Five wonder materials that could change the world
Category Archive: Miscellaneous
Permanent link to this article: http://www.animatedscience.co.uk/2014/five-wonder-materials-that-could-change-the-world
Mar 16 2014
Rough diamond hints at vast quantities of water inside Earth
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Mar 16 2014
Gravitational waves: have US scientists heard echoes of the big bang?
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Feb 22 2014
Vector boson fusion? | Jon Butterworth | Life & Physics
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Feb 21 2014
Men’s Health: Could Pizza Prevent the Stomach Bug? http://google.com/newsstand/s/CBIwx6DU4xE
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Feb 20 2014
The science and magic of pastry | Andy Connelly
The science and magic of pastry | Andy Connelly
Varying amounts of fat, flour and water in the recipe give the full spectrum of pastry, from delicate tenderness to brittle flakiness
The ‘shortness’ or crumbliness of pastry is determined by the extent to which gluten molecules are allowed to form in the dough. Photograph: Dan Lepard/Guardian
Thu 20 February 2014
If you wish to make an apple pie from scratch, you must first invent the universe. Carl Sagan
Most pies offer a degree of mystery: a top crust that fuels anticipation and hides the wonders to come. They allow the chef a “reveal” moment, when the blackbirds come flying out. Jam tarts – the recipe below – may lack this element of surprise, but they excel in terms of simplicity. No custards, crumbles, or curds are required. No complex parcel folding, edge-crimping, or pretensions. Just lovely acid-sweet jam and an explosion of buttery pastry.
Pies and tarts have always been chameleon-like: sweet or savoury, hot or cold, sophisticated or humble. The common factor is always the pastry, the nest in which the myriad treats can be stored. Unfortunately, its exact history is difficult to pin down, pastry having been the forgotten essential in many old cookery books.
The main use of pastry in the ancient world seems to have been to cover meats and fowls during baking to keep in the juices, steam the contents and act as a barrier against contamination. This tradition was carried on in medieval northern Europe where they had the advantage of solid fats, as opposed to oils, allowing for more substantial pastries. They made stiff pastry “coffyns” that could act as containers for stews in the oven, and then be carried to the dinner table. This pastry pyrex was not intended to be eaten by people; well, not rich people anyway.
The three primary ingredients of pastry are fat, flour and water. The ratio and handling of these ingredients give us the full spectrum of pastry, from delicate tenderness to brittle flakiness. Traditionally, the jam tart has been made with shortcrust pastry – “short” because it comes apart into small, “short” irregular particles. However, there is no reason why you cannot make jam tarts from any type of pastry – I’ve tried most of them. The recipe below is for 10 classic shortcrust pastry tarts but it can easily be modified. One common modification is to replace most of the water with an egg to enrich the flavour of a shortcrust pastry and to provide proteins, which help bind it.
200g plain white flour
100g butter (at a cool room temperature)
About 40ml (3 tablespoons) cold water
Jam – of your choice
Cut the fat into small pieces with a knife and mix with the flour. Using your fingers, rub the fat into the flour until the mixture resembles rough bread crumbs. Now sprinkle a little water at a time onto the surface and mix with a knife, then your hands, until a ball of dough forms with the texture of slightly dry playdough.
Keep handling to a minimum as it is not cold hands (or a warm heart) that are key to quality shortcrust pastry, but minimising the formation of the stringy, elastic protein gluten. By rubbing fat into flour before adding any liquid, small cells of flour coated in fat are formed, giving shortcrust pastry its fragmentary, discontinuous, particulate texture. This layer of fat makes it difficult for water to hydrate the flour, so structure-giving gluten proteins cannot form. The more coated the flour cells, therefore, the less well they will bind with their neighbours and the weaker (shorter) the pastry will be. However, if the flour is too well coated the pastry will not hold together and will become difficult to work with. This can happen if you use oil or if the solid fat is too warm.
