAR) counterpart in which the vehicle's speed is assumed to be much smaller than the wave propagation speed. PMID:18282912

  6. Acoustic Waves in Medical Imaging and Diagnostics

    PubMed Central

    Sarvazyan, Armen P.; Urban, Matthew W.; Greenleaf, James F.

    2013-01-01

    Up until about two decades ago acoustic imaging and ultrasound imaging were synonymous. The term ultrasonography, or its abbreviated version sonography meant an imaging modality based on the use of ultrasonic compressional bulk waves. Since the 1990s numerous acoustic imaging modalities started to emerge based on the use of a different mode of acoustic wave: shear waves. It was demonstrated that imaging with these waves can provide very useful and very different information about the biological tissue being examined. We will discuss physical basis for the differences between these two basic modes of acoustic waves used in medical imaging and analyze the advantages associated with shear acoustic imaging. A comprehensive analysis of the range of acoustic wavelengths, velocities, and frequencies that have been used in different imaging applications will be presented. We will discuss the potential for future shear wave imaging applications. PMID:23643056

  7. Acoustic imaging microscope

    DOEpatents

    Deason, Vance A.; Telschow, Kenneth L.

    2006-10-17

    An imaging system includes: an object wavefront source and an optical microscope objective all positioned to direct an object wavefront onto an area of a vibrating subject surface encompassed by a field of view of the microscope objective, and to direct a modulated object wavefront reflected from the encompassed surface area through a photorefractive material; and a reference wavefront source and at least one phase modulator all positioned to direct a reference wavefront through the phase modulator and to direct a modulated reference wavefront from the phase modulator through the photorefractive material to interfere with the modulated object wavefront. The photorefractive material has a composition and a position such that interference of the modulated object wavefront and modulated reference wavefront occurs within the photorefractive material, providing a full-field, real-time image signal of the encompassed surface area.

  8. Reflective echo tomographic imaging using acoustic beams

    DOEpatents

    Kisner, Roger; Santos-Villalobos, Hector J

    2014-11-25

    An inspection system includes a plurality of acoustic beamformers, where each of the plurality of acoustic beamformers including a plurality of acoustic transmitter elements. The system also includes at least one controller configured for causing each of the plurality of acoustic beamformers to generate an acoustic beam directed to a point in a volume of interest during a first time. Based on a reflected wave intensity detected at a plurality of acoustic receiver elements, an image of the volume of interest can be generated.

  9. First images of thunder: Acoustic imaging of triggered lightning

    NASA Astrophysics Data System (ADS)

    Dayeh, M. A.; Evans, N. D.; Fuselier, S. A.; Trevino, J.; Ramaekers, J.; Dwyer, J. R.; Lucia, R.; Rassoul, H. K.; Kotovsky, D. A.; Jordan, D. M.; Uman, M. A.

    2015-07-01

    An acoustic camera comprising a linear microphone array is used to image the thunder signature of triggered lightning. Measurements were taken at the International Center for Lightning Research and Testing in Camp Blanding, FL, during the summer of 2014. The array was positioned in an end-fire orientation thus enabling the peak acoustic reception pattern to be steered vertically with a frequency-dependent spatial resolution. On 14 July 2014, a lightning event with nine return strokes was successfully triggered. We present the first acoustic images of individual return strokes at high frequencies (>1 kHz) and compare the acoustically inferred profile with optical images. We find (i) a strong correlation between the return stroke peak current and the radiated acoustic pressure and (ii) an acoustic signature from an M component current pulse with an unusual fast rise time. These results show that acoustic imaging enables clear identification and quantification of thunder sources as a function of lightning channel altitude.

  10. Acoustic 3D imaging of dental structures

    SciTech Connect

    Lewis, D.K.; Hume, W.R.; Douglass, G.D.

    1997-02-01

    Our goals for the first year of this three dimensional electodynamic imaging project was to determine how to combine flexible, individual addressable; preprocessing of array source signals; spectral extrapolation or received signals; acoustic tomography codes; and acoustic propagation modeling code. We investigated flexible, individually addressable acoustic array material to find the best match in power, sensitivity and cost and settled on PVDF sheet arrays and 3-1 composite material.

  11. Real-time imaging of acoustic rectification

    NASA Astrophysics Data System (ADS)

    Danworaphong, S.; Kelf, T. A.; Matsuda, O.; Tomoda, M.; Tanaka, Y.; Nishiguchi, N.; Wright, O. B.; Nishijima, Y.; Ueno, K.; Juodkazis, S.; Misawa, H.

    2011-11-01

    We image gigahertz surface acoustic waves normally incident on a microscopic linear array of triangular holesa generic "acoustic diode" geometrywith a real-time ultrafast optical technique. Spatiotemporal Fourier transforms reveal wave diffraction orders in k-space. Squared amplitude reflection and transmission coefficients for incidence on both sides of the array are evaluated and compared with numerical simulations. We thereby directly demonstrate acoustic rectification with an asymmetric structure.

  12. Pulsed-Source Interferometry in Acoustic Imaging

    NASA Technical Reports Server (NTRS)

    Shcheglov, Kirill; Gutierrez, Roman; Tang, Tony K.

    2003-01-01

    A combination of pulsed-source interferometry and acoustic diffraction has been proposed for use in imaging subsurface microscopic defects and other features in such diverse objects as integrated-circuit chips, specimens of materials, and mechanical parts. A specimen to be inspected by this technique would be mounted with its bottom side in contact with an acoustic transducer driven by a continuous-wave acoustic signal at a suitable frequency, which could be as low as a megahertz or as high as a few hundred gigahertz. The top side of the specimen would be coupled to an object that would have a flat (when not vibrating) top surface and that would serve as the acoustical analog of an optical medium (in effect, an acoustical "optic").

  13. Gauge Theory Formulation of Acoustical Imaging

    NASA Astrophysics Data System (ADS)

    Gan, W. S.

    There are many similarities between electromagnetic waves and sound waves. Maxwell's equation is the oldest gauge theory. Three main aspects of gauge theory are considered: (1) symmetries, (2) gauge invariance, (3) covariant form of the wave equation. Two of my discoveries mentioned in my earlier papers are revisited here: (1) symmetries of velocity field and stress field in the acoustic equations of motion, (2) a new stress field equation. Higher order Christoffel equation and higher order stress field equation are derived. The latter will form the basis of a new form of imaging the nonlinear elasticity imaging. The advantages of the application of gauge theory to acoustical imaging are mentioned.

  14. Imaging of Acoustic Waves in Sand

    SciTech Connect

    Deason, Vance Albert; Telschow, Kenneth Louis; Watson, Scott Marshall

    2003-08-01

    There is considerable interest in detecting objects such as landmines shallowly buried in loose earth or sand. Various techniques involving microwave, acoustic, thermal and magnetic sensors have been used to detect such objects. Acoustic and microwave sensors have shown promise, especially if used together. In most cases, the sensor package is scanned over an area to eventually build up an image or map of anomalies. We are proposing an alternate, acoustic method that directly provides an image of acoustic waves in sand or soil, and their interaction with buried objects. The INEEL Laser Ultrasonic Camera utilizes dynamic holography within photorefractive recording materials. This permits one to image and demodulate acoustic waves on surfaces in real time, without scanning. A video image is produced where intensity is directly and linearly proportional to surface motion. Both specular and diffusely reflecting surfaces can be accomodated and surface motion as small as 0.1 nm can be quantitatively detected. This system was used to directly image acoustic surface waves in sand as well as in solid objects. Waves as frequencies of 16 kHz were generated using modified acoustic speakers. These waves were directed through sand toward partially buried objects. The sand container was not on a vibration isolation table, but sat on the lab floor. Interaction of wavefronts with buried objects showed reflection, diffraction and interference effects that could provide clues to location and characteristics of buried objects. Although results are preliminary, success in this effort suggests that this method could be applied to detection of buried landmines or other near-surface items such as pipes and tanks.

  15. Underwater imaging with a moving acoustic lens.

    PubMed

    Kamgar-Parsi, B; Rosenblum, L J; Belcher, E O

    1998-01-01

    The acoustic lens is a high-resolution, forward-looking sonar for three dimensional (3-D) underwater imaging. We discuss processing the lens data for recreating and visualizing the scene. Acoustical imaging, compared to optical imaging, is sparse and low resolution. To achieve higher resolution, we obtain a denser sample by mounting the lens on a moving platform and passing over the scene. This introduces the problem of data fusion from multiple overlapping views for scene formation, which we discuss. We also discuss the improvements in object reconstruction by combining data from several passes over an object. We present algorithms for pass registration and show that this process can be done with enough accuracy to improve the image and provide greater detail about the object. The results of in-water experiments show the degree to which size and shape can be obtained under (nearly) ideal conditions. PMID:18267382

  16. Holographic imaging of surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Bruno, Franois; Laurent, Jrme; Royer, Daniel; Atlan, Michael

    2014-02-01

    We report on an experimental demonstration of surface acoustic waves monitoring on a thin metal plate with heterodyne optical holography. Narrowband imaging of local optical pathlength modulation is achieved with a frequency-tunable time-averaged laser Doppler holographic imaging scheme on a sensor array, at video-rate. This method enables robust and quantitative mapping of out-of-plane vibrations of nanometric amplitudes at radiofrequencies.

  17. Femtosecond imaging of nonlinear acoustics in gold.

    PubMed

    Pezeril, Thomas; Klieber, Christoph; Shalagatskyi, Viktor; Vaudel, Gwenaelle; Temnov, Vasily; Schmidt, Oliver G; Makarov, Denys

    2014-02-24

    We have developed a high-sensitivity, low-noise femtosecond imaging technique based on pump-probe time-resolved measurements with a standard CCD camera. The approach used in the experiment is based on lock-in acquisitions of images generated by a femtosecond laser probe synchronized to modulation of a femtosecond laser pump at the same rate. This technique allows time-resolved imaging of laser-excited phenomena with femtosecond time resolution. We illustrate the technique by time-resolved imaging of the nonlinear reshaping of a laser-excited picosecond acoustic pulse after propagation through a thin gold layer. Image analysis reveals the direct 2D visualization of the nonlinear acoustic propagation of the picosecond acoustic pulse. Many ultrafast pump-probe investigations can profit from this technique because of the wealth of information it provides over a typical single diode and lock-in amplifier setup, for example it can be used to image ultrasonic echoes in biological samples. PMID:24663778

  18. Real-time three-dimensional optoacoustic imaging using an acoustic lens system

    NASA Astrophysics Data System (ADS)

    Niederhauser, J. J.; Jaeger, M.; Frenz, M.

    2004-08-01

    In medical optoacoustics (photoacoustics), absorbing structures, such as blood vessels, hidden inside scattering media are illuminated with short laser pulses resulting in the generation of thermoelastic pressure transients. This initial three-dimensional (3D) acoustic pressure distribution, which exactly resembles the absorption distribution, was imaged into a water container with a 4f acoustic lens system. An optical dark-field stereo imaging system using a 30ns flash illumination light was used to capture a snapshot of the pressure-induced refraction index changes in the water container at a predetermined time after the original laser pulse. The imaging system works at 20Hz frame rate and was designed toward a theoretical resolution of 50?m. The proposed method directly provides 3D images of absorbing structures without the need of computational reconstruction algorithms.

  19. Determination of GaN solubility in supercritical ammonia with NH4F and NH4Cl mineralizer by in situ x-ray imaging of crystal dissolution

    NASA Astrophysics Data System (ADS)

    Schimmel, Saskia; Lindner, Michael; Steigerwald, Thomas G.; Hertweck, Benjamin; Richter, Theresia M. M.; Künecke, Ulrike; Alt, Nicolas S. A.; Niewa, Rainer; Schlücker, Eberhard; Wellmann, Peter J.

    2015-05-01

    Quantitative data on the solubility of GaN in supercritical ammonia using NH4F as mineralizer are reported. The solubility is determined by in situ x-ray imaging of the dissolution of GaN single crystals. First, solubility values obtained by this method with NH4Cl as mineralizer are presented and discussed with respect to existing literature data. Monitoring the dissolution process in situ reveals the time when the solubility limit is reached. Thus, it allows to distinguish the saturation of the solution from dissolution based on mass transport and deposition. This is a key advantage of solubility measurements by in situ x-ray imaging compared to gravimetric methods. Our results indicate that the solubility limit is reached much faster than usually assumed in gravimetric solubility studies and the solubility of GaN in ammonothermal media is significantly lower than reported so far.

  20. Acoustic imaging of objects buried in soil.

    PubMed

    Frazier, C H; Cadalli, N; Munson, D C; O'Brien, W D

    2000-07-01

    In this study, we demonstrate an acoustic system for high-resolution imaging of objects buried in soil. Our goal is to image cultural artifacts in order to assess in a rapid manner the historical significance of a potential construction site. We describe the imaging system and present preliminary images produced from data collected from a soil phantom. A mathematical model and associated computer software are developed in order to simulate the signals acquired by the system. We have built the imaging system, which incorporates a single element source transducer and a receiver array. The source and receiver array are moved together along a linear path to collect data. Using this system, we have obtained B-mode images of several targets by using delay-and-sum beamforming, and we have also applied synthetic aperture theory to this problem. PMID:10923879

  1. Acoustic Imaging of Snowpack Physical Properties

    NASA Astrophysics Data System (ADS)

    Kinar, N. J.; Pomeroy, J. W.

    2011-12-01

    Measurements of snowpack depth, density, structure and temperature have often been conducted by the use of snowpits and invasive measurement devices. Previous research has shown that acoustic waves passing through snow are capable of measuring these properties. An experimental observation device (SAS2, System for the Acoustic Sounding of Snow) was used to autonomously send audible sound waves into the top of the snowpack and to receive and process the waves reflected from the interior and bottom of the snowpack. A loudspeaker and microphone array separated by an offset distance was suspended in the air above the surface of the snowpack. Sound waves produced from a loudspeaker as frequency-swept sequences and maximum length sequences were used as source signals. Up to 24 microphones measured the audible signal from the snowpack. The signal-to-noise ratio was compared between sequences in the presence of environmental noise contributed by wind and reflections from vegetation. Beamforming algorithms were used to reject spurious reflections and to compensate for movement of the sensor assembly during the time of data collection. A custom-designed circuit with digital signal processing hardware implemented an inversion algorithm to relate the reflected sound wave data to snowpack physical properties and to create a two-dimensional image of snowpack stratigraphy. The low power consumption circuit was powered by batteries and through WiFi and Bluetooth interfaces enabled the display of processed data on a mobile device. Acoustic observations were logged to an SD card after each measurement. The SAS2 system was deployed at remote field locations in the Rocky Mountains of Alberta, Canada. Acoustic snow properties data was compared with data collected from gravimetric sampling, thermocouple arrays, radiometers and snowpit observations of density, stratigraphy and crystal structure. Aspects for further research and limitations of the acoustic sensing system are also discussed.

  2. Method and apparatus for acoustic imaging of objects in water

    DOEpatents

    Deason, Vance A.; Telschow, Kenneth L.

    2005-01-25

    A method, system and underwater camera for acoustic imaging of objects in water or other liquids includes an acoustic source for generating an acoustic wavefront for reflecting from a target object as a reflected wavefront. The reflected acoustic wavefront deforms a screen on an acoustic side and correspondingly deforms the opposing optical side of the screen. An optical processing system is optically coupled to the optical side of the screen and converts the deformations on the optical side of the screen into an optical intensity image of the target object.

  3. Interpreting Underwater Acoustic Images of the Upper Ocean Boundary Layer

    ERIC Educational Resources Information Center

    Ulloa, Marco J.

    2007-01-01

    A challenging task in physical studies of the upper ocean using underwater sound is the interpretation of high-resolution acoustic images. This paper covers a number of basic concepts necessary for undergraduate and postgraduate students to identify the most distinctive features of the images, providing a link with the acoustic signatures of

  4. Interpreting Underwater Acoustic Images of the Upper Ocean Boundary Layer

    ERIC Educational Resources Information Center

    Ulloa, Marco J.

    2007-01-01

    A challenging task in physical studies of the upper ocean using underwater sound is the interpretation of high-resolution acoustic images. This paper covers a number of basic concepts necessary for undergraduate and postgraduate students to identify the most distinctive features of the images, providing a link with the acoustic signatures of…

  5. Transthoracic Cardiac Acoustic Radiation Force Impulse Imaging

    NASA Astrophysics Data System (ADS)

    Bradway, David Pierson

    This dissertation investigates the feasibility of a real-time transthoracic Acoustic Radiation Force Impulse (ARFI) imaging system to measure myocardial function non-invasively in clinical setting. Heart failure is an important cardiovascular disease and contributes to the leading cause of death for developed countries. Patients exhibiting heart failure with a low left ventricular ejection fraction (LVEF) can often be identified by clinicians, but patients with preserved LVEF might be undetected if they do not exhibit other signs and symptoms of heart failure. These cases motivate development of transthoracic ARFI imaging to aid the early diagnosis of the structural and functional heart abnormalities leading to heart failure. M-Mode ARFI imaging utilizes ultrasonic radiation force to displace tissue several micrometers in the direction of wave propagation. Conventional ultrasound tracks the response of the tissue to the force. This measurement is repeated rapidly at a location through the cardiac cycle, measuring timing and relative changes in myocardial stiffness. ARFI imaging was previously shown capable of measuring myocardial properties and function via invasive open-chest and intracardiac approaches. The prototype imaging system described in this dissertation is capable of rapid acquisition, processing, and display of ARFI images and shear wave elasticity imaging (SWEI) movies. Also presented is a rigorous safety analysis, including finite element method (FEM) simulations of tissue heating, hydrophone intensity and mechanical index (MI) measurements, and thermocouple transducer face heating measurements. For the pulse sequences used in later animal and clinical studies, results from the safety analysis indicates that transthoracic ARFI imaging can be safely applied at rates and levels realizable on the prototype ARFI imaging system. Preliminary data are presented from in vivo trials studying changes in myocardial stiffness occurring under normal and abnormal heart function. Presented is the first use of transthoracic ARFI imaging in a serial study of heart failure in a porcine model. Results demonstrate the ability of transthoracic ARFI to image cyclically-varying stiffness changes in healthy and infarcted myocardium under good B-mode imaging conditions at depths in the range of 3-5 cm. Challenging imaging scenarios such as deep regions of interest, vigorous lateral motion and stable, reverberant clutter are analyzed and discussed. Results are then presented from the first study of clinical feasibility of transthoracic cardiac ARFI imaging. At the Duke University Medical Center, healthy volunteers and patients having magnetic resonance imaging-confirmed apical infarcts were enrolled for the study. The number of patients who met the inclusion criteria in this preliminary clinical trial was low, but results showed that the limitations seen in animal studies were not overcome by allowing transmit power levels to exceed the FDA mechanical index (MI) limit. The results suggested the primary source of image degradation was clutter rather than lack of radiation force. Additionally, the transthoracic method applied in its present form was not shown capable of tracking propagating ARFI-induced shear waves in the myocardium. Under current instrumentation and processing methods, results of these studies support feasibility for transthoracic ARFI in high-quality B-Mode imaging conditions. Transthoracic ARFI was not shown sensitive to infarct or to tracking heart failure in the presence of clutter and signal decorrelation. This work does provide evidence that transthoracic ARFI imaging is a safe non-invasive tool, but clinical efficacy as a diagnostic tool will need to be addressed by further development to overcome current challenges and increase robustness to sources of image degradation.

  6. Passive Imaging in Nondiffuse Acoustic Wavefields

    SciTech Connect

    Mulargia, Francesco; Castellaro, Silvia

    2008-05-30

    A main property of diffuse acoustic wavefields is that, taken any two points, each of them can be seen as the source of waves and the other as the recording station. This property is shown to follow simply from array azimuthal selectivity and Huygens principle in a locally isotropic wavefield. Without time reversal, this property holds approximately also in anisotropic azimuthally uniform wavefields, implying much looser constraints for undistorted passive imaging than those required by a diffuse field. A notable example is the seismic noise field, which is generally nondiffuse, but is found to be compatible with a finite aperture anisotropic uniform wavefield. The theoretical predictions were confirmed by an experiment on seismic noise in the mainland of Venice, Italy.

  7. Transient OH* Chemiluminescence Imaging of Acoustically Coupled Fuel Droplet Combustion

    NASA Astrophysics Data System (ADS)

    Wegener, Jeffrey; Sevilla, Cristhian; Smolke, Jennifer; Sung, Aaron; Chen, Kelvin; Smith, Owen; Karagozian, Ann

    2011-11-01

    This study focuses on combustion of liquid fuel droplets during exposure to external acoustic disturbances generated as standing waves within a closed acoustic waveguide. During such acoustic excitation, the mean flame orientation is observed to be dependent on the droplet's location relative to the pressure node (PN), and is consistent with the sign of a theoretical acoustic acceleration acting on the burning system. Yet experimentally estimated acoustic accelerations, measured from the degree of mean flame deflection, differ substantially in a quantitative sense from those predicted by theory.Phase-locked OH* chemiluminescence imaging reveals a deflected flame which oscillates in position relative to the droplet, with the largest degree of oscillation near the PN. A range of acoustic forcing frequencies and droplet locations are used to investigate flame movement over multiple acoustic cycles. The degree of flame oscillation, mean flame deflection angle, and fuel droplet burning rate all correlate with one another for different relative positions of the droplet. Supported by AFOSR.

  8. Optimization of a Biometric System Based on Acoustic Images

    PubMed Central

    Izquierdo Fuente, Alberto; Del Val Puente, Lara; Villacorta Calvo, Juan J.; Raboso Mateos, Mariano

    2014-01-01

    On the basis of an acoustic biometric system that captures 16 acoustic images of a person for 4 frequencies and 4 positions, a study was carried out to improve the performance of the system. On a first stage, an analysis to determine which images provide more information to the system was carried out showing that a set of 12 images allows the system to obtain results that are equivalent to using all of the 16 images. Finally, optimization techniques were used to obtain the set of weights associated with each acoustic image that maximizes the performance of the biometric system. These results improve significantly the performance of the preliminary system, while reducing the time of acquisition and computational burden, since the number of acoustic images was reduced. PMID:24616643

  9. Optimization of a biometric system based on acoustic images.

    PubMed

    Izquierdo Fuente, Alberto; Del Val Puente, Lara; Villacorta Calvo, Juan J; Raboso Mateos, Mariano

    2014-01-01

    On the basis of an acoustic biometric system that captures 16 acoustic images of a person for 4 frequencies and 4 positions, a study was carried out to improve the performance of the system. On a first stage, an analysis to determine which images provide more information to the system was carried out showing that a set of 12 images allows the system to obtain results that are equivalent to using all of the 16 images. Finally, optimization techniques were used to obtain the set of weights associated with each acoustic image that maximizes the performance of the biometric system. These results improve significantly the performance of the preliminary system, while reducing the time of acquisition and computational burden, since the number of acoustic images was reduced. PMID:24616643

  10. Image reconstruction in photoacoustic tomography involving layered acoustic media.

    PubMed

    Schoonover, Robert W; Anastasio, Mark A

    2011-06-01

    Photoacoustic tomography (PAT), also known as thermoacoustic or optoacoustic tomography, is a rapidly emerging biomedical imaging technique that combines optical image contrast with ultrasound detection principles. Most existing reconstruction algorithms for PAT assume the object of interest possesses homogeneous acoustic properties. The images produced by such algorithms can contain significant distortions and artifacts when the object's acoustic properties are spatially variant. In this work, we establish an image reconstruction formula for PAT applications in which a planar detection surface is employed and the to-be-imaged optical absorber is embedded in a known planar layered acoustic medium. The reconstruction formula is exact in a mathematical sense and accounts for multiple acoustic reflections between the layers of the medium. Computer-simulation studies are conducted to demonstrate and investigate the proposed method. PMID:21643397

  11. Acoustic Radiation Force Elasticity Imaging in Diagnostic Ultrasound

    PubMed Central

    Doherty, Joshua R.; Trahey, Gregg E.; Nightingale, Kathryn R.; Palmeri, Mark L.

    2013-01-01

    The development of ultrasound-based elasticity imaging methods has been the focus of intense research activity since the mid-1990s. In characterizing the mechanical properties of soft tissues, these techniques image an entirely new subset of tissue properties that cannot be derived with conventional ultrasound techniques. Clinically, tissue elasticity is known to be associated with pathological condition and with the ability to image these features in vivo, elasticity imaging methods may prove to be invaluable tools for the diagnosis and/or monitoring of disease. This review focuses on ultrasound-based elasticity imaging methods that generate an acoustic radiation force to induce tissue displacements. These methods can be performed non-invasively during routine exams to provide either qualitative or quantitative metrics of tissue elasticity. A brief overview of soft tissue mechanics relevant to elasticity imaging is provided, including a derivation of acoustic radiation force, and an overview of the various acoustic radiation force elasticity imaging methods. PMID:23549529

  12. Fracture analysis in borehole acoustic images using mathematical morphology

    NASA Astrophysics Data System (ADS)

    Xavier, Aldenize; Guerra, Carlos Eduardo; Andrade, André

    2015-06-01

    Fracture analysis is a geological task that treats so-called fracture attributes (location, direction (strike), slope (dip), and aperture) of the fractures that cross the borehole. It can be performed by direct measures on drill cores or interpreted on acoustic or electromagnetic images of the borehole wall. This activity has gained more importance in Brazil with the recent exploration of carbonate reservoirs of the Brazilian pre-salt. The acoustic imaging logging tool creates two images, the amplitude and the travel time. Only the amplitude image, which reflects the acoustic impedance of the borehole wall, is used to perform the fracture analysis. However, some misinterpretations may occur due to the qualitative nature of this interpretation being very dependent on the geologist’s expertise. Thus, we present a method of performing automation of the fracture analysis using acoustic amplitude images. This article is divided into two parts. In the first part, we present a mathematical model for the acoustic amplitude images along the borehole trajectory crossed by fractures. This model involves all fracture attributes in the generation of the images and is used to validate the results of fracture analysis. The second part presents the method for automatic fracture analysis. This method is composed of two stages. The first one performs fracture identification using an algorithm based on the mathematical morphology, which acts as an edge-detection tool that delimits the fracture region in the acoustic amplitude images. In the second stage, we apply an interpolating polynomial over the image region previously identified as fracture to extract the fracture attributes. The evaluation of this methodology is performed with synthetic images generated by the presented model that supports the results of the automatic fracture analysis performed using real acoustic amplitude images.

  13. Nondestructive imaging of shallow buried objects using acoustic computed tomography

    NASA Astrophysics Data System (ADS)

    Younis, Waheed A.; Stergiopoulos, Stergios; Havelock, David; Grodski, Julius

    2002-05-01

    The nondestructive three-dimensional acoustic tomography concept of the present investigation combines computerized tomography image reconstruction algorithms using acoustic diffracting waves together with depth information to produce a three-dimensional (3D) image of an underground section. The approach illuminates the underground area of interest with acoustic plane waves of frequencies 200-3000 Hz. For each transmitted pulse, the reflected-refracted signals are received by a line array of acoustic sensors located at a diametrically opposite point from the acoustic source line array. For a stratified underground medium and for a given depth, which is represented by a time delay in the received signal, a horizontal tomographic 2D image is reconstructed from the received projections. Integration of the depth dependent sequence of cross-sectional reconstructed images provides a complete three-dimensional overview of the inspected terrain. The method has been tested with an experimental system that consists of a line array of four-acoustic sources, providing plane waves, and a receiving line array of 32-acoustic sensors. The results indicate both the potential and the challenges facing the new methodology. Suggestions are made for improved performance, including an adaptive noise cancellation scheme and a numerical interpolation technique.

  14. Photoacoustic imaging using acoustic reflectors to enhance planar arrays.

    PubMed

    Ellwood, Robert; Zhang, Edward; Beard, Paul; Cox, Ben

    2014-12-01

    Planar sensor arrays have advantages when used for photoacoustic imaging: they do not require the imaging target to be enclosed, and they are easier to manufacture than curved arrays. However, planar arrays have a limited view of the acoustic field due to their finite size; therefore, not all of the acoustic waves emitted from a photoacoustic source can be recorded. This loss of data results in artifacts in the reconstructed photoacoustic image. A detection array configuration which combines a planar FabryProt sensor with perpendicular acoustic reflectors is described and experimentally implemented. This retains the detection advantages of the planar sensor while increasing the effective detection aperture in order to improve the reconstructed photoacoustic image. PMID:25535976

  15. Acoustic imaging in a water filled metallic pipe

    SciTech Connect

    Kolbe, W.F.; Turko, B.T.; Leskovar, B.

    1984-04-01

    A method is described for the imaging of the interior of a water filled metallic pipe using acoustical techniques. The apparatus consists of an array of 20 acoustic transducers mounted circumferentially around the pipe. Each transducer is pulsed in sequence, and the echos resulting from bubbles in the interior are digitized and processed by a computer to generate an image. The electronic control and digitizing system and the software processing of the echo signals are described. The performance of the apparatus is illustrated by the imaging of simulated bubbles consisting of thin walled glass spheres suspended in the pipe.

  16. Acoustic imaging in a water filled metallic pipe

    NASA Astrophysics Data System (ADS)

    Kolbe, W. F.; Turko, B. T.; Leskovar, B.

    1984-04-01

    A method is described for imaging the interior of a water filled metallic pipe using acoustical techniques. The apparatus consists of an array of 20 acoustic transducers mounted circumferentially around the pipe. Each transducer is pulsed in sequence, and the echos resulting from bubbles in the interior are digitized and processed by a computer to generate an image. The electronic control and digitizing system and the software processing of the echo signals are described. The performance of the apparatus is illustrated by the imaging of simulated bubbles consisting of thin walled glass spheres suspended in the pipe.

  17. Toward a laser-based noncontact acoustic land mine imager

    NASA Astrophysics Data System (ADS)

    DiMarzio, Charles A.; Li, Wen; Berg, Larry J.; Sabatier, James M.

    2000-08-01

    Acoustic sensing shows promise for the detection of buried landmines. One of us has previously demonstrated successful imaging of mine simulants buried at depths from the surface to 15 centimeters, using speakers and a laser vibrometer, which collects spectral data at low frequencies. The strength of the method is in the contrast between the porous soil and the nonporous mine, while the limitations are the strong attenuation of the probing acoustic wave and coupling of the sound directly into the vibrometer.

  18. Acoustic Radiation Force Impulse (ARFI) Imaging: a Review

    PubMed Central

    Nightingale, Kathy

    2012-01-01

    Acoustic radiation force based elasticity imaging methods are under investigation by many groups. These methods differ from traditional ultrasonic elasticity imaging methods in that they do not require compression of the transducer, and are thus expected to be less operator dependent. Methods have been developed that utilize impulsive (i.e. < 1 ms), harmonic (pulsed), and steady state radiation force excitations. The work discussed herein utilizes impulsive methods, for which two imaging approaches have been pursued: 1) monitoring the tissue response within the radiation force region of excitation (ROE) and generating images of relative differences in tissue stiffness (Acoustic Radiation Force Impulse (ARFI) imaging); and 2) monitoring the speed of shear wave propagation away from the ROE to quantify tissue stiffness (Shear Wave Elasticity Imaging (SWEI)). For these methods, a single ultrasound transducer on a commercial ultrasound system can be used to both generate acoustic radiation force in tissue, and to monitor the tissue displacement response. The response of tissue to this transient excitation is complicated and depends upon tissue geometry, radiation force field geometry, and tissue mechanical and acoustic properties. Higher shear wave speeds and smaller displacements are associated with stiffer tissues, and slower shear wave speeds and larger displacements occur with more compliant tissues. ARFI images have spatial resolution comparable to that of B-mode, often with greater contrast, providing matched, adjunctive information. SWEI images provide quantitative information about the tissue stiffness, typically with lower spatial resolution. A review these methods and examples of clinical applications are presented herein. PMID:22545033

  19. Acoustic-optical imaging without immersion

    NASA Technical Reports Server (NTRS)

    Liu, H.

    1979-01-01

    System using membraneous end wall of Bragg cell to separate test specimen from acoustic transmission medium, operates in real time and uses readily available optical components. System can be easily set up and maintained by people with little or no training in holography.

  20. Quantitative Determination of Lateral Mode Dispersion in Film Bulk Acoustic Resonators through Laser Acoustic Imaging

    SciTech Connect

    Ken Telschow; John D. Larson III

    2006-10-01

    Film Bulk Acoustic Resonators are useful for many signal processing applications. Detailed knowledge of their operation properties are needed to optimize their design for specific applications. The finite size of these resonators precludes their use in single acoustic modes; rather, multiple wave modes, such as, lateral wave modes are always excited concurrently. In order to determine the contributions of these modes, we have been using a newly developed full-field laser acoustic imaging approach to directly measure their amplitude and phase throughout the resonator. This paper describes new results comparing modeling of both elastic and piezoelectric effects in the active material with imaging measurement of all excited modes. Fourier transformation of the acoustic amplitude and phase displacement images provides a quantitative determination of excited mode amplitude and wavenumber at any frequency. Images combined at several frequencies form a direct visualization of lateral mode excitation and dispersion for the device under test allowing mode identification and comparison with predicted operational properties. Discussion and analysis are presented for modes near the first longitudinal thickness resonance (~900 MHz) in an AlN thin film resonator. Plate wave modeling, taking account of material crystalline orientation, elastic and piezoelectric properties and overlayer metallic films, will be discussed in relation to direct image measurements.

  1. Performance Evaluation of a Biometric System Based on Acoustic Images

    PubMed Central

    Izquierdo-Fuente, Alberto; del Val, Lara; Jiménez, María I.; Villacorta, Juan J.

    2011-01-01

    An acoustic electronic scanning array for acquiring images from a person using a biometric application is developed. Based on pulse-echo techniques, multifrequency acoustic images are obtained for a set of positions of a person (front, front with arms outstretched, back and side). Two Uniform Linear Arrays (ULA) with 15 λ/2-equispaced sensors have been employed, using different spatial apertures in order to reduce sidelobe levels. Working frequencies have been designed on the basis of the main lobe width, the grating lobe levels and the frequency responses of people and sensors. For a case-study with 10 people, the acoustic profiles, formed by all images acquired, are evaluated and compared in a mean square error sense. Finally, system performance, using False Match Rate (FMR)/False Non-Match Rate (FNMR) parameters and the Receiver Operating Characteristic (ROC) curve, is evaluated. On the basis of the obtained results, this system could be used for biometric applications. PMID:22163708

  2. Performance evaluation of a biometric system based on acoustic images.

    PubMed

    Izquierdo-Fuente, Alberto; del Val, Lara; Jiménez, María I; Villacorta, Juan J

    2011-01-01

    An acoustic electronic scanning array for acquiring images from a person using a biometric application is developed. Based on pulse-echo techniques, multifrequency acoustic images are obtained for a set of positions of a person (front, front with arms outstretched, back and side). Two Uniform Linear Arrays (ULA) with 15 λ/2-equispaced sensors have been employed, using different spatial apertures in order to reduce sidelobe levels. Working frequencies have been designed on the basis of the main lobe width, the grating lobe levels and the frequency responses of people and sensors. For a case-study with 10 people, the acoustic profiles, formed by all images acquired, are evaluated and compared in a mean square error sense. Finally, system performance, using False Match Rate (FMR)/False Non-Match Rate (FNMR) parameters and the Receiver Operating Characteristic (ROC) curve, is evaluated. On the basis of the obtained results, this system could be used for biometric applications. PMID:22163708

  3. Two-dimensional acoustic metamaterial structure for potential image processing

    NASA Astrophysics Data System (ADS)

    Sun, Hongwei; Han, Yu; Li, Ying; Pai, Frank

    2015-12-01

    This paper presents modeling, analysis techniques and experiment of for two-Dimensional Acoustic metamaterial Structure for filtering acoustic waves. For a unit cell of an infinite two-Dimensional Acoustic metamaterial Structure, governing equations are derived using the extended Hamilton principle. The concepts of negative effective mass and stiffness and how the spring-mass-damper subsystems create a stopband are explained in detail. Numerical simulations reveal that the actual working mechanism of the proposed acoustic metamaterial structure is based on the concept of conventional mechanical vibration absorbers. It uses the incoming wave in the structure to resonate the integrated membrane-mass-damper absorbers to vibrate in their optical mode at frequencies close to but above their local resonance frequencies to create shear forces and bending moments to straighten the panel and stop the wave propagation. Moreover, a two-dimension acoustic metamaterial structure consisting of lumped mass and elastic membrane is fabricated in the lab. We do experiments on the model and The results validate the concept and show that, for two-dimension acoustic metamaterial structure do exist two vibration modes. For the wave absorption, the mass of each cell should be considered in the design. With appropriate design calculations, the proposed two-dimension acoustic metamaterial structure can be used for absorption of low-frequency waves. Hence this special structure can be used in filtering the waves, and the potential using can increase the ultrasonic imaging quality.

  4. Laser Imaging of Airborne Acoustic Emission by Nonlinear Defects

    NASA Astrophysics Data System (ADS)

    Solodov, Igor; Dring, Daniel; Busse, Gerd

    2008-06-01

    Strongly nonlinear vibrations of near-surface fractured defects driven by an elastic wave radiate acoustic energy into adjacent air in a wide frequency range. The variations of pressure in the emitted airborne waves change the refractive index of air thus providing an acoustooptic interaction with a collimated laser beam. Such an air-coupled vibrometry (ACV) is proposed for detecting and imaging of acoustic radiation of nonlinear spectral components by cracked defects. The photoelastic relation in air is used to derive induced phase modulation of laser light in the heterodyne interferometer setup. The sensitivity of the scanning ACV to different spatial components of the acoustic radiation is analyzed. The animated airborne emission patterns are visualized for the higher harmonic and frequency mixing fields radiated by planar defects. The results confirm a high localization of the nonlinear acoustic emission around the defects and complicated directivity patterns appreciably different from those observed for fundamental frequencies.

  5. Optimal flushing agents for integrated optical and acoustic imaging systems.

    PubMed

    Li, Jiawen; Minami, Hataka; Steward, Earl; Ma, Teng; Mohar, Dilbahar; Robertson, Claire; Shung, Kirk; Zhou, Qifa; Patel, Pranav; Chen, Zhongping

    2015-05-01

    An increasing number of integrated optical and acoustic intravascular imaging systems have been developed and hold great promise for accurately diagnosing vulnerable plaques and guiding atherosclerosis treatment. However, in any intravascular environment, the vascular lumen is filled with blood, a high-scattering source for optical and high-frequency ultrasound signals. Blood must be flushed away to provide clearer images. To our knowledge, no research has been performed to find the ideal flushing agent for combined optical and acoustic imaging techniques. We selected three solutions as potential flushing agents for their image-enhancing effects: mannitol, dextran, and iohexol. Testing of these flushing agents was performed in a closed-loop circulation model and in vivo on rabbits. We found that a high concentration of dextran was the most useful for simultaneous intravascular ultrasound and optical coherence tomography imaging. PMID:25985096

  6. Optimal flushing agents for integrated optical and acoustic imaging systems

    NASA Astrophysics Data System (ADS)

    Li, Jiawen; Minami, Hataka; Steward, Earl; Ma, Teng; Mohar, Dilbahar; Robertson, Claire; Shung, Kirk; Zhou, Qifa; Patel, Pranav; Chen, Zhongping

    2015-05-01

    An increasing number of integrated optical and acoustic intravascular imaging systems have been developed and hold great promise for accurately diagnosing vulnerable plaques and guiding atherosclerosis treatment. However, in any intravascular environment, the vascular lumen is filled with blood, a high-scattering source for optical and high-frequency ultrasound signals. Blood must be flushed away to provide clearer images. To our knowledge, no research has been performed to find the ideal flushing agent for combined optical and acoustic imaging techniques. We selected three solutions as potential flushing agents for their image-enhancing effects: mannitol, dextran, and iohexol. Testing of these flushing agents was performed in a closed-loop circulation model and in vivo on rabbits. We found that a high concentration of dextran was the most useful for simultaneous intravascular ultrasound and optical coherence tomography imaging.

  7. Acoustic Molecular Imaging and Targeted Drug Delivery with Perfluorocarbon Nanoparticles

    NASA Astrophysics Data System (ADS)

    Lanza, Gregory M.; Hughes, Michael. S.; Marsh, Jon N.; Scott, Michael J.; Zhang, Huiying; Lacy, Elizabeth K.; Allen, John S.; Wickline, Samuel A.

    2005-03-01

    Advances in molecular biology and cellular biochemistry are providing new opportunities for diagnostic medical imaging to "see" beyond the anatomical manifestations of disease to the earliest biochemical signatures of disease. Liquid perfluorocarbon nanoparticles provide inherent acoustic contrast when bound to targets, e.g., fibrin deposits in a thrombus, but unbound nanoparticles are undetectable. This nanoparticle platform may be further functionalized with paramagnetic metals, such as gadolinium, or radionuclides, with homing ligands, like anti-αvβ3-integrins, and therapeutic agents. Acoustic imaging of densely distributed biomarkers, e.g., fibrin epitopes, is readily accommodated with fundamental imaging, but for sparse biomarkers, e.g., integrins, we have developed and implemented novel, nonlinear imaging techniques based upon information-theoretic receivers (i.e., thermodynamic receivers). These novel receivers allow sensitive direct imaging of contrast development.

  8. Epipolar geometry of opti-acoustic stereo imaging.

    PubMed

    Negahdaripour, Shahriar

    2007-10-01

    Optical and acoustic cameras are suitable imaging systems to inspect underwater structures, both in regular maintenance and security operations. Despite high resolution, optical systems have limited visibility range when deployed in turbid waters. In contrast, the new generation of high-frequency (MHz) acoustic cameras can provide images with enhanced target details in highly turbid waters, though their range is reduced by one to two orders of magnitude compared to traditional low-/midfrequency (10s-100s KHz) sonar systems. It is conceivable that an effective inspection strategy is the deployment of both optical and acoustic cameras on a submersible platform, to enable target imaging in a range of turbidity conditions. Under this scenario and where visibility allows, registration of the images from both cameras arranged in binocular stereo configuration provides valuable scene information that cannot be readily recovered from each sensor alone. We explore and derive the constraint equations for the epipolar geometry and stereo triangulation in utilizing these two sensing modalities with different projection models. Theoretical results supported by computer simulations show that an opti-acoustic stereo imaging system outperforms a traditional binocular vision with optical cameras, particularly for increasing target distance and (or) turbidity. PMID:17699922

  9. Breast imaging with acoustic tomography: a comparative study with MRI

    NASA Astrophysics Data System (ADS)

    Ranger, Bryan; Littrup, Peter; Duric, Neb; Li, Cuiping; Lupinacci, Jessica; Myc, Lukasz; Rama, Olsi; Bey-Knight, Lisa

    2009-02-01

    The objective of this study is to investigate a potential low-cost-alternative to MRI, based on acoustic tomography. Using MRI as the gold standard, our goals are to assess the performance of acoustic tomography in (i) depicting normal breast anatomy, (ii) imaging cancerous lesions and (iii) accentuating lesions relative to background tissue using thresholding techniques. Fifteen patients were imaged with MRI and with an acoustic tomography prototype. A qualitative visual comparison of the MRI and prototype images was used to verify anatomical similarities. These similarities suggest that the prototype can image fibrous stroma, parenchyma and fatty tissues, with similar sensitivity to MRI. The prototype was also shown to be able to image masses but equivalency in mass sensitivity with MRI could not be established because of the small numbers of patients and the prototype's limited scanning range. The range of thresholds required to establish tumor volume equivalency suggests that a universal threshold for isolating masses relative to background tissue is possible with acoustic tomography. Thresholding techniques promise to accentuate masses relative to background anatomy which may prove clinically useful in potential screening applications. Future work will utilize larger trials to verify these preliminary conclusions.

  10. Acoustic imaging for diagnostics of chemically reacting systems

    NASA Technical Reports Server (NTRS)

    Ramohalli, K.; Seshan, P.

    1983-01-01

    The concept of local diagnostics, in chemically reacting systems, with acoustic imaging is developed. The elements of acoustic imaging through ellipsoidal mirrors are theoretically discussed. In a general plan of the experimental program, the first system is chosen in these studies to be a simple open jet, non premixed turbulent flame. Methane is the fuel and enriched air is the oxidizer. This simple chemically reacting flow system is established at a Reynolds number (based on cold viscosity) of 50,000. A 1.5 m diameter high resolution acoustic mirror with an f-number of 0.75 is used to map the acoustic source zone along the axis of the flame. The results are presented as acoustic power spectra at various distances from the nozzle exit. It is seen that most of the reaction intensity is localized in a zone within 8 diameters from the exit. The bulk reactions (possibly around the periphery of the larger eddies) are evenly distributed along the length of the flame. Possibilities are seen for locally diagnosing single zones in a multiple cluster of reaction zones that occur frequently in practice. A brief outline is given of the future of this work which will be to apply this technique to chemically reacting flows not limited to combustion.

  11. Ideal flushing agents for integrated optical acoustic imaging systems

    NASA Astrophysics Data System (ADS)

    Li, Jiawen; Minami, Hataka; Steward, Earl; Ma, Teng; Mohar, Dilbahar; Robertson, Claire; Shung, K. Kirk; Zhou, Qifa; Patel, Pranav M.; Chen, Zhongping

    2015-02-01

    An increased number of integrated optical acoustic intravascular imaging systems have been researched and hold great hope for accurate diagnosing of vulnerable plaques and for guiding atherosclerosis treatment. However, in any intravascular environment, vascular lumen is filled with blood, which is a high-scattering source for optical and high frequency ultrasound signals. Blood must be flushed away to make images clear. To our knowledge, no research has been performed to find the ideal flushing agent that works for both optical and acoustic imaging techniques. We selected three solutions, mannitol, dextran and iohexol, as flushing agents because of their image-enhancing effects and low toxicities. Quantitative testing of these flushing agents was performed in a closed loop circulation model and in vivo on rabbits.

  12. COMBINED PHOTO-ACOUSTIC AND ACOUSTIC IMAGING OF HUMAN BREAST SPECIMENS IN THE MAMMOGRAPHIC GEOMETRY

    PubMed Central

    Xie, Zhixing; Hooi, Fong Ming; Fowlkes, J Brian; Pinsky, Renee W.; Wang, Xueding; Carson, Paul L.

    2013-01-01

    A photo-acoustic volume imaging (PAVI) system was designed to study breast cancer detection and diagnosis in the mammographic geometry in combination with automated 3-D ultrasound (AUS). The goal of the work described here was to validate the design and evaluate its performance in human breast tissues for non-invasive imaging of deeply positioned structures covering such geometry. The good penetration of nearinfrared light and high receiving sensitivity of a broad-bandwidth, 572-element, 2-D poly(vinyl difluoride) array at a low center frequency of 1 MHz were used with 20 channel simultaneous acquisition. Pseudo-lesions filled with dilute blood were imaged in three human breast specimens at various depths up to 49 mm. With near-infrared light illumination and 256-sample averaging, the extrapolated maximum depth in imaging a 2.4-mm blood-rich lesion with a 3-dB contrast-to-noise ratio in a compressed breast was 54 mm. Three-dimensional photo-acoustic volume image stacks of the breasts were co-registered with 3-D ultrasound image stacks, suggesting for the first time that PAVI, based on the intrinsic tissue contrast, can visualize tissue interfaces other than those with blood, including the inner skin surface and connective tissue sheets. With the designed system, PAVI revealed satisfactory imaging depth and sensitivity for coverage of the entire breast when imaged from both sides in the mammographic geometry with mild compression. PMID:23972486

  13. A Parallel Tracking Method for Acoustic Radiation Force Impulse Imaging

    PubMed Central

    Dahl, Jeremy J.; Pinton, Gianmarco F.; Mark, L; Agrawal, Vineet; Nightingale, Kathryn R.; Trahey, Gregg E.

    2007-01-01

    Radiation force-based techniques have been developed by several groups for imaging the mechanical properties of tissue. Acoustic Radiation Force Impulse (ARFI) imaging is one such method that uses commercially available scanners to generate localized radiation forces in tissue. The response of the tissue to the radiation force is determined using conventional B-mode imaging pulses to track micron-scale displacements in tissue. Current research in ARFI imaging is focused on producing real-time images of tissue displacements and related mechanical properties. Obstacles to producing a real-time ARFI imaging modality include data acquisition, processing power, data transfer rates, heating of the transducer, and patient safety concerns. We propose a parallel receive beamforming technique to reduce transducer heating and patient acoustic exposure, and to facilitate data acquisition for real-time ARFI imaging. Custom beam sequencing was used with a Siemens SONOLINE AntaresTM scanner to track tissue displacements with parallel-receive beam-forming in tissue-mimicking phantoms. Using simulations, the effects of material properties on parallel tracking are observed. Transducer and tissue heating for parallel tracking are compared to standard ARFI beam sequencing. The effects of tracking beam position and size of the tracked region are also discussed in relation to the size and temporal response of the region of applied force, and the impact on ARFI image contrast and signal-to-noise ratio are quantified. PMID:17328327

  14. Opto-acoustic breast imaging with co-registered ultrasound

    NASA Astrophysics Data System (ADS)

    Zalev, Jason; Clingman, Bryan; Herzog, Don; Miller, Tom; Stavros, A. Thomas; Oraevsky, Alexander; Kist, Kenneth; Dornbluth, N. Carol; Otto, Pamela

    2014-03-01

    We present results from a recent study involving the ImagioTM breast imaging system, which produces fused real-time two-dimensional color-coded opto-acoustic (OA) images that are co-registered and temporally inter- leaved with real-time gray scale ultrasound using a specialized duplex handheld probe. The use of dual optical wavelengths provides functional blood map images of breast tissue and tumors displayed with high contrast based on total hemoglobin and oxygen saturation of the blood. This provides functional diagnostic information pertaining to tumor metabolism. OA also shows morphologic information about tumor neo-vascularity that is complementary to the morphological information obtained with conventional gray scale ultrasound. This fusion technology conveniently enables real-time analysis of the functional opto-acoustic features of lesions detected by readers familiar with anatomical gray scale ultrasound. We demonstrate co-registered opto-acoustic and ultrasonic images of malignant and benign tumors from a recent clinical study that provide new insight into the function of tumors in-vivo. Results from the Feasibility Study show preliminary evidence that the technology may have the capability to improve characterization of benign and malignant breast masses over conventional diagnostic breast ultrasound alone and to improve overall accuracy of breast mass diagnosis. In particular, OA improved speci city over that of conventional diagnostic ultrasound, which could potentially reduce the number of negative biopsies performed without missing cancers.

  15. Near-Field Imaging with Sound: An Acoustic STM Model

    NASA Astrophysics Data System (ADS)

    Euler, Manfred

    2012-10-01

    The invention of scanning tunneling microscopy (STM) 30 years ago opened up a visual window to the nano-world and sparked off a bunch of new methods for investigating and controlling matter and its transformations at the atomic and molecular level. However, an adequate theoretical understanding of the method is demanding; STM images can be considered quantum theory condensed into a pictorial representation. A hands-on model is presented for demonstrating the imaging principles in introductory teaching. It uses sound waves and computer visualization to create mappings of acoustic resonators. The macroscopic simile is made possible by quantum-classical analogies between matter and sound waves. Grounding STM in acoustic experience may help to make the underlying quantum concepts such as tunneling less abstract to students.

  16. Ultra high frequency imaging acoustic microscope

    DOEpatents

    Deason, Vance A.; Telschow, Kenneth L.

    2006-05-23

    An imaging system includes: an object wavefront source and an optical microscope objective all positioned to direct an object wavefront onto an area of a vibrating subject surface encompassed by a field of view of the microscope objective, and to direct a modulated object wavefront reflected from the encompassed surface area through a photorefractive material; and a reference wavefront source and at least one phase modulator all positioned to direct a reference wavefront through the phase modulator and to direct a modulated reference wavefront from the phase modulator through the photorefractive material to interfere with the modulated object wavefront. The photorefractive material has a composition and a position such that interference of the modulated object wavefront and modulated reference wavefront occurs within the photorefractive material, providing a full-field, real-time image signal of the encompassed surface area.

  17. Identifying Vulnerable Plaques with Acoustic Radiation Force Impulse Imaging

    NASA Astrophysics Data System (ADS)

    Doherty, Joshua Ryan

    The rupture of arterial plaques is the most common cause of ischemic complications including stroke, the fourth leading cause of death and number one cause of long term disability in the United States. Unfortunately, because conventional diagnostic tools fail to identify plaques that confer the highest risk, often a disabling stroke and/or sudden death is the first sign of disease. A diagnostic method capable of characterizing plaque vulnerability would likely enhance the predictive ability and ultimately the treatment of stroke before the onset of clinical events. This dissertation evaluates the hypothesis that Acoustic Radiation Force Impulse (ARFI) imaging can noninvasively identify lipid regions, that have been shown to increase a plaque's propensity to rupture, within carotid artery plaques in vivo. The work detailed herein describes development efforts and results from simulations and experiments that were performed to evaluate this hypothesis. To first demonstrate feasibility and evaluate potential safety concerns, finite- element method simulations are used to model the response of carotid artery plaques to an acoustic radiation force excitation. Lipid pool visualization is shown to vary as a function of lipid pool geometry and stiffness. A comparison of the resulting Von Mises stresses indicates that stresses induced by an ARFI excitation are three orders of magnitude lower than those induced by blood pressure. This thesis also presents the development of a novel pulse inversion harmonic tracking method to reduce clutter-imposed errors in ultrasound-based tissue displacement estimates. This method is validated in phantoms and was found to reduce bias and jitter displacement errors for a marked improvement in image quality in vivo. Lastly, this dissertation presents results from a preliminary in vivo study that compares ARFI imaging derived plaque stiffness with spatially registered composition determined by a Magnetic Resonance Imaging (MRI) gold standard in human carotid artery plaques. It is shown in this capstone experiment that lipid filled regions in MRI correspond to areas of increased displacement in ARFI imaging while calcium and loose matrix components in MRI correspond to uniformly low displacements in ARFI imaging. This dissertation provides evidence to support that ARFI imaging may provide important prognostic and diagnostic information regarding stroke risk via measurements of plaque stiffness. More generally, the results have important implications for all acoustic radiation force based imaging methods used clinically.

  18. Nonlinear acoustic time reversal imaging using the scaling subtraction method

    NASA Astrophysics Data System (ADS)

    Scalerandi, M.; Gliozzi, A. S.; Bruno, C. L. E.; Van Den Abeele, K.

    2008-11-01

    Lab experiments have shown that the imaging of nonlinear scatterers using time reversal acoustics can be a very promising tool for early stage damage detection. The potential applications are however limited by the need for an extremely accurate acquisition system. In order to let nonlinear features emerge from the background noise it is necessary to enhance the signal-to-noise ratio as much as possible. A comprehensive analysis to determine the nonlinear components in a recorded time signal, an alternative to those usually adopted (e.g. fast Fourier), is proposed here. The method is based on the nonlinear physical properties of the solution of the wave equation and takes advantage of the deficient system response scalability with the excitation amplitude. In this contribution, we outline the adopted procedure and apply it to a nonlinear time reversal imaging simulation to highlight the advantages with respect to traditional imaging based on a fast Fourier analysis of the recorded signals.

  19. Feasibility of High Frequency Acoustic Imaging for Inspection of Containments

    SciTech Connect

    C.N. Corrado; J.E. Bondaryk; V. Godino

    1998-08-01

    The Nuclear Regulatory Commission has a program at the Oak Ridge National Laboratory to provide assistance in their assessment of the effects of potential degradation on the structural integrity and Ieaktightness of metal containment vessels and steel liners of concrete containment in nuclear power plants. One of the program objectives is to identify a technique(s) for inspection of inaccessible portions of the containment pressure boundary. Acoustic imaging has been identified as one of these potential techniques. A numerical feasibility study investigated the use of high-frequency bistatic acoustic imaging techniques for inspection of inaccessible portions of the metallic pressure boundary of nuclear power plant containment. The range-dependent version of the OASES Code developed at the Massachusetts Institute of Technology was utilized to perform a series of numerical simulations. OASES is a well developed and extensively tested code for evaluation of the acoustic field in a system of stratified fluid and/or elastic layers. Using the code, an arbitrary number of fluid or solid elastic layers are interleaved, with the outer layers modeled as halfspaces. High frequency vibrational sources were modeled to simulate elastic waves in the steel. The received field due to an arbitrary source array can be calculated at arbitrary depth and range positions. In this numerical study, waves that reflect and scatter from surface roughness caused by modeled degradations (e.g., corrosion) are detected and used to identify and map the steel degradation. Variables in the numerical study included frequency, flaw size, interrogation distance, and sensor incident angle.Based on these analytical simulations, it is considered unlikely that acoustic imaging technology can be used to investigate embedded steel liners of reinforced concrete containment. The thin steel liner and high signal losses to the concrete make this application difficult. Results for portions of steel containment embedded in concrete are more encouraging in that they indicate that the intrinsic backscatter from degradations representing thickness reductions from 10 to 80% the shell thickness are sufficient to permit detection. It is recommended that a controlled experimental program be conducted in which sensor levels are calibrated against degradations to determine if current sensor technology can input sufficient power into the system to provide return levels within the dynamic range of the receivers.

  20. Multi-crack imaging using nonclassical nonlinear acoustic method

    NASA Astrophysics Data System (ADS)

    Zhang, Lue; Zhang, Ying; Liu, Xiao-Zhou; Gong, Xiu-Fen

    2014-10-01

    Solid materials with cracks exhibit the nonclassical nonlinear acoustical behavior. The micro-defects in solid materials can be detected by nonlinear elastic wave spectroscopy (NEWS) method with a time-reversal (TR) mirror. While defects lie in viscoelastic solid material with different distances from one another, the nonlinear and hysteretic stress—strain relation is established with Preisach—Mayergoyz (PM) model in crack zone. Pulse inversion (PI) and TR methods are used in numerical simulation and defect locations can be determined from images obtained by the maximum value. Since false-positive defects might appear and degrade the imaging when the defects are located quite closely, the maximum value imaging with a time window is introduced to analyze how defects affect each other and how the fake one occurs. Furthermore, NEWS-TR-NEWS method is put forward to improve NEWS-TR scheme, with another forward propagation (NEWS) added to the existing phases (NEWS and TR). In the added phase, scanner locations are determined by locations of all defects imaged in previous phases, so that whether an imaged defect is real can be deduced. NEWS-TR-NEWS method is proved to be effective to distinguish real defects from the false-positive ones. Moreover, it is also helpful to detect the crack that is weaker than others during imaging procedure.

  1. An acoustic charge transport imager for high definition television applications

    NASA Technical Reports Server (NTRS)

    Hunt, W. D.; Brennan, Kevin F.

    1994-01-01

    The primary goal of this research is to develop a solid-state high definition television (HDTV) imager chip operating at a frame rate of about 170 frames/sec at 2 Megapixels per frame. This imager offers an order of magnitude improvement in speed over CCD designs and will allow for monolithic imagers operating from the IR to the UV. The technical approach of the project focuses on the development of the three basic components of the imager and their integration. The imager chip can be divided into three distinct components: (1) image capture via an array of avalanche photodiodes (APD's), (2) charge collection, storage and overflow control via a charge transfer transistor device (CTD), and (3) charge readout via an array of acoustic charge transport (ACT) channels. The use of APD's allows for front end gain at low noise and low operating voltages while the ACT readout enables concomitant high speed and high charge transfer efficiency. Currently work is progressing towards the development of manufacturable designs for each of these component devices. In addition to the development of each of the three distinct components, work towards their integration is also progressing. The component designs are considered not only to meet individual specifications but to provide overall system level performance suitable for HDTV operation upon integration. The ultimate manufacturability and reliability of the chip constrains the design as well. The progress made during this period is described in detail in Sections 2-4.

  2. Fast transforms for acoustic imaging--part II: applications.

    PubMed

    Ribeiro, Flávio P; Nascimento, Vítor H

    2011-08-01

    In Part I ["Fast Transforms for Acoustic Imaging-Part I: Theory," IEEE Transactions on Image Processing], we introduced the Kronecker array transform (KAT), a fast transform for imaging with separable arrays. Given a source distribution, the KAT produces the spectral matrix which would be measured by a separable sensor array. In Part II, we establish connections between the KAT, beamforming and 2-D convolutions, and show how these results can be used to accelerate classical and state of the art array imaging algorithms. We also propose using the KAT to accelerate general purpose regularized least-squares solvers. Using this approach, we avoid ill-conditioned deconvolution steps and obtain more accurate reconstructions than previously possible, while maintaining low computational costs. We also show how the KAT performs when imaging near-field source distributions, and illustrate the trade-off between accuracy and computational complexity. Finally, we show that separable designs can deliver accuracy competitive with multi-arm logarithmic spiral geometries, while having the computational advantages of the KAT. PMID:21342849

  3. An acoustic charge transport imager for high definition television applications

    NASA Technical Reports Server (NTRS)

    Hunt, W. D.; Brennan, K. F.; Summers, C. J.

    1994-01-01

    The primary goal of this research is to develop a solid-state television (HDTV) imager chip operating at a frame rate of about 170 frames/sec at 2 Megapixels/frame. This imager will offer an order of magnitude improvements in speed over CCD designs and will allow for monolithic imagers operating from the IR to UV. The technical approach of the project focuses on the development of the three basic components of the imager and their subsequent integration. The camera chip can be divided into three distinct functions: (1) image capture via an array of avalanche photodiodes (APD's); (2) charge collection, storage, and overflow control via a charge transfer transistor device (CTD); and (3) charge readout via an array of acoustic charge transport (ACT) channels. The use of APD's allows for front end gain at low noise and low operating voltages while the ACT readout enables concomitant high speed and high charge transfer efficiency. Currently work is progressing towards the optimization of each of these component devices. In addition to the development of each of the three distinct components, work towards their integration and manufacturability is also progressing. The component designs are considered not only to meet individual specifications but to provide overall system level performance suitable for HDTV operation upon integration. The ultimate manufacturability and reliability of the chip constrains the design as well. The progress made during this period is described in detail.

  4. Imaging surface acoustic waves in anisotropic and periodic media

    NASA Astrophysics Data System (ADS)

    Vines, Robert Ellsworth

    A new technique has been developed for studying surface acoustic wave propagation. The technique, which uses non- contact immersion transducers to excite and detect ultrasound with frequencies between 1 and 20 MHz, allows convenient examination of surface waves traveling in arbitrary directions on a sample. Coupling the easy scanning of ultrasound propagation with time- resolved detection of the surface-wave amplitude makes this method particularly suited to examining anisotropic materials. The first section of this thesis deals with surface waves on crystals and other homogeneous solids. The general theory describing surface-wave behavior on anisotropic materials is adapted to our technique. In anisotropic materials, two types of surface waves, designated Rayleigh surface waves and pseudo-surface waves, satisfy the boundary conditions for a free surface. The experimental design is then described, and images obtained on a variety of crystalline samples are examined. Discrepancies between the calculations and the observed results have led to an investigation of the effects of fluid loading on the surface waves. It is found that coupling between the surface waves and the loading liquid will attenuate the propagating surface waves, with high frequencies showing stronger attenuation. In addition, the loading will affect the velocities of the surface waves, and in some cases will support additional surface-wave modes. The remainder of the thesis examines surface-wave propagation on a variety of periodic structures. Carbon- fiber/epoxy composites are first examined, and the elastic properties of a homogeneous sample are used to determine the surface-wave velocities of layered samples in the long-wavelength limit. Two systems are then examined in the dispersive regime, where the wavelength of the surface waves is comparable to the periodicity of the sample. The first, a multilayer sample constructed from layers of aluminum and a low-density polymer, has one-dimensional symmetry. Calculations of the acoustic band structure for acoustic waves traveling in this material, and the resulting surface-wave profiles, are compared to the experimental results. Analysis of this sample is complicated by total internal reflection, which occurs at the composite/aluminum interface for a range of propagation directions. The second sample studied is a two-dimensional lattice with hexagonal symmetry. Calculations of surface-wave propagation in this type of sample show that, for certain combinations of materials, a complete acoustic band gap can be obtained. Experiments performed on two samples with this geometry are then compared to the expected surface-wave behavior on these structures.

  5. Detection of Landmines from Acoustic Images Based on Cepstral Coefficients

    NASA Astrophysics Data System (ADS)

    Abd El-Samie, Fathi E.

    2009-12-01

    This paper introduces a cepstral approach for the automatic detection of landmines from acoustic images. This approach is based on treating the problem of landmine detection as a pattern recognition problem. Cepstral features are extracted from a group of landmine images which are transformed first to 1-D signals by lexicographic ordering. Mel frequency cepstral coefficients (MFCCs) and polynomial shaping coefficients are extracted from these 1-D signals to form a database of features, which can be used to train a neural network with the landmine features. The landmine detection can be performed by extracting features from any new image with the same method used in the training phase. These features are tested with the neural network to decide whether a landmine exists or not. The different domains are tested and compared for efficient feature extraction from the lexicographically ordered 1-D signals. Experimental results show the success of the proposed cepstral approach for landmine detection at low as well as high signal to noise ratios. Results also show that the discrete cosine transform is the most appropriate domain for feature extraction.

  6. Liver ablation guidance with acoustic radiation force impulse imaging

    PubMed Central

    Fahey, B J; Hsu, S J; Wolf, P D; Nelson, R C; Trahey, G E

    2008-01-01

    Previous studies have established the feasibility of monitoring radiofrequency (RF) ablation procedures with acoustic radiation force impulse (ARFI) imaging. However, questions remained regarding the utility of the technique in clinically realistic scenarios and at scanning depths associated with abdominal imaging in adults. We address several of these issues and detail recent progress towards the clinical relevance of the ARFI technique. Results from in vitro bovine tissues and an in vivo ovine model are presented. Additional experiments were conducted with a tissue-mimicking phantom and parallel receive tracking techniques in order to further support the clinical feasibility of the method. Thermal lesions created during RF ablation are visualized with high contrast in both in vitro and in vivo hepatic tissues, and radial lesion growth can be monitored throughout the duration of the procedure. ARFI imaging is implemented on a diagnostic ultrasonic scanner, and thus may be a convenient option to guide RF ablation procedures, particularly when electrode insertion is also performed with sonographic guidance. PMID:16861781

  7. Standing tree decay detection by using acoustic tomography images

    NASA Astrophysics Data System (ADS)

    Espinosa, Luis F.; Arciniegas, Andres F.; Prieto, Flavio A.; Cortes, Yolima; Brancheriau, Loïc.

    2015-04-01

    The acoustic tomographic technique is used in the diagnosis process of standing trees. This paper presents a segmentation methodology to separate defective regions in cross-section tomographic images obtained with Arbotom® device. A set of experiments was proposed using two trunk samples obtained from a eucalyptus tree, simulating defects by drilling holes with known geometry, size and position and using different number of sensors. Also, tomographic images from trees presenting real defects were studied, by testing two different species with significant internal decay. Tomographic images and photographs from the trunk cross-section were processed to align the propagation velocity data with a corresponding region, healthy or defective. The segmentation was performed by finding a velocity threshold value to separate the defective region; a logistic regression model was fitted to obtain the value that maximizes a performance criterion, being selected the geometric mean. Accuracy segmentation values increased as the number of sensors augmented; also the position influenced the result, obtaining improved results in the case of centric defects.

  8. Imaging Performance Evaluation Method of Wide-View Underwater Acoustic Lens by Geometrical Skew Ray Analysis

    NASA Astrophysics Data System (ADS)

    Sayuri Matsumoto,; Norihide Takeyama,; Takenobu Tsuchiya,; Nobuyuki Endoh,

    2010-07-01

    In the image formation performance of an underwater acoustic lens, the use of geometrical skew ray analysis for usually use in optical lens design field was examined. We measured acoustic pressure fields through a single lens, from which the acoustic energy distribution was obtained by using encircled energy. On the other hand, the analyzed acoustic energy distribution was evaluated by geometrical skew ray analysis under the measurement condition including the apodization of the source and effect of water temperature. We compared the measured and analyzed convergence positions, which the diameter of 80% of total amount of acoustic energy is the minimum. Then the both convergence positions correspond. As a result, it was shown that the image performance evaluation of a wide-view acoustic lens by geometrical skew ray analysis is useful.

  9. Acoustic-integrated dynamic MR imaging for a patient with obstructive sleep apnea.

    PubMed

    Chen, Yunn-Jy; Shih, Tiffany Ting-Fang; Chang, Yi-Chung; Hsu, Ying-Chieh; Huon, Leh-Kiong; Lo, Men-Tzung; Pham, Van-Truong; Lin, Chen; Wang, Pa-Chun

    2015-12-01

    Obstructive sleep apnea syndrome (OSAS) is caused by multi-level upper airway obstruction. Anatomic changes at the sites of obstruction may modify the physical or acoustic properties of snores. The surgical success of OSA depends upon precise localization of obstructed levels. We present a case of OSAS who received simultaneous dynamic MRI and snore acoustic recordings. The synchronized image and acoustic information successfully characterize the sites of temporal obstruction during sleep-disordered breathing events. PMID:26278970

  10. Dual-frequency acoustic droplet vaporization detection for medical imaging.

    PubMed

    Arena, Christopher B; Novell, Anthony; Sheeran, Paul S; Puett, Connor; Moyer, Linsey C; Dayton, Paul A

    2015-09-01

    Liquid-filled perfluorocarbon droplets emit a unique acoustic signature when vaporized into gas-filled microbubbles using ultrasound. Here, we conducted a pilot study in a tissue-mimicking flow phantom to explore the spatial aspects of droplet vaporization and investigate the effects of applied pressure and droplet concentration on image contrast and axial and lateral resolution. Control microbubble contrast agents were used for comparison. A confocal dual-frequency transducer was used to transmit at 8 MHz and passively receive at 1 MHz. Droplet signals were of significantly higher energy than microbubble signals. This resulted in improved signal separation and high contrast-to-tissue ratios (CTR). Specifically, with a peak negative pressure (PNP) of 450 kPa applied at the focus, the CTR of B-mode images was 18.3 dB for droplets and -0.4 for microbubbles. The lateral resolution was dictated by the size of the droplet activation area, with lower pressures resulting in smaller activation areas and improved lateral resolution (0.67 mm at 450 kPa). The axial resolution in droplet images was dictated by the size of the initial droplet and was independent of the properties of the transmit pulse (3.86 mm at 450 kPa). In post-processing, time-domain averaging (TDA) improved droplet and microbubble signal separation at high pressures (640 kPa and 700 kPa). Taken together, these results indicate that it is possible to generate high-sensitivity, high-contrast images of vaporization events. In the future, this has the potential to be applied in combination with droplet-mediated therapy to track treatment outcomes or as a standalone diagnostic system to monitor the physical properties of the surrounding environment. PMID:26415125

  11. MR imaging of the acoustic nerves and small acoustic neuromas at 0.6 T: prospective study.

    PubMed

    New, P F; Bachow, T B; Wismer, G L; Rosen, B R; Brady, T J

    1985-05-01

    To evaluate the capability of magnetic resonance (MR) in imaging normal acoustic nerves, 12 volunteers without signs or symptoms of intracranial disease were examined using a 0.6 T superconductive system. Several spin-echo (SE) pulse sequences were tested to identify the optimal sequence for demonstration of the acoustic nerve bundle. Repetition times (TRs) varied from 300 to 2000 msec and echo times (TEs) from 30 to 120 msec. A single-slice technique was used with 5 and 8 mm sections, one or two data acquisitions per projection, and axial and coronal imaging. The normal acoustic nerves were demonstrated readily by MR in axial and/or coronal sections. The distal parts of the nerves and tumors were imaged best with SE 1500/60. The medial extremities of the seventh and eighth nerves tended to be obscured in this sequence by brightening the cerebrospinal fluid signal adjacent to the brainstem, but they were demonstrated clearly with 500 or 800 msec TR and 30 msec TE. Five patients were studied who had hearing loss and evidence of retrocochlear disease. In four patients, MR imaging demonstrated five acoustic nerve tumors ranging in size from purely intracanalicular to a 12 mm cisternal component. In the fifth case, no tumor was identified by MR imaging or gas computed tomographic (CT) cisternography. Contrast-enhanced CT using a Siemens Somatom DR 3 or GE CT/T 8800 scanner failed to provide convincing evidence of tumor in any case, while gas CT cisternography was positive in all five tumors. All five acoustic neuromas were identified readily using the SE sequences that proved optimal for demonstration of normal nerves. This experience revealed that MR imaging can demonstrate the eighth nerve complex well and reliably. Single-slice (5 or 8 mm) technique is adequate, but multislice without tissue gaps (used recently) is more efficient. Small, even intracanalicular, acoustic neuromas are imaged effectively, indicating that the method is capable of superseding contrast CT cisternography, particularly with improving technology. PMID:3920871

  12. Full-Field Imaging of Acoustic Motion at Nanosecond Time and Micron Length Scales

    SciTech Connect

    Telschow, Kenneth Louis; Deason, Vance Albert; Cottle, David Lynn; Larson III, John D.

    2002-10-01

    A full-field view laser ultrasonic imaging method has been developed that measures acoustic motion at a surface without scanning. Images are recorded at normal video frame rates by employing dynamic holography using photorefractive interferometric detection. By extending the approach to ultra high frequencies, an acoustic microscope has been developed capable of operation on the nanosecond time and micron length scales. Both acoustic amplitude and phase are recorded allowing full calibration and determination of phases to within a single arbitrary constant. Results are presented of measurements at frequencies at 800-900 MHz illustrating a multitude of normal mode behavior in electrically driven thin film acoustic resonators. Coupled with microwave electrical impedance measurements, this imaging mode provides an exceptionally fast method for evaluation of electric to acoustic coupling and performance of these devices. Images of 256x240 pixels are recorded at 18Hz rates synchronized to obtain both in-phase and quadrature detection of the acoustic motion. Simple averaging provides sensitivity to the subnanometer level calibrated over the image using interferometry. Identification of specific acoustic modes and their relationship to electrical impedance characteristics show the advantages and overall high speed of the technique.

  13. Acoustic multimode interference and self-imaging phenomena realized in multimodal phononic crystal waveguides

    NASA Astrophysics Data System (ADS)

    Zou, Qiushun; Yu, Tianbao; Liu, Jiangtao; Liu, Nianhua; Wang, Tongbiao; Liao, Qinghua

    2015-09-01

    We report an acoustic multimode interference effect and self-imaging phenomena in an acoustic multimode waveguide system which consists of M parallel phononic crystal waveguides (M-PnCWs). Results show that the self-imaging principle remains applicable for acoustic waveguides just as it does for optical multimode waveguides. To achieve the dispersions and replicas of the input acoustic waves produced along the propagation direction, we performed the finite element method on M-PnCWs, which support M guided modes within the target frequency range. The simulation results show that single images (including direct and mirrored images) and N-fold images (N is an integer) are identified along the propagation direction with asymmetric and symmetric incidence discussed separately. The simulated positions of the replicas agree well with the calculated values that are theoretically decided by self-imaging conditions based on the guided mode propagation analysis. Moreover, the potential applications based on this self-imaging effect for acoustic wavelength de-multiplexing and beam splitting in the acoustic field are also presented.

  14. Negative refraction induced acoustic concentrator and the effects of scattering cancellation, imaging, and mirage

    NASA Astrophysics Data System (ADS)

    Wei, Qi; Cheng, Ying; Liu, Xiao-jun

    2012-07-01

    We present a three-dimensional acoustic concentrator capable of significantly enhancing the sound intensity in the compressive region with scattering cancellation, imaging, and mirage effects. The concentrator shell is built by isotropic gradient negative-index materials, which together with an exterior host medium slab constructs a pair of complementary media. The enhancement factor, which can approach infinity by tuning the geometric parameters, is always much higher than that of a traditional concentrator made by positive-index materials with the same size. The acoustic scattering theory is applied to derive the pressure field distribution of the concentrator, which is consistent with the numerical full-wave simulations. The inherent acoustic impedance match at the interfaces of the shell as well as the inverse processes of “negative refraction—progressive curvature—negative refraction” for arbitrary sound rays can exactly cancel the scattering of the concentrator. In addition, the concentrator shell can also function as an acoustic spherical magnifying superlens, which produces a perfect image with the same shape, with bigger geometric and acoustic parameters located at a shifted position. Then some acoustic mirages are observed whereby the waves radiated from (scattered by) an object located in the center region may seem to be radiated from (scattered by) its image. Based on the mirage effect, we further propose an intriguing acoustic transformer which can transform the sound scattering pattern of one object into another object at will with arbitrary geometric, acoustic, and location parameters.

