Seafood with a dif­fer­ence

Argyllshire Advertiser - - YOUR VIEWS - DOROTHY H CRAW­FORD

There’s noth­ing more de­li­cious than a steam­ing plate of mus­sels, par­tic­u­larly if it is ac­com­pa­nied by a bowl of fries. And liv­ing in Ar­gyll there are plenty of mus­sels. But there is more to these hum­ble bi­valves than meets the eye.

Mus­sels live in colonies on rocks in in­ter­tidal zones, and any­one who has ever tried to col­lect them will know that they are stuck fast and are quite dif­fi­cult to prize off. This is be­cause mus­sels firmly an­chor them­selves to the rough, wet rock sur­faces.

The threads that se­cure them are called byssal threads, which pre­vent them from be­ing swept away by buf­fet­ing tides and waves. These threads form the beard of the mus­sel that needs to be re­moved be­fore cook­ing.

The outer layer of a byssal thread con­tains iron and a sub­stance called cat­e­chol, which bond to­gether to give the threads a unique set of prop­er­ties – they are tough, they can stretch with­out break­ing and can re­con­fig­ure the molec­u­lar bonds when bro­ken.

In­spired by the prop­er­ties of byssal threads, sci­en­tists have now come up with a new plas­tic ma­te­rial that com­bines strength, elas­tic­ity and tough­ness. Its key com­po­nent is the iron-cat­e­chol bond, called a ‘sac­ri­fi­cial bond’ be­cause it breaks when force­fully hit or stretched, and in do­ing so it dis­si­pates en­ergy and al­lows the whole struc­ture to stay in­tact. Once the stress is passed the bonds can re­form mak­ing the ma­te­rial re­us­able.

The ad­di­tion of iron-cat­e­chol bonds makes the re­sult­ing plas­tic stiffer, stronger and tougher than iron-free plas­tics, be­ing over 700 times as stretchy and al­most 60 times as strong. Sci­en­tists pre­dict many uses for this new ma­te­rial in­clud­ing lift­ing, pack­ing and an­chor­ing heavy ob­jects, and, more ex­per­i­men­tally, its in­corpo- ra­tion into ro­bot joints and per­haps in the longer term be­ing used to re­pair dam­aged hu­man joints and ten­dons.

51_a48­mus­sels02

Mus­sels from Mur­ray Smoked Prod­ucts in Lochgilp­head.

There is more to these hum­ble bi­valves than meets the eye.

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