Elastic characteristics of the lung perivascular interstitial space

1983 ◽  
Vol 54 (6) ◽  
pp. 1717-1725 ◽  
Author(s):  
J. C. Smith ◽  
W. Mitzner
Keyword(s):  
Elastic Properties ◽  
Lung Volume ◽  
Interstitial Space ◽  
Elastic Behavior ◽  
Published Data ◽  
Fluid Accumulation ◽  
Recoil Pressure ◽  
Vascular Walls ◽  
Isolated Lung ◽  
Volume History

An analysis of the elastic behavior of the lung perivascular interstitial space during interstitial fluid accumulation is presented. Fluid accumulation must deform the lung parenchyma and vascular walls that form the interstitial space boundaries. The deformations of these boundaries are predicted from previously published data on the elastic properties of the boundary materials. The analysis gives the relationships among the elastic properties of the boundaries, the compliance of the interstitium, the lung volume, and the lung elastic recoil pressure. Values of the interstitial compliance are predicted to decrease with increasing lung recoil pressure and are dependent on the lung pressure-volume history. At low recoil pressures over 70% of the interstitial compliance results from deformation of the parenchyma. As the recoil pressure increases, either with increasing lung volume or due to the lung pressure-volume history, the contributions of the parenchymal and vascular wall deformations become similar. The predictions are generally consistent with published data on interstitial compliance obtained from measurements of isolated lung weight gain during vascular fluid transudation. This correlation suggests that the elastic behavior of the interstitial space can be accounted for by the known elastic properties of the boundary materials.

Relations among recoil pressure, surface area, and surface tension in the lung

1981 ◽  
Vol 50 (5) ◽  
pp. 921-930 ◽  
Author(s):  
T. A. Wilson
Keyword(s):  
Surface Tension ◽  
Surface Energy ◽  
Total Energy ◽  
Surface Area ◽  
Lung Volume ◽  
Mechanical Energy ◽  
Energy Difference ◽  
Published Data ◽  
Recoil Pressure ◽  
Pressure Surface

The difference between energy stored in air- and saline-filled lungs is the sum of surface energy and the energy of tissue distortion caused by surface tension. The surface energy is zeta gamma dS, where gamma is surface tension and S is surface area. There is no corresponding relation between tissue energy and measurable variables. However, two equations can be obtained from the expression for the total energy difference. One is the statement that the total energy of the lung is minimum at equilibrium, and the other is the statement of conservation of mechanical energy as lung volume changes. The expression for tissue energy is eliminated between the two equations to obtain a single relation among the variables of interest: recoil pressure, surface area, and surface tension. Published data on recoil pressure and surface area of saline-filled, air-filled, and detergent-washed rabbit lungs are used in these equations to determine surface tension as a function of lung volume. The values of surface tension deduced from this analysis are lower than the values that would be obtained if the additional tissue forces in the air-filled lung were neglected. The contribution of tissue forces to the added recoil of the air-filled lung increases with increasing lung volume and accounts for approximately half the additional recoil at high lung volume.

Effect of lung volume history on rate of edema formation in isolated canine lobe

1978 ◽  
Vol 45 (6) ◽  
pp. 880-884 ◽  
Author(s):  
H. S. Goldberg
Keyword(s):  
Weight Gain ◽  
Hydrostatic Pressure ◽  
Lung Volume ◽  
Interstitial Fluid ◽  
Venous Pressure ◽  
Transpulmonary Pressure ◽  
Fluid Accumulation ◽  
Edema Formation ◽  
Lung Inflation ◽  
Volume History

The effect of lung volume history and prior accumulation of interstitial fluid on rate of edema formation in isolated canine lobes was investigated. Mean pulmonary artery pressure and mean pulmonary venous pressure were kept constant at 40 and 30 cmH2O, respectively. Transpulmonary pressure (Ptp) was varied among 5, 15, and 25 cmH2O by progressive stepwise inflation and deflation. Rate of fluid accumulation was estimated by changes in slow weight gain after a change in Ptp. Although there is continuous interstitial fluid accumulation over the course of the experiment the results indicate that interstitial hydrostatic pressure around leaky vessels at Ptp of 15 cmH2O is reduced by prior lung inflation to Ptp of 25 cmH2O and increased by prior deflation to Ptp of 5 cmH2O. These results suggest that the distribution of interstitial fluid may vary as a function of lung volume history.