  15. Tracking Energy Flow Using a Volumetric Acoustic Intensity Imager (VAIM)

    NASA Technical Reports Server (NTRS)

    Klos, Jacob; Williams, Earl G.; Valdivia, Nicolas P.

    2006-01-01

    A new measurement device has been invented at the Naval Research Laboratory which images instantaneously the intensity vector throughout a three-dimensional volume nearly a meter on a side. The measurement device consists of a nearly transparent spherical array of 50 inexpensive microphones optimally positioned on an imaginary spherical surface of radius 0.2m. Front-end signal processing uses coherence analysis to produce multiple, phase-coherent holograms in the frequency domain each related to references located on suspect sound sources in an aircraft cabin. The analysis uses either SVD or Cholesky decomposition methods using ensemble averages of the cross-spectral density with the fixed references. The holograms are mathematically processed using spherical NAH (nearfield acoustical holography) to convert the measured pressure field into a vector intensity field in the volume of maximum radius 0.4 m centered on the sphere origin. The utility of this probe is evaluated in a detailed analysis of a recent in-flight experiment in cooperation with Boeing and NASA on NASA s Aries 757 aircraft. In this experiment the trim panels and insulation were removed over a section of the aircraft and the bare panels and windows were instrumented with accelerometers to use as references for the VAIM. Results show excellent success at locating and identifying the sources of interior noise in-flight in the frequency range of 0 to 1400 Hz. This work was supported by NASA and the Office of Naval Research.

  16. Negative refraction imaging of acoustic metamaterial lens in the supersonic range

    NASA Astrophysics Data System (ADS)

    Han, Jianning; Wen, Tingdun; Yang, Peng; Zhang, Lu

    2014-05-01

    Acoustic metamaterials with negative refraction index is the most promising method to overcome the diffraction limit of acoustic imaging to achieve ultrahigh resolution. In this paper, we use localized resonant phononic crystal as the unit cell to construct the acoustic negative refraction lens. Based on the vibration model of the phononic crystal, negative quality parameters of the lens are obtained while excited near the system resonance frequency. Simulation results show that negative refraction of the acoustic lens can be achieved when a sound wave transmiting through the phononic crystal plate. The patterns of the imaging field agree well with that of the incident wave, while the dispersion is very weak. The unit cell size in the simulation is 0.0005 m and the wavelength of the sound source is 0.02 m, from which we show that acoustic signal can be manipulated through structures with dimensions much smaller than the wavelength of incident wave.

  17. Negative refraction imaging of acoustic metamaterial lens in the supersonic range

    SciTech Connect

    Han, Jianning; Wen, Tingdun; Yang, Peng; Zhang, Lu

    2014-05-15

    Acoustic metamaterials with negative refraction index is the most promising method to overcome the diffraction limit of acoustic imaging to achieve ultrahigh resolution. In this paper, we use localized resonant phononic crystal as the unit cell to construct the acoustic negative refraction lens. Based on the vibration model of the phononic crystal, negative quality parameters of the lens are obtained while excited near the system resonance frequency. Simulation results show that negative refraction of the acoustic lens can be achieved when a sound wave transmiting through the phononic crystal plate. The patterns of the imaging field agree well with that of the incident wave, while the dispersion is very weak. The unit cell size in the simulation is 0.0005 m and the wavelength of the sound source is 0.02 m, from which we show that acoustic signal can be manipulated through structures with dimensions much smaller than the wavelength of incident wave.

  18. Comparative sonographic appearance of nephroliths and associated acoustic shadowing artifacts in conventional vs. spatial compound imaging.

    PubMed

    Heng, Hock Gan; Rohleder, Jacob J; Pressler, Barrak M

    2012-01-01

    Spatial compound sonography improves visualization of tissue details and allows clearer delineation of structural margins. Improved image clarity is due to reduced speckling artifact; however, other types of acoustic shadowing artifacts may be unchanged or variably altered when conventional and spatial compound sonographic images are compared. Because intrarenal distal shadowing artifacts in conventional sonographic images are oftentimes the first or only evidence that a nephroliths is present, we compared the appearance and associated artifacts of nephroliths examined with both imaging modes. Consensus evaluation by two evaluators confirmed differences in appearance of nephroliths based on imaging mode. Nephroliths with conventional imaging mode were less hyperechoic and had better margin delineation while nephroliths were more hyperechoic and had less distinct margins with spatial compound imaging mode. Distal acoustic shadowing artifacts were present in 43% of spatial compound imaging mode vs. 86% of conventional imaging mode. When present in both imaging modes, intensity of these artifacts was weaker and the distance traveled was shorter in spatial compound imaging mode. Multiple diverging acoustic shadowing artifacts originating from a single source, the nephroliths were occasionally noted in spatial compound but not conventional imaging mode. These results demonstrate that the absence of distal acoustic shadowing cannot be used to exclude the presence of a nephrolith in dogs and cats. Optimal diagnosis of nephroliths, margin delineation, and visualization of the distal renal parenchyma requires paired radiography and sonography, and alternating between sonographic imaging modes is therefore suggested. PMID:22168895

  19. An Acoustic Charge Transport Imager for High Definition Television

    NASA Technical Reports Server (NTRS)

    Hunt, William D.; Brennan, Kevin; May, Gary; Glenn, William E.; Richardson, Mike; Solomon, Richard

    1999-01-01

    This project, over its term, included funding to a variety of companies and organizations. In addition to Georgia Tech these included Florida Atlantic University with Dr. William E. Glenn as the P.I., Kodak with Mr. Mike Richardson as the P.I. and M.I.T./Polaroid with Dr. Richard Solomon as the P.I. The focus of the work conducted by these organizations was the development of camera hardware for High Definition Television (HDTV). The focus of the research at Georgia Tech was the development of new semiconductor technology to achieve a next generation solid state imager chip that would operate at a high frame rate (I 70 frames per second), operate at low light levels (via the use of avalanche photodiodes as the detector element) and contain 2 million pixels. The actual cost required to create this new semiconductor technology was probably at least 5 or 6 times the investment made under this program and hence we fell short of achieving this rather grand goal. We did, however, produce a number of spin-off technologies as a result of our efforts. These include, among others, improved avalanche photodiode structures, significant advancement of the state of understanding of ZnO/GaAs structures and significant contributions to the analysis of general GaAs semiconductor devices and the design of Surface Acoustic Wave resonator filters for wireless communication. More of these will be described in the report. The work conducted at the partner sites resulted in the development of 4 prototype HDTV cameras. The HDTV camera developed by Kodak uses the Kodak KAI-2091M high- definition monochrome image sensor. This progressively-scanned charge-coupled device (CCD) can operate at video frame rates and has 9 gm square pixels. The photosensitive area has a 16:9 aspect ratio and is consistent with the "Common Image Format" (CIF). It features an active image area of 1928 horizontal by 1084 vertical pixels and has a 55% fill factor. The camera is designed to operate in continuous mode with an output data rate of 5MHz, which gives a maximum frame rate of 4 frames per second. The MIT/Polaroid group developed two cameras under this program. The cameras have effectively four times the current video spatial resolution and at 60 frames per second are double the normal video frame rate.

  20. Analysis of Particle Image Velocimetry (PIV) Data for Acoustic Velocity Measurements

    NASA Technical Reports Server (NTRS)

    Blackshire, James L.

    1997-01-01

    Acoustic velocity measurements were taken using Particle Image Velocimetry (PIV) in a Normal Incidence Tube configuration at various frequency, phase, and amplitude levels. This report presents the results of the PIV analysis and data reduction portions of the test and details the processing that was done. Estimates of lower measurement sensitivity levels were determined based on PIV image quality, correlation, and noise level parameters used in the test. Comparison of measurements with linear acoustic theory are presented. The onset of nonlinear, harmonic frequency acoustic levels were also studied for various decibel and frequency levels ranging from 90 to 132 dB and 500 to 3000 Hz, respectively.

  1. Acoustics

    NASA Technical Reports Server (NTRS)

    Goodman, Jerry R.; Grosveld, Ferdinand

    2007-01-01

    The acoustics environment in space operations is important to maintain at manageable levels so that the crewperson can remain safe, functional, effective, and reasonably comfortable. High acoustic levels can produce temporary or permanent hearing loss, or cause other physiological symptoms such as auditory pain, headaches, discomfort, strain in the vocal cords, or fatigue. Noise is defined as undesirable sound. Excessive noise may result in psychological effects such as irritability, inability to concentrate, decrease in productivity, annoyance, errors in judgment, and distraction. A noisy environment can also result in the inability to sleep, or sleep well. Elevated noise levels can affect the ability to communicate, understand what is being said, hear what is going on in the environment, degrade crew performance and operations, and create habitability concerns. Superfluous noise emissions can also create the inability to hear alarms or other important auditory cues such as an equipment malfunctioning. Recent space flight experience, evaluations of the requirements in crew habitable areas, and lessons learned (Goodman 2003; Allen and Goodman 2003; Pilkinton 2003; Grosveld et al. 2003) show the importance of maintaining an acceptable acoustics environment. This is best accomplished by having a high-quality set of limits/requirements early in the program, the "designing in" of acoustics in the development of hardware and systems, and by monitoring, testing and verifying the levels to ensure that they are acceptable.

  2. ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS

    SciTech Connect

    Thurman E. Scott, Jr.; Younane Abousleiman

    2004-04-01

    The research during this project has concentrated on developing a correlation between rock deformation mechanisms and their acoustic velocity signature. This has included investigating: (1) the acoustic signature of drained and undrained unconsolidated sands, (2) the acoustic emission signature of deforming high porosity rocks (in comparison to their low porosity high strength counterparts), (3) the effects of deformation on anisotropic elastic and poroelastic moduli, and (4) the acoustic tomographic imaging of damage development in rocks. Each of these four areas involve triaxial experimental testing of weak porous rocks or unconsolidated sand and involves measuring acoustic properties. The research is directed at determining the seismic velocity signature of damaged rocks so that 3-D or 4-D seismic imaging can be utilized to image rock damage. These four areas of study are described in the report: (1) Triaxial compression experiments have been conducted on unconsolidated Oil Creek sand at high confining pressures. (2) Initial experiments on measuring the acoustic emission activity from deforming high porosity Danian chalk were accomplished and these indicate that the AE activity was of a very low amplitude. (3) A series of triaxial compression experiments were conducted to investigate the effects of induced stress on the anisotropy developed in dynamic elastic and poroelastic parameters in rocks. (4) Tomographic acoustic imaging was utilized to image the internal damage in a deforming porous limestone sample. Results indicate that the deformation damage in rocks induced during laboratory experimentation can be imaged tomographically in the laboratory. By extension the results also indicate that 4-D seismic imaging of a reservoir may become a powerful tool for imaging reservoir deformation (including imaging compaction and subsidence) and for imaging zones where drilling operation may encounter hazardous shallow water flows.

  3. Temporal pattern of acoustic imaging noise asymmetrically modulates activation in the auditory cortex.

    PubMed

    Ranaweera, Ruwan D; Kwon, Minseok; Hu, Shuowen; Tamer, Gregory G; Luh, Wen-Ming; Talavage, Thomas M

    2016-01-01

    This study investigated the hemisphere-specific effects of the temporal pattern of imaging related acoustic noise on auditory cortex activation. Hemodynamic responses (HDRs) to five temporal patterns of imaging noise corresponding to noise generated by unique combinations of imaging volume and effective repetition time (TR), were obtained using a stroboscopic event-related paradigm with extra-long (≥27.5 s) TR to minimize inter-acquisition effects. In addition to confirmation that fMRI responses in auditory cortex do not behave in a linear manner, temporal patterns of imaging noise were found to modulate both the shape and spatial extent of hemodynamic responses, with classically non-auditory areas exhibiting responses to longer duration noise conditions. Hemispheric analysis revealed the right primary auditory cortex to be more sensitive than the left to the presence of imaging related acoustic noise. Right primary auditory cortex responses were significantly larger during all the conditions. This asymmetry of response to imaging related acoustic noise could lead to different baseline activation levels during acquisition schemes using short TR, inducing an observed asymmetry in the responses to an intended acoustic stimulus through limitations of dynamic range, rather than due to differences in neuronal processing of the stimulus. These results emphasize the importance of accounting for the temporal pattern of the acoustic noise when comparing findings across different fMRI studies, especially those involving acoustic stimulation. PMID:26519093

  4. Acoustic imaging by second harmonic of phase-conjugate wave in inhomogeneous medium

    NASA Astrophysics Data System (ADS)

    Pyl'nov, Yu.; Pernod, P.; Preobrazhensky, V.

    2001-01-01

    Application of the supercritical magnetoelastic wave phase conjugation to harmonic imaging in acoustic C-scan microscopy is demonstrated. Second-harmonic generation by phase-conjugate wave is used for improvement of resolution of an imaging system. Possibility to compensate phase aberrations introduced in harmonic image by inhomogeneity of propagation medium is shown experimentally and explained theoretically.

  5. Acoustic and optical borehole-wall imaging for fractured-rock aquifer studies

    USGS Publications Warehouse

    Williams, J.H.; Johnson, C.D.

    2004-01-01

    Imaging with acoustic and optical televiewers results in continuous and oriented 360?? views of the borehole wall from which the character, relation, and orientation of lithologic and structural planar features can be defined for studies of fractured-rock aquifers. Fractures are more clearly defined under a wider range of conditions on acoustic images than on optical images including dark-colored rocks, cloudy borehole water, and coated borehole walls. However, optical images allow for the direct viewing of the character of and relation between lithology, fractures, foliation, and bedding. The most powerful approach is the combined application of acoustic and optical imaging with integrated interpretation. Imaging of the borehole wall provides information useful for the collection and interpretation of flowmeter and other geophysical logs, core samples, and hydraulic and water-quality data from packer testing and monitoring. ?? 2003 Elsevier B.V. All rights reserved.

  6. Biosonar acoustic images for target localization and classification by bats

    NASA Astrophysics Data System (ADS)

    Simmons, James A.

    1997-07-01

    Echolocating bats use sonar to guide interception of insects, recognize objects by shape, and even track prey in clutter. Broadcasts of the big brown bat are 0.5 to 20 ms FM signals in the 20-100 kHz ultrasonic band. Insects consist of several reflecting glints, each equivalent in cross- section to a small sphere of 2 mm to 2 cm radius, while clutter is typically composed of numerous glints distributed over a large volume. The bats' signals extend in space for many target lengths, while ka values for each glint are 0.5 to 30 across the broadcast band. Bats perceive acoustic images having echo delay as their primary dimension, and space is perceived in terms of the distribution of target glints in range. Range disparities between the ears provide two 'looks' at each target from slightly different locations as well as information about azimuth. The bats auditory system encodes the FM sweeps of broadcasts and echoes as linear-period spectrograms with integration-times of 300-400 micrometers . Bats nevertheless perceive individual glints in targets for echo-delay separations well inside the integration-time window. Deconvolution is achieved by spectrogram correlation in the time domain and spectral shape transformation in the frequency-domain, with all output evidently being displayed in the time domina. Neural responses in the bat's auditory system seem limited in time precision to 20-50 micrometers at best and 300 microsecond(s) to 3 ms in a broader sample, and stimulus phase is thought to be lost for frequencies above 1-3 kHz. Yet bats perceive echo delay with an accuracy of 10-15 ns and have two-echo resolution of about 2 microsecond(s) . Moreover, bats perceive echo phase-shifts as the correctly corresponding shifts in echo delay. Successive images are subtracted to enhance perception of shape from multiple 'looks', and echo phase is an integral part of this critical process. Utterly novel time-scale magnification appears in the bat's neural responses to ultrasonic broadcasts and echoes, with time-stretch factors of roughly 10 to 100 that account for the bat's mysteriously high temporal acuity. Bats reconstruct time-domain features of FM broadcasts and echoes in a compact, distributed format that incorporates delay, phase, glint separation, and inter-ear delay differences along the same image dimension.

  7. The path to COVIS: A review of acoustic imaging of hydrothermal flow regimes

    NASA Astrophysics Data System (ADS)

    Bemis, Karen G.; Silver, Deborah; Xu, Guangyu; Light, Russ; Jackson, Darrell; Jones, Christopher; Ozer, Sedat; Liu, Li

    2015-11-01

    Acoustic imaging of hydrothermal flow regimes started with the incidental recognition of a plume on a routine sonar scan for obstacles in the path of the human-occupied submersible ALVIN. Developments in sonar engineering, acoustic data processing and scientific visualization have been combined to develop technology which can effectively capture the behavior of focused and diffuse hydrothermal discharge. This paper traces the development of these acoustic imaging techniques for hydrothermal flow regimes from their conception through to the development of the Cabled Observatory Vent Imaging Sonar (COVIS). COVIS has monitored such flow eight times a day for several years. Successful acoustic techniques for estimating plume entrainment, bending, vertical rise, volume flux, and heat flux are presented as is the state-of-the-art in diffuse flow detection.

  8. Statistical optoacoustic image reconstruction using a-priori knowledge on the location of acoustic distortions

    NASA Astrophysics Data System (ADS)

    Deán-Ben, X. Luís; Ntziachristos, Vasilis; Razansky, Daniel

    2011-04-01

    Strong reflection and scattering effects, arising at the boundaries of acoustically mismatched areas in living organisms, such as bones, lungs, and other air cavities, may introduce severe image artifacts into optoacoustic reconstructions. Yet, in many cases, an a priori knowledge on the location of strongly mismatched areas is available, either based on general anatomical knowledge or using other imaging modalities. In this letter, we suggest a statistical optoacoustic image reconstruction method, which uses a priori knowledge on the location of acoustic distortions in order to improve image quality and quantification. Significant improvements are showcased experimentally on tissue mimicking phantoms of different complexities.

  9. Acoustic micro-Doppler radar for human gait imaging.

    PubMed

    Zhang, Zhaonian; Pouliquen, Philippe O; Waxman, Allen; Andreou, Andreas G

    2007-03-01

    A portable acoustic micro-Doppler radar system for the acquisition of human gait signatures in indoor and outdoor environments is reported. Signals from an accelerometer attached to the leg support the identification of the components in the measured micro-Doppler signature. The acoustic micro-Doppler system described in this paper is simpler and offers advantages over the widely used electromagnetic wave micro-Doppler radars. PMID:17407918

  10. Imaging and analyzing the elasticity of vascular smooth muscle cells by atomic force acoustic microscope.

    PubMed

    Zhang, Bo; Cheng, Qian; Chen, Ming; Yao, Wengang; Qian, Menglu; Hu, Bing

    2012-08-01

    Vascular smooth muscle cells (VSMCs) play an important role in the good performance of the vasculature. To study the surface, intracellular structure and elasticity of VSMCs, atomic force acoustic microscope (AFAM) was used for imaging VSMCs from A7r5 rat aorta arteries. The topography images of VSMCs were obtained in contact mode and the acoustic images were obtained by AFAM in sample vibration mode. Then, the force curve measurement derived using Young's modulus of the interested areas was used for evaluating elasticity properties. The acoustic images were found in higher resolution with more information than the topography images. The force curves showed the difference in Young's modulus of the different parts of VSMC. These findings demonstrate that AFAM is useful for displaying the surface, structure and elasticity property of VSMCs clearly, with short scanning time, negligible harm or damage to cell and nanometer-level resolution. PMID:22698505

  11. Planar-structure microscope-lens for simultaneous acoustic and optical imaging.

    PubMed

    Yamada, K; Sugiyama, T; Shimizu, H

    1991-01-01

    A new type of combined acoustic and optical microscope lens with a planar structure is proposed. It can meet the demand for simultaneously obtaining both an acoustic image and its optical counterpart. The lens is composed by uniting a Fresnel-zone-type acoustic lens developed by the authors with a rod-type gradient-index optical lens (SELFOC). An acoustic beam is converged to a focal point in water by an acoustic planar lens that is composed of annular grooves formed on the end of the SELFOC rod. An optical beam, emitted by a He-Ne laser source and guided into the rod, converges due to the gradient of the refractive index and focuses on a spot in water. By designing the length of the rod properly, the focal spot of the optical beam is set to coincide with that of an acoustic beam. The design and fabrication of the lens are described, and results of some preliminary experiments for simultaneous observation of acoustic and optical images of the same portion of a specimen are shown. PMID:18267573

  12. Reconstructed imaging of acoustic cloak using time-lapse reversal method

    NASA Astrophysics Data System (ADS)

    Zhou, Chen; Cheng, Ying; Xu, Jian-yi; Li, Bo; Liu, Xiao-jun

    2014-08-01

    We proposed and investigated a solution to the inverse acoustic cloak problem, an anti-stealth technology to make cloaks visible, using the time-lapse reversal (TLR) method. The TLR method reconstructs the image of an unknown acoustic cloak by utilizing scattered acoustic waves. Compared to previous anti-stealth methods, the TLR method can determine not only the existence of a cloak but also its exact geometric information like definite shape, size, and position. Here, we present the process for TLR reconstruction based on time reversal invariance. This technology may have potential applications in detecting various types of cloaks with different geometric parameters.

  13. Opti-acoustic stereo imaging: on system calibration and 3-D target reconstruction.

    PubMed

    Negahdaripour, Shahriar; Sekkati, Hicham; Pirsiavash, Hamed

    2009-06-01

    Utilization of an acoustic camera for range measurements is a key advantage for 3-D shape recovery of underwater targets by opti-acoustic stereo imaging, where the associated epipolar geometry of optical and acoustic image correspondences can be described in terms of conic sections. In this paper, we propose methods for system calibration and 3-D scene reconstruction by maximum likelihood estimation from noisy image measurements. The recursive 3-D reconstruction method utilized as initial condition a closed-form solution that integrates the advantages of two other closed-form solutions, referred to as the range and azimuth solutions. Synthetic data tests are given to provide insight into the merits of the new target imaging and 3-D reconstruction paradigm, while experiments with real data confirm the findings based on computer simulations, and demonstrate the merits of this novel 3-D reconstruction paradigm. PMID:19380272

  14. Acoustic dipole radiation based conductivity image reconstruction for magnetoacoustic tomography with magnetic induction

    NASA Astrophysics Data System (ADS)

    Sun, Xiaodong; Zhang, Feng; Ma, Qingyu; Tu, Juan; Zhang, Dong

    2012-01-01

    Based on the acoustic dipole radiation theory, a tomograhic conductivity image reconstruction algorithm is developed for the magnetoacoustic tomography with magnetic induction (MAT-MI) in a cylindrical measurement configuration. It has been experimentally proved for a tissue-like phantom that not only the configuration but also the inner conductivity distribution can be reconstructed without any borderline stripe. Furthermore, the spatial resolution also can be improved without the limitation of acoustic vibration. The favorable results have provided solid verification for the feasibility of conductivity image reconstruction and suggested the potential applications of MAT-MI in the area of medical electrical impedance imaging.

  15. Liver reserve function assessment by acoustic radiation force impulse imaging

    PubMed Central

    Sun, Xiao-Lan; Liang, Li-Wei; Cao, Hui; Men, Qiong; Hou, Ke-Zhu; Chen, Zhen; Zhao, Ya-E

    2015-01-01

    AIM: To evaluate the utility of liver reserve function by acoustic radiation force impulse (ARFI) imaging in patients with liver tumors. METHODS: Seventy-six patients with liver tumors were enrolled in this study. Serum biochemical indexes, such as aminotransferase (ALT), aspartate aminotransferase (AST), serum albumin (ALB), total bilirubin (T-Bil), and other indicators were observed. Liver stiffness (LS) was measured by ARFI imaging, measurements were repeated 10 times, and the average value of the results was taken as the final LS value. Indocyanine green (ICG) retention was performed, and ICG-K and ICG-R15 were recorded. Child-Pugh (CP) scores were carried out based on patients preoperative biochemical tests and physical condition. Correlations among CP scores, ICG-R15, ICG-K and LS values were observed and analyzed using either the Pearson correlation coefficient or the Spearman rank correlation coefficient. Kruskal-Wallis test was used to compare LS values of CP scores, and the receiver-operator characteristic (ROC) curve was used to analyze liver reserve function assessment accuracy. RESULTS: LS in the ICG-R15 10%-20% group was significantly higher than in the ICG-R15 < 10% group; and the difference was statistically significant (2.19 0.27 vs 1.59 0.32, P < 0.01). LS in the ICG-R15 > 20% group was significantly higher than in the ICG-R15 < 10% group; and the difference was statistically significant (2.92 0.29 vs 1.59 0.32, P < 0.01). The LS value in patients with CP class A was lower than in patients with CP class B (1.57 0.34 vs 1.86 0.27, P < 0.05), while the LS value in patients with CP class B was lower than in patients with CP class C (1.86 0.27 vs 2.47 0.33, P < 0.01). LS was positively correlated with ICG-R15 (r = 0.617, P < 0.01) and CP score (r = 0.772, P < 0.01). Meanwhile, LS was negatively correlated with ICG-K (r = -0.673, P < 0.01). AST, ALT and T-Bil were positively correlated with LS, while ALB was negatively correlated with LS (P < 0.05). The ROC curve revealed that the when the LS value was 2.34 m/s, the Youden index was at its highest point, sensitivity was 69.2% and specificity was 92.1%. CONCLUSION: For patients with liver tumors, ARFI imaging is a useful tool for assessing liver reserve function. PMID:26327773

  16. Two dimensional photoacoustic imaging based on an acoustic lens and the peak-hold technology

    NASA Astrophysics Data System (ADS)

    Zhang, Hanchao; Tang, Zhilie; He, Yongheng; Guo, Lina

    2007-06-01

    A new method of photoacoustic (PA) imaging based on an acoustic lens and the peak-hold technology is presented in this article. A fast PA imaging system, which consists of an acoustic lens, a 64-element linear transducer array, and a peak detection-and-hold circuit, is developed to obtain the two dimensional (2D) PA images of the experimental samples. By utilizing an acoustic lens, the PA signals generated from the sample are directly imaged on the imaging plane and collected by the 64-element linear transducer array which changes the PA signals into the corresponding electronic signals. Then the electronic signals are converted into a one dimensional image using the peak detection-and-hold circuit. After vertical scanning with a step motor on the imaging plane, the 2D PA image of the sample is achieved successfully. The results show that the images reconstructed in this experiment agree well with the original samples. Compared to other methods, this PA imaging system can acquire the PA images more rapidly without any complex algorithms, and it may provide a more convenient method for future in vivo noninvasive imaging of tissues and clinic diagnosis.

  17. Image Quality, Tissue Heating, and Frame Rate Trade-offs in Acoustic Radiation Force Impulse Imaging

    PubMed Central

    Bouchard, Richard R.; Dahl, Jeremy J.; Hsu, stephen J.; Palmeri, Mark L.; Trahey, Gregg E.

    2013-01-01

    The real-time application of acoustic radiation force impulse (ARFI) imaging requires both short acquisition times for a single ARFI image and repeated acquisition of these frames. Due to the high energy of pulses required to generate appreciable radiation force, however, repeated acquisitions could result in substantial transducer face and tissue heating. We describe and evaluate several novel beam sequencing schemes which, along with parallel-receive acquisition, are designed to reduce acquisition time and heating. These techniques reduce the total number of radiation force impulses needed to generate an image and minimize the time between successive impulses. We present qualitative and quantitative analyses of the trade-offs in image quality resulting from the acquisition schemes. Results indicate that these techniques yield a significant improvement in frame rate with only moderate decreases in image quality. Tissue and transducer face heating resulting from these schemes is assessed through finite element method modeling and thermocouple measurements. Results indicate that heating issues can be mitigated by employing ARFI acquisition sequences that utilize the highest track-to-excitation ratio possible. PMID:19213633

  18. A surface acoustic wave /SAW/ charge transfer imager

    NASA Technical Reports Server (NTRS)

    Papanicolauo, N. A.; Lin, H. C.

    1981-01-01

    An 80 MHz, 2-microsecond surface acoustic wave charge transfer device (SAW-CTD) has been fabricated in which surface acoustic waves are used to create traveling longitudinal electric fields in the silicon substrate and to replace the multiphase clocks of charge coupled devices. The traveling electric fields create potential wells which will carry along charges that may be stored in the wells; the charges may be injected into the wells by light. An optical application is proposed where the SAW-CTD structure is used in place of a conventional interline transfer design.

  19. Small-aperture acoustic imaging using model-based array signal processing

    NASA Astrophysics Data System (ADS)

    Kraeutner, Paul Hans

    Acoustic imaging systems are often used underwater where light is either unavailable or severely attenuated. Acoustic images are typically constructed by transmitting a pulse of acoustic energy into the environment and then striving to resolve the three dimensional spatial origin of received echoes or backscatter. This thesis introduces a new concept for spatially localizing acoustic backscatter called Computed Angle-of-Arrival Transient Imaging (CAATI) that constructs an image by explicitly computing plane wave arrival angles and amplitudes as a function of range from the sonar (i.e. two way travel time after transmit). In contrast to lens or beamformer based imaging methods, the resolution of the new approach is not limited by the physical size of the receive transducer but instead by model uncertainties, and therefore high resolution may be obtained using a small aperture. Plane wave decomposition based on one degree-of-freedom (i.e. a single plane wave is assumed with a time varying amplitude and angle-of-arrival) has for some time been employed by interferometric sidescan sonars to perform 3D imaging of the seafloor using two closely spaced array elements. However, the inability of interferometry to separate multiple concurrent plane wave components has relegated these systems to use in predominantly flat, slowly varying seafloor geometries under conditions of no multipath. CAATI on the other hand extends the number of resolveable concurrent plane wave arrivals to N/2 under coherent signal conditions and N-1 for uncorrelated signal conditions using an N element linear array. The principles underlying the new approach are presented and the factors affecting the validity of the approach under both ideal and non-ideal signal conditions are analyzed and discussed. Alternative array signal processing methods for computing plane wave arrival angles are reviewed and considered in the context of acoustic backscatter imaging. Simulation results are presented in which acoustic backscatter is synthesized for an image phantom (corner reflector) chosen to demonstrate both the viability of the method under non- ideal signal conditions and its advantages over interferometric and beamformed imaging methods. A prototype design for a new seafloor imaging sonar concept called Small Aperture Range vs Angle sonar (SARA) is then described and results are presented for 3D imaging experiments conducted in both a test tank and a lake. The success of CAATI and SARA demonstrates the practical utility of small aperture acoustic imaging using model based array signal processing and opens the door to a new field of imaging research.

  20. Segmentation and classification of shallow subbottom acoustic data, using image processing and neural networks

    NASA Astrophysics Data System (ADS)

    Yegireddi, Satyanarayana; Thomas, Nitheesh

    2014-06-01

    Subbottom acoustic profiler provides acoustic imaging of the subbottom structure constituting the upper sediment layers of the seabed, which is essential for geological and offshore geo-engineering studies. Delineation of the subbottom structure from a noisy acoustic data and classification of the sediment strata is a challenging task with the conventional signal processing techniques. Image processing techniques utilise the spatial variability of the image characteristics, known for their potential in medical imaging and pattern recognition applications. In the present study, they are found to be good in demarcating the boundaries of the sediment layers associated with weak acoustic reflectivity, masked by noisy background. The study deals with application of image processing techniques, like segmentation in identification of subbottom features and extraction of textural feature vectors using grey level co-occurrence matrix statistics. And also attempted classification using Self Organised Map, an unsupervised neural network model utilising these feature vectors. The methodology was successfully demonstrated in demarcating the different sediment layers from the subbottom images and established the sediments constituting the inferred four subsurface sediment layers differ from each other. The network model was also tested for its consistency, with repeated runs of different configuration of the network. Also the ability of simulated network was tested using a few untrained test images representing the similar environment and the classification results show a good agreement with the anticipated.

  1. An acoustic charge transport imager for high definition television applications

    NASA Technical Reports Server (NTRS)

    Hunt, William D.; Brennan, Kevin F.; Summers, Chris J.

    1992-01-01

    In this report we present the progress during the second six month period of the project. This includes both experimental and theoretical work on the acoustic charge transport (ACT) portion of the chip, the theoretical program modelling of both the avalanche photodiode (APD) and the charge transfer and overflow transistor and the materials growth and fabrication part of the program.

  2. Method and apparatus for detecting internal structures of bulk objects using acoustic imaging

    DOEpatents

    Deason, Vance A. (Idaho Falls, ID); Telschow, Kenneth L. (Idaho Falls, ID)

    2002-01-01

    Apparatus for producing an acoustic image of an object according to the present invention may comprise an excitation source for vibrating the object to produce at least one acoustic wave therein. The acoustic wave results in the formation of at least one surface displacement on the surface of the object. A light source produces an optical object wavefront and an optical reference wavefront and directs the optical object wavefront toward the surface of the object to produce a modulated optical object wavefront. A modulator operatively associated with the optical reference wavefront modulates the optical reference wavefront in synchronization with the acoustic wave to produce a modulated optical reference wavefront. A sensing medium positioned to receive the modulated optical object wavefront and the modulated optical reference wavefront combines the modulated optical object and reference wavefronts to produce an image related to the surface displacement on the surface of the object. A detector detects the image related to the surface displacement produced by the sensing medium. A processing system operatively associated with the detector constructs an acoustic image of interior features of the object based on the phase and amplitude of the surface displacement on the surface of the object.

  3. Acoustic imaging of vapor bubbles through optically non-transparent media

    SciTech Connect

    Kolbe, W.F.; Turko, B.T.; Leskovar, B.

    1983-10-01

    A preliminary investigation of the feasibility of acoustic imaging of vapor bubbles through optically nontransparent media is described. Measurements are reported showing the echo signals produced by air filled glass spheres of various sizes positioned in an aqueous medium as well as signals produced by actual vapor bubbles within a water filled steel pipe. In addition, the influence of the metallic wall thickness and material on the amplitude of the echo signals is investigated. Finally several examples are given of the imaging of spherical bubbles within metallic pipes using a simulated array of acoustic transducers mounted circumferentially around the pipe. The measurement procedures and a description of the measuring system are also given.

  4. Exploration of amphoteric and negative refraction imaging of acoustic sources via active metamaterials

    NASA Astrophysics Data System (ADS)

    Wen, Jihong; Shen, Huijie; Yu, Dianlong; Wen, Xisen

    2013-11-01

    The present work describes the design of three flat superlens structures for acoustic source imaging and explores an active acoustic metamaterial (AAM) to realise such a design. The first two lenses are constructed via the coordinate transform method (CTM), and their constituent materials are anisotropic. The third lens consists of a material that has both a negative density and a negative bulk modulus. In these lenses, the quality of the images is “clear” and sharp; thus, the diffraction limit of classical lenses is overcome. Finally, a multi-control strategy is developed to achieve the desired parameters and to eliminate coupling effects in the AAM.

  5. 77 FR 321 - Section 4(f) Policy Paper

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-04

    ... Federal Highway Administration Section 4(f) Policy Paper AGENCY: Federal Highway Administration (FHWA... draft Section 4(f) Policy Paper that will provide guidance on the procedures the FHWA will follow when... practicable. Background A copy of the proposed Section 4(f) Policy Paper is available for download and...

  6. 23 CFR 774.3 - Section 4(f) approvals.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ..., RECREATION AREAS, WILDLIFE AND WATERFOWL REFUGES, AND HISTORIC SITES (SECTION 4(F)) § 774.3 Section 4(f... With Public Parks, Recreation Lands, Wildlife and Waterfowl Refuges, and Historic Sites; (3) Final... With Historic Sites; (4) Historic Bridges; Programmatic Section 4(f) Evaluation and Approval; and...

  7. Method and system to synchronize acoustic therapy with ultrasound imaging

    NASA Technical Reports Server (NTRS)

    Owen, Neil (Inventor); Bailey, Michael R. (Inventor); Hossack, James (Inventor)

    2009-01-01

    Interference in ultrasound imaging when used in connection with high intensity focused ultrasound (HIFU) is avoided by employing a synchronization signal to control the HIFU signal. Unless the timing of the HIFU transducer is controlled, its output will substantially overwhelm the signal produced by ultrasound imaging system and obscure the image it produces. The synchronization signal employed to control the HIFU transducer is obtained without requiring modification of the ultrasound imaging system. Signals corresponding to scattered ultrasound imaging waves are collected using either the HIFU transducer or a dedicated receiver. A synchronization processor manipulates the scattered ultrasound imaging signals to achieve the synchronization signal, which is then used to control the HIFU bursts so as to substantially reduce or eliminate HIFU interference in the ultrasound image. The synchronization processor can alternatively be implemented using a computing device or an application-specific circuit.

  8. Electromagnetic-Acoustic Modeling of Fields Induced by Gradient Pulses in Diffusion Tensor Magnetic Resonance Imaging

    NASA Astrophysics Data System (ADS)

    Elshafiey, I.; Melapudi, V. R.; Udpa, L.

    2006-03-01

    Diffusion tensor magnetic resonance imaging (DT-MRI) has recently gained popularity because of its capabilities in axonography of the central nervous system. Fast imaging sequences are used to reduce motion induced distortion effects on the diffusion signal, resulting in low signal levels, loud acoustic noise, and occasional peripheral nerve stimulation. Eddy current induced by diffusion gradient pulses is also a challenge to DT-MRI. Magnetic field associated with the eddy current is a major source of artifacts in scanner images. This paper introduces a finite element modeling of electromagnetic and acoustic fields in DT-MRI sequences. The analysis involves three dimensional modeling of the scanner and its interaction with pulses applied to gradient coils. Efficient modeling of induced fields is essential in optimizing parameter settings and improving performance of this imaging modality.

  9. Imaging of acoustic pressure radiation from vibrating microstructure in atmosphere using thermal microprobe

    NASA Astrophysics Data System (ADS)

    Ono, Takahito; Kim, Sang-Jin; Esashi, Masayoshi

    2007-05-01

    This letter reports on an imaging technique of acoustic pressure radiation (APR) from vibrating micro-/nanostructures and their mechanical defects. Resonance oscillation of micro-/nanometer beams in use of viscous environments is important for various sensing applications. Viscous dumping is the main energy loss mechanism, which determines the quality factor of resonance in viscous fluid. The APR due to viscous dumping is imaged using a scanning thermal flow sensor. A platinum heater or micromachined silicon heater is heated up by flowing a current, and the acoustic particle velocity which originated from APR is detected. Imaging of APR is demonstrated and compared with the actual vibration image. Also, strong APR is observed from a crack on the support of a silicon beam.

  10. Development of an Acoustic Lens for an Imaging Sonar for Autonomous Underwater Vehicle Urashima and Experimentation in a Water Tank

    NASA Astrophysics Data System (ADS)

    Tsukioka, Satoshi; Aoki, Taro; Ochi, Hiroshi; Shimura, Takuya; Sawa, Takao; Nakamura, Toshiaki; Anada, Tetsuo; Kaihou, Ieharu; Noda, Hiroaki

    2002-06-01

    Underwater imaging sonar has been developed for obstacle avoidance and navigation of the autonomous underwater vehicle (AUV) URASHIMA. The acoustic image, the distance and the azimuth of the target are obtained using an acoustic lens. Tone burst acoustic waves are transmitted and scattered at the target, and a direct image of the target can be created on a two-dimensional receiving array. The merits of the acoustic lens system are the possibility to omit the extensive calculation required for signal processing of received signals at each element to form two-dimensional beams, and reduction of equipment size. In this report, the outline of the imaging sonar with a single spherical lens and the experimental results for the acoustic lens in a water tank are presented. Then, theoretical calculation of the sound field through the lens using the parabolic equation method is introduced as a useful tool for improvement of lens performance to solve problems in resolution and aberration.

  11. Time-resolved coherent X-ray diffraction imaging of surface acoustic waves

    PubMed Central

    Nicolas, Jan-David; Reusch, Tobias; Osterhoff, Markus; Sprung, Michael; Schlein, Florian J. R.; Krenner, Hubert J.; Wixforth, Achim; Salditt, Tim

    2014-01-01

    Time-resolved coherent X-ray diffraction experiments of standing surface acoustic waves, illuminated under grazing incidence by a nanofocused synchrotron beam, are reported. The data have been recorded in stroboscopic mode at controlled and varied phase between the acoustic frequency generator and the synchrotron bunch train. At each time delay (phase angle), the coherent far-field diffraction pattern in the small-angle regime is inverted by an iterative algorithm to yield the local instantaneous surface height profile along the optical axis. The results show that periodic nanoscale dynamics can be imaged at high temporal resolution in the range of 50?ps (pulse length). PMID:25294979

  12. Modern Techniques in Acoustical Signal and Image Processing

    SciTech Connect

    Candy, J V

    2002-04-04

    Acoustical signal processing problems can lead to some complex and intricate techniques to extract the desired information from noisy, sometimes inadequate, measurements. The challenge is to formulate a meaningful strategy that is aimed at performing the processing required even in the face of uncertainties. This strategy can be as simple as a transformation of the measured data to another domain for analysis or as complex as embedding a full-scale propagation model into the processor. The aims of both approaches are the same--to extract the desired information and reject the extraneous, that is, develop a signal processing scheme to achieve this goal. In this paper, we briefly discuss this underlying philosophy from a ''bottom-up'' approach enabling the problem to dictate the solution rather than visa-versa.

  13. An acoustic charge transport imager for high definition television applications

    NASA Astrophysics Data System (ADS)

    Hunt, William D.; Brennan, Kevin F.; Summers, Christopher J.

    1993-09-01

    This report covers: (1) invention of a new, ultra-low noise, low operating voltage APD which is expected to offer far better performance than the existing volume doped APD device; (2) performance of a comprehensive series of experiments on the acoustic and piezoelectric properties of ZnO films sputtered on GaAs which can possibly lead to a decrease in the required rf drive power for ACT devices by 15dB; (3) development of an advanced, hydrodynamic, macroscopic simulator used for evaluating the performance of ACT and CTD devices and aiding in the development of the next generation of devices; (4) experimental development of CTD devices which utilize a p-doped top barrier demonstrating charge storage capacity and low leakage currents; (5) refinements in materials growth techniques and in situ controls to lower surface defect densities to record levels as well as increase material uniformity and quality.

  14. An acoustic charge transport imager for high definition television applications

    NASA Technical Reports Server (NTRS)

    Hunt, William D.; Brennan, Kevin F.; Summers, Christopher J.

    1993-01-01

    This report covers: (1) invention of a new, ultra-low noise, low operating voltage APD which is expected to offer far better performance than the existing volume doped APD device; (2) performance of a comprehensive series of experiments on the acoustic and piezoelectric properties of ZnO films sputtered on GaAs which can possibly lead to a decrease in the required rf drive power for ACT devices by 15dB; (3) development of an advanced, hydrodynamic, macroscopic simulator used for evaluating the performance of ACT and CTD devices and aiding in the development of the next generation of devices; (4) experimental development of CTD devices which utilize a p-doped top barrier demonstrating charge storage capacity and low leakage currents; (5) refinements in materials growth techniques and in situ controls to lower surface defect densities to record levels as well as increase material uniformity and quality.

  15. Investigation of an acoustical holography system for real-time imaging

    NASA Astrophysics Data System (ADS)

    Fecht, Barbara A.; Andre, Michael P.; Garlick, George F.; Shelby, Ronald L.; Shelby, Jerod O.; Lehman, Constance D.

    1998-07-01

    A new prototype imaging system based on ultrasound transmission through the object of interest -- acoustical holography -- was developed which incorporates significant improvements in acoustical and optical design. This system is being evaluated for potential clinical application in the musculoskeletal system, interventional radiology, pediatrics, monitoring of tumor ablation, vascular imaging and breast imaging. System limiting resolution was estimated using a line-pair target with decreasing line thickness and equal separation. For a swept frequency beam from 2.6 - 3.0 MHz, the minimum resolution was 0.5 lp/mm. Apatite crystals were suspended in castor oil to approximate breast microcalcifications. Crystals from 0.425 - 1.18 mm in diameter were well resolved in the acoustic zoom mode. Needle visibility was examined with both a 14-gauge biopsy needle and a 0.6 mm needle. The needle tip was clearly visible throughout the dynamic imaging sequence as it was slowly inserted into a RMI tissue-equivalent breast biopsy phantom. A selection of human images was acquired in several volunteers: a 25 year-old female volunteer with normal breast tissue, a lateral view of the elbow joint showing muscle fascia and tendon insertions, and the superficial vessels in the forearm. Real-time video images of these studies will be presented. In all of these studies, conventional sonography was used for comparison. These preliminary investigations with the new prototype acoustical holography system showed favorable results in comparison to state-of-the-art pulse-echo ultrasound and demonstrate it to be suitable for further clinical study. The new patient interfaces will facilitate orthopedic soft tissue evaluation, study of superficial vascular structures and potentially breast imaging.

  16. Phase Time and Envelope Time in Time-Distance Analysis and Acoustic Imaging

    NASA Technical Reports Server (NTRS)

    Chou, Dean-Yi; Duvall, Thomas L.; Sun, Ming-Tsung; Chang, Hsiang-Kuang; Jimenez, Antonio; Rabello-Soares, Maria Cristina; Ai, Guoxiang; Wang, Gwo-Ping; Goode Philip; Marquette, William; Ehgamberdiev, Shuhrat; Landenkov, Oleg

    1999-01-01

    Time-distance analysis and acoustic imaging are two related techniques to probe the local properties of solar interior. In this study, we discuss the relation of phase time and envelope time between the two techniques. The location of the envelope peak of the cross correlation function in time-distance analysis is identified as the travel time of the wave packet formed by modes with the same w/l. The phase time of the cross correlation function provides information of the phase change accumulated along the wave path, including the phase change at the boundaries of the mode cavity. The acoustic signals constructed with the technique of acoustic imaging contain both phase and intensity information. The phase of constructed signals can be studied by computing the cross correlation function between time series constructed with ingoing and outgoing waves. In this study, we use the data taken with the Taiwan Oscillation Network (TON) instrument and the Michelson Doppler Imager (MDI) instrument. The analysis is carried out for the quiet Sun. We use the relation of envelope time versus distance measured in time-distance analyses to construct the acoustic signals in acoustic imaging analyses. The phase time of the cross correlation function of constructed ingoing and outgoing time series is twice the difference between the phase time and envelope time in time-distance analyses as predicted. The envelope peak of the cross correlation function between constructed ingoing and outgoing time series is located at zero time as predicted for results of one-bounce at 3 mHz for all four data sets and two-bounce at 3 mHz for two TON data sets. But it is different from zero for other cases. The cause of the deviation of the envelope peak from zero is not known.

  17. X-ray imaging of surface acoustic waves generated in semiconductor crystals by an external transducer

    NASA Astrophysics Data System (ADS)

    Shilo, D.; Lakin, E.; Zolotoyabko, E.; Härtwig, J.; Baruchel, J.

    2003-03-01

    We demonstrate successful x-ray-diffraction imaging of high-frequency (0.29-GHz) surface acoustic waves (SAWs) propagating in semiconductor crystals (Si and GaAs) with no deposited electrodes on top of them. Experiments were performed at the ID19 beamline of the European Synchrotron Radiation Facility (Grenoble). We used the stroboscopic x-ray topography technique, in which x-ray bursts coming from the storage ring are synchronized with the excited acoustic waves. This technique is able to visualize individual acoustic wave fronts of traveling SAWs and their distortions caused by phonon scattering. In order to generate SAW in semiconductor crystals the latter were coupled to LiNbO3-based SAW transducers via contact liquids. The maximum SAW transmission is achieved for evanescent waves under optimized coupling conditions at the liquid/sample interface. The technique developed opens a way to directly study phonon interaction with defects in nonpiezoelectric and weakly piezoelectric crystals.

  18. Acoustic imaging with time reversal methods: From medicine to NDT

    NASA Astrophysics Data System (ADS)

    Fink, Mathias

    2015-03-01

    This talk will present an overview of the research conducted on ultrasonic time-reversal methods applied to biomedical imaging and to non-destructive testing. We will first describe iterative time-reversal techniques that allow both focusing ultrasonic waves on reflectors in tissues (kidney stones, micro-calcifications, contrast agents) or on flaws in solid materials. We will also show that time-reversal focusing does not need the presence of bright reflectors but it can be achieved only from the speckle noise generated by random distributions of non-resolved scatterers. We will describe the applications of this concept to correct distortions and aberrations in ultrasonic imaging and in NDT. In the second part of the talk we will describe the concept of time-reversal processors to get ultrafast ultrasonic images with typical frame rates of order of 10.000 F/s. It is the field of ultrafast ultrasonic imaging that has plenty medical applications and can be of great interest in NDT. We will describe some applications in the biomedical domain: Quantitative Elasticity imaging of tissues by following shear wave propagation to improve cancer detection and Ultrafast Doppler imaging that allows ultrasonic functional imaging.

  19. Imaging of transient surface acoustic waves by full-field photorefractive interferometry.

    PubMed

    Xiong, Jichuan; Xu, Xiaodong; Glorieux, Christ; Matsuda, Osamu; Cheng, Liping

    2015-05-01

    A stroboscopic full-field imaging technique based on photorefractive interferometry for the visualization of rapidly changing surface displacement fields by using of a standard charge-coupled device (CCD) camera is presented. The photorefractive buildup of the space charge field during and after probe laser pulses is simulated numerically. The resulting anisotropic diffraction upon the refractive index grating and the interference between the polarization-rotated diffracted reference beam and the transmitted signal beam are modeled theoretically. The method is experimentally demonstrated by full-field imaging of the propagation of photoacoustically generated surface acoustic waves with a temporal resolution of nanoseconds. The surface acoustic wave propagation in a 23 mm 17 mm area on an aluminum plate was visualized with 520 696 pixels of the CCD sensor, yielding a spatial resolution of 33 ?m. The short pulse duration (8 ns) of the probe laser yields the capability of imaging SAWs with frequencies up to 60 MHz. PMID:26026514

  20. Imaging of transient surface acoustic waves by full-field photorefractive interferometry

    NASA Astrophysics Data System (ADS)

    Xiong, Jichuan; Xu, Xiaodong; Glorieux, Christ; Matsuda, Osamu; Cheng, Liping

    2015-05-01

    A stroboscopic full-field imaging technique based on photorefractive interferometry for the visualization of rapidly changing surface displacement fields by using of a standard charge-coupled device (CCD) camera is presented. The photorefractive buildup of the space charge field during and after probe laser pulses is simulated numerically. The resulting anisotropic diffraction upon the refractive index grating and the interference between the polarization-rotated diffracted reference beam and the transmitted signal beam are modeled theoretically. The method is experimentally demonstrated by full-field imaging of the propagation of photoacoustically generated surface acoustic waves with a temporal resolution of nanoseconds. The surface acoustic wave propagation in a 23 mm × 17 mm area on an aluminum plate was visualized with 520 × 696 pixels of the CCD sensor, yielding a spatial resolution of 33 μm. The short pulse duration (8 ns) of the probe laser yields the capability of imaging SAWs with frequencies up to 60 MHz.

  1. Imaging of transient surface acoustic waves by full-field photorefractive interferometry

    SciTech Connect

    Xiong, Jichuan; Xu, Xiaodong E-mail: christ.glorieux@fys.kuleuven.be; Glorieux, Christ E-mail: christ.glorieux@fys.kuleuven.be; Matsuda, Osamu; Cheng, Liping

    2015-05-15

    A stroboscopic full-field imaging technique based on photorefractive interferometry for the visualization of rapidly changing surface displacement fields by using of a standard charge-coupled device (CCD) camera is presented. The photorefractive buildup of the space charge field during and after probe laser pulses is simulated numerically. The resulting anisotropic diffraction upon the refractive index grating and the interference between the polarization-rotated diffracted reference beam and the transmitted signal beam are modeled theoretically. The method is experimentally demonstrated by full-field imaging of the propagation of photoacoustically generated surface acoustic waves with a temporal resolution of nanoseconds. The surface acoustic wave propagation in a 23 mm × 17 mm area on an aluminum plate was visualized with 520 × 696 pixels of the CCD sensor, yielding a spatial resolution of 33 μm. The short pulse duration (8 ns) of the probe laser yields the capability of imaging SAWs with frequencies up to 60 MHz.

  2. Methods And Systems For Using Reference Images In Acoustic Image Processing

    DOEpatents

    Moore, Thomas L.; Barter, Robert Henry

    2005-01-04

    A method and system of examining tissue are provided in which a field, including at least a portion of the tissue and one or more registration fiducials, is insonified. Scattered acoustic information, including both transmitted and reflected waves, is received from the field. A representation of the field, including both the tissue and the registration fiducials, is then derived from the received acoustic radiation.

  3. Three dimensional full-wave nonlinear acoustic simulations: Applications to ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Pinton, Gianmarco

    2015-10-01

    Characterization of acoustic waves that propagate nonlinearly in an inhomogeneous medium has significant applications to diagnostic and therapeutic ultrasound. The generation of an ultrasound image of human tissue is based on the complex physics of acoustic wave propagation: diffraction, reflection, scattering, frequency dependent attenuation, and nonlinearity. The nonlinearity of wave propagation is used to the advantage of diagnostic scanners that use the harmonic components of the ultrasonic signal to improve the resolution and penetration of clinical scanners. One approach to simulating ultrasound images is to make approximations that can reduce the physics to systems that have a low computational cost. Here a maximalist approach is taken and the full three dimensional wave physics is simulated with finite differences. This paper demonstrates how finite difference simulations for the nonlinear acoustic wave equation can be used to generate physically realistic two and three dimensional ultrasound images anywhere in the body. A specific intercostal liver imaging scenario for two cases: with the ribs in place, and with the ribs removed. This configuration provides an imaging scenario that cannot be performed in vivo but that can test the influence of the ribs on image quality. Several imaging properties are studied, in particular the beamplots, the spatial coherence at the transducer surface, the distributed phase aberration, and the lesion detectability for imaging at the fundamental and harmonic frequencies. The results indicate, counterintuitively, that at the fundamental frequency the beamplot improves due to the apodization effect of the ribs but at the same time there is more degradation from reverberation clutter. At the harmonic frequency there is significantly less improvement in the beamplot and also significantly less degradation from reverberation. It is shown that even though simulating the full propagation physics is computationally challenging it is necessary to quantify ultrasound image quality and its sources of degradation.

  4. Focused acoustic beam imaging of grain structure and local Young's modulus with Rayleigh and surface skimming longitudinal waves

    NASA Astrophysics Data System (ADS)

    Martin, R. W.; Sathish, S.; Blodgett, M. P.

    2013-01-01

    The interaction of a focused acoustic beam with materials generates Rayleigh surface waves (RSW) and surface skimming longitudinal waves (SSLW). Acoustic microscopic investigations have used the RSW amplitude and the velocity measurements, extensively for grain structure analysis. Although, the presence of SSLW has been recognized, it is rarely used in acoustic imaging. This paper presents an approach to perform microstructure imaging and local elastic modulus measurements by combining both RSW and SSLW. The acoustic imaging of grain structure was performed by measuring the amplitude of RSW and SSLW signal. The microstructure images obtained on the same region of the samples with RSW and SSLW are compared and the difference in the contrast observed is discussed based on the propagation characteristics of the individual surface waves. The velocity measurements are determined by two point defocus method. The surface wave velocities of RSW and SSLW of the same regions of the sample are combined and presented as average Young's modulus image.

  5. Focused acoustic beam imaging of grain structure and local Young's modulus with Rayleigh and surface skimming longitudinal waves

    SciTech Connect

    Martin, R. W.; Sathish, S.; Blodgett, M. P.

    2013-01-25

    The interaction of a focused acoustic beam with materials generates Rayleigh surface waves (RSW) and surface skimming longitudinal waves (SSLW). Acoustic microscopic investigations have used the RSW amplitude and the velocity measurements, extensively for grain structure analysis. Although, the presence of SSLW has been recognized, it is rarely used in acoustic imaging. This paper presents an approach to perform microstructure imaging and local elastic modulus measurements by combining both RSW and SSLW. The acoustic imaging of grain structure was performed by measuring the amplitude of RSW and SSLW signal. The microstructure images obtained on the same region of the samples with RSW and SSLW are compared and the difference in the contrast observed is discussed based on the propagation characteristics of the individual surface waves. The velocity measurements are determined by two point defocus method. The surface wave velocities of RSW and SSLW of the same regions of the sample are combined and presented as average Young's modulus image.

  6. Fast photoacoustic imaging with a line scanning optical-acoustical resolution photoacoustic microscope (LS-OAR-PAM)

    NASA Astrophysics Data System (ADS)

    Nuster, Robert; Paltauf, Guenther

    2015-07-01

    We present the concept, the setup and a preliminary experiment using optical ultrasound detection with a CCD camera combined with focused line excitation for photoacoustic microscopy. The line scanning optical-acoustical resolution photoacoustic microscope (LS-OAR-PAM) with optical ultrasound detection is capable of real-time B-scan imaging providing acoustical resolution within the individual B-scans and optical out of plane resolution up to a depth limited by optical diffusion. A 3D image is composed of reconstructed B-scan images recorded while scanning the excitation line along the sample surface. Proof of concept is shown by imaging a phantom containing black human hairs and carbon fibers. The obtained C-scan image clearly shows the different resolution in the two perpendicular directions, namely diffraction limited by optical focusing in scan direction and acoustically limited in direction parallel to line orientation by the properties of acoustic wave propagation.

  7. Quantitative high-resolution acoustic imaging of the seafloor

    NASA Astrophysics Data System (ADS)

    Holland, C. W.; Dettmer, J.; Steininger, G.; Dosso, S. E.

    2013-12-01

    Quantifying the properties of the seafloor interface and near surface (a few tens of meters) is of considerable interest to science as well as industry. Scales of interest range from the order of tens of kilometers (survey size) down to less than a centimeter. These scales can be probed using an AUV equipped with a broadband source and a short streamer. The data are processed for energy (rather than peak) reflection coefficients and scattering cross-section versus bi-static angle. In order to tackle spatial scales ranging over 8 orders of magnitude of, it is useful to divide the parameter space into deterministic and stochastic parameters. The energy reflection coefficients contain information on deterministic properties including sound speed, density and attenuation vs depth in the upper tens of meters of sediment. Vertical resolution is a function of depth, but typically of order 0.1 m near surface. The statistical properties of the smaller scales, i.e., seafloor roughness and/or volume heterogeneities are obtained from the bi-static scattering data. Physics-based models are used to relate the sediment micro-structure (the Buckingham model) and sediment fluctuations (the Von Karman spectrum) to the acoustic observables. Quantitative parameter and inter-parameter uncertainties are obtained from Bayesian methods for both deterministic and stochastic parameters.

  8. Design for Aplanatic Fresnel Acoustic Lens for Underwater Imaging

    NASA Astrophysics Data System (ADS)

    Sato, Yuji; Mizutani, Koichi; Wakatsuki, Naoto; Nakamura, Toshiaki

    2009-07-01

    We designed several shapes of aplanatic Fresnel acoustic lenses to correct spherical and coma aberrations. These lenses were made of room temperature vulcanizable (RTV) silicone rubber, and were designed by combining several aplanatic lenses. The converged sound pressure fields of these lenses were calculated numerically with the two-dimensional finite difference time domain (2D FDTD) method. The focal sound pressures of these lenses were 8-9 dB larger than those of aplanatic biconvex lenses. Comparing several aplanatic Fresnel lenses, the best convergence was achieved by the lens having the smoothest first surface. We assumed the reason for this advantage was the smooth first surface itself. Thus to smooth the first surface and to enlarge the focal sound pressure, small steps on the first surface were removed by two methods. The first method approximates the first surface to a polynomial equation. The second method changes the curvature of the aplanatic lenses to minimize the small steps; this method is called bending. The evaluation of the lenses made by the two methods showed that the resolutions of these lenses were higher than 1. The lens made by bending showed higher sound pressure than the lens made by the approximated surface.

  9. Analysis and verification of dominant factor to obtain the high resolution photo-acoustic imaging

    NASA Astrophysics Data System (ADS)

    Hirasawa, T.; Ishihara, M.; Kitagaki, M.; Bansaku, I.; Fujita, M.; Kikuchi, M.

    2011-03-01

    Our goal is to develop a photo-acoustic imaging (PAI) system which offers functional image of living tissues and organs with high resolution. In order to obtain high resolution image, we implemented the Fourier transform reconstruction algorithm which determines an optical absorption distribution from photo-acoustic (PA) signals. However, resolutions of reconstructed images were restricted by the sensor directionality, finite scan width and frequency band width. There was an essential requirement to optimize the sensor specification. In this study, we demonstrated relationship between image resolution and sensor specification by simulation and experiment. In our experimental system, PA signals were acquired by line scanning of our fabricated P(VDF/TrFE) film sensor. As results of simulations and experiments, lateral resolutions of PA images were restricted by the directionality of sensor. Furthermore, by limiting scan width and frequency band width, lateral resolution is decreased at deep region. The optimum sensor specification depends on the imaging region due to some trade-offs, for example, a sensor with wider directionality has less sensitivity, wider scan in same step increases acquisition time. Therefore, the results could indicate the possibility of optimizing sensor directionality, scan width and frequency band width for various depths and volumes of imaging region.

  10. Synthetic aperture acoustic imaging of canonical targets with a 2-15 kHz linear FM chirp

    NASA Astrophysics Data System (ADS)

    Vignola, Joseph F.; Judge, John A.; Good, Chelsea E.; Bishop, Steven S.; Gugino, Peter M.; Soumekh, Mehrdad

    2011-06-01

    Synthetic aperture image reconstruction applied to outdoor acoustic recordings is presented. Acoustic imaging is an alternate method having several military relevant advantages such as being immune to RF jamming, superior spatial resolution, capable of standoff side and forward-looking scanning, and relatively low cost, weight and size when compared to 0.5 - 3 GHz ground penetrating radar technologies. Synthetic aperture acoustic imaging is similar to synthetic aperture radar, but more akin to synthetic aperture sonar technologies owing to the nature of longitudinal or compressive wave propagation in the surrounding acoustic medium. The system's transceiver is a quasi mono-static microphone and audio speaker pair mounted on a rail 5meters in length. Received data sampling rate is 80 kHz with a 2- 15 kHz Linear Frequency Modulated (LFM) chirp, with a pulse repetition frequency (PRF) of 10 Hz and an inter-pulse period (IPP) of 50 milliseconds. Targets are positioned within the acoustic scene at slant range of two to ten meters on grass, dirt or gravel surfaces, and with and without intervening metallic chain link fencing. Acoustic image reconstruction results in means for literal interpretation and quantifiable analyses. A rudimentary technique characterizes acoustic scatter at the ground surfaces. Targets within the acoustic scene are first digitally spotlighted and further processed, providing frequency and aspect angle dependent signature information.

  11. Acoustic reciprocity of spatial coherence in ultrasound imaging.

    PubMed

    Bottenus, Nick; stner, Kutay F

    2015-05-01

    A conventional ultrasound image is formed by transmitting a focused wave into tissue, time-shifting the backscattered echoes received on an array transducer, and summing the resulting signals. The van Cittert-Zernike theorem predicts a particular similarity, or coherence, of these focused signals across the receiving array. Many groups have used an estimate of the coherence to augment or replace the B-mode image in an effort to suppress noise and stationary clutter echo signals, but this measurement requires access to individual receive channel data. Most clinical systems have efficient pipelines for producing focused and summed RF data without any direct way to individually address the receive channels. We describe a method for performing coherence measurements that is more accessible for a wide range of coherence-based imaging. The reciprocity of the transmit and receive apertures in the context of coherence is derived and equivalence of the coherence function is validated experimentally using a research scanner. The proposed method is implemented on a commercial ultrasound system and in vivo short-lag spatial coherence imaging is demonstrated using only summed RF data. The components beyond the acquisition hardware and beamformer necessary to produce a real-time ultrasound coherence imaging system are discussed. PMID:25965679

  12. Acoustic Reciprocity of Spatial Coherence in Ultrasound Imaging

    PubMed Central

    Bottenus, Nick; Üstüner, Kutay F.

    2015-01-01

    A conventional ultrasound image is formed by transmitting a focused wave into tissue, time-shifting the backscattered echoes received on an array transducer and summing the resulting signals. The van Cittert-Zernike theorem predicts a particular similarity, or coherence, of these focused signals across the receiving array. Many groups have used an estimate of the coherence to augment or replace the B-mode image in an effort to suppress noise and stationary clutter echo signals, but this measurement requires access to individual receive channel data. Most clinical systems have efficient pipelines for producing focused and summed RF data without any direct way to individually address the receive channels. We describe a method for performing coherence measurements that is more accessible for a wide range of coherence-based imaging. The reciprocity of the transmit and receive apertures in the context of coherence is derived and equivalence of the coherence function is validated experimentally using a research scanner. The proposed method is implemented on a Siemens ACUSON SC2000™ultrasound system and in vivo short-lag spatial coherence imaging is demonstrated using only summed RF data. The components beyond the acquisition hardware and beamformer necessary to produce a real-time ultrasound coherence imaging system are discussed. PMID:25965679

  13. Imaging textural variation in the acoustoelastic coefficient of aluminum using surface acoustic waves.

    PubMed

    Ellwood, R; Stratoudaki, T; Sharples, S D; Clark, M; Somekh, M G

    2015-11-01

    Much interest has arisen in nonlinear acoustic techniques because of their reported sensitivity to variations in residual stress, fatigue life, and creep damage when compared to traditional linear ultrasonic techniques. However, there is also evidence that the nonlinear acoustic properties are also sensitive to material microstructure. As many industrially relevant materials have a polycrystalline structure, this could potentially complicate the monitoring of material processes when using nonlinear acoustics. Variations in the nonlinear acoustoelastic coefficient on the same length scale as the microstructure of a polycrystalline sample of aluminum are investigated in this paper. This is achieved by the development of a measurement protocol that allows imaging of the acoustoelastic response of a material across a samples surface at the same time as imaging the microstructure. The development, validation, and limitations of this technique are discussed. The nonlinear acoustic response is found to vary spatially by a large factor (>20) between different grains. A relationship is observed when the spatial variation of the acoustoelastic coefficient is compared to the variation in material microstructure. PMID:26627757

  14. ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS

    SciTech Connect

    Thurman E. Scott, Jr., Ph.D.; Younane Abousleiman, Ph.D.; Musharraf Zaman, Ph.D., P.E.

    2001-01-31

    During this phase of the project the research team concentrated on acquisition of acoustic emission data from the high porosity rock samples. The initial experiments indicated that the acoustic emission activity from high porosity Danian chalk were of a very low amplitude. Even though the sample underwent yielding and significant plastic deformation the sample did not generate significant AE activity. This was somewhat surprising. These initial results call into question the validity of attempting to locate AE activity in this weak rock type. As a result the testing program was slightly altered to include measuring the acoustic emission activity from many of the rock types listed in the research program. The preliminary experimental results indicate that AE activity in the sandstones is much higher than in the carbonate rocks (i.e., the chalks and limestones). This observation may be particularly important for planning microseismic imaging of reservoir rocks in the field environment. The preliminary results suggest that microseismic imaging of reservoir rock from acoustic emission activity generated from matrix deformation (during compaction and subsidence) would be extremely difficult to accomplish.

  15. Fluorocarbon nanodrops as acoustic temperature probes.

    PubMed

    Mountford, Paul A; Smith, William S; Borden, Mark A

    2015-10-01

    This work investigated the use of superheated fluorocarbon nanodrops for ultrasound thermal imaging and the use of mixed fluorocarbons for tuning thermal and acoustic thresholds for vaporization. Droplets were fabricated by condensing phospholipid-coated microbubbles containing C3F8 and C4F10 mixed at various molar ratios. Vaporization temperatures first were measured in a closed system by optical transmission following either isothermal pressure release or isobaric heating. The vaporization temperature was found to depend linearly on the percentage of C4F10 in the droplet core, indicating excellent tunability under these fluorocarbon-saturated conditions. Vaporization temperatures were then measured in an open system using contrast-enhanced ultrasound imaging, where it was found that the mixed droplets behaved like pure C4F10 drops. Additionally, the critical mechanical index for vaporization was measured at the limits of therapeutic hyperthermia (37 and 60 C), and again the mixed droplets were found to behave like pure C4F10 drops. These results suggested that C3F8 preferentially dissolves out of the droplet core in open systems, as shown by a simple mass transfer model of multicomponent droplet dissolution. Finally, proof-of-concept was shown that pure C4F10 nanodrops can be used as an acoustic temperature probe. Overall, these results not only demonstrate the potential of superheated fluorocarbon emulsions for sonothermetry but also point to the limits of tunability for fluorocarbon mixtures owing to preferential release of the more soluble species to the atmosphere. PMID:26359919

  16. Resolution estimation and bias reduction in acoustic radiation force impulse imaging

    NASA Astrophysics Data System (ADS)

    Menon, Manoj G.

    Pathological conditions give rise to mechanical changes in tissue that can be exploited for the purpose of diagnosis and treatment of disease. Elasticity imaging is a field developed to creating images of tissue stiffness by mechanically exciting tissue and tracking the tissue response. Acoustic Radiation Force Impulse (ARFI) imaging is one such modality that measures the micron-scale displacements induced in tissue by local acoustic radiation forces using a high intensity ultrasound pulses generated by a standard diagnostic ultrasound scanner. Ultrasound pulses track displacements that are quantified using conventional correlation-based speckle-tracking methods. Generated displacement images can exhibit improved contrast of diseased tissue than conventional ultrasound techniques. In this thesis, the spatial resolution limits of ARFI imaging have been measured using novel simulation and experimental techniques. The full-width, half-maximum (FWHM) of the point-spread function (PSF), a measure of the resolution limit of an imaging system, was extracted by imaging a tissue-mimicking phantom composed of two bonded materials. The ARFI image of the material interface was an estimate of the step response of the system. The ARFI imaging resolution limit was further explored using FEM/acoustic field simulations and linear shift invariant (LSI) models. The ARFI imaging resolution limit was submillimeter, but was highly dependent on imaging parameters. ARFI axial resolution was limited by the correlation window length and tracking pulse parameters. When the correlation window length was less than 1 mm, FEM and LSI models suggest the mechanical response of the tissue influences the resolution, resulting in a larger FWHM than would be predicted by imaging and signal processing parameters alone. ARFI lateral resolution limit corresponded to the lateral two-way beamwidth of the tracking beam. Measuring ARFI imaging resolution capabilities on small phantom inclusions and tissue ablation lesions proved the validity of the step-response based estimated resolution limits on objects of relevant, circular geometry. ARFI imaging resolution was again primarily a function of imaging and signal processing parameters, in good agreement with modulus step phantom derived results. To improve the ability of ARFI imaging to resolve targets near bright boundaries, a method called envelope weighted normalization (EWN) was developed to reduce amplitude modulation of ultrasound signals, thereby reducing displacement estimation bias.

  17. Near-Field Imaging with Sound: An Acoustic STM Model

    ERIC Educational Resources Information Center

    Euler, Manfred

    2012-01-01

    The invention of scanning tunneling microscopy (STM) 30 years ago opened up a visual window to the nano-world and sparked off a bunch of new methods for investigating and controlling matter and its transformations at the atomic and molecular level. However, an adequate theoretical understanding of the method is demanding; STM images can be…

  18. Near-Field Imaging with Sound: An Acoustic STM Model

    ERIC Educational Resources Information Center

    Euler, Manfred

    2012-01-01

    The invention of scanning tunneling microscopy (STM) 30 years ago opened up a visual window to the nano-world and sparked off a bunch of new methods for investigating and controlling matter and its transformations at the atomic and molecular level. However, an adequate theoretical understanding of the method is demanding; STM images can be

  19. Finite Difference Time Domain Analysis of Underwater Acoustic Lens System for Ambient Noise Imaging

    NASA Astrophysics Data System (ADS)

    Mori, Kazuyoshi; Miyazaki, Ayano; Ogasawara, Hanako; Yokoyama, Tomoki; Nakamura, Toshiaki

    2006-05-01

    Much attention has been paid to the new idea of detecting objects using ocean ambient noise. This concept is called ambient noise imaging (ANI). In this study, sound fields focused by an acoustic lens system constructed with a single biconcave lens were analyzed using the finite difference time domain (FDTD) method for realizing an ANI system. The size of the lens aperture that would have sufficient resolutionfor example, the beam width is 1 at 60 kHzwas roughly determined by comparing the image points and -3 dB areas of sound pressure fields generated by lenses with various apertures. Then, in another FDTD analysis, we successfully used a lens with a determined aperture to detect rigid target objects in an acoustic noise field generated by a large number of point sources.

  20. Underwater Acoustic Matched Field Imaging Based on Compressed Sensing.

    PubMed

    Yan, Huichen; Xu, Jia; Long, Teng; Zhang, Xudong

    2015-01-01

    Matched field processing (MFP) is an effective method for underwater target imaging and localizing, but its performance is not guaranteed due to the nonuniqueness and instability problems caused by the underdetermined essence of MFP. By exploiting the sparsity of the targets in an imaging area, this paper proposes a compressive sensing MFP (CS-MFP) model from wave propagation theory by using randomly deployed sensors. In addition, the model's recovery performance is investigated by exploring the lower bounds of the coherence parameter of the CS dictionary. Furthermore, this paper analyzes the robustness of CS-MFP with respect to the displacement of the sensors. Subsequently, a coherence-excluding coherence optimized orthogonal matching pursuit (CCOOMP) algorithm is proposed to overcome the high coherent dictionary problem in special cases. Finally, some numerical experiments are provided to demonstrate the effectiveness of the proposed CS-MFP method. PMID:26457708

  1. Underwater Acoustic Matched Field Imaging Based on Compressed Sensing

    PubMed Central

    Yan, Huichen; Xu, Jia; Long, Teng; Zhang, Xudong

    2015-01-01

    Matched field processing (MFP) is an effective method for underwater target imaging and localizing, but its performance is not guaranteed due to the nonuniqueness and instability problems caused by the underdetermined essence of MFP. By exploiting the sparsity of the targets in an imaging area, this paper proposes a compressive sensing MFP (CS-MFP) model from wave propagation theory by using randomly deployed sensors. In addition, the model’s recovery performance is investigated by exploring the lower bounds of the coherence parameter of the CS dictionary. Furthermore, this paper analyzes the robustness of CS-MFP with respect to the displacement of the sensors. Subsequently, a coherence-excluding coherence optimized orthogonal matching pursuit (CCOOMP) algorithm is proposed to overcome the high coherent dictionary problem in special cases. Finally, some numerical experiments are provided to demonstrate the effectiveness of the proposed CS-MFP method. PMID:26457708

  2. Hepatic Steatosis: Assessment with Acoustic Structure Quantification of US Imaging.

    PubMed

    Son, Jee-Young; Lee, Jae Young; Yi, Nam-Joon; Lee, Kwang-Woong; Suh, Kyung-Suk; Kim, Kwang Gi; Lee, Jeong Min; Han, Joon Koo; Choi, Byung Ihn

    2016-01-01

    Purpose To investigate the diagnostic performance of acoustic structure quantification (ASQ) for the assessment of hepatic steatosis by using hydrogen 1 ((1)H) magnetic resonance (MR) spectroscopy as the reference standard and to compare ASQ with hepatorenal ratio. Materials and Methods This prospective study was approved by an institutional review board, and informed written consent was obtained from all participants. ASQ and MR spectroscopy were performed in 89 participants (mean age, 41.48 years 14.16; 35 men, 54 women) without history of chronic liver disease. Obtained were focal disturbance (FD) ratio by using ASQ, hepatic fat fraction (HFF) by using MR spectroscopy, and hepatorenal ratio by using a histogram. Correlation coefficient, intraclass correlation coefficient, and receiver operating curve analyses were performed. Results FD ratio measured with ASQ had a strong linear correlation with HFF measured with MR spectroscopy after logarithmic transformation of both variables (r = -0.87; P < .001). By using HFF of 5.79% as a cutoff value of 10% hepatic steatosis, 29 of 89 participants (32.6%) were categorized into the group with hepatic steatosis of 10% or greater (mean HFF, 13.18% 4.89). The area under curve of the FD ratio for diagnosing hepatic steatosis 10% or greater was 0.959 (95% confidence interval: 0.895, 0.990) with sensitivity of 86.2% (95% confidence interval: 68.3%, 96.0%) and specificity of 100% (95% confidence interval: 94.0%, 100.0%) by using a cutoff value of 0.1; the area under curve and specificity of the FD ratio were significantly higher than those of the hepatorenal ratio (respectively, 0.772 and 73.3%; respective P values, .001 and <.001). Conclusion This pilot study in a cohort of patients with hepatic steatosis without other parenchymal disease suggested ASQ may be valuable for the quantification of hepatic steatosis and detection of hepatic steatosis 10% or greater in living liver donors. () RSNA, 2015. PMID:26121121

  3. Three-Dimensional Acoustic Tissue Model: A Computational Tissue Phantom for Image Analyses

    NASA Astrophysics Data System (ADS)

    Mamou, J.; Oelze, M. L.; O'Brien, W. D.; Zachary, J. F.

