Ambient pressure dependence of the subharmonic signal from ultrasound contrast microbubbles

2012 ◽  
Author(s):  
Fei Li ◽  
Tao Ling ◽  
Chengrui Liu ◽  
Qiaofeng Jin ◽  
Feiyan Cai ◽  
...  
Keyword(s):  
Pressure Dependence ◽  
Ambient Pressure ◽  
Ultrasound Contrast ◽  
Contrast Microbubbles

Dependence of the subharmonic signal from ultrasound contrast microbubbles on ambient pressure

2012 ◽  
Vol 131 (4) ◽  
pp. 3324-3324
Author(s):  
Fei Li ◽  
Tao Ling ◽  
Chengrui Liu ◽  
Qiaofeng Jin ◽  
Feiyan Cai ◽  
...  
Keyword(s):  
Ambient Pressure ◽  
Ultrasound Contrast ◽  
Contrast Microbubbles

Real-Time Excitation-Enhanced Ultrasound Contrast Imaging

2005 ◽  
Vol 27 (2) ◽  
pp. 65-74 ◽  
Author(s):  
Flemming Forsberg ◽  
William T. Shi ◽  
Michael K. Knauer ◽  
Anne L. Hall ◽  
Chris Vecchio ◽  
...  
Keyword(s):  
Real Time ◽  
Imaging Modality ◽  
Surrounding Tissue ◽  
Contrast Imaging ◽  
Maximum Enhancement ◽  
Ultrasound Contrast ◽  
Ultrasound Contrast Imaging ◽  
Contrast Microbubbles

A new nonlinear contrast specific imaging modality, excitation-enhanced imaging (EEI) has been implemented on commercially-available scanners for real-time imaging. This novel technique employs two acoustic fields: a low-frequency, high-intensity ultrasound field (the excitation field) to actively condition contrast microbubbles, and a second lower-intensity regular imaging field applied shortly afterwards to detect enhanced contrast scattering. A Logiq 9 scanner (GE Healthcare, Milwaukee, WI) with a 3.5C curved linear array and an AN2300 digital ultrasound engine (Analogic Corporation, Peabody, MA) with a P4-2 phased array transducer (Philips Medical Systems, Bothell, WA) were modified to perform EEI on a vector-by-vector basis in fundamental and pulse inversion harmonic grayscale modes. Ultrasound contrast microbubbles within an 8 mm vessel embedded in a tissue-mimicking flow phantom (ATS Laboratories, Bridgeport, CT) were imaged in vitro. While video intensities of scattered signals from the surrounding tissue were unchanged, video intensities of echoes from contrast bubbles within the vessel were markedly enhanced. The maximum enhancement achieved was 10.4 dB in harmonic mode (mean enhancement: 6.3 dB; p=0.0007). In conclusion, EEI may improve the sensitivity of ultrasound contrast imaging, but further work is required to assess the in vivo potential of this new technique.

scholarly journals Ultrasound contrast microbubbles in imaging and therapy: physical principles and engineering

2009 ◽  
Vol 54 (6) ◽  
pp. R27-R57 ◽  
Author(s):  
Shengping Qin ◽  
Charles F Caskey ◽  
Katherine W Ferrara
Keyword(s):  
Ultrasound Contrast ◽  
Physical Principles ◽  
Contrast Microbubbles

SUPPRESSION OF SPIN FLUCTUATIONS IN YMn2 BY HYDROSTATIC PRESSURE

1993 ◽  
Vol 07 (01n03) ◽  
pp. 826-829 ◽  
Author(s):  
E. BAUER ◽  
I.S. DUBENKO ◽  
E. GRATZ ◽  
R. HAUSER ◽  
A. MARKOSYAN ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Neutron Diffraction ◽  
Pressure Dependence ◽  
Ambient Pressure ◽  
Paramagnetic State ◽  
Spin Fluctuations ◽  
Interatomic Distances ◽  
Effective Moment ◽  
Large Pressure ◽  
Phase Compound

The cubic Laves phase compound YMn2 exhibits a huge spontaneous volume magnetostriction at the Néel temperature (TN=100 K). The magnetic moment per Mn atom is 2.7 μB at 2 K. From polarized neutron diffraction in the paramagnetic state it has been shown that the effective moment persisting above TN is reduced (1.6 μB at 120 K). The anomalously large pressure dependence of TN (dTN/dp=–35 K/kbar) is an evidence for the sensitive role played by the Mn—Mn interatomic distances. In the paramagnetic state, the influence of spin fluctuations dominates the physical properties. We have studied the effect of pressure on the resistivity up to 16 kbar. From dρ/dT we have estimated the spinfluctuation temperature as a function of pressure. The value at ambient pressure is 15 K which is in agreement with that determined in the paramagnetic Y0.9Lu0.1Mn2 compound.

scholarly journals Pressure dependence of the deuterium isotope effect in the photolysis of formaldehyde by ultraviolet light

2010 ◽  
Vol 10 (7) ◽  
pp. 3455-3462 ◽  
Author(s):  
E. J. K. Nilsson ◽  
V. F. Andersen ◽  
H. Skov ◽  
M. S. Johnson
Keyword(s):  
Isotope Effect ◽  
Pressure Dependence ◽  
Kinetic Isotope Effect ◽  
Ambient Pressure ◽  
Deuterium Isotope Effect ◽  
Kinetic Isotope ◽  
Molecular Channel ◽  
The University ◽  
First Time ◽  
Gas Pressures

Abstract. The pressure dependence of the relative photolysis rate of HCHO vs. HCDO has been investigated for the first time, using a photochemical reactor at the University of Copenhagen. The dissociation of HCHO vs. HCDO using a UVA lamp was measured at total bath gas pressures of 50, 200, 400, 600 and 1030 mbar. The products of formaldehyde photodissociation are either H2 + CO (molecular channel) or HCO + H (radical channel), and a photolysis lamp was chosen to emit light at wavelengths that greatly favor the molecular channel. The isotope effect in the dissociation, kHCHO/kHCDO, was found to depend strongly on pressure, varying from 1.1 + 0.15/−0.1 at 50 mbar to 1.75±0.10 at 1030 mbar. The results can be corrected for radical channel contribution to yield the kinetic isotope effect for the molecular channel; i.e. the KIE in the production of molecular hydrogen. This is done and the results at 1030 mbar are discussed in relation to previous studies at ambient pressure. In the atmosphere the relative importance of the two product channels changes with altitude as a result of changes in pressure and actinic flux. The study demonstrates that the δD of photochemical hydrogen produced from formaldehyde will increase substantially as pressure decreases.

scholarly journals Study on the Pressure Dependence of Boiling Point, Flashpoint, and Lower Flammability Limit at Low Ambient Pressure

2015 ◽  
Vol 54 (6) ◽  
pp. 1899-1907 ◽  
Author(s):  
Chao Ding ◽  
Yaping He ◽  
Jiusheng Yin ◽  
Wei Yao ◽  
Dechuang Zhou ◽  
...  
Keyword(s):  
Pressure Dependence ◽  
Boiling Point ◽  
Ambient Pressure ◽  
Flammability Limit ◽  
Lower Flammability Limit
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