The type of fat also has a significant impact. For me, flavour is the most important consideration and so I always use melt-in-the-mouth butter. However, it has its disadvantages. Between 15 and 20C butter has a solids content ideal for handling; outside this range it is either too fluid or too hard. This handling range is particularly important for laminated pastries, such as filo, which require layers of solid fat. For shortcrust pastry, a lower solids content is useful as it helps coat the flour. Manufacturers have spent a lot of time and money developing oil-based “shortenings” that have specific textures over large temperature ranges. These can produce great-looking pastry but the higher melting temperatures mean that the fat doesn’t melt in the mouth, resulting in a waxy “mouthfeel”.
Pop in the fridge
Wrap the dough in greaseproof paper or cling film to prevent it becoming dry and the fat absorbing any unwanted flavours from the fridge.
Pastry of all kinds needs to be left to rest in a cool place for at least 15 minutes. This allows the fat to resolidify after handling, making the pastry easier to work with and ensuring that it will hold its shape during the early stages of cooking. Resting also allows two other processes to occur: the diffusion of water through the dough and the relaxation of gluten strands.
When making pastry, flakiness and tenderness are at odds. Tenderness is favoured by conditions that discourage the development of gluten. Since hydration encourages gluten formation we add as little water as possible and then let it diffuse and become well distributed. By contrast, laminated pastries require layers of pastry with sufficient gluten to hold their shape, so a little more water is often required. The ultimate form of this glutinous type of pastry is filo, which in its raw form consists of one thin glutinous layer. Filo pastry contains very little fat itself but relies on fat being added later in between incredibly fine sheets, allowing them to separate during cooking, and so shatter in the mouth into fine delicate shards.
Water content is also affected by the type of fat used. Pure fats such as lard contain virtually no water, whereas butter is about 15% water, and margarine has an even higher water content. For this reason many people mix butter and lard to combine the flavoursome properties of butter and the better texture that lard provides.
Gluten strands will form in your dough while you are working it; they will stretch and twist, giving elasticity to your dough, known as “bounce back”. The more you work with your dough, the more gluten will develop, leading to an elastic dough that will shrink in the oven and lack tenderness. This is why a light touch is so important and why the dough is left to relax in the fridge. Here the strands become more settled in their new form and so the dough becomes easier to shape, roll and fold, and will not shrink in the oven. A little lemon juice can also aid gluten relaxation and help stop discolouration of pastry during handling.
Sprinkle the work surface lightly with flour and rub the rolling pin with flour. Take your pastry out of the fridge and roll it about 2-3mm thick. Roll using even pressure and gentle strokes away from you, giving the pastry a quarter turn after each roll. Occasionally flip it over to ensure that the pastry is not sticking and dust more flour on the surface as needed.
On paper, the main difference between puff and shortcrust pastry appears to be the fat content. Shortcrust will generally have a “half-fat-to-flour” ratio (by weight) and puff pastries roughly equal quantities of flour and fat. However, fat content is only part of the story. The key difference is in the role of the tourier who rolls the dough out on their chilled marble slabs or tours.
For laminated puff and flaky pastries the tourier will fold and roll the pastry over and over onto itself. This develops strong two-dimensional glutinous layers and traps air between them. This air then expands on heating, giving height to your pastry. However, pastry will stick to pastry unless well lubricated with fat rolled or marbled between these layers. In true puff pastry only about an eighth of the fat is mixed into the dough – the rest is rolled into sheets and interlaced with layers of dough. The result of this time-consuming process is hundreds of layers of fat and pastry which grow in the oven, filling with air and steam.
To create our shortcrust jam tarts, cut pastry circles that are a couple of centimetres bigger than the holes in the baking tray. Black metallic muffin or small pie baking trays work well.
Now it is time to add the sweet heart to your jam tart. Place a small spoonful of jam in the centre of each. Be very careful not to add too much jam as it will boil over the sides of the pie and you will never be able to remove the jam tart from the tray! My rule of thumb is to add just a little bit less than you think you need.