    A novel methodology to obtain three-dimensional (3D) acoustic tissue models (3DATMs) is introduced. 3DATMs can be used as computational tools for ultrasonic imaging algorithm development and analysis. In particular, 3D models of biological structures can provide great benefit to better understand fundamentally how ultrasonic waves interact with biological materials. As an example, such models were used to generate ultrasonic images that characterize tumor tissue microstructures. 3DATMs can be used to evaluate a variety of tissue types. Typically, excised tissue is fixed, embedded, serially sectioned, and stained. The stained sections are digitally imaged (24-bit bitmap) with light microscopy. Contrast of each stained section is equalized and an automated registration algorithm aligns consecutive sections. The normalized mutual information is used as a similarity measure, and simplex optimization is conducted to find the best alignment. Both rigid and non-rigid registrations are performed. During tissue preparation, some sections are generally lost; thus, interpolation prior to 3D reconstruction is performed. Interpolation is conducted after registration using cubic Hermite polynoms. The registered (with interpolated) sections yield a 3D histologic volume (3DHV). Acoustic properties are then assigned to each tissue constituent of the 3DHV to obtain the 3DATMs. As an example, a 3D acoustic impedance tissue model (3DZM) was obtained for a solid breast tumor (EHS mouse sarcoma) and used to estimate ultrasonic scatterer size. The 3DZM results yielded an effective scatterer size of 32.9 (6.1) ?m. Ultrasonic backscatter measurements conducted on the same tumor tissue in vivo yielded an effective scatterer size of 33 (8) ?m. This good agreement shows that 3DATMs may be a powerful modeling tool for acoustic imaging applications

  4. Acoustic output of multi-line transmit beamforming for fast cardiac imaging: a simulation study.

    PubMed

    Santos, Pedro; Tong, Ling; Ortega, Alejandra; Lvstakken, Lasse; Samset, Eigil; D'hooge, Jan

    2015-07-01

    Achieving higher frame rates in cardiac ultrasound could unveil short-lived myocardial events and lead to new insights on cardiac function. Multi-line transmit (MLT) beamforming (i.e., simultaneously transmitting multiple focused beams) is a potential approach to achieve this. However, two challenges come with it: first, it leads to cross-talk between the MLT beams, appearing as imaging artifacts, and second, it presents acoustic summation in the near field, where multiple MLT beams overlap. Although several studies have focused on the former, no studies have looked into the implications of the latter on acoustic safety. In this paper, the acoustic field of 4-MLT was simulated and compared with single-line transmit (SLT). The findings suggest that standard MLT does present potential concerns. Compared with SLT, it shows a 2-fold increase in mechanical index (MI) (from 1.0 to 2.3), a 6-fold increase in spatial-peak pulse-average intensity (I(sppa)) (from 99 to 576 W?cm(-2)) and a 12-fold increase in spatial-peak temporalaverage intensity (I(spta)) (from 119 to 1407 mW?cm(-2)). Subsequently, modifications of the transmit pulse and delay line of MLT were studied. These modifications allowed for a change in the spatio-temporal distribution of the acoustic output, thereby significantly decreasing the safety indices (MI = 1.2, I(sppa) = 92 W?cm(-2) and I(spta) = 366 mW?cm(-2)). Accordingly, they help mitigate the concerns around MLT, reducing potential tradeoffs between acoustic safety and image quality. PMID:26168178

  5. Finite element modelling for the investigation of edge effect in acoustic micro imaging of microelectronic packages

    NASA Astrophysics Data System (ADS)

    Shen Lee, Chean; Zhang, Guang-Ming; Harvey, David M.; Ma, Hong-Wei; Braden, Derek R.

    2016-02-01

    In acoustic micro imaging of microelectronic packages, edge effect is often presented as artifacts of C-scan images, which may potentially obscure the detection of defects such as cracks and voids in the solder joints. The cause of edge effect is debatable. In this paper, a 2D finite element model is developed on the basis of acoustic micro imaging of a flip-chip package using a 230 MHz focused transducer to investigate acoustic propagation inside the package in attempt to elucidate the fundamental mechanism that causes the edge effect. A virtual transducer is designed in the finite element model to reduce the coupling fluid domain, and its performance is characterised against the physical transducer specification. The numerical results showed that the under bump metallization (UBM) structure inside the package has a significant impact on the edge effect. Simulated wavefields also showed that the edge effect is mainly attributed to the horizontal scatter, which is observed in the interface of silicon die-to-the outer radius of solder bump. The horizontal scatter occurs even for a flip-chip package without the UBM structure.

  6. A magnetic resonance imaging study on the articulatory and acoustic speech parameters of Malay vowels

    PubMed Central

    2014-01-01

    The phonetic properties of six Malay vowels are investigated using magnetic resonance imaging (MRI) to visualize the vocal tract in order to obtain dynamic articulatory parameters during speech production. To resolve image blurring due to the tongue movement during the scanning process, a method based on active contour extraction is used to track tongue contours. The proposed method efficiently tracks tongue contours despite the partial blurring of MRI images. Consequently, the articulatory parameters that are effectively measured as tongue movement is observed, and the specific shape of the tongue and its position for all six uttered Malay vowels are determined. Speech rehabilitation procedure demands some kind of visual perceivable prototype of speech articulation. To investigate the validity of the measured articulatory parameters based on acoustic theory of speech production, an acoustic analysis based on the uttered vowels by subjects has been performed. As the acoustic speech and articulatory parameters of uttered speech were examined, a correlation between formant frequencies and articulatory parameters was observed. The experiments reported a positive correlation between the constriction location of the tongue body and the first formant frequency, as well as a negative correlation between the constriction location of the tongue tip and the second formant frequency. The results demonstrate that the proposed method is an effective tool for the dynamic study of speech production. PMID:25060583

  7. A magnetic resonance imaging study on the articulatory and acoustic speech parameters of Malay vowels.

    PubMed

    Zourmand, Alireza; Mirhassani, Seyed Mostafa; Ting, Hua-Nong; Bux, Shaik Ismail; Ng, Kwan Hoong; Bilgen, Mehmet; Jalaludin, Mohd Amin

    2014-01-01

    The phonetic properties of six Malay vowels are investigated using magnetic resonance imaging (MRI) to visualize the vocal tract in order to obtain dynamic articulatory parameters during speech production. To resolve image blurring due to the tongue movement during the scanning process, a method based on active contour extraction is used to track tongue contours. The proposed method efficiently tracks tongue contours despite the partial blurring of MRI images. Consequently, the articulatory parameters that are effectively measured as tongue movement is observed, and the specific shape of the tongue and its position for all six uttered Malay vowels are determined.Speech rehabilitation procedure demands some kind of visual perceivable prototype of speech articulation. To investigate the validity of the measured articulatory parameters based on acoustic theory of speech production, an acoustic analysis based on the uttered vowels by subjects has been performed. As the acoustic speech and articulatory parameters of uttered speech were examined, a correlation between formant frequencies and articulatory parameters was observed. The experiments reported a positive correlation between the constriction location of the tongue body and the first formant frequency, as well as a negative correlation between the constriction location of the tongue tip and the second formant frequency. The results demonstrate that the proposed method is an effective tool for the dynamic study of speech production. PMID:25060583

  8. Acoustical standards in engineering acoustics

    NASA Astrophysics Data System (ADS)

    Burkhard, Mahlon D.

    2001-05-01

    The Engineering Acoustics Technical Committee is concerned with the evolution and improvement of acoustical techniques and apparatus, and with the promotion of new applications of acoustics. As cited in the Membership Directory and Handbook (2002), the interest areas include transducers and arrays; underwater acoustic systems; acoustical instrumentation and monitoring; applied sonics, promotion of useful effects, information gathering and transmission; audio engineering; acoustic holography and acoustic imaging; acoustic signal processing (equipment and techniques); and ultrasound and infrasound. Evident connections between engineering and standards are needs for calibration, consistent terminology, uniform presentation of data, reference levels, or design targets for product development. Thus for the acoustical engineer standards are both a tool for practices, for communication, and for comparison of his efforts with those of others. Development of many standards depends on knowledge of the way products are put together for the market place and acoustical engineers provide important input to the development of standards. Acoustical engineers and members of the Engineering Acoustics arm of the Society both benefit from and contribute to the Acoustical Standards of the Acoustical Society.

  9. Acoustic property reconstruction of a pygmy sperm whale (Kogia breviceps) forehead based on computed tomography imaging.

    PubMed

    Song, Zhongchang; Xu, Xiao; Dong, Jianchen; Xing, Luru; Zhang, Meng; Liu, Xuecheng; Zhang, Yu; Li, Songhai; Berggren, Per

    2015-11-01

    Computed tomography (CT) imaging and sound experimental measurements were used to reconstruct the acoustic properties (density, velocity, and impedance) of the forehead tissues of a deceased pygmy sperm whale (Kogia breviceps). The forehead was segmented along the body axis and sectioned into cross section slices, which were further cut into sample pieces for measurements. Hounsfield units (HUs) of the corresponding measured pieces were obtained from CT scans, and regression analyses were conducted to investigate the linear relationships between the tissues' HUs and velocity, and HUs and density. The distributions of the acoustic properties of the head at axial, coronal, and sagittal cross sections were reconstructed, revealing that the nasal passage system was asymmetric and the cornucopia-shaped spermaceti organ was in the right nasal passage, surrounded by tissues and airsacs. A distinct dense theca was discovered in the posterior-dorsal area of the melon, which was characterized by low velocity in the inner core and high velocity in the outer region. Statistical analyses revealed significant differences in density, velocity, and acoustic impedance between all four structures, melon, spermaceti organ, muscle, and connective tissue (p < 0.001). The obtained acoustic properties of the forehead tissues provide important information for understanding the species' bioacoustic characteristics. PMID:26627786

  10. Applications of stereoscopic particle image velocimetry: Dust acoustic waves and velocity space distribution functions

    SciTech Connect

    Thomas, Edward Jr.; Williams, Jeremiah

    2006-05-15

    Two-dimensional particle image velocimetry (2D-PIV) techniques have been applied to dusty plasmas for the past 5 years. During that time, 2D-PIV has been used to provide detailed measurements of microparticle transport in dusty plasmas. However, a measurement of the third velocity vector direction is necessary to fully understand the microparticle transport. In this paper, stereoscopic particle image velocimetry (stereo-PIV) is used as a technique for obtaining all three-velocity vector components. This paper discusses the application of stereo-PIV techniques to measurements of dust acoustic waves and velocity space distribution functions in dusty plasmas.

  11. Resonant acoustic nonlinearity for defect-selective imaging and NDT

    NASA Astrophysics Data System (ADS)

    Solodov, Igor

    2015-10-01

    The bottleneck problem of nonlinear NDT is a low efficiency of conversion from fundamental frequency to nonlinear frequency components. In this paper, it is proposed to use a combination of mechanical resonance and nonlinearity of defects to enhance the input-output conversion. The concept of the defect as a nonlinear oscillator brings about new dynamic and frequency scenarios characteristic of parametric oscillations. The modes observed in experiment include sub- and superharmonic resonances with anomalously efficient generation of the higher harmonics and subharmonics. A modified version of the superharmonic resonance (combination frequency resonance) is used to enhance the efficiency of frequency mixing mode of nonlinear NDT. All the resonant nonlinear modes are strongly localized in the defect area that provides a background for high-contrast highly-sensitive defect- and frequency-selective imaging.

  12. A comparison of traffic estimates of nocturnal flying animals using radar, thermal imaging, and acoustic recording.

    PubMed

    Horton, Kyle G; Shriver, W Gregory; Buler, Jeffrey J

    2015-03-01

    There are several remote-sensing tools readily available for the study of nocturnally flying animals (e.g., migrating birds), each possessing unique measurement biases. We used three tools (weather surveillance radar, thermal infrared camera, and acoustic recorder) to measure temporal and spatial patterns of nocturnal traffic estimates of flying animals during the spring and fall of 2011 and 2012 in Lewes, Delaware, USA. Our objective was to compare measures among different technologies to better understand their animal detection biases. For radar and thermal imaging, the greatest observed traffic rate tended to occur at, or shortly after, evening twilight, whereas for the acoustic recorder, peak bird flight-calling activity was observed just prior to morning twilight. Comparing traffic rates during the night for all seasons, we found that mean nightly correlations between acoustics and the other two tools were weakly correlated (thermal infrared camera and acoustics, r = 0.004 ± 0.04 SE, n = 100 nights; radar and acoustics, r = 0.14 ± 0.04 SE, n = 101 nights), but highly variable on an individual nightly basis (range = -0.84 to 0.92, range = -0.73 to 0.94). The mean nightly correlations between traffic rates estimated by radar and by thermal infrared camera during the night were more strongly positively correlated (r = 0.39 ± 0.04 SE, n = 125 nights), but also were highly variable for individual nights (range = -0.76 to 0.98). Through comparison with radar data among numerous height intervals, we determined that flying animal height above the ground influenced thermal imaging positively and flight call detections negatively. Moreover, thermal imaging detections decreased with the presence of cloud cover and increased with mean ground flight speed of animals, whereas acoustic detections showed no relationship with cloud cover presence but did decrease with increased flight speed. We found sampling methods to be positively correlated when comparing mean nightly traffic rates across nights. The strength of these correlations generally increased throughout the night, peaking 2-3 hours before morning twilight. Given the convergence of measures by different tools at this time, we suggest that researchers consider sampling flight activity in the hours before morning twilight when differences due to detection biases among sampling tools appear to be minimized. PMID:26263662

  13. Lower-Limb Vascular Imaging with Acoustic Radiation Force Elastography: Demonstration of In Vivo Feasibility

    PubMed Central

    Dumont, Douglas; Dahl, Jeremy; Miller, Elizabeth; Allen, Jason; Fahey, Brian; Trahey, Gregg

    2010-01-01

    Acoustic radiation force impulse (ARFI) imaging characterizes the mechanical properties of tissue by measuring displacement resulting from applied ultrasonic radiation force. In this paper, we describe the current status of ARFI imaging for lower-limb vascular applications and present results from both tissue-mimicking phantoms and in vivo experiments. Initial experiments were performed on vascular phantoms constructed with polyvinyl alcohol for basic evaluation of the modality. Multilayer vessels and vessels with compliant occlusions of varying plaque load were evaluated with ARFI imaging techniques. Phantom layers and plaque are well resolved in the ARFI images, with higher contrast than B-mode, demonstrating the ability of ARFI imaging to identify regions of different mechanical properties. Healthy human subjects and those with diagnosed lower-limb peripheral arterial disease were imaged. Proximal and distal vascular walls are well visualized in ARFI images, with higher mean contrast than corresponding B-mode images. ARFI images reveal information not observed by conventional ultrasound and lend confidence to the feasibility of using ARFI imaging during lower-limb vascular workup. PMID:19473912

  14. Contrast-enhanced magneto-photo-acoustic imaging in vivo using dual-contrast nanoparticles?

    PubMed Central

    Qu, Min; Mehrmohammadi, Mohammad; Truby, Ryan; Graf, Iulia; Homan, Kimberly; Emelianov, Stanislav

    2014-01-01

    By mapping the distribution of targeted plasmonic nanoparticles (NPs), photoacoustic (PA) imaging offers the potential to detect the pathologies in the early stages. However, optical absorption of the endogenous chromophores in the background tissue significantly reduces the contrast resolution of photoacoustic imaging. Previously, we introduced MPA imaging a synergistic combination of magneto-motive ultrasound (MMUS) and PA imaging, and demonstrated MPA contrast enhancement using cell culture studies. In the current study, contrast enhancement was investigated in vivo using the magneto-photo-acoustic (MPA) imaging augmented with dual-contrast nanoparticles. Liposomal nanoparticles (LNPs) possessing both optical absorption and magnetic properties were injected into a murine tumor model. First, photoacoustic signals were generated from both the endogenous absorbers in the tissue and the liposomal nanoparticles in the tumor. Then, given significant differences in magnetic properties of tissue and LNPs, the magnetic response of LNPs (i.e. MMUS signal) was utilized to suppress the unwanted PA signals from the background tissue thus improving the PA imaging contrast. In this study, we demonstrated the 3D MPA imaging of LNP-labeled xenografted tumor in a live animal. Compared to conventional PA imaging, the MPA imaging show significantly enhanced contrast between the nanoparticle-labeled tumor and the background tissue. Our results suggest the feasibility of MPA imaging for high contrast in vivo mapping of dual-contrast nanoparticles. PMID:24653976

  15. The coordination chemistry and magnetism of some 3d-4f and 4f amino-polyalcohol compounds.

    PubMed

    Sharples, Joseph W; Collison, David

    2014-02-01

    Triethanolamine, teaH3, and diethanolamine, RdeaH2, 3d-4f and 4f compounds demonstrate an enormous variety in their structure and bonding. This review examines the synthetic strategies to these molecules and their magnetic properties, whilst trying to assess these ligands' suitability towards new SMMs and magnetic refrigerants. PMID:25009361

  16. The coordination chemistry and magnetism of some 3d–4f and 4f amino-polyalcohol compounds

    PubMed Central

    Sharples, Joseph W.; Collison, David

    2014-01-01

    Triethanolamine, teaH3, and diethanolamine, RdeaH2, 3d–4f and 4f compounds demonstrate an enormous variety in their structure and bonding. This review examines the synthetic strategies to these molecules and their magnetic properties, whilst trying to assess these ligands’ suitability towards new SMMs and magnetic refrigerants. PMID:25009361

  17. Eigenfunction analysis of stochastic backscatter for characterization of acoustic aberration in medical ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Varslot, Trond; Krogstad, Harald; Mo, Eirik; Angelsen, Bjrn A.

    2004-06-01

    Presented here is a characterization of aberration in medical ultrasound imaging. The characterization is optimal in the sense of maximizing the expected energy in a modified beamformer output of the received acoustic backscatter. Aberration correction based on this characterization takes the form of an aberration correction filter. The situation considered is frequently found in applications when imaging organs through a body wall: aberration is introduced in a layer close to the transducer, and acoustic backscatter from a scattering region behind the body wall is measured at the transducer surface. The scattering region consists of scatterers randomly distributed with very short correlation length compared to the acoustic wavelength of the transmit pulse. The scatterer distribution is therefore assumed to be ? correlated. This paper shows how maximizing the expected energy in a modified beamformer output signal naturally leads to eigenfunctions of a Fredholm integral operator, where the associated kernel function is a spatial correlation function of the received stochastic signal. Aberration characterization and aberration correction are presented for simulated data constructed to mimic aberration introduced by the abdominal wall. The results compare well with what is obtainable using data from a simulated point source.

  18. Symmetry analysis for nonlinear time reversal methods applied to nonlinear acoustic imaging

    NASA Astrophysics Data System (ADS)

    Dos Santos, Serge; Chaline, Jennifer

    2015-10-01

    Using symmetry invariance, nonlinear Time Reversal (TR) and reciprocity properties, the classical NEWS methods are supplemented and improved by new excitations having the intrinsic property of enlarging frequency analysis bandwidth and time domain scales, with now both medical acoustics and electromagnetic applications. The analysis of invariant quantities is a well-known tool which is often used in nonlinear acoustics in order to simplify complex equations. Based on a fundamental physical principle known as symmetry analysis, this approach consists in finding judicious variables, intrinsically scale dependant, and able to describe all stages of behaviour on the same theoretical foundation. Based on previously published results within the nonlinear acoustic areas, some practical implementation will be proposed as a new way to define TR-NEWS based methods applied to NDT and medical bubble based non-destructive imaging. This paper tends to show how symmetry analysis can help us to define new methodologies and new experimental set-up involving modern signal processing tools. Some example of practical realizations will be proposed in the context of biomedical non-destructive imaging using Ultrasound Contrast Agents (ACUs) where symmetry and invariance properties allow us to define a microscopic scale-invariant experimental set-up describing intrinsic symmetries of the microscopic complex system.

  19. Progress on developing acoustic-infrared imaging NDE: studying motions in crack faces

    NASA Astrophysics Data System (ADS)

    Han, Xiaoyan; Islam, Md. S.

    2010-04-01

    In this paper, we present our progress in the CAREER project "Investigation of Hybrid Acoustic-Infrared NDE Imaging Mechanisms" supported by NSF Civil, Mechanical & Manufacturing Innovation Division, Sensors & Sensing Systems program directed by Dr. Shih-Chi Liu. The project ended in September, 2009. During the project, the PIs and her graduate students had investigated on several aspects of the innovative Sonic Infrared Imaging technology. Sonic Infrared Imaging is a novel technique which implements the concept of combining infrared (IR) sensing and imaging with pulsed (typically a fraction of a second) sonic/ultrasonic excitation. This technique has significant advantages over traditional NDE techniques as an effective, fast, and wide-area NDE method. The PI has studied the fundamental issues related to this technology, such as the non-linear vibration behavior induced in the target materials and structures through both experimental study and theoretical calculation.

  20. ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS

    SciTech Connect

    Thurman E. Scott, Jr., Ph.D.; Younane Abousleiman, Ph.D.; Musharraf Zaman, Ph.D., P.E.

    2002-11-18

    During the sixth quarter of this research project the research team developed a method and the experimental procedures for acquiring the data needed for ultrasonic tomography of rock core samples under triaxial stress conditions as outlined in Task 10. Traditional triaxial compression experiments, where compressional and shear wave velocities are measured, provide little or no information about the internal spatial distribution of mechanical damage within the sample. The velocities measured between platen-to-platen or sensor-to-sensor reflects an averaging of all the velocities occurring along that particular raypath across the boundaries of the rock. The research team is attempting to develop and refine a laboratory equivalent of seismic tomography for use on rock samples deformed under triaxial stress conditions. Seismic tomography, utilized for example in crosswell tomography, allows an imaging of the velocities within a discrete zone within the rock. Ultrasonic or acoustic tomography is essentially the extension of that field technology applied to rock samples deforming in the laboratory at high pressures. This report outlines the technical steps and procedures for developing this technology for use on weak, soft chalk samples. Laboratory tests indicate that the chalk samples exhibit major changes in compressional and shear wave velocities during compaction. Since chalk is the rock type responsible for the severe subsidence and compaction in the North Sea it was selected for the first efforts at tomographic imaging of soft rocks. Field evidence from the North Sea suggests that compaction, which has resulted in over 30 feet of subsidence to date, is heterogeneously distributed within the reservoir. The research team will attempt to image this very process in chalk samples. The initial tomographic studies (Scott et al., 1994a,b; 1998) were accomplished on well cemented, competent rocks such as Berea sandstone. The extension of the technology to weaker samples is more difficult but potentially much more rewarding. The chalk, since it is a weak material, also attenuates wave propagation more than other rock types. Three different types of sensors were considered (and tested) for the tomographic imaging project: 600 KHz PZT, 1 MHz PZT, and PVDF film sensors. 600 KHz PZT crystals were selected because they generated a sufficiently high amplitude pulse to propagate across the damaged chalk. A number of different configurations were considered for placement of the acoustic arrays. It was decided after preliminary testing that the most optimum arrangement of the acoustic sensors was to place three arrays of sensors, with each array containing twenty sensors, around the sample. There would be two horizontal arrays to tomographically image two circular cross-sectional planes through the rock core sample. A third array would be vertically oriented to provide a vertical cross-sectional view of the sample. A total of 260 acoustic raypaths would be shot and acquired in the horizontal acoustic array to create each horizontal tomographic image. The sensors can be used as both acoustic sources or as acoustic each of the 10 pulsers to the 10 receivers.

  1. Acoustic Image Models for Obstacle Avoidance with Forward-Looking Sonar

    NASA Astrophysics Data System (ADS)

    Masek, T.; Klsch, M.

    Long-range forward-looking sonars (FLS) have recently been deployed in autonomous unmanned vehicles (AUV). We present models for various features in acoustic images, with the goal of using this sensor for altitude maintenance, obstacle detection and obstacle avoidance. First, we model the backscatter and FLS noise as pixel-based, spatially-varying intensity distributions. Experiments show that these models predict noise with an accuracy of over 98%. Next, the presence of acoustic noise from two other sources including a modem is reliably detected with a template-based filter and a threshold learned from training data. Lastly, the ocean floor location and orientation is estimated with a gradient-descent method using a site-independent template, yielding sufficiently accurate results in 95% of the frames. Temporal information is expected to further improve the performance.

  2. ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS

    SciTech Connect

    Thurman E. Scott, Jr., Ph.D.; Younane Abousleiman, Ph.D.; Musharraf Zaman, Ph.D., P.E.

    2002-11-18

    During the seven quarter of the project the research team analyzed some of the acoustic velocity data and rock deformation data. The goal is to create a series of ''deformation-velocity maps'' which can outline the types of rock deformational mechanisms which can occur at high pressures and then associate those with specific compressional or shear wave velocity signatures. During this quarter, we began to analyze both the acoustical and deformational properties of the various rock types. Some of the preliminary velocity data from the Danian chalk will be presented in this report. This rock type was selected for the initial efforts as it will be used in the tomographic imaging study outlined in Task 10. This is one of the more important rock types in the study as the Danian chalk is thought to represent an excellent analog to the Ekofisk chalk that has caused so many problems in the North Sea. Some of the preliminary acoustic velocity data obtained during this phase of the project indicates that during pore collapse and compaction of this chalk, the acoustic velocities can change by as much as 200 m/s. Theoretically, this significant velocity change should be detectable during repeated successive 3-D seismic images. In addition, research continues with an analysis of the unconsolidated sand samples at high confining pressures obtained in Task 9. The analysis of the results indicate that sands with 10% volume of fines can undergo liquefaction at lower stress conditions than sand samples which do not have fines added. This liquefaction and/or sand flow is similar to ''shallow water'' flows observed during drilling in the offshore Gulf of Mexico.

  3. 4f electron delocalization and volume collapse in praseodymium metal

    NASA Astrophysics Data System (ADS)

    Bradley, Joseph A.; Moore, Kevin T.; Lipp, Magnus J.; Mattern, Brian A.; Pacold, Joseph I.; Seidler, Gerald T.; Chow, Paul; Rod, Eric; Xiao, Yuming; Evans, William J.

    2012-03-01

    We study the pressure evolution of the 4f electrons in elemental praseodymium metal compressed through several crystallographic phases, including the large volume-collapse transition at 20 GPa. Using resonant x-ray emission, we directly and quantitatively measure the development of multiple electronic configurations with differing 4f occupation numbers, the key quantum observable related to the delocalization of the strongly correlated 4f electrons. These results provide a high-fidelity test of prior predictions by dynamical mean-field theory, and support the hypothesis of a strong connection between electronic and structural degrees of freedom at the volume-collapse transition.

  4. 4f electron delocalization and volume collapse in praseodymium metal

    SciTech Connect

    Bradley, Joseph A.; Moore, Kevin T.; Lipp, Magnus J.; Mattern, Brian A.; Pacold, Joseph I.; Seidler, Gerald T.; Chow, Paul; Rod, Eric; Xiao, Yuming; Evans, William J.

    2012-04-17

    We study the pressure evolution of the 4f electrons in elemental praseodymium metal compressed through several crystallographic phases, including the large volume-collapse transition at 20 GPa. Using resonant x-ray emission, we directly and quantitatively measure the development of multiple electronic configurations with differing 4f occupation numbers, the key quantum observable related to the delocalization of the strongly correlated 4f electrons. These results provide a high-fidelity test of prior predictions by dynamical mean-field theory, and support the hypothesis of a strong connection between electronic and structural degrees of freedom at the volume-collapse transition.

  5. Signal Processing for Time-Lapse Cell Imaging with Vector-Contrast Scanning Acoustic Microscopy

    NASA Astrophysics Data System (ADS)

    von Buttlar, M.; Mohamed, E. A.; Grill, W.

    Non-invasive and marker-free monitoring of living cells can be accomplished by vector contrast scanning acoustic microscopy. In this paper, the signal processing required for creating time-lapse movies of mesenchymal stem cells is discussed. This includes electronic signal processing, autofocusing and image processing. Prior to each recorded image the focusing transducer is moved away from the sample until no echo signal is received. This allows direct measurement of the offset vector caused by internal lens echoes. The offset vector can then be subtracted from the following vector-contrast image. For subsequent autofocusing the transducer is moved closer to the sample until the maximum of the signal in reflection is passed. The transducer position for the maximum reflected signal is determined by respective software and adjusted accordingly. Autofocusing is a requirement for tiled scans where a piezo-scanner and an automatic microscope stage are combined to increase the field of view. As there are typically thousands of images involved in a single movie, batch image processing routines are required. Customized plugins for ImageJ were developed to combine specialized functions for vector contrast data processing with standard image processing capabilities. The motility of a population of ovine mesenchymal stem cells was continuously recorded for 8 h. The detection scheme including experimental details is presented and applications including time-lapse imaging are demonstrated and discussed.

  6. Using numerical models and volume rendering to interpret acoustic imaging of hydrothermal flow

    NASA Astrophysics Data System (ADS)

    Bemis, K. G.; Bennett, K.; Takle, J.; Rona, P. A.; Silver, D.

    2009-12-01

    Our acoustic imaging system will be installed onto the Neptune Canada observatory at the Main Endeavour Field, Juan de Fuca Ridge, which is a Ridge 2000 Integrated Study Site. Thereafter, 16-30 Gb of acoustic imaging data will be collected daily. We are developing a numerical model of merging plumes that will be used to guide expectations and volume rendering software that transforms volumetric acoustic data into photo-like images. Hydrothermal flow is modeled as a combination of merged point sources which can be configured in any geometry. The model stipulates the dissipation or dilution of the flow and uses potential fields and complex analysis to combine the entrainment fields produced by each source. The strengths of this model are (a) the ability to handle a variety of scales especially the small scale as the potential fields can be specified with an effectively infinite boundary condition, (b) the ability to handle line, circle and areal source configurations, and (c) the ability to handle both high temperature focused flow and low temperature diffuse flow. This model predicts the vertical and horizontal velocities and the spatial distribution of effluent from combined sources of variable strength in a steady ambient velocity field. To verify the accuracy of the models results, we compare the model predictions of plume centerlines for the merging of two relatively strong point sources with the acoustic imaging data collected at Clam Acres, Southwest Vent Field, EPR 21N in 1990. The two chimneys are 3.5 m apart and the plumes emanating from their tops merge approximately 18 mab. The model is able to predict the height of merging and the bending of the centerlines. Merging is implicitly observed at Grotto Vent, Main Endeavour Field, in our VIP 2000 data from July 2000: although there are at least 5 vigorous black smokers only a single plume is discernable in the acoustic imaging data. Furthermore, the observed Doppler velocity data increases with height, consistent with multiple merging plumes. The numerical model assumes 5 sources in a circle and predicts that the plumes merge between 10 m and 15 m above the vents resulting in a 3-fold increase in velocity. The predictions of the numerical model are sensitive to the interplay between vent velocity, ambient velocity and entrainment rates. To better illustrate variations in expansion with ambient velocity, we have developed a two-phase volume rendering technique which substantially improves the illustration of expansion rates. The numerical model is also able to make predictions about the areal distribution of effluent from diffuse flow by modeling it as multiple weak sources. Comparisons with diffuse flow maps, particularly those based on July 2000 data from our acoustic imaging, suggest that interpretation of diffuse flow maps (and in situ temperature measurements) requires knowledge of the ambient currents in order to gauge how far the effluent may have shifted from its source, as merging may result in an increase in rise rate.

  7. Ultrasound-Stimulated Acoustic Emission in Thermal Image-Guided HIFU Therapy: A Phantom Study

    SciTech Connect

    Jiang, C. P.; Lin, W. T.; Chen, W. S.

    2006-05-08

    Magnetic resonance image (MRI) is a promising monitoring tool for non-invasive real-time thermal guidance in high intensity focused ultrasound (HIFU) during thermal ablation surgery. However, this approach has two main drawbacks: 1) majority of components need to be redesigned to be MR compatible in order to avoid effecting MR images, and 2) the cost of operating MRI facilities is high. Alternately, ultrasound-stimulated acoustic emission (USAE) method has been applied for detecting thermal variations in tissues. An optical transparent phantom, made from polyacrylamide, containing thermal sensitive indicator protein (Bovine Serum Albumin), was prepared for observing the HIFU-induced denaturalization. A thermal-couple was set up for validation of temperature distribution. Experimental results show that thermal image can be captured clearly under stationary conditions.

  8. Sensing the delivery and endocytosis of nanoparticles using magneto-photo-acoustic imaging

    PubMed Central

    Qu, M.; Mehrmohammadi, M.; Emelianov, S.Y.

    2015-01-01

    Many biomedical applications necessitate a targeted intracellular delivery of the nanomaterial to specific cells. Therefore, a non-invasive and reliable imaging tool is required to detect both the delivery and cellular endocytosis of the nanoparticles. Herein, we demonstrate that magneto-photo-acoustic (MPA) imaging can be used to monitor the delivery and to identify endocytosis of magnetic and optically absorbing nanoparticles. The relationship between photoacoustic (PA) and magneto-motive ultrasound (MMUS) signals from the in vitro samples were analyzed to identify the delivery and endocytosis of nanoparticles. The results indicated that during the delivery of nanoparticles to the vicinity of the cells, both PA and MMUS signals are almost linearly proportional. However, accumulation of nanoparticles within the cells leads to nonlinear MMUS-PA relationship, due to non-linear MMUS signal amplification. Therefore, through longitudinal MPA imaging, it is possible to monitor the delivery of nanoparticles and identify the endocytosis of the nanoparticles by living cells. PMID:26640773

  9. Molecular Acoustic Angiography: A New Technique for High-resolution Superharmonic Ultrasound Molecular Imaging.

    PubMed

    Shelton, Sarah E; Lindsey, Brooks D; Tsuruta, James K; Foster, F Stuart; Dayton, Paul A

    2016-03-01

    Ultrasound molecular imaging utilizes targeted microbubbles to bind to vascular targets such as integrins, selectins and other extracellular binding domains. After binding, these microbubbles are typically imaged using low pressures and multi-pulse imaging sequences. In this article, we present an alternative approach for molecular imaging using ultrasound that relies on superharmonic signals produced by microbubble contrast agents. Bound bubbles were insonified near resonance using a low frequency (4 MHz) element and superharmonic echoes were received at high frequencies (25-30 MHz). Although this approach was observed to produce declining image intensity during repeated imaging in both in vitro and in vivo experiments because of bubble destruction, the feasibility of superharmonic molecular imaging was demonstrated for transmit pressures, which are sufficiently high to induce shell disruption in bound microbubbles. This approach was validated using microbubbles targeted to the αvβ3 integrin in a rat fibrosarcoma model (n = 5) and combined with superharmonic images of free microbubbles to produce high-contrast, high-resolution 3-D volumes of both microvascular anatomy and molecular targeting. Image intensity over repeated scans and the effect of microbubble diameter were also assessed in vivo, indicating that larger microbubbles yield increased persistence in image intensity. Using ultrasound-based acoustic angiography images rather than conventional B-mode ultrasound to provide the underlying anatomic information facilitates anatomic localization of molecular markers. Quantitative analysis of relationships between microvasculature and targeting information indicated that most targeting occurred within 50 μm of a resolvable vessel (>100 μm diameter). The combined information provided by these scans may present new opportunities for analyzing relationships between microvascular anatomy and vascular targets, subject only to limitations of the current mechanically scanned system and microbubble persistence to repeated imaging at moderate mechanical indices. PMID:26678155

  10. Normal Values in Healthy Liver in Central India by Acoustic Radiation Force Impulse Imaging

    PubMed Central

    Raghuwanshi, Babita; Jain, Niti; Jain, Manish

    2013-01-01

    Aim: The aim of this study was to reliably measure and define the normal wave velocity values in a healthy liver by Acoustic radiation force impulse imaging (ARFI) technology in central India. Subjects and Methods: Fifty two healthy volunteers underwent acoustic radiation force impulse imaging tissue quantification and were enrolled in this prospective study. All patients were examined clinically by a clinician and blood samples were drawn and tested for liver function test and viral markers for hepatitis B virus, hepatitis C virus. The healthy volunteers were then examined by a certified sonologist and twenty-four measurements per subject were obtained and evaluations were performed. Statistical comparison of all mean data was performed with Students t-test was done. A valueof p < 0.05 was considered significant. A comparative analysis was performed, and interclasscorrelation coefficients were calculated. Results: The sonologist obtained 416 measurements. A statistically significant differencewas found between the mean shear wave velocity values in deep of the right lobe of the liver and the values obtained on the surface of the right lobe (1.2vs1.05 m/s) and between the mean values obtained deep in the right lobe and those obtained deep in the left lobe (1.2vs 1.0 m/s). In almost all cases, the shear wave speeds were between 1 and 2 m/s. Conclusion: Acoustic radiation force impulse imaging quantification of hepatic tissue is more reproducible when applied to the deeper portion of the right lobe of the liver. PMID:24392382

  11. Acoustic Property Reconstruction of a Neonate Yangtze Finless Porpoise's (Neophocaena asiaeorientalis) Head Based on CT Imaging

    PubMed Central

    Wei, Chong; Wang, Zhitao; Song, Zhongchang; Wang, Kexiong; Wang, Ding; Au, Whitlow W. L.; Zhang, Yu

    2015-01-01

    The reconstruction of the acoustic properties of a neonate finless porpoise’s head was performed using X-ray computed tomography (CT). The head of the deceased neonate porpoise was also segmented across the body axis and cut into slices. The averaged sound velocity and density were measured, and the Hounsfield units (HU) of the corresponding slices were obtained from computed tomography scanning. A regression analysis was employed to show the linear relationships between the Hounsfield unit and both sound velocity and density of samples. Furthermore, the CT imaging data were used to compare the HU value, sound velocity, density and acoustic characteristic impedance of the main tissues in the porpoise’s head. The results showed that the linear relationships between HU and both sound velocity and density were qualitatively consistent with previous studies on Indo-pacific humpback dolphins and Cuvier’s beaked whales. However, there was no significant increase of the sound velocity and acoustic impedance from the inner core to the outer layer in this neonate finless porpoise’s melon. PMID:25856588

  12. Acoustic property reconstruction of a neonate Yangtze finless porpoise's (Neophocaena asiaeorientalis) head based on CT imaging.

    PubMed

    Wei, Chong; Wang, Zhitao; Song, Zhongchang; Wang, Kexiong; Wang, Ding; Au, Whitlow W L; Zhang, Yu

    2015-01-01

    The reconstruction of the acoustic properties of a neonate finless porpoise's head was performed using X-ray computed tomography (CT). The head of the deceased neonate porpoise was also segmented across the body axis and cut into slices. The averaged sound velocity and density were measured, and the Hounsfield units (HU) of the corresponding slices were obtained from computed tomography scanning. A regression analysis was employed to show the linear relationships between the Hounsfield unit and both sound velocity and density of samples. Furthermore, the CT imaging data were used to compare the HU value, sound velocity, density and acoustic characteristic impedance of the main tissues in the porpoise's head. The results showed that the linear relationships between HU and both sound velocity and density were qualitatively consistent with previous studies on Indo-pacific humpback dolphins and Cuvier's beaked whales. However, there was no significant increase of the sound velocity and acoustic impedance from the inner core to the outer layer in this neonate finless porpoise's melon. PMID:25856588

  13. Reconstruction of an acoustic pressure field in a resonance tube by particle image velocimetry.

    PubMed

    Kuzuu, K; Hasegawa, S

    2015-11-01

    A technique for estimating an acoustic field in a resonance tube is suggested. The estimation of an acoustic field in a resonance tube is important for the development of the thermoacoustic engine, and can be conducted employing two sensors to measure pressure. While this measurement technique is known as the two-sensor method, care needs to be taken with the location of pressure sensors when conducting pressure measurements. In the present study, particle image velocimetry (PIV) is employed instead of a pressure measurement by a sensor, and two-dimensional velocity vector images are extracted as sequential data from only a one- time recording made by a video camera of PIV. The spatial velocity amplitude is obtained from those images, and a pressure distribution is calculated from velocity amplitudes at two points by extending the equations derived for the two-sensor method. By means of this method, problems relating to the locations and calibrations of multiple pressure sensors are avoided. Furthermore, to verify the accuracy of the present method, the experiments are conducted employing the conventional two-sensor method and laser Doppler velocimetry (LDV). Then, results by the proposed method are compared with those obtained with the two-sensor method and LDV. PMID:26627789

  14. Imaging of Acoustically Coupled Oscillations Due to Flow Past a Shallow Cavity: Effect of Cavity Length Scale

    SciTech Connect

    P. Oshkai; M. Geveci; D. Rockwell; M. Pollack

    2002-12-12

    Flow-acoustic interactions due to fully turbulent inflow past a shallow axisymmetric cavity mounted in a pipe are investigated using a technique of high-image-density particle image velocimetry in conjunction with unsteady pressure measurements. This imaging leads to patterns of velocity, vorticity, streamline topology, and hydrodynamic contributions to the acoustic power integral. Global instantaneous images, as well as time-averaged images, are evaluated to provide insight into the flow physics during tone generation. Emphasis is on the manner in which the streamwise length scale of the cavity alters the major features of the flow structure. These image-based approaches allow identification of regions of the unsteady shear layer that contribute to the instantaneous hydrodynamic component of the acoustic power, which is necessary to maintain a flow tone. In addition, combined image analysis and pressure measurements allow categorization of the instantaneous flow patterns that are associated with types of time traces and spectra of the fluctuating pressure. In contrast to consideration based solely on pressure spectra, it is demonstrated that locked-on tones may actually exhibit intermittent, non-phase-locked images, apparently due to low damping of the acoustic resonator. Locked-on flow tones (without modulation or intermittency), locked-on flow tones with modulation, and non-locked-on oscillations with short-term, highly coherent fluctuations are defined and represented by selected cases. Depending on which of,these regimes occur, the time-averaged Q (quality)-factor and the dimensionless peak pressure are substantially altered.

  15. Investigating the emotional response to room acoustics: A functional magnetic resonance imaging study.

    PubMed

    Lawless, M S; Vigeant, M C

    2015-10-01

    While previous research has demonstrated the powerful influence of pleasant and unpleasant music on emotions, the present study utilizes functional magnetic resonance imaging (fMRI) to assess the positive and negative emotional responses as demonstrated in the brain when listening to music convolved with varying room acoustic conditions. During fMRI scans, subjects rated auralizations created in a simulated concert hall with varying reverberation times. The analysis detected activations in the dorsal striatum, a region associated with anticipation of reward, for two individuals for the highest rated stimulus, though no activations were found for regions associated with negative emotions in any subject. PMID:26520354

  16. In vivo Assessment of Myocardial Stiffness with Acoustic Radiation Force Impulse Imaging

    PubMed Central

    Hsu, Stephen J.; Bouchard, Richard R.; Dumont, Douglas M.; Wolf, Patrick D.; Trahey, Gregg E.

    2007-01-01

    Acoustic radiation force impulse (ARFI) imaging has been demonstrated to be capable of visualizing variations in local stiffness within soft tissue. Recent advances in ARFI beam sequencing and parallel imaging have shortened acquisition times and lessened transducer heating to a point where ARFI acquisitions can be executed at high frame rates on commercially available diagnostic scanners. In vivo ARFI images were acquired with a linear array placed on an exposed canine heart. The electrocardiogram (ECG) was also recorded. When co-registered with the ECG, ARFI displacement images of the heart reflect the expected myocardial stiffness changes during the cardiac cycle. A radiofrequency ablation was performed on the epicardial surface of the left ventricular free wall, creating a small lesion that did not vary in stiffness during a heartbeat, though continued to move with the rest of the heart. ARFI images showed a hemispherical, stiffer region at the ablation site whose displacement magnitude and temporal variation through the cardiac cycle were less than the surrounding untreated myocardium. Sequences with radiation force pulse amplitudes set to zero were acquired to measure potential cardiac motion artifacts within the ARFI images. The results show promise for real-time cardiac ARFI imaging. PMID:17698282

  17. Frame Rate Considerations for Real-Time Abdominal Acoustic Radiation Force Impulse Imaging

    PubMed Central

    Fahey, Brian J.; Palmeri, Mark L.; Trahey, Gregg E.

    2008-01-01

    With the advent of real-time Acoustic Radiation Force Impulse (ARFI) imaging, elevated frame rates are both desirable and relevant from a clinical perspective. However, fundamental limitations on frame rates are imposed by thermal safety concerns related to incident radiation force pulses. Abdominal ARFI imaging utilizes a curvilinear scanning geometry that results in markedly different tissue heating patterns than those previously studied for linear arrays or mechanically-translated concave transducers. Finite Element Method (FEM) models were used to simulate these tissue heating patterns and to analyze the impact of tissue heating on frame rates available for abdominal ARFI imaging. A perfusion model was implemented to account for cooling effects due to blood flow and frame rate limitations were evaluated in the presence of normal, reduced and negligible tissue perfusions. Conventional ARFI acquisition techniques were also compared to ARFI imaging with parallel receive tracking in terms of thermal efficiency. Additionally, thermocouple measurements of transducer face temperature increases were acquired to assess the frame rate limitations imposed by cumulative heating of the imaging array. Frame rates sufficient for many abdominal imaging applications were found to be safely achievable utilizing available ARFI imaging techniques. PMID:17521042

  18. Acoustic Radiation Force Impulse (ARFI) Imaging of Zebrafish Embryo by High-Frequency Coded Excitation Sequence

    PubMed Central

    Park, Jinhyoung; Lee, Jungwoo; Lau, Sien Ting; Lee, Changyang; Huang, Ying; Lien, Ching-Ling; Shung, K. Kirk

    2011-01-01

    Acoustic radiation force impulse (ARFI) imaging has been developed as a non-invasive method for quantitative illustration of tissue stiffness or displacement. Conventional ARFI imaging (210 MHz) has been implemented in commercial scanners for illustrating elastic properties of several organs. The image resolution, however, is too coarse to study mechanical properties of micro-sized objects such as cells. This article thus presents a high-frequency coded excitation ARFI technique, with the ultimate goal of displaying elastic characteristics of cellular structures. Tissue mimicking phantoms and zebrafish embryos are imaged with a 100-MHz lithium niobate (LiNbO3) transducer, by cross-correlating tracked RF echoes with the reference. The phantom results show that the contrast of ARFI image (14 dB) with coded excitation is better than that of the conventional ARFI image (9 dB). The depths of penetration are 2.6 and 2.2 mm, respectively. The stiffness data of the zebrafish demonstrate that the envelope is harder than the embryo region. The temporal displacement change at the embryo and the chorion is as large as 36 and 3.6 ?m. Consequently, this high-frequency ARFI approach may serve as a remote palpation imaging tool that reveals viscoelastic properties of small biological samples. PMID:22101757

  19. Contrast in Intracardiac Acoustic Radiation Force Impulse Images of Radiofrequency Ablation Lesions

    PubMed Central

    Eyerly, Stephanie A.; Bahnson, Tristram D.; Koontz, Jason I.; Bradway, David P.; Dumont, Douglas M.; Trahey, Gregg E.; Wolf, Patrick D.

    2014-01-01

    We have previously shown that intracardiac acoustic radiation force impulse (ARFI) imaging visualizes tissue stiffness changes caused by radiofrequency ablation (RFA). The objectives of this in vivo study were to (1) quantify measured ARFI-induced displacements in RFA lesion and unablated myocardium and (2) calculate the lesion contrast (C) and contrast-to-noise ratio (CNR) in two-dimensional ARFI and conventional intracardiac echo images. In eight canine subjects, an ARFI imaging-electroanatomical mapping system was used to map right atrial ablation lesion sites and guide the acquisition of ARFI images at these sites before and after ablation. Readers of the ARFI images identified lesion sites with high sensitivity (90.2%) and specificity (94.3%) and the average measured ARFI-induced displacements were higher at unablated sites (11.23 1.71 ?m) than at ablated sites (6.06 0.94 ?m). The average lesion C (0.29 0.33) and CNR (1.83 1.75) were significantly higher for ARFI images than for spatially registered conventional B-mode images (C = ?0.03 0.28, CNR = 0.74 0.68). PMID:24554293

  20. Comparison of the Reliability of Acoustic Radiation Force Impulse Imaging and Supersonic Shear Imaging in Measurement of Liver Stiffness.

    PubMed

    Woo, Hyunsik; Lee, Jae Young; Yoon, Jeong Hee; Kim, Won; Cho, Belong; Choi, Byung Ihn

    2015-12-01

    Purpose To compare the reliability of acoustic radiation force impulse (ARFI) imaging and supersonic shear imaging (SSI) in measurement of liver stiffness. Materials and Methods This study was approved by the institutional review board, and written informed consent was obtained for all patients. Seventy-nine patients (25 healthy patients, 26 with Child-Pugh class A, and 28 with Child-Pugh class B or C) were enrolled and analyzed from April 2012 to April 2013. In each patient, three abdominal radiologists performed nine measurements of hepatic shear-wave speed with both ARFI imaging and SSI on the same day. Four weeks later, a second session was performed with the same protocol. Interobserver and intraobserver agreements were calculated by using intraclass correlation coefficients. Technical failures and measurement time were evaluated. Results There were four technical failures in the SSI group and one in the ARFI group (P = .375). The overall interobserver agreement of ARFI imaging was significantly higher than that of SSI (0.941 vs 0.828, P < .001). The overall intraobserver agreement of ARFI imaging was significantly higher than that of SSI (0.915 vs 0.829, P < .001). The overall shear-wave speed measured with SSI was higher than that measured with ARFI imaging (2.04 m/sec 0.88 vs 1.80 m/sec 0.81, P < .001). The measurement time of SSI was longer than that of ARFI imaging (310.8 seconds 88.5 vs 84.5 seconds 15.4, P < .001). Conclusion ARFI imaging was more reliable than SSI in measurement of liver stiffness. The hepatic shear-wave speed measured with SSI was higher than that measured with ARFI imaging, which means that the shear-wave speeds measured with ARFI imaging and SSI cannot be used interchangeably. () RSNA, 2015. PMID:26147680

  1. Evaluation of cervical cancer detection with acoustic radiation force impulse ultrasound imaging

    PubMed Central

    SU, YIJIN; DU, LIANFANG; WU, YING; ZHANG, JUAN; ZHANG, XUEMEI; JIA, XIAO; CAI, YINGYU; LI, YUNHUA; ZHAO, JING; LIU, QIAN

    2013-01-01

    The aim of this study was to evaluate the application of acoustic radiation force impulse (ARFI) ultrasound imaging and its potential value in the characterization of cervical cancer. ARFI ultrasound imaging of the uterine cervix was performed in 58 patients with cervical cancer prior to surgery. The diagnosis of cervical cancer was confirmed by pathological results in each case. eSie Touch elastography imaging (EI), Virtual Touch tissue imaging (VTI) and Virtual Touch tissue quantification (VTQ; Siemens Medical Solutions, Mountain View, CA, USA) were used to qualitatively and quantitatively analyze the elasticity and hardness of lesions. For statistical analysis, the non-parametric Mann-Whitney U test and the Students u test were used to compare the elastic parameters and the results. EI showed that, compared with the surrounding cervical tissue, 72.41% (42 of 58) of the malignant lesions showed 4th or 5th grade images and 27.59% (16 of 58) had 3rd grade images. The EI images showed a significant difference between the malignant lesions and the surrounding normal tissues (P<0.001). VTI showed that compared with the surrounding cervical tissue, 84.48% (49 of 58) of the malignant lesions were stiffer than the surrounding tissues and 15.52% (9 of 58) had black and white honeycomb-like images. The VTI images showed a significant difference between the malignant lesions and normal cervical tissues (P<0.001). The surrounding normal tissues had lower VTQ values, with a mean of 2.111.19 m/sec, while the VTQ values in malignant lesions were higher than the surrounding normal tissues (3.411.59 m/sec, P<0.001). ARFI ultrasound imaging of the uterine cervix may be an objective method for the assessment of soft tissues. It has high sensitivity and specificity in the evaluation of cervical cancer and therefore has good diagnostic value in clinical applications. PMID:23837060

  2. Acoustic radiation force impulse imaging of vulnerable plaques: a finite element method parametric analysis.

    PubMed

    Doherty, Joshua R; Dumont, Douglas M; Trahey, Gregg E; Palmeri, Mark L

    2013-01-01

    Plaque rupture is the most common cause of complications such as stroke and coronary heart failure. Recent histopathological evidence suggests that several plaque features, including a large lipid core and a thin fibrous cap, are associated with plaques most at risk for rupture. Acoustic Radiation Force Impulse (ARFI) imaging, a recently developed ultrasound-based elasticity imaging technique, shows promise for imaging these features noninvasively. Clinically, this could be used to distinguish vulnerable plaques, for which surgical intervention may be required, from those less prone to rupture. In this study, a parametric analysis using Finite Element Method (FEM) models was performed to simulate ARFI imaging of five different carotid artery plaques across a wide range of material properties. It was demonstrated that ARFI imaging could resolve the softer lipid pool from the surrounding, stiffer media and fibrous cap and was most dependent upon the stiffness of the lipid pool component. Stress concentrations due to an ARFI excitation were located in the media and fibrous cap components. In all cases, the maximum Von Mises stress was<1.2 kPa. In comparing these results with others investigating plaque rupture, it is concluded that while the mechanisms may be different, the Von Mises stresses imposed by ARFI imaging are orders of magnitude lower than the stresses associated with blood pressure. PMID:23122224

  3. Stress-Induced Fracturing of Reservoir Rocks: Acoustic Monitoring and μCT Image Analysis

    NASA Astrophysics Data System (ADS)

    Pradhan, Srutarshi; Stroisz, Anna M.; Fjær, Erling; Stenebråten, Jørn F.; Lund, Hans K.; Sønstebø, Eyvind F.

    2015-11-01

    Stress-induced fracturing in reservoir rocks is an important issue for the petroleum industry. While productivity can be enhanced by a controlled fracturing operation, it can trigger borehole instability problems by reactivating existing fractures/faults in a reservoir. However, safe fracturing can improve the quality of operations during CO2 storage, geothermal installation and gas production at and from the reservoir rocks. Therefore, understanding the fracturing behavior of different types of reservoir rocks is a basic need for planning field operations toward these activities. In our study, stress-induced fracturing of rock samples has been monitored by acoustic emission (AE) and post-experiment computer tomography (CT) scans. We have used hollow cylinder cores of sandstones and chalks, which are representatives of reservoir rocks. The fracture-triggering stress has been measured for different rocks and compared with theoretical estimates. The population of AE events shows the location of main fracture arms which is in a good agreement with post-test CT image analysis, and the fracture patterns inside the samples are visualized through 3D image reconstructions. The amplitudes and energies of acoustic events clearly indicate initiation and propagation of the main fractures. Time evolution of the radial strain measured in the fracturing tests will later be compared to model predictions of fracture size.

  4. "Replica-extraction-transfer" nanostructure-initiator mass spectrometry imaging of acoustically printed bacteria.

    PubMed

    Louie, Katherine B; Bowen, Benjamin P; Cheng, Xiaoliang; Berleman, James E; Chakraborty, Romy; Deutschbauer, Adam; Arkin, Adam; Northen, Trent R

    2013-11-19

    Traditionally, microbes are studied under controlled laboratory conditions as isolates in planktonic culture. However, this is a vast extrapolation from their natural state; development of new techniques is required to decipher the largely unknown world of microbial chemical interactions in more realistic environments. The field of mass spectrometry imaging has made significant progress in localizing metabolites in and around bacterial colonies, primarily by using MALDI and ESI-based techniques that interrogate the top surface of the sample. Unfortunately, surface-based laser-desorption techniques, such as nanostructure-initiator mass spectrometry (NIMS), which has advantages in detection of small metabolite compounds and low background, has not been suitable for direct microbe imaging because desorption/ionization occurs on the bottom of the sample. Here, we describe a "replica-extraction-transfer" (REX) technique that overcomes this barrier by transferring biomolecules from agar cultures of spatially arrayed bacterial colonies onto NIMS surfaces; further, we demonstrate that acoustic printing of bacteria can be used to create complex colony geometries to probe microbial interactions with NIMS imaging. REX uses a solvent-laden semisolid (e.g., gel) to first extract metabolites from a microbial sample, such as a biofilm or agar culture; the metabolites are then replica "stamped" onto the NIMS surface. Using analytical standards we show that REX-NIMS effectively transfers and detects a range of small molecule compounds including amino acids and polyamines. This approach is then used to analyze the metabolite composition of streaked Shewanella oneidensis MR1 and Pseudomonas stutzeri RCH2 colonies and further resolve complex patterns produced by acoustic printing of liquid microbial cultures. Applying multivariate statistical analysis of the NIMS imaging data identified ions that were localized to different regions between and within colonies, as well as to the agar gel. Subsequent high-resolution tandem mass spectrometry was used to characterize two species-specific lipids that correlated with the spatial location of each microbial species and were found to be highly abundant in cell extracts. Overall, the use of acoustic printing of bacteria with REX-NIMS imaging will extend the range of analytical capabilities available for characterization of microbial interactions with mass spectrometry. PMID:24111681

  5. A novel imaging technique based on the spatial coherence of backscattered waves: demonstration in the presence of acoustical clutter

    NASA Astrophysics Data System (ADS)

    Dahl, Jeremy J.; Pinton, Gianmarco F.; Lediju, Muyinatu; Trahey, Gregg E.

    2011-03-01

    In the last 20 years, the number of suboptimal and inadequate ultrasound exams has increased. This trend has been linked to the increasing population of overweight and obese individuals. The primary causes of image degradation in these individuals are often attributed to phase aberration and clutter. Phase aberration degrades image quality by distorting the transmitted and received pressure waves, while clutter degrades image quality by introducing incoherent acoustical interference into the received pressure wavefront. Although significant research efforts have pursued the correction of image degradation due to phase aberration, few efforts have characterized or corrected image degradation due to clutter. We have developed a novel imaging technique that is capable of differentiating ultrasonic signals corrupted by acoustical interference. The technique, named short-lag spatial coherence (SLSC) imaging, is based on the spatial coherence of the received ultrasonic wavefront at small spatial distances across the transducer aperture. We demonstrate comparative B-mode and SLSC images using full-wave simulations that include the effects of clutter and show that SLSC imaging generates contrast-to-noise ratios (CNR) and signal-to-noise ratios (SNR) that are significantly better than B-mode imaging under noise-free conditions. In the presence of noise, SLSC imaging significantly outperforms conventional B-mode imaging in all image quality metrics. We demonstrate the use of SLSC imaging in vivo and compare B-mode and SLSC images of human thyroid and liver.

  6. Omega oxidation of 3-hydroxy fatty acids by the human CYP4F gene subfamily enzyme CYP4F11.

    PubMed

    Dhar, Madhurima; Sepkovic, Daniel W; Hirani, Vandana; Magnusson, Ronald P; Lasker, Jerome M

    2008-03-01

    Long-chain 3-hydroxydicarboxylic acids (3-OHDCAs) are thought to arise via beta-oxidation of the corresponding dicarboxylic acids (DCAs), although long-chain DCAs are neither readily transported into nor beta-oxidized in mitochondria. We thus examined whether omega-hydroxylation of 3-hydroxy fatty acids (3-OHFAs), formed via incomplete mitochondrial oxidation, is a more likely pathway for 3-OHDCA production. NADPH-fortified human liver microsomes converted 3-hydroxystearate and 3-hydroxypalmitate to their omega-hydroxylated metabolites, 3,18-dihydroxystearate and 3,16-dihydroxypalmitate, respectively, as identified by GC-MS. Rates of 3,18-dihydroxystearate and 3,16-dihydroxypalmitate formation were 1.23 +/- 0.5 and 1.46 +/- 0.30 nmol product formed/min/mg protein, respectively (mean +/- SD; n = 13). Polyspecific CYP4F antibodies markedly inhibited microsomal omega-hydroxylation of 3-hydroxystearate (68%) and 3-hydroxypalmitate (99%), whereas CYP4A11 and CYP2E1 antibodies had little effect. Upon reconstitution, CYP4F11 and, to a lesser extent, CYP4F2 catalyzed omega-hydroxylation of 3-hydroxystearate, whereas CYP4F3b, CYP4F12, and CYP4A11 exhibited negligible activity. CYP4F11 was the lone CYP4F/A enzyme that effectively oxidized 3-hydroxypalmitate. Kinetic parameters of microsomal 3-hydroxystearate metabolism were K(m) = 55 microM and V(max) = 8.33 min(-1), whereas those for 3-hydroxypalmitate were K(m) = 56.4 microM and V(max) = 14.2 min(-1). CYP4F11 kinetic values resembled those of native microsomes, with K(m) = 53.5 microM and V(max) = 13.9 min(-1) for 3-hydroxystearate and K(m) = 105.8 microM and V(max) = 70.6 min(-1) for 3-hydroxypalmitate. Our data show that 3-hydroxystearate and 3-hydroxypalmitate are converted to omega-hydroxylated 3-OHDCA precursors in human liver and that CYP4F11 is the predominant catalyst of this reaction. CYP4F11-promoted omega-hydroxylation of 3-OHFAs may modulate the disposition of these compounds in pathological states in which enhanced fatty acid mobilization or impairment of mitochondrial fatty acid beta-oxidation increases circulating 3-OHFA levels. PMID:18065749

  7. Acoustic wavefield and Mach wave radiation of flashing arcs in strombolian explosion measured by image luminance

    NASA Astrophysics Data System (ADS)

    Genco, Riccardo; Ripepe, Maurizio; Marchetti, Emanuele; Bonadonna, Costanza; Biass, Sebastien

    2014-10-01

    Explosive activity often generates visible flashing arcs in the volcanic plume considered as the evidence of the shock-front propagation induced by supersonic dynamics. High-speed image processing is used to visualize the pressure wavefield associated with flashing arcs observed in strombolian explosions. Image luminance is converted in virtual acoustic signal compatible with the signal recorded by pressure transducer. Luminance variations are moving with a spherical front at a 344.7 m/s velocity. Flashing arcs travel at the sound speed already 14 m above the vent and are not necessarily the evidence of a supersonic explosive dynamics. However, seconds later, the velocity of small fragments increases, and the spherical acousto-luminance wavefront becomes planar recalling the Mach wave radiation generated by large scale turbulence in high-speed jet. This planar wavefront forms a Mach angle of 55 with the explosive jet axis, suggesting an explosive dynamics moving at Mo = 1.22 Mach number.

  8. Design factors of intravascular dual frequency transducers for super-harmonic contrast imaging and acoustic angiography

    NASA Astrophysics Data System (ADS)

    Ma, Jianguo; Martin, K. Heath; Li, Yang; Dayton, Paul A.; Shung, K. Kirk; Zhou, Qifa; Jiang, Xiaoning

    2015-05-01

    Imaging of coronary vasa vasorum may lead to assessment of the vulnerable plaque development in diagnosis of atherosclerosis diseases. Dual frequency transducers capable of detection of microbubble super-harmonics have shown promise as a new contrast-enhanced intravascular ultrasound (CE-IVUS) platform with the capability of vasa vasorum imaging. Contrast-to-tissue ratio (CTR) in CE-IVUS imaging can be closely associated with low frequency transmitter performance. In this paper, transducer designs encompassing different transducer layouts, transmitting frequencies, and transducer materials are compared for optimization of imaging performance. In the layout selection, the stacked configuration showed superior super-harmonic imaging compared with the interleaved configuration. In the transmitter frequency selection, a decrease in frequency from 6.5 MHz to 5 MHz resulted in an increase of CTR from 15 dB to 22 dB when receiving frequency was kept constant at 30 MHz. In the material selection, the dual frequency transducer with the lead magnesium niobate-lead titanate (PMN-PT) 1-3 composite transmitter yielded higher axial resolution compared to single crystal transmitters (70 μm compared to 150 μm pulse length). These comparisons provide guidelines for the design of intravascular acoustic angiography transducers.

  9. ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS

    SciTech Connect

    Thurman E. Scott, Jr., Ph.D.; Musharraf Zaman, Ph.D.; Younane Abousleiman, Ph.D.

    2001-04-01

    The oil and gas industry has encountered significant problems in the production of oil and gas from weak rocks (such as chalks and limestones) and from unconsolidated sand formations. Problems include subsidence, compaction, sand production, and catastrophic shallow water sand flows during deep water drilling. Together these cost the petroleum industry hundreds of millions of dollars annually. The goals of this first quarterly report is to document the progress on the project to provide data on the acoustic imaging and mechanical properties of soft rock and marine sediments. The project is intended to determine the geophysical (acoustic velocities) rock properties of weak, poorly cemented rocks and unconsolidated sands. In some cases these weak formations can create problems for reservoir engineers. For example, it cost Phillips Petroleum 1 billion dollars to repair of offshore production facilities damaged during the unexpected subsidence and compaction of the Ekofisk Field in the North Sea (Sulak 1991). Another example is the problem of shallow water flows (SWF) occurring in sands just below the seafloor encountered during deep water drilling operations. In these cases the unconsolidated sands uncontrollably flow up around the annulus of the borehole resulting in loss of the drill casing. The $150 million dollar loss of the Ursa development project in the U.S. Gulf Coast resulted from an uncontrolled SWF (Furlow 1998a,b; 1999a,b). The first three tasks outlined in the work plan are: (1) obtain rock samples, (2) construct new acoustic platens, (3) calibrate and test the equipment. These have been completed as scheduled. Rock Mechanics Institute researchers at the University of Oklahoma have obtained eight different types of samples for the experimental program. These include: (a) Danian Chalk, (b) Cordoba Cream Limestone, (c) Indiana Limestone, (d) Ekofisk Chalk, (e) Oil Creek Sandstone, (f) unconsolidated Oil Creek sand, and (g) unconsolidated Brazos river sand. These weak rocks and sands are intended to represent analogs to the formations that present oil and gas engineers with problems during oil and gas production and drilling operations. A series of new axial acoustic sensors have been constructed (and tested) to allow measurement of compressional and shear wave velocities during high pressure triaxial tests on these weak rock and sand samples. In addition, equipment to be utilized over the next 18 months of the project have tested and calibrated. These include the load frames, triaxial pressure cells, pressure sensors, load cells, extensometers, and oscilloscopes have been calibrated and tested. The multichannel acoustic emission and acoustic pulse transmission systems have also been tested. Graduate research assistant, research faculty, and the laboratory technician have begun Tasks 4 and 5 which involve preparing the sand samples and rock samples for testing. The construction of the lateral acoustic sensors has also been started during this quarter as outlined in the project timeline. With the equipment having been tested and calibrated, and the samples now being prepared, the experiments are on schedule to be started in April, 2001.

  10. The standard thermodynamic properties of 4 f metal dichlorides

    NASA Astrophysics Data System (ADS)

    Chervonnyi, A. D.; Chervonnaya, N. A.

    2008-02-01

    The experimental data on heterogeneous and homogeneous equilibria with the participation of 4f metal dichlorides LnCl2 (where Ln = La, …, Lu) were analyzed using the thermodynamic functions of these substances in the gaseous and condensed states described earlier. These data and appearance potential AP(Ln+/LnCl2) measurements were used to calculate the enthalpies of sublimation Δsub H {298/o}. The enthalpies of atomization of these compounds under standard conditions were also calculated. Correlations between the enthalpies of sublimation and crystal lattice structure of 4 f metal trifluorides, trichlorides, and dichlorides are described.

  11. Variable ultrasound trigger delay for improved magnetic resonance acoustic radiation force imaging

    NASA Astrophysics Data System (ADS)

    Mougenot, Charles; Waspe, Adam; Looi, Thomas; Drake, James M.

    2016-01-01

    Magnetic resonance acoustic radiation force imaging (MR-ARFI) allows the quantification of microscopic displacements induced by ultrasound pulses, which are proportional to the local acoustic intensity. This study describes a new method to acquire MR-ARFI maps, which reduces the measurement noise in the quantification of displacement as well as improving its robustness in the presence of motion. Two MR-ARFI sequences were compared in this study. The first sequence ‘variable MSG’ involves switching the polarity of the motion sensitive gradient (MSG) between odd and even image frames. The second sequence named ‘static MSG’ involves a variable ultrasound trigger delay to sonicate during the first or second MSG for odd and even image frames, respectively. As previously published, the data acquired with a variable MSG required the use of reference data acquired prior to any sonication to process displacement maps. In contrary, data acquired with a static MSG were converted to displacement maps without using reference data acquired prior to the sonication. Displacement maps acquired with both sequences were compared by performing sonications for three different conditions: in a polyacrylamide phantom, in the leg muscle of a freely breathing pig and in the leg muscle of pig under apnea. The comparison of images acquired at even image frames and odd image frames indicates that the sequence with a static MSG provides a significantly better steady state (p  <  0.001 based on a Student’s t-test) than the images acquired with a variable MSG. In addition no reference data prior to sonication were required to process displacement maps for data acquired with a static MSG. The absence of reference data prior to sonication provided a 41% reduction of the spatial distribution of noise (p  <  0.001 based on a Student’s t-test) and reduced the sensitivity to motion for displacements acquired with a static MSG. No significant differences were expected and observed for thermal maps acquired with a variable MSG and a static MSG. The use of a static MSG with a variable ultrasound trigger delay improves the ARFI displacement map quality without additional acquisition time and remains compatible with the simultaneous acquisition of MR thermal maps.

  12. Variable ultrasound trigger delay for improved magnetic resonance acoustic radiation force imaging.

    PubMed

    Mougenot, Charles; Waspe, Adam; Looi, Thomas; Drake, James M

    2016-01-21

    Magnetic resonance acoustic radiation force imaging (MR-ARFI) allows the quantification of microscopic displacements induced by ultrasound pulses, which are proportional to the local acoustic intensity. This study describes a new method to acquire MR-ARFI maps, which reduces the measurement noise in the quantification of displacement as well as improving its robustness in the presence of motion. Two MR-ARFI sequences were compared in this study. The first sequence 'variable MSG' involves switching the polarity of the motion sensitive gradient (MSG) between odd and even image frames. The second sequence named 'static MSG' involves a variable ultrasound trigger delay to sonicate during the first or second MSG for odd and even image frames, respectively. As previously published, the data acquired with a variable MSG required the use of reference data acquired prior to any sonication to process displacement maps. In contrary, data acquired with a static MSG were converted to displacement maps without using reference data acquired prior to the sonication. Displacement maps acquired with both sequences were compared by performing sonications for three different conditions: in a polyacrylamide phantom, in the leg muscle of a freely breathing pig and in the leg muscle of pig under apnea. The comparison of images acquired at even image frames and odd image frames indicates that the sequence with a static MSG provides a significantly better steady state (p??images acquired with a variable MSG. In addition no reference data prior to sonication were required to process displacement maps for data acquired with a static MSG. The absence of reference data prior to sonication provided a 41% reduction of the spatial distribution of noise (p??

  13. Evaluation of real-time acoustical holography for breast imaging and biopsy guidance

    NASA Astrophysics Data System (ADS)

    Lehman, Constance D.; Andre, Michael P.; Fecht, Barbara A.; Johansen, Jennifer M.; Shelby, Ronald L.; Shelby, Jerod O.

    1999-05-01

    Ultrasound is an attractive modality for adjunctive characterization of certain breast lesions, but it is not considered specific for cancer and it is not recommended for screening. An imaging technique remarkably different from pulse-echo ultrasound, termed Optical SonographyTM (Advanced Diagnostics, Inc.), uses the through-transmission signal. The method was applied to breast examinations in 41 asymptomatic and symptomatic women ranging in age from 18 to 83 years to evaluate this imaging modality for detection and characterization of breast disease and normal tissue. This approach uses coherent sound and coherent light to produce real-time, large field-of-view images with pronounced edge definition in soft tissues of the body. The system patient interface was modified to improve coupling to the breast and bring the chest wall to within 3 cm of the sound beam. System resolution (full width half maximum of the line-spread function) was 0.5 mm for a swept-frequency beam centered at 2.7 MHz. Resolution degrades slightly in the periphery of the very large 15.2-cm field of view. Dynamic range of the reconstructed 'raw' images (no post processing) was 3000:1. Included in the study population were women with dense parenchyma, palpable ductal carcinoma in situ with negative mammography, superficial and deep fibroadenomas, and calcifications. Successful breast imaging was performed in 40 of 41 women. These images were then compared with images generated using conventional X-ray mammography and pulse-echo ultrasound. Margins of lesions and internal textures were particularly well defined and provided substantial contrast to fatty and dense parenchyma. In two malignant lesions, Optical SonographyTM appeared to approximate more closely tumor extent compared to mammography than pulse-echo sonography. These preliminary studies indicate the method has unique potential for detecting, differentiating, and guiding the biopsy of breast lesions using real-time acoustical holography.

  14. Preliminary study of copper oxide nanoparticles acoustic and magnetic properties for medical imaging

    NASA Astrophysics Data System (ADS)

    Perlman, Or; Weitz, Iris S.; Azhari, Haim

    2015-03-01

    The implementation of multimodal imaging in medicine is highly beneficial as different physical properties may provide complementary information, augmented detection ability, and diagnosis verification. Nanoparticles have been recently used as contrast agents for various imaging modalities. Their significant advantage over conventional large-scale contrast agents is the ability of detection at early stages of the disease, being less prone to obstacles on their path to the target region, and possible conjunction to therapeutics. Copper ions play essential role in human health. They are used as a cofactor for multiple key enzymes involved in various fundamental biochemistry processes. Extremely small size copper oxide nanoparticles (CuO-NPs) are readily soluble in water with high colloidal stability yielding high bioavailability. The goal of this study was to examine the magnetic and acoustic characteristics of CuO-NPs in order to evaluate their potential to serve as contrast imaging agent for both MRI and ultrasound. CuO-NPs 7nm in diameter were synthesized by hot solution method. The particles were scanned using a 9.4T MRI and demonstrated a concentration dependent T1 relaxation time shortening phenomenon. In addition, it was revealed that CuO-NPs can be detected using the ultrasonic B-scan imaging. Finally, speed of sound based ultrasonic computed tomography was applied and showed that CuO-NPs can be clearly imaged. In conclusion, the preliminary results obtained, positively indicate that CuO-NPs may be imaged by both MRI and ultrasound. The results motivate additional in-vivo studies, in which the clinical utility of fused images derived from both modalities for diagnosis improvement will be studied.

  15. Acoustic radiation force impulse imaging of vulnerable plaques: a finite element method parametric analysis

    PubMed Central

    Doherty, Joshua R.; Dumont, Douglas M.; Trahey, Gregg E.; Palmeri, Mark L.

    2012-01-01

    Plaque rupture is the most common cause of complications such as stroke and coronary heart failure. Recent histopathological evidence suggests that several plaque features, including a large lipid core and a thin fibrous cap, are associated with plaques most at risk for rupture. Acoustic Radiation Force Impulse (ARFI) imaging, a recently developed ultrasound-based elasticity imaging technique, shows promise for imaging these features noninvasively. Clinically, this could be used to distinguish vulnerable plaques, for which surgical intervention may be required, from those less prone to rupture. In this study, a parametric analysis using Finite-Element Method (FEM) models was performed to simulate ARFI imaging of five different carotid artery plaques across a wide range of material properties. It was demonstrated that ARFI could resolve the softer lipid pool from the surrounding, stiffer media and fibrous cap and was most dependent upon the stiffness of the lipid pool component. Stress concentrations due to an ARFI excitation were located in the media and fibrous cap components. In all cases, the maximum Von Mises stress was < 1.2 kPa. In comparing these results with others investigating plaque rupture, it is concluded that while the mechanisms may be different, the Von Mises stresses imposed by ARFI are orders of magnitude lower than the stresses associated with blood pressure. PMID:23122224

  16. Full-Wave Iterative Image Reconstruction in Photoacoustic Tomography With Acoustically Inhomogeneous Media

    PubMed Central

    Huang, Chao; Wang, Kun; Nie, Liming; Wang, Lihong V.; Anastasio, Mark A.

