Science! Monthly The Science of Celebration by EPSA

The Science of Celebration December Edition 2021

Introduction Dear readers, Time flies and we are already on to the last publication of Science! Monthly of this year! As this year is coming to an end, lots of celebrations are taking place during the holidays that will start soon. To keep you sweet during the joyful and cozy month and the holidays, this edition will unravel the science behind a topic you might not have even thought about, namely ‘celebration’. In this topic, you will read about how fireworks work. Furthermore, as Christmas is coming, you will read about the best way to roast a turkey, the nostalgic aroma of pine from Christmas trees, how candles burn, and why flames are going up. Lastly, we will go back in time and take a close look at the jack-o-lanterns and their potential, other than scaring away evil spirits. Enjoy reading this edition of Science! Monthly! And wishing you a joyous Christmas all the best and luck throughout the coming year! Enjoy your reading!

Yong Xin Cao Science Coordinator 2021/2022

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The Art of Fireworks Usually, around the end of the year, houses are being thoroughly cleaned, tables are prepared for luxurious dinners, the champaign will be joyously opened and drunk, and on January 1 exactly at midnight fireworks will cover the sky in beautiful colours, thereby welcoming us to a new prosperous year. st

Fireworks are the symbol of the introduction to a new year. They are explosive devices using pyro technology and their aim is to entertain the crowd. Fireworks appear in many different bright colours. These colours are often formed by pyrotechnic stars which are small pellets containing metal powders, salts, or other substances that will burn a particular colour with intense light or create a spark effect after ignition. The pellets contain five general components:

Figure 1: fireworks 1. Fuel Fuel is needed to allow fireworks to ignite. The most often used fuel is gunpowder consisting of 75% potassium nitrate (KNO ), 15% charcoal (C), and 10% sulfur (S). Gunpowder has an energy density of 3 megajoules per kilogram. 1-4

Oxidizer Oxidizers are used to provide oxygen to allow for the combustion of fuel. Frequently used oxidizers are nitrate (NO ), chlorate (ClO ), and perchlorate (CIO ). For example, potassium nitrate (KNO ), used as fuel, can also function as an 2,3

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oxidizer. Strontium nitrate, producing the red colour in fireworks as well, works as an oxidizer simultaneously.

Salts Salts produce an intense colour when fireworks burn. The science behind the different colours produced by different salts lies in the physics area. The colours come from a combination of luminescence and incandescence. Different arrangements of electrons in the outer shells of the salts’ nucleus result in different absorptions of energy and therefore emissions of different wavelengths. The emission of light when heated is luminescence. While incandescence is when the light is produced by heating a metal until it glows, usually this light is red, orange, yellow, blue, or white. Figure 2 displays the colours that can be attributed to a certain element.

Binders Like tablets need binders to not disintegrate the moment they are taken out of the machines, fireworks need them as well to function properly. Binders are usually starch or sugars. The most common binder is dextrin dampened with water.

Chlorine donor To strengthen the colours chlorine donors are used in some mixtures. Oxidizers can also function as chlorine donors.

2,4

Figure 2: elements and the colours of firework

Anatomy of fireworks3,5 The anatomy of fireworks is slightly different depending on the type of firework. However, figure 3 gives a general overview of the anatomy. A firework consists of a mortar which is a cylinder-shaped object containing the shell. The shell is usually made from paper and it is shaped likea sphere. It is put on a lift charge, containing black powder, so that the shell can launch out of the mortar. The timed fuse penetrates through the bottom of the sphere and activates the burst charge which is located in the middle of the shell. This EPSA – European Pharmaceutical Students’ Association

burst charge will ignite the stars within the firework. Those stars located within the shell will create a special sound and light when ignited.

How fireworks work6 To shoot fireworks, the fuse must be ignited by fire. When charged, the gunpowder will be ignited and propel the firework into the sky by its power. While the shell propels into the sky, the timed fuse is slowly charging. At a certain point in the sky, the fuse will set off the gunpowder in the central part of the shell. The gunpowder will ignite and trigger the stars, which in turn will explode in a certain pattern and particular colour(s). Depending on the organisation of the stars within different compartments of the shell, the patterns can be altered.

