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.

Surface tension-surface area curves calculated from pressure-volume loops

1982 ◽  
Vol 53 (6) ◽  
pp. 1512-1520 ◽  
Author(s):  
T. A. Wilson
Keyword(s):  
Surface Tension ◽  
Surface Area ◽  
Lung Volume ◽  
Energy Analysis ◽  
Curve Surface ◽  
Tissue Component ◽  
Recoil Pressure ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Limiting Value

An energy analysis and data from the literature on the relation among surface area, recoil pressure, and lung volume are used to calculate the surface tension-surface area curves corresponding to pressure-volume loops. The energy analysis has been described earlier (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 50: 921–926, 1981). It is based on the assumption that the tissue structure of the lung constitutes a conservative mechanical system and hence that pressure-volume hysteresis is primarily a result of surface tension-surface area hysteresis. Unlike previous methods of calculating surface tension from recoil pressure, this method does not rely on the assumption that the tissue component of recoil in the air-filled lung is the same as recoil pressure of the saline-filled lung at the same lung volume. The calculated values of surface tension decrease to less than 2 dyn/cm as surface area decreases along the deflation limb of the pressure-volume curve. Surface tension increases very steeply with surface area on the inflation limbs, reaching a limiting value of just under 30 dyn/cm. The shape of the surface tension-surface area curves, unlike the shape of the curves calculated by previous methods, is similar to the shape obtained on surface tension balances for fluid extracted from lungs.

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.

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.

Effect of lung surface tension on bronchial collapsibility in excised dog lungs

1979 ◽  
Vol 47 (4) ◽  
pp. 692-700 ◽  
Author(s):  
M. Nakamura ◽  
H. Sasaki ◽  
T. Takishima
Keyword(s):  
Surface Tension ◽  
Lung Volume ◽  
Lung Parenchyma ◽  
Recoil Pressure

Bronchial collapsibilities were studied in air- and saline-filled excised dog lungs. The intrapulmonary bronchi were isolated from the rest of the lung parenchyma with beads placed at their tributary bronchi as described previously by Takishima et al. (J. Appl. Physiol. 38: 875–881, 1975). Pressure-volume relations of the isolated bronchi were obtained while lung volume (VL) was kept constant. When lung recoil pressure (PL) was reduced by filling the lung with saline at a given VL, bronchial areas were smaller and bronchial collapsibilities were larger than in the air-filled lung. When bronchial areas and bronchial collapsibilities in air- and saline-filled lungs were compared at a given PL, they were approximately identical. We concluded that bronchial areas and collapsibilities were primarily determined by PL rather than VL, and lung surface tension itself made bronchial collapsibility equal to or even less than the degree of collapsibility due to forces applied from surrounding lung tissues that distended the bronchi.

Retraction of large liquid strips

2015 ◽  
Vol 778 ◽  
Author(s):  
Cunjing Lv ◽  
Christophe Clanet ◽  
David Quéré
Keyword(s):  
Surface Tension ◽  
Surface Energy ◽  
Surface Area ◽  
Driving Force ◽  
Large Scale ◽  
Horizontal Surface

We study the behaviour of elongated puddles deposited on non-wetting substrates. Such liquid strips retract and adopt circular shapes after a few oscillations. Their thickness and horizontal surface area remain constant during this reorganization, so that the energy of the system is only lowered by minimizing the length of the contour (and the corresponding surface energy); despite the large scale of the experiments (several centimetres), motion is driven by surface tension. We focus on the retraction stage, and show that its velocity results from a balance between the capillary driving force and inertia, due to the frictionless motion on non-wetting substrates. As a consequence, the retraction velocity has a special Taylor–Culick structure, where the puddle width replaces the usual thickness.

scholarly journals On the theory of capillarity

1908 ◽  
Vol 81 (544) ◽  
pp. 21-25 ◽  
Keyword(s):  
Surface Tension ◽  
Surface Energy ◽  
Total Energy ◽  
Internal Energy ◽  
Absolute Temperature ◽  
Heat Energy ◽  
Thermodynamic Equation ◽  
Available Energy ◽  
Capillary Phenomena

1. The fundamental quantities in the theory of capillary phenomena are the surface-tension γ (which we shall suppose expressed in dynes per centimetre), and the surface-energy λ (which we shall suppose expressed in ergs per square centimetre). The relation between these two quantities is at once given by the thermodynamic equation connecting available energy with total energy: it is therefore γ = λ + T d γ/ d T, where T denotes absolute temperature. This equation implies that when the area of a surface of separation is increased by 1 cm. 2 at temperature T, the external agencies do work amounting to γ ergs against the surface-tension: and this energy, together with a further contribution of —T d γ/ d T ergs which is appropriated from the heat-energy of neighbouring bodies, becomes resident in the film, giving rise to an increase of λ ergs in its internal energy.

scholarly journals The surface-tension theory of muscular contraction

1925 ◽  
Vol 98 (692) ◽  
pp. 506-515 ◽  
Keyword(s):  
Surface Tension ◽  
Lactic Acid ◽  
Total Energy ◽  
Mechanical Response ◽  
Mechanical Energy ◽  
Chemical Change ◽  
Muscular Contraction ◽  
Muscle Twitch ◽  
Constant State ◽  
Higher Temperature