    2014-01-01

    Existing approaches to image reconstruction in photoacoustic computed tomography (PACT) with acoustically heterogeneous media are limited to weakly varying media, are computationally burdensome, and/or cannot effectively mitigate the effects of measurement data incompleteness and noise. In this work, we develop and investigate a discrete imaging model for PACT that is based on the exact photoacoustic (PA) wave equation and facilitates the circumvention of these limitations. A key contribution of the work is the establishment of a procedure to implement a matched forward and backprojection operator pair associated with the discrete imaging model, which permits application of a wide-range of modern image reconstruction algorithms that can mitigate the effects of data incompleteness and noise. The forward and backprojection operators are based on the k-space pseudospectral method for computing numerical solutions to the PA wave equation in the time domain. The developed reconstruction methodology is investigated by use of both computer-simulated and experimental PACT measurement data. PMID:23529196

  17. A method for the frequency control in time-resolved two-dimensional gigahertz surface acoustic wave imaging

    SciTech Connect

    Kaneko, Shogo; Tomoda, Motonobu; Matsuda, Osamu

    2014-01-15

    We describe an extension of the time-resolved two-dimensional gigahertz surface acoustic wave imaging based on the optical pump-probe technique with periodic light source at a fixed repetition frequency. Usually such imaging measurement may generate and detect acoustic waves with their frequencies only at or near the integer multiples of the repetition frequency. Here we propose a method which utilizes the amplitude modulation of the excitation pulse train to modify the generation frequency free from the mentioned limitation, and allows for the first time the discrimination of the resulted upper- and lower-side-band frequency components in the detection. The validity of the method is demonstrated in a simple measurement on an isotropic glass plate covered by a metal thin film to extract the dispersion curves of the surface acoustic waves.

  18. Imaging of 3D Ocean Turbulence Microstructure Using Low Frequency Acoustic Waves

    NASA Astrophysics Data System (ADS)

    Minakov, Alexander; Kolyukhin, Dmitriy; Keers, Henk

    2015-04-01

    In the past decade the technique of imaging the ocean structure with low-frequency signal (Hz), produced by air-guns and typically employed during conventional multichannel seismic data acquisition, has emerged. The method is based on extracting and stacking the acoustic energy back-scattered by the ocean temperature and salinity micro- and meso-structure (1 - 100 meters). However, a good understanding of the link between the scattered wavefield utilized by the seismic oceanography and physical processes in the ocean is still lacking. We describe theory and the numerical implementation of a 3D time-dependent stochastic model of ocean turbulence. The velocity and temperature are simulated as homogeneous Gaussian isotropic random fields with the Kolmogorov-Obukhov energy spectrum in the inertial subrange. Numerical modeling technique is employed for sampling of realizations of random fields with a given spatial-temporal spectral tensor. The model used is shown to be representative for a wide range of scales. Using this model, we provide a framework to solve the forward and inverse acoustic scattering problem using marine seismic data. Our full-waveform inversion method is based on the ray-Born approximation which is specifically suitable for the modelling of small velocity perturbations in the ocean. This is illustrated by showing a good match between synthetic seismograms computed using ray-Born and synthetic seismograms produced with a more computationally expensive finite-difference method.

  19. Application of pulse acoustic microscopy technique for 3D imaging bulk microstructure of carbon fiber-reinforced composites.

    PubMed

    Liu, Songping; Guo, Enming; Levin, V M; Liu, Feifei; Petronyuk, Yu S; Zhang, Qianlin

    2006-12-22

    Impulse acoustic microscopy technique is applied for 3D imaging of bulk microstructure of composite materials. Short pulses of focused high-frequency ultrasound have been employed for layer-by-layer imaging of internal microstructure of carbon fiber-reinforced composite (CFRC) laminates. The method provides spatial resolution of 60 microm and in-depth resolution of 80 microm, approximately. Echo signals reflected from structural units--plies, fiber bundles; and microflaws form acoustic images of microstructure at different depth inside samples. The images make it possible to see ply arrays, packing of bundles in plies; binding material distribution over the specimen body. They reveal failure of interply adhesion, buckling of single plies and fiber bundles, internal defoliations and disbonds, voids in the specimen body. The series of successive images offer outstanding possibilities to reconstruct the bulk structure, to estimate local variations of properties, topological and geometrical characteristics of structural components. The imaging technique has been applied to study different types of fiber packing--unidirectional, cross-ply and woven laminates. Mechanisms of ultrasonic contrast for diverse elements in acoustic images of CFRC laminate bulk microstructure and structural defects are discussed. PMID:16876841

  20. High-Resolution Acoustic-Radiation-Force-Impulse Imaging for Assessing Corneal Sclerosis

    PubMed Central

    Shih, Cho-Chiang; Zhou, Qifa; Shung, K. Kirk

    2013-01-01

    In ophthalmology, detecting the biomechanical properties of the cornea can provide valuable information about various corneal pathologies, including keratoconus and the phototoxic effects of ultraviolet radiation on the cornea. Also, the mechanical properties of the cornea can be used to evaluate the recovery from corneal refractive surgeries. Therefore, noninvasive and high-resolution estimation of the stiffness distribution in the cornea is important in ophthalmic diagnosis. The present study established a method for high-resolution acoustic-radiation-force-impulse (ARFI) imaging based on a dual-frequency confocal transducer in order to obtain a relative stiffness map, which was used to assess corneal sclerosis. An 11-MHz pushing element was used to induce localized displacements of tissue, which were monitored by a 48-MHz imaging element. Since the tissue displacements are directly correlated with the tissue elastic properties, the stiffness distribution in a tiny region of the cornea can be found by a mechanical B/D scan. The experimental system was verified using tissue-mimicking phantoms that included different geometric structures. Ex vivo cornea experiments were carried out using fresh porcine eyeballs. Corneas with localized sclerosis were created artificially by the injection of a formalin solution. The phantom experiments showed that the distributions of stiffness within different phantoms can be recognized clearly using ARFI imaging, and the measured lateral and axial resolutions of this imaging system were 177 and 153 ?m, respectively. The ex vivo experimental results from ARFI imaging showed that a tiny region of localized sclerosis in the cornea could be distinguished. All of the obtained results demonstrate that high-resolution ARFI imaging has considerable potential for the clinical diagnosis of corneal sclerosis. PMID:23584258

  1. Acoustic attenuation compensation in photoacoustic tomography: application to high-resolution 3D imaging of vascular networks in mice

    NASA Astrophysics Data System (ADS)

    Treeby, Bradley E.; Laufer, Jan G.; Zhang, Edward Z.; Norris, Francesca C.; Lythgoe, Mark F.; Beard, Paul C.; Cox, B. T.

    2011-03-01

    The reconstruction algorithms commonly used in photoacoustic tomography do not account for the effects of acoustic attenuation on the measured time-domain signals. For experimental measurements made in biological tissue, acoustic attenuation causes the high frequency components of the generated ultrasound signals to be significantly reduced. When this signal loss is neglected, it manifests as a depth dependent magnitude error and blurring of features within the reconstructed photoacoustic image. Here, the approach described by Treeby et al. [Inverse Problems 26(11), p. 115003, 2010] is applied to the reconstruction of high-resolution threedimensional photoacoustic images of vascular networks around the abdomen of a pregnant female mouse. The reconstruction is based on the idea of time reversal in which a numerical model of the acoustic forward problem is run backwards in time. Compensation of acoustic attenuation in the inverse problem is achieved by using a forward model that accurately accounts for the frequency dependent attenuation experimentally observed in biological tissue. The regularisation of the inverse problem is discussed, and the methodology demonstrated through the reconstruction of several images. Clear improvements in image magnitude and resolution are seen when attenuation compensation is included.

  2. Design and Numerical Evaluation of Off-Axis Aplanatic Straubel Mirror for Underwater Acoustic Imaging

    NASA Astrophysics Data System (ADS)

    Sato, Yuji; Mizutani, Koichi; Wakatsuki, Naoto; Nakamura, Toshiaki

    2012-07-01

    An aplanatic Straubel mirror was designed for underwater acoustic imaging. However, there was a problem in that incident sound waves coming into the aplanatic Straubel mirror were interrupted by a receiver array placed in front of the mirror. An off-axis Straubel mirror is proposed to solve this problem. In this study, an off-axis aplanatic Straubel mirror is designed and evaluated using numerical calculation to verify the feasibility of the off-axis design. Upon comparison of the off-axis and ordinary aplanatic Straubel mirrors, the off-axis mirror shows almost the same convergence property as the ordinary one when a receiver array exists. The off-axis aplanatic Straubel mirror is compared with an aplanatic Fresnel lens because this lens is not affected by the receiver. The results show that the off-axis mirror showed a smaller aberration than the aplanatic Fresnel lens at a wider angle of view.

  3. Acoustical cross-talk in row-column addressed 2-D transducer arrays for ultrasound imaging.

    PubMed

    Christiansen, Thomas Lehrmann; Jensen, Jrgen Arendt; Thomsen, Erik Vilain

    2015-12-01

    The acoustical cross-talk in row-column addressed 2-D transducer arrays for volumetric ultrasound imaging is investigated. Experimental results from a 2.7 MHz, ?/2-pitch capacitive micromachined ultrasonic transducer (CMUT) array with 62 rows and 62 columns are presented and analyzed in the frequency-wavenumber domain. The sources of cross-talk are identified and predicted theoretically. The nearest neighbor cross-talk is -23.93.7 dB when the array is used as a 1-D array with the rows functioning as both transmitters and receivers. In the row-column configuration, with the columns transmitting and the rows receiving, the cross-talk is reduced to -40.23.5 dB. PMID:26216122

  4. Acoustic characterization of ultrasound contrast microbubbles and echogenic liposomes: Applications to imaging and drug-delivery

    NASA Astrophysics Data System (ADS)

    Paul, Shirshendu

    Micron- to nanometer - sized ultrasound agents, like encapsulated microbubbles and echogenic liposomes (ELIPs), are being actively developed for possible clinical implementations in diagnostic imaging and ultrasound mediated drug/gene delivery. The primary objective of this thesis is to characterize the acoustic behavior of and the ultrasound-mediated contents release from these contrast agents for developing multi-functional ultrasound contrast agents. Subharmonic imaging using contrast microbubbles can improve image quality by providing a higher signal to noise ratio. However, the design and development of contrast microbubbles with favorable subharmonic behavior requires accurate mathematical models capable of predicting their nonlinear dynamics. To this goal, 'strain-softening' viscoelastic interfacial models of the encapsulation were developed and subsequently utilized to simulate the dynamics of encapsulated microbubbles. A hierarchical two-pronged approach of modeling --- a model is applied to one set of experimental data to obtain the model parameters (material characterization), and then the model is validated against a second independent experiment --- is demonstrated in this thesis for two lipid coated (SonazoidRTM and DefinityRTM) and a few polymer (polylactide) encapsulated microbubbles. The proposed models were successful in predicting several experimentally observed behaviors e.g., low subharmonic thresholds and "compression-only" radial oscillations. Results indicate that neglecting the polydisperse size distribution of contrast agent suspensions, a common practice in the literature, can lead to inaccurate results. In vitro experimental investigation of the dependence of subharmonic response from these microbubbles on the ambient pressure is also in conformity with the recent numerical investigations, showing both increase or decrease under appropriate excitation conditions. Experimental characterization of the ELIPs and polymersomes was performed with the goal of demonstrating their potential as ultrasound agents with simultaneous imaging and drug/gene delivery applications --- 'dual-purpose' contrast agents. Both in vitro acoustic studies and ultrasound imaging (performed in NDSU by our collaborators) showed the echogenicity of the various formulations studied. We believe that this echogenicity results from the larger diameter liposomes present in the polydisperse suspension obtained after reconstitution of the lyophilized powders. Although, ultrasound excitation (< 5 MHz) alone was incapable of causing optimal release of contents, a dual-triggering strategy (with enzymes or redox) proved successful, resulting in a total release of up to 80-90%. Considering these experimental results, it can be concluded that these novel formulations hold the potential of providing powerful treatment strategies for many diseases, including cardiovascular ones and various cancers.

  5. A Spinal Cord Window Chamber Model for In Vivo Longitudinal Multimodal Optical and Acoustic Imaging in a Murine Model

    PubMed Central

    Maeda, Azusa; Conroy, Leigh; McMullen, Jesse D.; Silver, Jason I.; Stapleton, Shawn; Vitkin, Alex; Lindsay, Patricia; Burrell, Kelly; Zadeh, Gelareh; Fehlings, Michael G.; DaCosta, Ralph S.

    2013-01-01

    In vivo and direct imaging of the murine spinal cord and its vasculature using multimodal (optical and acoustic) imaging techniques could significantly advance preclinical studies of the spinal cord. Such intrinsically high resolution and complementary imaging technologies could provide a powerful means of quantitatively monitoring changes in anatomy, structure, physiology and function of the living cord over time after traumatic injury, onset of disease, or therapeutic intervention. However, longitudinal in vivo imaging of the intact spinal cord in rodent models has been challenging, requiring repeated surgeries to expose the cord for imaging or sacrifice of animals at various time points for ex vivo tissue analysis. To address these limitations, we have developed an implantable spinal cord window chamber (SCWC) device and procedures in mice for repeated multimodal intravital microscopic imaging of the cord and its vasculature in situ. We present methodology for using our SCWC to achieve spatially co-registered optical-acoustic imaging performed serially for up to four weeks, without damaging the cord or induction of locomotor deficits in implanted animals. To demonstrate the feasibility, we used the SCWC model to study the response of the normal spinal cord vasculature to ionizing radiation over time using white light and fluorescence microscopy combined with optical coherence tomography (OCT) in vivo. In vivo power Doppler ultrasound and photoacoustics were used to directly visualize the cord and vascular structures and to measure hemoglobin oxygen saturation through the complete spinal cord, respectively. The model was also used for intravital imaging of spinal micrometastases resulting from primary brain tumor using fluorescence and bioluminescence imaging. Our SCWC model overcomes previous in vivo imaging challenges, and our data provide evidence of the broader utility of hybridized optical-acoustic imaging methods for obtaining multiparametric and rich imaging data sets, including over extended periods, for preclinical in vivo spinal cord research. PMID:23516432

  6. Imaging of Acoustically Coupled Oscillations Due to Flow Past a Shallow Cavity: Effect of Cavity Length Scale

    SciTech Connect

    P Oshkai; M Geveci; D Rockwell; M Pollack

    2004-05-24

    Flow-acoustic interactions due to fully turbulent inflow past a shallow axisymmetric cavity mounted in a pipe, which give rise to flow tones, are investigated using a technique of high-image-density particle image velocimetry in conjunction with unsteady pressure measurements. This imaging leads to patterns of velocity, vorticity, streamline topology, and hydrodynamic contributions to the acoustic power integral. Global instantaneous images, as well as time-averaged images, are evaluated to provide insight into the flow physics during tone generation. Emphasis is on the manner in which the streamwise length scale of the cavity alters the major features of the flow structure. These image-based approaches allow identification of regions of the unsteady shear layer that contribute to the instantaneous hydrodynamic component of the acoustic power, which is necessary to maintain a flow tone. In addition, combined image analysis and pressure measurements allow categorization of the instantaneous flow patterns that are associated with types of time traces and spectra of the fluctuating pressure. In contrast to consideration based solely on pressure spectra, it is demonstrated that locked-on tones may actually exhibit intermittent, non-phase-locked images, apparently due to low damping of the acoustic resonator. Locked-on flow tones (without modulation or intermittency), locked-on flow tones with modulation, and non-locked-on oscillations with short-term, highly coherent fluctuations are defined and represented by selected cases. Depending on which of these regimes occur, the time-averaged Q (quality)-factor and the dimensionless peak pressure are substantially altered.

  7. In Vivo Study of Transverse Carpal Ligament Stiffness Using Acoustic Radiation Force Impulse (ARFI) Imaging

    PubMed Central

    Shen, Zhilei Liu; Vince, D. Geoffrey; Li, Zong-Ming

    2013-01-01

    The transverse carpal ligament (TCL) forms the volar boundary of the carpal tunnel and may provide mechanical constraint to the median nerve, leading to carpal tunnel syndrome. Therefore, the mechanical properties of the TCL are essential to better understand the etiology of carpal tunnel syndrome. The purpose of this study was to investigate the in vivo TCL stiffness using acoustic radiation force impulse (ARFI) imaging. The shear wave velocity (SWV) of the TCL was measured using Virtual Touch IQTM software in 15 healthy, male subjects. The skin and the thenar muscles were also examined as reference tissues. In addition, the effects of measurement location and ultrasound transducer compression on the SWV were studied. The SWV of the TCL was dependent on the tissue location, with greater SWV values within the muscle-attached region than those outside of the muscle-attached region. The SWV of the TCL was significantly smaller without compression (5.21 1.08 m/s) than with compression (6.62 1.18 m/s). The SWV measurements of the skin and the thenar muscles were also affected by transducer compression, but to different extents than the SWV of the TCL. Therefore to standardize the ARFI imaging procedure, it is recommended that a layer of ultrasound gel be maintained to minimize the effects of tissue compression. This study demonstrated the feasibility of ARFI imaging for assessing the stiffness characteristics of the TCL in vivo, which has the potential to identify pathomechanical changes of the tissue. PMID:23861919

  8. SIMULTANEOUS BILATERAL REAL-TIME 3-D TRANSCRANIAL ULTRASOUND IMAGING AT 1 MHZ THROUGH POOR ACOUSTIC WINDOWS

    PubMed Central

    Lindsey, Brooks D.; Nicoletto, Heather A.; Bennett, Ellen R.; Laskowitz, Daniel T.; Smith, Stephen W.

    2013-01-01

    Ultrasound imaging has been proposed as a rapid, portable alternative imaging modality to examine stroke patients in pre-hospital or emergency room settings. However, in performing transcranial ultrasound examinations, 8%–29% of patients in a general population may present with window failure, in which case it is not possible to acquire clinically useful sonographic information through the temporal bone acoustic window. In this work, we describe the technical considerations, design and fabrication of low-frequency (1.2 MHz), large aperture (25.3 mm) sparse matrix array transducers for 3-D imaging in the event of window failure. These transducers are integrated into a system for real-time 3-D bilateral transcranial imaging—the ultrasound brain helmet—and color flow imaging capabilities at 1.2 MHz are directly compared with arrays operating at 1.8 MHz in a flow phantom with attenuation comparable to the in vivo case. Contrast-enhanced imaging allowed visualization of arteries of the Circle of Willis in 5 of 5 subjects and 8 of 10 sides of the head despite probe placement outside of the acoustic window. Results suggest that this type of transducer may allow acquisition of useful images either in individuals with poor windows or outside of the temporal acoustic window in the field. PMID:23415287

  9. Nonlinear refraction measurements in presence of nonlinear absorption using phase object in a 4f system

    NASA Astrophysics Data System (ADS)

    Boudebs, G.; Cherukulappurath, S.

    2005-06-01

    We report a technique to measure the value of the nonlinear refractive index of materials in presence of nonlinear absorption using a phase object at the entry of a 4f coherent imaging system. We show that it is possible to obtain a signal approximately due only to the induced nonlinear refraction in presence of two photon absorption. Experimental and simulated Z-scan transmittance profiles with and without phase object, as well as acquired and calculated images are presented here in order to validate our approach. We show also that the use of a reference material simplifies the measurement procedure avoiding computer fits.

  10. Heterometallic 3d-4f single-molecule magnets.

    PubMed

    Rosado Piquer, Lidia; Saudo, E Carolina

    2015-05-21

    The promising potential applications, such as information processing and storage or molecular spintronics, of single-molecule magnets (SMMs) have spurred on the research of new, better SMMs. In this context, lanthanide ions have been seen as ideal candidates for new heterometallic transition metal-lanthanide SMMs. This perspective reviews 3d-4f SMMs up to 2014 and highlights the most significant advances and challenges of the field. PMID:25847327

  11. An electrochemical and high-speed imaging study of micropore decontamination by acoustic bubble entrapment.

    PubMed

    Offin, Douglas G; Birkin, Peter R; Leighton, Timothy G

    2014-03-14

    Electrochemical and high-speed imaging techniques are used to study the abilities of ultrasonically-activated bubbles to clean out micropores. Cylindrical pores with dimensions (diameter × depth) of 500 μm × 400 μm (aspect ratio 0.8), 125 μm × 350 μm (aspect ratio 2.8) and 50 μm × 200 μm (aspect ratio 4.0) are fabricated in glass substrates. Each pore is contaminated by filling it with an electrochemically inactive blocking organic material (thickened methyl salicylate) before the substrate is placed in a solution containing an electroactive species (Fe(CN)6(3-)). An electrode is fabricated at the base of each pore and the Faradaic current is used to monitor the decontamination as a function of time. For the largest pore, decontamination driven by ultrasound (generated by a horn type transducer) and bulk fluid flow are compared. It is shown that ultrasound is much more effective than flow alone, and that bulk fluid flow at the rates used cannot decontaminate the pore completely, but that ultrasound can. In the case of the 125 μm pore, high-speed imaging is used to elucidate the cleaning mechanisms involved in ultrasonic decontamination and reveals that acoustic bubble entrapment is a key feature. The smallest pore is used to explore the limits of decontamination and it is found that ultrasound is still effective at this size under the conditions employed. PMID:24477554

  12. Inferences of Particle Size and Composition From Video-like Images Based on Acoustic Data: Grotto Plume, Main Endeavor Field

    NASA Astrophysics Data System (ADS)

    Bemis, K. G.; Rona, P. A.; Santilli, K.; Dastur, J.; Silver, D.

    2004-12-01

    Optical and acoustic scattering from particles in a seafloor hydrothermal plume can be related if the particle properties and scattering mechanisms are known. We assume Rayleigh backscattering of sound and Mie forward scattering of light. We then use the particle concentrations implicit in the observed acoustic backscatter intensity to recreate the optical image a camera would see given a particular lighting level. The motivation for this study is to discover what information on particle size and composition in the buoyant plume can be inferred from a comparison of the calculated optical images (based on acoustic data) with actual video images from the acoustic acquisition cruise and the IMAX film "Volcanoes of the Deep Sea" (Stephen Low Productions, Inc.). Because the geologists, biologists and oceanographers involved in the study of seafloor hydrothermal plumes all "see" plumes in different ways, an additional motivation is to create more realistic plume images from the acoustic data. By using visualization techniques, with realistic lighting models, we can convert the plume image from mechanical waves (sound) to electromagnetic waves (light). The resulting image depends on assumptions about the particle size distribution and composition. Conversion of the volume scattering coefficients from Rayleigh to Mie scattering is accomplished by an extinction scale factor that depends on the wavelengths of light and sound and on the average particle size. We also make an adjustment to the scattered light based on the particles reflectivity (albedo) and color. We present a series of images of acoustic data for Grotto Plume, Main Endeavour Field (within the Endeavour ISS Site) using both realistic lighting models and traditional visualization techniques to investigate the dependence of the images on assumptions about particle composition and size. Sensitivity analysis suggests that the visibility of the buoyant plume increases as the intensity of supplied light increases, the particle size decreases, and the particle reflectivity increases. However, decreasing the particle size (and thus increasing the extinction scale factor) results in a wider, less defined plume and increases the relative importance of the acoustic background noise; the best fit of our calculated optical images to the character of actual video images of the bottom few meters of the plumes (the acoustic data volume is 55 m tall) suggests that average particle size is fairly large ( 1000 ? m) in the buoyant plume. This suggests that existing data on particle size distributions underestimates the average particle size; the best explanation is the breakup of aggregates of particles during collection and filtering of water samples (no in situ measurements exist). We also investigate the effects of particle color on plume color by using models based on data collected by Feely et al (1987), Walker and Baker (1988), and Mottl and McConachy (1990). Highly reflective particles result in result in sharper-edged plumes suggesting that pyrite (albedo 0.6) and chalcopyrite (albedo 0.3) are the dominant particle compositions. This study shows that plume particles in the buoyant plume are probably larger than previously suspected and a predominance of pyrite and chalcopyrite is necessary to explain the high reflectance of black smoker plumes.

  13. Measurement of acoustic noise effect due to the gradient pulsing in functional magnetic resonance imaging (fMRI)

    NASA Astrophysics Data System (ADS)

    Chung, SungTaek; Song, Inchang; Park, Hyun Wook

    1999-05-01

    In MRI, gradient magnetic fields are used to obtain the spatial information by frequency modulation of the received signal. The gradient fields are generated by switching currents on the gradient coils, which generates acoustic noise due to Lorentzian force. In particular, fast imaging methods, which are usually used for fMRI, require fast switching of the gradient pulse, thereby generating large acoustic noise. The intensity of the acoustic noise depends on the imaging method and the pulse sequences. The acoustic noise induced by gradient pulsing may interfere for signal enhancement of brain areas with the presentation of auditory stimuli during fMRI. In this paper, the gradient pulsing effects on fMRI are analyzed for different combinations of gradients. The experimental results show that total activations by visual stimulation are slightly larger for a combination of Z readout and Y phase-encoding gradients than those for a combination of Y readout and Z phase-encoding gradients when sagittal-view fMRI is performed.

  14. Imaging electrical impedance from acoustic measurements by means of magnetoacoustic tomography with magnetic induction (MAT-MI).

    PubMed

    Li, Xu; Xu, Yuan; He, Bin

    2007-02-01

    We have conducted computer simulation and experimental studies on magnetoacoustic-tomography with magnetic induction (MAT-MI) for electrical impedance imaging. In MAT-MI, the object to be imaged is placed in a static magnetic field, while pulsed magnetic stimulation is applied in order to induce eddy current in the object. In the static magnetic field, the Lorentz force acts upon the eddy current and causes acoustic vibrations in the object. The propagated acoustic wave is then measured around the object to reconstruct the electrical impedance distribution. In the present simulation study, a two-layer spherical model is used. Parameters of the model such as sample size, conductivity values, strength of the static and pulsed magnetic field, are set to simulate features of biological tissue samples and feasible experimental constraints. In the forward simulation, the electrical potential and current density are solved using Poisson's equation, and the acoustic pressure is calculated as the forward solution. The electrical impedance distribution is then reconstructed from the simulated pressure distribution surrounding the sample. The present computer simulation results suggest that MAT-MI can reconstruct conductivity images of biological tissue with high spatial resolution and high contrast. The feasibility of MAT-MI in providing high spatial resolution images containing impedance-related information has also been demonstrated in a phantom experiment. PMID:17278589

  15. High resolution imaging beyond the acoustic diffraction limit in deep tissue via ultrasound-switchable NIR fluorescence

    PubMed Central

    Pei, Yanbo; Wei, Ming-Yuan; Cheng, Bingbing; Liu, Yuan; Xie, Zhiwei; Nguyen, Kytai; Yuan, Baohong

    2014-01-01

    Fluorescence imaging in deep tissue with high spatial resolution is highly desirable because it can provide details about tissue's structural, functional, and molecular information. Unfortunately, current fluorescence imaging techniques are limited either in penetration depth (microscopy) or spatial resolution (diffuse light based imaging) as a result of strong light scattering in deep tissue. To overcome this limitation, we developed an ultrasound-switchable fluorescence (USF) imaging technique whereby ultrasound was used to switch on/off the emission of near infrared (NIR) fluorophores. We synthesized and characterized unique NIR USF contrast agents. The excellent switching properties of these agents, combined with the sensitive USF imaging system developed in this study, enabled us to image fluorescent targets in deep tissue with spatial resolution beyond the acoustic diffraction limit. PMID:24732947

  16. Quantitative enhancement of fatigue crack monitoring by imaging surface acoustic wave reflection in a space-cycle-load domain

    SciTech Connect

    Connolly, G. D.; Rokhlin, S. I.

    2011-06-23

    The surface wave acoustic method is applied to the in-situ monitoring of fatigue crack initiation and evolution on tension specimens. A small low-frequency periodic loading is also applied, resulting in a nonlinear modulation of reflected pulses. The acoustic wave reflections are collected for: each experimental cycle; a range of applied tension and modulation load levels; and a range of spatial propagation positions, and are presented in image form to aid pattern identification. Salient features of the image are then extracted and processed to evaluate the initiation time of the crack and its subsequent size evolution until sample failure. Additionally, a method for enhancing signal to noise ratio in Ti-6242 alloy samples is demonstrated.

  17. Non-intrusive, high-resolution, real-time, two-dimensional imaging of multiphase materials using acoustic array sensors

    SciTech Connect

    Cassiède, M.; Shaw, J. M.

    2015-04-15

    Two parallel multi-element ultrasonic acoustic arrays combined with sets of focal laws for acoustic signal generation and a classical tomographic inversion algorithm are used to generate real-time two-dimensional micro seismic acoustic images of multiphase materials. Proof of concept and calibration measurements were performed for single phase and two phase liquids, uniform polyvinyl chloride (PVC) plates, and aluminum cylinders imbedded in PVC plates. Measurement artefacts, arising from the limited range of viewing angles, and the compromise between data acquisition rate and image quality are discussed. The angle range of scanning and the image resolution were varied, and the effects on the quality of the reproduction of the speed of sound profiles of model solids and liquids with known geometries and compositions were analysed in detail. The best image quality results were obtained for a scanning angle range of [−35°, 35°] at a step size of 2.5° post processed to generate images on a 40 μm square grid. The data acquisition time for high quality images with a 30 mm × 40 mm view field is 10 min. Representation of two-phase solids with large differences in speed of sound between phases and where one phase is dispersed in the form of macroscopic objects (greater than 1 mm in diameter) proved to be the most difficult to image accurately. Liquid-liquid and liquid-vapor phase boundaries, in micro porous solids by contrast, were more readily defined. Displacement of air by water and water by heptane in natural porous limestone provides illustrative kinetic examples. Measurement results with these realistic cases demonstrate the feasibility of the technique to monitor in real time and on the micrometer length scale local composition and flow of organic liquids in inorganic porous media, one of many envisioned engineering applications. Improvement of data acquisition rate is an area for future collaborative study.

  18. Non-intrusive, high-resolution, real-time, two-dimensional imaging of multiphase materials using acoustic array sensors

    NASA Astrophysics Data System (ADS)

    Cassiède, M.; Shaw, J. M.

    2015-04-01

    Two parallel multi-element ultrasonic acoustic arrays combined with sets of focal laws for acoustic signal generation and a classical tomographic inversion algorithm are used to generate real-time two-dimensional micro seismic acoustic images of multiphase materials. Proof of concept and calibration measurements were performed for single phase and two phase liquids, uniform polyvinyl chloride (PVC) plates, and aluminum cylinders imbedded in PVC plates. Measurement artefacts, arising from the limited range of viewing angles, and the compromise between data acquisition rate and image quality are discussed. The angle range of scanning and the image resolution were varied, and the effects on the quality of the reproduction of the speed of sound profiles of model solids and liquids with known geometries and compositions were analysed in detail. The best image quality results were obtained for a scanning angle range of [-35°, 35°] at a step size of 2.5° post processed to generate images on a 40 μm square grid. The data acquisition time for high quality images with a 30 mm × 40 mm view field is 10 min. Representation of two-phase solids with large differences in speed of sound between phases and where one phase is dispersed in the form of macroscopic objects (greater than 1 mm in diameter) proved to be the most difficult to image accurately. Liquid-liquid and liquid-vapor phase boundaries, in micro porous solids by contrast, were more readily defined. Displacement of air by water and water by heptane in natural porous limestone provides illustrative kinetic examples. Measurement results with these realistic cases demonstrate the feasibility of the technique to monitor in real time and on the micrometer length scale local composition and flow of organic liquids in inorganic porous media, one of many envisioned engineering applications. Improvement of data acquisition rate is an area for future collaborative study.

  19. Non-intrusive, high-resolution, real-time, two-dimensional imaging of multiphase materials using acoustic array sensors.

    PubMed

    Cassiède, M; Shaw, J M

    2015-04-01

    Two parallel multi-element ultrasonic acoustic arrays combined with sets of focal laws for acoustic signal generation and a classical tomographic inversion algorithm are used to generate real-time two-dimensional micro seismic acoustic images of multiphase materials. Proof of concept and calibration measurements were performed for single phase and two phase liquids, uniform polyvinyl chloride (PVC) plates, and aluminum cylinders imbedded in PVC plates. Measurement artefacts, arising from the limited range of viewing angles, and the compromise between data acquisition rate and image quality are discussed. The angle range of scanning and the image resolution were varied, and the effects on the quality of the reproduction of the speed of sound profiles of model solids and liquids with known geometries and compositions were analysed in detail. The best image quality results were obtained for a scanning angle range of [-35°, 35°] at a step size of 2.5° post processed to generate images on a 40 μm square grid. The data acquisition time for high quality images with a 30 mm × 40 mm view field is 10 min. Representation of two-phase solids with large differences in speed of sound between phases and where one phase is dispersed in the form of macroscopic objects (greater than 1 mm in diameter) proved to be the most difficult to image accurately. Liquid-liquid and liquid-vapor phase boundaries, in micro porous solids by contrast, were more readily defined. Displacement of air by water and water by heptane in natural porous limestone provides illustrative kinetic examples. Measurement results with these realistic cases demonstrate the feasibility of the technique to monitor in real time and on the micrometer length scale local composition and flow of organic liquids in inorganic porous media, one of many envisioned engineering applications. Improvement of data acquisition rate is an area for future collaborative study. PMID:25933884

  20. Keyhole acceleration for magnetic resonance acoustic radiation force imaging (MR ARFI).

    PubMed

    Paquin, Raphal; Vignaud, Alexandre; Marsac, Laurent; Younan, Youliana; Lehricy, Stphane; Tanter, Mickal; Aubry, Jean-Franois

    2013-12-01

    MR ARFI measures the displacement induced by the ultrasonic radiation force and provides the location of the focal spot without significant heating effects. Displacements maps obtained with MR ARFI provide an indirect estimation of the acoustic beam intensity at the target. This measure is essential for dose estimation prior to focused ultrasound treatments (FUS) and adaptive focusing procedures of MR-guided transcranial and transribs FUS. In the latter case, the beam correction is achieved by maximizing the displacement at focus. A significant number of serial MR ARFI images are required and thus, a partial k-space updating method, such as keyhole appears as a method of choice. The purpose of this work is to demonstrate via simulations and experiments the efficiency of the keyhole technique combined with a two-dimensional spin-echo MR ARFI pulse sequence. The method was implemented in an ex vivo calf brain taking advantage of the a priori knowledge of the focal spot profile. The coincidence of the phase-encoding axis with the longest axis of the focal spot makes the best use of the technique. Our approach rapidly provides the focal spot localization with accuracy, and with a substantial increase to the signal-to-noise ratio, while reducing ultrasound energy needed during MR-guided adaptive focusing procedures. PMID:24079934

  1. A simulation technique for 3D MR-guided acoustic radiation force imaging

    SciTech Connect

    Payne, Allison; Bever, Josh de; Farrer, Alexis; Coats, Brittany; Parker, Dennis L.; Christensen, Douglas A.

    2015-02-15

    Purpose: In magnetic resonance-guided focused ultrasound (MRgFUS) therapies, the in situ characterization of the focal spot location and quality is critical. MR acoustic radiation force imaging (MR-ARFI) is a technique that measures the tissue displacement caused by the radiation force exerted by the ultrasound beam. This work presents a new technique to model the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model. Methods: When a steady-state point-source force acts internally in an infinite homogeneous medium, the displacement of the material in all directions is given by the Somigliana elastostatic tensor. The radiation force field, which is caused by absorption and reflection of the incident ultrasound intensity pattern, will be spatially distributed, and the tensor formulation takes the form of a convolution of a 3D Green’s function with the force field. The dynamic accumulation of MR phase during the ultrasound pulse can be theoretically accounted for through a time-of-arrival weighting of the Green’s function. This theoretical model was evaluated experimentally in gelatin phantoms of varied stiffness (125-, 175-, and 250-bloom). The acoustic and mechanical properties of the phantoms used as parameters of the model were measured using independent techniques. Displacements at focal depths of 30- and 45-mm in the phantoms were measured by a 3D spin echo MR-ARFI segmented-EPI sequence. Results: The simulated displacements agreed with the MR-ARFI measured displacements for all bloom values and focal depths with a normalized RMS difference of 0.055 (range 0.028–0.12). The displacement magnitude decreased and the displacement pattern broadened with increased bloom value for both focal depths, as predicted by the theory. Conclusions: A new technique that models the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model theory has been rigorously validated through comparison with experimentally obtained 3D displacement data in homogeneous gelatin phantoms using a 3D MR-ARFI sequence. The agreement of the experimentally measured and simulated results demonstrates the potential to use MR-ARFI displacement data in MRgFUS therapies.

  2. A simulation technique for 3D MR-guided acoustic radiation force imaging

    PubMed Central

    Payne, Allison; de Bever, Josh; Farrer, Alexis; Coats, Brittany; Parker, Dennis L.; Christensen, Douglas A.

    2015-01-01

    Purpose: In magnetic resonance-guided focused ultrasound (MRgFUS) therapies, the in situ characterization of the focal spot location and quality is critical. MR acoustic radiation force imaging (MR-ARFI) is a technique that measures the tissue displacement caused by the radiation force exerted by the ultrasound beam. This work presents a new technique to model the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model. Methods: When a steady-state point-source force acts internally in an infinite homogeneous medium, the displacement of the material in all directions is given by the Somigliana elastostatic tensor. The radiation force field, which is caused by absorption and reflection of the incident ultrasound intensity pattern, will be spatially distributed, and the tensor formulation takes the form of a convolution of a 3D Green’s function with the force field. The dynamic accumulation of MR phase during the ultrasound pulse can be theoretically accounted for through a time-of-arrival weighting of the Green’s function. This theoretical model was evaluated experimentally in gelatin phantoms of varied stiffness (125-, 175-, and 250-bloom). The acoustic and mechanical properties of the phantoms used as parameters of the model were measured using independent techniques. Displacements at focal depths of 30- and 45-mm in the phantoms were measured by a 3D spin echo MR-ARFI segmented-EPI sequence. Results: The simulated displacements agreed with the MR-ARFI measured displacements for all bloom values and focal depths with a normalized RMS difference of 0.055 (range 0.028–0.12). The displacement magnitude decreased and the displacement pattern broadened with increased bloom value for both focal depths, as predicted by the theory. Conclusions: A new technique that models the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model theory has been rigorously validated through comparison with experimentally obtained 3D displacement data in homogeneous gelatin phantoms using a 3D MR-ARFI sequence. The agreement of the experimentally measured and simulated results demonstrates the potential to use MR-ARFI displacement data in MRgFUS therapies. PMID:25652481

  3. A theoretical study of inertial cavitation from acoustic radiation force impulse (ARFI) imaging and implications for the mechanical index

    PubMed Central

    Church, Charles C.; Labuda, Cecille; Nightingale, Kathryn

    2014-01-01

    The mechanical index (MI) attempts to quantify the likelihood that exposure to diagnostic ultrasound will produce an adverse biological effect by a nonthermal mechanism. The current formulation of the MI implicitly assumes that the acoustic field is generated using the short pulse durations appropriate to B-mode imaging. However, acoustic radiation force impulse (ARFI) imaging employs high-intensity pulses up to several hundred acoustic periods long. The effect of increased pulse durations on the thresholds for inertial cavitation was studied computationally in water, urine, blood, cardiac and skeletal muscle, brain, kidney, liver and skin. The results show that while the effect of pulse duration on cavitation thresholds in the three liquids can be considerable, reducing them by, e.g., 6% – 24% at 1 MHz, the effect in tissue is minor. More importantly, the frequency dependence of the MI appears to be unnecessarily conservative, i.e., that the magnitude of the exponent on frequency could be increased to 0.75. Comparison of these theoretical results with experimental measurements suggests that some tissues do not contain the pre-existing, optimally sized bubbles assumed for the MI. This means that in these tissues the MI is not necessarily a strong predictor of the probability for an adverse biological effect. PMID:25592457

  4. Encoding degree testing in a 4f architecture

    NASA Astrophysics Data System (ADS)

    Amaya, Dafne; Tebaldi, Myrian; Torroba, Roberto; Bolognini, Nstor

    2011-08-01

    The distribution of the encrypted information at the output of an encoding system is of major concern. When the encrypted information is conveyed to the final user, the finite size of the recording medium affects the quality of the encoded information. In this case, we face possible information degradation when recovering. In the present contribution we focus our attention on the finite size of the recorder medium in an actual experimental situation. In order to improve the quality of the decrypted data, we study the role that both the scattering element size of the masks and the input object size play in the encrypting system. Therefore, we analyze the optimal spatial distribution of the encoded information at the output of a 4f encrypting system. We present examples that support our proposal.

  5. High-speed imaging, acoustic features, and aeroacoustic computations of jet noise from Strombolian (and Vulcanian) explosions

    NASA Astrophysics Data System (ADS)

    Taddeucci, J.; Sesterhenn, J.; Scarlato, P.; Stampka, K.; Del Bello, E.; Pena Fernandez, J. J.; Gaudin, D.

    2014-05-01

    High-speed imaging of explosive eruptions at Stromboli (Italy), Fuego (Guatemala), and Yasur (Vanuatu) volcanoes allowed visualization of pressure waves from seconds-long explosions. From the explosion jets, waves radiate with variable geometry, timing, and apparent direction and velocity. Both the explosion jets and their wave fields are replicated well by numerical simulations of supersonic jets impulsively released from a pressurized vessel. The scaled acoustic signal from one explosion at Stromboli displays a frequency pattern with an excellent match to those from the simulated jets. We conclude that both the observed waves and the audible sound from the explosions are jet noise, i.e., the typical acoustic field radiating from high-velocity jets. Volcanic jet noise was previously quantified only in the infrasonic emissions from large, sub-Plinian to Plinian eruptions. Our combined approach allows us to define the spatial and temporal evolution of audible jet noise from supersonic jets in small-scale volcanic eruptions.

  6. Cytochrome P450-Dependent Catabolism of Vitamin K: ?-Hydroxylation Catalyzed by Human CYP4F2 and CYP4F11

    PubMed Central

    Edson, Katheryne Z.; Prasad, Bhagwat; Unadkat, Jashvant D.; Suhara, Yoshitomo; Okano, Toshio; Guengerich, F. Peter

    2013-01-01

    Vitamin K plays an essential role in many biological processes including blood clotting, maintenance of bone health, and inhibition of arterial calcification. A menaquinone form of vitamin K, MK4, is increasingly recognized for its key roles in mitochondrial electron transport, as a ligand for the nuclear receptor SXR, which controls expression of genes involved in transport and metabolism of endo- and xenobiotics, and as a pharmacotherapeutic in the treatment of osteoporosis. Although cytochrome P450 (CYP) 4F2 activity is recognized as an important determinant of phylloquinone (K1) metabolism, the enzymes involved in menaquinone catabolism have not been studied previously. CYP4F2 and CYP4F11 were expressed and purified and found to be equally efficient as in vitro catalysts of MK4 ?-hydroxylation. CYP4F2, but not CYP4F11, catalyzed sequential metabolism of MK4 to the ?-acid without apparent release of the intermediate aldehyde. The ?-alcohol could also be metabolized to the acid by microsomal NAD+-dependent alcohol and aldehyde dehydrogenases. LC-MS/MS analysis of trypsinized human liver microsomes (using surrogate peptide approach) revealed mean concentrations of CYP4F2 and CYP4F11 to be 14.3 and 8.4 pmol/mg protein, respectively. Microsomal MK4 ?-hydroxylation activities correlated with the CYP4F2 V433M genotype but not CYP4F11 D446N genotype. Collectively, these data expand the lexicon of vitamin K ?-hydroxylases to include the orphan P450 CYP4F11 and identify a common variant, CYP4F2 (rs2108622), as a major pharmacogenetic variable influencing MK4 catabolism. PMID:24138531

  7. Apparatus for real-time acoustic imaging of Rayleigh-Bénard convection

    SciTech Connect

    Kuehn, Kerry, K.

    2008-10-28

    We have successfully designed, built and tested an experimental apparatus which is capable of providing the first real-time ultrasound images of Rayleigh-B\\'{e}nard convection in optically opaque fluids confined to large aspect ratio experimental cells. The apparatus employs a modified version of a commercially available ultrasound camera to capture images (30 frames per second) of flow patterns in a fluid undergoing Rayleigh Bénard convection. The apparatus was validated by observing convection rolls in 5cSt polydimethylsiloxane (PDMS) polymer fluid. Our first objective, after having built the apparatus, was to use it to study the sequence of transitions from diffusive to time--dependent heat transport in liquid mercury. The aim was to provide important information on pattern formation in the largely unexplored regime of very low Prandtl number fluids. Based on the theoretical stability diagram for liquid mercury, we anticipated that straight rolls should be stable over a range of Rayleigh numbers, between 1708 and approximately 1900. Though some of our power spectral densities were suggestive of the existence of weak convection, we have been unable to unambiguously visualize stable convection rolls above the theoretical onset of convection in liquid mercury. Currently, we are seeking ways to increase the sensitivity of our apparatus, such as (i) improving the acoustic impedance matching between our materials in the ultrasound path and (ii) reducing the noise level in our acoustic images due to turbulence and cavitation in the cooling fluids circulating above and below our experimental cell. If we are able to convincingly improve the sensitivity of our apparatus, and we still do not observe stable convection rolls in liquid mercury, then it may be the case that the theoretical stability diagram requires revision. In that case, either (i) straight rolls are not stable in a large aspect ratio cell at the Prandtl numbers associated with liquid mercury, or (ii) they are stable, but not in the region of the stability diagram which has been studied by this experimenter. Our second objective was to use the apparatus to study other optically opaque fluids. To this end, we have obtained the first ultrasound images of Rayleigh-Bénard convection in a ferrofluid (EFH1). This project has provided a vehicle for the scientific training of five undergraduate research assistants during the past four years. It allowed students at Wisconsin Lutheran College, a small undergraduate liberal arts college in Milwaukee, to become directly involved in a significant scientific project from its inception through publication of scientific results. The funding of this project has also strengthened the research and teaching infrastructure at the Wisconsin Lutheran College in three major ways. The project has funded the PI and his students in the design and construction of a major piece of scientific apparatus which is capable of performing novel studies of Rayleigh-Bénard convection in opaque fluids. With the acquisition of this apparatus, we are able to embark on a broad research program to study problems in pattern formation in alloys, ferro-fluids, opaque gels, and liquid metals under thermal or magnetic stresses. This project has allowed the PI to purchase auxiliary equipment necessary for establishing a fluid dynamics research laboratory at the College. And this project has served as an impetus for the College to invest in a new machine shop in the basement of the Science Building at the College in order to support this, and other, scientific projects at the College. The PI has presented work funded by this grant at physics and engineering colloquia at a nearby university and at the keynote presentation at an undergraduate research symposium at Wisconsin Lutheran College. Also, the work was featured in local magazine and newspaper articles, and is described on the PI's research webpage. Such scientific outreach serves to advance the cause of science by making it interesting and accessible to a wider audience, and to bring attention to the work done by the Office of Basic Energy Sciences of the Department of Energy.

  8. Optical-resolution photoacoustic imaging through thick tissue with a thin capillary as a dual optical-in acoustic-out waveguide

    NASA Astrophysics Data System (ADS)

    Simandoux, Olivier; Stasio, Nicolino; Gateau, Jérome; Huignard, Jean-Pierre; Moser, Christophe; Psaltis, Demetri; Bossy, Emmanuel

    2015-03-01

    We demonstrate the ability to guide high-frequency photoacoustic waves through thick tissue with a water-filled silica-capillary (150 μm inner diameter and 30 mm long). An optical-resolution photoacoustic image of a 30 μm diameter absorbing nylon thread was obtained by guiding the acoustic waves in the capillary through a 3 cm thick fat layer. The transmission loss through the capillary was about -20 dB, much lower than the -120 dB acoustic attenuation through the fat layer. The overwhelming acoustic attenuation of high-frequency acoustic waves by biological tissue can therefore be avoided by the use of a small footprint capillary acoustic waveguide for remote detection. We finally demonstrate that the capillary can be used as a dual optical-in acoustic-out waveguide, paving the way for the development of minimally invasive optical-resolution photoacoustic endoscopes free of any acoustic or optical elements at their imaging tip.

  9. Quantitative assessment of acoustic intensity in the focused ultrasound field using hydrophone and infrared imaging.

    PubMed

    Yu, Ying; Shen, Guofeng; Zhou, Yufeng; Bai, Jingfeng; Chen, Yazhu

    2013-11-01

    With the popularity of ultrasound therapy in clinics, characterization of the acoustic field is important not only to the tolerability and efficiency of ablation, but also for treatment planning. A quantitative method was introduced to assess the intensity distribution of a focused ultrasound beam using a hydrophone and an infrared camera with no prior knowledge of the acoustic and thermal parameters of the absorber or the configuration of the array elements. This method was evaluated in both theoretical simulations and experimental measurements. A three-layer model was developed to calculate the acoustic field in the absorber, the absorbed acoustic energy during the sonication and the consequent temperature elevation. Experiments were carried out to measure the acoustic pressure with the hydrophone and the temperature elevation with the infrared camera. The percentage differences between the derived results and the simulation are <4.1% for on-axis intensity and <21.1% for -6-dB beam width at heating times up to 360ms in the focal region of three phased-array ultrasound transducers using two different absorbers. The proposed method is an easy, quick and reliable approach to calibrating focused ultrasound transducers with satisfactory accuracy. PMID:23972377

  10. Imaging and characterizing shear wave and shear modulus under orthogonal acoustic radiation force excitation using OCT Doppler variance method.

    PubMed

    Zhu, Jiang; Qu, Yueqiao; Ma, Teng; Li, Rui; Du, Yongzhao; Huang, Shenghai; Shung, K Kirk; Zhou, Qifa; Chen, Zhongping

    2015-05-01

    We report on a novel acoustic radiation force orthogonal excitation optical coherence elastography (ARFOE-OCE) technique for imaging shear wave and quantifying shear modulus under orthogonal acoustic radiation force (ARF) excitation using the optical coherence tomography (OCT) Doppler variance method. The ARF perpendicular to the OCT beam is produced by a remote ultrasonic transducer. A shear wave induced by ARF excitation propagates parallel to the OCT beam. The OCT Doppler variance method, which is sensitive to the transverse vibration, is used to measure the ARF-induced vibration. For analysis of the shear modulus, the Doppler variance method is utilized to visualize shear wave propagation instead of Doppler OCT method, and the propagation velocity of the shear wave is measured at different depths of one location with the M scan. In order to quantify shear modulus beyond the OCT imaging depth, we move ARF to a deeper layer at a known step and measure the time delay of the shear wave propagating to the same OCT imaging depth. We also quantitatively map the shear modulus of a cross-section in a tissue-equivalent phantom after employing the B scan. PMID:25927794

  11. Neutralization epitopes on rotavirus SA11 4fM outer capsid proteins.

    PubMed Central

    Gorziglia, M; Larralde, G; Ward, R L

    1990-01-01

    The VP7 and VP4 genes of seven antigenic mutants of simian rotavirus SA11 4fM (serotype 3) selected after 39 passages in the presence of SA11 4fM hyperimmune antiserum, were sequenced. Nucleotide sequence analysis indicated the following. (i) Twice as many amino acid substitutions occurred in the VP7 protein than in VP4, which has a molecular weight twice that of VP7. (ii) Most amino acid changes that occurred clustered in six variable regions of VP7 and in two variable regions of VP4; these variable regions may represent immunodominant epitopes. (iii) Most amino acid substitutions that occurred in VP7 and VP4 of these mutants were also observed in antigenic mutants selected with neutralizing monoclonal antibodies (NMAbs); however, some amino acid substitutions occurred that were not selected for NMAbs. (iv) On VP7, some of the neutralization epitopes appeared to be interrelated because amino acid substitution in one site affected binding of specific NMAbs to other sites, while other neutralization epitopes on VP7 appeared to be independent, in that amino acid substitution in one site did not affect the binding of NMAbs to another distant site. Images PMID:1696640

  12. ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS

    SciTech Connect

    Thurman E. Scott, Jr., Ph.D.; Younane Abousleiman, Ph.D.; Musharraf Zaman, Ph.D., P.E.

    2001-07-01

    Mechanically weak formations, such as chalks, high porosity sandstones, and marine sediments, pose significant problems for oil and gas operators. Problems such as compaction, subsidence, and loss of permeability can affect reservoir production operations. For example, the unexpected subsidence of the Ekofisk chalk in the North Sea required over one billion dollars to re-engineer production facilities to account for losses created during that compaction (Sulak 1991). Another problem in weak formations is that of shallow water flows (SWF). Deep water drilling operations sometimes encounter cases where the marine sediments, at shallow depths just below the seafloor, begin to uncontrollably flow up and around the drill pipe. SWF problems created a loss of $150 million for the Ursa development project in the U.S. Gulf Coast SWF (Furlow 1998a,b; 1999a,b). The goal of this project is to provide a database on both the rock mechanical properties and the geophysical properties of weak rocks and sediments. These could be used by oil and gas companies to detect, evaluate, and alleviate potential production and drilling problems. The results will be useful in, for example, pre-drill detection of events such as SWF's by allowing a correlation of seismic data (such as hazard surveys) to rock mechanical properties. The data sets could also be useful for 4-D monitoring of the compaction and subsidence of an existing reservoir and imaging the zones of damage. During the second quarter of the project the research team has: (1) completed acoustic sensor construction, (2) conducted reconnaissance tests to map the deformational behaviors of the various rocks, (3) developed a sample assembly for the measurement of dynamic elastic and poroelastic parameters during triaxial testing, and (4) conducted a detailed review of the scientific literature and compiled a bibliography of that review. During the first quarter of the project the research team acquired several rock types for testing including: (a) Danian chalk, (b) Cordoba Cream limestone, (c) Indiana limestone, (d) Ekofisk chalk, (e) Oil Creek sandstone, (f) unconsolidated Oil Creek sand, and (g) unconsolidated Brazos river sand. During the second quarter experiments were begun on these rock types. A series of reconnaissance experiments have been carried out on all but the Ekofisk (for which there is a preliminary data set already inhouse). A series of triaxial tests have been conducted on the Danian chalk, the Cordoba Cream limestone, the Indiana limestone, and sand samples to make a preliminary determination of the deformational mechanisms present in these samples.

  13. Integration of Acoustic Radiation Force and Optical Imaging for Blood Plasma Clot Stiffness Measurement

    PubMed Central

    Wang, Caroline W.; Perez, Matthew J.; Helmke, Brian P.; Viola, Francesco; Lawrence, Michael B.

    2015-01-01

    Despite the life-preserving function blood clotting serves in the body, inadequate or excessive blood clot stiffness has been associated with life-threatening diseases such as stroke, hemorrhage, and heart attack. The relationship between blood clot stiffness and vascular diseases underscores the importance of quantifying the magnitude and kinetics of bloods transformation from a fluid to a viscoelastic solid. To measure blood plasma clot stiffness, we have developed a method that uses ultrasound acoustic radiation force (ARF) to induce micron-scaled displacements (1-500 ?m) on microbeads suspended in blood plasma. The displacements were detected by optical microscopy and took place within a micro-liter sized clot region formed within a larger volume (2 mL sample) to minimize container surface effects. Modulation of the ultrasound generated acoustic radiation force allowed stiffness measurements to be made in blood plasma from before its gel point to the stage where it was a fully developed viscoelastic solid. A 0.5 wt % agarose hydrogel was 9.8-fold stiffer than the plasma (platelet-rich) clot at 1 h post-kaolin stimulus. The acoustic radiation force microbead method was sensitive to the presence of platelets and strength of coagulation stimulus. Platelet depletion reduced clot stiffness 6.9 fold relative to platelet rich plasma. The sensitivity of acoustic radiation force based stiffness assessment may allow for studying platelet regulation of both incipient and mature clot mechanical properties. PMID:26042775

  14. Acoustic profiles and images of the Palos Verdes Margin: Implications concerning deposition from the White's Point outfall

    SciTech Connect

    Hampton, M A.; Karl, H; Murray, Christopher J. )

    2001-12-01

    Subbottom profiles and sidescan-sonar images collected on and around the Palos Verdes shelf show a surficial deposit interpreted to contain effluent from the White's Point diffusers, as well as showing several geologic features that affect the deposit's distribution. The effluent-affected deposit is visible in high-resolution subbottom profiles on the shelf and the adjacent San Pedro basin slope to water depths of 170 m. It has a maximum thickness of 75 cm and was mapped acoustically over an area of 10.8 km{sup 2}, which encompasses a volume of about 3.2 million m{sup 3}. The deposit's basal reflector is acoustically distinct over most of the mapped area, implying that the deposit has not been extensively mixed across its base, perhaps being relatively free of reworking since its initial deposition. Nearshore, the basal reflector is weak and fades away toward land, which could result from syndepositional intermixing of coarse native sediment (particularly from the Portuguese Bend landslide) with effluent in the high-energy nearshore zone, or postdepositionally by physical (wave) or biological mixing across the interface. The geometry of the deposit implies that effluent is dispersed primarily in a northwesterly and seaward direction from the diffusers. Dispersal across the shelf break is in some places strongly affected by topography, particularly by submarine canyons. The deposit overlies stratified and unstratified Quaternary sediment, up to 30 m thick, that in turn overlies the irregular erosional surface of deformed Miocene bedrock that crops out in places on the shelf and upper basin slope. The effluent-affected deposit rests on potentially unstable landslide deposits on the San Pedro basin slope. The acoustic profiles and side-scan images show evidence for active and inactive vents, probably of hot water and gas, some of which are within the boundary of the effluent-affected sediment deposit and could disrupt it if seepage occurs.

  15. Acoustic profiles and images of the Palos Verdes margin: Implications concerning deposition from the White's Point outfall

    USGS Publications Warehouse

    Hampton, M.A.; Karl, Herman A.; Murray, C.J.

    2002-01-01

    Subbottom profiles and sidescan-sonar images collected on and around the Palos Verdes Shelf show a surficial deposit interpreted to contain effluent from the White's Point diffusers, as well as showing several geologic features that affect the deposit's distribution. The effluent-affected deposit is visible in high-resolution subbottom profiles on the shelf and the adjacent San Pedro basin slope to water depths of 170 m. It has a maximum thickness of 75 cm and was mapped acoustically over an area of 10.8 km2, which encompasses a volume of about 3.2 million m3. The deposit's basal reflector is acoustically distinct over most of the mapped area. implying that the deposit has not been extensively mixed across its base, perhaps being relatively free of reworking since its initial deposition. Nearshore, the basal reflector is weak and fades away toward land, which could result from syndepositional intermixing of coarse native sediment (particularly from the Portuguese Bend landslide) with effluent in the high-energy nearshore zone, or postdepositionally by physical (wave) or biological mixing across the interface. The geometry of the deposit implies that effluent is dispersed primarily in a northwesterly and seaward direction from the diffusers. Dispersal across the shelf break is in some places strongly affected by topography, particularly by submarine canyons. The deposit overlies stratified and unstratified Quaternary sediment, up to 30m thick, that in turn overlies the irregular erosional surface of deformed Miocene bedrock that crops out in places on the shelf and upper basin slope. The effluent-affected deposit rests on potentially unstable landslide deposits on the San Pedro basin slope. The acoustic profiles and side-scan images show evidence for active and inactive vents, probably of hot water and gas, some of which are within the boundary of the effluent-affected sediment deposit and could disrupt it if seepage occurs. ?? 2002 Elsevier Science Ltd. All rights reserved.

  16. Gas-phase structures of perfluorotetrahydrothiophene, c-C 4F 8S, tetrahydrothiophene-1-oxide, c-C 4F 8SO, and tetrahydrothiophene-1,1-dioxide, c-C 4F 8SO 2

    NASA Astrophysics Data System (ADS)

    Mack, Hans-Georg; Oberhammer, Heinz; Shreeve, Jean'ne M.; Xia, X.-B.

    1989-05-01

    The geometric structures of the three title compounds have been determined by gas-phase electron diffraction. In all cases the five-membered rings are strongly puckered and possess half chair conformations with the following geometric parameters ( ra values with 3? error limits). c-C 4F 8S: (C?C) mean=1.548(4), S?C=1.822(4) , CSC=94.5(3), SCC=107.4(3), CCC=106.4(4) and puckering amplitude q=0.411(8) . c-C 4F 8SO: (C?C) mean=1.553(5), S?C=1.903(4) , CSC=89.4(4), SCC=110.2(4), CCC=106.5(6), q=0.403(8) . c-C 4F 8SO 2: (C?C) mean=1.556(6), S?C=1.882(7) , CSC=93.2(10), SCC=107.7(10), CCC=107.9(12), q=0.382(10) . Comparison with the analogous protonated rings reveals that upon fluorination the degree of puckering decreases slightly in c-C 4F 8S and c-C 4F 8SO, whereas it increases strongly in c-C 4F 8SO 2.

  17. Acoustic neuroma

    MedlinePLUS

    Vestibular schwannoma; Tumor - acoustic; Cerebellopontine angle tumor; Angle tumor ... Acoustic neuromas have been linked with the genetic disorder neurofibromatosis type 2 (NF2). Acoustic neuromas are uncommon.

  18. Clinical feasibility study of combined opto-acoustic and ultrasonic imaging modality providing coregistered functional and anatomical maps of breast tumors

    NASA Astrophysics Data System (ADS)

    Zalev, Jason; Clingman, Bryan; Smith, Remie J.; Herzog, Don; Miller, Tom; Stavros, A. Thomas; Ermilov, Sergey; Conjusteau, André; Tsyboulski, Dmitri; Oraevsky, Alexander A.; Kist, Kenneth; Dornbluth, N. C.; Otto, Pamela

    2013-03-01

    We report on findings from the clinical feasibility study of the ImagioTM. Breast Imaging System, which acquires two-dimensional opto-acoustic (OA) images co-registered with conventional ultrasound using a specialized duplex hand-held probe. Dual-wavelength opto-acoustic technology is used to generate parametric maps based upon total hemoglobin and its oxygen saturation in breast tissues. This may provide functional diagnostic information pertaining to tumor metabolism and microvasculature, which is complementary to morphological information obtained with conventional gray-scale ultrasound. We present co-registered opto-acoustic and ultrasonic images of malignant and benign tumors from a recent clinical feasibility study. The clinical results illustrate that the technology may have the capability to improve the efficacy of breast tumor diagnosis. In doing so, it may have the potential to reduce biopsies and to characterize cancers that were not seen well with conventional gray-scale ultrasound alone.

  19. Comparison of temporal and spectral scattering methods using acoustically large breast models derived from magnetic resonance images

    PubMed Central

    Hesford, Andrew J.; Tillett, Jason C.; Astheimer, Jeffrey P.; Waag, Robert C.

    2014-01-01

    Accurate and efficient modeling of ultrasound propagation through realistic tissue models is important to many aspects of clinical ultrasound imaging. Simplified problems with known solutions are often used to study and validate numerical methods. Greater confidence in a time-domain k-space method and a frequency-domain fast multipole method is established in this paper by analyzing results for realistic models of the human breast. Models of breast tissue were produced by segmenting magnetic resonance images of ex vivo specimens into seven distinct tissue types. After confirming with histologic analysis by pathologists that the model structures mimicked in vivo breast, the tissue types were mapped to variations in sound speed and acoustic absorption. Calculations of acoustic scattering by the resulting model were performed on massively parallel supercomputer clusters using parallel implementations of the k-space method and the fast multipole method. The efficient use of these resources was confirmed by parallel efficiency and scalability studies using large-scale, realistic tissue models. Comparisons between the temporal and spectral results were performed in representative planes by Fourier transforming the temporal results. An RMS field error less than 3% throughout the model volume confirms the accuracy of the methods for modeling ultrasound propagation through human breast. PMID:25096103

  20. VHMPID RICH prototype using pressurized C4F8O radiator gas and VUV photon detector

    NASA Astrophysics Data System (ADS)

    Acconcia, T. V.; Agcs, A. G.; Barile, F.; Barnafldi, G. G.; Bellwied, R.; Bencdi, G.; Bencze, G.; Bernyi, D.; Boldizsr, L.; Chattopadhyay, S.; Chinellato, D. D.; Cindolo, F.; Cossyleon, K.; Das, D.; Das, K.; Das-Bose, L.; Dash, A. K.; D`Ambrosio, S.; De Cataldo, G.; De Pasquale, S.; Di Bari, D.; Di Mauro, A.; Fut, E.; Garcia-Solis, E.; Hamar, G.; Harton, A.; Iannone, G.; Jimenez, R. T.; Kim, D. W.; Kim, J. S.; Knospe, A.; Kovcs, L.; Lvai, P.; Markert, C.; Martinengo, P.; Molnr, L.; Nappi, E.; Olh, L.; Pai?, G.; Pastore, C.; Patimo, G.; Patino, M. E.; Peskov, V.; Pinsky, L.; Piuz, F.; Pochybov, S.; Sgura, I.; Sinha, T.; Song, J.; Takahashi, J.; Timmins, A.; Van Beelen, J. B.; Varga, D.; Volpe, G.; Weber, M.; Xaplanteris, L.; Yi, J.; Yoo, I.-K.

    2014-12-01

    A small-size prototype of a new Ring Imaging Cherenkov (RICH) detector using for the first time pressurized C4F8O radiator gas and a photon detector consisting of MWPC equipped with a CsI photocathode has been built and tested at the PS accelerator at CERN. It contained all the functional elements of the detector proposed as Very High Momentum Particle Identification (VHMPID) upgrade for the ALICE experiment at LHC to provide charged hadron track-by-track identification in the momentum range starting from 5 potentially up to 25 GeV/c. In the paper the equipment and its elements are described and some characteristic test results are shown.

  1. Comparative evaluation of ultrasonic lenses and electric point contacts for acoustic flux imaging in piezoelectric single crystals

    NASA Astrophysics Data System (ADS)

    Twerdowski, E.; Pluta, M.; Wannemacher, R.; Grill, W.

    2008-03-01

    Conducting micro-spheres approximating point probes have been employed to piezoelectrically excite and detect ultrasonic wave packages in anisotropic single crystals. Imaging based on the detection of magnitude and phase is performed in transmission. The experimental data can be used for the determination of the elastic constants of the material. Here we compare this approach with imaging using conventional ultrasonic lenses and water as a coupling fluid. The large bandwidth and the absence of internal lens echoes in the Coulomb excitation and detection scheme permit unperturbed monitoring of multiple echoes in plane-parallel samples and the detailed investigation of mode conversion processes of longitudinal and transverse waves at the surfaces of the crystal. Due to differences in the coupling between the probes and the ultrasound in the sample, excitation of ultrasound by an acoustic lens or an electrical point contact, respectively, result in noticeably different phonon focusing patterns. This is illustrated for lithium niobate single crystals.

  2. Experimental Study of High-Range-Resolution Medical Acoustic Imaging for Multiple Target Detection by Frequency Domain Interferometry

    NASA Astrophysics Data System (ADS)

    Kimura, Tomoki; Taki, Hirofumi; Sakamoto, Takuya; Sato, Toru

    2009-07-01

    We employed frequency domain interferometry (FDI) for use as a medical acoustic imager to detect multiple targets with high range resolution. The phase of each frequency component of an echo varies with the frequency, and target intervals can be estimated from the phase variance. This processing technique is generally used in radar imaging. When the interference within a range gate is coherent, the cross correlation between the desired signal and the coherent interference signal is nonzero. The Capon method works under the guiding principle that output power minimization cancels the desired signal with a coherent interference signal. Therefore, we utilize frequency averaging to suppress the correlation of the coherent interference. The results of computational simulations using a pseudoecho signal show that the Capon method with adaptive frequency averaging (AFA) provides a higher range resolution than a conventional method. These techniques were experimentally investigated and we confirmed the effectiveness of the proposed method of processing by FDI.

  3. Feasibility of Near Real-Time Lesion Assessment During Radiofrequency Catheter Ablation in Humans Using Acoustic Radiation Force Impulse Imaging

    PubMed Central

    Bahnson, Tristram D.; Eyerly, Stephanie A.; Hollender, Peter J.; Doherty, Joshua R.; Kim, Young-Joong; Trahey, Gregg E.; Wolf, Patrick D.

    2015-01-01

    Background Visual confirmation of radiofrequency ablation (RFA) lesions during clinical cardiac ablation procedures could improve procedure efficacy, safety, and efficiency. It was previously shown that acoustic radiation force impulse (ARFI) imaging can identify RFA lesions in vitro and in vivo in an animal model. This is the “first-in-human” feasibility demonstration of intracardiac ARFI imaging of RFA lesions in patients undergoing catheter ablation for atrial flutter (AFL) or atrial fibrillation (AF). Methods and Results Patients scheduled for right atrial (RA) ablation for AFL or left atrial (LA) ablation for drug refractory AF were eligible for imaging. Diastole-gated intracardiac ARFI images were acquired using one of two equipment configurations: (1) a Siemens ACUSON S2000™ ultrasound scanner and 8/10Fr AcuNav™ ultrasound catheter, or (2) a CARTO 3™ integrated Siemens SC2000™ and 10Fr SoundStar™ ultrasound catheter. A total of 11 patients (AFL = 3; AF = 8) were imaged. ARFI images were acquired of ablation target regions, including the RA cavotricuspid isthmus (CTI), and the LA roof, pulmonary vein ostia, posterior wall, posterior mitral valve annulus, and the ridge between the pulmonary vein and LA appendage. ARFI images revealed increased relative myocardial stiffness at ablation catheter contact sites after RFA and at anatomical mapping-tagged RFA treatment sites. Conclusions ARFI images from a pilot group of patients undergoing catheter ablation for AFL and AF demonstrate the ability of this technique to identify intra-procedure RFA lesion formation. The results encourage further refinement of ARFI imaging clinical tools and continued investigation in larger clinical trials. PMID:25132292

  4. The Acoustic Lens Design and in Vivo Use of a Multifunctional Catheter Combining Intracardiac Ultrasound Imaging and Electrophysiology Sensing

    PubMed Central

    Stephens, Douglas N.; Cannata, Jonathan; Liu, Ruibin; Zhao, Jian Zhong; Shung, K. Kirk; Nguyen, Hien; Chia, Raymond; Dentinger, Aaron; Wildes, Douglas; Thomenius, Kai E.; Mahajan, Aman; Shivkumar, Kalyanam; Kim, Kang; ODonnell, Matthew; Sahn, David

    2009-01-01

    A multifunctional 9F intracardiac imaging and electrophysiology mapping catheter was developed and tested to help guide diagnostic and therapeutic intracardiac electrophysiology (EP) procedures. The catheter tip includes a 7.25-MHz, 64-element, side-looking phased array for high resolution sector scanning. Multiple electrophysiology mapping sensors were mounted as ring electrodes near the array for electrocardiographic synchronization of ultrasound images. The catheter array elevation beam performance in particular was investigated. An acoustic lens for the distal tip array designed with a round cross section can produce an acceptable elevation beam shape; however, the velocity of sound in the lens material should be approximately 155 m/s slower than in tissue for the best beam shape and wide bandwidth performance. To help establish the catheters unique ability for integration with electrophysiology interventional procedures, it was used in vivo in a porcine animal model, and demonstrated both useful intracardiac echocardiographic visualization and simultaneous 3-D positional information using integrated electroanatomical mapping techniques. The catheter also performed well in high frame rate imaging, color flow imaging, and strain rate imaging of atrial and ventricular structures. PMID:18407850

  5. Evidence from acoustic imaging for submarine volcanic activity in 2012 off the west coast of El Hierro (Canary Islands, Spain)

    NASA Astrophysics Data System (ADS)

    Prez, Nemesio M.; Somoza, Luis; Hernndez, Pedro A.; de Vallejo, Luis Gonzlez; Len, Ricardo; Sagiya, Takeshi; Biain, Ander; Gonzlez, Francisco J.; Medialdea, Teresa; Barrancos, Jos; Ibez, Jess; Sumino, Hirochika; Nogami, Kenji; Romero, Carmen

    2014-12-01

    We report precursory geophysical, geodetic, and geochemical signatures of a new submarine volcanic activity observed off the western coast of El Hierro, Canary Islands. Submarine manifestation of this activity has been revealed through acoustic imaging of submarine plumes detected on the 20-kHz chirp parasound subbottom profiler (TOPAS PS18) mounted aboard the Spanish RV Hesprides on June 28, 2012. Five distinct "filament-shaped" acoustic plumes emanating from the flanks of mounds have been recognized at water depth between 64 and 88 m on a submarine platform located NW El Hierro. These plumes were well imaged on TOPAS profiles as "flares" of high acoustic contrast of impedance within the water column. Moreover, visible plumes composed of white rafts floating on the sea surface and sourcing from the location of the submarine plumes were reported by aerial photographs on July 3, 2012, 5 days after acoustic plumes were recorded. In addition, several geophysical and geochemical data support the fact that these submarine vents were preceded by several precursory signatures: (i) a sharp increase of the seismic energy release and the number of daily earthquakes of magnitude ?2.5 on June 25, 2012, (ii) significant vertical and horizontal displacements observed at the Canary Islands GPS network (Nagoya University-ITER-GRAFCAN) with uplifts up to 3 cm from June 25 to 26, 2012, (iii) an anomalous increase of the soil gas radon activity, from the end of April until the beginning of June reaching peak values of 2.7 kBq/m3 on June 3, 2012, and (iv) observed positive peak in the air-corrected value of 3He/4He ratio monitored in ground waters (8.5 atmospheric 3He/4He ratio ( R A)) at the northwestern El Hierro on June 16, 2012. Combining these submarine and subaerial information, we suggest these plumes are the consequence of submarine vents exhaling volcanic gas mixed with fine ash as consequence of an event of rapid rise of volatile-rich magma beneath the NW submarine ridge of El Hierro. These precursory signals have revealed important to improve and optimize the detection of early warning signals of volcanic unrest episodes at El Hierro.

  6. Study of the laser induced acoustic under water source aim at imaging and detecting

    NASA Astrophysics Data System (ADS)

    Yu, Xiaotang; Xin, Jianguo; Chen, Jiabin

    2015-11-01

    This paper addresses itself to the problem of interaction mechanism of laser induced acoustic source under water. The main photo-acoustic mechanisms include thermal expansion, vaporization and optical breakdown as well as the photon beam pressure. We integrate these into a compound model and compare numerical calculation and simulation results with the existing experimental data. The different energy density thresholds between different mechanisms are calculated. We optimize original thermal expansion by considering various laser pulse-shapes especially Gaussian laser. When discussing vaporization, random bubbles distribution is studied instead of single bubble alone for the first time. Detection distance, pulse duration, laser energy and spot size in heating area all have effect on sound filed intensity, which are studied through this paper.

  7. Effects of using inclined parametric echosounding on sub-bottom acoustic imaging and advances in buried object detection

    NASA Astrophysics Data System (ADS)

    Schneider von Deimling, Jens; Held, Philipp; Feldens, Peter; Wilken, Dennis

    2015-12-01

    This study reports an adaptation of a parametric echosounder system using 15 kHz as secondary frequency to investigate the angular response of sub-bottom backscatter strength of layered mud, providing a new method for enhanced acoustic detection of buried targets. Adaptions to achieve both vertical (0°) and non-vertical inclination (1-15°, 30°, 45° and 60°) comprise mechanical tilting of the acoustic transducer and electronic beam steering. Data were acquired at 18 m water depth at a study site characterized by a flat, muddy seafloor where a 0.1 m diameter power cable lies 1-2 m below the seafloor. Surveying the cable with vertical incidence revealed that the buried cable can hardly be discriminated against the backscatter strength of the layered mud. However, the backscatter strength of layered mud decreases strongly at >3±0.5° incidence and the layered mud echo pattern vanishes beyond 5°. As a consequence, the backscatter pattern of the buried cable is very pronounced in acoustic images gathered at 15°, 30°, 45° and 60° incidence. The size of the cable echo pattern increases linearly with incidence. These effects are attributed to reflection loss from layered mud at larger incidence and to the scattering of the 0.1 m diameter buried cable. Data analyses support the visual impression of superior detection of the cable with an up to 2.6-fold increase of the signal-to-noise ratio at 40° incidence compared to the vertical incidence case.

  8. The screening of 4f moments and delocalization in the compressed light rare earths

    SciTech Connect

    McMahan, A K; Scalettar, R T; Jarrell, M

    2009-08-19

    Spin and charge susceptibilities and the 4f{sup n}, 4f{sup n{+-}1} configuration weights are calculated for compressed Ce (n=1), Pr (n=2), and Nd (n=3) metals using dynamical mean field theory combined with the local-density approximation. At ambient and larger volumes these trivalent rare earths are pinned at sharp 4f{sup n} configurations, their 4f moments assume atomic-limiting values, are unscreened, and the 4f charge fluctuations are small indicating little f state density near the Fermi level. Under compresssion there is dramatic screening of the moments and an associated increase in both the 4f charge fluctuations and static charge susceptibility. These changes are coincident with growing weights of the 4f{sup n-1} configurations, which it is argued are better measures of delocalization than the 4f{sup n+1} weights which are compromised by an increase in the number of 4f electrons caused by rising 6s, 6p bands. This process is continuous and prolonged as a function of volume, with strikingly similarity among the three rare earths, aside from the effects moderating and shifting to smaller volumes for the heavier members. The observed {alpha}-{gamma} collapse in Ce occurs over the large-volume half of this evolution, the Pr analog at smaller volumes, and Nd has no collapse.