Figure 3: the anatomy of fireworks

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All I want for Christmas is Science The fragrance of Christmas trees As the winter months are coming and people retreat more to their homes, Christmas trees cannot be missed out of the heated living rooms around Christmas time. Particularly, the aroma of Christmas trees is nostalgic and refreshing. This fragrance of pine trees consists of pinene (C H ). Pinene occurs in nature as two isomers: alpha-pinene and betapinene. Both can be found in the resin of the trees. Generally, alpha-pinene is more abundant than beta-pinene. Alpha-pinene has a turpentine-like fragrance and is found in volatile oils in pine trees. Beta-pinene has the same fresh, woody, turpentine-like odour. It is a compound emitted by forest trees. Pinenes are easily flammable, hence Christmas trees and pinecones burn well. The inflammability can be derived from its chemical formula as well, as it has 10 carbons and sixteen hydrogens, easily allowing for the combustion reaction. 7

Figure 4: Christmas tree Pinene is part of the family of compounds named terpenes. Terpenes are organic compounds that are produced by plants. They provide smells of woods, but they can also react with chemicals in the air to create aerosols that can act as a seed for the formation of clouds, thereby allowing their creation from water vapour. These cloud covers have a cooling effect and can be visible as a blue haze due to the light-scattering effect on sunlight. Other minor volatile compounds given off by pine trees are limonene, myrcene, phellandrene, and camphene. Furthermore, non-terpene constituents such as bornyl acetate, an ester, contribute to also the clean, fresh pine fragrance.

Figure 5: pinenes

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Candles and how they burn8,9 Whether you have them at home all the time, or only during a special occasion, for example during your birthday or during Christmas, candles, which existed hundreds if not thousands of years ago, are still used in our modern society nowadays. They function as a great lighting system and symbolise peace and serenity. The composition of candles is not complex. Candles contain two parts, the wick, and the wax. The wick is the little part that pokes out at the top of the candle. This part burns as a flame engulfs it. The wick is commonly a braided string of cotton. To produce light, candles use heat. This conversion goes through the combustion process, where substances are burned in the presence of oxygen to produce heat and light. Wax which plays the role of fuel is composed of carbons. It burns in the presence of oxygen and produces carbon dioxide. As for the mechanism, once the wick is lit by a fire, wax that is close to the wick begins to melt. The wick absorbs the liquid wax, which has melted and pulls in upwards as a result of capillary action. The heat of the fire vaporises the molten wax. Along with the oxygen in the air, it produces a continuous flame.

Figure 6: candles

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Why does the flame always point up?

Have you ever seen a flame that points down? According to the laws of physics, that should not be possible on earth. As a candle burns, nearby air is heated, and the flame rises. Warm air moves up, and at the same time, cooler air and fresh oxygen are added to the bottom of the flame. Thus, when heating cooler air, the flame rises, and at the same time, it is replaced by cooler air at the bottom of the flame. This cycle is continuous and results in the elongated shape of the flame-like teardrop. This shape is also largely possible due to the gravity of the earth. In a place with minimal gravity, and where up and down does not exist, the candles’ flames are spherical instead of teardrop-like as there is no up direction for heated areas to rise. Therefore, it is not possible to create a convection current.

Figure 7: convection

Christmas turkey – have you thought about the science behind it?10,11 When one thinks about the food for Christmas, it is unacceptable to forget the delightful roasted Christmas turkey. Most turkeys are roasted, and as they are in the oven, the meat changes from a raw pink colour to a cooked white colour. The meat is made up of muscle fibers among others such as tissue and fats. These fibers are formed of filaments: actin and myosin. In the oven, the high heat causes these protein filaments to denature, thereby contracting the muscle. Bonds within and between proteins crumble and unravel, resulting in the meat becoming tender. The connective tissue which constitutes proteins such as collagen, elastin, and reticulin, when subjected to heat, breaks down as well, causing a soft, gelatinous consistency, resulting in a better texture. However, when overcooking these proteins, the texture changes and the turkey becomes dry and tenacious. While undercooking it results in a tough texture due to not breaking the connective tissue easily. To prevent overcooking, aluminum foil can be used to protect the breast as it deflects the heat. According to science, the perfect turkey can be cooked when placed in an oven between 140 and 200ºC. These temperatures lead to Maillard reactions so that chemicals can be released thereby giving the turkey flavour. This reaction is a chemical reaction between reducing sugar and amino acids. It creates colour (browning of the meat) and flavours, such as furans (burnt, meaty), pyrazine and thiophenes (roasted), and furanone (caramel, sweet). Turkeys consist of up to 60% water, most of which is bound to proteins. When cooking turkey, water molecules are released and contribute to the tenderness. This reaction is a condensation reaction; therefore, water is released following the Maillard reaction. If overcooked, too much water evaporates, resulting in dry turkey. EPSA – European Pharmaceutical Students’ Association

As for basting, according to science, the process of brushing fats and water over the meatdoes not make meat more tender. The skin of the turkey prevents the juice from getting into the meat. However, basting the legs and wings has a favourable effect as the juices slow down the cooking of these parts. This ensures that the whole turkey gets a sufficient amount of time in the oven to keep the tender texture throughout.

After finishing the turkey along with the rest of the dinner, sleepiness can overwhelm you. Amino acids in turkey can make you sleepy. Tryptophan for example is an amino acid that can be found in high levels in turkey. It is a precursor of serotonin and can make you sleepy. Another reason could be due to the large consumption of food. Digesting takes a lot of energy which in turn can make you tired.