Into the oven
The smell of hot jam tarts in a warm kitchen on a cold winter’s day is heaven. Sugar, fat and fruit fight for attention in your nose, feeding your anticipation. As the temperature of the tarts increases a race will start between the sag of melting fat and the drying of the structure-forming gluten network. This makes oven temperature a tricky decision. The hotter the oven, the more rapidly the gluten network will form, but it is also likely that that the filling will boil over. Lower temperatures will help stop boil-over but might mean the fat melts before the gluten network can form, leading to the nightmare of a soggy bottom. A good compromise seems to be 180-200C.
In breads and cakes the gelatinisation of starch helps give shape. In shortcrust pastry, however, starch is generally less important. In hot water pastry the larger amount of water means that a strong gelatinised starch network has already formed before cooking, giving a very strong pastry to work with. In shortcrust pastry there is so little water that the starch can only partially hydrate. However, in absorbing the little water available it helps dry out the gluten network and so set the structure. Any sugar you added to the pastry will also help dry your pastry and help develop colour and flavour through caramelisation reactions.
As higher temperatures are reached water starts to evaporate, forming steam. In laminated pastries this will push the fat-lubricated layers apart. This is where butter is a mixed blessing – it has a higher water content, which generates steam, but does not separate layers as well as pure fats such as lard. Another problem can occur if you have damaged the layers, for example by pricking them with a fork before “blind baking” a pastry case. But this releases hot air and steam and can prevent the separation of the layers.
Towards the end of cooking, when the surface of the pastry has reached a high enough temperature, Maillard browning reactions will start. Brushing the pastry surface with raw egg will add to these reactions and also forms a waterproof layer, which is again useful in blind baking.
After about 15-20 minutes take a look at your tarts. If the browning reactions have taken place and you have beautifully pale brown tarts, take your glistening prizes from the oven and leave them on a wire rack to cool. This allows any residual moisture to escape and gives you time to make a cup of tea with which to enjoy one of your delicate, sweet-hearted pastries.
Permanent link to this article: http://www.animatedscience.co.uk/2014/the-science-and-magic-of-pastry-andy-connelly
Jan 01 2014
A science news preview of 2014 http://www.bbc.co.uk/news/science-environment-25301485
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Dec 23 2013
Students: Christmas revision tips
Students: Christmas revision tips
Eating mince pies and hanging out with your family might sound more fun than revision, but you can fit in both if you plan your time well
Studying for January exams doesn’t have to ruin your Christmas if you’re organised.
The Christmas holidays are upon us; a time for socialising, partying and… revising. Unfortunately. But your festive break need not be a whirlwind of stress, essays and panicking – there’s still time for plenty of merriment along with the stacks of revision. If you’re organised you can still do well in your January exams and have a good Christmas too. Here are some tips to make your life easier this holiday season (warning: will include Christmas puns).
1. Work little and often
One option to tackle the mountain of revision is to set aside a few hours a day, every day. If you’re an early bird then get up in the mornings before the rest of your family are awake and there is still “peace on Earth”. If you work better in the evenings then wait until “not a creature is stirring, not even a mouse” before you hit the books. Getting a little bit done each day means that you’ll still have time to see friends and family throughout the holidays while not overloading yourself with work.
2. Do a marathon revision session
At the other extreme to “little and often” is the “just-sit-down-and-do-it-all-in-one-go” approach. Only the mentally and physically tough can endure this hardcode work-method. Be antisocial and shut yourself away from your family then emerge after three days ready to step into Christmas having done all your work. On the plus side it means that you get all the work out of the way and can enjoy the rest of the break knowing you have nothing hanging over your head.
This could work for essays or coursework, but with revision you’ll need to refresh your memory nearer the exam, so bear this in mind before you get too carried away with the mulled wine.
3. Stay longer at university
If the idea of getting it all done in one go appeals to you then you might have decided to stay behind at uni to work for a few extra days. If it’s too late now, perhaps it’s one to think of for next year: your house will be quiet if all your flatmates have gone home meaning you can really focus with no distractions. It also means you don’t have to lug all your books back with you and you can then head home knowing you’ve got it all done.
4. Prioritise and plan
Find out what events are coming up that you simply must attend; plans your mum has made on your behalf, meet-ups with friends, family dinners and so on. Fill in your diary for the whole holiday so you can see when you realistically have spare time and fit in your work days with your social days to maintain a good work-life balance.