  9. Detecting the activation of a self-healing mechanism in concrete by acoustic emission and digital image correlation.

    PubMed

    Tsangouri, E; Aggelis, D G; Van Tittelboom, K; De Belie, N; Van Hemelrijck, D

    2013-01-01

    Autonomous crack healing in concrete is obtained when encapsulated healing agent is embedded into the material. Cracking damage in concrete elements ruptures the capsules and activates the healing process by healing agent release. Previously, the strength and stiffness recovery as well as the sealing efficiency after autonomous crack repair was well established. However, the mechanisms that trigger capsule breakage remain unknown. In parallel, the conditions under which the crack interacts with embedded capsules stay black-box. In this research, an experimental approach implementing an advanced optical and acoustic method sets up scopes to monitor and justify the crack formation and capsule breakage of concrete samples tested under three-point bending. Digital Image Correlation was used to visualize the crack opening. The optical information was the basis for an extensive and analytical study of the damage by Acoustic Emission analysis. The influence of embedding capsules on the concrete fracture process, the location of capsule damage, and the differentiation between emissions due to capsule rupture and crack formation are presented in this research. A profound observation of the capsules performance provides a clear view of the healing activation process. PMID:24381518

  10. Investigation of the acoustic field in a standing wave thermoacoustic refrigerator using time-resolved particule image velocimetry

    NASA Astrophysics Data System (ADS)

    Blanc-Benon, Ph.; Poignand, G.; Jondeau, E.

    2012-09-01

    In thermoacoustic devices, the full understanding of the heat transfer between the stack and the heat exchangers is a key issue to improve the global efficiency of these devices. The goal of this paper is to investigate the vortex structures, which appear at the stack plates extremities and may impact the heat transfer. Here, the aerodynamic field between a stack and a heat exchanger is characterised with a time-resolved particle image velocimetry (TR- PIV) set-up. Measurements are performed in a standing wave thermoacoustic refrigerator operating at a frequency of 200 Hz. The employed TR-PIV set-up offers the possibility to acquire 3000 instantaneous velocity fields at a frequency of 3125 Hz (15 instantaneous velocity fields per acoustic period). Measurements show that vortex shedding can occur at high pressure level, when a nonlinear acoustic regime preveals, leading to an additional heating generated by viscous dissipation in the gap between the stack and the heat exchangers and a loss of efficiency.

  11. Real-time algorithm for acoustic imaging with a microphone array.

    PubMed

    Huang, Xun

    2009-05-01

    Acoustic phased array has become an important testing tool in aeroacoustic research, where the conventional beamforming algorithm has been adopted as a classical processing technique. The computation however has to be performed off-line due to the expensive cost. An innovative algorithm with real-time capability is proposed in this work. The algorithm is similar to a classical observer in the time domain while extended for the array processing to the frequency domain. The observer-based algorithm is beneficial mainly for its capability of operating over sampling blocks recursively. The expensive experimental time can therefore be reduced extensively since any defect in a testing can be corrected instantaneously. PMID:19425621

  12. Development of a Doppler Acoustic Imaging System for Borehole Wall to Evaluate Fluid Flow Distribution around Subsurface Fractures

    NASA Astrophysics Data System (ADS)

    Saito, Jin; Niitsuma, Hiroaki

    2001-05-01

    We are in the process of developing a doppler borehole televiewer (DBHTV) which quantitatively evaluates the permeability of independent subsurface fractures in a borehole. The system employs an ultrasonic pulsed Doppler method, and is compatible with the conventional acoustic borehole imaging system called borehole televiewer (BHTV). Using the DBHTV, back-scattered waves from fine particles in the borehole fluid such as drill mud or cuttings in a water filled borehole are detected along with the reflected waves from the borehole wall, and the Doppler shift of the back-scattered waves is used to estimate the fluid velocity. A method to estimate the distribution of Doppler shift was examined using a laboratory experimental model. An attempt to locate the sampling volume and a method to quantitatively estimate the flow velocity by scanning the transducer are examined. This study shows that the location of permeable fractures, the distribution of fluid velocity and the fluid volume can be visualized using the DBHTV.

  13. Gas-coupled laser acoustic detection as a non-contact line detector for photoacoustic and ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Johnson, Jami L.; van Wijk, Kasper; Caron, James N.; Timmerman, Miriam

    2016-02-01

    Conventional contacting transducers for ultrasonic wave detection are highly sensitive and tuned for real-time imaging with fixed array geometries. However, optical detection provides an alternative to contacting transducers when a small sensor footprint, a large frequency bandwidth, or non-contacting detection is required. Typical optical detection relies on a Doppler-shifted reflection of light from the target, but gas coupled-laser acoustic detection (GCLAD) provides an alternative optical detection method for photoacoustic (PA) and ultrasound imaging that does not involve surface reflectivity. Instead, GCLAD is a line-detector that measures the deflection of an optical beam propagating parallel to the sample, as the refractive index of the air near the sample is affected by particle displacement on the sample surface. We describe the underlying principles of GCLAD and derive a formula for quantifying the surface displacement from a remote GCLAD measurement. We discuss a design for removing the location-dependent displacement bias along the probe beam and a method for measuring the attenuation coefficient of the surrounding air. GCLAD results are used to quantify the surface displacement in a laser-ultrasound experiment, which shows 94% agreement to line-integrated data from a commercial laser vibrometer point detector. Finally, we demonstrate the feasibility of PA imaging of an artery-sized absorber using a detector 5.8 cm from a phantom surface.

  14. Reducing the Impacts of Hydroelectric Dams on Juvenile Anadromous Fishes: Bioengineering Evaluations Using Acoustic Imaging in the Columbia River, USA

    SciTech Connect

    Johnson, Gary E.; Ploskey, Gene R.; Hedgepeth, J.; Khan, Fenton; Mueller, Robert P.; Nagy, William T.; Richmond, Marshall C.; Weiland, Mark A.

    2008-07-29

    Dams impact the survival of juvenile anadromous fishes by obstructing migration corridors, lowering water quality, delaying migrations, and entraining fish in turbine discharge. To reduce these impacts, structural and operational modifications to dams such as voluntary spill discharge, turbine intake guidance screens, and surface flow outletsare instituted. Over the last six years, we have used acoustic imaging technology to evaluate the effects of these modifications on fish behavior, passage rates, entrainment zones, and fish/flow relationships at hydroelectric projects on the Columbia River. The imaging technique has evolved from studies documenting simple movement patterns to automated tracking of images to merging and analysis with concurrent hydraulic data. This chapter chronicles this evolution and shows how the information gleaned from the scientific evaluations has been applied to improve passage conditions for juvenile salmonids. We present data from Bonneville and The Dalles dams that document fish behavior and entrainment zones at sluiceway outlets (14 to 142 m3/s), fish passage rates through a gap at a turbine intake screen, and the relationship between fish swimming effort and hydraulic conditions. Dam operators and fisheries managers have applied these data to support decisions on operational and structural changes to the dams for the benefit of anadromous fish populations in the Columbia River basin.

  15. L-4F Alters Hyperlipidemic (but not Normal) Mouse Plasma to Reduce Platelet Aggregation

    PubMed Central

    Buga, Georgette M.; Navab, Mohamad; Imaizumi, Satoshi; Reddy, Srinivasa T.; Yekta, Babak; Hough, Greg; Chanslor, Shawn; Anantharamaiah, G.M.; Fogelman, Alan M.

    2010-01-01

    Objective Hyperlipidemia is associated with platelet hyper-reactivity. We hypothesized that L-4F, an apoA-I mimetic peptide, would inhibit platelet aggregation in hyperlipidemic mice. Methods and Results Injecting L-4F into apoE null and LDL receptor null mice resulted in a significant reduction in platelet aggregation in response to agonists but there was no reduction in platelet aggregation after injection of L-4F into wild-type (WT) mice. Consistent with these results, injection of L-4F into apoE null mice prolonged bleeding time but not in WT mice. Incubating L-4F in vitro with apoE null platelet rich plasma also resulted in decreased platelet aggregation. However, incubating washed platelets from either apoE null or WT mice with L-4F did not alter aggregation. Compared to wild-type mice, unstimulated platelets from apoE null mice contained significantly more 12-HETE, thromboxane A2 (TXA2), prostaglandins D2 (PGD2) and E2 (PGE2). In response to agonists, platelets from L-4F treated apoE null mice formed significantly less TXA2, PGD2 PGE2, and 12-HETE. Conclusions By binding plasma oxidized lipids that cause platelet hyper-reactivity in hyperlipidemic mice, L-4F decreases platelet aggregation. PMID:19965777

  16. Bioenergetic programming of macrophages by the apolipoprotein A-I mimetic peptide 4F

    PubMed Central

    Datta, Geeta; Kramer, Philip A.; Johnson, Michelle S.; Sawada, Hirotaka; Smythies, Lesley E.; Crossman, David K.; Chacko, Balu; Ballinger, Scott W.; Westbrook, David G.; Mayakonda, Palgunachari; Anantharamaiah, G. M.; Darley-Usmar, Victor M.; White, C. Roger

    2015-01-01

    The apoA-I (apolipoprotein A-I) mimetic peptide 4F favours the differentiation of human monocytes to an alternatively activated M2 phenotype. The goal of the present study was to test whether the 4F-mediated differentiation of MDMs (monocyte-derived macrophages) requires the induction of an oxidative metabolic programme. 4F treatment induced several genes in MDMs that play an important role in lipid metabolism, including PPAR? (peroxisome-proliferator-activated receptor ?) and CD36. Addition of 4F was associated with a significant increase in FA (fatty acid) uptake and oxidation compared with vehicle treatment. Mitochondrial respiration was assessed by measurement of the OCR (oxygen-consumption rate). 4F increased basal and ATP-linked OCR as well as maximal uncoupled mitochondrial respiration. These changes were associated with a significant increase in ??m (mitochondrial membrane potential). The increase in metabolic activity in 4F-treated MDMs was attenuated by etomoxir, an inhibitor of mitochondrial FA uptake. Finally, addition of the PPAR? antagonist T0070907 to 4F-treated MDMs reduced the expression of CD163 and CD36, cell-surface markers for M2 macrophages, and reduced basal and ATP-linked OCR. These results support our hypothesis that the 4F-mediated differentiation of MDMs to an anti-inflammatory phenotype is due, in part, to an increase in FA uptake and mitochondrial oxidative metabolism. PMID:25742174

  17. 28 CFR 55.5 - Coverage under section 4(f)(4).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 28 Judicial Administration 2 2012-07-01 2012-07-01 false Coverage under section 4(f)(4). 55.5 Section 55.5 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) IMPLEMENTATION OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage 55.5 Coverage under section 4(f)(4). (a) Coverage formula. Section...

  18. Opto-acoustic imaging system for early breast cancer diagnostics: experimental and numerical studies

    NASA Astrophysics Data System (ADS)

    Khokhlova, Tanya D.; Zharinov, Alexei M.; Kozhushko, Viktor V.; Pelivanov, Ivan M.; Karabutov, Alexander A.

    2006-03-01

    Optoacoustic (OA) imaging is based on the generation of thermoelastic stress waves by heating an object in an optically heterogeneous medium with a short laser pulse. The stress waves contain information on the distribution of structures with enhanced optical absorption that can be used for early cancer diagnostics. This technique has already been applied in-vivo for breast cancer diagnostics and yielded higher contrast of obtained images than that of X-ray or ultrasonic images. The resolution was comparable with that yielded by ultrasonic imaging. Therefore, OA imaging is a very promising technique and it is being rapidly developed. Research in the area is now mostly targeted to the development of OA wave detection systems and image reconstruction algorithms. In this work a new design of receiving array transducer, that allows to enhance image resolution is proposed. The array consists of 64 focused piezo-elements made of PVDF slabs imposed on a spherical surface. Resolution yielded by the array in different directions is determined. Several tissue irradiation geometries and laser wavelengths are considered for optimization of the OA image contrast. Obtained results are used for maximum imaging depth studies. All the investigations include both numerical modelling and experiment.

  19. Investigation of a self-sustained volume discharge in c-C4F8

    NASA Astrophysics Data System (ADS)

    Belevtsev, A. A.; Firsov, K. N.; Kazantsev, S. Yu; Kononov, I. G.; Podlesnykh, S. V.

    2015-11-01

    This paper reports the first experimental study of a self-sustained volume discharge (SSVD) in c-C4F8. The discharge voltage and current oscillograms are taken over a wide range of gas pressures. For the first time an SSVD in c-C4F8 preheated by CO2-laser radiation has been investigated. Some special features and temperature-dependent characteristics of this discharge are revealed. There is discussion on the peculiarities of an SSVD in a preirradiated c-C4F8. To refine the static limiting field in c-C4F8 the static dielectric strength of c-C4F8 is measured on changing the gas pressure by nearly two orders of magnitude.

  20. Wavefront modulation and subwavelength diffractive acoustics with an acoustic metasurface.

    PubMed

    Xie, Yangbo; Wang, Wenqi; Chen, Huanyang; Konneker, Adam; Popa, Bogdan-Ioan; Cummer, Steven A

    2014-01-01

    Metasurfaces are a family of novel wavefront-shaping devices with planar profile and subwavelength thickness. Acoustic metasurfaces with ultralow profile yet extraordinary wave manipulating properties would be highly desirable for improving the performance of many acoustic wave-based applications. However, designing acoustic metasurfaces with similar functionality to their electromagnetic counterparts remains challenging with traditional metamaterial design approaches. Here we present a design and realization of an acoustic metasurface based on tapered labyrinthine metamaterials. The demonstrated metasurface can not only steer an acoustic beam as expected from the generalized Snell's law, but also exhibits various unique properties such as conversion from propagating wave to surface mode, extraordinary beam-steering and apparent negative refraction through higher-order diffraction. Such designer acoustic metasurfaces provide a new design methodology for acoustic signal modulation devices and may be useful for applications such as acoustic imaging, beam steering, ultrasound lens design and acoustic surface wave-based applications. PMID:25418084

  1. ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS

    SciTech Connect

    Thurman E. Scott, Jr., Ph.D.; Younane Abousleiman, Ph.D.; Musharraf Zaman, Ph.D., P.E.

    2002-04-30

    Three major goals were accomplished during this phase. First, a study was completed of the effects of stress-induced changes in anisotropic elastic moduli in sandstone. Second, a new method for measuring the anisotropic poroelastic moduli from acoustic data was developed. Third, a series of triaxial experiments were conducted on unconsolidated sands to identify pressure/stress conditions where liquefaction occurs under high confining pressures. Stress-induced changes in anisotropic Young's moduli and shear moduli were observed during deformational pathway experiments. A new method was made for the acquisition of compressional and shear wave velocities along a series of 3-dimensional raypaths through a core sample as it is subjected to deformation. Three different deformational pathway experiments were conducted. During the hydrostatic deformation experiment, little or no anisotropy was observed in either the Young's moduli or shear moduli. Significant deformational anisotropies were observed in both moduli during the uniaxial strain test and the triaxial compression experiment but each had a different nature. During the triaxial experiment the axial and lateral Young's moduli and shear moduli continued to diverge as load was applied. During the uniaxial strain experiment the anisotropy was ''locked in'' early in the loading phase but then remained steady as both the confining pressure and axial stress were applied. A new method for measuring anisotropic Biot's effective stress parameters has also been developed. The method involves measuring the compressional and shear wave velocities in the aforementioned acoustic velocity experiments while varying stress paths. For a stress-induced transversely isotropic medium the acoustic velocity data are utilized to calculate the five independent elastic stiffness components. Once the elastic stiffness components are determined these can be used to calculate the anisotropic Biot's effective stress parameters, {alpha}{sub v} and {alpha}{sub h}, using the equations of Abousleiman et al. (1996). A series of experiments have been conducted, on an initially inherently isotropic Berea sandstone rock sample, to dynamically determine these anisotropic Biot's parameters during deformational pathway experiments. Data acquired during hydrostatic, triaxial, and uniaxial strain pathway experiments indicates that Biot's effective stress parameter changes significantly if the applied stresses are not hydrostatic. Variations, as large as 20% between the axial (vertical) and lateral (horizontal) Biot's effective stress parameters, were observed in some experiments. A series of triaxial compression experiments have been conducted on unconsolidated sand (Oil Creek sand) to determine the pressure/stress conditions which would be favorable for liquefaction. Liquefaction of geopressured sands is thought to be one of the major causative mechanisms of damaging shallow water flows. The experiments were developed to determine if: (1) liquefaction could be made to occur in this particular sand at high confining pressures, and (2) the state of liquefication had the same nature at high pressure conditions typical of shallow water flows as it does in low confining pressure soil mechanics tests. A series of undrained triaxial experiments were successfully used to document that the Oil Creek sand could undergo liquefaction. The nature (i.e., the shape of the deformational pathway in mean pressure/shear stress space) was very similar to those observed in soil mechanics experiments. The undrained triaxial experiments also indicated that this sand would strain soften at relatively high confining pressures--a necessary precursor to liquefaction. These experiments serve as a starting point for a series of acoustic experiments to determine the signature of compressional and shear wave properties as the sand packs approach the state of liquefaction (and shallow water flows).

  2. Comparison of analytical and numerical approaches for CT-based aberration correction in transcranial passive acoustic imaging

    NASA Astrophysics Data System (ADS)

    Jones, Ryan M.; Hynynen, Kullervo

    2016-01-01

    Computed tomography (CT)-based aberration corrections are employed in transcranial ultrasound both for therapy and imaging. In this study, analytical and numerical approaches for calculating aberration corrections based on CT data were compared, with a particular focus on their application to transcranial passive imaging. Two models were investigated: a three-dimensional full-wave numerical model (Connor and Hynynen 2004 IEEE Trans. Biomed. Eng. 51 1693–706) based on the Westervelt equation, and an analytical method (Clement and Hynynen 2002 Ultrasound Med. Biol. 28 617–24) similar to that currently employed by commercial brain therapy systems. Trans-skull time delay corrections calculated from each model were applied to data acquired by a sparse hemispherical (30 cm diameter) receiver array (128 piezoceramic discs: 2.5 mm diameter, 612 kHz center frequency) passively listening through ex vivo human skullcaps (n  =  4) to emissions from a narrow-band, fixed source emitter (1 mm diameter, 516 kHz center frequency). Measurements were taken at various locations within the cranial cavity by moving the source around the field using a three-axis positioning system. Images generated through passive beamforming using CT-based skull corrections were compared with those obtained through an invasive source-based approach, as well as images formed without skull corrections, using the main lobe volume, positional shift, peak sidelobe ratio, and image signal-to-noise ratio as metrics for image quality. For each CT-based model, corrections achieved by allowing for heterogeneous skull acoustical parameters in simulation outperformed the corresponding case where homogeneous parameters were assumed. Of the CT-based methods investigated, the full-wave model provided the best imaging results at the cost of computational complexity. These results highlight the importance of accurately modeling trans-skull propagation when calculating CT-based aberration corrections. Although presented in an imaging context, our results may also be applicable to the problem of transmit focusing through the skull.

  3. Comparison of analytical and numerical approaches for CT-based aberration correction in transcranial passive acoustic imaging.

    PubMed

    Jones, Ryan M; Hynynen, Kullervo

    2016-01-01

    Computed tomography (CT)-based aberration corrections are employed in transcranial ultrasound both for therapy and imaging. In this study, analytical and numerical approaches for calculating aberration corrections based on CT data were compared, with a particular focus on their application to transcranial passive imaging. Two models were investigated: a three-dimensional full-wave numerical model (Connor and Hynynen 2004 IEEE Trans. Biomed. Eng. 51 1693-706) based on the Westervelt equation, and an analytical method (Clement and Hynynen 2002 Ultrasound Med. Biol. 28 617-24) similar to that currently employed by commercial brain therapy systems. Trans-skull time delay corrections calculated from each model were applied to data acquired by a sparse hemispherical (30 cm diameter) receiver array (128 piezoceramic discs: 2.5 mm diameter, 612 kHz center frequency) passively listening through ex vivo human skullcaps (n  =  4) to emissions from a narrow-band, fixed source emitter (1 mm diameter, 516 kHz center frequency). Measurements were taken at various locations within the cranial cavity by moving the source around the field using a three-axis positioning system. Images generated through passive beamforming using CT-based skull corrections were compared with those obtained through an invasive source-based approach, as well as images formed without skull corrections, using the main lobe volume, positional shift, peak sidelobe ratio, and image signal-to-noise ratio as metrics for image quality. For each CT-based model, corrections achieved by allowing for heterogeneous skull acoustical parameters in simulation outperformed the corresponding case where homogeneous parameters were assumed. Of the CT-based methods investigated, the full-wave model provided the best imaging results at the cost of computational complexity. These results highlight the importance of accurately modeling trans-skull propagation when calculating CT-based aberration corrections. Although presented in an imaging context, our results may also be applicable to the problem of transmit focusing through the skull. PMID:26605827

  4. B-Mode and Acoustic Radiation Force Impulse (ARFI) Imaging of Prostate Zonal Anatomy: Comparison with 3T T2-Weighted MR Imaging

    PubMed Central

    Palmeri, Mark L.; Miller, Zachary A.; Glass, Tyler J.; Garcia-Reyes, Kirema; Gupta, Rajan T.; Rosenzweig, Stephen J.; Kauffman, Christopher; Polascik, Thomas J.; Buck, Andrew; Kulbacki, Evan; Madden, John; Lipman, Samantha L.; Rouze, Ned C.; Nightingale, Kathryn R.

    2015-01-01

    Prostate cancer (PCa) is the most common non-cutaneous malignancy among men in the United States and the second leading cause of cancer-related death. Multi-parametric magnetic resonance imaging (mpMRI) has gained recent popularity to characterize PCa. Acoustic Radiation Force Impulse (ARFI) imaging has the potential to aid PCa diagnosis and management by using tissue stiffness to evaluate prostate zonal anatomy and lesions. MR and B-mode/ARFI in vivo imaging datasets were compared with one another and with gross pathology measurements made immediately after radical prostatectomy. Images were manually segmented in 3D Slicer to delineate the central gland (CG) and prostate capsule, and 3D models were rendered to evaluate zonal anatomy dimensions and volumes. Both imaging modalities showed good correlation between estimated organ volume and gross pathologic weights. Ultrasound and MR total prostate volumes were well correlated (R2 = 0.77), but B-mode images yielded prostate volumes that were larger (16.82% ± 22.45%) than MR images, due to overestimation of the lateral dimension (18.4% ± 13.9%), with less significant differences in the other dimensions (7.4% ± 17.6%, anterior-to-posterior, and −10.8% ± 13.9%, apex-to-base). ARFI and MR CG volumes were also well correlated (R2 = 0.85). CG volume differences were attributed to ARFI underestimation of the apex-to-base axis (−28.8% ± 9.4%) and ARFI overestimation of the lateral dimension (21.5% ± 14.3%). B-mode/ARFI imaging yielded prostate volumes and dimensions that were well correlated with MR T2-weighted image (T2WI) estimates, with biases in the lateral dimension due to poor contrast caused by extraprostatic fat. B-mode combined with ARFI imaging is a promising low-cost, portable, real-time modality that can complement mpMRI for PCa diagnosis, treatment planning, and management. PMID:25060914

  5. Vascular characterization of mice with endothelial expression of cytochrome P450 4F2

    PubMed Central

    Cheng, Jennifer; Edin, Matthew L.; Hoopes, Samantha L.; Li, Hong; Bradbury, J. Alyce; Graves, Joan P.; DeGraff, Laura M.; Lih, Fred B.; Garcia, Victor; Shaik, Jafar Sadik B.; Tomer, Kenneth B.; Flake, Gordon P.; Falck, John R.; Lee, Craig R.; Poloyac, Samuel M.; Schwartzman, Michal L.; Zeldin, Darryl C.

    2014-01-01

    Cytochrome P450 (CYP) 4A and 4F enzymes metabolize arachidonic acid to 20-hydroxyeicosatetraenoic acid (20-HETE). Although CYP4A-derived 20-HETE is known to have prohypertensive and proangiogenic properties, the effects of CYP4F-derived metabolites are not well characterized. To investigate the role of CYP4F2 in vascular disease, we generated mice with endothelial expression of human CYP4F2 (Tie2-CYP4F2-Tr). LC/MS/MS analysis revealed 2-foldincreases in 20-HETE levels in tissues and endothelial cells (ECs), relative to wild-type (WT) controls. Tie2-CYP4F2-Tr ECs demonstrated increases in growth (267.133.4 vs. 205.013% at 48 h) and tube formation (7.71.1 vs. 1.60.5 tubes/field) that were 20-HETE dependent and associated with up-regulation of prooxidant NADPH oxidase and proangiogenic VEGF. Increases in VEGF and NADPH oxidase levels were abrogated by inhibitors of NADPH oxidase and MAPK, respectively, suggesting the possibility of crosstalk between pathways. Interestingly, IL-6 levels in Tie2-CYP4F2-Tr mice (18.62.7 vs. 7.92.7 pg/ml) were up-regulated via NADPH oxidase- and 20-HETE-dependent mechanisms. Although Tie2-CYP4F2-Tr aortas displayed increased vasoconstriction, vasorelaxation and blood pressure were unchanged. Our findings indicate that human CYP4F2 significantly increases 20-HETE production, CYP4F2-derived 20-HETE mediates EC proliferation and angiogenesis via VEGF- and NADPH oxidase-dependent manners, and the Tie2-CYP4F2-Tr mouse is a novel model for examining the pathophysiological effects of CYP4F2-derived 20-HETE in the vasculature.Cheng, J., Edin, M. L., Hoopes, S. L., Li, H., Bradbury, J. A., Graves, J. P., DeGraff, L. M., Lih, F. B., Garcia, V., Shaik, J. S. B., Tomer, K. B., Flake, G. P., Falck, J. R., Lee, C. R., Poloyac, S. M., Schwartzman, M. L., Zeldin, D. C. Vascular characterization of mice with endothelial expression of cytochrome P450 4F2. PMID:24668751

  6. Do marine substrates 'look' and 'sound' the same? Supervised classification of multibeam acoustic data using autonomous underwater vehicle images

    NASA Astrophysics Data System (ADS)

    Lucieer, Vanessa; Hill, Nicole A.; Barrett, Neville S.; Nichol, Scott

    2013-01-01

    In this study we outline the techniques used to transform multibeam acoustic data into spatial layers that can be used for predictive habitat modelling. The results allow us to identify multibeam attributes which may act as potential surrogates for environmental variables that influence biodiversity and define which variables may be reliable for predicting the distribution of species in temperate waters. We explore a method for analysing the spatially coincident multibeam bathymetric and backscatter data from shallow coastal waters to generate spatial data products that relate to the classes derived from fine-scale visual imagery obtained using an autonomous underwater vehicle (AUV). Classifications of the multibeam data are performed for substrate, rugosity and sponge cover. Overall classification accuracies for the classes associated with substratum, rugosity and sponge structure were acceptable for biodiversity assessment applications. Accuracies were highest for rugosity classes at 65%, followed by substratum classes at 64% and then sponge structure classes at 57%. Random forest classifiers at a segmentation scale of 30 performed best in classifying substratum and rugosity, while K-nearest neighbour classifiers performed best for sponge structure classes, with no difference in accuracy between scale 30 and 60. Incorporating backscatter variables using segmentation improved the overall accuracy achieved by the best performing model by between 1% (rugosity) and 9% (substratum) above using topographic variables only in the grid-based analyses. Results suggest that image-based backscatter classification show considerable promise for the interpretation of multibeam sonar data for the production of substrate maps. A particular outcome of this research is to provide appropriate and sufficiently fine-scale physical covariates from the multibeam acoustic data to adequately inform models predicting the distribution of biodiversity on benthic reef habitats.

  7. Evaluation of Stiffness of the Spastic Lower Extremity Muscles in Early Spinal Cord Injury by Acoustic Radiation Force Impulse Imaging

    PubMed Central

    Cho, Kang Hee

    2015-01-01

    Objective To investigate intrinsic viscoelastic changes using shear wave velocities (SWVs) of spastic lower extremity muscles in patients with early spinal cord injury (SCI) via acoustic radiation force impulse (ARFI) imaging and to evaluate correlation between the SWV values and spasticity. Methods Eighteen patients with SCI within 3 months and 10 healthy adults participated. We applied the ARFI technique to measure SWV of gastrocnemius muscle (GCM) and long head of biceps femoris muscle. Spasticity of ankle and knee joint was assessed by original Ashworth Scale. Results Ten patients with SCI had spasticity. Patients with spasticity had significantly faster SWV for GCM and biceps femoris muscle than those without spasticity (Mann-Whitney U test, p=0.007 and p=0.008) and normal control (p=0.011 and p=0.037, respectively). The SWV values of GCM correlated with the ankle spasticity (Spearman rank teat, p=0.026). There was significant correlation between the SWV values for long head of biceps femoris muscle and knee spasticity (Spearman rank teat, p=0.022). Conclusion ARFI demonstrated a difference in muscle stiffness in the GCM between patients with spastic SCI and those without spasticity. This finding suggested that stiffness of muscles increased in spastic lower extremity of early SCI patients. ARFI imaging is a valuable tool for noninvasive assessment of the stiffness of the spastic muscle and has the potential to identify pathomechanical changes of the tissue associated with SCI. PMID:26161345

  8. Fiber-delivered Acoustic 3D Imaging System with Laser-induced Breakdown

    NASA Astrophysics Data System (ADS)

    Yasumuro, Yoshihiro; Sugiura, Tadao; Oshiro, Osamu; Chihara, Kunihiro

    This paper describes a fabrication scheme for integrating an optical fiber-delivered catheter for ultrasound (US) imaging. In this catheter, pulsed laser is focused and guided into a tapered optical fiber. The laser passes through the fiber and is refocused to generate laser-induced breakdown (LIB), which emits spherical pulsed US wave. The reflected US waves are received with a hydrophone array to reconstruct 3D images with synthetic aperture method. We examined the probability of LIB generation relative to pulsed energy level for stably producing US pulses and clarified a suitable specification for a laser delivering fiber. Proto-type catheter demonstrated real-time 3D imaging, in which LIB is continuously generated on the tip of the catheter and frontal situation is captured in 3D images in realtime process.

  9. Acoustic Neuroma

    MedlinePLUS

    ... search IRSA's site Unique Hits since January 2003 Acoustic Neuroma Click Here for Acoustic Neuroma Practice Guideline ... to microsurgery. One doctor's story of having an acoustic neuroma In August 1991, Dr. Thomas F. Morgan ...

  10. Apolipoprotein A-I mimetic peptide 4F blocks sphingomyelinase-induced LDL aggregation.

    PubMed

    Nguyen, Su Duy; Javanainen, Matti; Rissanen, Sami; Zhao, Hongxia; Huusko, Jenni; Kivel, Annukka M; Yl-Herttuala, Seppo; Navab, Mohamad; Fogelman, Alan M; Vattulainen, Ilpo; Kovanen, Petri T; rni, Katariina

    2015-06-01

    Lipolytic modification of LDL particles by SMase generates LDL aggregates with a strong affinity for human arterial proteoglycans and may so enhance LDL retention in the arterial wall. Here, we evaluated the effects of apoA-I mimetic peptide 4F on structural and functional properties of the SMase-modified LDL particles. LDL particles with and without 4F were incubated with SMase, after which their aggregation, structure, and proteoglycan binding were analyzed. At a molar ratio of L-4F to apoB-100 of 2.5 to 20:1, 4F dose-dependently inhibited SMase-induced LDL aggregation. At a molar ratio of 20:1, SMase-induced aggregation was fully blocked. Binding of 4F to LDL particles inhibited SMase-induced hydrolysis of LDL by 10% and prevented SMase-induced LDL aggregation. In addition, the binding of the SMase-modified LDL particles to human aortic proteoglycans was dose-dependently inhibited by pretreating LDL with 4F. The 4F stabilized apoB-100 conformation and inhibited SMase-induced conformational changes of apoB-100. Molecular dynamic simulations showed that upon binding to protein-free LDL surface, 4F locally alters membrane order and fluidity and induces structural changes to the lipid layer. Collectively, 4F stabilizes LDL particles by preventing the SMase-induced conformational changes in apoB-100 and so blocks SMase-induced LDL aggregation and the resulting increase in LDL retention. PMID:25861792

  11. Near-infrared absorbing polymer nano-particle as a sensitive contrast agent for photo-acoustic imaging

    NASA Astrophysics Data System (ADS)

    Aoki, Hiroyuki; Nojiri, Mayumi; Mukai, Rieko; Ito, Shinzaburo

    2014-11-01

    Polymer nano-particles (PNPs) with a near-infrared (NIR) light absorption were prepared by the nano-emulsion method to develop contrast agents for photo-acoustic (PA) imaging. The PNP containing silicon naphthalocyanine showed a high absorption coefficient up to 1010 M-1 cm-1. This is comparable to plasmonic gold nano-particles, which have been studied as PA contrast agents. For the PNP larger than 100 nm, the enhancement of the PA signal was observed compared to the gold nano-particle with a similar absorption coefficient and size. In the case of the PNP, the heat by the light absorption is confined in the particle due to the low thermal diffusivity of polymer materials. We showed that the strong thermal confinement effect of PNP results in the enhancement of the efficiency of the PA signal generation and that the PA intensity can be enhanced by the increase of the Grneisen parameter of the matrix polymer of PNP. The PA signal from the PNP of poly(methyl methacrylate) was 9-fold larger than that of gold nano-particles with the same absorption coefficient. We demonstrated that in the in vivo PA imaging the detection limit of PNP was of the order of 10-13 M. The NIR absorbing PNP will be a promising candidate of a sensitive contrast agent for PA imaging.Polymer nano-particles (PNPs) with a near-infrared (NIR) light absorption were prepared by the nano-emulsion method to develop contrast agents for photo-acoustic (PA) imaging. The PNP containing silicon naphthalocyanine showed a high absorption coefficient up to 1010 M-1 cm-1. This is comparable to plasmonic gold nano-particles, which have been studied as PA contrast agents. For the PNP larger than 100 nm, the enhancement of the PA signal was observed compared to the gold nano-particle with a similar absorption coefficient and size. In the case of the PNP, the heat by the light absorption is confined in the particle due to the low thermal diffusivity of polymer materials. We showed that the strong thermal confinement effect of PNP results in the enhancement of the efficiency of the PA signal generation and that the PA intensity can be enhanced by the increase of the Grneisen parameter of the matrix polymer of PNP. The PA signal from the PNP of poly(methyl methacrylate) was 9-fold larger than that of gold nano-particles with the same absorption coefficient. We demonstrated that in the in vivo PA imaging the detection limit of PNP was of the order of 10-13 M. The NIR absorbing PNP will be a promising candidate of a sensitive contrast agent for PA imaging. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04724a

  12. Investigations of electron attachment to the perfluorocarbon molecules c-C4F8, 2-C4F8, 1,3 C4F6, and c-C5F8

    NASA Astrophysics Data System (ADS)

    Feil, Stefan; Mrk, Tilmann D.; Mauracher, Andreas; Scheier, Paul; Mayhew, Chris A.

    2008-11-01

    Non-dissociative and dissociative electron attachment to a series of gas-phase perfluorocarbons (PFCs), namely octafluorocyclobutane, c-C4F8, octafluorobut-2-ene (perfluoro-2-butene), 2-C4F8, hexafluorobuta-1,3-diene (1,3 perfluorobutadiene), 1,3 C4F6, and octafluorocyclopentene (perfluorocyclopentene), c-C5F8, of importance to technological plasmas, have been investigated using two different, but complimentary, instruments available in Innsbruck over the electron energy range 0-20 eV. Anion yields as a function of electron energy have been recorded, with the positions and intensities of the electron attachment resonances being determined. One of these instruments is a double focusing sector field mass spectrometer (VG-ZAB-2SEQ), which has been used for measurements requiring high sensitivity and for obtaining accurate relative anion yields. It has also been used to determine the electron detachment lifetimes of the parent anions under various accelerating voltages, and these results are also presented. The second instrument (CELIA) is a trochoidal electron monochromator coupled to a quadrupole mass filter with a pulse counting system for detecting product anionic species. This provides a much higher energy resolution than the VG-ZAB, which makes it a better instrument to investigate narrow energy resonances close to 0 eV. The results of anion yields, peak positions and the relative intensities presented in this paper are compared with previous data of electron attachment to the above PFCs, including investigations by Professor Eugen Illenberger.

  13. Combined acoustic-photoacoustic and fluorescence imaging catheter for the detection of the atherosclerotic plaque

    NASA Astrophysics Data System (ADS)

    Abran, Maxime; Matteau-Pelletier, Carl; Zerouali-Boukhal, Karim; Tardif, Jean-Claude; Lesage, Frdric

    2011-03-01

    In industrialized countries, cardiovascular diseases remain the main cause of mortality. The detection of atherosclerosis and its associated plaque using imaging techniques allows studying the efficacy of new drugs in vivo. Intravascular ultrasound (IVUS) imaging has been demonstrated to be a powerful tool to uncover structural information of atherosclerotic plaques. Recently, intravascular photoacoustic (IVPA) has been combined with IVUS imaging to add functional and/or molecular information. The IVPA/IVUS combination has been demonstrated in phantoms and ex vivo tissues to provide relevant information about the composition of the plaque, as well as its vulnerability. In this work, we extend previous work by developing a combined IVPA/IVUS system using a rotating ultrasound transducer in a catheter to which an optical fiber is attached. In addition, a third modality was included through fluorescence detection in the same fiber at a distinct wavelength from PA, opening the door to complementary information using fluorescence activatable probes. Cylindrical silicon phantoms with inclusions containing fluorophores or ink were used to validate the system. Bleaching of the fluorophore by the pulsed laser used for photoacoustic was quantified. IVUS images were obtained continuously and used to co-register photoacoustic and fluorescence signals.

  14. Photo-acoustic imaging of blue nanoparticle targeted brain tumor for intra-operative glioma delineation

    NASA Astrophysics Data System (ADS)

    Ray, Aniruddha; Wang, Xueding; Koo Lee, Yong-Eun; Hah, HoeJin; Kim, Gwangseong; Chen, Thomas; Orrienger, Daniel; Sagher, Oren; Kopelman, Raoul

    2011-07-01

    Distinguishing the tumor from the background neo-plastic tissue is challenging for cancer surgery such as surgical resection of glioma. Attempts have been made to use visible or fluorescent markers to delineate the tumors during surgery. However, the systemic injection of the dyes requires high dose, resulting in negative side effects. A novel method to delineate rat brain tumors intra-operatively, as well as post-operatively, using a highly sensitive photoacoustic imaging technique enhanced by tumor targeting blue nanoparticle as contrast agent is demonstrated. The nanoparticles are made of polyacrylamide (PAA) matrix with covalently linked Coomassie-Blue dye. They contain 7.0% dye and the average size is 80nm. Their surface was conjugated with F3 peptide for active tumor targeting. These nanoparticles are nontoxic, chemically inert and have long plasma circulation lifetime, making them suitable as nanodevices for imaging using photoacoustics. Experiments on phantoms and rat brains tumors ex-vivo demonstrate the high sensitivity of photoacoustic imaging in delineating the tumor, containing contrast agent at concentrations too low to be visualized by eye. The control tumors without nanoparticles did not show any enhanced signal. This study shows that photoacoustic imaging facilitated with the nanoparticle contrast agent could contribute to future surgical procedures for glioma.

  15. Development of acoustic model-based iterative reconstruction technique for thick-concrete imaging

    NASA Astrophysics Data System (ADS)

    Almansouri, Hani; Clayton, Dwight; Kisner, Roger; Polsky, Yarom; Bouman, Charles; Santos-Villalobos, Hector

    2016-02-01

    Ultrasound signals have been used extensively for non-destructive evaluation (NDE). However, typical reconstruction techniques, such as the synthetic aperture focusing technique (SAFT), are limited to quasi-homogenous thin media. New ultrasonic systems and reconstruction algorithms are in need for one-sided NDE of non-homogenous thick objects. An application example space is imaging of reinforced concrete structures for commercial nuclear power plants (NPPs). These structures provide important foundation, support, shielding, and containment functions. Identification and management of aging and degradation of concrete structures is fundamental to the proposed long-term operation of NPPs. Another example is geothermal and oil/gas production wells. These multi-layered structures are composed of steel, cement, and several types of soil and rocks. Ultrasound systems with greater penetration range and image quality will allow for better monitoring of the well's health and prediction of high-pressure hydraulic fracturing of the rock. These application challenges need to be addressed with an integrated imaging approach, where the application, hardware, and reconstruction software are highly integrated and optimized. Therefore, we are developing an ultrasonic system with Model-Based Iterative Reconstruction (MBIR) as the image reconstruction backbone. As the first implementation of MBIR for ultrasonic signals, this paper document the first implementation of the algorithm and show reconstruction results for synthetically generated data.1

  16. Development of Acoustic Model-Based Iterative Reconstruction Technique for Thick-Concrete Imaging

    SciTech Connect

    Almansouri, Hani; Clayton, Dwight A; Kisner, Roger A; Polsky, Yarom; Bouman, Charlie; Santos-Villalobos, Hector J

    2015-01-01

    Ultrasound signals have been used extensively for non-destructive evaluation (NDE). However, typical reconstruction techniques, such as the synthetic aperture focusing technique (SAFT), are limited to quasi-homogenous thin media. New ultrasonic systems and reconstruction algorithms are in need for one-sided NDE of non-homogenous thick objects. An application example space is imaging of reinforced concrete structures for commercial nuclear power plants (NPPs). These structures provide important foundation, support, shielding, and containment functions. Identification and management of aging and degradation of concrete structures is fundamental to the proposed long-term operation of NPPs. Another example is geothermal and oil/gas production wells. These multi-layered structures are composed of steel, cement, and several types of soil and rocks. Ultrasound systems with greater penetration range and image quality will allow for better monitoring of the well s health and prediction of high-pressure hydraulic fracturing of the rock. These application challenges need to be addressed with an integrated imaging approach, where the application, hardware, and reconstruction software are highly integrated and optimized. Therefore, we are developing an ultrasonic system with Model-Based Iterative Reconstruction (MBIR) as the image reconstruction backbone. As the first implementation of MBIR for ultrasonic signals, this paper document the first implementation of the algorithm and show reconstruction results for synthetically generated data.

  17. HAER PA,35SCRAN,4F (sheet 1 of 1) Delaware, Lackawanna & ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    HAER PA,35-SCRAN,4-F- (sheet 1 of 1) - Delaware, Lackawanna & Western Railroad, Scranton Yards, Scrap Platform, 350 feet South of South Washington Avenue & River Street, Scranton, Lackawanna County, PA

  18. Characterization of the active site properties of CYP4F12.

    PubMed

    Eksterowicz, John; Rock, Dan A; Rock, Brooke M; Wienkers, Larry C; Foti, Robert S

    2014-10-01

    Cytochrome P450 4F12 is a drug-metabolizing enzyme that is primarily expressed in the liver, kidney, colon, small intestine, and heart. The properties of CYP4F12 that may impart an increased catalytic selectivity (decreased promiscuity) were explored through in vitro metabolite elucidation, kinetic isotope effect experiments, and computational modeling of the CYP4F12 active site. By using astemizole as a probe substrate for CYP4F12 and CYP3A4, it was observed that although CYP4F12 favored astemizole O-demethylation as the primary route of metabolism, CYP3A4 was capable of metabolizing astemizole at multiple sites on the molecule. Deuteration of astemizole at the site of O-demethylation resulted in an isotope effect of 7.1 as well as an 8.3-fold decrease in the rate of clearance for astemizole by CYP4F12. Conversely, although an isotope effect of 3.8 was observed for the formation of the O-desmethyl metabolite when deuterated astemizole was metabolized by CYP3A4, there was no decrease in the clearance of astemizole. Development of a homology model of CYP4F12 based on the crystal structure of cytochrome P450 BM3 predicted an active site volume for CYP4F12 that was approximately 76% of the active site volume of CYP3A4. As predicted, multiple favorable binding orientations were available for astemizole docked into the active site of CYP3A4, but only a single binding orientation with the site of O-demethylation oriented toward the heme was identified for CYP4F12. Overall, it appears that although CYP4F12 may be capable of binding similar ligands to other cytochrome P450 enzymes such as CYP3A4, the ability to achieve catalytically favorable orientations may be inherently more difficult because of the increased steric constraints of the CYP4F12 active site. PMID:25074871

  19. CYP4F18-Deficient Neutrophils Exhibit Increased Chemotaxis to Complement Component C5a

    PubMed Central

    Vaivoda, Rachel; Vaine, Christine; Boerstler, Cassandra; Galloway, Kristy; Christmas, Peter

    2015-01-01

    CYP4Fs were first identified as enzymes that catalyze hydroxylation of leukotriene B4 (LTB4). CYP4F18 has an unusual expression in neutrophils and was predicted to play a role in regulating LTB4-dependent inflammation. We compared chemotaxis of wild-type and Cyp4f18 knockout neutrophils using an in vitro assay. There was no significant difference in the chemotactic response to LTB4, but the response to complement component C5a increased 1.92.25-fold in knockout cells compared to wild-type (P < 0.01). This increase was still observed when neutrophils were treated with inhibitors of eicosanoid synthesis. There were no changes in expression of other CYP4 enzymes in knockout neutrophils that might compensate for loss of CYP4F18 or lead to differences in activity. A mouse model of dextran sodium sulfate colitis was used to investigate the consequences of increased C5a-dependent chemotaxis in vivo, but there was no significant difference in weight loss, disease activity, or colonic tissue myeloperoxidase between wild-type and Cyp4f18 knockout mice. This study demonstrates the limitations of inferring CYP4F function based on an ability to use LTB4 as a substrate, points to expanding roles for CYP4F enzymes in immune regulation, and underscores the in vivo challenges of CYP knockout studies. PMID:26613087

  20. Targeting the eIF4F translation initiation complex: a critical nexus for cancer development.

    PubMed

    Pelletier, Jerry; Graff, Jeremy; Ruggero, Davide; Sonenberg, Nahum

    2015-01-15

    Elevated protein synthesis is an important feature of many cancer cells and often arises as a consequence of increased signaling flux channeled to eukaryotic initiation factor 4F (eIF4F), the key regulator of the mRNA-ribosome recruitment phase of translation initiation. In many cellular and preclinical models of cancer, eIF4F deregulation results in changes in translational efficiency of specific mRNA classes. Importantly, many of these mRNAs code for proteins that potently regulate critical cellular processes, such as cell growth and proliferation, enhanced cell survival and cell migration that ultimately impinge on several hallmarks of cancer, including increased angiogenesis, deregulated growth control, enhanced cellular survival, epithelial-to-mesenchymal transition, invasion, and metastasis. By being positioned as the molecular nexus downstream of key oncogenic signaling pathways (e.g., Ras, PI3K/AKT/TOR, and MYC), eIF4F serves as a direct link between important steps in cancer development and translation initiation. Identification of mRNAs particularly responsive to elevated eIF4F activity that typifies tumorigenesis underscores the critical role of eIF4F in cancer and raises the exciting possibility of developing new-in-class small molecules targeting translation initiation as antineoplastic agents. PMID:25593033

  1. Translation initiation factor eIF4F modifies the dexamethasone response in multiple myeloma

    PubMed Central

    Robert, Francis; Roman, William; Bramoull, Alexandre; Fellmann, Christof; Roulston, Anne; Shustik, Chaim; Porco, John A.; Shore, Gordon C.; Sebag, Michael; Pelletier, Jerry

    2014-01-01

    Enhanced protein synthesis capacity is associated with increased tumor cell survival, proliferation, and resistance to chemotherapy. Cancers like multiple myeloma (MM), which display elevated activity in key translation regulatory nodes, such as the PI3K/mammalian target of rapamycin and MYC-eukaryotic initiation factor (eIF) 4E pathways, are predicted to be particularly sensitive to therapeutic strategies that target this process. To identify novel vulnerabilities in MM, we undertook a focused RNAi screen in which components of the translation apparatus were targeted. Our screen was designed to identify synthetic lethal relationships between translation factors or regulators and dexamethasone (DEX), a corticosteroid used as frontline therapy in this disease. We find that suppression of all three subunits of the eIF4F cap-binding complex synergizes with DEX in MM to induce cell death. Using a suite of small molecules that target various activities of eIF4F, we observed that cell survival and DEX resistance are attenuated upon eIF4F inhibition in MM cell lines and primary human samples. Levels of MYC and myeloid cell leukemia 1, two known eIF4F-responsive transcripts and key survival factors in MM, were reduced upon eIF4F inhibition, and their independent suppression also synergized with DEX. Inhibition of eIF4F in MM exerts pleotropic effects unraveling a unique therapeutic opportunity. PMID:25197055

  2. Bioacoustic systems: insights for acoustical imaging and pattern recognition (Invited Paper)

    NASA Astrophysics Data System (ADS)

    Altes, Richard A.

    1987-09-01

    Standard performance measures and statistical tests must be altered for research on animal sonar. The narrowband range-Doppler ambiguity function must be redefined to analyze wideband signals. A new range, cross-range ambiguity function is needed to represent angle estimation and spatial resolution properties of animal sonar systems. Echoes are transformed into time-frequency (spectrogram-like) representations by the peripheral auditory system. Detection, estimation, and pattern recognition capabilities of animals should thus be analyzed in terms of operations on spectrograms. The methods developed for bioacoustic research yield new insights into the design of man-made imaging and pattern recognition systems. The range, cross-range ambiguity function can be used to improve imaging performance. Important features for echo pattern recognition are illustrated by time-frequency plots showing (i) principal components for spectrograms and (ii) templates for optimum discrimination between data classes.

  3. Acoustic hemostasis

    NASA Astrophysics Data System (ADS)

    Crum, L.; Andrew, M.; Bailey, M.; Beach, K.; Brayman, A.; Curra, F.; Kaczkowski, P.; Kargl, S.; Martin, R.; Vaezy, S.

    2003-04-01

    Over the past several years, the Center for Industrial and Medical Ultrasound (CIMU) at the Applied Physics Laboratory in the University of Washington has undertaken a broad research program in the general area of High Intensity Focused Ultrasound (HIFU). Our principal emphasis has been on the use of HIFU to induce hemostasis; in particular, CIMU has sought to develop a small, lightweight, portable device that would use ultrasound for both imaging and therapy. Such a technology is needed because nearly 50% of combat casualty mortality results from exsanguinations, or uncontrolled bleeding. A similar percentage occurs for civilian death due to trauma. In this general review, a presentation of the general problem will be given, as well as our recent approaches to the development of an image-guided, transcutaneous, acoustic hemostasis device. [Work supported in part by the USAMRMC, ONR and the NIH.

  4. Photoacoustic diagnosis of burns in rats: two-dimensional photo-acoustic imaging of burned tissue

    NASA Astrophysics Data System (ADS)

    Yamazaki, Mutsuo; Sato, Shunichi; Saito, Daizo; Okada, Yoshiaki; Kurita, Akira; Kikuchi, Makoto; Ashida, Hiroshi; Obara, Minoru

    2003-06-01

    We previously reported that for rat burn models, deep dermal burns and deep burns can be well differentiated by measuring the propagation time of the photoacoustic signals originated from the blood in the healthy skin tissue under the damaged tissue layer. However, the diagnosis was based on point measurement in the wound, and therefore site-dependent information on the injuries was not obtained; such information is very important for diagnosis of extended burns. In the present study, we scanned a photoacoustic detector on the wound and constructed two-dimensional (2-D) images of the blood-originated photoacoustic signals for superficial dermal burns (SDB), deep dermal burns (DDB), deep burns (DB), and healthy skins (control) in rats. For each burn model, site-dependent variation of the signal was observed; the variation probably reflects the distribution of blood vessels in the skin tissue. In spite of the variation, clear differentiation was obtained between SDB, DDB, and DB from the 2D images. The images were constructed as a function of post burn time. Temporal signal variation will be also presented.

  5. Very high-resolution seismo-acoustic imaging of seagrass meadows (Mediterranean Sea): Implications for carbon sink estimates

    NASA Astrophysics Data System (ADS)

    Lo Iacono, Claudio; Mateo, Miguel Angel; Grcia, Eullia; Guasch, Lluis; Carbonell, Ramon; Serrano, Laura; Serrano, Oscar; Daobeitia, Juanjo

    2008-09-01

    Posidonia oceanica is a widespread coastal Mediterranean seagrass which accumulates in its subsurface large quantities of organic material derived from its roots, rhizomes and leaf sheaths embedded in sandy sediments. These organic deposits may be up to several meters thick as they accumulate over thousands of years forming the matte, whose high content in organic carbon plays a major role in the global ocean carbon cycle. In this study, very high-resolution seismo-acoustic methods were applied to image the subsurface features of a P. oceanica seagrass meadow at Portlligat (Cadaqus, Girona, Spain), in the NW-Mediterranean Sea. Our findings yield fresh insights into the settling of the P. oceanica meadow in the study area, and define with unprecedented detail the potential volume occupied by the matte. A strong reflector, located from 4.3 to 11.7 m depth, was recognized in several seismo-acoustic profiles as the substratum on which P. oceanica first settled in the study area. A 3D bathymetric model of this substratum allowed us to reconstruct the Portlligat palaeo-environment prior to the settling of P. oceanica, which corresponded to a shallow coastal setting protected from the open sea. A core drilled in the meadow at Portlligat revealed the presence of a 6 m thick dense matte composed of medium to coarse sandy sediments mixed with plant debris and bioclasts. Radiocarbon datings revealed a constant accretion rate of the matte of about 1.1 m/kyr. Gravelly bioclastic deposits observed at the base of the core correspond to the base of the matte and gave a date of 5616 +/- 46 Cal yr BP. For the first time, very high-resolution marine geophysical techniques allowed us to accurately define the volume occupied by P. oceanica matte, which in the study area reaches up to almost 220,000 +/- 17,400 m3. This result is an important step forward in our efforts to estimate the size of the carbon sink represented by P. oceanica meadows along the Mediterranean coasts significantly contributing to the biosphere carbon cycle.

  6. Acoustic performance of mesh compression paddles for a multimodality breast imaging system.

    PubMed

    LeCarpentier, Gerald L; Goodsitt, Mitchell M; Verweij, Sacha; Li, Jie; Padilla, Frederic R; Carson, Paul L

    2014-07-01

    A system incorporating automated 3-D ultrasound and digital X-ray tomosynthesis is being developed for improved breast lesion detection and characterization. The goal of this work is to develop and test candidates for a dual-modality mesh compression paddle. A Computerized Imaging Reference Systems (Norfork, VA, USA) ultrasound phantom with tilted low-contrast cylindrical objects was used. Polyester mesh fabrics (1- and 2-mm spacing), a high-density polyethylene filament grid (Dyneema, DSM Dyneema, Stanley, NC, USA) and a solid polymethylpentene (TPX; Mitsui Plastics, Inc., White Plains, NY) paddle were compared with no overlying structures using a GE Logic 9 with M12L transducer. A viscous gel provided coupling. The phantom was scanned 10 times over 9 cm for each configuration. Image volumes were analyzed for signal strength, contrast and contrast-to-noise ratio. X-ray tests confirmed X-ray transparency for all materials. By all measures, both mesh fabrics outperformed TPX and Dyneema, and there were essentially no differences between 2-mm mesh and unobstructed configurations. PMID:24726203

  7. Enhanced characterization of calcified areas in intravascular ultrasound virtual histology images by quantification of the acoustic shadow: validation against computed tomography coronary angiography.

    PubMed

    Broersen, Alexander; de Graaf, Michiel A; Eggermont, Jeroen; Wolterbeek, Ron; Kitslaar, Pieter H; Dijkstra, Jouke; Bax, Jeroen J; Reiber, Johan H C; Scholte, Arthur J

    2016-04-01

    We enhance intravascular ultrasound virtual histology (VH) tissue characterization by fully automatic quantification of the acoustic shadow behind calcified plaque. VH is unable to characterize atherosclerosis located behind calcifications. In this study, the quantified acoustic shadows are considered calcified to approximate the real dense calcium (DC) plaque volume. In total, 57 patients with 108 coronary lesions were included. A novel post-processing step is applied on the VH images to quantify the acoustic shadow and enhance the VH results. The VH and enhanced VH results are compared to quantitative computed tomography angiography (QTA) plaque characterization as reference standard. The correlation of the plaque types between enhanced VH and QTA differs significantly from the correlation with unenhanced VH. For DC, the correlation improved from 0.733 to 0.818. Instead of an underestimation of DC in VH with a bias of 8.5 mm(3), there was a smaller overestimation of 1.1 mm(3) in the enhanced VH. Although tissue characterization within the acoustic shadow in VH is difficult, the novel algorithm improved the DC tissue characterization. This algorithm contributes to accurate assessment of calcium on VH and could be applied in clinical studies. PMID:26667446

  8. Acoustic Radiation Force Impulse Imaging: A New Tool for the Diagnosis of Papillary Thyroid Microcarcinoma

    PubMed Central

    Zhang, Yi-Feng; Xu, Jun-Mei; Zhang, Jing; Liu, Lin-Na; Xu, Xiao-Hong

    2014-01-01

    Purpose. To evaluate the diagnostic performance of ARFI imaging in differentiating between benign and malignant thyroid nodules <1?cm. Materials and Methods. 173 pathologically proven thyroid nodules (77 benign, 96 malignant) in 157 patients were included in this study. Receiver-operating characteristic curve (ROC) analyses were performed to assess the diagnostic performance of conventional ultrasound (US) and ARFI imaging in papillary thyroid microcarcinoma (PTMC). The independent risk factors for predicting PTMC were evaluated. Results. The mean SWV value of benign and malignant thyroid nodules were 2.57 0.79?m/s (range: 0.904.92?m/s) and 3.88 2.24?m/s (range: 1.499.00?m/s) (P = 0.000). Az for VTI elastography score was higher than that for hypoechoic, absence of halo sign, and type III vascularity (P < 0.05). The optimal cut-offs for VTI elastography score and SWV were score 4 and 3.10?m/s. Gender, hypoechoic, taller than wide, VTI elastography score ? 4, and SWV > 3.10?m/s had been found to be independent risk factors for predicting PTMC. Conclusion. ARFI elastography can provide elasticity information of PTMC quantitatively (VTQ) and directly reflects the overall elastic properties (VTI). Gender, hypoechogenicity, taller than wide, VTI elastography score ? 4, and SWV > 3.10?m/s are independent risk factors for predicting PTMC. ARFI elastography seems to be a new tool for the diagnosis of PTMC. PMID:25045673

  9. Field ionization process of Eu 4f76snp Rydberg states

    NASA Astrophysics Data System (ADS)

    Zhang, Jing; Shen, Li; Dai, Chang-Jian

    2015-11-01

    The field ionization process of the Eu 4f76snp Rydberg states, converging to the first ionization limit, 4f76s 9S4, is systematically investigated. The spectra of the Eu 4f76snp Rydberg states are populated with three-step laser excitation, and detected by electric field ionization (EFI) method. Two different kinds of the EFI pulses are applied after laser excitation to observe the possible impacts on the EFI process. The exact EFI ionization thresholds for the 4f76snp Rydberg states can be determined by observing the corresponding EFI spectra. In particular, some structures above the EFI threshold are found in the EFI spectra, which may be interpreted as the effect from black body radiation (BBR). Finally, the scaling law of the EFI threshold for the Eu 4f76snp Rydberg states with the effective quantum number is built. Project supported by the National Natural Science Foundation of China (Grant Nos. 11004151 and 11174218).

  10. Correlation between CYP4F2 gene rs2108622 polymorphism and susceptibility to ischemic stroke

    PubMed Central

    Meng, Chong; Wang, Juan; Ge, Wei-Ning; Tang, Shao-Can; Xu, Guang-Ming

    2015-01-01

    Objective: To conduct a meta-analysis for the correlation between cytochrome P450 4F2 (CYP4F2) rs2108622 (V433M) gene polymorphism and ischemic stroke. Methods: We retrieved the case-control studies on the correlation between CYP4F2 V433M polymorphism and ischemic stroke included in domestic and international databases before January 2015 and selected the best genetic model, using RevMan 5.2 software for meta-analysis. According to the heterogeneity test results of selected literature, the effect model of consolidated data was selected, and the combined OR and 95% CI were calculated. Results: A total of six documents were included. Recessive model (VM + MM vs. VV) was selected as the best genetic model. The combined results showed that: compared with wild-type VV, there are significant association between ischemic stroke and CYP4F2 polymorphism (OR merge = 1.37, 95% CI: 1.21~1.54, P < 0.001). Conclusion: CYP4F2 V433M may be the susceptibility gene for ischemic stroke. PMID:26629123

  11. Plasma Diagnostic Potential of 2p4f in N+Accurate Wavelengths and Oscillator Strengths

    NASA Astrophysics Data System (ADS)

    Shen, Xiaozhi; Li, Jiguang; Jnsson, Per; Wang, Jianguo

    2015-03-01

    Radiative emission lines from nitrogen and its ions are often observed in nebula spectra, where the N2 + abundance can be inferred from lines of the 2p4f configuration. In addition, intensity ratios between lines of the 2p3p-2p3s and 2p4f-2p3d transition arrays can serve as temperature diagnostics. To aid abundance determinations and plasma diagnostics, wavelengths and oscillator strengths were calculated with high precision for electric dipole (E1) transitions from levels in the 2p4f configuration of N+. Electron correlation and relativistic effects, including the Breit interaction, were systematically taken into account within the framework of the multiconfiguration Dirac-Hartree-Fock method. Except for the 2p4f-2p4d transitions with quite large wavelengths and the two-electron-one-photon 2p4f-2s2p 3 transitions, the uncertainties of the present calculations were controlled to within 3% and 5% for wavelengths and oscillator strengths, respectively. We also compared our results with other theoretical and experimental values when available. Discrepancies were found between our calculations and previous calculations due to the neglect of relativistic effects in the latter.

  12. TARGETING THE eIF4F TRANSLATION INITIATION COMPLEX: A CRITICAL NEXUS FOR CANCER DEVELOPMENT

    PubMed Central

    Pelletier, Jerry; Graff, Jeremy; Ruggero, Davide; Sonenberg, Nahum

    2014-01-01

    Elevated protein synthesis is an important feature of many cancer cells and often arises as a consequence of increased signaling flux channeled to eukaryotic initiation factor (eIF) 4F, the key regulator of the mRNA-ribosome recruitment phase of translation initiation. In many cellular and pre-clinical models of cancer, eIF4F deregulation results in changes in translational efficiency of specific mRNA classes. Importantly, many of these mRNAs code for proteins that potently regulate critical cellular processes such as cell growth and proliferation, enhanced cell survival, and cell migration that ultimately impinge on several hallmarks of cancer, including increased angiogenesis, deregulated growth control, enhanced cellular survival, epithelial-to-mesenchymal transition, invasion and metastasis. By being positioned as the molecular nexus downstream of key oncogenic signaling pathways (e.g. Ras, PI3K/AKT/TOR, and Myc), eIF4F serves as a direct link between important steps in cancer development and translation initiation. Identification of mRNAs particularly responsive to elevated eIF4F activity that typifies tumorigenesis underscores the critical role of eIF4F in cancer and raises the exciting possibility of developing new-in-class small molecules targeting translation initiation as anti-neoplastic agents. PMID:25593033

  13. Evaluating Directional Resolution of Aplanatic Acoustic Lens for Designing Ambient Noise Imaging System

    NASA Astrophysics Data System (ADS)

    Mori, Kazuyoshi; Ogasawara, Hanako; Nakamura, Toshiaki; Sato, Yuji; Tsuchiya, Takenobu; Endoh, Nobuyuki

    2009-07-01

    In our previous studies, it was verified that a spherical biconcave lens with an aperture diameter of 2.0 m has a sufficient directional resolution (e.g., a beam width of 1 at 60 kHz) for realizing an ambient noise imaging (ANI) system. In this study, an aplanatic lens that corrects both spherical and coma aberrations with the same aperture was designed for an ANI system, and its directional resolution was evaluated. First, in order to predict the resolution, we performed a numerical analysis using the finite difference time domain (FDTD) method. Second, the numerical analysis results were verified by a small-scale trial of one-fifth of full size in a water tank. The shapes of the -3 dB areas were similar between the numerical analysis and experimental results at small incidence angles, and the -3 dB areas do not overlap at 1 increments of incidence angle. The resolution of the aplanatic lens was closer to that of an ideal lens than to that of the spherical lens. Finally, it was satisfied that the present lens has sufficient directional resolution for use in an ANI system.

  14. A method of construction of information images of the acoustic signals of the human bronchopulmonary system

    NASA Astrophysics Data System (ADS)

    Bureev, A. Sh.; Zhdanov, D. S.; Zemlyakov, I. Yu.; Kiseleva, E. Yu.; Khokhlova, L. A.

    2015-11-01

    The present study focuses on the development of a method of identification of respiratory sounds and noises of a human naturally and in various pathological conditions. The existing approaches based on a simple method of frequency and time signal analysis, have insufficient specificity, efficiency and unambiguous interpretation of the results of a clinical study. An algorithm for a phase selection of respiratory cycles and analysis of respiratory sounds resulting from bronchi examination of a patient has been suggested. The algorithm is based on the method of phase timing analysis of bronchi phonograms. The results of the phase-frequency algorithm with high resolution reflects a time position of the traceable signals and the individual structure of recorded signals. This allows using the proposed method for the formation of information images (models) of the diagnostically significant fragments. A weight function, frequency parameters of which can be selectively modified, is used for this purpose. The vision of the weighting function is specific to each type of respiratory noise, traditionally referred to quality characteristics (wet or dry noise, crackling, etc.).

  15. Feasibility of High Frequency Acoustic Imaging for Inspection of Containments: Phase II

    SciTech Connect

    Rudzinsky, J.; Bondaryk, J.; Conti, M.

    1999-07-01

    The nuclear power industry is concerned with corrosive thinning of portions of the metallic pressure boundary, particularly in areas that are not directly accessible for inspection. This study investigated the feasibility of detecting these thickness degradations using ultrasonic imaging. A commercial ultrasonic system was used to carry out several full-scale, controlled laboratory experiments. Measurements of 0.5 MHz shear wave levels propagated in 25-mm-thick steel plate embedded in concrete showed 1.4-1.6 dB of signal loss for each centimeter of two-way travel in the steel plate (compared to previous numerical predictions of 3-4 dB), and 1.3 dB of signal loss per centimeter of two-way travel in steel plates embedded in concrete prior to setting of the concrete (i.e., plastic). Negligible losses were measured in plates with a decoupling treatment applied between the steel and concrete to simulate the unbonded portions of the pressure boundary. Scattered signals from straight slots of different size and shape were investigated. The return from a 4-mm-deep rectangular slots exhibited levels 23 dB down relative to incidence and 4-6 dB higher than those obtained from both ''v'' shaped and rounded slots of similar depth. The system displayed an input/output dynamic range of 125 dB and measurement variability less than 1-2dB. Based on these results, a 4-mm-deep, rounded degradation embedded 30 cm in concrete has expected returns of -73dB relative to the input and should therefore be detectable. Results of this and a prior study indicate that the technique has merit and should be developed more fully and demonstrated in the field.

  16. Ocean acoustic reverberation tomography.

    PubMed

    Dunn, Robert A

    2015-12-01

    Seismic wide-angle imaging using ship-towed acoustic sources and networks of ocean bottom seismographs is a common technique for exploring earth structure beneath the oceans. In these studies, the recorded data are dominated by acoustic waves propagating as reverberations in the water column. For surveys with a small receiver spacing (e.g., <10 km), the acoustic wave field densely samples properties of the water column over the width of the receiver array. A method, referred to as ocean acoustic reverberation tomography, is developed that uses the travel times of direct and reflected waves to image ocean acoustic structure. Reverberation tomography offers an alternative approach for determining the structure of the oceans and advancing the understanding of ocean heat content and mixing processes. The technique has the potential for revealing small-scale ocean thermal structure over the entire vertical height of the water column and along long survey profiles or across three-dimensional volumes of the ocean. For realistic experimental geometries and data noise levels, the method can produce images of ocean sound speed on a smaller scale than traditional acoustic tomography. PMID:26723303

  17. Does the 4f-shell contribute to bonding in tetravalent lanthanide halides?

    SciTech Connect

    Ji, Wen-Xin; Xu, Wei; Xiao, Yi; Wang, Shu-Guang

    2014-12-28

    Lanthanide tetrahalide molecules LnX{sub 4} (Ln = Ce, Pr, Tb; X = F, Cl, Br, I) have been investigated by density functional theory at the levels of the relativistic Zero Order Regular Approximation and the relativistic energy-consistent pseudopotentials, using frozen small- and medium-cores. The calculated bond lengths and vibrational frequencies are close to the experimental data. Our calculations indicate 4f shell contributions to bonding in LnX{sub 4}, in particular for the early lanthanides, which show significant overlap between the Ln 4f-shell and the halogen np-shells. The 4f shells contribute to Ln-X bonding in LnX{sub 4} about one third more than in LnX{sub 3}.

  18. ?-Hydroxylation of phylloquinone by CYP4F2 is not increased by ?-tocopherol

    PubMed Central

    Farley, Sherry M.; Leonard, Scott W.; Taylor, Alan W.; Birringer, Marc; Edson, Katheryne Z.; Rettie, Allan E.; Traber, Maret G.

    2013-01-01

    Scope The objective of this study was to investigate the initial catabolic step of vitamin E and K metabolism, the ?-hydroxylation by human cytochrome P450 4F2 (CYP4F2). Methods and Results Tocopherol (T) metabolism was compared using rat liver slices incubated with deuterated (d6)-RRR-?-T (d6-?-T), racemic 2S-?-T (2S, 4RS, 8RS ?-T, 2S-?-T), or d2-?-T (d2-?-T). Following comparable uptake of each T by liver slices, twice as much 13-OH-T was produced from 2S-?-T or d2-?-T (39 15 or 42 5 pmol/g liver, respectively) as from d6-?-T (17 2, p<0.01). Kinetic studies were conducted using insect microsomes expressing human CYP4F2 incubated with d4-phylloquinone (d4-PK), d6-RRR-?-T, d3-SRR-?-T, or d2-?-T. CYP4F2 demonstrated similar apparent maximal velocities (Vmax) when either of the ?-Ts were used as substrates, which were less than the apparent d4-PK Vmax (p<0.0002), while the CYP4F2 catalytic efficiency towards d4-PK (15.8 Vmax/Km) was 5-times greater than for ?-Ts. Vitamin K had no effect on vitamin E catabolism, while vitamin E slightly decreased the d4-PK Vmax. Conclusions CYP4F2 discriminates between Ts and PK in vitro, but ?-T does not apparently increase PK ?-hydroxylation by this mechanism. PMID:23650179

  19. Comparison of deconvolution methods for the visualization of acoustic sources based on cross-spectral imaging function beamforming

    NASA Astrophysics Data System (ADS)

    Chu, Zhigang; Yang, Yang

    2014-10-01

    DAMAS, DAMAS2, NNLS, Fourier-based NNLS, CLEAN and CLEAN-SC are typical deconvolution methods, which have been used in the visualization of acoustic sources based on beamforming to improve the spatial resolution and the dynamic range effectively. It is of great significance to demonstrate and compare properties of these methods comprehensively. In this paper, these methods are applied to cross-spectral imaging function (CSIF) beamforming with auto-spectra exclusion and their properties are demonstrated and compared with each other first by computational simulations consisting of a single source, two incoherent sources and two coherent sources. All the deconvolution methods can visualize single source or incoherent sources in the region where the assumption of shift invariant point spread function is valid accurately and clearly. Not only the spatial resolution is improved dramatically, but also the sidelobes are eliminated effectively. In addition, these methods rank in a diminishing sequence of sidelobe elimination ability from CLEAN-SC, CLEAN, DAMAS, Fourier-based NNLS, NNLS to DAMAS2. When the sources are out of the valid region, only DAMAS, NNLS, CLEAN and CLEAN-SC succeed in visualizing the sources and CLEAN-SC and CLEAN acquire the cleanest source images, then DAMAS, finally NNLS, while DAMAS2 and Fourier-based NNLS fail to not only locate the sources but also capture the strengths. DAMAS, DAMAS2, NNLS and Fourier-based NNLS have good availability for coherent sources in the valid region. In contrast, CLEAN fails to remove sidelobes effectively and CLEAN-SC can only detect one source. DAMAS2 and Fourier-based NNLS also perform poorly for coherent sources out of the valid region. Additionally, DAMAS2 and Fourier-based NNLS consume a minimum of time to conduct a calculation, CLEAN and CLEAN-SC take the second place, whereas DAMAS and NNLS are the slowest. Then a series of experiments are performed on small loudspeakers to validate simulations and compare robustness of these deconvolution methods in practical applications. Some practical factors such as the frequency response characteristic mismatch among the measurement devices have almost no influence on the results of CLEAN-SC, bring some change to the results of DAMAS, DAMAS2, NNLS and Fourier-based NNLS in terms of reconstructed maximum values, sidelobes, etc., and contribute plenty of extra sidelobe contaminations to the results of CLEAN. The conclusions play a guiding significance on the application of these deconvolution methods in practical engineering.

  20. Auger decay paths of mercury 5 p and 4 f vacancies revealed by multielectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Palaudoux, J.; Huttula, S.-M.; Huttula, M.; Penent, F.; Andric, L.; Lablanquie, P.

    2015-01-01

    Single and double Auger processes following ionization of 4 f and 5 p inner shells have been studied using multielectron coincidence spectroscopy. Coincidence technique enables us to resolve state by state all single and double Auger paths with a resolution better than the lifetime broadening. Drastic step-to-step decay lifetime changes are observed and reported as Coster-Kronig transition takes place either in the first (5 p ) or in the second (4 f ) step of the Auger cascade. Relativistic ab initio theory has been used to predict and interpret the experimental observations.

  1. Regulation of Pou4f3 Gene Expression in Hair Cells by 5 DNA in Mice

    PubMed Central

    Masuda, Masatsugu; Dulon, Didier; Pak, Kwang; Mullen, Lina M.; Li, Yan; Erkman, Linda; Ryan, Allen F.

    2011-01-01

    The POU-domain transcription POU4F3 is expressed in the sensory cells of the inner ear. Expression begins shortly after commitment to the hair cell (HC) fate, and continues throughout life. It is required for terminal HC differentiation and survival. To explore regulation of the murine Pou4f3 gene, we linked enhanced green fluorescent protein (eGFP) to 8.5 kb of genomic sequence 5 to the start codon in transgenic mice. eGFP was uniformly present in all embryonic and neonatal HCs. Expression of eGFP was also observed in developing Merkel cells and olfactory neurons as well as adult inner and vestibular HCs, mimicking the normal expression pattern of POU4F3 protein, with the exception of adult outer HCs. Apparently ectopic expression was observed in developing inner ear neurons. On a Pou4f3 null background, the transgene produced expression in embryonic HCs which faded soon after birth both in vivo and in vitro. Pou4f3 null HCs treated with caspase 3 and 9 inhibitors survived longer than untreated HCs, but still showed reduced expression of eGFP. The results suggest the existence of separate enhancers for different HC types, as well as strong autoregulation of the Pou4f3 gene. Bioinformatic analysis of four divergent mammalian species revealed three highly-conserved regions within the transgene: 400 bp immediately 5 to the Pou4f3 ATG, a short sequence at -1.3 kb, and a longer region at -8.2 to -8.5 kb. The latter contained E-box motifs that bind bHLH transcription factors, including motifs activated by ATOH1. Co-transfection of HEK293 or VOT-E36 cells with ATOH1 and the transgene as a reporter enhanced eGFP expression when compared to the transgene alone. Chromatin immunoprecipitation of the three highly conserved regions revealed binding of ATOH1 to the distal-most conserved region. The results are consistent with regulation of Pou4f3 in HCs by ATOH1 at a distal enhancer. PMID:21958861

  2. Kondo physics in a rare earth ion with well localized 4f electrons.

    PubMed

    Stankiewicz, Jolanta; Evangelisti, Marco; Fisk, Zachary; Schlottmann, Pedro; Gor'kov, Lev P

    2012-06-22

    Dilute Nd in simple cubic LaB(6) shows electrical resistance and specific heat features at low temperature consistent with a Kondo scale of T(K) 4f(3) J = 9/2 Hund's rule configuration which is not anticipated to be Kondo coupled to the conduction electrons in LaB(6). We conjecture that the unexpected Kondo effect arises via participation of 4f quadrupolar degrees of freedom of the Nd crystal-field, ground-state quartet. PMID:23004647

  3. Acoustic Neuroma

    MedlinePLUS

    An acoustic neuroma is a benign tumor that develops on the nerve that connects the ear to the brain. ... can press against the brain, becoming life-threatening. Acoustic neuroma can be difficult to diagnose, because the ...

