Why do washing powders remove stains but not dyes?

Why do washing powders remove stains but not dyes?

one of the main and important ingredients used is surfactants and the surfactant molecule is clever in the way that on one side it has a hydrophobic component, that’s a water-hating molecular chain. And on the other side, a hydrophilic water-loving component. The hydrophobic chain finds itself sticking to the stains on your clothes and the hydrophilic heads have a stronger attraction to water. They’re able to surround the dirts and roll it up into a small globular-type ball and the end result is that they’re able to lift the stain from your cloth, into the wash water.

Some of our detergents contain enzymes which are naturally derived molecules. Generally, we use different enzymes such proteases which break down proteins and amylase which breaks down starch and then finally, another major ingredient that we use, like most other detergent manufacturers is bleach. The bleach turns the stain into more soluble colourless particles that can be easily removed and carried away into the wash water. So, in actual fact, it can remove bleachable dye stains. So, to kind of answer the other part of the question, laundry detergents can remove certain dyes, as well as stains.

Most dyes are composed of molecules that these ingredients can’t target. Surfactants can't globuralize the dyes, nor can enzymes gobble them up, unless they're vegetable-based. But bleach can effect dyes and this is why, washing powders designed for colored clothes don’t contain any bleach.

Why is flu more prevalent in winter?

Why is flu more prevalent in winter?

we think flu spreads better in winter because of human behaviour because it does this reproducibly in every country in the world and in which it is winter time - it doesn’t mean it goes away completely in summer but it does come much more commonly in winter.

We think that’s because it spreads better in winter because of what humans do. We go indoors more in winter so there are more people together indoors with the windows closed. Also, unlike summer time, it’s less light and therefore there's less ultraviolet radiation to dry out the virus and kill it. So 'flu finds it easier to persist on surfaces spread by coughs and sneezes, and it hangs around for longer.

As a result you have a higher chance of passing it on so that’s what we think goes on. And then the big determinant, the disproportionate determinant, is the school year. The long summer school holiday powerfully knocks 'flu on the head because kids stop mixing and spreading the infection amongst themselves. What normally happens is that they become infected and then go home and give it to their parents and the parents then carry the infection to all of the other parts of the social and age strata, usually through their workplace.

why don't woodpeckers get brain damage when they hammer into a tree?

why don't woodpeckers get brain damage when they hammer into a tree?

In the late 1970s scientists tackled this by using a very fast camera capable of taking 2000 pictures every second. Analysis of these images showed that a woodpecker's head tolerates a force of about 12 thousand times the force of gravity whenever it hits something, which is a considerable force going through its head, so why shouldn't it get brain damage? Well there are various woodpecker adaptations which means they are able to cope with this trauma, and one of them is that their skull bones are quite spongy which mean they can absorb shocks very well. Another adaptation is that a woodpecker's brain is small and so has a very big surface area to weight ratio, and so the force is spread over a large area. The photography also revealed that woodpeckers line their heads up very straight with whatever they tap into, so there's no rotational injury which, at least in people involved in car accidents, is a major cause of brain injury as delicate nerve fibres are torn by the brain trying to twist on itself.

How do whales hunt and eat prey without swallowing gallons of water?

How do whales hunt and eat prey without swallowing gallons of water?

They filter the water. If you've ever seen a baleen whale, they have a big floppy sack under their jaw, called a baleen, which works like a giant tea strainer. The whale takes a mouthful of water and then squirts it out again through the baleen, trapping all the plankton they want to eat in there so they swallow just plankton and not mouthfuls of water.

Can lightning re-start your heart?

As lightning can strike in the same place twice if you get struck by lightning and it stops your heart and then you get struck by it again would it restart you heart?

Firstly the short answer is yes, it is possible that being struck twice by lightning would firstly stop your heart and then restart your heart. The answer is a bit more complicated than that though. The heart cells maintain a voltage drop across them which controls the inflow and outflow of ions. These ions allow the heart to beat. If the heart’s struck by lightning that voltage drop is immediate and the heart will contract. Unfortunately if the lightning strikes the heart at the wrong part of its relaxation the cells will not contract together, rather chaotically. The heart will enter a rhythm called fibrillation. This doesn’t allow it to pump. For that reason the pulse would stop and the heart would be said to be arrested.