It was shown by Bernstein (1) in 1908 that the maximum mechanical response in a muscle twitch is greater at a lower temperature. Since surface tension decreases as the temperature is raised, this observation was regarded as strong evidence in favour of the theory that “ changes in surface tension are a controlling factor in the development of the energy of muscular contraction ” (Bayliss (2), p. 448); other physical effects such as osmotic pressure and “ Quellung ” were, according to Bernstein, excluded since these increase as the temperature is raised. If it had been shown at the same time that the total energy liberated in a muscular contraction was independent of temperature, the mechanical energy alone varying, this might indeed have been regarded as in favour of a surface-tension theory. Actually, however, the total heat set free in a twitch decreases as the temperature is raised, in just the same way as does the tension; indeed, there is a very constant relation between the two, so that for a given liberation of total energy , i. e., for a given chemical change , the tension energy set free is independent of the temperature . Bernstein’s observation, therefore, gives us no grounds for concluding that the development of the mechanical response in muscle is due in any way to changes of surface tension. To put the matter in terms of lactic acid, a given production of lactic acid is accompanied by the same rise of tension whatever the temperature. If further evidence be required against the deduction from Bernstein’s observations it is supplied by the fact that in a tetanic contraction the tension developed and the heat set free are both greater, and not less, at the higher temperature. When a frog’s muscle is maintained in a constant state of contraction by a succession of stimuli, the tension is not lower at a higher temperature, as it should be on the surface-tension theory, but appreciably higher. Another explanation of these facts has been given by Hartree and Hill (3, p. 141).

METHOD OF DETERMINING THE SURFACE TENSION AND SURFACE ENERGY OF TRIBOLOGICAL WEAR PARTICLES

Tribologia ◽  
2021 ◽  
Vol 293 (5) ◽  
pp. 61-71
Author(s):  
Jan Sadowski
Keyword(s):  
Surface Tension ◽  
Surface Energy ◽  
Experimental Testing ◽  
Mechanical Energy ◽  
Wear Particle ◽  
Specific Enthalpy ◽  
Wear Particles ◽  
Wear Product ◽  
Wear Products ◽  
Definition Of

Surface tension of friction wear product material is linked with unit mechanical work of newly-formed surfaces of solids. A definition of surface energy also addresses the thermal effect, which is indirectly connected with wear. Physical differences between the development of liquids and solids surfaces are discussed. Both of the quantities defined are described in analytical terms and their value is determined for a selected example of experimental testing. The discussion is based on the first law of thermodynamics using the concept of specific enthalpy of wear products. Boundaries of an area in space where mechanical energy is dissipated and dimensions of a wear particle being formed are taken into account. Mechanical and thermal parts of the energy balance are differentiated.

The nucleation of cavities at grain boundaries

1987 ◽  
Vol 45 ◽  
pp. 288-291
Author(s):  
P. J. Goodhew
Keyword(s):  
Surface Tension ◽  
Surface Energy ◽  
Grain Boundaries ◽  
Radiation Damage ◽  
Impurity Concentration ◽  
Driving Force ◽  
Nucleation And Growth ◽  
Phase Boundaries ◽  
Cavity Nucleation ◽  
Spherical Bubble

Cavity nucleation and growth at grain and phase boundaries is of concern because it can lead to failure during creep and can lead to embrittlement as a result of radiation damage. Two major types of cavity are usually distinguished: The term bubble is applied to a cavity which contains gas at a pressure which is at least sufficient to support the surface tension (2g/r for a spherical bubble of radius r and surface energy g). The term void is generally applied to any cavity which contains less gas than this, but is not necessarily empty of gas. A void would therefore tend to shrink in the absence of any imposed driving force for growth, whereas a bubble would be stable or would tend to grow. It is widely considered that cavity nucleation always requires the presence of one or more gas atoms. However since it is extremely difficult to prepare experimental materials with a gas impurity concentration lower than their eventual cavity concentration there is little to be gained by debating this point.

A new method for quantifying the blocking of coated paperboard

TAPPI Journal ◽  
2010 ◽  
Vol 9 (5) ◽  
pp. 29-35 ◽  
Author(s):  
PAULINE SKILLINGTON ◽  
YOLANDE R. SCHOEMAN ◽  
VALESKA CLOETE ◽  
PATRICE C. HARTMANN
Keyword(s):  
Surface Roughness ◽  
Fatty Acid ◽  
Surface Energy ◽  
Film Thickness ◽  
External Factors ◽  
Additive Concentration ◽  
Pressure Surface ◽  
Fatty Acid Amides ◽  
Coated Surfaces ◽  
Definite Period

Blocking is undesired adhesion between two surfaces when subjected to pressure and temperature constraints. Blocking between two coated paperboards in contact with each other may be caused by inter-diffusion, adsorption, or electrostatic forces occurring between the respective coating surfaces. These interactions are influenced by factors such as the temperature, pressure, surface roughness, and surface energy. Blocking potentially can be reduced by adjusting these factors, or by using antiblocking additives such as talc, amorphous silica, fatty acid amides, or polymeric waxes. We developed a method of quantifying blocking using a rheometer. Coated surfaces were put in contact with each other with controlled pressure and temperature for a definite period. We then measured the work necessary to pull the two surfaces apart. This was a reproducible way to accurately quantify blocking. The method was applied to determine the effect external factors have on the blocking tendency of coated paperboards, i.e., antiblocking additive concentration, film thickness, temperature, and humidity.

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