  4. Contribution of the 4 f -core-excited states in determination of atomic properties in the Promethium Isoelectronic Sequence

    NASA Astrophysics Data System (ADS)

    Beiersdorfer, Peter; Safronova, U. I.; Safronova, A. S.

    2014-05-01

    The atomic properties of Pm-like ions were comprehensively studied using relativistic atomic codes with the main emphasis on W ion. Excitation energies of the 4f14 nl (with nl = 5 s , 6 s , 5 p , 6 p , 5 d , 6 d , and 5 f) states in Pm-like ions with nuclear charge Z ranging from 74 to 100 are evaluated within the framework of relativistic many-body theory (RMBPT). First- and second-order Coulomb energies and first- and second-order Breit corrections to the energies are calculated. The important question of what is the ground state in Pm-like ions was answered. Properties of the 4 f -core-excited states are evaluated using the multiconfiguration relativistic Hebrew University Lawrence Livermore Atomic Code (HULLAC code) and the Hartree-Fock-Relativistic method (COWAN code). Our large scale calculations includes the following set of configurations: 4f14 5 s , 4f14 5 p , 4f13 5s2 , 4f13 5p2 , 4f13 5 s 5 p , 4f12 5s2 5 p , 4f12 5 s 5p2 , and 4f12 5p3 . Excitation energies, transition rates, and lifetimes in Pm-like tungsten are evaluated with additional inclusion of the 4f11 5s2 5p2 , 4f11 5 s 5p3 , 4f10 5s2 5p3 , and 4f10 5 s 5p4 configurations. Wavelengths of the 5 s - 5 p transitions are obtained by the COWAN, HULLAC, and RMBPT codes. This research was sponsored by DOE under the OFES grant DE-FG02-08ER54951 and in part by NNSA Cooperative Agreement DE-NA0001984. Work at Lawrence Livermore National Lab. was performed under the auspices of DOE under Contract DE-AC52-07NA27344.

  5. Substituting mouse transcription factor Pou4f2 with a sea urchin orthologue restores retinal ganglion cell development.

    PubMed

    Mao, Chai-An; Agca, Cavit; Mocko-Strand, Julie A; Wang, Jing; Ullrich-Lüter, Esther; Pan, Ping; Wang, Steven W; Arnone, Maria Ina; Frishman, Laura J; Klein, William H

    2016-03-16

    Pou domain transcription factor Pou4f2 is essential for the development of retinal ganglion cells (RGCs) in the vertebrate retina. A distant orthologue of Pou4f2 exists in the genome of the sea urchin (class Echinoidea) Strongylocentrotus purpuratus (SpPou4f1/2), yet the photosensory structure of sea urchins is strikingly different from that of the mammalian retina. Sea urchins have no obvious eyes, but have photoreceptors clustered around their tube feet disc. The mechanisms that are associated with the development and function of photoreception in sea urchins are largely unexplored. As an initial approach to better understand the sea urchin photosensory structure and relate it to the mammalian retina, we asked whether SpPou4f1/2 could support RGC development in the absence of Pou4f2. To answer this question, we replaced genomic Pou4f2 with an SpPou4f1/2 cDNA. In Pou4f2-null mice, retinas expressing SpPou4f1/2 were outwardly identical to those of wild-type mice. SpPou4f1/2 retinas exhibited dark-adapted electroretinogram scotopic threshold responses, indicating functionally active RGCs. During retinal development, SpPou4f1/2 activated RGC-specific genes and in S. purpuratus, SpPou4f2 was expressed in photoreceptor cells of tube feet in a pattern distinct from Opsin4 and Pax6. Our results suggest that SpPou4f1/2 and Pou4f2 share conserved components of a gene network for photosensory development and they maintain their conserved intrinsic functions despite vast morphological differences in mouse and sea urchin photosensory structures. PMID:26962139

  6. Acoustic Seal

    NASA Technical Reports Server (NTRS)

    Steinetz, Bruce M. (Inventor)

    2006-01-01

    The invention relates to a sealing device having an acoustic resonator. The acoustic resonator is adapted to create acoustic waveforms to generate a sealing pressure barrier blocking fluid flow from a high pressure area to a lower pressure area. The sealing device permits noncontacting sealing operation. The sealing device may include a resonant-macrosonic-synthesis (RMS) resonator.

  7. Acoustic seal

    NASA Technical Reports Server (NTRS)

    Steinetz, Bruce M. (Inventor)

    2006-01-01

    The invention relates to a sealing device having an acoustic resonator. The acoustic resonator is adapted to create acoustic waveforms to generate a sealing pressure barrier blocking fluid flow from a high pressure area to a lower pressure area. The sealing device permits noncontacting sealing operation. The sealing device may include a resonant-macrosonic-synthesis (RMS) resonator.

  8. Evaluating the Feasibility of Acoustic Radiation Force Impulse Shear Wave Elasticity Imaging of the Uterine Cervix With an Intracavity Array: A Simulation Study

    PubMed Central

    Feltovich, Helen; Homyk, Andrew D.; Carlson, Lindsey C.; Hall, Timothy J.

    2015-01-01

    The uterine cervix softens, shortens, and dilates throughout pregnancy in response to progressive disorganization of its layered collagen microstructure. This process is an essential part of normal pregnancy, but premature changes are associated with preterm birth. Clinically, there are no reliable noninvasive methods to objectively measure cervical softening or assess cervical microstructure. The goal of these preliminary studies was to evaluate the feasibility of using an intracavity ultrasound array to generate acoustic radiation force impulse (ARFI) excitations in the uterine cervix through simulation, and to optimize the acoustic radiation force (ARF) excitation for shear wave elasticity imaging (SWEI) of the tissue stiffness. The cervix is a unique soft tissue target for SWEI because it has significantly greater acoustic attenuation (? = 1.3 to 2.0 dBcm?1MHz?1) than other soft tissues, and the pathology being studied tends to lead to an increase in tissue compliance, with healthy cervix being relatively stiff compared with other soft tissues (E ? 25 kPa). Additionally, the cervix can only be accessed in vivo using a transvaginal or catheter-based array, which places additional constraints on the excitation focal characteristics that can be used during SWEI. Finite element method (FEM) models of SWEI show that larger-aperture, catheter-based arrays can utilize excitation frequencies up to 7 MHz to generate adequate focal gain up to focal depths 10 to 15 mm deep, with higher frequencies suffering from excessive amounts of near-field acoustic attenuation. Using full-aperture excitations can yield ~40% increases in ARFI-induced displacements, but also restricts the depth of field of the excitation to ~0.5 mm, compared with 2 to 6 mm, which limits the range that can be used for shear wave characterization of the tissue. The center-frequency content of the shear wave particle velocity profiles ranges from 1.5 to 2.5 kHz, depending on the focal configuration and the stiffness of the material being imaged. Overall, SWEI is possible using catheter-based imaging arrays to generate adequate displacements in cervical tissue for shear wave imaging, although specific considerations must be made when optimizing these arrays for this shear wave imaging application. PMID:24081254

  9. Synthesis and spectral investigations of Mn(II) ions doped NaCaAlPO4F3 phosphor

    NASA Astrophysics Data System (ADS)

    Pushpa Manjari, V.; Rama Krishna, Ch.; Muntaz Begum, Sk.; Ravikumar, R. V. S. S. N.

    2014-01-01

    Mn(II) ions doped NaCaAlPO4F3 phosphor was synthesized by using solid state reaction method. The prepared sample was characterized by various spectroscopic techniques such as powder XRD, SEM with EDS, Optical absorption, electron paramagnetic resonance (EPR) and photoluminescence. From powder XRD, the average crystallite size was calculated about 46 nm. SEM images showed the irregular shaped entities present in the sample. Optical absorption spectrum gave the absorption bands in UV-VIS region which are the characteristic of Mn(II) ions in octahedral symmetry. The room temperature EPR spectrum exhibited a six weak hyperfine splitting lines centered at g = 2.0. Photoluminescence spectrum showed the emission peaks in visible region, from yellow to red with an excitation wavelength of 465 nm. From the emission spectral data, the CIE chromaticity coordinates were also calculated as (x = 0.661, y = 0.338).

  10. Infrared imaging and acoustic sizing of a bubble inside a micro-electro-mechanical system piezo ink channel

    NASA Astrophysics Data System (ADS)

    van der Bos, Arjan; Segers, Tim; Jeurissen, Roger; van den Berg, Marc; Reinten, Hans; Wijshoff, Herman; Versluis, Michel; Lohse, Detlef

    2011-08-01

    Piezo drop-on-demand inkjet printers are used in an increasing number of applications because of their reliable deposition of droplets onto a substrate. Droplets of a few picoliters are ejected from an inkjet nozzle at frequencies of up to 100 kHz. However, the entrapment of an air microbubble in the ink channel can severely impede the productivity and reliability of the printing system. The air bubble disturbs the channel acoustics, resulting in disrupted drop formation or failure of the jetting process. Here we study a micro-electro-mechanical systems-based printhead. By using the actuating piezo transducer in receive mode, the acoustical field inside the channel was monitored, clearly identifying the presence of an air microbubble inside the channel during failure of the jetting process. The infrared visualization technique allowed for the accurate sizing of the bubble, including its dynamics, inside the intact printhead. A model was developed to calculate the mutual interaction between the channel acoustics and the bubble dynamics. The model was validated by simultaneous acoustical and infrared detection of the bubble. The model can predict the presence and size of entrapped air bubbles inside an operating ink channel purely from the acoustic response.

  11. 28 CFR 55.5 - Coverage under section 4(f)(4).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 28 Judicial Administration 2 2013-07-01 2013-07-01 false Coverage under section 4(f)(4). 55.5 Section 55.5 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) IMPLEMENTATION OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage § 55.5 Coverage...

  12. 48 CFR 47.303-4 - F.o.b. origin, freight prepaid.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false F.o.b. origin, freight... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-4 F.o.b. origin, freight prepaid. (a) Explanation of delivery term. F.o.b. origin, freight prepaid means— (1) Free of expense...

  13. 48 CFR 47.303-4 - F.o.b. origin, freight prepaid.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 1 2013-10-01 2013-10-01 false F.o.b. origin, freight... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-4 F.o.b. origin, freight prepaid. (a) Explanation of delivery term. F.o.b. origin, freight prepaid means— (1) Free of expense...

  14. 48 CFR 47.303-4 - F.o.b. origin, freight prepaid.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 1 2012-10-01 2012-10-01 false F.o.b. origin, freight... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-4 F.o.b. origin, freight prepaid. (a) Explanation of delivery term. F.o.b. origin, freight prepaid means— (1) Free of expense...

  15. 48 CFR 47.303-4 - F.o.b. origin, freight prepaid.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 1 2014-10-01 2014-10-01 false F.o.b. origin, freight... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-4 F.o.b. origin, freight prepaid. (a) Explanation of delivery term. F.o.b. origin, freight prepaid means— (1) Free of expense...

  16. 48 CFR 47.303-4 - F.o.b. origin, freight prepaid.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 1 2011-10-01 2011-10-01 false F.o.b. origin, freight... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-4 F.o.b. origin, freight prepaid. (a) Explanation of delivery term. F.o.b. origin, freight prepaid means— (1) Free of expense...

  17. Bulk plasma fragmentation in a C4F8 inductively coupled plasma: A hybrid modeling study

    NASA Astrophysics Data System (ADS)

    Zhao, Shu-Xia; Zhang, Yu-Ru; Gao, Fei; Wang, You-Nian; Bogaerts, Annemie

    2015-06-01

    A hybrid model is used to investigate the fragmentation of C4F8 inductive discharges. Indeed, the resulting reactive species are crucial for the optimization of the Si-based etching process, since they determine the mechanisms of fluorination, polymerization, and sputtering. In this paper, we present the dissociation degree, the density ratio of F vs. CxFy (i.e., fluorocarbon (fc) neutrals), the neutral vs. positive ion density ratio, details on the neutral and ion components, and fractions of various fc neutrals (or ions) in the total fc neutral (or ion) density in a C4F8 inductively coupled plasma source, as well as the effect of pressure and power on these results. To analyze the fragmentation behavior, the electron density and temperature and electron energy probability function (EEPF) are investigated. Moreover, the main electron-impact generation sources for all considered neutrals and ions are determined from the complicated C4F8 reaction set used in the model. The C4F8 plasma fragmentation is explained, taking into account many factors, such as the EEPF characteristics, the dominance of primary and secondary processes, and the thresholds of dissociation and ionization. The simulation results are compared with experiments from literature, and reasonable agreement is obtained. Some discrepancies are observed, which can probably be attributed to the simplified polymer surface kinetics assumed in the model.

  18. 28 CFR 55.5 - Coverage under section 4(f)(4).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Coverage under section 4(f)(4). 55.5 Section 55.5 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) IMPLEMENTATION OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage 55.5 Coverage...

  19. Late-onset Charcot-Marie-Tooth disease 4F caused by periaxin gene mutation.

    PubMed

    Tokunaga, Shoko; Hashiguchi, Akihiro; Yoshimura, Akiko; Maeda, Kengo; Suzuki, Takashi; Haruki, Hiroyo; Nakamura, Tomonori; Okamoto, Yuji; Takashima, Hiroshi

    2012-11-01

    We identified the main features of Charcot-Marie-Tooth (CMT) disease, type 4F, caused by a periaxin gene (PRX) mutation in Japanese patients. Periaxin is known as one of the key myelination molecules, forming tight junction between myelin loop and axon. We collected 427 DNA samples from individuals with CMT or CMT-related neuropathy, negative for PMP22 duplication. We investigated PRX mutations using a purpose-built resequencing array screen during the period 2006-2012. We detected two types of PRX mutations in three patients; one patient showed a novel homozygous p.D651N mutation and the other two showed homozygous p.R1070X mutation. All PRX mutations reported so far have been of nonsense or frameshift type. In this study, we found homozygous missense mutation p.D651N. Aspartate 651 is located in a repeat domain; its position might indicate an important function. PRX mutations usually lead to early-onset, autosomal-recessive demyelinating CMT neuropathy 4F (CMT4F) or Dejerine-Sottas disease; their clinical phenotypes are severe. In our three patients, the onset of the disease was at the age of 27 years or later, and their clinical phenotypes were milder compared with those reported in previous studies. We showed a variation of clinical phenotypes for CMT4F caused by a novel, nonsense PRX mutation. PMID:22847150

  20. Absorption intensity analysis of the Er3+(4f11) transitions in calcium fluorophosphate

    NASA Astrophysics Data System (ADS)

    Coeckelenbergh, Cody H.; Yow, Raylon M.; Russell, Charles C., III; Sardar, Dhiraj K.

    2004-10-01

    A spectroscopic analysis is performed on Er3+(4f11) ions doped in calcium fluorophosphate (FAP) in order to assess this material for its potential as a near infrared laser material. The Judd-Ofelt model is applied to the polarization-dependant room temperature absorbtion intensities of Er3+(4f11) in FAP in order to obtain the three phenomenological intensity parameters. The intensity parameters are used to determine the radiative decay rates (emission probabilities), radiative lifetimes, and branching ratios of the Er3+ transitions from the upper multiplet manifolds to the corresponding lower-lying multiplet manifolds 2S+lLJ of Er3+(4f11) in FAP. Using the radiative decay rates of the Er3+(4f11) transitions between the corresponding excited states and the lower-lying states, the radiative lifetimes of eight excited states are determined in this host. Using room temperature fluorescence lifetime and the radiative lifetime of the Er3+ 4I13/2 Dot; 4I15/2 (1.52 ?m)transition, the quantum efficiency is also determined.

  1. 28 CFR 55.8 - Relationship between section 4(f)(4) and section 203(c).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage 55... 4(f)(4) and section 203(c) regarding minority language material and assistance are essentially... not have the effect of terminating coverage under the other provision....

  2. 28 CFR 55.8 - Relationship between section 4(f)(4) and section 203(c).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Relationship between section 4(f)(4) and section 203(c). 55.8 Section 55.8 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) IMPLEMENTATION OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage 55.8 Relationship between section...

  3. 28 CFR 55.8 - Relationship between section 4(f)(4) and section 203(c).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage 55... 4(f)(4) and section 203(c) regarding minority language material and assistance are essentially... provision would not have the effect of terminating coverage under the other provision....

  4. 28 CFR 55.8 - Relationship between section 4(f)(4) and section 203(c).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage 55... 4(f)(4) and section 203(c) regarding minority language material and assistance are essentially... not have the effect of terminating coverage under the other provision....

  5. 28 CFR 55.8 - Relationship between section 4(f)(4) and section 203(c).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage 55... 4(f)(4) and section 203(c) regarding minority language material and assistance are essentially... not have the effect of terminating coverage under the other provision....

  6. 28 CFR 55.5 - Coverage under section 4(f)(4).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 28 Judicial Administration 2 2014-07-01 2014-07-01 false Coverage under section 4(f)(4). 55.5 Section 55.5 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) IMPLEMENTATION OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage 55.5 Coverage...

  7. 28 CFR 55.5 - Coverage under section 4(f)(4).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 28 Judicial Administration 2 2011-07-01 2011-07-01 false Coverage under section 4(f)(4). 55.5 Section 55.5 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) IMPLEMENTATION OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage 55.5 Coverage...

  8. Multi-cations doped LiVPO4F cathode for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Sun, Xiaofei; Xu, Youlong; Teng, Feng; Sun, Gongyu; Chen, Yanjun; Chen, Guogang

    2015-05-01

    The multi-cations doped LiVPO4F, nominally Li0.97Cr0.01V0.95Al0.01Nb0.02PO4F0.97, is prepared by Chromium (Cr) doping on lithium site and Al-Nb co-doping on vanadium site via a conventional carbothermal reduction (CTR) route. The crystallographic lattice volume, particle size and morphology are not obviously changed comparing with un-doped LiVPO4F. However, the high rate and lifetime cycling performances are noticeably improved although the capacities at very low currents are slightly decreased. The reversible capacity at 1/10 C, 1 C, 2 C and 4 C of the pristine LiVPO4F is 143 mA h g-1, 99 mA h g-1, 86 mA h g-1 and 70 mA h g-1, respectively, while that of the doped counterpart is 138 mA h g-1, 102 mA h g-1, 95 mA h g-1 and 82 mA h g-1, respectively. The capacity retention after 100 galvanostatic cycles at 1.5 C is enhanced from 85.4% to 90.9% by such multi-cations doping. Moreover, the initial coulombic efficiency is significantly increased from 81.8% to 90.3% as well.

  9. Atomic origin of 3d(9)4?f(1) configuration in La(3+) solids.

    PubMed

    Yu, S-W; Carpenter, M H; Ponce, F; Friedrich, S; Lee, J-S

    2015-10-14

    We have studied the excited electronic structure of LaBr3(Ce) scintillator by soft x-ray spectroscopy such as x-ray absorption spectroscopy (XAS) and x-ray emission spectroscopy (XES). The La 3d XAS and XES spectra of LaBr3(Ce) are compared with those of other La(3+)?solids (LaF3, La2O3, and La metal). From this comparison, it turns out that the La 3d XAS and XES spectra from all the La(3+) solids considered here appear at almost the same energy, even though the corresponding binding energies of the 3d core holes determined by XPS (x-ray photoelectron spectroscopy) are very different. As a result, we argue that the atomic nature of the 3d?4f configuration created by 3d?4f? ? 3d?4f x-ray absorption process in La(3+) solids is maintained via the localized 4?f?(1) state, which screens the 3d core holes differently from one La(3+) solid to another. PMID:26401640

  10. Acoustic emission linear pulse holography

    DOEpatents

    Collins, H.D.; Busse, L.J.; Lemon, D.K.

    1983-10-25

    This device relates to the concept of and means for performing Acoustic Emission Linear Pulse Holography, which combines the advantages of linear holographic imaging and Acoustic Emission into a single non-destructive inspection system. This unique system produces a chronological, linear holographic image of a flaw by utilizing the acoustic energy emitted during crack growth. The innovation is the concept of utilizing the crack-generated acoustic emission energy to generate a chronological series of images of a growing crack by applying linear, pulse holographic processing to the acoustic emission data. The process is implemented by placing on a structure an array of piezoelectric sensors (typically 16 or 32 of them) near the defect location. A reference sensor is placed between the defect and the array.

  11. Broadband Acoustic Hyperbolic Metamaterial.

    PubMed

    Shen, Chen; Xie, Yangbo; Sui, Ni; Wang, Wenqi; Cummer, Steven A; Jing, Yun

    2015-12-18

    In this Letter, we report on the design and experimental characterization of a broadband acoustic hyperbolic metamaterial. The proposed metamaterial consists of multiple arrays of clamped thin plates facing the y direction and is shown to yield opposite signs of effective density in the x and y directions below a certain cutoff frequency, therefore, yielding a hyperbolic dispersion. Partial focusing and subwavelength imaging are experimentally demonstrated at frequencies between 1.0 and 2.5 kHz. The proposed metamaterial could open up new possibilities for acoustic wave manipulation and may find usage in medical imaging and nondestructive testing. PMID:26722924

  12. Broadband Acoustic Hyperbolic Metamaterial

    NASA Astrophysics Data System (ADS)

    Shen, Chen; Xie, Yangbo; Sui, Ni; Wang, Wenqi; Cummer, Steven A.; Jing, Yun

    2015-12-01

    In this Letter, we report on the design and experimental characterization of a broadband acoustic hyperbolic metamaterial. The proposed metamaterial consists of multiple arrays of clamped thin plates facing the y direction and is shown to yield opposite signs of effective density in the x and y directions below a certain cutoff frequency, therefore, yielding a hyperbolic dispersion. Partial focusing and subwavelength imaging are experimentally demonstrated at frequencies between 1.0 and 2.5 kHz. The proposed metamaterial could open up new possibilities for acoustic wave manipulation and may find usage in medical imaging and nondestructive testing.

  13. Evaluating the Acoustic Effect of Over-the-Rotor Foam-Metal Liner Installed on a Low Speed Fan Using Virtual Rotating Microphone Imaging

    NASA Technical Reports Server (NTRS)

    Sutliff, Daniel L.; Dougherty, Robert P.; Walker, Bruce E.

    2010-01-01

    An in-duct beamforming technique for imaging rotating broadband fan sources has been used to evaluate the acoustic characteristics of a Foam-Metal Liner installed over-the-rotor of a low-speed fan. The NASA Glenn Research Center s Advanced Noise Control Fan was used as a test bed. A duct wall-mounted phased array consisting of several rings of microphones was employed. The data are mathematically resampled in the fan rotating reference frame and subsequently used in a conventional beamforming technique. The steering vectors for the beamforming technique are derived from annular duct modes, so that effects of reflections from the duct walls are reduced.

  14. Imaging and quantitative data acquisition of biological cell walls with Atomic Force Microscopy and Scanning Acoustic Microscopy

    SciTech Connect

    Tittmann, B. R.; Xi, X.

    2014-09-01

    This chapter demonstrates the feasibility of Atomic Force Microscopy (AFM) and High Frequency Scanning Acoustic Microscopy (HF-SAM) as tools to characterize biological tissues. Both the AFM and the SAM have shown to provide imaging (with different resolution) and quantitative elasticity measuring abilities. Plant cell walls with minimal disturbance and under conditions of their native state have been examined with these two kinds of microscopy. After descriptions of both the SAM and AFM, their special features and the typical sample preparation is discussed. The sample preparation is focused here on epidermal peels of onion scales and celery epidermis cells which were sectioned for the AFM to visualize the inner surface (closest to the plasma membrane) of the outer epidermal wall. The nm-wide cellulose microfibrils orientation and multilayer structure were clearly observed. The microfibril orientation and alignment tend to be more organized in older scales compared with younger scales. The onion epidermis cell wall was also used as a test analog to study cell wall elasticity by the AFM nanoindentation and the SAM V(z) feature. The novelty in this work was to demonstrate the capability of these two techniques to analyze isolated, single layered plant cell walls in their natural state. AFM nanoindentation was also used to probe the effects of Ethylenediaminetetraacetic acid (EDTA), and calcium ion treatment to modify pectin networks in cell walls. The results suggest a significant modulus increase in the calcium ion treatment and a slight decrease in EDTA treatment. To complement the AFM measurements, the HF-SAM was used to obtain the V(z) signatures of the onion epidermis. These measurements were focused on documenting the effect of pectinase enzyme treatment. The results indicate a significant change in the V(z) signature curves with time into the enzyme treatment. Thus AFM and HF-SAM open the door to a systematic nondestructive structure and mechanical property study of complex biological cell walls. A unique feature of this approach is that both microscopes allow the biological samples to be examined in their natural fluid (water) environment.

  15. Characterization of Core Samples from a Hardened Crust Layer in Tank 4F

    SciTech Connect

    Hay, M. L.

    2005-09-28

    Waste removal operations in Tank 4F are scheduled to begin in late 2005 to provide material for Sludge Batch 5. Mining/probing operations to support installation of submersible mixer pumps encountered a hard layer of material at {approx}45'' to 50'' from the bottom of the tank. Attempts at penetrating the hard layer using a manual mining tool in several different risers were not successful. A core-sampling tool was used to obtain samples of the hard crust layer in Tank 4F for characterization. Three 12'' core samples and a dip sample of the supernate near the surface of the hard layer were sent to Savannah River National Laboratory (SRNL) for characterization. X-ray Diffraction (XRD) results for the crystalline solids from both sample FTF-434 and FTF-435 identifies the major component of both samples as Burkeite (Na{sub 6}(CO{sub 3})(SO{sub 4}){sub 2}). All of the other data collected on the crystalline solids from the Tank 4F core samples support this conclusion. The conditions in Tank 4F for the last twenty years have been ideal for Burkeite formation. The tank has been largely undisturbed with a tank temperature consistently above 30 C, a carbonate to sulfate molar ratio in the supernate conducive to Burkeite formation, and slow evaporation of the supernate phase. Thermodynamic modeling and the results of a Burkeite solubility test confirm that a ratio of 1:1:12 for the volumes of Burkeite solids, supernate, and inhibited water will dissolve all of the Burkeite. These ratios could be used to remove the 6'' layer of Burkeite from Tank 4F with no mixing. However, the thermodynamic modeling and the solubility test neglect the sludge layer beneath the Burkeite crust in Tank 4F. Settled sludge in Savannah River Site (SRS) high-level waste tanks usually contains greater than 75% interstitial supernate by volume. If the supernate in the sludge layer should mix into the solution used to dissolve the Burkeite, significantly more inhibited water would be needed to dissolve the Burkeite layer. Additionally, the average thickness of the Burkeite layer across the diameter of the tank may be thicker or thinner than the 6'' assumed for modeling purposes. The 6'' thickness assumed for the Burkeite layer was based on the 6'' plug of solids found in one core sample. An average thickness greater than 6'' would increase the amount of water needed to dissolve the Burkeite.

  16. Optimization of real-time acoustical and mechanical monitoring of high intensity focused ultrasound (HIFU) treatment using harmonic motion imaging for high focused ultrasound (HMIFU).

    PubMed

    Hou, Gary Y; Marquet, Fabrice; Wang, Shutao; Konofagou, Elisa E

    2013-01-01

    Harmonic Motion Imaging (HMI) for Focused Ultrasound (HMIFU) is a recently developed high-intensity focused ultrasound (HIFU) treatment monitoring method with feasibilities demonstrated in silica, in vitro and in vivo. Its principle is based on emission of an Amplitude-modulated therapeutic ultrasound beam utilizing a therapeutic transducer to induce an oscillatory radiation force while tracking the focal tissue mechanical response during the HIFU treatment using a confocally-aligned diagnostic transducer. In order to translate towards the clinical implementation of HMIFU, a complete assessment study is required in order to investigate the optimal radiation force threshold for reliable monitoring the local tissue mechanical property changes, i.e., the estimation HMIFU displacement under thermal, acoustical, and mechanical effects within focal medium (i.e., boiling, cavitation, and nonlinearity) using biological specimen. In this study, HMIFU technique is applied on HIFU treatment monitoring on freshly excised ex vivo canine liver specimens. In order to perform the multi-characteristic assessment, the diagnostic transducer was operated as either a pulse-echo imager or Passive Cavitation Detector (PCD) to assess the acoustic and mechanical response, while a bare-wire thermocouple was used to monitor the focal temperature change. As the acoustic power of HIFU treatment was ranged from 2.3 to 11.4 W, robust HMI displacement was observed across the entire range. Moreover, an optimized range for high quality displacement monitoring was found to be between 3.6 to 5.2W, where displacement showed an increase followed by significant decrease, indicating a stiffening of focal medium due to thermal lesion formation, while the correlation coefficient was maintained above 0.95. PMID:24111176

  17. Threshold kinetic processes for t-C4F9I. [for solar-pumped lasers

    NASA Technical Reports Server (NTRS)

    Lee, J. H.; Wilson, J. W.; Humes, D. H.; Weaver, W. R.; Enderson, T.; Tabibi, B. M.

    1985-01-01

    To determine the relative threshold of the lasant gas t-C4F9I in comparison to n-C3F7I, the pump energy to reach threshold for photodissociation iodine lasing is measured in a common aparatus. The comparison is made for the threshold energies in the iodide pressure range up to 50 Torr when 64-J electric input into a flashlamp is used for pumping. It is shown from the results that qualitative differences between the thresholds of the two gases result from the degree to which steady state is achieved by the time threshold is reached. The estimated recombination rate for t-C4F9I is found to be much larger than the value given by Ershov et al (1978).

  18. Photochromism and Photomagnetism of a 3d-4f Hexacyanoferrate at Room Temperature.

    PubMed

    Cai, Li-Zhen; Chen, Qing-Song; Zhang, Cui-Juan; Li, Pei-Xin; Wang, Ming-Sheng; Guo, Guo-Cong

    2015-09-01

    Polycyanometallate compounds with both photochromism and photomagnetism have appealing applications in optical switches and memories, but such optical behaviors were essentially restricted to the cryogenic temperature. We realized, for the first time, the photochromism and photomagnetism of 3d-4f hexacyanoferrates at room temperature (RT) in [Eu(III)(18C6)(H2O)3]Fe(III)(CN)6·2H2O (18C6 = 18-crown-6). Photoinduced electron transfer (PET) from crown to Fe(III) yields long-lived charge-separated species at RT in air in the solid state and also weakens the magnetic susceptibility significantly. The PET mechanism and changing trend of photomagnetism differ significantly from those reported for known 3d-4f hexacyanoferrates. This work not only develops a new type of inorganic-organic hybrid photochromic material but opens a new avenue for RT photomagnetic polycyanometallate compounds. PMID:26284651

  19. Competition between 3d and 4f magnetism in Ce2Fe2S5

    NASA Astrophysics Data System (ADS)

    Schneidewind, A.; Mills, A. M.; Schnelle, W.; Stockert, O.; Ouladdiaf, B.; Ruck, M.

    2007-03-01

    Magnetic susceptibility measurements and neutron powder diffraction were performed on the rare-earth transition-metal sulfide Ce2Fe2S5 to study the effect of the substitution of nonmagnetic La(4f0) by Ce4f1). Ce2Fe2S5, which is isostructural to La2Fe2S5, contains Fe ions within chains of iron-sulfur octahedra and tetrahedra that are interconnected by Ce ions. Two antiferromagnetic phases, both with the propagation vector τ=({1}/{2} {1}/{2} 0), are observed: at 5 K⩽T⩽80 K ordering of the Fe moments is found; at T⩽5 K the Ce ions also participate in the magnetic ordering.

  20. Effectiveness of imaging seismic attenuation using visco-acoustic full waveform tomography: Examples from the Seattle Fault Zone and Northern Perth Basin

    NASA Astrophysics Data System (ADS)

    Takam Takougang, E.; Calvert, A. J.

    2012-12-01

    Attenuation characterizes the decrease in amplitude of seismic waves as they propagate away from the source. A seismic wave propagating in the subsurface will suffer from two types of attenuation: Intrinsic attenuation and scattering attenuation. Scattering attenuation is due to small scale heterogeneity in the subsurface, whereas intrinsic attenuation arises from inelastic rock properties. Intrinsic attenuation can provide key information about the subsurface, which can be of value to the mining as well as the oil and gas industry. However, accurate imaging of intrinsic seismic attenuation using visco-acoustic full-waveform tomography is not straight forward. Attenuation models recovered by visco-acoustic waveform tomography are often contain contaminated by scattering effects as well as elastic mode conversion artefacts due to the inability of the visco-acoustic approximation to perfectly predict the amplitude of visco-elastic field data. The effect of scattering can be reduced if a velocity model with a high resolution is used. This usually necessitates a two-step inversion approach consisting of first recovering the velocity model and later, the attenuation model. In this study, we present a specific preconditioning of the data based on matching the amplitude variation with offset (AVO) of the field and modelled visco-acoustic data, and a specific inversion approach based on a sequential recovering of the seismic velocity and attenuation models using the visco-acoustic approximation. Our purpose is to improve the quality of the recovered attenuation model by decoupling the reconstruction of velocity and attenuation, thus reducing artefacts. We apply the method to two different areas: The Seattle Fault Zone in Puget Sound in the northwestern USA, using marine seismic reflection data from the Seismic Hazards investigation in Puget Sound (SHIPS) survey collected in 1998, and the Allanooka area within the Northern Perth Basin using high resolution seismic reflection data collected in 2010 for groundwater modelling. In the Allanooka area, we investigate the use of joint inversion of controlled source electromagnetic (CSEM) and seismic data to obtain a more accurate starting velocity model for full-waveform tomography, where the starting usable frequency for waveform tomography is relatively large. We assess the reliability of the results with a set of visco-elastic modelling tests.

  1. Tunable interplay between 3d and 4f electrons in Co-doped iron pnictides

    NASA Astrophysics Data System (ADS)

    Shang, T.; Yang, L.; Chen, Y.; Cornell, N.; Ronning, F.; Zhang, J. L.; Jiao, L.; Chen, Y. H.; Chen, J.; Howard, A.; Dai, J.; Thompson, J. D.; Zakhidov, A.; Salamon, M. B.; Yuan, H. Q.

    2013-02-01

    We study the interplay of 3d and 4f electrons in the iron pnictides CeFe1-xCoxAsO and GdFe1-yCoyAsO, which correspond to two very different cases of 4f-magnetic moment. Both CeFeAsO and GdFeAsO undergo a spin-density-wave (SDW) transition associated with Fe 3d electrons at high temperatures, which is rapidly suppressed by Fe/Co substitution. Superconductivity appears in a narrow doping range: 0.054f electrons form an antiferromagnetic (AFM) order at low temperatures over the entire doping range and Co 3d electrons are ferromagnetically ordered on the Co-rich side; the Curie temperature reaches TCCo? 75 K at x=1 and y=1. In the Ce compounds, the Nel temperature TNCe increases upon suppressing the SDW transition of Fe and then remains nearly unchanged with further increasing Co concentration up to x?0.8 (TNCe? 4 K). Furthermore, evidence of Co-induced polarization on Ce moments is observed on the Co-rich side. In the Gd compounds, the two magnetic species of Gd and Co are coupled antiferromagnetically to give rise to ferrimagnetic behavior in the magnetic susceptibility on the Co-rich side. For 0.7?y<1.0, the system undergoes a possible magnetic reorientation below the Nel temperature of Gd (TNGd). Our results suggest that the effects of both electron hybridizations and magnetic exchange coupling between the 3d-4f electrons give rise to a rich phase diagram in the rare-earth iron pnictides.

  2. Long-term tropospheric trend of octafluorocyclobutane (c-C4F8 or PFC-318)

    NASA Astrophysics Data System (ADS)

    Oram, D. E.; Mani, F. S.; Laube, J. C.; Newland, M. J.; Reeves, C. E.; Sturges, W. T.; Penkett, S. A.; Brenninkmeijer, C. A. M.; Rckmann, T.; Fraser, P. J.

    2012-01-01

    Air samples collected at Cape Grim, Tasmania between 1978 and 2008 and during a series of more recent aircraft sampling programmes have been analysed to determine the atmospheric abundance and trend of octafluorocyclobutane (c-C4F8 or PFC-318). c-C4F8 has an atmospheric lifetime in excess of 3000 yr and a global warming potential (GWP) of 10 300 (100 yr time horizon), making it one of the most potent greenhouse gases detected in the atmosphere to date. The abundance of c-C4F8 in the Southern Hemisphere has risen from 0.35 ppt in 1978 to 1.2 ppt in 2010, and is currently increasing at a rate of around 0.03 ppt yr-1. It is the third most abundant perfluorocarbon (PFC) in the present day atmosphere, behind CF4 (~75 ppt) and C2F6 (~4 ppt). Although a number of potential sources of c-C4F8 have been reported, including the electronics and semi-conductor industries, there remains a large discrepancy in the atmospheric budget. Using a 2-D global model to derive top-down global emissions based on the Cape Grim measurements yields a recent (2007) emission rate of around 1.1 Gg yr-1 and a cumulative emission up to and including 2007 of 38.1 Gg. Emissions reported on the EDGAR emissions database for the period 1986-2005 represent less than 1% of the top-down emissions for the same period, which suggests there is a large unaccounted for source of this compound. It is also apparent that the magnitude of this source has varied considerably over the past 30 yr, declining sharply in the late 1980s before increasing again in the mid-1990s.

  3. Long-term tropospheric trend of octafluorocyclobutane (c-C4F8 or PFC-318)

    NASA Astrophysics Data System (ADS)

    Oram, D. E.; Mani, F. S.; Laube, J. C.; Newland, M. J.; Reeves, C. E.; Sturges, W. T.; Penkett, S. A.; Brenninkmeijer, C. A. M.; Rckmann, T.; Fraser, P. J.

    2011-07-01

    Air samples collected at Cape Grim, Tasmania between 1978 and 2008 and during a series of more recent aircraft sampling programmes have been analysed to determine the atmospheric abundance and trend of octafluorocyclobutane (-C4F8 or PFC-318). c-C4F8 has an atmospheric lifetime in excess of 3000 yr and a global warming potential (GWP) of 10 300 (100 yr time horizon), making it one of the most potent greenhouse gases detected in the atmosphere to date. The abundance of c-C4F8 in the Southern Hemisphere has risen from 0.35 ppt in 1978 to 1.2 ppt in 2010, and is currently increasing at a rate of around 0.03 ppt yr-1. It is the third most abundant perfluorocarbon (PFC) in the present day atmosphere, behind CF4 (~75 ppt) and C2F6 (~4 ppt). The origin of c-C4F8 is unclear. Using a 2-D global model to derive top-down global emissions based on the Cape Grim measurements yields a recent (2007) emission rate of around 1.1 Gg yr-1 and a cumulative emission up to and including 2007 of 38.1 Gg. Emissions reported on the EDGAR emissions database for the period 1986-2005 represent less than 1 % of the top-down emissions for the same period, which suggests there is a large unaccounted for source of this compound. It is also apparent that the magnitude of this source has varied considerably over the past 30 yr, declining sharply in the late 1980s before increasing again in the mid-1990s.

  4. Requirement of the eukaryotic translation initiation factor 4F complex in hepatitis E virus replication.

    PubMed

    Zhou, Xinying; Xu, Lei; Wang, Yijin; Wang, Wenshi; Sprengers, Dave; Metselaar, Herold J; Peppelenbosch, Maikel P; Pan, Qiuwei

    2015-12-01

    Hepatitis E virus (HEV) infection, one of the foremost causes of acute hepatitis, is becoming a health problem of increasing magnitude. As other viruses, HEV exploits elements from host cell biochemistry, but we understand little as to which components of the human hepatocellular machinery are perverted for HEV multiplication. It is, however, known that the eukaryotic translation initiation factors 4F (eIF4F) complex, the key regulator of the mRNA-ribosome recruitment phase of translation initiation, serves as an important component for the translation and replication of many viruses. Here we aim to investigate the role of three subunits of the eIF4F complex: eukaryotic translation initiation factor 4A (eIF4A), eukaryotic translation initiation factor 4G (eIF4G) and eukaryotic translation initiation factor 4E (eIF4E) in HEV replication. We found that efficient replication of HEV requires eIF4A, eIF4G and eIF4E. Consistently, the negative regulatory factors of this complex: programmed cell death 4 (PDCD4) and eIF4E-binding protein 1 (4E-BP1) exert anti-HEV activities, which further illustrates the requirement for eIF4A and eIF4E in supporting HEV replication. Notably, phosphorylation of eIF4E induced by MNK1/2 activation is not involved in HEV replication. Although ribavirin and interferon-? (IFN-?), the most often-used off-label drugs for treating hepatitis E, interact with this complex, their antiviral activities are independent of eIF4E. In contrast, eIF4E silencing provokes enhanced anti-HEV activity of these compounds. Thus, HEV replication requires eIF4F complex and targeting essential elements of this complex provides important clues for the development of novel antiviral therapy against HEV. PMID:26526587

  5. Extended analysis of the 5g. -->. 4f emissions in H/sub 2/

    SciTech Connect

    Chang, E.S.; Pulchtopek, S.; Eyler, E.E.

    1984-01-15

    An analysis starting from Hund's case d has been used to extend the work of Herzberg and Jungen on the 5g..-->..4f emissions in H/sub 2/. A simple analytical expression for the line intensities is presented that agrees with their calculations is about 1%. All of the experimentally observed lines have been accounted for by including higher vibrational levels in our calculations.

  6. Contribution of Eu 4f states to the magnetic anisotropy of EuO

    SciTech Connect

    Arenholz, E.; Schmehl, A.; Schlom, D.G.; van der Laan, G.

    2008-09-11

    Anisotropic x-ray magnetic linear dichroism (AXMLD) provides a novel element-, site-, shell-, and symmetry-selective techniques to study the magnetic anisotropy induced by a crystalline electric field. The weak Eu2+ M4,5 AXMLD observed in EuO(001) indicates that the Eu 4f states are not rotationally invariant and hence contribute weakly to the magnetic anisotropy of EuO. The results are contrasted with those obtained for 3d transition metal oxides.

  7. Superhydrophobic treatment using atmospheric-pressure He/C4F8 plasma for buoyancy improvement

    NASA Astrophysics Data System (ADS)

    Noh, Sooryun; Moon, A.-Young; Moon, Se Youn

    2015-04-01

    A superhydrophobic miniature boat was fabricated with aluminum alloy plates treated with atmospheric-pressure helium (He)/octafluorocyclobutane (C4F8) plasma using 13.56 MHz rf power. When only 0.13% C4F8 was added to He gas, the contact angle of the surface increased to 140 and the surface showed superhydrophobic properties. On the basis of chemical and morphological analyses, fluorinated functional groups (CF, CF2, and CF3) and nano-/micro-sized particles were detected on the Al surface. These features brought about superhydrophobicity similar to the lotus effect. While the miniature boat, assembled with plasma-treated plates, was immersed in water, a layer of air (i.e., a plastron) surrounded the superhydrophobic surfaces. This effect contributed to the development of a 4.7% increase in buoyancy. In addition, the superhydrophobic properties lasted for two months under the submerged condition. These results demonstrate that treatment with atmospheric-pressure He/C4F8 plasma is a promising method of improving the load capacity and antifouling properties, and reducing the friction of marine ships through a fast and low-cost superhydrophobic treatment process.

  8. Ligand field effects on the multiplet structure of the U4f XPS of UO2

    SciTech Connect

    Ilton, Eugene S.; Bagus, Paul S.

    2008-03-01

    Ab initio, fully relativistic four component theory was used to determine atomic and interatomic many-body effects for the 4f X-ray photoelectron spectrum of an embedded UO8-12 cluster representing UO2. Many-body effects were included through the use of configuration interaction wavefunctions that allow the mixing of XPS allowed and XPS forbidden configurations. Charge transfer configurations were not included. This work extends our earlier studies on simulations of the U 4f XPS for the free U4+ cation. While the main XPS features are similar in both cases, ligand field effects changed the multiplet structure in important ways that better simulated experimental data for UO2. Neither initial nor final state covalency significantly reduced the 4f-5f exchange integrals, and the differences between the atom and cluster model was due to ligand field splitting of the 5f band and increased distributions of intensity from XPS allowed to XPS forbidden peaks. The prominent 7 eV satellites associated with UO2 were absent in the simulations, and provides further evidence that these satellites are due to charge transfer and not other interatomic effects.

  9. Utilizing 3d-4f magnetic interaction to slow the magnetic relaxation of heterometallic complexes.

    PubMed

    Li, Xiao-Lei; Min, Fan-Yong; Wang, Chao; Lin, Shuang-Yan; Liu, Zhiliang; Tang, Jinkui

    2015-05-01

    The synthesis, structural characterization, and magnetic properties of four related heterometallic complexes with formulas [Dy(III)2Co(II)(C7H5O2)8]6H2O (1), [Dy(III)2Ni(II)(C7H5O2)8](C7H6O2)2 (2), Tb(III)2Co(II)(C7H5O2)8 (3), and Dy(III)2Cd(II)(C7H5O2)8 (4) were reported. Each of complexes has a perfectly linear arrangement of the metal ions with two terminal Ln(III) (Ln(III) = Dy(III), Tb(III)) ions and one central M(II) (M(II) = Co(II), Ni(II), Cd(II)) ion. It was found that 1-3 displayed obvious magnetic interactions between the spin carriers according to the direct current (dc) susceptibility measurements. Alternating current (ac) magnetic susceptibility measurements indicate that complexes 1-4 all exhibit single-molecule magnet (SMM) behavior, while the replacement of the diamagnetic Cd(II) by paramagnetic ions leads to a significant slowing of the relaxation thanks to the magnetic interactions between 3d and 4f ions, resulting in higher relaxation barrier for complexes 1 and 2. Moreover, both Dy2Co and Dy2Ni compounds exhibit dual relaxation pathways that may originate from the single ion behavior of individual Dy(III) ions and the coupling between Dy(III) and Co(II)/Ni(II) ions, respectively, which can be taken as the feature of 3d-4f SMMs. The Ueff for 1 of 127 K is a relatively high value among the reported 3d-4f SMMs. The results demonstrate that the magnetic coupling between 3d and 4f ions is crucial to optimize SMM parameters. The synthetic approach illustrated in this work represents an efficient route to design nd-4f based SMMs via incorporating suitable paramagnetic 3d and even 4d and 5d ions into the d-f system. PMID:25906391

  10. A rail system for circular synthetic aperture sonar imaging and acoustic target strength measurements: Design/operation/preliminary results

    NASA Astrophysics Data System (ADS)

    Kennedy, J. L.; Marston, T. M.; Lee, K.; Lopes, J. L.; Lim, R.

    2014-01-01

    A 22 m diameter circular rail, outfitted with a mobile sonar tower trolley, was designed, fabricated, instrumented with underwater acoustic transducers, and assembled on a 1.5 m thick sand layer at the bottom of a large freshwater pool to carry out sonar design and target scattering response studies. The mobile sonar tower translates along the rail via a drive motor controlled by customized LabVIEW software. The rail system is modular and assembly consists of separately deploying eight circular arc sections, measuring a nominal center radius of 11 m and 8.64 m arc length each, and having divers connect them together in the underwater environment. The system enables full scale measurements on targets of interest with 0.1 angular resolution over a complete 360 aperture, without disrupting target setup, and affording a level of control over target environment conditions and noise sources unachievable in standard field measurements. In recent use, the mobile cart carrying an instrumented sonar tower was translated along the rail in 720 equal position increments and acoustic backscatter data were acquired at each position. In addition, this system can accommodate both broadband monostatic and bistatic scattering measurements on targets of interest, allowing capture of target signature phenomena under diverse configurations to address current scientific and technical issues encountered in mine countermeasure and unexploded ordnance applications. In the work discussed here, the circular rail apparatus is used for acoustic backscatter testing, but this system also has the capacity to facilitate the acquisition of magnetic and optical sensor data from targets of interest. A brief description of the system design and operation will be presented along with preliminary processed results for data acquired from acoustic measurements conducted at the Naval Surface Warfare Center, Panama City Division Test Pond Facility. [Work Supported by the U.S. Office of Naval Research and The Strategic Environmental Research and Development Program.

  11. Acoustic hemostasis

    NASA Astrophysics Data System (ADS)

    Crum, Lawrence; Beach, Kirk; Carter, Stephen; Chandler, Wayne; Curra, Francesco; Kaczkowski, Peter; Keilman, George; Khokhlova, Vera; Martin, Roy; Mourad, Pierre; Vaezy, Shahram

    2000-07-01

    In cases of severe injury, physicians speak of a "golden hour"—a brief grace period in which quickly applied, proper therapy can save the life of the patient. Much of this mortality results from exsanguination, i.e., bleeding to death—often from internal hemorrhage. The inability of a paramedic to treat breaches in the vascular system deep within the body or to stem the loss of blood from internal organs is a major reason for the high level of mortality associated with blunt trauma. We have undertaken an extensive research program to treat the problem of internal bleeding. Our approach is as follows: (a) We use scanning ultrasound to identify internal bleeding and hemorrhage, (b) we use ultrasound imaging to locate specific breaches in the vascular system, both from damaged vessels and gross damage to the capillary bed, and (c) we use High Intensity Focused Ultrasound (HIFU) to treat the damaged region and to induce hemostasis. We present a general review of this research with some emphasis on the role of nonlinear acoustics.

  12. Musical Acoustics

    NASA Astrophysics Data System (ADS)

    Gough, Colin

    This chapter provides an introduction to the physical and psycho-acoustic principles underlying the production and perception of the sounds of musical instruments. The first section introduces generic aspects of musical acoustics and the perception of musical sounds, followed by separate sections on string, wind and percussion instruments.

  13. Molecular modeling and identification of substrate binding site of orphan human cytochrome P450 4F22.

    PubMed

    Kumar, Suresh

    2011-01-01

    Cytochrome P450s are superfamily of heme proteins which generally monooxygenate hydrophobic compounds. The human cytochrome P450 4F22 (CYP4F22) was categorized into "orphan" CYPs because of its unknown function. CYP4F22 is a potential drug target for cancer therapy. However, three-dimensional structure, the active site topology and substrate specificity of CYP4F22 remain unclear. In this study, a three-dimensional model of human P450 4F22 was constructed by comparative modeling using Modeller 9v5. The resulting model was refined by energy minimization subjected to the quality assessment from both geometric and energetic aspects and was found to be of reasonable quality. Docking approach was employed to dock arachidonic acid into the active site of CYP4F22 in order to probe the ligand-binding modes. As a result, several key residues were identified to be responsible for the binding of arachidonic acid with CYP4F22. These findings provide useful information for understanding the biological roles of CYP4F22 and structure-based drug design. PMID:22102778

  14. Radiation-force-based estimation of acoustic attenuation using harmonic motion imaging (HMI) in phantoms and in vitro livers before and after HIFU ablation

    NASA Astrophysics Data System (ADS)

    Chen, Jiangang; Hou, Gary Y.; Marquet, Fabrice; Han, Yang; Camarena, Francisco; Konofagou, Elisa

    2015-10-01

    Acoustic attenuation represents the energy loss of the propagating wave through biological tissues and plays a significant role in both therapeutic and diagnostic ultrasound applications. Estimation of acoustic attenuation remains challenging but critical for tissue characterization. In this study, an attenuation estimation approach was developed using the radiation-force-based method of harmonic motion imaging (HMI). 2D tissue displacement maps were acquired by moving the transducer in a raster-scan format. A linear regression model was applied on the logarithm of the HMI displacements at different depths in order to estimate the acoustic attenuation. Commercially available phantoms with known attenuations (n=5 ) and in vitro canine livers (n=3 ) were tested, as well as HIFU lesions in in vitro canine livers (n=5 ). Results demonstrated that attenuations obtained from the phantoms showed a good correlation ({{R}2}=0.976 ) with the independently obtained values reported by the manufacturer with an estimation error (compared to the values independently measured) varying within the range of 15-35%. The estimated attenuation in the in vitro canine livers was equal to 0.32??????0.03 dB cm-1 MHz-1, which is in good agreement with the existing literature. The attenuation in HIFU lesions was found to be higher (0.58??????0.06 dB cm-1 MHz-1) than that in normal tissues, also in agreement with the results from previous publications. Future potential applications of the proposed method include estimation of attenuation in pathological tissues before and after thermal ablation.

  15. Red nucleus and rubrospinal tract disorganization in the absence of Pou4f1

    PubMed Central

    Martinez-Lopez, Jesus E.; Moreno-Bravo, Juan A.; Madrigal, M. Pilar; Martinez, Salvador; Puelles, Eduardo

    2015-01-01

    The red nucleus (RN) is a neuronal population that plays an important role in forelimb motor control and locomotion. Histologically it is subdivided into two subpopulations, the parvocellular RN (pRN) located in the diencephalon and the magnocellular RN (mRN) in the mesencephalon. The RN integrates signals from motor cortex and cerebellum and projects to spinal cord interneurons and motor neurons through the rubrospinal tract (RST). Pou4f1 is a transcription factor highly expressed in this nucleus that has been related to its specification. Here we profoundly analyzed consequences of Pou4f1 loss-of-function in development, maturation and axonal projection of the RN. Surprisingly, RN neurons are specified and maintained in the mutant, no cell death was detected. Nevertheless, the nucleus appeared disorganized with a strong delay in radial migration and with a wider neuronal distribution; the neurons did not form a compacted population as they do in controls, Robo1 and Slit2 were miss-expressed. Cplx1 and Npas1, expressed in the RN, are transcription factors involved in neurotransmitter release, neuronal maturation and motor function processes among others. In our mutant mice, both transcription factors are lost, suggesting an abnormal maturation of the RN. The resulting altered nucleus occupied a wider territory. Finally, we examined RST development and found that the RN neurons were able to project to the spinal cord but their axons appeared defasciculated. These data suggest that Pou4f1 is necessary for the maturation of RN neurons but not for their specification and maintenance. PMID:25698939

  16. Transitions between the 4 f -core-excited states in Ir16 +,Ir17 +, and Ir18 + ions for clock applications

    NASA Astrophysics Data System (ADS)

    Safronova, U. I.; Flambaum, V. V.; Safronova, M. S.

    2015-08-01

    Iridium ions near 4 f -5 s level crossings are the leading candidates for a new type of atomic clocks with a high projected accuracy and a very high sensitivity to the temporal variation of the fine structure constant ? . To identify spectra of these ions in experiment accurate calculations of the spectra and electromagnetic transition probabilities should be performed. Properties of the 4 f -core-excited states in Ir16 +,Ir17 +, and Ir18 + ions are evaluated using relativistic many-body perturbation theory and Hartree-Fock-relativistic method (COWAN code). We evaluate excitation energies, wavelengths, oscillator strengths, and transition rates. Our large-scale calculations included the following set of configurations: 4 f145 s ,4 f145 p ,4 f135 s2,4 f135 p2,4 f135 s 5 p ,4 f125 s25 p , and 4 f125 s 5 p2 in Pm-like Ir16 +; 4 f14,4 f135 s ,4 f135 p ,4 f125 s2,4 f125 s 5 p , and 4 f125 p2 in Nd-like Ir17 +; and 4 f13,4 f125 s ,4 f125 p ,4 f115 s2 , and 4 f115 s 5 p in Pr-like Ir18 +. The 5 s -5 p transitions are illustrated by the synthetic spectra in the 180-200 range. Large contributions of magnetic-dipole transitions to lifetimes of low-lying states in the region below 2.5 Ry are demonstrated.

  17. 4-[F-18]fluoroproline: A potential tracer for collagen synthesis. Radiosynthesis and biological evaluation

    SciTech Connect

    Hamacher, K.; Herz, M.; Truckenbrodt, R.

    1996-05-01

    Proline is an important constituent of the structural protein collagen. It has been shown that its fluorinated analogs (2S,4S)- and particularly (2S,4R)-4-fluoroproline are also incorporated into collagen (Gottlieb et al., Biochemistry (1965), 4: 2507). 4-[F-18]fluoroproline is therefore a potential probe for studying abnormal collagen synthesis e. g. in tumors, lung fibrosis and liver cirrhosis. We have evaluated the two diastereomeric forms using a transplantable osteosarcoma in mice as an in vivo model for elevated collagen synthesis, and a MCF 7 mamma carcinoma cell line for monolayer incubation studies.

  18. Molecular modelling insights into DFNA15 mediated enhancement of POU4F3 stability.

    PubMed

    Frenz, Christopher M; Lefebvre, Philippe P

    2008-01-01

    The POU4F3 transcription factor is expressed in the cochlear and vestibular hair cells of the inner ear and its targeted deletion results in a loss of inner ear hair cells. The DFNA15 truncation mutation has been demonstrated to result in a loss of transcriptional activity, but an increase in the stability of the protein. Molecular modelling is utilised to propose a mechanism of stability enhancement, via an interaction between the truncated POU(HD) domain and the POU(S) domain of the transcription factor. PMID:20054994

  19. Multiple Scattering Effects on Spin Polarized XPD Spectra from W 4f Levels

    NASA Astrophysics Data System (ADS)

    Nakayama, Kentaro; Konishi, Takehisa; Fujikawa, Takashi; Rennert, Peter

    1999-10-01

    Spin polarization in core-level photoemission usinglinearly polarized light can occur through the spin-orbitinteraction. Although this has purely atomic origin,in sold state there would be considerable effect of scattering ofthe photoelectrons from neighboring atoms, which is referred asphotoelectron diffraction. We have theoretically investigatedthe effect of multiple scattering on angular and energy dependenceof the spin polarization of W 4f core-level photoemission spectrafrom W(110) surface,and found a large difference from the case of an isolated atom.Scattering from surrounding atoms have improved the agreementwith experiment.

  20. XeCl laser pumped iodine laser using t-C4F9I

    NASA Technical Reports Server (NTRS)

    Hwang, In Heon; Han, Kwang S.; Lee, Ja H.

    1989-01-01

    An iodine photodissociation laser using t-C4F9I as the active material was pumped by a XeCl laser. An iodine laser output energy of 3 mJ with pulse duration of 25 ns was obtained when the pumping pulse energy was 80 mJ, the iodine pressure was 70 torr, and the reflectance of the output mirror was 85 percent. The high pumping efficiency and low threshold pump power achieved in this experiment are attributable to the high absorption cross section at the pump laser wavelength (308 nm) of the iodide used.

  1. XeCl laser pumped iodine laser using t-C4F9I

    NASA Technical Reports Server (NTRS)

    Hwang, In Heon; Han, Kwang S.

    1989-01-01

    An iodine photodissociation laser using t-C4F9I as the active material was pumped by an XeCl laser. An iodine laser output energy of 3 mJ with pulse duration of 25 ns was obtained when the pumping pulse energy was 80 mJ, the iodide pressure was 70 torr, and the reflectance of the output mirror was 85 percent. The high pumping efficiency and low threshold pump power achieved in this experiment are attributable to the high absorption cross section at the pump laser wavelength (308 nm) of the iodide used.

  2. Evidence for the photoemission nature of Gd 4f resonant photoemission

    SciTech Connect

    Mishra, S.R.; Gammon, W.J.; Cummins, T.R.; Waddill, G.D.; Laan, G. van der; Goodman, K.W.; Tobin, J.G.

    1998-12-31

    The constructive interference between direct and indirect channels above the absorption threshold of a core level leads to a massive increase in the emission cross section leading to a phenomenon called resonant photoemission. Using novel magnetic linear dichroism in angular distribution photoelectron spectroscopy experiment, the authors have tried to understand the nature of the resonant photoemission process in Gd metal. The presence of dichroism in Gd 4f photoemission intensity at a photo energy corresponding to resonant photoemission clearly demonstrates the photoemission-like nature of the resonant photoemission process.

  3. Acoustic-emission linear-pulse holography

    SciTech Connect

    Collins, H.D.; Lemon, D.K.; Busse, L.J.

    1982-06-01

    This paper describes Acoustic Emission Linear Pulse Holography which combines the advantages of linear imaging and acoustic emission into a single NDE inspection system. This unique system produces a chronological linear holographic image of a flaw by utilizing the acoustic energy emitted during crack growth. Conventional linear holographic imaging uses an ultrasonic transducer to transmit energy into the volume being imaged. When the crack or defect reflects that energy, the crack acts as a new source of acoustic waves. To formulate an image of that source, a receiving transducer is scanned over the volume of interest and the phase of the received signals is measured at successive points on the scan. The innovation proposed here is the utilization of the crack generated acoustic emission as the acoustic source and generation of a line image of the crack as it grows. A thirty-two point sampling array is used to construct phase-only linear holograms of simulated acoustic emission sources on large metal plates. The phases are calculated using the pulse time-of-flight (TOF) times from the reference transducer to the array of receivers. Computer reconstruction of the image is accomplished using a one-dimensional FFT algorithm (i.e., backward wave). Experimental results are shown which graphically illustrate the unique acoustic emission images of a single point and a linear crack in a 100 mm x 1220 mm x 1220 mm aluminum plate.

  4. Revealing, identifying, and assessing flaws in operating equipment by the acoustic emission image recognition method under strong background noise condition

    NASA Astrophysics Data System (ADS)

    Muravin, Gregory; Muravin, Boris; Lezvisky, Ludmila

    2004-05-01

    The analysis has shown that high pressure and high temperature piping in fossil and nuclear power plants suffer from unexpected and rarely predictable failures. To guarantee operational safety and to prevent failures authors have performed the complex investigations and have created Quantitative Acoustic Emission NDI technology for revealing, identifying and assessing flaws in equipment operated under strong background noise condition. These enabled: Overall inspection of the piping operated under stress, temperature, pressure, steam flow and loading, variation. Locating suspected zones and zones of flaw development with low J-integral value and the great variation of the dynamic range of flaws danger level. Identification of flaw types and their danger level. Detection of defective components in service prior to shut down. The continuous and the burst Acoustic Emission (AE) were used in combination as an information tool. As result, the significant number of flaws such as creep at stage 3a-3b, closed-edge micro-cracks, systems of randomly dispersed pores and inclusions, plastic deformation development around them, or/and individual micro-cracking were revealed, identified and assessed in 50 operating high energy piping. The findings and assessing flaw danger level obtained by QAE NDI were confirmed by independent NDI methods as TOFD, X-ray, replication, metallurgical investigations, etc. The findings and assessing flaw danger level obtained by QAE NDI were confirmed by independent NDI methods such as TOFD, X-ray, replication, metallurgical investigations, etc

  5. 4F Peptide reduces nascent atherosclerosis and induces natural antibody production in apolipoprotein E-null mice

    PubMed Central

    Wool, Geoffrey D.; Cabana, Veneracion G.; Lukens, John; Shaw, Peter X.; Binder, Christoph J.; Witztum, Joseph L.; Reardon, Catherine A.; Getz, Godfrey S.

    2011-01-01

    Our objective was to contrast the effect of apolipoprotein (apo) A-I mimetic peptides, such as 4F and 4F-Pro-4F (Pro), on nascent and mature atherosclerotic lesions and on levels of antibodies against oxidation-specific epitopes. Chow-fed apoE?/? mice were injected intraperitoneally with either the 4F peptide or a tandem helix apoA-I mimetic peptide (Pro) every other day. Mice treated with 4F, but not Pro, for 4 wk starting at 10 wk of age showed a dramatic decrease in atherosclerosis at 2 arterial sites. However, neither peptide was effective in mice treated for 8 wk starting at 20 wk of age; lesions were larger and more mature at this time point. Peptide treatment caused increased production of antibodies against oxidation-specific epitopes, including a disproportionate induction of the IgM natural antibody (NAb) E06/T15 to oxidized phospholipids. In summary, 4F, but not the tandem peptide Pro, effectively inhibited early atherogenesis but was ineffective against more mature lesions. Two different apoA-I mimetic peptides increased titers of natural antibodies against oxidation-specific epitopes.Wool, G. D., Cabana, V. G., Lukens, J., Shaw, P. X., Binder, C. J., Witztum, J. L., Reardon, C. A., Getz, G. S. 4F Peptide reduces nascent atherosclerosis and induces natural antibody production in apolipoprotein E-null mice. PMID:20876212

  6. 4-D imaging of seepage in earthen embankments with time-lapse inversion of self-potential data constrained by acoustic emissions localization

    NASA Astrophysics Data System (ADS)

    Rittgers, J. B.; Revil, A.; Planes, T.; Mooney, M. A.; Koelewijn, A. R.

    2015-02-01

    New methods are required to combine the information contained in the passive electrical and seismic signals to detect, localize and monitor hydromechanical disturbances in porous media. We propose a field experiment showing how passive seismic and electrical data can be combined together to detect a preferential flow path associated with internal erosion in a Earth dam. Continuous passive seismic and electrical (self-potential) monitoring data were recorded during a 7-d full-scale levee (earthen embankment) failure test, conducted in Booneschans, Netherlands in 2012. Spatially coherent acoustic emissions events and the development of a self-potential anomaly, associated with induced concentrated seepage and internal erosion phenomena, were identified and imaged near the downstream toe of the embankment, in an area that subsequently developed a series of concentrated water flows and sand boils, and where liquefaction of the embankment toe eventually developed. We present a new 4-D grid-search algorithm for acoustic emissions localization in both time and space, and the application of the localization results to add spatially varying constraints to time-lapse 3-D modelling of self-potential data in the terms of source current localization. Seismic signal localization results are utilized to build a set of time-invariant yet spatially varying model weights used for the inversion of the self-potential data. Results from the combination of these two passive techniques show results that are more consistent in terms of focused ground water flow with respect to visual observation on the embankment. This approach to geophysical monitoring of earthen embankments provides an improved approach for early detection and imaging of the development of embankment defects associated with concentrated seepage and internal erosion phenomena. The same approach can be used to detect various types of hydromechanical disturbances at larger scales.

  7. Acoustic Holography

    NASA Astrophysics Data System (ADS)

    Kim, Yang-Hann

    One of the subtle problems that make noise control difficult for engineers is the invisibility of noise or sound. A visual image of noise often helps to determine an appropriate means for noise control. There have been many attempts to fulfill this rather challenging objective. Theoretical (or numerical) means for visualizing the sound field have been attempted, and as a result, a great deal of progress has been made. However, most of these numerical methods are not quite ready for practical applications to noise control problems. In the meantime, rapid progress with instrumentation has made it possible to use multiple microphones and fast signal-processing systems. Although these systems are not perfect, they are useful. A state-of-the-art system has recently become available, but it still has many problematic issues; for example, how can one implement the visualized noise field. The constructed noise or sound picture always consists of bias and random errors, and consequently, it is often difficult to determine the origin of the noise and the spatial distribution of the noise field. Section 26.2 of this chapter introduces a brief history, which is associated with sound visualization, acoustic source identification methods and what has been accomplished with a line or surface array. Section 26.2.3 introduces difficulties and recent studies, including de-Dopplerization and de-re verberation methods, both essential for visualizing a moving noise source, such as occurs for cars or trains. This section also addresses what produces ambiguity in realizing real sound sources in a room or closed space. Another major issue associated with sound/noise visualization is whether or not we can distinguish between mutual dependencies of noise in space (Sect. 26.2.4); for example, we are asked to answer the question, Can we see two birds singing or one bird with two beaks?

  8. Sequential Synthesis of 3d-3d'-4f Heterometallic Heptanuclear Clusters in between Lacunary Polyoxometalates.

    PubMed

    Sato, Rinta; Suzuki, Kosuke; Minato, Takuo; Yamaguchi, Kazuya; Mizuno, Noritaka

    2016-03-01

    In this work, we have successfully created several unprecedented discrete 3d-3d'-4f heterotrimetallic clusters in between lacunary polyoxometalates (POMs). By the three-step sequential introduction of metal cations into a trivacant lacunary POM TBA4H6[A-α-SiW9O34] (TBA = tetra-n-butylammonium) in organic media, five kinds of sandwich-type POMs with double-diamond-shaped 3d-3d'-4f heptanuclear clusters (IIIFeM4Ln2, TBAnHm[FeM4{Ln(L)2}2O2(A-α-SiW9O34)2], M = Mn(3+), Cu(2+); Ln = Gd(3+), Dy(3+), Lu(3+); L = acac (acetylacetonate), hfac (hexafluoroacetylacetonate)) were successfully synthesized for the first time. By introduction of two [Ln(L)2](+) units on the ends of pentanuclear clusters [FeMn4O18(OH)2](23-) and [FeCu4O18(OH)2](27-), the magnetic interactions between Mn(3+)-Mn(3+) and Cu(2+)-Cu(2+) could be modulated. Among a series of the heterometallic heptanuclear compounds, IIIFeMn4Lu2 exhibited the slow magnetic relaxation characteristic for a single-molecule magnet under the zero applied magnetic fields. PMID:26914662

  9. Lattice dynamics and elastic properties of the 4f electron system: CeN

    NASA Astrophysics Data System (ADS)

    Kanchana, V.; Vaitheeswaran, G.; Zhang, Xinxin; Ma, Yanming; Svane, A.; Eriksson, O.

    2011-11-01

    The electronic structure, structural stability, and lattice dynamics of cerium mononitride are investigated using ab initio density-functional methods involving an effective potential derived from the generalized gradient approximation and without special treatment for the 4f states. The 4f states are hence allowed to hop from site to site, without an on-site Hubbard U, and contribute to the bonding, in a picture often referred to as itinerant. It is argued that this picture is appropriate for CeN at low temperatures, while the anomalous thermal expansion observed at elevated temperatures indicates entropy-driven localization of the Ce f electrons, similar to the behavior of elemental cerium. The elastic constants are predicted from the total energy variation of strained crystals and are found to be large, typical for nitrides. The phonon dispersions are calculated showing no soft modes, and the Grneisen parameter behaves smoothly. The electronic structure is also calculated using the quasiparticle self-consistent GW approximation (where G denotes the Green's function and W denotes the screened interaction). The Fermi surface of CeN is dominated by large egg-shaped electron sheets centered on the X points, which stem from the p-f mixing around the X point. In contrast, assuming localized f electrons leads to a semimetallic picture with small band overlaps around X.

  10. Experimental and theoretical investigations of four 3d-4f butterfly single-molecule magnets.

    PubMed

    Zou, Hua-Hong; Sheng, Liang-Bing; Liang, Fu-Pei; Chen, Zi-Lu; Zhang, Yi-Quan

    2015-11-14

    The syntheses, structures, and characterization of four 3d-4f butterfly clusters are described. With different polyhydroxy Schiff-base ligands 2-(((2-hydroxy-3-methoxyphenyl)methylene)amino)-2-(hydroxymethyl)-1,3-propanediol (H4L1) and 2-(2,3-dihydroxpropyliminomethyl)-6-methoxyphenol (H3L2), three heterotetranuclear NiLn complexes (NiDy-L1 (1), NiTb-L2 (2), NiDy-L2 (3)) and one heterohexanuclear CoDy complex (4) were obtained. The three heterotetranuclear NiLn complexes display a central planar butterfly topology. The heterohexanuclear complex was built from butterfly CoDy clusters and two Dy(III) ions by the bridging of pivalate. The vertices of the body positions of the butterfly are occupied by transition metal ions in all four complexes. Magnetic analyses indicate that the complexes exhibit typical single-molecule magnet behaviour with anisotropy barriers of 33.7 cm(-1), 60.3 cm(-1), 39.6 cm(-1), and 18.4 cm(-1) for 1-4, respectively. Ab initio calculations were performed on these complexes, and the low lying electronic structure of each Ln(III) (Ln = Dy, Tb) ion and the magnetic interactions were determined. It was found that the two Ln ions may have much more contribution to the total relaxation barrier through the stronger 3d-4f exchange couplings compared to weak Ln-Ln interactions. PMID:26443303

  11. Acoustic images of the submarine fan system of the northern Kumano Basin obtained during the experimental dives of the Deep Sea AUV URASHIMA

    NASA Astrophysics Data System (ADS)

    Kasaya, Takafumi; Kanamatsu, Toshiya; Sawa, Takao; Kinosita, Masataka; Tukioka, Satoshi; Yamamoto, Fujio

    2011-02-01

    Autonomous underwater vehicles (AUVs) present the important advantage of being able to approach the seafloor more closely than surface vessel surveys can. To collect bathymetric data, bottom material information, and sub-surface images, multibeam echosounder, sidescan sonar (SSS) and subbottom profiler (SBP) equipment mounted on an AUV are powerful tools. The 3000m class AUV URASHIMA was developed by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC). After finishing the engineering development and examination phase of a fuel-cell system used for the vehicle's power supply system, a renovated lithium-ion battery power system was installed in URASHIMA. The AUV was redeployed from its prior engineering tasks to scientific use. Various scientific instruments were loaded on the vehicle, and experimental dives for science-oriented missions conducted from 2006. During the experimental cruise of 2007, high-resolution acoustic images were obtained by SSS and SBP on the URASHIMA around the northern Kumano Basin off Japan's Kii Peninsula. The map of backscatter intensity data revealed many debris objects, and SBP images revealed the subsurface structure around the north-eastern end of our study area. These features suggest a structure related to the formation of the latest submarine fan. However, a strong reflection layer exists below ~20ms below the seafloor in the south-western area, which we interpret as a denudation feature, now covered with younger surface sediments. We continue to improve the vehicle's performance, and expect that many fruitful results will be obtained using URASHIMA.

  12. Assessment of the Stiffness of Major Salivary Glands in Primary Sjögren's Syndrome through Quantitative Acoustic Radiation Force Impulse Imaging.

    PubMed

    Zhang, Shanshan; Zhu, Jiaan; Zhang, Xia; He, Jing; Li, Jianguo

    2016-03-01

    The purpose of the study described here was to evaluate salivary gland stiffness in primary Sjögren's syndrome (pSS) via acoustic radiation force impulse imaging, including Virtual Touch tissue quantification (VTQ) and Virtual Touch tissue imaging quantification (VTIQ). Twenty-one patients with pSS and 11 healthy patients were included, and the paired parotid and submandibular glands of all of the patients were examined using VTQ and VTIQ. Differences between the two groups were compared with independent and paired t-tests. The VTQ value for the parotid in the pSS group was significantly higher than that obtained for the control group (1.33 ± 0.22 and 1.18 ± 0.04 m/s, respectively, p < 0.01). The VTIQ values for the parotid and submandibular gland were both significantly higher in the pSS group than in the control group (p < 0.05). In the pSS group, a positive correlation was observed between the VTQ and VTIQ results for the parotid and submandibular glands. In summary, the stiffness of the major salivary glands in patients with pSS was increased compared with that of patients with normal glands. This finding indicates that VTQ and VTIQ imaging may be valuable adjuncts to gray-scale ultrasonography for the clinical diagnosis of pSS. PMID:26715188

  13. System and method to create three-dimensional images of non-linear acoustic properties in a region remote from a borehole

    DOEpatents

    Vu, Cung; Nihei, Kurt T.; Schmitt, Denis P.; Skelt, Christopher; Johnson, Paul A.; Guyer, Robert; TenCate, James A.; Le Bas, Pierre-Yves

    2013-01-01

    In some aspects of the disclosure, a method for creating three-dimensional images of non-linear properties and the compressional to shear velocity ratio in a region remote from a borehole using a conveyed logging tool is disclosed. In some aspects, the method includes arranging a first source in the borehole and generating a steered beam of elastic energy at a first frequency; arranging a second source in the borehole and generating a steerable beam of elastic energy at a second frequency, such that the steerable beam at the first frequency and the steerable beam at the second frequency intercept at a location away from the borehole; receiving at the borehole by a sensor a third elastic wave, created by a three wave mixing process, with a frequency equal to a difference between the first and second frequencies and a direction of propagation towards the borehole; determining a location of a three wave mixing region based on the arrangement of the first and second sources and on properties of the third wave signal; and creating three-dimensional images of the non-linear properties using data recorded by repeating the generating, receiving and determining at a plurality of azimuths, inclinations and longitudinal locations within the borehole. The method is additionally used to generate three dimensional images of the ratio of compressional to shear acoustic velocity of the same volume surrounding the borehole.

