Science by Email 25 May 2012

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	25 May 2012
News: Carbon's neighbour By Patrick Mahony Another use of boron is in borosilicate glass, often used in laboratory glassware. Carbon is often called the 'element of life'. It can be found in proteins that make up living cells and in sugars and fats that power them. Carbon combines with hydrogen, as well as other elements, to form millions of different compounds with different uses. What about carbon's neighbour? Boron sits next-door, just left of carbon on the periodic table. Given their close proximity, how come carbon seems so important, yet many haven't even heard of boron? Carbon and boron are similar, but not the same. A key difference is that carbon has four 'spare' electrons easily used to form chemical bonds, while boron only has three. Carbon can form many stable compounds, while boron's 'electron deficiency' means many of its compounds react very easily. One of the simplest boron compounds, diborane, is so unstable it spontaneously combusts in air. Boron has potential medical applications. While simple boron and hydrogen compounds are highly unstable, boron is able to form large molecules called clusters that contain many boron atoms. These clusters form highly stable structures that can act as 'cages' for other molecules. Most pharmaceuticals are based on carbon. One problem for these drugs is selectivity – making sure they only affect the target and not healthy cells. In many cases, this isn't a problem, but with diseases such as cancer, doctors only want to kill tumour cells. Many carbon-based drugs aren't very selective. Chemists hope to use boron-based drugs that are more selective to treat a range of diseases, including various cancers, Alzheimer's disease and depression. The boron-based drugs could be used directly, or as a 'cage' to protect and transport another drug. While it might not be as common or as popular as its famous neighbour, it appears there is a place for boron in our medical future. More information Chemicool - boron Boron harnessed to develop new drugs Boron is the new carbon Careers link Royal Australian Chemical Institute – Career profiles
You will need these materials.   Warm the milk and stir in the sugar and the yeast. Leave for 5 minutes until frothy.   Rub the butter in to the flour.   Break off a quarter of the dough. Knead the remaining dough, removing another quarter every 5 minutes.   Place the four balls of dough in bowls lined with spray oil. Cover with cling film, label, and leave in a warm place to rise.   After the dough has risen, roll into balls and bake.   Try this: Stretchy bread Safety: This activity requires a microwave and hot oven. Younger readers should ask an adult for assistance. See the CSIRO Education safety page for more information. You will need Plain flour Salt Butter Milk Dried yeast sachets Sugar Mixing bowls and spoons Measuring cups and spoons Scales Microwave Oven Oven tray Baking paper Marker Wooden board Cling film Spray oil Oven mitts What to do Place 1 cup of milk in a bowl, and warm on a medium-high setting in the microwave for 1 minute. Stir 2 sachets of yeast and 2 teaspoons of sugar into the milk. Set aside for about 5 minutes, until it's frothy. Meanwhile, mix 3 cups of flour with ½ teaspoon of salt. Use the scales to measure 40 grams of butter. Use your fingertips to rub the butter into the flour, until it looks like breadcrumbs. Mix the milk mixture into the flour until it forms dough. Spray 4 smaller bowls with oil. Break off a quarter of the dough and put it into one of the bowls. Cover with cling film and label it 'No kneading'. Sprinkle some flour on the board. Knead the remaining dough on the board for 5 minutes. Break off a similar amount of dough and place in another bowl. Cover with cling film and label it '5 minutes'. Knead the remaining dough for another 5 minutes. Break off another piece of dough, place in a bowl, cover with cling film and label '10 minutes'. Knead the last bit of dough for another 5 minutes. Place it in the final bowl, cover with cling film and label it '15 minutes'. Place all the bowls in a warm area until the dough doubles in size (about 1 hour). Preheat the oven to 200°C. Line an oven tray with baking paper. In each corner, write one of 'No kneading', '5 minutes', '10 minutes' and '15 minutes'. Punch down each portion of dough. Knead each portion of dough for 2 minutes. Break in half and roll into balls. Place on the tray near the appropriate label. Set tray aside for 10 minutes and then bake the rolls for 5 minutes. Turn oven down to 180°C and bake for another 15 to 20 minutes, until the rolls are golden brown. Let the rolls cool and then taste each one. Are they the same? What's happening? Flour contains a range of proteins. In plain flour, two of the proteins are called gliadin and glutelin. Linking these proteins creates gluten. While the development of gluten will happen naturally over time, kneading speeds up this development. As you knead the dough, you will notice that it becomes stretchier. The formation of gluten in the dough makes it more elastic. This stretchiness is important, as it allows the dough to capture the bubbles of gas made by the yeast. This means that the dough rises properly, resulting in light, fluffy bread. Relatively little gluten develops if the bread is not kneaded. The carbon dioxide formed by the yeast bubbles out of the mixture resulting in bread that doesn't rise properly. Applications Different baked products have different textures: scones should be slightly crumbly, while white bread should be light and elastic. One way to obtain the desired texture is to use flours with different protein contents. Another way is to knead the dough for different lengths of time – pastry dough is kneaded very little compared to bread. Another way is to add butter or oil, as these hinder the formation of gluten. Some people are allergic or intolerant to gluten. These people can't eat wheat products and some other grains, but can eat gluten-free foods such as rice and corn. By Patrick Mahony Try another Science by Email activity about making bread More information Science of bread View the online version Quiz questions 1. Which contains more caffeine: green tea or black tea? 2. What are Gauss' law for electricity, Gauss' law for magnetism, Faraday's law of induction and Ampère's law collectively known as? 3. Where are the only active volcanoes in Australia located? 4. What chemical is represented by the symbol Cr? 5. Which insect is responsible for spreading dengue fever? Did you know? Platypus populations on small islands are at higher risk of disease due to lack of genetic diversity. Websites Watch it! Explore the depths of the ocean in these videos. See it! See the winners of the 2011 Extreme Science Imaging competition. Recycle, Saturday 12 May at 9.00 am on Network Ten You can recycle more than just paper, plastic and glass. This episode of SCOPE is about the what, why and how of some of the more unusual things we recycle. Join Dr Rob as he puts out the rubbish and once again proves that the ordinary becomes extraordinary, under the SCOPE. Next episodes: Thursday 31 May, 4.00 pm: Future tech Saturday 2 June, 9.00 am: Trees Want to have your own episodes of SCOPE to watch whenever you feel like it? Click here to download them directly into your iTunes folder, or go here to download iTunes. Charges apply. Quiz answers 1. Black tea contains more caffeine than green tea. 2. The four laws are known as Maxwell's equations. 3. The only active volcanoes in Australia are located on Heard and McDonald Islands, in the Southern Ocean. 4. Chromium is represented by the symbol Cr. 5. Dengue fever is spread by mosquitoes. A new tool for detecting dengue fever in mosquitoes has been developed by the University of Queensland. Science by Email is a CSIRO publication. The Department of Agriculture, Fisheries and Forestry and bankmecu are proud partners of Science by Email. Editor: Jasmine Leong| Manage your subscription | FAQ

 

 

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