Breathing at low lung volumes and chest strapping: a comparison of lung mechanics

1981 ◽  
Vol 50 (3) ◽  
pp. 650-657 ◽  
Author(s):  
N. J. Douglas ◽  
G. B. Drummond ◽  
M. F. Sudlow
Keyword(s):  
Lung Volume ◽  
Maximum Flow ◽  
Normal Subjects ◽  
Lung Mechanics ◽  
Lung Volumes ◽  
Flow Rates ◽  
Recoil Pressure ◽  
Forced Expiratory Flow ◽  
Expiratory Flow ◽  
Expiratory Flow Rates

In six normal subjects forced expiratory flow rates increased progressively with increasing degrees of chest strapping. In nine normal subjects forced expiratory flow rates increased with the time spent breathing with expiratory reserve volume 0.5 liters above residual volume, the increase being significant by 30 s (P less than 0.01), and flow rates were still increasing at 2 min, the longest time the subjects could breathe at this lung volume. The increase in flow after low lung volume breathing (LLVB) was similar to that produced by strapping. The effect of LLVB was diminished by the inhalation of the atropinelike drug ipratropium. Quasistatic recoil pressures were higher following strapping and LLVB than on partial or maximal expiration, but the rise in recoil pressure was insufficient to account for all the observed increased in maximum flow. We suggest that the effects of chest strapping are due to LLVB and that both cause bronchodilatation.

A model for mechanical structure of the alveolar duct

1982 ◽  
Vol 52 (4) ◽  
pp. 1064-1070 ◽  
Author(s):  
T. A. Wilson ◽  
H. Bachofen
Keyword(s):  
Surface Tension ◽  
Lung Volume ◽  
Published Data ◽  
Scanning Electron Micrographs ◽  
Fiber System ◽  
Lung Capacity ◽  
Alveolar Duct ◽  
Tissue System ◽  
Line Elements ◽  
Air Liquid Interface

The appearance of the microstructure of the lung as revealed in transmission and scanning electron micrographs of perfusion-fixed air- and saline-filled lungs suggests the following model for the structure of the alveolar duct. There are two networks of force-bearing elements. The first is an interdependent part of the peripheral connective tissue system that starts from the pleura and extends into the interlobar and interlobular fissures. At the sublobular level, its geometry is not yet fully clear. This network is extended by changes in lung volume and is insensitive to surface tension. The second network is composed of the line elements that form the rims of the alveolar openings. This network is the terminal part of the axial fiber system that surrounds bronchi, bronchioli, and arteries. The line elements of this network are extended by the outward force of surface tension. The two-dimensional alveolar walls that form the alveoli are negligible mechanical components except as platforms for surface tension at the air-liquid interface. An analysis of the mechanics of this model yields relations among surface area, recoil pressure, lung volume, and surface tension that are consistent with published data for lung volumes below 80% of total lung capacity.

scholarly journals Depositional and Diagenetic Controls on Macroscopic Acoustic and Geomechanical Behaviors in Wufeng-Longmaxi Formation Shale

2021 ◽  
Vol 9 ◽  
Author(s):  
Jixin Deng ◽  
Chongyi Wang ◽  
Qun Zhao ◽  
Wei Guo ◽  
Genyang Tang ◽  
...  
Keyword(s):  
Elastic Properties ◽  
Failure Modes ◽  
Elastic Behavior ◽  
Compositional Variation ◽  
Primary Control ◽  
Longmaxi Formation ◽  
Young’S Moduli ◽  
Splitting Failure ◽  
Quartz Cement ◽  
Geochemical Analyses

This integrated study provides significant insight into parameters controlling the dynamic and static elastic behaviors of shale. Acoustic and geomechanical behaviors measurement from laboratory have been coupled with detailed petrographic and geochemical analyses, and microtexture observations on shale samples from the Wufeng−Longmaxi Formation of the southeast Sichuan Basin. The major achievement is the establishment of the link between depositional environment and the subsequent microtexture development, which exerts a critical influence on the elastic properties of the shale samples. Microtexture and compositional variation between upper and lower sections of the Wufeng−Longmaxi Formation show that the former undergoes normal mechanical and chemical compaction to form clay supported matrices with apparent heterogonous mechanical interfaces between rigid clasts and the aligned clay fabric. Samples from lower sections exhibited a microcrystalline quartz-supported matrix with a homogeneous mechanical interface arising from syn-depositional reprecipitation of biogenic quartz cement. This type of microtexture transition exerts primary control on elastic behavior of the shale samples. A clear “V” shaped trend observed from acoustic velocities and static Young’s moduli document contrasting roles played by microtexture, porosity and organic matter in determining elastic properties. Samples with a quartz-supported matrix exhibit elastic deformation and splitting failure modes. The increment of the continuous biogenic quartz cemented medium with limited mechanic interface. By contrast, samples showing a predominantly clay-supported matrix exhibited more signs of plastic deformation reflecting heterogeneous mechanical interfaces at grain boundaries.