Figure 8: Roasted turkey

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Jack-o-lantern scaring away microbes During Halloween, it is a tradition to carve out pumpkins. The tradition started in Europe. Residents would carve beets, potatoes, and turnips to scare away evil. When the concept moved to the Americans, these objects were not available. Americans started to use pumpkins instead to keep evil away. However, no science proves the concept of chasing evil away by using jack-o-lanterns. However, Canadian scientists have found that these jack-o-lanterns are very useful at removing the pollution out of the soil and storing them into the pumpkins. The scientists found out that pumpkins could detoxify areas polluted by dioxin, a toxin that can poison the bodies of both humans and animals. Dioxin is very dangerous and can be removed by burning it at very high temperatures. The use of pumpkins would be a more environmentally friendly process to remove this toxin.

Besides the detoxifying effect, these jack-olanterns are scaring away microbes. Scientists have found that substances located in the skin of the pumpkin kill harmful microbes that try to rot the pumpkin. Scientists further investigated these protective proteins and found that they are effective in some common human infections . 12

Figure 9: Jack-o-lantern Some interesting pumpkin facts Did you know that: • Pumpkins consist of 90% water? • The largest pumpkin pie ever weighed 3,669 pounds and was 20 feet? • Pumpkin is a fruit?

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References [1] ScienceNewsforStudents. Fireworks shower the skies with science. [Online]. Available from: https://www.sciencenewsforstudents.org/article/how-fireworks-shower-skies-science. [Accessed at: December 9, 2021]. [2] PennToday. The chemistry behind fireworks. [Online]. Available from: https://penntoday.upenn.edu/news/chemistry-behind-fireworks. [Accessed at: December 9, 2021]. [3] Ontario Science Centre. The Science of Fireworks. [Online]. Available from: https://www.ontariosciencecentre.ca/science-at-home/diy-science-fun/the-science-offireworks. [Accessed at: December 9, 2021]. [4] Compound Interest. The Chemistry of Fireworks. [Online]. Available from: https://www.compoundchem.com/2013/12/30/the-chemistry-of-fireworks/. [Accessed at: December 9, 2021]. [5] ThoughtCo. The Science Behind Firecrackers and Sparklers. [Online]. Available from: https://www.thoughtco.com/how-fireworks-work-pyrotechnics-science-607860. [Accessed at: December 9, 2021]. [6] Planet-Science. How do fireworks work? [Online]. Available from: http://www.planetscience.com/categories/over-11s/technology/2011/11/how-do-fireworks-work.aspx. [Accessed at: December 9, 2021]. [7] Compound Interest. The Aroma of Christmas Trees. [Online]. Available from: https://www.compoundchem.com/2014/12/19/christmastrees/. [Accessed at: December 9, 2021]. [8] National Candle Association. Candle Science. [Online]. Available from: https://candles.org/candle-science/. [Accessed at: December 9, 2021]. [9] Science ABC. Science Of Candles: How Do They Work? [Online]. Available from: https://www.scienceabc.com/nature/wonders-of-nature-how-do-candles-work.html. [Accessed at: December 9, 2021]. [10] Institute of Food Science + Technology. The food science of Christmas turkey. [Online]. Available from: https://www.ifst.org/news/food-science-christmas-turkey. [Accessed at: December 9, 2021]. [11] The Pipettepen. The Science of Thanksgiving Turkey. [Online]. Available from: http://www.thepipettepen.com/the-science-of-thanksgiving-turkey/. [Accessed at: December 9, 2021]. [12] Columbia Daily Tribune. [Online]. Available from: https://eu.columbiatribune.com/story/news/columns/2020/10/28/carving-out-sciencepumpkins/6039347002/. [Accessed at: December 9, 2021].

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References for pictures: Front page image: https://unsplash.com/photos/iXfrdygCXsQ by Mohammed Shamaa Figure 1: https://unsplash.com/photos/Dn7P1U26ZkE by Arthur Chauvineau Figure 2: created originally. Figure 3: https://www.ontariosciencecentre.ca/science-at-home/diy-science-fun/the-scienceof-fireworks by Ontario Science Centre. Figure 4: https://unsplash.com/photos/7wYNbD4tFAw by I. Figure 5: Vespermann, Kele & Paulino, Bruno & Barcelos, Mayara & Gabriel Pessôa, Marina & Pastore, Gláucia & Molina, Gustavo. (2017). Biotransformation of α- and β-pinene into flavor compounds. Applied Microbiology and Biotechnology. 101. 10.1007/s00253-016-8066-7. Figure 6: https://unsplash.com/photos/bdVmIkx_gIs by Sixteen Miles Out Figure 7: https://candles.org/candle-science/ by National Candle Association Figure 8: https://unsplash.com/photos/fXxsNyiqTio by Claudio Schwarz. Figure 9: https://unsplash.com/photos/xVG-TpHG2NY by Łukasz Nieścioruk

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