Christmas is a family time so it’s important to prioritise this as well as your work. By mapping out your activities you can see what’s coming up and when you’ll need to have work done by so you can enjoy leisure time with a free conscience. All work and no play is not good, so make sure you do plan some time to “rock around the Christmas tree”.
5. Be organised
You’ll save yourself so much time when it comes to revision if your notes from the term are all filed neatly. You’ll find important information will be more accessible and your references will be at your fingertips. If it takes you two days to scramble your notes into some form of order then that’s two days out of your holiday wasted. If you’re super keen you could make a revision timetable.
6. Waste not, want not
There’s nothing worse than lying around doing nothing, then the next day realising you have two days’ work to do in one day. Your time needs to be managed effectively to make sure none of it goes to waste. This doesn’t mean you have to work 24/7 but perhaps lying in your pyjamas eating a whole tin of Quality Street isn’t the best way to spend every day of your holiday.
7. Keep your brain active
There’s no point spending hours staring at textbooks, a computer screen or lecture notes if it’s just not going in. Your brain can only focus on one thing for about an hour at a time, so half a day on one activity will not be the most effective method to revise. You’ll get much more out of your work session if you swap tasks. If you are revising one topic try doing different activities on it so your brain doesn’t get bored and start to wander off. To help increase concentration span there are some great brain training games and websites. They’re fun but count as work too.
8. Have breaks
Take regular breaks throughout the day to boost your brain power and energy levels. A change of scenery and movement will do you good – even if it’s a five minute chat to your mum in the kitchen or a cuddle with the cat. Allow yourself longer breaks too; take the dog for a walk or indulge in a nice lunch where thinking about work is banned.
Return to the books after half an hour refreshed and ready to go again. You can get a serious case of cabin fever if you don’t take breaks. Stay positive and think about all the things you have to look forward to – it’s the most wonderful time of the year after all.
9. Implement a sophisticated reward system
If you have to revise, make sure to give yourself rewards. Photograph: Alamy
Have a checklist of things you want to complete by the end of each revision session, and each time you tick one off reward yourself. Whether it’s with a five minute break, a cup of tea or a mince pie or three, having an incentive to finish will keep you going. A word of warning – consistent rewards with baked goods will lead to weight gain – maybe limit yourself to five boxes of mince pies, four yule logs and just the one Christmas pudding?
10. Make it a family affair
There’s no rule that says revision and work need to be solo activities. Fair enough if you work better alone, but sometimes it’s helpful to ask for others’ help. They could test you with note cards, proofread or just provide constant cups of tea. If this doesn’t sound ideal but you can work with noise then take your laptop into where they are to have some company. There’s no need to be “lonely this Christmas”.
So, you can spend time with family, friends and your textbooks this Christmas. That’s that sorted, now back to the last minute Christmas shopping.
Permanent link to this article: http://www.animatedscience.co.uk/2013/students-christmas-revision-tips
Dec 17 2013
We’ve reached the end of the world: Antarctica | Alok Jha
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Dec 03 2013
Don’t let dubious Pisa league tables dictate how we educate our children | Peter Wilby
The triennial results from the Programme for International Assessment (Pisa), due on Tuesday but trailed in the Sunday press, have become education’s equivalent of the football World Cup. And the performance of the British teams is just as mediocre, giving more leverage to politicians determined to get a few easy cheers from slagging off teachers.
In the 2009 tests the UK was around average, with England, Scotland and Northern Ireland roughly on a par, and Wales doing even worse. The English and Scots did better than Peruvians, as you’d expect, but they were not up there with the Chinese, Singaporeans, Koreans, Japanese or Estonians and Poles. Little change this time, apparently. So much for Tony Blair’s “education, education, education”, for it was under his regime that the 15-year-olds who took the latest tests in maths, science and reading in 2012 got most of their schooling. Michael Gove will take that as vindication of his policies, which involve transforming everything from curriculum to ownership of schools.