  14. A single-sided homogeneous Green's function representation for holographic imaging, inverse scattering, time-reversal acoustics and interferometric Green's function retrieval

    NASA Astrophysics Data System (ADS)

    Wapenaar, Kees; Thorbecke, Jan; van der Neut, Joost

    2016-04-01

    Green's theorem plays a fundamental role in a diverse range of wavefield imaging applications, such as holographic imaging, inverse scattering, time-reversal acoustics and interferometric Green's function retrieval. In many of those applications, the homogeneous Green's function (i.e. the Green's function of the wave equation without a singularity on the right-hand side) is represented by a closed boundary integral. In practical applications, sources and/or receivers are usually present only on an open surface, which implies that a significant part of the closed boundary integral is by necessity ignored. Here we derive a homogeneous Green's function representation for the common situation that sources and/or receivers are present on an open surface only. We modify the integrand in such a way that it vanishes on the part of the boundary where no sources and receivers are present. As a consequence, the remaining integral along the open surface is an accurate single-sided representation of the homogeneous Green's function. This single-sided representation accounts for all orders of multiple scattering. The new representation significantly improves the aforementioned wavefield imaging applications, particularly in situations where the first-order scattering approximation breaks down.

  15. Acoustic emission

    NASA Astrophysics Data System (ADS)

    Straus, A.; Lopezpumarega, M. I.; Digaetano, J. O.; Datellis, C. E.; Ruzzante, J. E.

    This paper is related to our activities on acoustic emission (AE). At present, acoustic emission transducers are being developed for low and high temperature. A test to detect electrical discharges in electrical transformers was performed. Our experience in industrial tests in detecting cracks or failures in tanks or tubes is also described. The use of AE for leak detection is considered. Works on pattern recognition of AE signals are also being performed.

  16. Investigation of contact acoustic nonlinearity in delaminations by shearographic imaging, laser doppler vibrometric scanning and finite difference modeling.

    PubMed

    Sarens, Bart; Verstraeten, Bert; Glorieux, Christ; Kalogiannakis, Georgios; Van Hemelrijck, Danny

    2010-06-01

    Full-field dynamic shearography and laser Doppler vibrometric scanning are used to investigate the local contact acoustic nonlinear generation of delamination-induced effects on the vibration of a harmonically excited composite plate containing an artificial defect. Nonlinear elastic behavior caused by the stress-dependent boundary conditions at the delamination interfaces of a circular defect is also simulated by a 3-D second-order, finite-difference, staggered-grid model (displacement-stress formulation). Both the experimental and simulated data reveal an asymmetric motion of the layer above the delamination, which acts as a membrane vibrating with enhanced displacement amplitude around a finite offset displacement. The spectrum of the membrane motion is enriched with clapping-induced harmonics of the excitation frequency. In case of a sufficiently thin and soft membrane, the simulations reveal clear modal behavior at sub-harmonic frequencies caused by inelastic clapping. PMID:20529713

  17. Acoustic televiewer log images of natural fractures and bedding planes in the Toa Baja Borehole, Puerto Rico

    NASA Astrophysics Data System (ADS)

    Paillet, Frederick L.; Goldberg, David

    Although borehole conditions made acoustic televiewer logging difficult in the Toa Baja borehole, more than 180 meters of continuous, acceptable quality televiewer logs were obtained in the intervals from 730 to 880 meters and from 2,515 to 2,675 meters in depth, indicating the presence of fractures that appear to be open in situ. Most of the largest, possibly open fractures in these intervals are either nearly parallel to directions given by the dipmeter log and may represent solution openings or minor washouts along bedding planes, or dip steeply to the south or southwest across bedding. The televiewer log confirms the presence of an apparently open set of fractures near 867 meters in depth, where circulation was lost during drilling, and in the interval from 2,600 to 2,650 meters in depth, where the temperature log indicates anomalous heat flow in the surrounding formation.

  18. Acoustic televiewer log images of natural fractures and bedding planes in the Toa Baja borehole, Puerto Rico

    SciTech Connect

    Paillet, F.L.; Goldberg, D. )

    1991-03-01

    Although borehole conditions made acoustic televiewer logging difficult in the Toa Baja borehole, more than 180 meters of continuous, acceptable quality televiewer logs were obtained in the intervals from 730 to 880 meters and from 2,515 to 2,675 meters in depth, indicating the presence of fractures in these intervals are either nearly parallel to directions given by the dipmeter log and may represent solution openings or minor washouts along bedding planes, or dip steeply to the south or southwest across bedding. The televiewer log confirms the presence of an apparently open set of fractures near 867 meters in depth, where circulation was lost during drilling, and in the interval from 2,600 to 2,650 meters in depth, where the temperature log indicates anomalous heat flow in the surrounding formation.

  19. Acoustic emission linear pulse holography

    DOEpatents

    Collins, H. Dale; Busse, Lawrence J.; Lemon, Douglas K.

    1985-01-01

    Defects in a structure are imaged as they propagate, using their emitted acoustic energy as a monitored source. Short bursts of acoustic energy propagate through the structure to a discrete element receiver array. A reference timing transducer located between the array and the inspection zone initiates a series of time-of-flight measurements. A resulting series of time-of-flight measurements are then treated as aperture data and are transferred to a computer for reconstruction of a synthetic linear holographic image. The images can be displayed and stored as a record of defect growth.

  20. Acoustic emission linear pulse holography

    SciTech Connect

    Collins, H. D.; Busse, L. J.; Lemon, D. K.

    1985-07-30

    Defects in a structure are imaged as they propagate, using their emitted acoustic energy as a monitored source. Short bursts of acoustic energy propagate through the structure to a discrete element receiver array. A reference timing transducer located between the array and the inspection zone initiates a series of time-of-flight measurements. A resulting series of time-of-flight measurements are then treated as aperture data and are transferred to a computer for reconstruction of a synthetic linear holographic image. The images can be displayed and stored as a record of defect growth.

  1. XPS spectra of uranyl minerals and synthetic uranyl compounds. I: The U 4f spectrum

    NASA Astrophysics Data System (ADS)

    Schindler, M.; Hawthorne, F. C.; Freund, M. S.; Burns, P. C.

    2009-05-01

    The occurrence and binding energies of the U 6+, U 5+ and U 4+ bands in the U 4f 7/2 peak of 19 uranyl minerals of different composition and structure were measured by XPS. The results suggest that these minerals can be divided into the following four groups: (1) Uranyl-hydroxy-hydrate compounds with no or monovalent interstitial cations; (2) Uranyl-hydroxy-hydrate minerals with divalent interstitial cations; (3) Uranyl-oxysalt minerals with ( TO n) groups ( T = Si, P, and C) in which all equatorial O-atoms of the uranyl-polyhedra are shared with ( TO n) groups; (4) Uranyl-oxysalt minerals with ( TO n) groups ( T = S and Se), in which some equatorial O-atoms are shared only between uranyl polyhedra. The average binding energies of the U 6+and U 4+ bands shift to lower values with (1) incorporation of divalent cations and (2) increase in the Lewis basicity of the anion group bonded to U. The first observation is a consequence of an increase in the bond-valence transfer from the interstitial species (cations, H 2O) groups to the O-atoms of the uranyl-groups, which results in an electron transfer from O to U 6+. The second trend correlates with an increase in the covalency of the U sbnd O bonds with increase in Lewis basicity of the anion group, which results in a shift of the electron density from O to U. The presence of U 4+ on the surface of uranyl minerals can be detected by the shape of the U 4f 7/2 peak, and the occurrence of the U 5f peak and satellite peaks belonging to the U 4f 5/2 peak. The presence of U 4+ in some of the uranyl minerals and synthetics examined may be related to the conditions during their formation. A charge-balance mechanism is proposed for the incorporation of lower-valence U in the structure of uranyl minerals. Exposure of a Na-substituted metaschoepite crystal in air and to Ultra-High Vacuum results in dehydration of its surface structure associated with a shift of the U 6+ bands to higher binding energies. The latter observation indicates a shift in electron density from U to O, which must be related to structural changes inside the upper surface layers of Na-substituted metaschoepite.

  2. Effects of D-4F on vasodilation, oxidative stress, angiostatin, myocardial inflammation, and angiogenic potential in tight-skin mice.

    PubMed

    Weihrauch, Dorothee; Xu, Hao; Shi, Yang; Wang, Jingli; Brien, Jennifer; Jones, Deron W; Kaul, Sushma; Komorowski, Richard A; Csuka, Mary Ellen; Oldham, Keith T; Pritchard, Kirkwood A

    2007-09-01

    Systemic sclerosis (scleroderma, SSc) is an autoimmune, connective tissue disorder that is characterized by impaired vascular function, increased oxidative stress, inflammation of internal organs, and impaired angiogenesis. Tight skin mice (Tsk(-/+)) have a defect in fibrillin-1, resulting in replication of many of the myocardial and vascular features seen in humans with SSc. D-4F is an apolipoprotein A-I (apoA-I) mimetic that improves vascular function in diverse diseases such as hypercholesterolemia, influenza, and sickle cell disease. Tsk(-/+) mice were treated with either phosphate-buffered saline (PBS) or D-4F (1 mg.kg(-1).day(-1) for 6-8 wk). Acetylcholine and flow-induced vasodilation were examined in facialis arteries. Proinflammatory HDL (p-HDL) in murine and human plasma samples was determined by the cell-free assay. Angiostatin levels in murine and human plasma samples were determined by Western blot analysis. Hearts were examined for changes in angiostatin and autoantibodies against oxidized phosphotidylcholine (ox-PC). Angiogenic potential in thin sections of murine hearts was assessed by an in vitro vascular endothelial growth factor (VEGF)-induced endothelial cell (EC) tube formation assay. D-4F improved endothelium-, endothelial nitric oxide synthase-dependent, and flow-mediated vasodilation in Tsk(-/+) mice. Tsk(-/+) mice had higher plasma p-HDL and angiostatin levels than C57BL/6 mice, as did SSc patients compared with healthy control subjects. Tsk(-/+) mice also had higher triglycerides than C57BL/6 mice. D-4F reduced p-HDL, angiostatin, and triglycerides in the plasma of Tsk(-/+) mice. Tsk(-/+) hearts contained notably higher levels of angiostatin and autoantibodies against ox-PC than those of control hearts. D-4F ablated angiostatin in Tsk(-/+) hearts and reduced autoantibodies against ox-PC by >50% when compared with hearts from untreated Tsk(-/+) mice. Angiogenic potential in Tsk(-/+) hearts was increased only when the Tsk(-/+) mice were treated with D-4F (1 mg.kg(-1).day(-1), 6-8 wk), and cultured sections of hearts from the D-4F-treated Tsk(-/+) mice were incubated with D-4F (10 microg/ml, 5-7 days). Failure to treat the thin sections of hearts and Tsk(-/+) mice with D-4F resulted in loss of VEGF-induced EC tube formation. D-4F improves vascular function, decreases myocardial inflammation, and restores angiogenic potential in the hearts of Tsk(-/+) mice. As SSc patients have increased plasma p-HDL and angiostatin levels similar to the Tsk(-/+) mice, D-4F may be effective at treating vascular complications in patients with SSc. PMID:17496220

  3. Apolipoprotein A-I mimetic peptide L-4F prevents myocardial and coronary dysfunction in diabetic mice

    PubMed Central

    Vecoli, C.; Cao, J.; Neglia, D.; Inoue, K.; Sodhi, K.; Vanella, L.; Gabrielson, K. K.; Bedja, D.; Paolocci, N.; L'Abbate, A.; Abraham, N. G.

    2011-01-01

    Diabetes is a major health problem associated with adverse cardiovascular outcomes. The apolipoprotein A-I mimetic peptide L-4F is a putative anti-diabetic drug, has antioxidant and anti-inflammatory proprieties and improves endothelial function. In obese mice L-4F increases adiponectin levels, improving insulin sensitivity and reducing visceral adiposity. We hypothesized that the pleiotropic actions of L-4F can prevent heart and coronary dysfunction in a mouse model of genetically induced Type II diabetes. We treated db/db mice with either L-4F or vehicle for 8 weeks. Trans-thoracic echocardiography was performed; thereafter, isolated hearts were subjected to ischemia/reperfusion (IR). Glucose, insulin, adiponectin, and pro-inflammatory cytokines (IL-1?, TNF-?, MCP-1) were measured in plasma and HO-1, pAMPK, peNOS, iNOS, adiponectin and superoxide in cardiac tissue. In db/db mice L-4F decreased accumulation of subcutaneous and total fat, and increased insulin sensitivity and adiponectin levels while lowering inflammatory cytokines (p<0.05). L-4F normalized in vivo left ventricular (LV) function of db/db mice, increasing (p<0.05) fractional shortening and decreasing (p<0.05) LV dimensions. In I/R experiments, L-4F prevented coronary microvascular resistance from increasing and LV function from deteriorating in the db/db mice. These changes were associated with increased cardiac expression of HO-1, pAMPK, peNOS and adiponectin and decreased levels of superoxide and iNOS (p<0.01). In the present study we showed that L-4F prevented myocardial and coronary functional abnormalities in db/db mice. These effects were associated with stimulation of HO-1 resulting in increased levels of anti-inflammatory, anti-oxidative, and vasodilatatory action through a mechanism involving increased levels of adiponectin, pAMPK and peNOS. PMID:21598304

  4. 3d-4f magnetic interaction with density functional theory plus u approach: local Coulomb correlation and exchange pathways.

    PubMed

    Zhang, Yachao; Yang, Yang; Jiang, Hong

    2013-12-12

    The 3d-4f exchange interaction plays an important role in many lanthanide based molecular magnetic materials such as single-molecule magnets and magnetic refrigerants. In this work, we study the 3d-4f magnetic exchange interactions in a series of Cu(II)-Gd(III) (3d(9)-4f(7)) dinuclear complexes based on the numerical atomic basis-norm-conserving pseudopotential method and density functional theory plus the Hubbard U correction approach (DFT+U). We obtain improved description of the 4f electrons by including the semicore 5s5p states in the valence part of the Gd-pseudopotential. The Hubbard U correction is employed to treat the strongly correlated Cu-3d and Gd-4f electrons, which significantly improve the agreement of the predicted exchange constants, J, with experiment, indicating the importance of accurate description of the local Coulomb correlation. The high efficiency of the DFT+U approach enables us to perform calculations with molecular crystals, which in general improve the agreement between theory and experiment, achieving a mean absolute error smaller than 2 cm(-1). In addition, through analyzing the physical effects of U, we identify two magnetic exchange pathways. One is ferromagnetic and involves an interaction between the Cu-3d, O-2p (bridge ligand), and the majority-spin Gd-5d orbitals. The other one is antiferromagnetic and involves Cu-3d, O-2p, and the empty minority-spin Gd-4f orbitals, which is suppressed by the planar Cu-O-O-Gd structure. This study demonstrates the accuracy of the DFT+U method for evaluating the 3d-4f exchange interactions, provides a better understanding of the exchange mechanism in the Cu(II)-Gd(III) complexes, and paves the way for exploiting the magnetic properties of the 3d-4f compounds containing lanthanides other than Gd. PMID:24274078

  5. A Preliminary Engineering Design of Intravascular Dual-Frequency Transducers for Contrast-Enhanced Acoustic Angiography and Molecular Imaging

    PubMed Central

    Ma, Jianguo; Martin, K. Heath; Dayton, Paul A.; Jiang, Xiaoning

    2014-01-01

    Current intravascular ultrasound (IVUS) probes are not optimized for contrast detection because of their design for high-frequency fundamental-mode imaging. However, data from transcutaneous contrast imaging suggests the possibility of utilizing contrast ultrasound for molecular imaging or vasa vasorum assessment to further elucidate atherosclerotic plaque deposition. This paper presents the design, fabrication, and characterization of a small-aperture (0.6 3 mm) IVUS probe optimized for high-frequency contrast imaging. The design utilizes a dual-frequency (6.5 MHz/30 MHz) transducer arrangement for exciting microbubbles at low frequencies (near their resonance) and detecting their broadband harmonics at high frequencies, minimizing detected tissue backscatter. The prototype probe is able to generate nonlinear microbubble response with more than 1.2 MPa of rarefractional pressure (mechanical index: 0.48) at 6.5 MHz, and is also able to detect microbubble response with a broadband receiving element (center frequency: 30 MHz, ?6-dB fractional bandwidth: 58.6%). Nonlinear super-harmonics from microbubbles flowing through a 200-?m-diameter micro-tube were clearly detected with a signal-to-noise ratio higher than 12 dB. Preliminary phantom imaging at the fundamental frequency (30 MHz) and dual-frequency super-harmonic imaging results suggest the promise of small aperture, dual-frequency IVUS transducers for contrast-enhanced IVUS imaging. PMID:24801226

  6. Conduction band states and the 5d-4f laser transition of rare earth ion dopants

    SciTech Connect

    Payne, S.A.; Marshall, C.D.; Bayramian, A.; Lawson, J.K.

    1996-12-31

    We discuss how the interactions of the 5d orbital with the conduction band of the host medium play a crucial role in determining whether rare earth containing materials can serve as useful laser materials, based on their 5d-4f transition. To explore this issue, we examine the pump-probe spectra of Sm[sup 2+], Eu[sup 2+], and Ce[sup 3+] dopants in various fluoride and chloride crystals. In addition we suggest that the luminescence properties are also profoundly impacted by this interaction. The outstanding UV laser performance achieved by the Ce:LiSrAlF[sub 6] crystal is rationalized in terms of the reduced overlap of conduction band states with the cerium ions.

  7. Magnetism and superconductivity driven by identical 4f states in a heavy-fermion metal

    SciTech Connect

    Thompson, Joe E; Nair, S; Stockert, O; Witte, U; Nicklas, M; Schedler, R; Bianchi, A; Fisk, Z; Wirth, S; Steglich, K

    2009-01-01

    The apparently inimical relationship between magnetism and superconductivity has come under increasing scrutiny in a wide range of material classes, where the free energy landscape conspires to bring them in close proximity to each other. Particularly enigmatic is the case when these phases microscopically interpenetrate, though the manner in which this can be accomplished remains to be fully comprehended. Here, we present combined measurements of elastic neutron scattering, magnetotransport, and heat capacity on a prototypical heavy fermion system, in which antiferromagnetism and superconductivity are observed. Monitoring the response of these states to the presence of the other, as well as to external thermal and magnetic perturbations, points to the possibility that they emerge from different parts of the Fermi surface. Therefore, a single 4f state could be both localized and itinerant, thus accounting for the coexistence of magnetism and superconductivity.

  8. Surface and bulk 4f-photoemission spectra of CeIn{sub 3} and CeSn{sub 3}

    SciTech Connect

    Kim, H.; Tjernberg, O.; Chiaia, G.; Kumigashira, H.; Takahashi, T.; Duo, L.; Sakai, O.; Kasaya, M.; Lindau, I.

    1997-07-01

    Resonant photoemission spectroscopy was performed on CeIn{sub 3} and CeSn{sub 3} at the 4d-4f and 3d-4f core thresholds. Using the different surface sensitivity between the two photon energies, surface and bulk 4f-photoemission spectra were derived for both compounds. With the noncrossing approximation of the Anderson impurity model, the 4d-4f resonant spectra together with the surface and bulk spectra were self-consistently analyzed to obtain the microscopic parameters such as the 4f-electron energy and the hybridization strength with conduction electrons. The result shows a substantial difference in these parameters between the surface and the bulk, indicating that it is important to take into account the surface effect in analyzing photoemission spectra of Ce compounds. It is also found that the 4f surface core-level shift is different between CeIn{sub 3} and CeSn{sub 3}. {copyright} {ital 1997} {ital The American Physical Society}

  9. Fluorination of diamond C 4F 9I and CF 3I photochemistry on diamond (100)

    NASA Astrophysics Data System (ADS)

    Smentkowski, Vincent S.; Yates, John T.; Chen, Xiaojie; Goddard, William A.

    1997-01-01

    The radiation-induced decomposition of C 4F 9I and CF 3I overlayers at 119 K on diamond (100) surfaces has been shown to be an efficient route to fluorination of the diamond surface. X-ray photoelectron spectroscopy has been used for photoactivation as well as for studying the photodecomposition of the fluoroalkyl iodide molecules, the attachment of the photofragments to the diamond surface, and the thermal decomposition of the fluoroalkyl ligands. Measured chemical shifts agree well with ab initio calculations of both C 1s and F 1s binding energies. It is found that chemisorbed CF 3 groups on diamond (100) decompose by 300 K whereas C 4F 9 groups decompose over the range 300 to 700 K and this reactivity difference is rationalized on steric grounds. Both of these thermal decomposition processes produce surface C?F bonds on the diamond. The surface C?F species thermally decompose over a wide temperature range extending up to 1500 K. Hydrogen passivation of the diamond surface is ineffective in preventing free radical attack from the photodissociated products of the fluoroalkyl iodides; I atoms produced photolytically abstract H from surface C?H bonds to yield hydrogen iodide at 119 K allowing diamond fluorination. The attachment of chemisorbed F species to the diamond (100) surface causes band bending as the surface states are occupied as a result of chemisorption. This results in a shift to higher binding energy of the diamond-related C 1s levels present in the surface and subsurface regions which are sampled by XPS on the diamond. The use of photoactivation of fluoroalkyl iodides for the fluorination of diamond surfaces provides a convenient route compared to other methods involving the action of atomic F, molecular F 2, XeF 2 and F-containing plasmas.

  10. 4f heavy fermion photoelectron spectra do not exhibit the Kondo scale

    SciTech Connect

    Arko, A.J.; Joyce, J.J.; Andrews, A.B.; Blyth, R.I.R.; Bartlett, R.J.; Fisk, Z.; Canfield, P.C.; Olson, C.G.; Benning, P.J.; Poirier, D.M.; Weaver, J.H.; Riseborough, P.S.

    1994-02-01

    It has been the authors contention for some time that the Single Impurity Anderson Model (SIAM), as extended by Gunnarsson and Schonhammer (GS), or the non-crossing approximation (NCA), does not correctly describe the 4f photoelectron spectra of heavy fermions. Recently, they have concentrated on Yb heavy fermions since in these materials the Kondo resonance (KR) is fully occupied and thus accessible via photoemission. In particular, they have repeatedly pointed out that the width, position, spectral weight, lineshape, and temperature dependence of the features assumed to be the KR and its sidebands, are nearly independent of the Kondo temperature, T{sub K}, while at the same time bearing a striking resemblance to the simple 4f core level spectra of pure Yb metal, or of Lu in isostructural Lu compounds. It is important to resolve these issues in view of the fundamental nature of the problem. Here, the authors chose to test the bulk vs. surface hypothesis by performing measurements on YbCu{sub 2}Si{sub 2} and YbAl{sub 3} single crystals at hv {approx} 120 eV (UPS) and hv {approx} 1,500 eV(XPS) to see if the n{sub f}, hole occupancy, values increase markedly at XPS energies as the electron escape depth increases by about a factor of 3--5. Measurements were performed at both 300K and 20K using single crystals cleaved in-situ, with photoelectrons collected in normal emission for maximum bulk sensitivity. UPS measurements were performed at NSLS and the University of Wisconsin SRC, while XPS measurements were done at the University of Minnesota. The UPS, ultraviolet photoelectron spectra, and the L{sub III} edge x-ray absorption and photoemission measurements are in fundamental disagreement.

  11. Small-Scale Trial for Evaluating Directional Resolution of Single Spherical Biconcave Acoustic Lens in Designing of Ambient Noise Imaging System

    NASA Astrophysics Data System (ADS)

    Mori, Kazuyoshi; Ogasawara, Hanako; Nakamura, Toshiaki

    2008-05-01

    Ambient noise imaging (ANI) is the revolutionary idea of detecting objects by using natural ocean background noise. From the analysis results obtained by the finite difference time domain (FDTD) method in our previous studies, it was supposed that a spherical biconcave lens with an aperture diameter of 2.0 m has a sufficient directional resolution (for example, the beam width is 1 at 60 kHz) for realizing an ANI system. In this study, to confirm the analysis results, we performed a small-scale trial of one-fifth space in a water tank. The lens, made of acrylic resin, has an aperture diameter of 400 mm and a radius of curvature of 500 mm. A burst pulse of 25 cycles at 300 kHz, whose frequency increases 5 times, was radiated from the sound source. The sound pressure after passage through the acoustic lens was measured by moving the receiver around the image point. Results show that the shapes of -3 dB areas are similar to the FDTD analysis results at small incidence angles. It was verified that this lens has a sufficient directional resolution for use in the ANI system, because -3 dB areas do not overlap each other.

  12. Optimization of Contrast-to-Tissue Ratio Through Pulse Windowing in Dual-Frequency "Acoustic Angiography" Imaging.

    PubMed

    Lindsey, Brooks D; Shelton, Sarah E; Dayton, Paul A

    2015-07-01

    Early-stage tumors in many cancers are characterized by vascular remodeling, indicative of transformations in cell function. We have previously presented a high-resolution ultrasound imaging approach to detecting these changes that is based on microbubble contrast agents. In this technique, images are formed from only the higher harmonics of microbubble contrast agents, producing images of vasculature alone with 100- to 200-?m resolution. In this study, shaped transmit pulses were used to image the higher broadband harmonic echoes of microbubble contrast agents, and the effects of varying pulse window and phasing on microbubble and tissue harmonic echoes were evaluated using a dual-frequency transducer in vitro and in vivo. An increase in the contrast-to-tissue ratio of 6.8 2.3 dB was observed in vitro using an inverted pulse with a cosine window relative to a non-inverted pulse with a rectangular window. The increase in mean image intensity resulting from contrast enhancement in vivo in five rodents was 13.9 3.0 dB greater for an inverted cosine-windowed pulse and 17.8 3.6 dB greater for a non-inverted Gaussian-windowed pulse relative to a non-inverted pulse with a rectangular window. Implications for pre-clinical and diagnostic imaging are discussed. PMID:25819467

  13. Section and stroboscopic diffraction imaging of the magneto-acoustic vibrations in FeBO3 by synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Matsouli, Ioanna; Pernot, Etienne; Baruchel, José; Kvardakov, Vladimir; Chabert, Laurent; Palmer, Stuart B.

    1999-05-01

    Ultrasonic waves, excited in an FeBO3 crystal via magneto-elastic coupling, were visualized using synchrotron radiation diffraction imaging (`topography'). In particular, restricted volume images were used in order to distinguish the contribution of the various parts of a thin (50 µm) sample to the diffracted beam. The magnetic field dependence of the sound velocity was then exploited to tune the FeBO3 crystal at a resonance four times the ESRF single bunch frequency, allowing stroboscopic section imaging and the deconvolution of the time-integration effect. This set of experiments confirmed that the vibrating crystal model used to explain the focusing of x-rays in FeBO3 at certain resonances is correct.

  14. Measurements of electron transport coefficients in the 0.468% and 4.91% c-C4F8/Ar mixtures and pure c-C4F8

    NASA Astrophysics Data System (ADS)

    Yamaji, Masahiro; Nakamura, Yoshiharu

    2000-10-01

    This report presents the results of the electron drift velocity (W), the product of the gas number density and the longitudinal diffusion coefficient (ND_L), and the attachment coefficient (?/N) over the range 0.74F_8/Ar mixture, the range 104F_8/Ar mixture, and the range 2004F_8. Measurements were carried out by using the double shutter drift tube with variable drift distance [J.Phys.D30, 1610 (1991)]. These values of mixture are compared with the calculated values which is derived from the cross section set of Itoh [J.Phys.D:Appl.Phys.24, 277 (1991)]. The calculated values are higher than the measured values at low E/N range. This fact shows that the cross section set must be improved. The method of calculation is the Boltzmann's multi-term approximation, but we found that this method is not applied well to c-C_4F_8, because the NDL values at low E/N range are unstable. The measured pure c-C_4F8 results of W are compared with the measured values of Naidu [J.Phys.D5, 741 (1972)], and the difference between these data is apparent at high E/N range.

  15. Comparative 4f-4f absorption spectral study for the interactions of Nd(III) with some amino acids: Preliminary thermodynamics and kinetic studies of interaction of Nd(III):glycine with Ca(II)

    NASA Astrophysics Data System (ADS)

    Moaienla, T.; Bendangsenla, N.; David Singh, Th.; Sumitra, Ch.; Rajmuhon Singh, N.; Indira Devi, M.

    2012-02-01

    Spectral analysis of Nd(III) complexes with some amino acids viz.; glycine, L-alanine, L-phenylalanine and L-aspartic acid in the presence and absence of Ca 2+ was carried out in some organic solvents; CH 3OH, CH 3CN, DMF and dioxane using comparative absorption spectra of 4f-4f transitions. The study was carried out by evaluating various energy interaction parameters like Slator-Condon ( Fk), Lande factor ( ?4f), nephelauxetic ratio ( ?), bonding parameter ( b1/2), percent-covalency ( ?) by applying partial and multiple regression analysis. The values of oscillator strength ( Pobs) and Judd-Ofelt electric dipole intensity parameter T? ( ? = 2, 4, 6) for different 4f-4f transitions have been calculated. On analysis of the variation of the various energy interaction parameters as well as the changes in the oscillator strength ( Pobs) and T? values, reveal the mode of binding with the different ligands. Kinetic studies for the complexation of Nd(III):glycine:Ca(II) have also been discussed at different temperatures in DMF medium and from it the values of activation energy ( Ea) and thermodynamic parameters like ? H, ? S and ? G for the complexation are evaluated.

  16. Comparative 4f-4f absorption spectral study for the interactions of Nd(III) with some amino acids: Preliminary thermodynamics and kinetic studies of interaction of Nd(III):glycine with Ca(II).

    PubMed

    Moaienla, T; Bendangsenla, N; David Singh, Th; Sumitra, Ch; Rajmuhon Singh, N; Indira Devi, M

    2012-02-15

    Spectral analysis of Nd(III) complexes with some amino acids viz.; glycine, l-alanine, l-phenylalanine and l-aspartic acid in the presence and absence of Ca(2+) was carried out in some organic solvents; CH(3)OH, CH(3)CN, DMF and dioxane using comparative absorption spectra of 4f-4f transitions. The study was carried out by evaluating various energy interaction parameters like Slator-Condon (F(k)), Lande factor (?(4f)), nephelauxetic ratio (?), bonding parameter (b(1/2)), percent-covalency (?) by applying partial and multiple regression analysis. The values of oscillator strength (P(obs)) and Judd-Ofelt electric dipole intensity parameter T(?) (?=2, 4, 6) for different 4f-4f transitions have been calculated. On analysis of the variation of the various energy interaction parameters as well as the changes in the oscillator strength (P(obs)) and T(?) values, reveal the mode of binding with the different ligands. Kinetic studies for the complexation of Nd(III):glycine:Ca(II) have also been discussed at different temperatures in DMF medium and from it the values of activation energy (E(a)) and thermodynamic parameters like ?H, ?S and ?G for the complexation are evaluated. PMID:22169029

  17. Use of the 4F Roesch Inferior Mesenteric Catheter in Embolization Procedures in the Pelvis: A Review of 300 Cases

    SciTech Connect

    Kroencke, Thomas J. Kluner, Claudia; Hamm, Bernd; Gauruder-Burmester, Annett

    2007-04-15

    The aim of this study is to evaluate the use of a 4F Roesch inferior mesenteric (RIM) catheter for pelvic embolization procedures. Between October 2000 and January 2006, 364 patients (357 female, 7 male; age: 23-67 years) underwent embolization of various pathologies [uterine fibroids (n = 324), pure adenomyosis of the uterus (n = 19), postpartum hemorrhage (n =1), traumatic or postoperative hemorrhage (n = 9), bleeding related to cervical cancer (n =7), AV malformation of the uterus (n = 2) and high-flow priapism (n = 2)] at a single institution. In all cases, bilateral catheterization was primarily attempted with the use of a 4F hook-shaped braided endhole catheter (Roesch-Inferior-Mesenteric, RIM-Catheter, Cordis, Miami, FL). Frequency of initial failure to catheterize the vascular territory of interest and carry out the embolization were recorded and the types of difficulty encountered were noted. Catherization of the main stem of the vessel territory of interest with the use of a unilateral femoral approach and the 4F RIM catherer was successful in 334/364 (91.8%) the embolization cases. Bilateral catheterization of the internal iliac arteries using a single common femoral artery access and the 4F RIM catheter was achieved in 322/364 (88.5%) patients. In 12/364 (3.3%) patients, a contralateral puncture was performed and the same 4F catheter was used. In 28/364 (7.7%) cases the 4F RIM catheter was exchanged for a catheter with a cobra-shaped or sidewinder configuration. The 4F RIM catheter is a simple and valuable alternative to catheters and techniques commonly employed for pelvic artery embolization.

  18. Regulation of the Orphan Nuclear Receptor Nr2f2 by the DFNA15 Deafness Gene Pou4f3

    PubMed Central

    Tornari, Chrysostomos; Towers, Emily R.; Gale, Jonathan E.; Dawson, Sally J.

    2014-01-01

    Hair cells are the mechanotransducing cells of the inner ear that are essential for hearing and balance. POU4F3 a POU-domain transcription factor selectively expressed by these cells has been shown to be essential for hair cell differentiation and survival in mice and its mutation in humans underlies late-onset progressive hearing loss (DFNA15). The downstream targets of POU4F3 are required for hair cell differentiation and survival. We aimed to identify such targets in order to elucidate the molecular pathways involved in hair cell production and maintenance. The orphan thyroid nuclear receptor Nr2f2 was identified as a POU4F3 target using a subtractive hybridization strategy and EMSA analysis showed that POU4F3 binds to two sites in the Nr2f2 5? flanking region. These sites were shown to be required for POU4F3 activation as their mutation leads to a reduction in the response of an Nr2f2 5? flanking region reporter construct to POU4F3. Immunocytochemistry was carried out in the developing and adult inner ear in order to investigate the relevance of this interaction in hearing. NR2F2 expression in the postnatal mouse organ of Corti was shown to be detectable in all sensory epithelia examined and characterised. These data demonstrate that Nr2f2 is a direct target of POU4F3 in vitro and that this regulatory relationship may be relevant to hair cell development and survival. PMID:25372459

  19. Altered Leukotriene B4 metabolism in CYP4F18-deficient mice does not impact inflammation following renal ischemia

    PubMed Central

    Winslow, Valeria; Vaivoda, Rachel; Vasilyev, Aleksandr; Dombkowski, David; Douaidy, Karim; Stark, Christopher; Drake, Justin; Guilliams, Evin; Choudhary, Dharamainder; Preffer, Frederic; Stoilov, Ivaylo; Christmas, Peter

    2014-01-01

    Inflammatory responses to infection and injury must be restrained and negatively regulated to minimize damage to host tissue. One proposed mechanism involves enzymatic inactivation of the pro-inflammatory mediator leukotriene B4, but it is difficult to dissect the roles of various metabolic enzymes and pathways. A primary candidate for a regulatory pathway is omega oxidation of leukotriene B4 in neutrophils, presumptively by CYP4F3A in humans and CYP4F18 in mice. This pathway generates ω, ω-1, and ω-2 hydroxylated products of leukotriene B4, depending on species. We created mouse models targeting exons 8 and 9 of the Cyp4f18 allele that allows both conventional and conditional knockout of Cyp4f18. Neutrophils from wild-type mice convert leukotriene B4 to 19-hydroxy leukotriene B4, and to a lesser extent 18-hydroxy leukotriene B4, whereas these products were not detected in neutrophils from conventional Cyp4f18 knockouts. A mouse model of renal ischemia-reperfusion injury was used to investigate the consequences of loss of CYP4F18 in vivo. There were no significant changes in infiltration of neutrophils and other leukocytes into kidney tissue as determined by flow cytometry and immunohistochemistry, or renal injury as assessed by histological scoring and measurement of blood urea nitrogen. It is concluded that CYP4F18 is necessary for omega oxidation of leukotriene B4 in neutrophils, and is not compensated by other CYP enzymes, but loss of this metabolic pathway is not sufficient to impact inflammation and injury following renal ischemia-reperfusion in mice. PMID:24632148

  20. Controlling sound with acoustic metamaterials

    NASA Astrophysics Data System (ADS)

    Cummer, Steven A.; Christensen, Johan; Alù, Andrea

    2016-03-01

    Acoustic metamaterials can manipulate and control sound waves in ways that are not possible in conventional materials. Metamaterials with zero, or even negative, refractive index for sound offer new possibilities for acoustic imaging and for the control of sound at subwavelength scales. The combination of transformation acoustics theory and highly anisotropic acoustic metamaterials enables precise control over the deformation of sound fields, which can be used, for example, to hide or cloak objects from incident acoustic energy. Active acoustic metamaterials use external control to create effective material properties that are not possible with passive structures and have led to the development of dynamically reconfigurable, loss-compensating and parity–time-symmetric materials for sound manipulation. Challenges remain, including the development of efficient techniques for fabricating large-scale metamaterial structures and converting laboratory experiments into useful devices. In this Review, we outline the designs and properties of materials with unusual acoustic parameters (for example, negative refractive index), discuss examples of extreme manipulation of sound and, finally, provide an overview of future directions in the field.

  1. Acoustic Inversion in Optoacoustic Tomography: A Review

    PubMed Central

    Rosenthal, Amir; Ntziachristos, Vasilis; Razansky, Daniel

    2013-01-01

    Optoacoustic tomography enables volumetric imaging with optical contrast in biological tissue at depths beyond the optical mean free path by the use of optical excitation and acoustic detection. The hybrid nature of optoacoustic tomography gives rise to two distinct inverse problems: The optical inverse problem, related to the propagation of the excitation light in tissue, and the acoustic inverse problem, which deals with the propagation and detection of the generated acoustic waves. Since the two inverse problems have different physical underpinnings and are governed by different types of equations, they are often treated independently as unrelated problems. From an imaging standpoint, the acoustic inverse problem relates to forming an image from the measured acoustic data, whereas the optical inverse problem relates to quantifying the formed image. This review focuses on the acoustic aspects of optoacoustic tomography, specifically acoustic reconstruction algorithms and imaging-system practicalities. As these two aspects are intimately linked, and no silver bullet exists in the path towards high-performance imaging, we adopt a holistic approach in our review and discuss the many links between the two aspects. Four classes of reconstruction algorithms are reviewed: time-domain (so called back-projection) formulae, frequency-domain formulae, time-reversal algorithms, and model-based algorithms. These algorithms are discussed in the context of the various acoustic detectors and detection surfaces which are commonly used in experimental studies. We further discuss the effects of non-ideal imaging scenarios on the quality of reconstruction and review methods that can mitigate these effects. Namely, we consider the cases of finite detector aperture, limited-view tomography, spatial under-sampling of the acoustic signals, and acoustic heterogeneities and losses. PMID:24772060

  2. [Architectural acoustics].

    PubMed

    Ullmann, Dieter

    2006-01-01

    This paper discusses the development of architectural acoustics from Sabine's paper (1900) to the beginning of computer simulation. In the 20th century, physicists have dominated this field, but the problems to be solved require an interdisciplinary approach involving physicists, musicians, and architects. PMID:16929793

  3. Acoustic Images of Submarine landslide in western Sagami Bay obtained by deep sea AUV URASHIMA in Sagami bay

    NASA Astrophysics Data System (ADS)

    Kasaya, Takafumi; Tsukioka, Satoshi; Yamamoto, Fujio; Hyakudome, Tadahiro; Sawa, Takao; Yoshida, Hiroshi; Ishibashi, Shojiro; Tahara, Junichiro; Kinoshita, Masataka; Aoki, Taro

    To collect bathymetric data and bottom material information, multi narrow beam echo sounder and/or side scan sonar are usually used over wide area. The autonomous underwater vehicle (AUV) has the advantage of getting closer to the sea surface as compared with a survey from the vessel. URASHIMA is a 3000 m class AUV, is loaded with multi narrow beam depth sounder, side scan sonar and sub-bottom profiler. Using URASHIMA, side scan sonar images and sub-bottom profiles were collected around off Hatsushima Island where mud flow was generated with some large earthquakes occurrence. We could obtain many enough quality side scan sonar images and sub-bottom profiles. Mosaic image was constructed by obtained side scan sonar images, and shows distinctive surface structure. Some irregular patches are detected around the mudflow area 7km off Hatsushima Island. This structure do not relate to the bathymetry obtained by SeaBat8160 on R/V Natsushima. Therefore, these are interpreted as debris generated with earthquakes. Sub-bottom profiles could detect very clear sedimentary structure.

  4. The Electronegativity Analysis of c-C4F8 as a Potential Insulation Substitute of SF6

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaoling; Jiao, Juntao; Li, Bing; Xiao, Dengming

    2016-03-01

    The density distributions related to gas electronegativity for c-C4F8 gas, including negative ion, electron number and electron energy densities in the discharge process, are derived theoretically in both plane-to-plane and point-to-plane electrode geometries. These calculations have been performed through the Boltzmann equation in the condition of a steady-state Townsend (SST) experiment and a fluid model in the condition of both uniform and non-uniform electric fields. The electronegativity coefficients a = n‑/ne of c-C4F8 and SF6 are compared to further describe the electron affinity of c-C4F8. The result shows that c-C4F8 represents an obvious electron-attachment performance in the discharge process. However, c-C4F8 still has much weaker gas electronegativity than SF6, whose electronegativity coefficient is lower than that of SF6 by at least three orders of magnitude. supported by National Natural Science Foundation of China (No. 51337006)

  5. Two transcription factors, Pou4f2 and Isl1, are sufficient to specify the retinal ganglion cell fate

    PubMed Central

    Wu, Fuguo; Kaczynski, Tadeusz J.; Sethuramanujam, Santhosh; Li, Renzhong; Jain, Varsha; Slaughter, Malcolm; Mu, Xiuqian

    2015-01-01

    As with other retinal cell types, retinal ganglion cells (RGCs) arise from multipotent retinal progenitor cells (RPCs), and their formation is regulated by a hierarchical gene-regulatory network (GRN). Within this GRN, three transcription factorsatonal homolog 7 (Atoh7), POU domain, class 4, transcription factor 2 (Pou4f2), and insulin gene enhancer protein 1 (Isl1)occupy key node positions at two different stages of RGC development. Atoh7 is upstream and is required for RPCs to gain competence for an RGC fate, whereas Pou4f2 and Isl1 are downstream and regulate RGC differentiation. However, the genetic and molecular basis for the specification of the RGC fate, a key step in RGC development, remains unclear. Here we report that ectopic expression of Pou4f2 and Isl1 in the Atoh7-null retina using a binary knockin-transgenic system is sufficient for the specification of the RGC fate. The RGCs thus formed are largely normal in gene expression, survive to postnatal stages, and are physiologically functional. Our results indicate that Pou4f2 and Isl1 compose a minimally sufficient regulatory core for the RGC fate. We further conclude that during development a core group of limited transcription factors, including Pou4f2 and Isl1, function downstream of Atoh7 to determine the RGC fate and initiate RGC differentiation. PMID:25775587

  6. Effects of feedstock availability on the negative ion behavior in a C4F8 inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Zhao, Shu-Xia; Gao, Fei; Wang, Ya-Ping; Wang, You-Nian; Bogaerts, Annemie

    2015-07-01

    In this paper, the negative ion behavior in a C4F8 inductively coupled plasma (ICP) is investigated using a hybrid model. The model predicts a non-monotonic variation of the total negative ion density with power at low pressure (10-30 mTorr), and this trend agrees well with experiments that were carried out in many fluorocarbon (fc) ICP sources, like C2F6, CHF3, and C4F8. This behavior is explained by the availability of feedstock C4F8 gas as a source of the negative ions, as well as by the presence of low energy electrons due to vibrational excitation at low power. The maximum of the negative ion density shifts to low power values upon decreasing pressure, because of the more pronounced depletion of C4F8 molecules, and at high pressure (50 mTorr), the anion density continuously increases with power, which is similar to fc CCP sources. Furthermore, the negative ion composition is identified in this paper. Our work demonstrates that for a clear understanding of the negative ion behavior in radio frequency C4F8 plasma sources, one needs to take into account many factors, like the attachment characteristics, the anion composition, the spatial profiles, and the reactor configuration. Finally, a detailed comparison of our simulation results with experiments is conducted.

  7. Association of the CYP4F2 rs2108622 genetic polymorphism with hypertension: a meta-analysis.

    PubMed

    Luo, X-H; Li, G-R; Li, H-Y

    2015-01-01

    Previous case-control studies on the relationship between the CYP4F2 gene rs2108622 polymorphism and hypertension have produced contrasting results. In this study, we aimed to further evaluate the relationship between the CYP4F2 gene rs2108622 polymorphism and hypertension. We selected four case-control studies related to the CYP4F2 gene rs2108622 polymorphism and hypertension by searching PubMed, EMBase, the Chinese Biomedical Literature Database, and the Wanfang database. We utilized the Cochran Q-test and the I2 index to measure the heterogeneity across studies. To merge the odds ratio (OR) and the 95% confidence interval (95%CI), we utilized the fixed and random-effect models during the analyses. The present study included 1878 patients with hypertension and 1512 healthy control subjects. By meta-analysis, we did not find any association of the CYP4F2 gene rs2108622 polymorphism with hypertension in either genotype or allele distribution [AA+AG vs GG: OR = 1.18, 95%CI (0.91-1.54), P = 0.21; GG+AG vs AA: OR = 0.91, 95%CI (0.80-1.05), P = 0.20; A allele vs G allele: OR = 1.04, 95%CI (0.93-1.16), P = 0.53]. We concluded that the CYP4F2 gene rs2108622 polymorphism was not associated with hypertension. PMID:26634476

  8. Acoustic Characterization of Mesoscale Objects

    SciTech Connect

    Chinn, D; Huber, R; Chambers, D; Cole, G; Balogun, O; Spicer, J; Murray, T

    2007-03-13

    This report describes the science and engineering performed to provide state-of-the-art acoustic capabilities for nondestructively characterizing mesoscale (millimeter-sized) objects--allowing micrometer resolution over the objects entire volume. Materials and structures used in mesoscale objects necessitate the use of (1) GHz acoustic frequencies and (2) non-contacting laser generation and detection of acoustic waves. This effort demonstrated that acoustic methods at gigahertz frequencies have the necessary penetration depth and spatial resolution to effectively detect density discontinuities, gaps, and delaminations. A prototype laser-based ultrasonic system was designed and built. The system uses a micro-chip laser for excitation of broadband ultrasonic waves with frequency components reaching 1.0 GHz, and a path-stabilized Michelson interferometer for detection. The proof-of-concept for mesoscale characterization is demonstrated by imaging a micro-fabricated etched pattern in a 70 {micro}m thick silicon wafer.

  9. The VMI study on angular distribution of ejected electrons from Eu 4f76p1/26d autoionizing states

    NASA Astrophysics Data System (ADS)

    Zhang, Kai; Shen, Li; Dong, Cheng; Dai, Chang-Jian

    2015-10-01

    The combination of a velocity mapping imaging technique and mathematical transformation is adopted to study the angular distribution of electrons ejected from the Eu 4f76p1/26d autoionizing states, which are excited with a three-step excitation scheme via different Eu 4f76s6d 8 DJ (J = 5/2, 7/2, and 9/2) intermediate states. In order to determine the energy dependence of angular distribution of the ejected electrons, the anisotropic parameters are measured in the spectral profile of the 6p1/26d autoionizing states by tuning the wavelength of the third-step laser across the ionic resonance lines of the Eu 6s+ ? 6p+. The configuration interaction is discussed by comparing the angular distributions of ejected electrons from the different states. The present study reveals the profound variations of anisotropic parameters in the entire region of autoionization resonance, highlighting the complicated nature of the autoionization process for the lowest member of 6p1/26d autoionization series. Project supported by the National Natural Science Foundation of China (Grant No. 11174218).

  10. The function of the Periaxin gene during nerve repair in a model of CMT4F.

    PubMed

    Williams, Anna C; Brophy, Peter J

    2002-04-01

    Mutations in the Periaxin (PRX) gene are known to cause autosomal recessive demyelinating Charcot-Marie-Tooth (CMT4F) and Dejerine-Sottas disease. The pathogenesis of these diseases is not fully understood. However, progress is being made by studying both the periaxin-null mouse, a mouse model of the disease, and the protein-protein interactions of periaxin. L-periaxin is a constituent of the dystroglycan-dystrophin-related protein-2 complex linking the Schwann cell cytoskeleton to the extracellular matrix. Although periaxin-null mice myelinate normally, they develop a demyelinating peripheral neuropathy later in life. This suggests that periaxin is required for the stable maintenance of a normal myelin sheath. We carried out sciatic nerve crushes in 6-week-old periaxin-null mice, and, 6 weeks later, found that although the number of myelinated axons had returned to normal, the axon diameters remained smaller than in the contralateral uncrushed nerve. Not only do periaxin-null mice have more hyper-myelinated axons than their wild-type counterparts but they also recapitulate this hypermyelination during regeneration. Therefore, periaxin-null mice can undergo peripheral nerve remyelination, but the regulation of peripheral myelin thickness is disrupted. PMID:12090399

  11. The extreme ultraviolet emissions of W23+(4f5)

    NASA Astrophysics Data System (ADS)

    Pütterich, T.; Jonauskas, V.; Neu, R.; Dux, R.; ASDEX Upgrade Team

    2013-07-01

    In order to comply with the special challenges (open 4f-shell, configuration mixing) of simulating the spectrum of W23+ an extensive atomic model was implemented using the flexible atomic code (FAC). In detail, the basis functions from 11 configurations were used to model about 12000 levels, which give rise to roughly 60 million transitions including nearly 6 million electric and magnetic dipole transitions. A collisional radiative model has been put together which could handle the size of the input data. The modelled spectra (4-40 nm) show low sensitivity on the electron density, which validates the comparison of EBIT and tokamak spectra. The emissions between 4 and 7 nm are discussed in the context of the observations at fusion plasmas. In this range, the influence of W23+ is limited due to the small contribution to the measurement - however, elements of the presented modelling might explain the second, not understood spectral feature at 6 nm. Further details of the spectra are only briefly discussed as a close comparison to experimental data requires also models for the neighbouring ionisation stages. Additionally, the importance of configuration mixing becomes apparent motivating further investigations on neighbouring ionisation stages with similarly complex models.

  12. Pressure-enhanced superconductivity in Eu3Bi2S4F4

    DOE PAGESBeta

    Luo, Yongkang; Zhai, Hui -Fei; Zhang, Pan; Xu, Zhu -An; Cao, Guang -Han; Thompson, J. D.

    2014-12-17

    The pressure effect on the newly discovered charge-transferred BiS2-based superconductor, Eu3Bi2S4F4, with a Tc of 1.5 K at ambient pressure, is investigated by transport and magnetic measurements. Accompanied with the enhancement of metallicity under pressures, the onset superconducting transition temperature increases abruptly around 1.0 GPa, reaching ~10.0 K at 2.26 GPa. Alternating current magnetic susceptibility measurements indicate that a new superconducting phase with a higher Tc emerges and dominates at high pressures. In the broad pressure window of 0.68GPa≤p≤2.00 GPa, the high-Tc phase coexists with the low-Tc phase. Hall effect measurements reveal a significant difference in electronic structures between themore » two superconducting phases. As a result, our work devotes the effort to establish the commonality of pressure effect on the BiS2-based superconductors, and also uncovers the importance of electron carrier density in the high-Tc phase.« less

  13. Synthesis and Characterization of La 3NbSe 2O 4F 2

    NASA Astrophysics Data System (ADS)

    Brennan, Theodore D.; Mansuetto, Michael F.; Ibers, James A.

    1993-12-01

    Crystals of the unusual oxyfluoroselenide La 3NbSe 2O 4F 2 were obtained during the exploration of the quaternary La/Nb/Cu/Se system. Oxygen was extracted from the silica tube, while fluorine was present as a minor impurity in the La powder. The compound crystallizes in space group D 162 h- Pnma of the orthorhombic system with four formula units in a cell with dimensions: a = 11.290(4), b = 4.001(1), and c = 18.062(4) ( T = 113 K). The structure has been determined by single-crystal X-ray methods. The presence of F in the crystals was confirmed by windowless EDAX measurements. The two F sites were distinguished from the four O sites from a combination of the X-ray refinement and a bond-valence parameter calculation made with the program EUTAX. In the structure the Nb atom is octahedrally coordinated while each of the three independent La atoms is in a tricapped trigonal prism. The Nb atom is bound to one Se atom and five O atoms while the three La sites are coordinated by various combinations of Se, O, and F atoms. The NbO 5Se octahedra corner share and the LaSe xO yF z tricapped trigonal prisms face share in the b direction.

  14. Theoretical study of the CH4+F --> CH3+FH reaction. II. Semiempirical surfaces

    NASA Astrophysics Data System (ADS)

    Corchado, J. C.; Espinosa-Garca, J.

    1996-08-01

    We present two semiempirical surfaces for the CH4+F?CH3+FH reaction. One is based on the PM3 semiempirical molecular orbital theory, using parameters specifically calculated for this reaction (SRP method), and the other is based on the analytic function J1 for the CH4+H?CH3+H2 reaction, slightly modified (MJ1 surface). To calibrate the first surface we chose as reference data the reactant and product experimental properties, while to fit the second, we also used ab initio calculated saddle-point information. Experimental rate constants were not used in the calibration because of their uncertainty. Because of the flattening of these surfaces in the saddle-point zone, the variational effects are important and the location of the transition state is concluded to be due to entropy effects. The kinetic isotope effects (KIEs) at different temperatures were also analyzed showing reasonable agreement with the experimental value for both surfaces. The factor analysis of the KIEs indicates an inverse tunneling contribution originated by the behavior of the VGa curve. The strengths and the weaknesses of these two surfaces, along with the ab initio reaction path studied previously, were also analyzed.

  15. A Search for EUV Emission from the O4f Star Zeta Puppis

    NASA Technical Reports Server (NTRS)

    Waldron, Wayne L.; Vallerga, John

    1996-01-01

    We obtained a 140 ks EUVE observation of the O4f star, zeta Puppis. Because of its low ISM column density and highly ionized stellar wind, a unique EUV window is accessible for viewing between 128 to 140 A, suggesting that this star may he the only O star observable with the EUVE. Although no SW spectrometer wavelength bin had a signal to noise greater than 3, a bin at 136 A had a signal to noise of 2.4. This bin is where models predict the brightest line due to OV emission should occur. We present several EUV line emission models. These models were constrained by fitting the ROSAT PSPC X-ray data and our EUVE data. If the OV emission is real, the best fits to the data suggest that there are discrepancies in our current understanding of EUV/X-ray production mechanisms. In particular, the emission measure of the EUV source is found to be much greater than the total wind emission measure, suggesting that the EUV shock must produce a very large density enhancement. In addition, the location of the EUV and X-ray shocks are found to be separated by approx. 0.3 stellar radii, but the EUV emission region is found to be approx. 400 times larger than the X-ray emission region. We also discuss the implications of a null detection and present relevant upper limits.

  16. Acoustic transducer for acoustic microscopy

    DOEpatents

    Khuri-Yakub, B.T.; Chou, C.H.

    1990-03-20

    A shear acoustic transducer-lens system is described in which a shear polarized piezoelectric material excites shear polarized waves at one end of a buffer rod having a lens at the other end which excites longitudinal waves in a coupling medium by mode conversion at selected locations on the lens. 9 figs.

  17. Acoustic transducer for acoustic microscopy

    DOEpatents

    Khuri-Yakub, Butrus T.; Chou, Ching H.

    1990-01-01

    A shear acoustic transducer-lens system in which a shear polarized piezoelectric material excites shear polarized waves at one end of a buffer rod having a lens at the other end which excites longitudinal waves in a coupling medium by mode conversion at selected locations on the lens.

  18. Results of magnetic resonance imaging assessment, acoustic analysis, phonatory function and perceptual rating of glottic insufficiency before and after fat augmentation: correlated with subjective rating.

    PubMed

    Hsiung, Ming-Wang; Chen, Yen-Yu; Pai, Lu; Lin, Chao-Jung; Wang, Hsing-Won

    2003-01-01

    Autogenous fat augmentation has been proven effective in the treatment of glottic insufficiency (GI) using both subjective and objective methods of evaluation. However, no information is available in published research regarding the effectiveness and predictability of value parameters with regard to patients' perceptions and concerns. This article retrospectively examines the correlation between subjective and objective examinations and subjective ratings (SRs) in patients with presbylaryngis (n = 14) and sulcus vocalis (n = 2). Acoustic analysis, phonatory function, magnetic resonance imaging (MRI) assessment, and perceptual rating data were evaluated against SRs using pre- and postoperative test results in 16 patients. The mean time over which subjective and objective examinations were performed was 10 months. Twelve patients reported excellent results, while no change was observed in 4 patients. When compared against SR, the kappa value of jitter, shimmer, harmonic to noise ratio, phonation time, grade, roughness, breathiness, and MRI were 0.25, 0, -0.08, -0.11, -0.11, 0.18, 0, and 1, respectively. The agreement between the MRI and SR values was complete, and was the only relationship shown to be significant (p < 0.001). MRI assessment is an effective and reliable examination tool which can be considered for use in assessing the progress of the post-fat injection operation in GI patients during follow-up examinations. Furthermore, due to the excellent agreement between MRI assessment and the patients' subjective feelings, the SR value may serve as a good index of fat survival. PMID:12824728

  19. Evaluation of Transient Elastography, Acoustic Radiation Force Impulse Imaging (ARFI), and Enhanced Liver Function (ELF) Score for Detection of Fibrosis in Morbidly Obese Patients

    PubMed Central

    Karlas, Thomas; Dietrich, Arne; Peter, Veronica; Wittekind, Christian; Lichtinghagen, Ralf; Garnov, Nikita; Linder, Nicolas; Schaudinn, Alexander; Busse, Harald; Prettin, Christiane; Keim, Volker; Trltzsch, Michael; Schtz, Tatjana; Wiegand, Johannes

    2015-01-01

    Background Liver fibrosis induced by non-alcoholic fatty liver disease causes peri-interventional complications in morbidly obese patients. We determined the performance of transient elastography (TE), acoustic radiation force impulse (ARFI) imaging, and enhanced liver fibrosis (ELF) score for fibrosis detection in bariatric patients. Patients and Methods 41 patients (median BMI 47 kg/m2) underwent 14-day low-energy diets to improve conditions prior to bariatric surgery (day 0). TE (M and XL probe), ARFI, and ELF score were performed on days -15 and -1 and compared with intraoperative liver biopsies (NAS staging). Results Valid TE and ARFI results at day -15 and -1 were obtained in 49%/88% and 51%/90% of cases, respectively. High skin-to-liver-capsule distances correlated with invalid TE measurements. Fibrosis of liver biopsies was staged as F1 and F3 in n = 40 and n = 1 individuals. However, variations (median/range at d-15/-1) of TE (4.6/2.675 and 6.7/2.921.3 kPa) and ARFI (2.1/0.73.7 and 2.0/0.73.8 m/s) were high and associated with overestimation of fibrosis. The ELF score correctly classified 87.5% of patients. Conclusion In bariatric patients, performance of TE and ARFI was poor and did not improve after weight loss. The ELF score correctly classified the majority of cases and should be further evaluated. PMID:26528818

  20. Evaluation of damage accumulation behavior and strength anisotropy of NITE SiC/SiC composites by acoustic emission, digital image correlation and electrical resistivity monitoring

    NASA Astrophysics Data System (ADS)

    Nozawa, Takashi; Ozawa, Kazumi; Asakura, Yuuki; Kohyama, Akira; Tanigawa, Hiroyasu

    2014-12-01

    Understanding the cracking process of the composites is essential to establish the design basis for practical applications. This study aims to investigate the damage accumulation process and its anisotropy for nano-infiltration transient eutectic sintered (NITE) SiC/SiC composites by various characterization techniques such as the acoustic emission (AE), digital image correlation (DIC) and electrical resistivity (ER) measurements. Cracking behavior below the proportional limit stress (PLS) was specifically addressed. Similar to the other generic SiC/SiC composites, the 1st AE event was identified below the PLS for NITE SiC/SiC composites with a dependency of fabric orientation. The DIC results support that the primary failure mode depending on fiber orientation affected more than the other minor modes did. Detailed AE waveform analysis by wavelet shows a potential to classify the failure behavior depending on architecture. Cracking below the PLS is a potential concern in component deign but the preliminary ER measurements imply that the impact of cracking below the PLS on composite function was limited.

  1. A 4F2-cross-point phase change memory using nano-crystalline doped GeSbTe material

    NASA Astrophysics Data System (ADS)

    Takaura, Norikatsu; Kinoshita, Masaharu; Tai, Mitsuharu; Ohyanagi, Takasumi; Akita, Kenichi; Morikawa, Takahiro

    2015-04-01

    This paper reports on the use of nano-crystalline doped GeSbTe, or nano-GST, to fabricate a cross-point phase change memory with 4F2 cell size and test results obtained for it. We show the characteristics of a poly-Si diode select device with a high on-off ratio and data writing in a 4F2 memory cell array. The advantages of nano-GST over conventional GeSbTe are presented in terms of neighboring disturbance and 4F2 cross-point array formation. The memory cells’ high drivability, low power, and selective write and read performances are demonstrated. The scalability of the diode current density is also presented.

  2. Cryogenic etching processes applied to porous low-k materials using SF6/C4F8 plasmas

    NASA Astrophysics Data System (ADS)

    Leroy, F.; Zhang, L.; Tillocher, T.; Yatsuda, K.; Maekawa, K.; Nishimura, E.; Lefaucheux, P.; de Marneffe, J.-F.; Baklanov, M. R.; Dussart, R.

    2015-11-01

    Cryogenic etching processes in SF6 and SF6/C4F8 plasmas were successfully applied to porous organosilicate glasses. Such materials are low-k candidates for advanced interconnects. Their integration is very challenging because of plasma induced damage. These two chemistries (SF6 and SF6/C4F8) have demonstrated a promising capability of significantly reducing the damage caused by plasma etching. Desorbed species were analyzed during the wafer warm-up from cryogenic to room temperature by in situ mass spectrometry. An equivalent damage layer (EDL) was evaluated by ex situ Fourier transform infrared (FTIR) spectroscopy and in situ ellipsometry. An anneal step at 350 °C seems efficient to completely desorb the remaining CF x species. Anisotropic profiles were obtained using both chemistries. The selectivity is enhanced using SF6/C4F8 process at low temperature.

  3. Non-intrusive telemetry applications in the oilsands: from visible light and x-ray video to acoustic imaging and spectroscopy

    NASA Astrophysics Data System (ADS)

    Shaw, John M.

    2013-06-01

    While the production, transport and refining of oils from the oilsands of Alberta, and comparable resources elsewhere is performed at industrial scales, numerous technical and technological challenges and opportunities persist due to the ill defined nature of the resource. For example, bitumen and heavy oil comprise multiple bulk phases, self-organizing constituents at the microscale (liquid crystals) and the nano scale. There are no quantitative measures available at the molecular level. Non-intrusive telemetry is providing promising paths toward solutions, be they enabling technologies targeting process design, development or optimization, or more prosaic process control or process monitoring applications. Operation examples include automated large object and poor quality ore during mining, and monitoring the thickness and location of oil water interfacial zones within separation vessels. These applications involve real-time video image processing. X-ray transmission video imaging is used to enumerate organic phases present within a vessel, and to detect individual phase volumes, densities and elemental compositions. This is an enabling technology that provides phase equilibrium and phase composition data for production and refining process development, and fluid property myth debunking. A high-resolution two-dimensional acoustic mapping technique now at the proof of concept stage is expected to provide simultaneous fluid flow and fluid composition data within porous inorganic media. Again this is an enabling technology targeting visualization of diverse oil production process fundamentals at the pore scale. Far infrared spectroscopy coupled with detailed quantum mechanical calculations, may provide characteristic molecular motifs and intermolecular association data required for fluid characterization and process modeling. X-ray scattering (SAXS/WAXS/USAXS) provides characteristic supramolecular structure information that impacts fluid rheology and process fouling. The intent of this contribution is to present some of the challenges and to provide an introduction grounded in current work on non-intrusive telemetry applications - from a mine or reservoir to a refinery!

  4. Implementation and Comparison of Acoustic Travel-Time Measurement Procedures for the Helioseismic and Magnetic Imager Time-Distance Helioseismology Pipeline

    NASA Technical Reports Server (NTRS)

    Couvidat, S.; Zhao, J.; Birch, A. C.; Kosovichev, A. G.; Duvall, T. L., Jr.; Parchevsky, K.; Scherrer, P. H.

    2009-01-01

    The Helioseismic and Magnetic Imager (HMI) instrument on board the Solar Dynamics Observatory (SDO) satellite is designed to produce high-resolution Doppler velocity maps of oscillations at the solar surface with high temporal cadence. To take advantage of these high-quality oscillation data, a time-distance helioseismology pipeline has been implemented at the Joint Science Operations Center (JSOC) at Stanford University. The aim of this pipeline is to generate maps of acoustic travel times from oscillations on the solar surface, and to infer subsurface 3D flow velocities and sound-speed perturbations. The wave travel times are measured from cross covariances of the observed solar oscillation signals. For implementation into the pipeline we have investigated three different travel-time definitions developed in time-distance helioseismology: a Gabor wavelet fitting (Kosovichev and Duvall, 1997), a minimization relative to a reference cross-covariance function (Gizon and Birch, 2002), and a linearized version of the minimization method (Gizon and Birch, 2004). Using Doppler velocity data from the Michelson Doppler Imager (MDI) instrument on board SOHO, we tested and compared these definitions for the mean and difference travel-time perturbations measured from reciprocal signals. Although all three procedures return similar travel times in a quiet Sun region, the method of Gizon and Birch (2004) gives travel times that are significantly different from the others in a magnetic (active) region. Thus, for the pipeline implementation we chose the procedures of Kosovichev and Duvall (1997) and Gizon and Birch (2002). We investigated the relationships among these three travel-time definitions, their sensitivities to fitting parameters, and estimated the random errors they produce

  5. Implementation and Comparison of Acoustic Travel-Time Measurement Procedures for the Solar Dynamics Observatory-Helioseismic and Magnetic Imager Time-Distance Helioseismology Pipeline

    NASA Technical Reports Server (NTRS)

    Couvidat, S.; Zhao, J.; Birch, A. C.; Kosovichev, A. G.; Duvall, Thomas L., Jr.; Parchevsky, K.; Scherrer, P. H.

    2010-01-01

    The Helioseismic and Magnetic Imager (HMI) instrument onboard the Solar Dynamics Observatory (SDO) satellite is designed to produce high-resolution Doppler-velocity maps of oscillations at the solar surface with high temporal cadence. To take advantage of these high-quality oscillation data, a time - distance helioseismology pipeline (Zhao et al., Solar Phys. submitted, 2010) has been implemented at the Joint Science Operations Center (JSOC) at Stanford University. The aim of this pipeline is to generate maps of acoustic travel times from oscillations on the solar surface, and to infer subsurface 3D flow velocities and sound-speed perturbations. The wave travel times are measured from cross-covariances of the observed solar oscillation signals. For implementation into the pipeline we have investigated three different travel-time definitions developed in time - distance helioseismology: a Gabor-wavelet fitting (Kosovichev and Duvall, SCORE'96: Solar Convection and Oscillations and Their Relationship, ASSL, Dordrecht, 241, 1997), a minimization relative to a reference cross-covariance function (Gizon and Birch, Astrophys. J. 571, 966, 2002), and a linearized version of the minimization method (Gizon and Birch, Astrophys. J. 614, 472, 2004). Using Doppler-velocity data from the Michelson Doppler Imager (MDI) instrument onboard SOHO, we tested and compared these definitions for the mean and difference traveltime perturbations measured from reciprocal signals. Although all three procedures return similar travel times in a quiet-Sun region, the method of Gizon and Birch (Astrophys. J. 614, 472, 2004) gives travel times that are significantly different from the others in a magnetic (active) region. Thus, for the pipeline implementation we chose the procedures of Kosovichev and Duvall (SCORE'96: Solar Convection and Oscillations and Their Relationship, ASSL, Dordrecht, 241, 1997) and Gizon and Birch (Astrophys. J. 571, 966, 2002). We investigated the relationships among these three travel-time definitions, their sensitivities to fitting parameters, and estimated the random errors that they produce.

  6. Acoustic imaging of the passage of turbidity currents and associated hydraulic jumps on underlying cyclic step bedforms. Squamish, BC

    NASA Astrophysics Data System (ADS)

    Hughes Clarke, J. E.

    2013-12-01

    Active channelized turbidity currents have been repeatedly imaged in 60m of water on the Squamish prodelta. Previously in 2011 and 2012, the prodelta has been repetitively surveyed on daily and hourly timescales and is thus known to exhibit trains of bedforms along the channel floors that resemble cyclic steps that migrate upslope intermittently. Beyond the channel mouths, clear turbidity current flows had previously been detected using a seabed mounted ADCP. In order to directly observe the passage of the flow in the channelized section of the prodelta, in June 2013 a vessel was moored using 4 anchors directly above one of the channels. The vessel operated two hull-mounted single beam sonars at 28 and 200 kHz and a multibeam sonar at 95 kHz, all imaging a near stationary point or swath within or across the channel. In addition a 1200 kHz ADCP was suspended 12m above the seabed and two 500 kHz imaging multibeams were suspended 10m above the channel floor. One of the suspended multibeams was oriented facing upslope examining a 150m range, 120 degree, plan view sector of the channel. The second suspended multibeam was oriented downward to derive a ~30m long along-track section over the length of one of the bedforms. A mechanically dipped CTD and optical backscatter probe was lower repeatedly directly into the active flows until it touched the seabed at about one minute periods. Over a period of 5 days, between 1 and 7 discrete flows per day were monitored passing by within one hour of low water. Their head velocities ranged from ~ 0.5 to 2.5m/s and their thicknesses were generally in the 3-5m range. Looking upstream in plan view, the lobate head of the approaching flows could be seen to be constricted to specific talwegs within the channel floor and rise up and over successive cyclic step bedforms. The higher velocity flows exhibit clear turbulent eddies on their upper surface. The duration of the high velocity component of the flow rarely lasted for more than a few minutes. For the two highest velocity flows observed, a clear hydraulic jump could be seen in the suspended multibeam imagery just downstream of the base of the stoss face of the imaged bedform. The hull mounted sonars clearly reveal massive release of gas from the seabed in the wake of the head passage. Bathymetric surface differences from surveys from the preceding and following high tide period indicated multiple active feeder channels descending from the lip of the delta.

  7. Assignment of 4f->5d excitation spectra of Nd{sup 3+} in crystals using the simple model

    SciTech Connect

    Xia Shangda; Duan Changkui . E-mail: duanck@cqupt.edu.cn; Deng Quan; Ruan Gang

    2005-09-15

    The measured low-temperature (4f){sup 3}->(4f){sup 2}5d excitation spectra of Nd{sup 3+} doped in crystals YPO{sub 4}, CaF{sub 4} and LiYF{sub 4} [van Pieterson et al., Phys. Rev. B 65 (2002) 045113] are assigned and analyzed using the simple model proposed by Duan et al. [Phys. Rev. B 66 (2002) 155108] and Ning et al. [J. Alloy. Compd. 366 (2004) 34]. The agreement between theoretical and observed energies and intensities are acceptable, and at the same time the spectra are assigned in more detail.

  8. 3D-Seismic and Acoustic Imaging of Gas Migration and Gas Hydrate Accumulations Beneath Pockmarks in Hemipelagic Sediments off Congo, SW Africa

    NASA Astrophysics Data System (ADS)

    Spiess, V.; Zhlsdorff, L.; Seifert, A.; Hirsch, K.

    2004-12-01

    Seismic and acoustic imaging is a major tool to study basic geological parameters controlling the occurrence of gas hydrate as well as of free gas within the gas hydrate stability field. For sufficient upward fluxes of hydrocarbon gases, gas hydrates grow within pore spaces or gases are trapped beneath efficient seals, thereby revealing information about the nature and efficiency of fluid flow pathways and about the time scale on which fluid transport occurs. In the hemipelagic sedimentary sequences off the Congo, where layering and uniform properties exist at the time of deposition, modification of sediment physical properties due to mixing between water, gas and hydrates within pore spaces affects amplitude and phase properties of seismic reflections. Furthermore, fluid flow and gas or hydrate accumulations are often associated with sediment deformation or faulting on different scales. Thus, an integrated interpretation of seismic, acoustic, and surface mapping data sets was used to optimize lateral and vertical resolution at each depth level and to connect deeper processes to their surface expressions. 3D seismic data across seafloor pockmarks indicate that the typical low-amplitude signature of opal-rich and water-rich sediments is superimposed by high amplitude zones near faults and potential fluid pathways. A high amplitude patch observed in 40-50 m depth is interpreted as a gas hydrate cap that plugs the feeder channel of a pockmark and initiates hydrate growth parallel to the bedding. The upflow zone at greater depth is characterized by amplitude blanking, indicating free gas bubbles that scatter seismic energy. A package of high amplitude reflector elements at 150-200 m sub-bottom depth suggests the presence of trapped gas beneath a low permeable layer. This package is bent upwards at the vicinity of the pockmark, probably indicating a deeper salt diapir, that is associated with faulting and probably higher permeability above the diapir. However, the creation of pathways beneath the pockmarks is not yet completely understood. Preliminary results based on 3D mapping of fault plane orientations suggest that faulting due to diapirism may be superimposed by zones of weakness within a regional fault pattern that probably is of polygonal structure.

  9. Acoustic chaos

    SciTech Connect

    Lauterborn, W.; Parlitz, U.; Holzfuss, J.; Billo, A.; Akhatov, I.

    1996-06-01

    Acoustic cavitation, a complex, spatio-temporal dynamical system, is investigated with respect to its chaotic properties. The sound output, the {open_quote}{open_quote}noise{close_quote}{close_quote}, is subjected to time series analysis. The spatial dynamics of the bubble filaments is captured by high speed holographic cinematography and subsequent digital picture processing from the holograms. Theoretical models are put forward for describing the pattern formation. {copyright} {ital 1996 American Institute of Physics.}

  10. Cyclo-octafluorobutane (PFC-318, c-C4F8) in the global atmosphere

    NASA Astrophysics Data System (ADS)

    Muhle, J.; Vollmer, M. K.; Ivy, D. J.; Fraser, P.; Arnold, T.; Harth, C. M.; Salameh, P.; O'Doherty, S.; Young, D.; Steele, P.; Krummel, P. B.; Leist, M.; Rhee, T. S.; Schmidbauer, N.; Lunder, C.; Kim, J.; Kim, K.; Reimann, S.; Simmonds, P.; Prinn, R. G.; Weiss, R. F.

    2011-12-01

    The perfluorocarbon (PFC) cyclo-octafluorobutane (PFC-318, c-C4F8) is a very long-lived (up to 3,200 years) and potent greenhouse gas (100-year global warming potential up to 10,300) with a wide range of industrial uses. We present an update of our PFC-318 archived air and in situ measurements from remote and urban AGAGE (Advanced Global Atmospheric Gases Experiment) sites and affiliated stations in both hemispheres. Most importantly, we have significantly improved our Southern Hemisphere (SH) data density by measuring the Cape Grim Air Archive (1970s-2010). Combined with our previously presented measurements of archived Northern Hemisphere (NH) flasks (1973-2009), we provide thirty year spanning records for both hemispheres. We have also further extended our in situ records by continuing our measurements at all remote stations, with the longest hemispheric records starting in November 2007 at Jungfraujoch (NH) and in June 2010 at Cape Grim (SH). We compare our data with those of Oram (1999) and Oram et al. (2011), who focus on SH data alone, and with other previous data sets. From our measurements, we derive emission estimates using a chemical transport model and inverse method, and compare our results to previous measurement based emission estimates (top-down) and to the EDGAR emission database (bottom-up). As stated previously (Mhle et al., 2010), we find emissions of ~1 Gg/yr in recent years while EDGAR estimates only 0.02 Gg/yr for 2005, similar to what Oram et al. (2011) find. We conclude that PFC-318 is the third most important PFC in terms of abundance and CO2-equivalent emissions. We continue to observe mostly baseline concentrations at remote AGAGE stations and urban sites in the USA, Europe, and Australia, in contrast to frequent pollution episodes measured at sites in East Asia, indicating significant regional emissions in East Asia, as found by Saito et al. (2010). EDGAR, Emission Database for Global Atmospheric Research, release version 4.1. http://edgar.jrc.ec.europa.eu, last accessed 2011. Mhle et al., Cyclo-octafluorobutane (PFC-318) in the global atmosphere, Abstract A51D-0143, AGU Fall Meeting, San Francisco, CA, 13-17 Dec., 2010. Oram, Trends of long-lived anthropogenic halocarbons in the Southern Hemisphere and model calculation of global emissions, Ph.D. thesis, University of East Anglia, Norwich, U.K., 1999. Oram et al., Long-term tropospheric trend of octafluorocyclobutane (c-C4F8 or PFC-318), Atmos. Chem. Phys. Discuss., 11, 7, 19089-19111, 10.5194/acpd-11-19089-2011, 2011. Saito et al., Large Emissions of Perfluorocarbons in East Asia Deduced from Continuous Atmospheric Measurements, Environ. Sci. Technol., 44(11), 4089-4095, doi:10.1021/es1001488, 2010.