Measurement of Scattering Coefficients

2011 ◽  
Author(s):  
Dale Chimenti ◽  
Stanislav Rokhlin ◽  
Peter Nagy
Keyword(s):  
Wave Propagation ◽  
Reflection Coefficient ◽  
Transmission Coefficient ◽  
Elastic Properties ◽  
Volume Fraction ◽  
Ultrasonic Field ◽  
Guided Wave ◽  
Scattering Coefficient ◽  
Elastic Behavior ◽  
Scattering Coefficients

In the previous chapters, we saw how waves in composites behaved under various circumstances, depending on material anisotropy and wave propagation direction. The most important function that describes guided wave propagation, and the plate elastic behavior on which propagation depends, is the reflection coefficient (RC) or transmission coefficient (TC). More generally, we can call either one simply, the scattering coefficient (SC). It is clear that the elastic properties of the composite are closely tied to the SC, and in turn the scattering coefficient determines the dispersion spectrum of the composite plate. Measuring the SC provides a route to the inference of the elastic properties. To measure the SC, we need only observe the reflected or transmitted ultrasonic field of the incident acoustic energy. In doing so, however, the scattered ultrasonic field is influenced by several factors, both intrinsic and extrinsic. Clearly, the scattered ultrasonic field of an incident acoustic beam falling on the plate from a surrounding or contacting fluid will be strongly influenced by the RC or TC of the plate material. The scattering coefficients are in turn dependent on the plate elastic properties and structural composition: fiber and matrix properties, fiber volume fraction, layup geometry, and perhaps other factors. These elements are not, however, the only ones to determine the amplitude and spatial distribution of energy in the scattered ultrasonic field. Extrinsic factors such as the finite transmitting and receiving transducers, their focal lengths, and their placement with respect to the sample under study can make contributions to the signal as important as the SC itself. Therefore, a systematic study of the role of the transducer is essential for a complete understanding and correct interpretation of acoustic signals in the scattered field. The interpretation of these signals leads ultimately to the inference of composite elastic properties. As we pointed out in Chapter 5, the near coincidence under some conditions of guided plate wave modes with the zeroes of the reflection coefficient (or peaks in the transmission coefficient) has been exploited many times to reveal the plate’s guided wave mode spectrum.

scholarly journals The Use of a Virtual Patient to Follow Pleural Pressure Changes Associated with Therapeutic Thoracentesis

2017 ◽  
Vol 40 (12) ◽  
pp. 690-695 ◽  
Author(s):  
Tomasz Gólczewski ◽  
Anna M. Stecka ◽  
Marcin Michnikowski ◽  
Elżbieta M. Grabczak ◽  
Piotr Korczyński ◽  
...  
Keyword(s):  
Respiratory System ◽  
Lung Volume ◽  
Clinical Studies ◽  
Virtual Patient ◽  
Pleural Pressure ◽  
Model Parameters ◽  
Medical Problems ◽  
Physiological Factors ◽  
Recoil Pressure ◽  
Pressure Changes

Purpose Influence of therapeutic thoracentesis on the pleural pressure (Pp) has been discussed in many clinical studies, however reasons of Pp changes are not precisely established. The aim of the study was to use a previously elaborated virtual cardiopulmonary patient (VP) in analysis of impact of physiological factors on Pp during the procedure. Methods Simulations were performed on VP with default values of parameters for which VP simulated the respiratory system of the average 50-year-old healthy Polish woman according to spirometric examination. Alterations of Pp and the amplitude of Pp changes related to breathing (AP) were analyzed. Model parameters related to chosen factors were deviated from their default values to analyze the degree of their impact on Pp and AP. The analysis was based on and supported by our own clinical data. Results The Pp and AP alteration intensity appeared to be most sensitive to the compliances of the rib cage and mediastinum, and the nonlinearity of the dependence between the recoil pressure and the lung volume: the lower the compliances and the higher the nonlinearity were, the deeper the Pp fall during the procedure and the bigger the AP increase were observed. Conclusions Experiments in silico are very useful in analyzing sophisticated physiological and medical problems. They made it possible to show which factors are particularly responsible for changes in Pp during thoracentesis. In the future, they may be useful in establishing objective conditions under which thoracentesis needs to be stopped.

