scholarly journals Ambient pressure sensitivity of microbubbles investigated through a parameter study

2009 ◽  
Vol 126 (6) ◽  
pp. 3350-3358 ◽  
Author(s):  
Klaus Scheldrup Andersen ◽  
Jørgen Arendt Jensen
Keyword(s):  
Ambient Pressure ◽  
Parameter Study ◽  
Pressure Sensitivity

scholarly journals Improvement of Detection Sensitivity of Microbubbles as Sensors to Detect Ambient Pressure

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4083 ◽  
Author(s):  
Fei Li ◽  
Deyu Li ◽  
Fei Yan
Keyword(s):  
Scattering Amplitude ◽  
Ambient Pressure ◽  
Pressure Variation ◽  
Detection Sensitivity ◽  
Mechanical Index ◽  
Pressure Sensitivity ◽  
Acoustic Parameters ◽  
Promising Tool ◽  
Noninvasive Estimation ◽  
The Media

Microbubbles are considered a promising tool for noninvasive estimation of local blood pressure. It is reported that the subharmonic scattering amplitude of microbubbles decreases by 9 to 12 dB when immersed in the media under an ambient pressure variation from 0 to 180 mmHg. However, the pressure sensitivity still needs to be improved to satisfy clinical diagnostic requirements. Here, we investigated the effects of acoustic parameters on the pressure sensitivity of microbubbles through measuring the acoustic attenuation and scattering properties of commercially available SonoVue microbubbles. Our results showed that the first harmonic, subharmonic, and ultraharmonic amplitudes of microbubbles were reduced by 6.6 dB, 10.9 dB, and 9.3 dB at 0.225 mechanical index (MI), 4.6 dB, 19.8 dB, and 12.3 dB at 0.25 MI, and 18.5 dB, 17.6 dB, and 12.6 dB at 0.3 MI, respectively, when the ambient pressure increased from 0 to 180 mmHg. Our finding revealed that a moderate MI (0.25–0.4) exciting microbubbles could significantly improve their sensitivities to detect ambient pressure.

Abstract 15714: Intra-cardiac Pressure Estimation Using Subharmonic Aided Pressure Estimation (SHAPE) - A Clinical Evaluation

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Cara Esposito ◽  
Michael P Savage ◽  
Praveen Mehrotra ◽  
Ira Cohen ◽  
David L Fischman ◽  
...  
Keyword(s):  
Cardiac Catheterization ◽  
Ambient Pressure ◽  
Ultrasound Contrast Agents ◽  
Pressure Sensitivity ◽  
Left Heart ◽  
Pressure Data ◽  
Left And Right ◽  
Pressure Estimation ◽  
Catheterization Procedure ◽  
Pressure Catheter

Introduction: Subharmonic aided pressure estimation (SHAPE) utilizes ambient pressure sensitivity of subharmonic signals from ultrasound contrast agents. The objective was to evaluate SHAPE with Definity (Lantheus Medical Imaging, Inc.) and Sonazoid (GE Healthcare) microbubbles for intra-cardiac pressure estimation. Hypothesis: Errors between SHAPE and pressures obtained during cardiac catheterization ≤ 5 mmHg. Methods: IRB approved this study. Consenting patients received an infusion of Definity (56 patients; 2 vials in 50 mL of saline; infusion rate: 4-10 mL/min) or Sonazoid (77 patients; rate (mL/hour) = 0.18 x weight in kg co-infused with saline at 120 mL/hour) during cardiac catheterization. Subharmonic data was acquired using a SonixTablet (PA 4/2 array; BK Ultrasound) synchronously with pressures from the left and right ventricles and the aorta (for left heart catheterizations only). Subharmonic data (in dB) was converted to pressure values (in mmHg) using calibration factors (mmHg/dB) based on data obtained from the aorta - utilizing pressures from the aorta either during the catheterization procedure or pressures obtained using a SphygmoCor (AtCor Medical Pty. Ltd.) device after the catheterization procedure. Clinically relevant pressures between the SHAPE technique and the pressure catheter were compared. Results: Correlation coefficient between the subharmonic and pressure data was -0.8 ± 0.1. With Definity, mean absolute errors ranged from 2.9 ± 1.5 to 5.0 ± 4.2 mmHg and from 4.4 ± 5.7 to 23.7 ± 28.3 mmHg for calibration factors utilizing aortic pressures from pressure catheter and SphygmoCor, respectively. For Sonazoid microbubbles, these errors ranged from 7.9 ± 12.0 to 10.1 ± 12.4 mmHg and from 7.2 ± 11.5 to 15.0 ± 23.2 mmHg, respectively. Two adverse events occurred during Definity infusion; these were resolved with return to baseline conditions. Conclusion: SHAPE may be useful for estimating intra-cardiac pressures noninvasively.

