Tuesday, 16 August 2016

OUCH THAT HURTS!

STINGS!!!

As I am writing this blog I am noticing that it is now wasp season!
August seems to be their peak - certainly in my garden.








I live near a marsh and the mosquitoes are like vampires leaving a huge welt and very itchy!
 A day at my favourite beach reveals more and more jellyish on the sand and don't even get me started on the ants!!

Pretty much the only ravenous insect I encourage are the bees and fortunately my garden is full of them. I have finally managed to get enough plants to bring them in.


A day at the beach especially with a picnic can be a science lesson in the local biting and stinging wildlife.
So what is in a sting or bite and are those old wives tales for treatment really true??


Blue bag for a bee and vinegar for a wasp?













Do you really need to pee on a jellyfish sting??

A little bit of science can help you out.

There are so many websites giving advice for "natural" cures for stings and repellents. It is worth a look but in the panic of a painful sting will you remember what to do??

Bee Sting

Common knowledge says that bee venom is acidic so using a bicarbonate of soda paste will neutralise it and help with the pain. The calming effect of bicarbonate is true - it really does reduce itching and is useful for mosquito bites.


It is true that many bees have a sting that is barbed and will lodge in the skin of a mammal or bird pulling the sting from the abdomen of the bee and killing it. So most bees rarely sting unless on purpose. Their sting is used for inter bee battles when the hive is threatened.
Bee stings are amazingly complex with peptides to break down cells which releases histamines and this is where people with allergic reactions have trouble .
For most of us doctors usually recommend ice to reduce inflammation and give a mild anaesthetic effect with an antihistamine cream .

Wasp Sting


The alkaline nature of a wasp sting has led to old wives tales of vinegar or lemon juice to neutralise the sting. As with a bee sting it is unlikely that this will really happen and will probably hurt because one of the things in wasp venom is acetylcholine which stimulates pain receptors - there is even more of this in a hornet sting.

Ant Bite

Wasp and bee venom varies a little from species to species but ants vary markedly. So it can help to know what has bitten you.
Some ants don't bite but spray formic acid and some use their venom to neutralise attacking ants of a different species!

One final thing in all these insects venom is an alarm pheromone so if you have been stung and kill the insect others will know.........



Jelly Fish

There are more and more jellyfish on our beaches and of course abroad. So there you are splashing around and suddenly you feel a stinging hot pain....yes you've brushed up against a jellyfish or tentacle portion in the water.
The harpoon like cells penetrate your skin easily and inject venom which is designed to paralyse and kill fish and depending on the species will raise a painful welt, blister or make you very ill indeed and could kill you.
However before we all race off the beaches - the sting of most jellyfish found around British water is painful but not lethal.
So having seen that episode of Friends you run off to find someone to pee on you? Well no - because pouring fresh water - including urine - onto a jellyfish sting releases even more venom so experts suggest remove all trace of the tentacle and then  rinse in plenty of salty water and very recent research suggest that hot salty water is best.

Mosquitoes


The female causes the problem and she doesn't actually bite you - she uses her proboscis, which is razor sharp, to pierce your skin and drinks some blood which she can use in the production of eggs. As she finishes and flies away she leaves some of her saliva in the wound which can contain diseases - malaria and zika virus being just two.
Your body reacts to the saliva producing histamine - so tissue swelling, itching and redness. People reacts differently some quite violently and an infected bite can need antibiotics but usually antihistamine will work.
If you are into natural remedies lavender oil works too - and scientists have researched that one.

The best remedy is not to get bitten at all so how do you repel them?
Insect repellants usually produce an odour that insects don't like and so they stay away.
There are plenty of insect repellents that you can buy over the counter which work in similar ways DEET being one well known brand. It does have a greasy feel and unpleasant odour so many people turn to "natural" products and at the moment the trend is for lemon eucalyptus oil. Citronella candles and spray can work too


So sadly the old wives tales/home remedy methods usually over simplify the situation and many don't work at all.
Probably your best bet is ice to reduce the pain and antihistamine for the inflammation  for ant, bee and wasp and warm salty water for a jellyfish.

Have fun!!


PS: For those of you wanting a little more serious science facts here are two amazing  Chemical Compound posters from Compound Interest   http://www.compoundchem.com/








Tuesday, 9 August 2016

COOL SHADES

THE SCIENCE BEHIND YOUR FAVOURITE SUNGLASSES

Whether you opt for heart shaped,the John Lennon look or wrap arounds you do need to protect your eyes from the sun.

The eyes are especially susceptible to the sun because of the transparency of the outer tissues. Long-term exposure can speed up ageing of the macula, the most sensitive part of the retina and can also lead to cataracts.

Look for sunglasses that meet the European safety standards. This means they will be of good optical quality with break-resistant lenses, providing high levels of protection against ultraviolet light, while not distorting colours. It's worth buying a pair with a dark tint and with plastic rather than glass lenses, for safety reasons. One of the key functions of sunglasses is to reduce the amount of sunlight entering the eye. Look for a pair offering a light reduction of up to 80%, that is they will allow in only 20% of the sunlight. The size of the lens - the area shielded - affects light admitted.

 Expensive sometimes means better, but not necessarily. What really counts is the degree to which the lenses filter out harmful UV rays. Look for the CE mark, which proves they conform to the European Community Standard. They should also satisfy British Standard BSEN1836, meaning they will provide high levels of protection against damaging ultraviolet light.

 Don't confuse the shade of the lenses with their ability to filter UV rays. Dark sunglasses may still allow UV rays to enter the eye. 
 Polarising lenses will reduce reflective glare from water and land surfaces, making them particularly good at improving vision in bright or hazy driving conditions.

What about if you wear glasses either for reading or everyday?
Photochromic lenses were invented in the USA  back in the 1960s but were very expensive when they first came to Britain and could be very slow to react.
The original lenses that darkened when exposed to UV rays were made from glass and although the technology has improved especially the speeding up of reaction time the science is still basically the same.
Glass photochrome lenses contain silver chloride crystals that when exposed to UV-A light ( 320 - 400nm) actually make dark elemental silver  & when in the shade the silver reverts to an ionic state and the lenses go clear.







Plastic lenses are different because they use photochromic dyes which rearrange in UV to give darker colours. The dyes need to be in specialist plastics and each company has its own proprietary polymer. Some even sandwich the dye between the plastic. It is an area of lucrative research with a huge market.
The next generation of transitional lenses hope to deal with the fact that drivers can't really use them because many car windscreens actually have a UV blocking coating effectively stopping the sunglasses working.

And in the future?.........
The very latest technology announced recently uses an electrochromic polymer changing colour with electricity


Chemical engineer student Chunye Xu and colleagues from Seattle have been working on "smart" sunglasses that can lighten or darken on command.
Using power from a watch battery the polymer can change shade in one second with milliwatts of power when the button on the side arm is pressed.
Electrochromic polymers are not new but this application uses such a small amount of power and is very quick to respond.
As a prototype they are rather heavy but have real possibilities. The team are also working on glasses to correct sight defects.