Analysis of the Scatter of the Elastic Properties in Conventionally Cast Nickel Base Superalloys: Quantification, Modeling and Evaluation of the Impact on Gas Turbine Blade Design

2014 ◽  
Author(s):  
Andrea Riva ◽  
Andrea Bessone
Keyword(s):  
Gas Turbine ◽  
Young’S Modulus ◽  
Elastic Properties ◽  
Young's Modulus ◽  
Turbine Blades ◽  
Mode Shapes ◽  
Elastic Behavior ◽  
Nickel Base Superalloys ◽  
Nickel Base ◽  
The Impact

Cast nickel-base superalloys elastic properties have a very large scatter, mainly because of the coarse grain microstructure and in-grain anisotropy. This high dispersion must be taken into account in the design of gas turbine blades, in particular when evaluating phenomena directly linked to the elastic behavior, such as blades vibration. This source of elastic properties scatter becomes even more important on specimens for material characterization because of their inferior size, which entails a lesser number of grains (i.e. a larger scatter). In this paper a model aimed to quantify such scatter is proposed. The performances of the model in predicting the standard deviation of the Young’s modulus (and consequently of the eigenfrequencies) are also shown, both for tested specimens and blades excited on clamps. Finally, a sensitivity FEM modal analysis is performed in order to evaluate how the elastic property dispersion might affect the blade eigenfrequencies and the relative mode shapes, with particular emphasis on the case of a specific region of a geometrically complex component affected by an anomalous Young’s modulus. Besides, the influence of the blade mass is evaluated through both experimental clamp impact tests and FEM analyses. The effect on blades of such source of scatter is then compared to the effect of the elastic properties dispersion. ANSYS program has been used for the simulations.

scholarly journals An Efficient Approach of Predicting the Elastic Property of Hydrating Cement Paste

2021 ◽  
Vol 8 ◽  
Author(s):  
Baoyu Ma ◽  
Guansuo Dui ◽  
Zhenglin Jia ◽  
Bo Yang ◽  
Chunyan Yang ◽  
...  
Keyword(s):  
Elastic Properties ◽  
Cement Paste ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Empirical Method ◽  
Elastic Behavior ◽  
Engineering Practice ◽  
Proposed Model ◽  
Hydration Model ◽  
Semi Empirical

Although elastic properties of hydrating cement paste are crucial in concrete engineering practice, there are only a few widely available models for engineers to predict the elastic behavior of hydrating cement paste. Therefore, in this paper, we derive an analytical model to efficiently predict the elastic properties (e.g., Young’s modulus) of hydrating cement paste. Notably, the proposed model provides the prediction of hydration, percolation, and homogenization of the cement paste, enabling the study of the early age elasticity evolution in cement paste. A hydration model considering the mineral composition and the initial w/c ratio was used, while the percolation threshold was calculated adopting a phenomenological semi-empirical method describing the effects of the solid volume fraction and the w/c ratio. An efficient mixing rule based on the degree of solid connectivity was then adopted to calculate the elastic properties of the hydrating cement paste. Moreover, for ordinary Portland cement, a simplified model was built using Powers’ hydration model. The obtained modeling results are following experimental data and other numerical results available in the literature.

scholarly journals Promising Bialkali Bismuthides Cs(Na, K)2Bi for High-Performance Nanoscale Electromechanical Devices: Prediction of Mechanical and Anisotropic Elastic Properties under Hydrostatic Tension and Compression and Tunable Auxetic Properties

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2739
Author(s):  
Shahram Yalameha ◽  
Zahra Nourbakhsh ◽  
Ali Ramazani ◽  
Daryoosh Vashaee
Keyword(s):  
Elastic Properties ◽  
Poisson’S Ratio ◽  
High Performance ◽  
Hydrostatic Compression ◽  
Poisson's Ratio ◽  
Elastic Behavior ◽  
Hydrostatic Tension ◽  
Tension And Compression ◽  
Electromechanical Devices ◽  
Anisotropic Elastic

Using first-principles calculations, we predict highly stable cubic bialkali bismuthides Cs(Na, K)2Bi with several technologically important mechanical and anisotropic elastic properties. We investigate the mechanical and anisotropic elastic properties under hydrostatic tension and compression. At zero pressure, CsK2Bi is characterized by elastic anisotropy with maximum and minimum stiffness along the directions of [111] and [100], respectively. Unlike CsK2Bi, CsNa2Bi exhibits almost isotropic elastic behavior at zero pressure. We found that hydrostatic tension and compression change the isotropic and anisotropic mechanical responses of these compounds. Moreover, the auxetic nature of the CsK2Bi compound is tunable under pressure. This compound transforms into a material with a positive Poisson’s ratio under hydrostatic compression, while it holds a large negative Poisson’s ratio of about −0.45 along the [111] direction under hydrostatic tension. An auxetic nature is not observed in CsNa2Bi, and Poisson’s ratio shows completely isotropic behavior under hydrostatic compression. A directional elastic wave velocity analysis shows that hydrostatic pressure effectively changes the propagation pattern of the elastic waves of both compounds and switches the directions of propagation. Cohesive energy, phonon dispersion, and Born–Huang conditions show that these compounds are thermodynamically, mechanically, and dynamically stable, confirming the practical feasibility of their synthesis. The identified mechanisms for controlling the auxetic and anisotropic elastic behavior of these compounds offer a vital feature for designing and developing high-performance nanoscale electromechanical devices.

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