The judgments of Pisa, which tests more than 500,000 pupils in 66 countries – and also looks at factors that might influence the scores such as education spending and school autonomy – are treated as authoritative and unquestionable. One of the few areas where UK children are above average is in being happy at school. Those world-class Koreans are bottom of that league table, and the Estonians and the Poles aren’t far above. Gove will probably announce a national drive to raise misery standards in schools.
As they say in sport, you can’t argue with the scoreboard. But in Pisa’s case, we can and should. There are ample reasons not only to question whether average scores from written tests can adequately assess the quality of school systems across the planet, but also to argue that international testing regimes pose a threat to national sovereignty and cultural diversity.
For an international test to work, all students have to answer the same questions, or at least questions of similar difficulty. In one obvious sense, they don’t: the questions are translated into different languages which, according to one Norwegian academic, “results in rather strange prose” in his country. Besides, “literacy” in Finnish or Korean, where words are consistently written as they are spoken, is different when compared with literacy in English.
Danish academics, when they analysed the 2006 Pisa tests, found that eight of the 28 reading questions were deleted from the final analysis in some countries. Moreover, about half the students participating that year weren’t tested on reading at all. The OECD, which runs Pisa, says it calculates “plausible values” for the missing scores, and this is a standard statistical device. But it’s a hard idea for most of us to get our heads round, and many statisticians dispute its validity, suggesting that the results are nonsensical and meaningless.
Problems also arise from different cultures, and different attitudes to education in general and tests in particular. For example, French students won’t guess the answers to multiple-choice questions; they decline to answer, though a guess gives at least a 25% chance of being right. East Asian countries always do well; critics argue that’s not because their schools are brilliant but because of deference to authority and an anxiety for success that leads parents to seek intensive out-of-school tutoring. There’s scope for gaming, even cheating, since the tests are supervised by research institutes in each country. Some countries are suspected of excluding their weaker performers.
To be fair, the OECD reports contain numerous caveats and warn of margins of error in their league tables. But that won’t stop education ministers such as Gove and his opponents such as Labour’s Tristram Hunt from mining the data to make political capital. Disgracefully, Gove used the 2009 results to claim that English schools had gone “down, down, down” since 2000, when test results were better and 15-year-olds had mostly been educated under the Tories. He ignored clear warnings from the OECD that the 2000 results were flawed and shouldn’t be used for comparisons.
Indeed, the Pisa results provide little support for Gove’s ideas, and still less for Boris Johnson’s. Finland, the most consistent high performer, has the least selective, most comprehensive system in the world, and it has no inspectors, no exams before 18 and a national curriculum that is confined to broad outlines. Sweden really has gone “down, down, down” since it introduced the free schools that Gove has imitated. The US, with its charter schools also a model for Gove’s free schools, does no better and, in mathematics, it does much worse than England.
But we should be wary of cherry-picking the results or, for that matter, paying any heed to them at all. Andreas Schleicher, the OECD man in charge of Pisa and once described by Gove as “the most important man in English education”, wrote last year that “deficiencies” in UK education would lead to £4.5 trillion in lost economic output over a lifetime. To which we should respond: how does he know and what does it matter anyway? Behind the Pisa tests lies an ideology that accepts economic growth and competitiveness as the sole aims of schooling. The definition of educational success is being standardised and it is being narrowed.
For fear of falling behind we must all adopt “best practice” as revealed by the OECD. By focusing on economic imperatives, schools risk losing sight of their roles in nurturing social solidarity, passing on cultural heritage and promoting civic engagement. Might justice, social harmony and a clean environment be just as important for our children’s future as economic prosperity?
By all means, learn from what others are doing in their own schools. But don’t allow league tables of dubious provenance to dictate how we decide to educate our children.
Permanent link to this article: http://www.animatedscience.co.uk/2013/dont-let-dubious-pisa-league-tables-dictate-how-we-educate-our-children-peter-wilby
Nov 06 2013
Warming gases reach record high http://www.bbc.co.uk/news/science-environment-24833148
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Oct 20 2013
Queensland solarium ban will save lives, Cancer Council says
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