Friction
Paul Grimshaw, Michael Cole, Adrian Burden, Neil Fowler in Instant Notes in Sport and Exercise Biomechanics, 2019
Heat is often generated at sites of friction between two objects in contact. Within the human body this heat can cause damage to the soft tissue structures. Blisters would be an example of excessive amounts of friction between two surfaces in contact in the human body. The body would respond by producing a layer of fluid between the superficial and deep layers of skin, thus trying to protect the deeper layers. In the long term, the superficial layer of skin often becomes thickened, as in the case of the skin on the ball of the foot. Lubrication of the surfaces in contact helps reduce the amount of friction between objects in the dry condition. Articulating joints within the body that are lubricated with synovial fluid can produce a sliding system that is five times as slippery as ice on ice. As a result human joints can last for well in excess of 70 years before significant wear and tear issues occur (such as arthritis and joint degeneration).
Role of Surfactant in Other Organs
Jacques R. Bourbon in Pulmonary Surfactant: Biochemical, Functional, Regulatory, and Clinical Concepts, 2019
There are basically two types of lubrication, the first occurring where there is solid-to-solid contact (boundary lubrication), while the second arises where the two sliding surfaces are separated by a fluid film or wedge of liquid which keeps them from touching. Needless to say, this liquid wedge will only bear an appreciable load if there is rapid motion to develop a planing action (hydrodynamic lubrication) or fluid is actively pumped into the gap between the surfaces (hydrostatic lubrication). Fluid-film lubrication75 reaches much lower coefficients of friction, typically of the order of 0.01 to 0.001, but requires velocities roughly an order of magnitude higher than typical joint sliding rates in order to maintain separation of the surfaces. Below this velocity, which is dependent upon lubricant viscosity, the surfaces touch and boundary lubrication is all that remains to facilitate motion.
Petrolatum: Conditioning Through Occlusion
Randy Schueller, Perry Romanowski in Conditioning Agents for Hair and Skin, 2020
Its lubrication properties are useful in the automotive industry, especially during reassembly of transmission parts. In the candle industry, petrolatum is used as a lubricant and also for aiding in the dissolution of fragrances, as well as for minimizing wax shrinkage when clear jar candles are cooled. Petrolatum's characteristics enable it to be used in textile manufacture, where it is employed as a thread lubricant and in fiber finishes. Electrical applications benefit from petrolatum, where it is used as a lubricant, insulation, and rust preventative in electrical junction boxes. Petrolatum also can be used as a food-grade grease, as a rust preventative in food processing, and as a food release agent. Its use in industrial applications is primarily in applications where a remaining tacky film is desirable, such as in penetrating oils and in gasket lubricants and seals. Petrolatum's lubrication properties and its waterproofing abilities also are useful in the manufacture of munitions.
An overview of thermal necrosis: present and future
Published in Current Medical Research and Opinion, 2019
Mohamed Mediouni, Theodore Kucklick, Sébastien Poncet, Riadh Madiouni, Amine Abouaomar, Henning Madry, Magali Cucchiarini, Bohdan Chopko, Neil Vaughan, Manit Arora, Kemal Gökkuş, Mario Lozoya Lara, Lorenlay Paiva Cedeño, Alexander Volosnikov, Mohamed Hesmati, Kevin Ho
During drilling two methods, internal and external cooling, are used for the supply of coolant. Internal irrigation involves feeding of the coolant to the drill tip through tubules in the drill shaft. In closed type internal irrigation, the coolant moves through tunnels inside the drill and back to the central heat exchanger. In open type internal irrigation, the coolant flows through tunnels in the drill and exits from an opening at the drill tip52. External cooling involves feeding the coolant to the surface of the drill at the entry point. In order to reduce friction during drilling, lubrication has been used. Matthews and Hirsch36 proved that cooling is highly effective in limiting maximum temperature elevations. Kalidindi35 found that external cooling reduces the temperature generated during drilling.
Critical analysis of in vitro stability testing of spinal implants and proposal for standardization
Published in Expert Review of Medical Devices, 2022
Zoltán Csernátony, Sándor Manó, Zsolt Tiba, Géza Husi, Zoltán Jónás, Tímea Váradi, Loránd Csámer, Ágnes Éva Kovács
Lubrication is one of the key aspects of tribology. A lubricant is usually used to keep a distance between two solid materials, consequently preventing direct mechanical contact with each other. The lower the lubricity, the greater the wear of the examined material. The lubricity of a substance cannot be measured directly, moreover it is significantly influenced by other factors such as the shape, microgeometry and extent of the surfaces, viscosity and density of the lubricant, and temperature and pressure [5]. Lubricants can play a key role in the instability of assembled spinal implants in human bodies. Posterior spinal implants are composed of different pedicle screws and hooks, which are connected to two longitudinal rods. Spinal implants mounted on rods are subjected to significant strain after the correction of deformities, and this is compensated by the clamping force of the set screws securing the implant parts together. In the surgical field, both the loosening of the securing set screws and the sliding of the implants on the rods are facilitated by the undesired lubricity of the environment [6] and can be associated with implant failures due to set-screw loosening [7].
Effect of gap outside contact area on lubrication of metal-on-Metal total hip replacement
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2020
Ali A. Al-Saffar, Sam L. Evans
The main parameter characteristics required to produce an artificial hip joint that is a good alternative to the natural hip joint are to reduce the wear rate to be as small as possible and to improve the lubrication process to develop full fluid film lubrication and avoid asperity contact. Over 70,000 hip replacement joints are performed annually in patients in the United Kingdom (Arden et al. 2011) and more than one million are carried out worldwide every year (Pivec et al. 2012). Metal-on-metal (MOM) bearings could emerge as a good choice for replacing the diseased or damaged natural hip joint, particularly in younger patients. They present a different design challenge and a means to conduct a detailed analysis of the lubrication mechanism taking into account the true shape of the components is a necessary step in building a comprehensive understanding of their operation. They are known to generate large numbers of very small wear particles. There have been examples that have functioned extremely well in patients and others where their performance was less satisfactory. Both of these considerations need a robust accurate lubrication analysis as a basis for further investigation. This is therefore the main focus of the research reported here.
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