2. A sticking together, as of substances or tissues; sticking something to something else: Glue and paste provide the means of adhesion as well as adhesive tape.
3. The grip of a wheel on a track, etc.which is produced by friction, or the friction itself: It was difficult to convince the elderly to write e-mails with the computer considering their adhesion to using a pencil or pen and paper for written communication.
4. The attachment to someone or an organization by remaining with it as a partizan, a supporter, or a follower: Patricia was honored for her adhesion as a worker for homeless people for so many years.
5. A mass of fibrous connective tissue in the body that joins two surfaces that are normally separate: Adhesions are usually scar tissues that have formed after an inflammation of some part of the anatomy or the natural healing process that takes place after surgery.
Some abdominal adhesions bind loops of obstructions together and so they usually require the surgical cutting of the fibrous tissue in order to free them of the blockages.
Synthetic nanoadhesive mimics sticking powers of gecko and mussel
Geckos are remarkable for their ability to scurry up vertical surfaces and even move along upside down.
Their feet adhere temporarily, coming off of surfaces again and again like a sticky note; but put those feet underwater, and their ability to stick is dramatically reduced.
Water is an enemy of adhesives, which typically do not work well in wet environments; think of how long a bandage on your finger lasts. Now two Northwestern University biomedical engineers have successfully married the gecko’s adhesive ability with that of an animal well known for its sticking power underwater: the mussel.
Combining the important elements of gecko and mussel adhesion, the new adhesive material, called “geckel”, functions like a sticky note and exhibits strong yet reversible adhesion in both air and water.
“I envision that adhesive tapes made out of geckel could be used to replace sutures for wound closures and may also be useful as a water-resistant adhesive for bandages and drug-delivery patches.
Such a bandage would remain firmly attached to the skin during bathing but would permit easy removal upon healing,” said Phillip B. Messersmith, professor of biomedical engineering at Northwestern’s McCormick School of Engineering and Applied Science.
A gecko’s strong but temporary adhesion comes from a mechanical principle known as contact splitting.
Each gecko foot has a flat pad that is densely packed with very fine hairs that are split at the ends, resulting in a greater number of contact points than if the hairs were not split. In fact, the diameter of one of the split hairs is as small as 200 nanometers.
More contact points between hairs and surface result in a significant increase in the strength of adhesion. Flies, bees and other insects also use this strategy.