This won’t hurt - much!
QUESTION What happened to the ‘gun’ that fired vaccine in a fine mist to penetrate the skin, avoiding the use of a needle?
Such devices are known as jet injectors and were developed under u.S. military contract for mass vaccination of recruits.
Needle-free devices drive liquid through a nozzle, creating a narrow stream under high pressure that penetrates skin to deliver a drug or vaccine.
When he was chief of the Department of Anesthesiology at the u. S. Marine hospital in Staten Island, New York, Dr Robert A. hingson treated a sailor who had accidentally injected diesel oil into his hand, leaving no visible wound. This inspired him to create the first jet injector, the hingson Peace Gun.
In the 1950s, Aaron Ismach at the u.S. Army medical equipment research and development laboratory at Fort Totten, New York, created a multi- dose jet injector. The electrically powered unit could deliver several vaccines at once.
By 1963, Ismach and his team had developed the foot-operated Ped-O- Jet. Both devices were widely used by the u.S. military, enabling medics to inoculate more than 500 men an hour.
Modernised versions included the Vaccijet, Dermojet, Med- E- Jet, hypospray, BIP-4 and MesoFlash.
In 1985, a u.S. hepatitis B outbreak was linked to jet injections at a california clinic. Subsequently, Vietnam veterans claimed they had contracted hepatitis c due to this injection method. One in ten vets has hepatitis c — five times higher than the rate in the general population.
In 1997, the u.S. military stopped using jet injectors. The World health Organisation does not sanction their use for mass immunisation. Single-use jet injectors can be used by diabetics for insulin.
Dr Ian Smith, Cambridge.
QUESTION How is cheese aged for years yet in my fridge it goes mouldy in weeks? What am I doing wrong?
STORING cheese correctly can improve its shelf life considerably, but care must be taken if it is kept in a domestic fridge. cheese is made by coagulating milk with an acid. After it has been pressed to remove water, it is ripened or aged.
Typically, hard cheeses are aged in cellar conditions, with temperatures ranging from 10c to 15c (50f to 59f) and, crucially, in relatively high humidity.
uncut wheels of Gouda, cheddar and Parmigiano-Reggiano can be aged for several years. Once cut, the cheese will immediately react with the atmosphere and begin to degrade.
At home, cheese requires a stable environment, which is why it’s usually stored in the fridge. however, such a cold and dry environment means that, like other foods, it will dry out.
Methods of cheese preservation are often debated, but experts recommend wrapping it in a special paper coated with wax and polyethylene, which forms a barrier that wicks excess moisture away from the cheese while allowing it to breathe.
An alternative is to wrap cheese tightly in parchment paper and then loosely in plastic wrap.
cheese should not be placed in the main part of the fridge, but in a crisper drawer. These maintain more moderate temperatures and protect the humidity cheese needs to breathe. You can add a damp cloth to maintain humidity.
careful storage means hard cheese can last for months. Semi-hard cheeses, such as Gruyere and Gouda, and blue cheese such as Stilton can last for a fortnight.
Never wrap different cheeses together; their flavours will mingle, so ruining their taste.
cottage cheese and cream cheese should be kept in their packaging. Soft cheese should be discarded if there is any sign of mould growth, as this will have penetrated the entire cheese — unlike hard cheeses, where mould can often be safely pared away.
hard cheese freezes well, which is a good solution if you have any left-over christmas Stilton.
Mary-Louise Franklin, Warwick.
QUESTION How do they get super glue into the tubes without everything sticking together?
SUPER glue or cyanoacrylate adhesive (CA) is a high-strength, instant adhesive that bonds to almost any material.
A small amount of moisture is required to set or cure it. When cyanoacrylate molecules come into contact with water, they begin forming a powerful plastic mesh.
To manufacture CA, ethyl cyanoacetate is placed in a special industrial kettle with revolving blades and mixed with formaldehyde. The mixing produces water, which is evaporated as the kettle is heated.
Because the CA will begin to cure on contact with moisture, the evaporation is constantly replaced with a non-reactive gas, such as nitrogen.
The substance left in the kettle is CA polymer. The kettle is heated again, causing thermal cracking of the polymer and creating reactive monomers that separate out.
At this stage, manufacturers can add additives depending on the end use.
Industrially produced CA is stored in airtight and moisture-free drums or plastic barrels.
The CA can be added to containers using conventional, albeit humidity-free, techniques. These are simply industrial conveyer-belt machines that pump the glue from the barrels into plastic tubes.
Once a tube is filled, a top is fitted and crimped on, and the bottom of the tube is crimped closed.
Because metal tubes, other than aluminium, would react with the glue, the tubes are usually a plastic such as polyethylene.
Once the CA is exposed to moisture in the air or on the surfaces being glued, the monomers will re-polymerise and harden, forming a tremendously strong bond.
L. L. Duffy, Milford Haven, Pembs. IS THERE a question to which you want to know the answer? Or do you know the answer to a question here? Write to: Charles Legge, Answers To Correspondents, Daily Mail, 2 Derry Street, London W8 5TT; or email charles.legge@dailymail.co.uk. A selection is published, but we’re unable to enter into individual correspondence.
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