  11. Expression and characterization of human cytochrome P450 4F11: Putative role in the metabolism of therapeutic drugs and eicosanoids.

    PubMed

    Kalsotra, Auinash; Turman, Cheri M; Kikuta, Yasushi; Strobel, Henry W

    2004-09-15

    We previously reported the cDNA cloning of a new CYP4F isoform, CYP4F11. In the present study, we have expressed CYP4F11 in Saccharomyces cerevisiae and examined its catalytic properties towards endogenous eicosanoids as well as some clinically relevant drugs. CYP4F3A, also known as a leukotriene B4 omega-hydroxylase, was expressed in parallel for comparative purposes. Our results show that CYP4F11 has a very different substrate profile than CYP4F3A. CYP4F3A metabolized leukotriene B4, lipoxins A4 and B4, and hydroxyeicosatetraenoic acids (HETEs) much more efficiently than CYP4F11. On the other hand, CYP4F11 was a better catalyst than CYP4F3A for many drugs such as erythromycin, benzphetamine, ethylmorphine, chlorpromazine, and imipramine. Erythromycin was the most efficient substrate for CYP4F11, with a Km of 125 microM and Vmax of 830 pmol min(-1) nmol(-1) P450. Structural homology modeling of the two proteins revealed some interesting differences in the substrate access channel including substrate recognition site 2 (SRS2). The model of CYP4F11 presents a more open access channel that may explain the ability to metabolize large molecules like erythromycin. Also, some wide variations in residue size, charge, and hydrophobicity in the FG loop region may contribute to differences in substrate specificity and activity between CYP4F3A and CYP4F11. PMID:15364545

  12. Etching of porous and solid SiO{sub 2} in Ar/c-C{sub 4}F{sub 8}, O{sub 2}/c-C{sub 4}F{sub 8} and Ar/O{sub 2}/c-C{sub 4}F{sub 8} plasmas

    SciTech Connect

    Sankaran, Arvind; Kushner, Mark J.

    2005-01-15

    C-C{sub 4}F{sub 8}-based plasmas are used for selective etching of high aspect ratio (HAR) trenches in SiO{sub 2} and other dielectrics for microelectronics fabrication. Additives such as Ar and O{sub 2} are often used to optimize the process. Understanding the fundamentals of these processes is critical to extending technologies developed for solid SiO{sub 2} to porous SiO{sub 2}, as used in low-dielectric constant insulators. To investigate these issues, reaction mechanisms developed for etching of solid and porous SiO{sub 2} in fluorocarbon plasmas and for etching of organic polymers in O{sub 2} plasmas have been incorporated into a feature profile model capable of addressing two-phase porous materials. The reaction mechanism was validated by comparison to experiments for blanket etching of solid and porous SiO{sub 2} in Ar/c-C{sub 4}F{sub 8} and O{sub 2}/c-C{sub 4}F{sub 8} plasmas using inductively coupled plasma reactors. We found that the blanket etch rates of both solid and porous SiO{sub 2} had maxima as a function of Ar and O{sub 2} addition to c-C{sub 4}F{sub 8} at mole fractions corresponding to an optimum thickness of the overlying polymer layer. Larger Ar and O{sub 2} additions were required to optimize the etch rate for porous SiO{sub 2}. Whereas etch stops occurred during etching of HAR features in solid and porous SiO{sub 2} using pure c-C{sub 4}F{sub 8} plasmas, Ar and O{sub 2} addition facilitated etching by reducing the polymer thickness, though with some loss of critical dimensions. Mixtures of Ar/O{sub 2}/c-C{sub 4}F{sub 8} can be used to manage this tradeoff.

  13. PSpice circuital modelling of ultrasonic imaging transceivers including frequency-dependent acoustic losses and signal distortions in electronic stages.

    PubMed

    Ramos, A; Ruz, A; San Emeterio, J L; Sanz, P T

    2006-12-22

    A new global circuital model is proposed taking into account some piezoelectric and electronic non-ideal aspects of the broadband ultrasonic transceivers used in NDT and imaging applications. A quadratic approach, alternative to previous linear Spice implementations, is proposed for the frequency dependence of the mechanical losses into the piezoelectric sections. Non-ideal frequency-dependent electrical effects influencing excitation circuitry performance, and attenuations in the propagation medium varying with frequency, are also considered. Results calculated, by using PSpice implementations, from conventional and the new modelling approaches show how the quadratic option to calculate losses clearly reduces the rippled and sharpened waveforms typically originated in many echo-signals simulations, and which are not observed in real measured responses. Experimental waveforms for driving spikes and for echo-signals, in very good agreement with responses simulated from the new modelling here proposed, are also shown. PMID:16797653

  14. Lithium transition metal fluorophosphates (Li{sub 2}CoPO{sub 4}F and Li{sub 2}NiPO{sub 4}F) as cathode materials for lithium ion battery from atomistic simulation

    SciTech Connect

    Lee, Sanghun Park, Sung Soo

    2013-08-15

    Lithium transition metal fluorophosphates (Li{sub 2}MPO{sub 4}F, M: Co and Ni) have been investigated from atomistic simulation. In order to predict the characteristics of these materials as cathode materials for lithium ion batteries, structural property, defect chemistry, and Li{sup +} ion transportation property are characterized. The core–shell model with empirical force fields is employed to reproduce the unit-cell parameters of crystal structure, which are in good agreement with the experimental data. In addition, the formation energies of intrinsic defects (Frenkel and antisite) are determined by energetics calculation. From migration energy calculations, it is found that these flurophosphates have a 3D Li{sup +} ion diffusion network forecasting good Li{sup +} ion conducting performances. Accordingly, we expect that this study provides an atomic scale insight as cathode materials for lithium ion batteries. - Graphical abstract: Lithium transition metal fluorophosphates (Li{sub 2}CoPO{sub 4}F and Li{sub 2}NiPO{sub 4}F). Display Omitted - Highlights: • Lithium transition metal fluorophosphates (Li{sub 2}MPO{sub 4}F, M: Co and Ni) are investigated from classical atomistic simulation. • The unit-cell parameters from experimental studies are reproduced by the core–shell model. • Li{sup +} ion conducting Li{sub 2}MPO{sub 4}F has a 3D Li{sup +} ion diffusion network. • It is predicted that Li/Co or Li/Ni antisite defects are well-formed at a substantial concentration level.

  15. Dominant negative mutants of mammalian translation initiation factor eIF-4A define a critical role for eIF-4F in cap-dependent and cap-independent initiation of translation.

    PubMed Central

    Pause, A; Mthot, N; Svitkin, Y; Merrick, W C; Sonenberg, N

    1994-01-01

    Eukaryotic translation initiation factor-4A (eIF-4A) plays a critical role in binding of eukaryotic mRNAs to ribosomes. It has been biochemically characterized as an RNA-dependent ATPase and RNA helicase and is a prototype for a growing family of putative RNA helicases termed the DEAD box family. It is required for mRNA-ribosome binding both in its free form and as a subunit of the cap binding protein complex, eIF-4F. To gain further understanding into the mechanism of action of eIF-4A in mRNA-ribosome binding, defective eIF-4A mutants were tested for their abilities to function in a dominant negative manner in a rabbit reticulocyte translation system. Several mutants were demonstrated to be potent inhibitors of translation. Addition of mutant eIF-4A to a rabbit reticulocyte translation system strongly inhibited translation of all mRNAs studied including those translated by a cap-independent internal initiation mechanism. Addition of eIF-4A or eIF-4F relieved inhibition of translation, but eIF-4F was six times more effective than eIF-4A, whereas eIF-4B or other translation factors failed to relieve the inhibition. Kinetic experiments demonstrated that mutant eIF-4A is defective in recycling through eIF-4F, thus explaining the dramatic inhibition of translation. Mutant eIF-4A proteins also inhibited eIF-4F-dependent, but not eIF-4A-dependent RNA helicase activity. Taken together these results suggest that eIF-4A functions primarily as a subunit of eIF-4F, and that singular eIF-4A is required to recycle through the complex during translation. Surprisingly, eIF-4F, which binds to the cap structure, appears to be also required for the translation of naturally uncapped mRNAs. Images PMID:8131750

  16. High-Resolution Acoustic Imaging in the Agadir-Canyon Region, NW-Africa: Morphology, Processes and Geohazards

    NASA Astrophysics Data System (ADS)

    Krastel, S.; Wynn, R. B.; Feldens, P.; Unverricht, D.; Huehnerbach, V.; Stevenson, C.; Glogowski, S.; Schuerer, A.

    2014-12-01

    Agadir Canyon is one of the largest submarine canyons in the World, supplying giant submarine sediment gravity flows to the Agadir Basin and the wider Moroccan Turbidite System. While the Moroccan Turbidite System is extremely well investigated, almost no data from the source region, i.e. the Agadir Canyon, are available. Understanding why some submarine landslides remain as coherent blocks of sediment throughout their passage downslope, while others mix and disintegrate almost immediately after initial failure, is a major scientific challenge, which was addressed in the Agadir Canyon source region during Cruise MSM32. We collected ~ 1500 km of high-resolution seismic 2D-lines in combination with a dense net of hydroacoustic data. About 1000 km2 of sea floor were imaged during three deployments of TOBI (deep-towed sidescan sonar operated by the National Oceanography Centre Southampton). A total of 186 m of gravity cores and several giant box cores were recovered at more than 50 stations. The new data show that Agadir canyon is the source area of the world's largest submarine sediment flow, which occurred about 60,000 years ago. Up to 160 km3 of sediment was transported to the deep ocean in a single catastrophic event. For the first time, sediment flows of this scale have been tracked along their entire flow pathway. A major landslide area was identified south of Agadir Canyon. Landslide material enters Agadir canyon in about 2500 m water depth; the material is transported as debrite for at least another 200 km down the canyon. Initial data suggest that the last major slide from this source entered Agadir canyon at least 130,000 years ago. A large field of living deep-water corals was imaged north of Agadir canyon. To our knowledge, these are the first living cold water corals recovered off the coast of Morocco (except for the Gulf of Cadiz). They represent an important link between the known cold-water coral provinces off Mauritania and in the Gulf of Cdiz.

  17. Attacking a Nexus of the Oncogenic Circuitry by Reversing Aberrant eIF4F-Mediated Translation

    PubMed Central

    Bitterman, Peter B.; Polunovsky, Vitaly A.

    2012-01-01

    Notwithstanding their genetic complexity, different cancers share a core group of perturbed pathways converging upon a few regulatory nodes that link the intracellular signaling network with the basic metabolic machinery. The clear implication of this view for cancer therapy is that instead of targeting individual genetic alterations one-by-one, the next generation of cancer therapeutics will target critical hubs in the cancer network. One such hub is the translation initiation complex eIF4F, which integrates several cancer-related pathways into a self-amplifying signaling system. When hyperactivated by apical oncogenic signals, the eIF4F-driven translational apparatus selectively switches the translational repertoire of a cell towards malignancy. This central integrative role of pathologically activated eIF4F has motivated the development of small molecule inhibitors to correct its function. A genome-wide, systems-level means to objectively evaluate the pharmacological response to therapeutics targeting eIF4F remains an unmet challenge. PMID:22572598

  18. Carbothermal reduction synthesis of carbon coated Na2FePO4F for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Cui, Dongming; Chen, Shasha; Han, Chang; Ai, Changchun; Yuan, Liangjie

    2016-01-01

    Carbon coated spherical Na2FePO4F particles with typical diameters from 500 nm to 1 μm have been synthesized through an economical carbothermal reduction method with a simple apparatus. Mixed carbon source consists of citric acid and phenolic resin can form highly graphitized carbon and remarkably improve the electrical conductivity. When cycled against lithium, Na2FePO4F/C cathodes deliver maximum discharge capacity of 119 mAh g-1 at a low rate of 0.05 C. Reversible capacity of 110 mAh g-1, 74 mAh g-1 and 52 mAh g-1 can be obtained at 0.1 C, 1 C and 2 C rates, respectively. And after 30 cycles at 0.1 C, 91% of the discharge capacity can still be maintained. The electrochemical kinetic characteristic of electrode material is investigated by EIS and the apparent Li+ diffusion coefficient in the Li/Na2FePO4F system is evaluated to be as high as 1.152 × 10-11 cm2 s-1. This study demonstrates that the practical and economical synthesis process can be a promising way for industrial production of high performance Na2FePO4F/C electrode material for large-scale lithium ion batteries.

  19. A novel frameshift mutation of POU4F3 gene associated with autosomal dominant non-syndromic hearing loss

    SciTech Connect

    Lee, Hee Keun; Park, Hong-Joon; Lee, Kyu-Yup; Park, Rekil; Kim, Un-Kyung

    2010-06-04

    Autosomal dominant mutations in the transcription factor POU4F3 gene are associated with non-syndromic hearing loss in humans; however, there have been few reports of mutations in this gene worldwide. We performed a mutation analysis of the POU4F3 gene in 42 unrelated Koreans with autosomal dominant non-syndromic hearing loss, identifying a novel 14-bp deletion mutation in exon 2 (c.662del14) in one patient. Audiometric examination revealed severe bilateral sensorineural hearing loss in this patient. The novel mutation led to a truncated protein that lacked both functional POU domains. We further investigated the functional distinction between wild-type and mutant POU4F3 proteins using in vitro assays. The wild-type protein was completely localized in the nucleus, while the truncation of protein seriously affected its nuclear localization. In addition, the mutant failed to activate reporter gene expression. This is the first report of a POU4F3 mutation in Asia, and moreover our data suggest that further investigation will need to delineate ethnicity-specific genetic background for autosomal dominant non-syndromic hearing loss within Asian populations.

  20. 4f fine-structure levels as the dominant error in the electronic structures of binary lanthanide oxides.

    PubMed

    Huang, Bolong

    2016-04-01

    The ground-state 4f fine-structure levels in the intrinsic optical transition gaps between the 2p and 5d orbitals of lanthanide sesquioxides (Ln2 O3 , Ln = La…Lu) were calculated by a two-way crossover search for the U parameters for DFT + U calculations. The original 4f-shell potential perturbation in the linear response method were reformulated within the constraint volume of the given solids. The band structures were also calculated. This method yields nearly constant optical transition gaps between Ln-5d and O-2p orbitals, with magnitudes of 5.3 to 5.5 eV. This result verifies that the error in the band structure calculations for Ln2 O3 is dominated by the inaccuracies in the predicted 4f levels in the 2p-5d transition gaps, which strongly and non-linearly depend on the on-site Hubbard U. The relationship between the 4f occupancies and Hubbard U is non-monotonic and is entirely different from that for materials with 3d or 4d orbitals, such as transition metal oxides. This new linear response DFT + U method can provide a simpler understanding of the electronic structure of Ln2 O3 and enables a quick examination of the electronic structures of lanthanide solids before hybrid functional or GW calculations. © 2015 Wiley Periodicals, Inc. PMID:26666512

  1. Acoustic Tooth Cleaner

    NASA Technical Reports Server (NTRS)

    Heyman, J. S.

    1984-01-01

    Acoustically-energized water jet aids in plaque breakdown. Acoustic Wand includes acoustic transducer 1/4 wave plate, and tapered cone. Together elements energize solution of water containing mild abrasive injected into mouth to help prevent calculous buildup.

  2. Time-series observations of hydrothermal discharge using an acoustic imaging sonar: a NEPTUNE observatory case study

    NASA Astrophysics Data System (ADS)

    Xu, Guangyu; Bemis, Karen; Jackson, Darrell; Light, Russ

    2015-04-01

    One intriguing feature of a mid-ocean ridge hydrothermal system is the intimate interconnections among hydrothermal, geological, oceanic, and biological processes. The advent of the NEPTUNE observatory operated by Ocean Networks Canada at the Endeavour Segment, Juan de Fuca Ridge enables scientists to study these interconnections through multidisciplinary, continuous, real-time observations. In this study, we present the time-series observations of a seafloor hydrothermal vent made using the Cabled Observatory Vent Imaging Sonar (COVIS). COVIS is currently connected to the NEPTUNE observatory to monitor the hydrothermal discharge from the Grotto mound on the Endeavour Segment. Since its deployment in 2010, COVIS has recorded a 3-year long dataset of the shape and outflow fluxes of the buoyant plumes above Grotto along with the areal coverage of its diffuse flow discharge. The interpretation of these data in light of contemporaneous observations of ocean currents, venting temperature, and seismicity made using other NEPTUNE observatory instruments reveals significant impacts of ocean currents and geological events on hydrothermal venting. In this study, we summarize these findings in the hope of forming a more complete understanding of the intricate interconnections among oceanic, geological, and hydrothermal processes.

  3. A high performance hybrid capacitor with Li2CoPO4F cathode and activated carbon anode

    NASA Astrophysics Data System (ADS)

    Karthikeyan, K.; Amaresh, S.; Kim, K. J.; Kim, S. H.; Chung, K. Y.; Cho, B. W.; Lee, Y. S.

    2013-06-01

    For the first time, we report the possibility of utilizing Li2CoPO4F as a novel cathode material for hybrid capacitor applications. Li2CoPO4F powders were prepared by a conventional two-step solid state method. A hybrid cell was fabricated using Li2CoPO4F as the cathode along with activated carbon (AC) as the anode in 1 M LiPF6 dissolved in 1 : 1 EC/DMC electrolyte and its electrochemical properties were examined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and constant current charge-discharge (C-D) techniques. The Li2CoPO4F/AC cell is capable of delivering a discharge capacitance of 42 F g-1 at 150 mA g-1 current density within 0-3 V region having excellent coulombic efficiency of over 99% even after 1000 cycles. Furthermore, the Li2CoPO4F/AC cell exhibited excellent rate performance with an energy density of ~24 W h kg-1 at 1100 mA g-1 current and maintained about 92% of its initial value even after 30 000 C-D cycles. Electrochemical impedance spectroscopy was conducted to corroborate the results that were obtained and described.For the first time, we report the possibility of utilizing Li2CoPO4F as a novel cathode material for hybrid capacitor applications. Li2CoPO4F powders were prepared by a conventional two-step solid state method. A hybrid cell was fabricated using Li2CoPO4F as the cathode along with activated carbon (AC) as the anode in 1 M LiPF6 dissolved in 1 : 1 EC/DMC electrolyte and its electrochemical properties were examined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and constant current charge-discharge (C-D) techniques. The Li2CoPO4F/AC cell is capable of delivering a discharge capacitance of 42 F g-1 at 150 mA g-1 current density within 0-3 V region having excellent coulombic efficiency of over 99% even after 1000 cycles. Furthermore, the Li2CoPO4F/AC cell exhibited excellent rate performance with an energy density of ~24 W h kg-1 at 1100 mA g-1 current and maintained about 92% of its initial value even after 30 000 C-D cycles. Electrochemical impedance spectroscopy was conducted to corroborate the results that were obtained and described. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00760j

  4. Silicon etch using SF{sub 6}/C{sub 4}F{sub 8}/Ar gas mixtures

    SciTech Connect

    Bates, Robert L.; Stephan Thamban, P. L.; Goeckner, Matthew J.; Overzet, Lawrence J.

    2014-07-01

    While plasmas using mixtures of SF{sub 6}, C{sub 4}F{sub 8}, and Ar are widely used in deep silicon etching, very few studies have linked the discharge parameters to etching results. The authors form such linkages in this report. The authors measured the optical emission intensities of lines from Ar, F, S, SF{sub x}, CF{sub 2}, C{sub 2}, C{sub 3}, and CS as a function of the percentage C{sub 4}F{sub 8} in the gas flow, the total gas flow rate, and the bias power. In addition, the ion current density and electron temperature were measured using a floating Langmuir probe. For comparison, trenches were etched of various widths and the trench profiles (etch depth, undercut) were measured. The addition of C{sub 4}F{sub 8} to an SF{sub 6}/Ar plasma acts to reduce the availability of F as well as increase the deposition of passivation film. Sulfur combines with carbon in the plasma efficiently to create a large optical emission of CS and suppress optical emissions from C{sub 2} and C{sub 3}. At low fractional flows of C{sub 4}F{sub 8}, the etch process appears to be controlled by the ion flux more so than by the F density. At large C{sub 4}F{sub 8} fractional flows, the etch process appears to be controlled more by the F density than by the ion flux or deposition rate of passivation film. CF{sub 2} and C{sub 2} do not appear to cause deposition from the plasma, but CS and other carbon containing molecules as well as ions do.

  5. SBI-0640756 Attenuates the Growth of Clinically Unresponsive Melanomas by Disrupting the eIF4F Translation Initiation Complex.

    PubMed

    Feng, Yongmei; Pinkerton, Anthony B; Hulea, Laura; Zhang, Tongwu; Davies, Michael A; Grotegut, Stefan; Cheli, Yann; Yin, Hongwei; Lau, Eric; Kim, Hyungsoo; De, Surya K; Barile, Elisa; Pellecchia, Maurizio; Bosenberg, Marcus; Li, Jian-Liang; James, Brian; Hassig, Christian A; Brown, Kevin M; Topisirovic, Ivan; Ronai, Ze'ev A

    2015-12-15

    Disrupting the eukaryotic translation initiation factor 4F (eIF4F) complex offers an appealing strategy to potentiate the effectiveness of existing cancer therapies and to overcome resistance to drugs such as BRAF inhibitors (BRAFi). Here, we identified and characterized the small molecule SBI-0640756 (SBI-756), a first-in-class inhibitor that targets eIF4G1 and disrupts the eIF4F complex. SBI-756 impaired the eIF4F complex assembly independently of mTOR and attenuated growth of BRAF-resistant and BRAF-independent melanomas. SBI-756 also suppressed AKT and NF-?B signaling, but small-molecule derivatives were identified that only marginally affected these pathways while still inhibiting eIF4F complex formation and melanoma growth, illustrating the potential for further structural and functional manipulation of SBI-756 as a drug lead. In the gene expression signature patterns elicited by SBI-756, DNA damage, and cell-cycle regulatory factors were prominent, with mutations in melanoma cells affecting these pathways conferring drug resistance. SBI-756 inhibited the growth of NRAS, BRAF, and NF1-mutant melanomas in vitro and delayed the onset and reduced the incidence of Nras/Ink4a melanomas in vivo. Furthermore, combining SBI-756 and a BRAFi attenuated the formation of BRAFi-resistant human tumors. Taken together, our findings show how SBI-756 abrogates the growth of BRAF-independent and BRAFi-resistant melanomas, offering a preclinical rationale to evaluate its antitumor effects in other cancers. Cancer Res; 75(24); 5211-8. 2015 AACR. PMID:26603897

  6. The crystal structure of bgvadite (Na2SrBa2Al4F20)

    NASA Astrophysics Data System (ADS)

    Bali?-uni?, Ton?i

    2014-08-01

    The crystal structure of bgvadite, Na2SrBa2Al4F20, has been solved and refined to a R1 factor of 4.4 % from single-crystal data (Mo K? X-ray diffraction, CCD area detector) on a sample from the cryolite deposit at Ivittuut, SW Greenland. Bgvadite is monoclinic, P21/ n space group, with unit cell parameters a = 7.134(1), b = 19.996(3) and c = 5.3440(8) , ? = 90.02(1)o. A close proximity of the crystal structure to an orthorhombic symmetry and the presence of the two twin components in a nearly 1:1 ratio suggest that the investigated bgvadite crystal has originally formed as a high-temperature orthorhombic polymorph which on cooling transformed to the stable low temperature monoclinic structure. The bgvadite crystal structure has groupings of cation-fluoride coordination polyhedra similar to those found in the crystal structures of the genetically closely associated minerals jarlite and jrgensenite. However, its structure type is different from the latter two. The fluoridoaluminate framework of bgvadite consists of infinite zig-zag chains of cis-connected AlF6 coordination octahedra. The 1 ?[AlF5] chains are interconnected by infinite chains of Na-F coordination polyhedra which extend in the same direction. Na is coordinated by nine F atoms if its full surrounding is taken in consideration, but makes significant chemical bonds only to closest five. The chains of AlF6 and NaF9 coordination polyhedra form double layers. In the centre of layers, relatively large voids in the form of pentagonal antiprisms are occupied by Sr atoms which make chemical bonds with the closest six F atoms. Between the SrF10 coordinations in the centre of layers run empty channels. The double layers are interconnected by Ba atoms which are coordinated by eight F atoms and fill the spaces between the layers. Bgvadite belongs to the group of fluoridoaluminates with infinite chains of cis-connected AlF6 coordination octahedra, alike those found in the crystal structures of Ba-fluoridoaluminates.

  7. Isolating the auditory system from acoustic noise during functional magnetic resonance imaging: Examination of noise conduction through the ear canal, head, and bodya)

    PubMed Central

    Ravicz, Michael E.; Melcher, Jennifer R.

    2007-01-01

    Approaches were examined for reducing acoustic noise levels heard by subjects during functional magnetic resonance imaging (fMRI), a technique for localizing brain activation in humans. Specifically, it was examined whether a device for isolating the head and ear canal from sound (a “helmet”) could add to the isolation provided by conventional hearing protection devices (i.e., earmuffs and earplugs). Both subjective attenuation (the difference in hearing threshold with versus without isolation devices in place) and objective attenuation (difference in ear-canal sound pressure) were measured. In the frequency range of the most intense fMRI noise (1–1.4 kHz), a helmet, earmuffs, and earplugs used together attenuated perceived sound by 55–63 dB, whereas the attenuation provided by the conventional devices alone was substantially less: 30–37 dB for earmuffs, 25–28 dB for earplugs, and 39–41 dB for earmuffs and earplugs used together. The data enabled the clarification of the relative importance of ear canal, head, and body conduction routes to the cochlea under different conditions: At low frequencies (≤500 Hz), the ear canal was the dominant route of sound conduction to the cochlea for all of the device combinations considered. At higher frequencies (>500 Hz), the ear canal was the dominant route when either earmuffs or earplugs were worn. However, the dominant route of sound conduction was through the head when both earmuffs and earplugs were worn, through both ear canal and body when a helmet and earmuffs were worn, and through the body when a helmet, earmuffs, and earplugs were worn. It is estimated that a helmet, earmuffs, and earplugs together will reduce the most intense fMRI noise levels experienced by a subject to 60–65 dB SPL. Even greater reductions in noise should be achievable by isolating the body from the surrounding noise field. PMID:11206150

  8. Imaging Transverse Isotropic Properties of Muscle by Monitoring Acoustic Radiation Force Induced Shear Waves using a 2D Matrix Ultrasound Array

    PubMed Central

    Wang, Michael; Byram, Brett; Palmeri, Mark; Rouze, Ned; Nightingale, Kathryn

    2013-01-01

    A 2D matrix ultrasound array is used to monitor acoustic radiation force impulse (ARFI) induced shear wave propagation in 3D in excised canine muscle. From a single acquisition, both the shear wave phase and group velocity can be calculated to estimate the shear wave speed (SWS) along and across the fibers, as well as the fiber orientation in 3D. The true fiber orientation found using the 3D Radon Transform on B-mode volumes of the muscle was used to verify the fiber direction estimated from shear wave data. For the simplified imaging case when the ARFI push can be oriented perpendicular to the fibers, the error in estimating the fiber orientation using phase and group velocity measurements was 3.5 2.6 and 3.4 1.4 (mean standard deviation), respectively, over six acquisitions in different muscle samples. For the more general case when the push is oblique to the fibers, the angle between the push and the fibers is found using the dominant orientation of the shear wave displacement magnitude. In 30 acquisitions on six different muscle samples with oblique push angles up to 40, the error in the estimated fiber orientation using phase and group velocity measurements was 5.42.9 and 5.33.2, respectively, after estimating and accounting for the additional unknown push angle. Either the phase or group velocity measurements can be used to estimate fiber orientation and SWS along and across the fibers. Although it is possible to perform these measurements when the push is not perpendicular to the fibers, highly oblique push angles induce lower shear wave amplitudes which can cause inaccurate SWS measurements. PMID:23686942

  9. Normal values of liver shear wave velocity in healthy children assessed by acoustic radiation force impulse imaging using a convex probe and a linear probe.

    PubMed

    Fontanilla, Teresa; Cañas, Teresa; Macia, Araceli; Alfageme, Marta; Gutierrez Junquera, Carolina; Malalana, Ana; Luz Cilleruelo, Maria; Roman, Enriqueta; Miralles, Maria

    2014-03-01

    Acoustic radiation force impulse (ARFI) is an image-guided ultrasound elastography method that allows quantification of liver stiffness by measurement of shear wave velocity. One purpose of the work described in this article was to determine the normal liver stiffness values of healthy children using ARFI with two different probes, 4 C1 and 9 L4. Another purpose was to evaluate the effects of site of measurement, age, gender and body mass index on liver stiffness values. This prospective study included 60 healthy children (newborn to 14 y) divided into four age groups. One thousand two hundred ARFI measurements were performed, that is, 20 measurements per patient (5 measurements in each lobe, with each probe). Means, standard deviations (SD) and confidence intervals for velocity were calculated for each hepatic lobe and each probe in each age group and for the whole group. Mean shear wave velocity measured in the right lobe was 1.19 ± 0.04 m/s (SD = 0.13) with the 4 C1 transducer and 1.15 ± 0.04 m/s (SD = 0.15) with the 9 L4 transducer. Age had a small effect on shear wave measurements. Body mass index and sex had no significant effects on ARFI values, whereas site of measurement had a significant effect, with lower ARFI values in the right hepatic lobe. ARFI is a non-invasive technique that is feasible to perform in children with both the 4 C1 and 9 L4 probes. The aforementioned velocity values obtained in the right lobe may be used as reference values for normal liver stiffness in children. PMID:24361222

  10. Observation of cavitation bubbles and acoustic streaming in high intensity ultrasound fields

    NASA Astrophysics Data System (ADS)

    Uemura, Yuuki; Sasaki, Kazuma; Minami, Kyohei; Sato, Toshio; Choi, Pak-Kon; Takeuchi, Shinichi

    2015-07-01

    We observed the behavior of acoustic cavitation by sonochemical luminescence and ultrasound B-mode imaging with ultrasound diagnostic equipment in a standing-wave ultrasound field and focused ultrasound field. Furthermore, in order to investigate the influence of acoustic streaming on acoustic cavitation bubbles, we performed flow analysis of the sound field using particle image velocimetry. We found that acoustic cavitation bubbles are stirred by circulating acoustic streaming and local vortexes occurring in the water tank of the standing-wave ultrasound exposure system. We considered that the acoustic cavitation bubbles are carried away by acoustic streaming due to the high ultrasound pressure in the focused ultrasound field.

  11. Acoustic transducer

    DOEpatents

    Drumheller, Douglas S. (Cedar Crest, NM)

    1997-01-01

    An acoustic transducer comprising a one-piece hollow mandrel into the outer surface of which is formed a recess with sides perpendicular to the central axis of the mandrel and separated by a first distance and with a bottom parallel to the central axis and within which recess are a plurality of washer-shaped discs of a piezoelectric material and at least one disc of a temperature-compensating material with the discs being captured between the sides of the recess in a pre-stressed interference fit, typically at 2000 psi of compressive stress. The transducer also includes a power supply and means to connect to a measurement device. The transducer is intended to be used for telemetry between a measurement device located downhole in an oil or gas well and the surface. The transducer is of an construction that is stronger with fewer joints that could leak fluids into the recess holding the piezoelectric elements than is found in previous acoustic transducers.

  12. Acoustic transducer

    DOEpatents

    Drumheller, D.S.

    1997-12-30

    An acoustic transducer is described comprising a one-piece hollow mandrel into the outer surface of which is formed a recess with sides perpendicular to the central axis of the mandrel and separated by a first distance and with a bottom parallel to the central axis and within which recess are a plurality of washer-shaped discs of a piezoelectric material and at least one disc of a temperature-compensating material with the discs being captured between the sides of the recess in a pre-stressed interference fit, typically at 2,000 psi of compressive stress. The transducer also includes a power supply and means to connect to a measurement device. The transducer is intended to be used for telemetry between a measurement device located downhole in an oil or gas well and the surface. The transducer is of an construction that is stronger with fewer joints that could leak fluids into the recess holding the piezoelectric elements than is found in previous acoustic transducers. 4 figs.

  13. Air-coupled acoustic thermography for in-situ evaluation

    NASA Technical Reports Server (NTRS)

    Zalameda, Joseph N. (Inventor); Winfree, William P. (Inventor); Yost, William T. (Inventor)

    2010-01-01

    Acoustic thermography uses a housing configured for thermal, acoustic and infrared radiation shielding. For in-situ applications, the housing has an open side adapted to be sealingly coupled to a surface region of a structure such that an enclosed chamber filled with air is defined. One or more acoustic sources are positioned to direct acoustic waves through the air in the enclosed chamber and towards the surface region. To activate and control each acoustic source, a pulsed signal is applied thereto. An infrared imager focused on the surface region detects a thermal image of the surface region. A data capture device records the thermal image in synchronicity with each pulse of the pulsed signal such that a time series of thermal images is generated. For enhanced sensitivity and/or repeatability, sound and/or vibrations at the surface region can be used in feedback control of the pulsed signal applied to the acoustic sources.

  14. The Revised Human Liver Cytochrome P450 “Pie”: Absolute Protein Quantification of CYP4F and CYP3A Enzymes Using Targeted Quantitative Proteomics

    PubMed Central

    Michaels, Scott

    2014-01-01

    The CYP4F subfamily of enzymes has been identified recently to be involved in the metabolism of endogenous compounds (arachidonic acid and leukotriene B4), nutrients (vitamins K1 and E), and xenobiotics (pafuramidine and fingolimod). CYP4F2 and CYP4F3B are reported to be expressed in the human liver. However, absolute concentrations of these enzymes in human liver microsomes (HLMs) and their interindividual variability have yet to be determined because of the lack of specific antibodies. Here, an liquid chromatography with tandem mass spectrometry (LC-MS/MS)-based targeted quantitative proteomic approach was employed to determine the absolute protein concentrations of CYP4F2 and CYP4F3B compared with CYP3A in two panels of HLMs (n = 31). As a result, the human hepatic cytochrome P450 (P450) “pie” has been revised to include the contribution of CYP4F enzymes, which amounts to 15% of the total hepatic cytochrome P450 enzymes. CYP4F3B displayed low interindividual variability (3.3-fold) in the HLM panels whereas CYP4F2 displayed large variability (21-fold). However, CYP4F2 variability decreased to 3.4-fold if the two donors with the lowest expression were excluded. In contrast, CYP3A exhibited 29-fold interindividual variability in the same HLM panels. The proposed marker reaction for CYP4F enzymes pafuramidine/DB289 M1 formation did not correlate with CYP4F protein content, suggesting alternate metabolic pathways for DB289 M1 formation in HLMs. In conclusion, CYP4F enzymes are highly expressed in the human liver and their physiologic and pharmacologic roles warrant further investigation. PMID:24816681

  15. Magneto-structural variety of new 3d-4f-4(5)d heterotrimetallic complexes.

    PubMed

    Visinescu, Diana; Alexandru, Maria-Gabriela; Madalan, Augustin M; Pichon, Cline; Duhayon, Carine; Sutter, Jean-Pascal; Andruh, Marius

    2015-10-14

    Three families of heterotrimetallic chains (type 1-type 3), with different topologies, have been obtained by reacting the 3d-4f complexes, [{Cu(L(1))}xLn(NO3)3] with x = 1 or 2, formed in situ by the reaction of Schiff-base bi-compartmental [Cu(II)(L(1))] complexes and lanthanide(iii) salts, with (NHBu3)3[M(CN)8] (M = Mo(V), W(V)). For type 1 series of compounds, 1-D coordination polymers, with the general formula [{Cu2(valpn)2Ln}{M(CN)8}]nH2OmCH3CN (where H2valpn = 1,3-propanediylbis(2-iminomethylene-6-methoxy-phenol), result from the association of trinuclear {CuLn(III)} moieties and [M(V)(CN)8](3-) anions acting as tri-connecting spacers [Ln = La (1), Ce (2), Eu (3), Tb (4), Ho (5), M = Mo; Ln = Tb (6), Ho (7), M = W; m = 0, n = 1.5 (7) and 2 (1-4, 6); n = 1, m = 1 (5)]. The type 2 family has the general formula [{Cu(valdp)Ln(H2O)4}{M(CN)8}]2H2OCH3CN (where H2valdp = 1,2-propanediylbis(2-iminomethylene-6-methoxy-phenol)) and also consists of heterotrimetallic chains involving binuclear {Cu(II)Ln(III)} units linked to [M(CN)8](3-) anions coordinating through two cyano groups [Ln = Gd (8), Tb (9), Dy (10); M = Mo; Ln = La (11), Gd (12), Tb (13), Dy (14); M = W]. With large Ln(III) ions (La(III) and Pr(III)), the type 3 family of heterotrimetallic compounds are assembled: [{Cu2(valdp)2Ln(H2O)4}{Mo(CN)8}]nCH3OHmCH3CN, n, m = 0, Ln = La (15); n = m = 1, Pr (16), in which the trinuclear {CuLn(III)} nodes are connected to [Mo(V)(CN)8](3-) anions that act as tetra-connecting spacers. For Tb(III) derivatives of the type 1 (compounds 4 and 6), the DC magnetic properties indicate a predominant ferromagnetic Cu(II)-Tb(III) interaction, while the AC magnetic susceptibility (in the presence of a static magnetic field, HDC = 3000 Oe) emphasize the slow relaxation of the magnetization (Ueff/kB = 20.55 K and ?0 = 5.5 10(-7) s for compound 4, Ueff/kBT = 15.1 K and ?0 = 1.5 10(-7) s for compound 6). A predominant ferromagnetic Cu(II)-Ln(III) interaction was also observed in the type 2 series (compounds 8-10 and 12-14) as a result of the magnetic coupling between copper(ii) and lanthanide(iii) ions via the phenoxo-bridge. The magnetic behavior for the La(III) derivatives reveals that weak ferromagnetic interactions are also operative between the Cu(II) and the 4d/5d centers. PMID:26199073

  16. Studies on the complexation of Pr(III) and Nd(III) with glycyl-glycine (gly-gly) using spectral analysis of 4f-4f transitions and potentiometric titrations

    NASA Astrophysics Data System (ADS)

    Ranjana Devi, N.; Huidrom, Bimola; Rajmuhon Singh, N.

    2012-10-01

    The interaction of gly-gly with Pr(III) and Nd(III) have been studied in different aquated organic solvents like CH3OH, CH3CN, dioxane and DMF by using 4f-4f transitions spectra. Various energy interaction parameters like Slater Condon (Fk), Racah (Ek), Lande (?4f), nephelauxetic effect (?), bonding (b1/2) and percent covalency (?) parameters have been calculated to explain the nature of complexation. The intensity parameters like oscillator strength (P) and Judd-Ofelt parameters (T?, ? = 2, 4, 6) also support the mode of binding of gly-gly to metal ions. The results show that Pr(III) and Nd(III) with gly-gly form complexes by ionic linkages with carboxylate anion with weak covalency. The protonation constants and metal-ligand stability constants have also been determined by potentiometric measurements in aqueous medium at different temperatures (290, 300 and 310 K) at constant ionic strength, 0.1 mol dm-1. The results show the formation of metal-ligand complexes in the stoichiometric ratio 1:1. The stability of complexes is more in Nd(III) complexes as compared to Pr(III) complexes. Thermodynamic parameters (?G, ?H and ?S) of complexes were also calculated and the negative values of ?G and ?H show that the complex reactions are spontaneous and exothermic. The positive values of ?S indicate high stability of complex reactions which are enthalpy-driven.

  17. Acoustic cryocooler

    SciTech Connect

    Swift, G.W.; Martin, R.A.; Radebaugh, R.

    1990-09-04

    This patent describes an acoustic cryocooler with no moving parts is formed from a thermoacoustic driver (TAD) driving a pulse tube refrigerator (PTR) through a standing wave tube. Thermoacoustic elements in the TAD are spaced apart a distance effect to accommodate the increased thermal penetration length arising from the relatively low TAD operating frequency in the range of 15--60 Hz. At these low operating frequencies, a long tube is required to support the standing wave. The tube may be coiled to reduce the overall length of the cryocooler. One or two PTR's are located on the standing wave tube adjacent antinodes in the standing wave to be driven by the standing wave pressure oscillations. It is predicted that a heat input of 1000 W at 1000 K will maintain a cooling load of 5 W at 80 K.

  18. Acoustic cryocooler

    SciTech Connect

    Swift, G.W.; Martin, R.A.; Radebaugh, R.

    1989-09-26

    An acoustic cryocooler with no moving parts is formed from a thermoacoustic driver (TAD) driving a pulse tube refrigerator (PTR) through a standing wave tube. Thermoacoustic elements in the TAD are spaced apart a distance effective to accommodate the increased thermal penetration length arising from the relatively low TAD operating frequency in the range of 15-60 Hz. At these low operating frequencies, a long tube is required to support the standing wave. The tube may be coiled to reduce the overall length of the cryocooler. One or two PTR's are located on the standing wave tube adjacent antinodes in the standing wave to be driven by the standing wave pressure oscillations. It is predicted that a heat input of 1000 W at 1000 K will maintain a cooling load of 5 W at 80 K. 3 figs.

  19. Acoustic transducer

    DOEpatents

    Drumheller, Douglas S. (Cedar Crest, NM)

    2000-01-01

    An active acoustic transducer tool for use down-hole applications. The tool includes a single cylindrical mandrel including a shoulder defining the boundary of a narrowed portion over which is placed a sandwich-style piezoelectric tranducer assembly. The piezoelectric transducer assembly is prestressed by being placed in a thermal interference fit between the shoulder of the mandrel and the base of an anvil which is likewise positioned over the narrower portion of the mandrel. In the preferred embodiment, assembly of the tool is accomplished using a hydraulic jack to stretch the mandrel prior to emplacement of the cylindrical sandwich-style piezoelectric transducer assembly and anvil. After those elements are positioned and secured, the stretched mandrel is allowed to return substantially to its original (pre-stretch) dimensions with the result that the piezoelectric transducer elements are compressed between the anvil and the shoulder of the mandrel.

  20. Acoustic cryocooler

    DOEpatents

    Swift, Gregory W.; Martin, Richard A.; Radenbaugh, Ray

    1990-01-01

    An acoustic cryocooler with no moving parts is formed from a thermoacoustic driver (TAD) driving a pulse tube refrigerator (PTR) through a standing wave tube. Thermoacoustic elements in the TAD are spaced apart a distance effective to accommodate the increased thermal penetration length arising from the relatively low TAD operating frequency in the range of 15-60 Hz. At these low operating frequencies, a long tube is required to support the standing wave. The tube may be coiled to reduce the overall length of the cryocooler. One or two PTR's are located on the standing wave tube adjacent antinodes in the standing wave to be driven by the standing wave pressure oscillations. It is predicted that a heat input of 1000 W at 1000 K will maintian a cooling load of 5 W at 80 K.

  1. BDNF gene therapy induces auditory nerve survival and fiber sprouting in deaf Pou4f3 mutant mice.

    PubMed

    Fukui, H; Wong, H T; Beyer, L A; Case, B G; Swiderski, D L; Di Polo, A; Ryan, A F; Raphael, Y

    2012-01-01

    Current therapy for patients with hereditary absence of cochlear hair cells, who have severe or profound deafness, is restricted to cochlear implantation, a procedure that requires survival of the auditory nerve. Mouse mutations that serve as models for genetic deafness can be utilized for developing and enhancing therapies for hereditary deafness. A mouse with Pou4f3 loss of function has no hair cells and a subsequent, progressive degeneration of auditory neurons. Here we tested the influence of neurotrophin gene therapy on auditory nerve survival and peripheral sprouting in Pou4f3 mouse ears. BDNF gene transfer enhanced preservation of auditory neurons compared to control ears, in which nearly all neurons degenerated. Surviving neurons in treated ears exhibited pronounced sprouting of nerve fibers into the auditory epithelium, despite the absence of hair cells. This enhanced nerve survival and regenerative sprouting may improve the outcome of cochlear implant therapy in patients with hereditary deafness. PMID:23150788

  2. Acoustic telemetry.

    SciTech Connect

    Drumheller, Douglas Schaeffer; Kuszmaul, Scott S.

    2003-08-01

    Broadcasting messages through the earth is a daunting task. Indeed, broadcasting a normal telephone conversion through the earth by wireless means is impossible with todays technology. Most of us don't care, but some do. Industries that drill into the earth need wireless communication to broadcast navigation parameters. This allows them to steer their drill bits. They also need information about the natural formation that they are drilling. Measurements of parameters such as pressure, temperature, and gamma radiation levels can tell them if they have found a valuable resource such as a geothermal reservoir or a stratum bearing natural gas. Wireless communication methods are available to the drilling industry. Information is broadcast via either pressure waves in the drilling fluid or electromagnetic waves in the earth and well tubing. Data transmission can only travel one way at rates around a few baud. Given that normal Internet telephone modems operate near 20,000 baud, these data rates are truly very slow. Moreover, communication is often interrupted or permanently blocked by drilling conditions or natural formation properties. Here we describe a tool that communicates with stress waves traveling through the steel drill pipe and production tubing in the well. It's based on an old idea called Acoustic Telemetry. But what we present here is more than an idea. This tool exists, it's drilled several wells, and it works. Currently, it's the first and only acoustic telemetry tool that can withstand the drilling environment. It broadcasts one way over a limited range at much faster rates than existing methods, but we also know how build a system that can communicate both up and down wells of indefinite length.

  3. Nuclear magnetic resonance of Al-27 in topaz, Al2SiO4/F, OH/2.

    NASA Technical Reports Server (NTRS)

    Tsang, T.; Ghose, S.

    1972-01-01

    The Al-27 nuclear quadrupolar coupling constant and asymmetry parameter (eta) in topaz have been determined to be 1.67 (plus or minus 0.03) MHz and 0.38 plus or minus 0.05, respectively. These values and the orientations of the principal axes are consistent with the Fe(3+) paramagnetic resonance data and with the symmetry of the AlO4F2 octahedron.

  4. ApoA-I Mimetic Peptide 4F Rescues Pulmonary Hypertension by Inducing MicroRNA-193-3p

    PubMed Central

    Sharma, Salil; Umar, Soban; Potus, Francois; Iorga, Andrea; Wong, Gabriel; Meriwether, David; Breuils-Bonnet, Sandra; Mai, Denise; Navab, Kaveh; Ross, David; Navab, Mohamad; Provencher, Steeve; Fogelman, Alan M.; Bonnet, Sébastien; Reddy, Srinivasa T.; Eghbali, Mansoureh

    2014-01-01

    Background Pulmonary Arterial Hypertension (PAH) is a chronic lung disease associated with severe pulmonary vascular changes. A pathogenic role of oxidized lipids such as hydroxyeicosatetraenoic acids (HETEs) and hydroxyoctadecadienoic acids (HODEs) is well established in vascular disease. Apolipoprotein A-I (apoA-I) mimetic peptides including 4F have been reported to reduce levels of these oxidized lipids and improve vascular disease. However, the role of oxidized lipids in the progression of PAH and the therapeutic action of 4F in PAH is not well established. Methods and Results We studied two different rodent models of Pulmonary Hypertension (PH); a monocrotaline (MCT) rat model and a hypoxia mouse model. Plasma levels of HETEs and HODEs were significantly elevated in PH. 4F treatment reduced these levels and rescued pre-existing PH in both models. MicroRNA analysis revealed that miR193-3p (miR193) was significantly downregulated in the lung tissue and in serum from both PAH patients and in PH rodents. In-vivo miR193 overexpression in the lungs rescued pre-existing PH and resulted in downregulation of lipoxygenases and insulin-like growth factor-1 receptor. 4F restored PH-induced miR193 expression via transcription factor retinoid X receptor alpha (RXRα). Conclusions These studies establish the importance of microRNAs as downstream effectors of an apoA-I mimetic peptide in the rescue of PH and suggest that treatment with apoA-I mimetic peptides, or miR193 may have therapeutic value. PMID:24963038

  5. Effect of temperature on the electron attachment and detachment properties of c-C{sub 4}F{sub 6}

    SciTech Connect

    Datskos, P.G.; Christophorou, L.G. |; Carter, J.G.

    1994-06-01

    The temperature dependence of the low-energy electron attachment and autodetachment processes for c-C{sub 4}F{sub 6} in a N{sub 2} buffer gas has been studied in the temperature, T, range of 300 to 600 K and the mean electron energy, <{epsilon}>, range from 0.19 to 1.0 eV. The low-energy electron attachment rate constant for c-C{sub 4}F{sub 6} shows only a slight dependence on gas temperature. In contrast, the autodetachment frequency increases by more than four orders of magnitude when T is increased from 300 to 600 K. This increase in autodetachment is due to the increase in the internal energy content of the c-C{sub 4},F{sub 6}{sup {minus}} anion with increasing T. The autodetachment process under consideration is a heat-activated process and has an activation energy E* of 0.24 eV. Significance of these results to gaseous dielectrics is indicated.

  6. High-resolution electron spectroscopy of lanthanide (Ce, Pr, and Nd) complexes of cyclooctatetraene: The role of 4f electrons

    SciTech Connect

    Kumari, Sudesh; Roudjane, Mourad; Hewage, Dilrukshi; Yang Dongsheng; Liu Yang

    2013-04-28

    Cerium, praseodymium, and neodymium complexes of 1,3,5,7-cyclooctatetraene (COT) complexes were produced in a laser-vaporization metal cluster source and studied by pulsed-field ionization zero electron kinetic energy spectroscopy and quantum chemical calculations. The computations included the second-order Moller-Plesset perturbation theory, the coupled cluster method with single, double, and perturbative triple excitations, and the state-average complete active space self-consistent field method. The spectrum of each complex exhibits multiple band systems and is assigned to ionization of several low-energy electronic states of the neutral complex. This observation is different from previous studies of M(COT) (M = Sc, Y, La, and Gd), for which a single band system was observed. The presence of the multiple low-energy electronic states is caused by the splitting of the partially filled lanthanide 4f orbitals in the ligand field, and the number of the low-energy states increases rapidly with increasing number of the metal 4f electrons. On the other hand, the 4f electrons have a small effect on the geometries and vibrational frequencies of these lanthanide complexes.

  7. Acoustic optic hybrid (AOH) sensor

    PubMed

    Matthews; Arrieta

    2000-09-01

    The ability of laser vibrometers to receive and process acoustic echoes from the water surface above a submerged target is established and evaluated. Sonar echoes from a submerged target are collected from the water surface by a laser vibrometer. Feasibility of this approach to sensing underwater sound is demonstrated. If the acoustic excitation at an otherwise undisturbed water surface is 195 to 168 dB re: 1 microPa, signal-to-noise ratio (SNR), at the vibrometer output, is shown to range from about 46 to 6 dB. Capillary waves and gravity waves at the water surface are expected and shown to have some destructive effect on the process of echo retrieval. A series of experiments to quantify the surface wave effects is described. The wave experiment results are reported. A successful attempt to acquire echoes from a submerged target over a grid of points for further processing into a three-dimensional image is made and described. The data acquisition and beamforming techniques constitute a three-dimensional, acoustic optic, synthetic aperture sonar (SAS). Beamformed images are included. For an aircraft towing acoustic sensors through the water with a mechanical link, this technique holds the promise of increased safety and improved fuel efficiency. PMID:11008811

  8. Frequency steerable acoustic transducers

    NASA Astrophysics Data System (ADS)

    Senesi, Matteo

    Structural health monitoring (SHM) is an active research area devoted to the assessment of the structural integrity of critical components of aerospace, civil and mechanical systems. Guided wave methods have been proposed for SHM of plate-like structures using permanently attached piezoelectric transducers, which generate and sense waves to evaluate the presence of damage. Effective interrogation of structural health is often facilitated by sensors and actuators with the ability to perform electronic, i.e. phased array, scanning. The objective of this research is to design an innovative directional piezoelectric transducer to be employed for the localization of broadband acoustic events, or for the generation of Lamb waves for active interrogation of structural health. The proposed Frequency Steerable Acoustic Transducers (FSATs) are characterized by a spatial arrangement of active material which leads to directional characteristics varying with frequency. Thus FSATs can be employed both for directional sensing and generation of guided waves without relying on phasing and control of a large number of channels. The analytical expression of the shape of the FSATs is obtained through a theoretical formulation for continuously distributed active material as part of a shaped piezoelectric device. The FSAT configurations analyzed in this work are a quadrilateral array and a geometry which corresponds to a spiral in the wavenumber domain. The quadrilateral array is experimentally validated, confirming the concept of frequency-dependent directionality. Its limited directivity is improved by the Wavenumber Spiral FSAT (WS-FSAT), which, instead, is characterized by a continuous frequency dependent directionality. Preliminary validations of the WS-FSAT, using a laser doppler vibrometer, are followed by the implementation of the WS-FSAT as a properly shaped piezo transducer. The prototype is first used for localization of acoustic broadband sources. Signal processing algorithms and related imaging techniques for damage location are also presented. Finally, the WS-FSAT has also been experimentally validated in generation.

  9. Acoustic microscope using pressurized superfluid 4He

    NASA Astrophysics Data System (ADS)

    Karaki, Koichi; Suzuki, Masaru; Okuda, Yuichi

    1990-02-01

    An acoustic microscope has been developed which makes use of pressurized superfluid helium as an acoustic coupling medium. Acoustic micrographs were taken using pure superfluid 4He under saturated vapor pressure at 0.1 K and under 25 atm at 0.1 and 1.9 K, for the frequency of 380 MHz. By pressurizing liquid 4He, the acoustic attenuation decreases, the efficiency of the antireflection coating increases, and the power level of saturation caused by nonlinearity of the superfluid 4He is raised. A good signal-to-noise ratio of imaging is thus obtained. The entire imaging instrument set is within a closed cell. The focusing mechanism is composed of two voice coils of superconducting wire. Using a servocontrol mechanism with a sensor and drive coil, Z-direction stability was better than 0.05 ?m. The manipulation sensitivity is 0.5 ?m/mV, and the whole stroke is about 2 mm.

  10. Experimental demonstration of an acoustic magnifying hyperlens.

    PubMed

    Li, Jensen; Fok, Lee; Yin, Xiaobo; Bartal, Guy; Zhang, Xiang

    2009-12-01

    Acoustic metamaterials can manipulate sound waves in surprising ways, which include collimation, focusing, cloaking, sonic screening and extraordinary transmission. Recent theories suggested that imaging below the diffraction limit using passive elements can be realized by acoustic superlenses or magnifying hyperlenses. These could markedly enhance the capabilities in underwater sonar sensing, medical ultrasound imaging and non-destructive materials testing. However, these proposed approaches suffer narrow working frequency bands and significant resonance-induced loss, which hinders them from successful experimental realization. Here, we report the experimental demonstration of an acoustic hyperlens that magnifies subwavelength objects by gradually converting evanescent components into propagating waves. The fabricated acoustic hyperlens relies on straightforward cutoff-free propagation and achieves deep-subwavelength resolution with low loss over a broad frequency bandwidth. PMID:19855382

  11. Experimental demonstration of an acoustic magnifying hyperlens

    NASA Astrophysics Data System (ADS)

    Li, Jensen; Fok, Lee; Yin, Xiaobo; Bartal, Guy; Zhang, Xiang

    2009-12-01

    Acoustic metamaterials can manipulate sound waves in surprising ways, which include collimation, focusing, cloaking, sonic screening and extraordinary transmission. Recent theories suggested that imaging below the diffraction limit using passive elements can be realized by acoustic superlenses or magnifying hyperlenses. These could markedly enhance the capabilities in underwater sonar sensing, medical ultrasound imaging and non-destructive materials testing. However, these proposed approaches suffer narrow working frequency bands and significant resonance-induced loss, which hinders them from successful experimental realization. Here, we report the experimental demonstration of an acoustic hyperlens that magnifies subwavelength objects by gradually converting evanescent components into propagating waves. The fabricated acoustic hyperlens relies on straightforward cutoff-free propagation and achieves deep-subwavelength resolution with low loss over a broad frequency bandwidth.

  12. A family of three-dimensional 3d-4f and 4d-4f heterometallic coordination polymers based on mixed isonicotinate and 2-sulfobenzoate ligands: syntheses, structures and photoluminescent properties.

    PubMed

    Li, Xinfa; Huang, Yuanbiao; Cao, Rong

    2012-05-28

    Hydrothermal reactions of isonicotinic acid (Hina), 2-sulfobenzoic acid (H(2)sba), d-block metal salts and lanthanide oxides/hydroxides yielded 17 three-dimensional (3D) 3d-4f and 4d-4f heterometallic coordination polymers (HCPs). They are formulated as [LaAg(sba)(ina)(2)](n) (1), [Ln(2)Ag(2)(sba)(2)(ina)(4)(H(2)O)(2)](n) [Ln = Pr (2), Nd (3), Sm (4), Eu (5), Gd (6), Tb (7), Dy (8), Ho (9), Er (10)] and [Ln(2)Cu(2)(sba)(2)(ina)(4)(H(2)O)(2)](n) [Ln = La (11), Pr (12), Nd (13), Sm (14), Eu (15), Gd (16), Tb (17)]. Their structures were characterized by single crystal X-ray diffraction, powder X-ray diffraction (XRD), infrared (IR) spectroscopy, elemental analysis (EA), and thermogravimetric analysis (TGA). It reveals that they represent two structural types of 3D HCPs. Furthermore, the investigations of their solid-state photoluminescent (PL) property demonstrate the extraordinary emission behaviors. HCP 1(La-Ag) exhibits tunable blue-to-green PL emissions by variation of excitation light. HCPs 6(Gd-Ag), 11(La-Cu), 12(Pr-Cu) and 16(Gd-Cu) show d(10)-metal-based ligand-to-metal charge transfer (LMCT) or metal-to-ligand charge transfer (MLCT) emissions. HCPs 3(Nd-Ag), 4(Sm-Ag), 5(Eu-Ag), 7(Tb-Ag), 8(Dy-Ag), 13(Nd-Cu), 14(Sm-Cu), 15(Eu-Cu) and 17(Tb-Cu) display characteristic PL emissions of the corresponding Ln(III) ions, while both d(10)-metal-based and 4f-metal-centered emissions are observed in the emission spectra of 4(Sm-Ag), 8(Dy-Ag), 14(Sm-Cu) and 17(Tb-Cu). PMID:22476186

  13. Acoustic microscopy in the food industry

    NASA Astrophysics Data System (ADS)

    Watson, N.; Povey, M.; Corona, E.; Benedito, J.; Parker, N.

    2012-12-01

    Acoustic microscopy has been used for many years to image and measure the elastic properties of materials across a wide range of scientific disciplines. However the application of this technique in the food industry is scarce. In this paper we outline the operation of a reflection-mode acoustic microscope and discuss some of the issues relevant to its operation in the food sector. We then present two relevant case studies in which we employ acoustic microscopy to analyse potato cells and the fat structure in Iberian ham and chorizo.

  14. Opto-acoustic thrombolysis

    DOEpatents

    Celliers, Peter (Berkeley, CA); Da Silva, Luiz (Danville, CA); Glinsky, Michael (Livermore, CA); London, Richard (Orinda, CA); Maitland, Duncan (Livermore, CA); Matthews, Dennis (Moss Beach, CA); Fitch, Pat (Livermore, CA)

    2000-01-01

    This invention is a catheter-based device for generating an ultrasound excitation in biological tissue. Pulsed laser light is guided through an optical fiber to provide the energy for producing the acoustic vibrations. The optical energy is deposited in a water-based absorbing fluid, e.g. saline, thrombolytic agent, blood or thrombus, and generates an acoustic impulse in the fluid through thermoelastic and/or thermodynamic mechanisms. By pulsing the laser at a repetition rate (which may vary from 10 Hz to 100 kHz) an ultrasonic radiation field can be established locally in the medium. This method of producing ultrasonic vibrations can be used in vivo for the treatment of stroke-related conditions in humans, particularly for dissolving thrombus or treating vasospasm. The catheter can also incorporate thrombolytic drug treatments as an adjunct therapy and it can be operated in conjunction with ultrasonic detection equipment for imaging and feedback control and with optical sensors for characterization of thrombus type and consistency.

  15. The Sounds of Nanoscience: Acoustic STM Analogues

    ERIC Educational Resources Information Center

    Euler, Manfred

    2013-01-01

    A hands-on model of scanning tunnelling microscopy (STM) is presented. It uses near-field imaging with sound and computer assisted visualization to create acoustic mappings of resonator arrangements. Due to the (partial) analogy of matter and sound waves the images closely resemble STM scans of atoms. Moreover, the method can be extended to build…

  16. The Sounds of Nanoscience: Acoustic STM Analogues

    ERIC Educational Resources Information Center

    Euler, Manfred

    2013-01-01

    A hands-on model of scanning tunnelling microscopy (STM) is presented. It uses near-field imaging with sound and computer assisted visualization to create acoustic mappings of resonator arrangements. Due to the (partial) analogy of matter and sound waves the images closely resemble STM scans of atoms. Moreover, the method can be extended to build

  17. Automation and system integration of scanning tomographic acoustic microscope.

    PubMed

    Kent, S D; Lee, H

    1997-01-01

    The Scanning Tomographic Acoustic Microscope (STAM) is an instrument capable of performing subsurface imaging of microscopic specimens. Designed around the Scanning Laser Acoustic Microscope (SLAM), the STAM incorporates numerous hardware and software advances which allow automated imaging of the acoustic properties of thick specimens at high resolution. With these modifications the STAM is shown to be capable of image formation for tissue characterization and nondestructive evaluation (NDE) of microscopic specimens. This paper describes the design and operation of the STAM hardware, and software algorithms developed to permit high resolution imaging. Examples are provided to demonstrate the capability of multiple angle and multiple frequency tomographic reconstructions. PMID:9475432

  18. Order-disorder phase transition in the antiperovskite-type structure of synthetic kogarkoite, Na3SO4F

    NASA Astrophysics Data System (ADS)

    Avdontceva, Margarita S.; Zolotarev, Andrey A.; Krivovichev, Sergey V.

    2015-11-01

    High-temperature phase transition of synthetic kogarkoite, Na3SO4F, has been studied by high-temperature X-ray powder and single-crystal diffraction. The temperature of the phase transition can be estimated as 112.512.5 C. The low-temperature phase, ?-Na3SO4F, at 293 K, is monoclinic, P21/m, a=18.065(3), b=6.958(1), c=11.446(1) , ?=107.711(1), Z=12. The structure contains thirteen symmetrically independent Na sites with coordination numbers varying from 6 to 8, and six independent S sites. The high-temperature ?-phase at 423 K is rhombohedral, R-3m, a=6.94(1), c=24.58(4) , Z=9. The crystal structure of both polymorphs of Na3SO4F can be described as a 9R antiperovskite polytype based upon triplets of face-sharing [FNa6] octahedra linked into a three-dimensional framework by sharing corners. In the ?-modification, the SO4 tetrahedra are completely ordered and located in the framework cavities. In the ?-modification, there are only two symmetrically independent Na atoms in the structure. The main difference between the structures of the ?- and ?-phases is the degree of ordering of the SO4 tetrahedra: in the ?-modification, they are completely ordered, whereas, in the ?-modification, the complete disorder is observed, which is manifested in a number of low-occupied O sites around fully occupied S sites. The phase transition is therefore has an order-disorder character and is associated with the decrease of structural complexity measured as an information content per unit cell [577.528 bits for the low- (?) and 154.830 bits for the high- (?) temperature modifications].

  19. Differential phase acoustic microscope for micro-NDE

    NASA Technical Reports Server (NTRS)

    Waters, David D.; Pusateri, T. L.; Huang, S. R.

    1992-01-01

    A differential phase scanning acoustic microscope (DP-SAM) was developed, fabricated, and tested in this project. This includes the acoustic lens and transducers, driving and receiving electronics, scanning stage, scanning software, and display software. This DP-SAM can produce mechanically raster-scanned acoustic microscopic images of differential phase, differential amplitude, or amplitude of the time gated returned echoes of the samples. The differential phase and differential amplitude images provide better image contrast over the conventional amplitude images. A specially designed miniature dual beam lens was used to form two foci to obtain the differential phase and amplitude information of the echoes. High image resolution (1 micron) was achieved by applying high frequency (around 1 GHz) acoustic signals to the samples and placing two foci close to each other (1 micron). Tone burst was used in this system to obtain a good estimation of the phase differences between echoes from the two adjacent foci. The system can also be used to extract the V(z) acoustic signature. Since two acoustic beams and four receiving modes are available, there are 12 possible combinations to produce an image or a V(z) scan. This provides a unique feature of this system that none of the existing acoustic microscopic systems can provide for the micro-nondestructive evaluation applications. The entire system, including the lens, electronics, and scanning control software, has made a competitive industrial product for nondestructive material inspection and evaluation and has attracted interest from existing acoustic microscope manufacturers.

  20. What Is an Acoustic Neuroma

    MedlinePLUS

    ... ANAUSA.org Connect with us! What is an Acoustic Neuroma? Each heading slides to reveal information. Important ... Acoustic Neuroma Important Points To Know About an Acoustic Neuroma An acoustic neuroma, also called a vestibular ...

  1. Tailoring the coercivity in ferromagnetic ZnO thin films by 3d and 4f elements codoping

    NASA Astrophysics Data System (ADS)

    Lee, J. J.; Xing, G. Z.; Yi, J. B.; Chen, T.; Ionescu, M.; Li, S.

    2014-01-01

    Cluster free, Co (3d) and Eu (4f) doped ZnO thin films were prepared using ion implantation technique accompanied by post annealing treatments. Compared with the mono-doped ZnO thin films, the samples codoped with Co and Eu exhibit a stronger magnetization with a giant coercivity of 1200 Oe at ambient temperature. This was further verified through x-ray magnetic circular dichroism analysis, revealing the exchange interaction between the Co 3d electrons and the localized carriers induced by Eu3+ ions codoping. The insight gained with modulating coercivity in magnetic oxides opens up an avenue for applications requiring non-volatility in spintronic devices.

  2. Two 3d-4f nanomagnets formed via a two-step in situ reaction of picolinaldehyde.

    PubMed

    Liu, Jun-Liang; Chen, Yan-Cong; Li, Quan-Wen; Gmez-Coca, Silvia; Aravena, Daniel; Ruiz, Eliseo; Lin, Wei-Quan; Leng, Ji-Dong; Tong, Ming-Liang

    2013-07-25

    Two 3d-4f nanomagnets, [Dy(III)2Cu(II)7] (1) and [Gd(III)6Cu(II)12] (2), are synthesized under a two-step in situ reaction of picolinaldehyde. Not only the final adduct (hemiacetal), but also the intermediate (gem-diol) are "visualized" by X-ray single crystal diffraction. The Dy complex behaves as a single-molecule magnet, while the Gd complex exhibits a significant magnetocaloric effect. Theoretical calculations are employed to obtain the orientation of the magnetic moments and the magnetic exchange. PMID:23765169

  3. Single-ion 4f element magnetism: an ab-initio look at Ln(COT)2(-).

    PubMed

    Gendron, Frdric; Pritchard, Benjamin; Bolvin, Hlne; Autschbach, Jochen

    2015-12-14

    The electron densities associated with the Ln 4f shell, and spin and orbital magnetizations ('magnetic moment densities'), are investigated for the Ln(COT)2(-) series. The densities are obtained from ab-initio calculations including spin-orbit coupling. For Ln = Ce, Pr the magnetizations are also derived from crystal field models and shown to agree with the ab-initio results. Analysis of magnetizations from ab-initio calculations may be useful in assisting research on single molecule magnets. PMID:26510902

  4. Vapor pressures of mixtures of CFC-114 with the potential replacement coolants C{sub 4}F{sub 10} and c-C{sub 4}F{sub 8}

    SciTech Connect

    Trowbridge, L.D.; Otey, M.G.

    1994-09-01

    The U.S. Enrichment Corporation`s production of isotopically enriched uranium depends solely on two plants which utilize the gaseous diffusion process. This process uses large quantities of CFC-114 as an evaporative coolant. CFC-114, however, will be phased out of production at the end of 1995 due to its potential to deplete stratospheric ozone. A search has been underway for substitutes for a number of years. The initial search (1988-89) for an ozone-friendly, commercially available, chemically compatible substitute yielded two candidates, FC-c318 (c-C{sub 4}F{sub 8}) and FC-3110 (C{sub 4}F{sub 10}). The intended mode of replacing coolant was to stage the new coolant into independent subsystems of the plants, so that some systems would continue to operate on CFC-114, and an increasing number would operate on the new coolant. During that changeover process, the possibility of coolant mixing arises in variety of scenarios. This work was intended to generate sufficient experimental information to be able to predict the vapor pressure of coolant mixtures over the range of operating conditions likely to be found in the diffusion plants. Specifically, vapor pressures were measured over the temperature range 322 to 355 K (120{degrees}F to 180{degrees}F) and over the full range of mole fractions for binary mixtures of CFC-114 with FC-3110, and of CFC-114 with FC-c318.

  5. Acoustic Imaging Evaluation of Juvenile Salmonid Behavior in the Immediate Forebay of the Water Temperature Control Tower at Cougar Dam, 2010

    SciTech Connect

    Khan, Fenton; Johnson, Gary E.; Royer, Ida M.; Phillips, Nathan RJ; Hughes, James S.; Fischer, Eric S.; Ploskey, Gene R.

    2011-10-01

    This report presents the results of an evaluation of juvenile Chinook salmonid (Oncorhynchus tshawytscha) behavior in the immediate forebay of the Water Temperature Control (WTC) tower at Cougar Dam in 2010. The study was conducted by the Pacific Northwest National Laboratory for the U.S. Army Corps of Engineers. The overall goal of the study was to characterize juvenile salmonid behavior and movement patterns in the immediate forebay of the WTC tower for fisheries resource managers to use to make decisions on bioengineering designs for long-term structures and/or operations to facilitate safe downstream passage for juvenile salmonids. We collected acoustic imaging (Dual-Frequency Identification Sonar; DIDSON) data from February 1, 2010 through January 31, 2011 to evaluate juvenile salmonid behavior year-round in the immediate forebay surface layer of the WTC tower (within 20 m, depth 0-5 m). From October 28, 2010 through January 31, 2011 a BlueView acoustic camera was also deployed in an attempt to determine its usefulness for future studies as well as augment the DIDSON data. For the DIDSON data, we processed a total of 35 separate 24-h periods systematically covering every other week in the 12-month study. Two different 24-hour periods were processed for the BlueView data for the feasibility study. Juvenile salmonids were present in the immediate forebay of the WTC tower throughout 2010. The juvenile salmonid abundance index was low in the spring (<200 fish per sample-day), began increasing in late April and peaked in mid-May. Fish abundance index began decreasing in early June and remained low in the summer months. Fish abundance increased again in the fall, starting in October, and peaked on November 8-9. A second peak occurred on December 22. Afterwards, abundance was low for the rest of the study (through January 2011). Average fish length for juvenile salmonids during early spring 2010 was 214 {+-} 86 mm (standard deviation). From May through early November, average fish length remained relatively consistent (132 {+-} 39 mm), after which average lengths increased to 294 {+-} 145 mm for mid-November though early December. Fish behavior analysis indicates milling in front of the intake tower was the most common behavior observed throughout the study period (>50% of total fish events). The next most common movement patterns were fish traversing along the front of the tower, east-to-west and west-to-east. The proportion of fish events seen moving into (forebay to tower) or out of (tower to forebay) the tower was generally low throughout the spring, summer, and early fall for both directions combined. From mid-December 2010 through the end of the study, the combined proportions of fish moving into and out of the tower were higher than previous months of this study. Schooling behavior was most distinct in the spring from late April through mid-June. Schooling events were present in 30 - 96% of the fish events during that period, with a peak in mid-May. Schooling events were also present in the summer, but at lower numbers. Diel distributions for schooling fish during spring, fall, and winter months indicate schooling was concentrated during daylight hours. No schooling was observed at night. Predator activity was observed during late spring, when fish abundance and schooling were highest for the year, and again in the fall months when fish events increased from a summer low. No predator activity was observed in the summer, and little activity occurred during the winter months. For the two days of BlueView data analyzed for vertical distribution in the forebay, a majority of fish (>50%) were present in the middle of the water column (10 - 20 m deep). Between 20 and 41 % of total fish abundance were found in the bottom of the water column (20 - 30 m deep). Few fish were observed in the top 10 m of the water column.

  6. Underwater Laser Plasma Acoustic Source Directivity and Frequency Control Demonstration

    NASA Astrophysics Data System (ADS)

    Jones, T. G.; Hornstein, M.; Ting, A.; Nicholas, M.

    2009-11-01

    A remote underwater laser acoustic source is under development at NRL. Sound is generated by intense laser pulses propagating through air and water, followed by underwater optical compression and laser-induced breakdown (LIB). Such an acoustic source would be useful for communications, navigation, and sonar imaging. Recent experiments demonstrated control of the shape of the LIB plasma volume, and thereby control of the acoustic frequency spectrum and sound pressure level as a function of acoustic propagation direction. Femtosecond and nanosecond lasers were used for lens-focused acoustic generation near the water surface. The LIB volume shape was controlled by varying laser pulse length, energy, optical bandwidth, and focusing angle. Aspherical LIB volumes produced strongly anisotropic acoustic sources. Initial results of acoustic propagation studies in a 30,000 gallon bubbly salt water tank suggest both ultrasonic and bubble-induced attenuation. Recent results will be discussed.

  7. Holographic acoustic elements for manipulation of levitated objects.

    PubMed

    Marzo, Asier; Seah, Sue Ann; Drinkwater, Bruce W; Sahoo, Deepak Ranjan; Long, Benjamin; Subramanian, Sriram

    2015-01-01

    Sound can levitate objects of different sizes and materials through air, water and tissue. This allows us to manipulate cells, liquids, compounds or living things without touching or contaminating them. However, acoustic levitation has required the targets to be enclosed with acoustic elements or had limited manoeuvrability. Here we optimize the phases used to drive an ultrasonic phased array and show that acoustic levitation can be employed to translate, rotate and manipulate particles using even a single-sided emitter. Furthermore, we introduce the holographic acoustic elements framework that permits the rapid generation of traps and provides a bridge between optical and acoustical trapping. Acoustic structures shaped as tweezers, twisters or bottles emerge as the optimum mechanisms for tractor beams or containerless transportation. Single-beam levitation could manipulate particles inside our body for applications in targeted drug delivery or acoustically controlled micro-machines that do not interfere with magnetic resonance imaging. PMID:26505138

  8. Holographic acoustic elements for manipulation of levitated objects

    NASA Astrophysics Data System (ADS)

    Marzo, Asier; Seah, Sue Ann; Drinkwater, Bruce W.; Sahoo, Deepak Ranjan; Long, Benjamin; Subramanian, Sriram

    2015-10-01

    Sound can levitate objects of different sizes and materials through air, water and tissue. This allows us to manipulate cells, liquids, compounds or living things without touching or contaminating them. However, acoustic levitation has required the targets to be enclosed with acoustic elements or had limited manoeuvrability. Here we optimize the phases used to drive an ultrasonic phased array and show that acoustic levitation can be employed to translate, rotate and manipulate particles using even a single-sided emitter. Furthermore, we introduce the holographic acoustic elements framework that permits the rapid generation of traps and provides a bridge between optical and acoustical trapping. Acoustic structures shaped as tweezers, twisters or bottles emerge as the optimum mechanisms for tractor beams or containerless transportation. Single-beam levitation could manipulate particles inside our body for applications in targeted drug delivery or acoustically controlled micro-machines that do not interfere with magnetic resonance imaging.

  9. Broadband enhanced transmission of acoustic waves through serrated metal gratings

    NASA Astrophysics Data System (ADS)

    Qi, Dong-Xiang; Deng, Yu-Qiang; Xu, Di-Hu; Fan, Ren-Hao; Peng, Ru-Wen; Chen, Ze-Guo; Lu, Ming-Hui; Huang, X. R.; Wang, Mu

    2015-01-01

    In this letter, we have demonstrated that serrated metal gratings, which introduce gradient coatings, can give rise to broadband transmission enhancement of acoustic waves. Here, we have experimentally and theoretically studied the