If a second strike of lightning or an electric shock occurred at the same point when a heart was fibrillating it would be possible that the heart cells would all contract together in a more ordered fashion. However, there is a problem. The heart could also be struck by lightning and instead of going into this fibrillating chaotic rhythm it could go into no rhythm at all. It could quite simply not beat again. That’s called asystole. It doesn’t end there unfortunately, our poor unfortunate victim also suffers elsewhere. It’s likely that the chest would become relatively stiff and the chest muscles would go into spasm. These muscles take a lot longer to recover than heart muscles so it would be very unlikely that your victim would be able to breathe again. For that reason, although the heart may well restart the victim may well die.

Why do some people blink more than others?

Why do some people blink more than others?

Most people blink once every two-to-ten seconds. Blinking can be triggered by dust or pollen, if you get hay fever in the summer like I do. It’s mainly controlled by nervous impulses from the brain. Everyone has a sort of blinking pacemaker in their brain and everyone’s is different. Everyone’s is set slightly differently.



This area of the brain is known as the chordate nucleus and it controls your blinking by sending impulses down the nervous system into the muscles around your eyelids. There are of course other things that can affect your blinking like fatigue and also some diseases like Parkinson’s and nerve disorders.



What’s quite interesting is that when we blink we don’t actually notice that we’re blinking because our brains filter out the signal. It’s the same as when you move your eyes around a room. Your brain cuts out the signal of when your eyes are moving so that you don’t get confused and feel like the world is spinning. It’s called corollary discharge.

If a mosquito bites someone with HIV and then goes and bites someone else will it pass on the disease?

If a mosquito bites someone with HIV and then goes and bites someone else will it pass on the disease?

Thankfully, no. Because otherwise Africa would have a much worse problem than it currently has where there are something like 4 million new cases of HIV every year. They’re thankfully not caused by mosquitoes. If they were we would all be in really serious trouble because it would be like malaria. The reason is really simple because we know that mosquitoes are very good at transmitting viruses, certainly things like dengue gets spread by mosquitoes and that’s a virus.

There’s a very good reason why this isn’t the case with HIV which is that HIV is a very specialist virus which has on its surface viral velcro, molecular docking stations that lock on to certain parts of cells, CD4+ cells which you only find in us, in humans. There’s related versions of HIV in chimpanzees (SIV) and they have their own specific cells that it locks onto. Because those specialist cells are only found in us HIV is a very fragile virus. It can’t survive in the mosquito’s intestine, it can’t latch onto cells in the mosquito, therefore the mosquito doesn’t get infected. Therefore the mosquito can’t amplify the dose from the person it bites. Therefore it can’t infect the next person because it can’t inject more viruses than it took in. HIV is very poor at infectivity. It’s actually very hard to catch, believe it or not. You can reassure everyone you’re not going to catch HIV from a bite.

How is oxygen made and recycled on the International Space Station?

How is oxygen made and recycled on the International Space Station?

The oxygen isn’t strictly recycled. The carbon dioxide that the humans breathe out is filtered out of the air with a molecular sieve then simply dumped overboard. The oxygen is created from the water that comes from the air and from the washbasins and from the loos. After that water is cleaned up it is electrolysed. An electric current is passed through it and it is separated into hydrogen and oxygen. The hydrogen is dumped overboard; the oxygen is fed into the cabin for the crew to breathe.

What happens in scientific terms in a reaction between acid rain and limestone?

What happens in scientific terms in a reaction between acid rain and limestone?

Limestone is mostly made up of the mineral calcium carbonate ( CaCO 3 ) this is not very soluble so the rocks don't dissolve very quickly. If you add an acid however you add Hydrogen Ions ( H+ ) which will react with the carbonate to form hydrogen carbonate HCO3- ions which are very soluble in water, and the limestone will dissolve. Or if there is more acid about the two Hydrogen ions will react with a carbonate to form H2CO3 which will decompose to form carbon dioxide CO2 and water H2O.

The acid can come from a variety of sources sulphur and nitrogen oxides released by burning fuels will form sulphuric and nitric acids, can carbon-dioxide can dissolve in water to form carbonic acid.

If your hair is red why does it go white? Does it change structure?

If your hair is red why does it go white? Does it change structure?

The process is very likely to be the same as any other hair colour. All you’re doing is losing from the hair the ability to add some colour. The colour is accounted for by different forms of melanin: the same hormone, the same chemical in the skin that makes you go brown. You just lose the ability to add that to the hair so you see the natural colour of the hair: the keratin and that’s the stuff which is white.