scholarly journals Homogeneous bubble nucleation in water at negative pressure: A Voronoi polyhedra analysis

2013 ◽  
Vol 138 (8) ◽  
pp. 084508 ◽  
Author(s):  
Jose L. F. Abascal ◽  
Miguel A. Gonzalez ◽  
Juan L. Aragones ◽  
C. Valeriani
Keyword(s):  
Negative Pressure ◽  
Bubble Nucleation ◽  
Voronoi Polyhedra

Processing of Cellular Polyurethane by Ultrasonic Excitation

1992 ◽  
Vol 114 (3) ◽  
pp. 323-328 ◽  
Author(s):  
H. Park ◽  
J. R. Youn
Keyword(s):  
Size Distribution ◽  
Bubble Size ◽  
Negative Pressure ◽  
Bubble Nucleation ◽  
High Rate ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Foam Structure ◽  
Pressure Equilibrium ◽  
Theoretical Results

Processing of cellular polyurethane was investigated experimentally and theoretically to examine the possibility of ultrasonic foaming. Polyol resin was supersaturated with nitrogen and ultrasonic excitation was applied for copious bubble nucleation. The ultrasonic excitation resulted in good foam structure whose size distribution was uniform and less than 100 μm. The ultrasonic excitation was modelled by utilizing the classical nucleation theory to predict the rate of nucleation. Theoretical results suggest that a high rate of nucleation will be obtained if the ultrasonic excitation generates large enough negative pressure. Final bubble size was calculated by considering the pressure equilibrium between inside and outside of the bubble.

scholarly journals Cavitation and Negative Pressure: A Flexible Water Model Molecular Dynamics Simulation

2019 ◽  
Vol 8 (2) ◽  
pp. 172 ◽  
Author(s):  
Gang Liu ◽  
Qiang Fu ◽  
Junjun Kang
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bonds ◽  
Potential Energy ◽  
Negative Pressure ◽  
Room Temperature ◽  
Md Simulations ◽  
Bubble Nucleation ◽  
Dynamics Simulation ◽  
Water Model ◽  
Bubble Generation

The critical negative pressure for cavitation in water has been theoretically predicted to be in the range of -100 to -200 MPa at room temperature, whereas values around -30 MPa have been obtained by many experiments. The discrepancy has yet to be resolved. Molecular dynamics (MD) is an effective method of observing bubble nucleation, however, most MD simulations use a rigid water model and do not take the effects of intermolecular vibrations into account. In this manuscript we perform MD simulations to study cavitation in water by using a TIP4P/2005f model under volumecontrolled stretching. It is found that the critical negative pressure of water was -168 MPa in the simulation and the critical negative pressure of water containing 50 oxygen molecules was -150 MPa. Hydrogen bonds played a major role in the cavitation process: the breaking of hydrogen bonds promoted bubble generation and growth. The O-H bond could release energy to increase the amount of potential energy in the system, so that cavitation was more likely to occur. When cavitation occurred, the O-H bond could absorb energy to reduce the amount of potential energy in the system, which will promote the growth of bubbles, and stabilise the cavitation bubbles.

Blood Flow, Negative Pressure, and Hemolysis During Hemodialysis

1999 ◽  
Vol 3 (1) ◽  
pp. 45-50
Author(s):  
Zbylut J. Twardowski ◽  
Jimmy D. Haynie ◽  
Harold L. Moore
Keyword(s):  
Blood Flow ◽  
Negative Pressure

Negative pressure therapy – How many dressing changes are enough?

2012 ◽  
Vol 60 (S 01) ◽  
Author(s):  
S Raab ◽  
T Weimann ◽  
W Sienel ◽  
L Lampl ◽  
M Beyer
Keyword(s):  
Negative Pressure ◽  
Negative Pressure Therapy ◽  
Pressure Therapy

Prevention of poststernotomy wound infections in obese patients by negative pressure wound therapy

2013 ◽  
Vol 61 (S 01) ◽  
Author(s):  
O Grauhan ◽  
A Navasardyan ◽  
M Hofmann ◽  
P Müller ◽  
J Stein ◽  
...  
Keyword(s):  
Negative Pressure ◽  
Negative Pressure Wound Therapy ◽  
Obese Patients ◽  
Wound Infections ◽  
Wound Therapy

Experience of negative pressure wound therapy over sternal wound healing: A retrospective review

WCET Journal ◽  
2019 ◽  
Vol 39 (2) ◽  
pp. 9-18
Author(s):  
Wai Sze Ho ◽  
Wai Kuen Lee ◽  
Ka Kay Chan ◽  
Choi Ching Fong
Keyword(s):  
Wound Healing ◽  
Negative Pressure ◽  
Negative Pressure Wound Therapy ◽  
Assessment Tool ◽  
Wound Care ◽  
Wound Therapy ◽  
Treatment Pathways ◽  
Wound Assessment ◽  
One Year

Objectives The aim of this study was to retrospectively review the effectiveness of negative pressure wound therapy (NPWT) in sternal wound healing with the use of the validated Bates-Jensen Wound Assessment Tool (BWAT), and explore the role of NPWT over sternal wounds and future treatment pathways. Methods Data was gathered from patients' medical records and the institution's database clinical management system. Seventeen subjects, who had undergone cardiothoracic surgeries and subsequently consulted the wound care team in one year were reviewed. Fourteen of them were included in the analysis. Healing improvement of each sternal wound under continuous NPWT and continuous conventional dressings was studied. In total, 23 continuous NPWT and 13 conventional dressing episodes were analysed with the BWAT. Results Among conventional dressing episodes, sternal wound improvement was 2.5–3% over 10 days to 3.5 weeks, whereas 4–5% sternal healing was achieved in 5 days to 2 weeks with sternal wire presence. Better healing at 11% in 1 week by conventional dressing was attained after sternal wire removal. In NPWT episodes, 8–29%, 13–24%, and 15–46% of healing was observed in 2 weeks, 3.5 to 5 weeks and 6 to 7 weeks, respectively. Only 39% wound healing was acquired at the 13th week of NPWT in one subject. With sternal wire present, 6%–29% wound healing progress was achieved by NPWT in 1–4 weeks, and 16–23% wound improvement in 2 to 4.5 weeks by NWPT after further surgical debridement. After sternal wire removal, 6–34% sternal wound healing occurred by continuous NPWT for 1–2 weeks, and maximum healing at 46% after 2.5 weeks of NPWT were observed. Conclusions Better wound healing was achieved in the NPWT group in comparison to conventional dressings alone. However, suboptimal sternal wound healing by NPWT alone was observed. Removal of sternal wire may improve the effectiveness of NPWT. Successful tertiary closure after NPWT among subjects supports the important bridging role of NPWT in sternal wound healing. Factors causing stagnant sternal wound healing by NPWT alone are discussed.

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