Environmental microscopy of capillary stress-induced strain behavior in ambient-pressure aerogels

1996 ◽  
Vol 54 ◽  
pp. 850-851
Author(s):  
Sudeep M. Rao ◽  
Joshua Samuel ◽  
Sai S. Prakash ◽  
C. Jeffrey Brinker
Keyword(s):  
Silica Aerogel ◽  
Ambient Pressure ◽  
Drying Shrinkage ◽  
Pore Filling ◽  
Silica Network ◽  
Strain Behavior ◽  
Partially Saturated ◽  
Capillary Stress ◽  
Wetting Liquid ◽  
Aerogel Films

Ambient pressure silica aerogel thin films have recently been prepared by exploiting reversible drying shrinkage caused by derivatization of the internal gel surface. Aerogels have porosities of upto 99.9% and due to the small size of the pores (few nanometers), large capillary stresses are produced in gels that are partially saturated with a wetting liquid. As a result of these capillary stresses, the flexible silica network undergoes strain which has been observed using environmental microscopy. This technique allows variation of the equilibrium vapor pressure and temperature, and a simultaneous monitoring of the deformation of the unconstrained film thickness. We have observed >600% deformation during the pore-filling and pore-emptying cycles. In this presentation, we discuss the unique stress-strain behavior of these films.Ref.: Sai S. Prakash, C. Jeffrey Brinker, Alan J. Hurd & Sudeep M. Rao, "Silica aerogel films prepared at ambient pressure by using surface derivatization to induce reversible drying shrinkage", Nature. Vol. 374, 30 March, 1995, 439-443.

ON MAGNETIC PROPERTIES 0F (TMTSF)2PF6AT AMBIENT PRESSURE

1983 ◽  
Vol 44 (C3) ◽  
pp. C3-1001-C3-1005
Author(s):  
S. Iwabuchi ◽  
H. Fukuyama
Keyword(s):  
Magnetic Properties ◽  
Ambient Pressure

NEAR-WALL CHARACTERISTICS OF AN IMPINGING GASOLINE SPRAY AT INCREASED AMBIENT PRESSURE AND WALL TEMPERATURE

2009 ◽  
Vol 19 (11) ◽  
pp. 997-1012 ◽  
Author(s):  
Jochen Stratmann ◽  
D. Martin ◽  
P. Unterlechner ◽  
R. Kneer
Keyword(s):  
Wall Temperature ◽  
Ambient Pressure ◽  
Near Wall

Effect of ambient pressure on low-density nozzle plumes

1995 ◽  
Author(s):  
Chan-Hong Chung ◽  
Kenneth D ◽  
Robert Stubbs
Keyword(s):  
Ambient Pressure ◽  
Low Density

Influence of intramolecular interactions on carbon dioxide gas adsorption capacity in Mesoporous Imine polymers

2018 ◽  
Author(s):  
Jaya Prakash Madda ◽  
Pilli Govindaiah ◽  
Sushant Kumar Jena ◽  
Sabbhavat Krishna ◽  
Rupak Kishor
Keyword(s):  
Carbon Dioxide ◽  
Adsorption Capacity ◽  
Density Functional ◽  
Gas Adsorption ◽  
Ambient Pressure ◽  
Condensation Reaction ◽  
Intramolecular Interactions ◽  
Carbon Dioxide Adsorption ◽  
Nitrogen Gas ◽  
Adsorption Characteristic

<p>Covalent organic Imine polymers with intrinsic meso-porosity were synthesized by condensation reaction between 4,4-diamino diphenyl methane and (para/meta/ortho)-phthaladehyde. Even though these polymers were synthesized from precursors of bis-bis covalent link mode, the bulk materials were micrometer size particles with intrinsic mesoporous enables nitrogen as well as carbon dioxide adsorption in the void spaces. These polymers were showed stability up to 260<sup>o</sup> centigrade. Nitrogen gas adsorption capacity up to 250 cc/g in the ambient pressure was observed with type III adsorption characteristic nature. Carbon dioxide adsorption experiments reveal the possible terminal amine functional group to carbamate with CO<sub>2</sub> gas molecule to the polymers. One of the imine polymers, COP-3 showed more carbon dioxide sorption capacity and isosteric heat of adsorption (Q<sub>st</sub>) than COP-1 and COP-2 at 273 K even though COP-3 had lower porosity for nitrogen gas than COP-1 and COP-2. We explained the trends in gas adsorption capacities and Qst values as a consequence of the intra molecular interactions confirmed by Density Functional Theory computational experiments on small molecular fragments.</p>

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