Can we see atoms?

Image credit: Pixabay 2017.

photos of atoms

Background

There is a large number of physical and chemical techniques available today for the analysis of substances. They provide the opportunity to gain information about the properties of atoms, molecules and ions. Infrared spectroscopy, for example, measures the vibrations of molecules. Mass spectrometry, which is widely known from TV crime dramas, gives information about the weight of molecules or ions. This information about mass can then be used to identify poisons, drugs and other substances.

However, most techniques cannot give us a direct picture of what atoms, molecules or ions really look like. Normally, conclusions about their looks are drawn from measured properties. Imagine you are drawing a picture of a house while somebody is telling you about its appearance, but you cannot see it yourself. This is how physicists and chemists use the information from their measurements to figure out what atoms, molecules and ions look like. The measurements are giving them information about substances, which corresponds to the information about the house, such as colours; size or where doors and windows are.

But are there any methods that can provide us with – let us say – a photo of an atom? The main problem is that atoms are extremely tiny. One atom in an apple is as small as the apple itself is compared to our entire Earth. Nevertheless, there are a few methods that can indeed capture pictures of atoms with the help of quantum mechanics and other cool science. A few of these methods are listed below.

Transmission electron microscopy (TEM)

Atoms cannot be seen under normal light microscopes. The reason is that the wavelength of visible light is much larger than atoms themselves are. To be able to see a sample in a microscope, the wavelength has to be smaller than the sample itself. For example, light waves are smaller than cells which is why cells observed in light microscopes. Transmission electron microscopes use electrons instead of visible light. Thanks to the wave-particle duality, electrons can behave as both waves and particles. As waves, they have a much smaller wavelength than light which makes it possible to see atoms in a transmission electron microscope. Besides the use of electrons, the working principle of a TEM is the same as that of a light microscope.

Scanning tunneling microscopy (STM)

Scanning tunneling microscopy is another microscopic technique. It is based on a quantum mechanical phenomenon called ”tunneling”. Electrons can ”tunnel”, or in other words transtition, from an atom on the tip of an extremely sharp needle to atoms on a sample surface. Needle and surface have to be at a very short distance from each other to enable tunneling. The probability of tunneling increases when the gap between the needle and the surface gets smaller. This means that electron tunneling is more likely to occur when the needle tip is above the center of an atom as compared to the tip being above the space between two atoms. In consequence, a topographic picture of the atoms on the sample surface can be obtained.

Atom probe tomography (APT)

Atom probe tomography is a very powerful technique that can provide three-dimensional images of a sample’s atomic structure. In APT, the magnification is caused by a highly curved electric field instead of electron properties like wavelength or tunneling. For this technique, atoms have to be removed from the sample surface and turned into ions, in other words they have to be ionized. To obtain three-dimensional information, the atoms are removed from the sample layer by layer, which means that, unlike the previous two methods, this technique is destructive.

The Isolation and Detection of Starch – A Practical for Science Lessons

1 Goal

In this lab you will isolate starch from potatoes and investigate if different food samples contain starch. This is done with the help of Lugol’s solution (iodine/ potassium iodide solution).

2 Introduction

Starch is an organic compounds that belongs to the carbohydrates. Carbohydrates are an energy storage for both plants and animals. Starch molecules are very long and the building blocks repeat themselves. They form long chains and belong to the so-called poly saccharides. The two building blocks of starch are amylose which forms spiral chains and amylopectin which forms branched chains. Both are built up from glucose rests which is why the chemical formula can generally be written as (C6H10O5)n. Starch can be found, e.g. in root crops and grains.

The presence of starch can be detected with with the help of Lugol’s solution which is a mixture of iodine and potassium iodide dissolve din water. Potassium iodide is added to increase iodine’s solubility in water. Iodine molecules (I2) are stored in the spiral chains of amylose when Lugol’s solution (brown solution due to the iodine) is added to the starch. This storage compound (”iodine starch”) causes a blue-black colour. A schematic of the compound is shown to the right in the figure above.

3 Materials and Chemicals

  • Two Potatoes
  • Different other foods: Flour, bacon, cheese, apples, pasta and rice are recommended
  • Lugol’s solution (= iodine/potassium iodide solution)
    – Preparation: Dissolve 10 g potassium iodide in 100 ml of distilled water. Then slowly add 5 g iodine crystals, while shaking. Finally, lter and store in a tightly stoppered brown glass bottle.
  • Knife and Spoon
  • Several Test Tubes with Gummy Plugs
  • Mortar
  • One 250 ml-Beaker and one 800 ml- or 1000 ml-Beaker
  • Heating plate
  • Linen cloth
  • Funnel
  • Two Bowls
  • Grater

    4 Implementation

    4.1 The isolation of starch

    First, the potatoes need to be cleaned and peeled. Thereafter, they are grated and put into a bowl. 500 ml of water are added and the mixture is stirred thoroughly with a spoon for at least five minutes. A linen cloth is placed in a funnel and the mixture is pressed through into a large beaker (800 ml or 1000 ml). A part of the grated potatoes, for example the cellulose, will stay behind in the linen cloth. The liquid in the large beaker needs to stand and rest for approximately ve minutes. Then more water is added, approximately 100 – 200 ml. The finely dispersed, solid starch particles will slowly settle at the bottom of the beaker. Afterwards, the
    water is decanted (= poured off). Then 100-200 ml of water are added again to
    the large beaker and decanted when the solid starch particles have settled on the
    bottom a second time. This cleaning step is repeated until the starch particles have
    a completely white colour. Afterwards, the starch is dried in a at bowl in air and
    at room temperature.

    4.2 The detection of starch

    The foods are crushed in a mortar and and small amounts of each are put into their respective test tube. The test tubes are filled up to a third with water and shaken vigorously. In case not all the food particles are suspended, the test tubes are heated in a water bath (water bath = a 250 ml-beaker filled with water and the test tube inside is heated carefully on a heating plate, the test tube is afterwards cooled under owing, cold water). Then one drop of Lugol’s solution is added to each test tube and the test tubes are shaken with a gummy plug on top.

5 Questions for Discussion

1. What is observed macroscopically when iodine is built into starch molecules? What happens when no starch is present?

2. Which function does starch have?

3. In which foods do you expect to detect starch? In which foods should there be no starch?

4. Do the results in the table match your expectations? If not, why could they be different?

References

Image retrieved from: Petra Mischnick, Skolan för kemivetenskap , Kungliga Tekniska Högskolan, Stockholm, 11 January 2013 (https://www.kth.se/che/archive/arkiv/molnov-1.272910, 30 August 2017).

What happens during cooking, frying and baking?

cooking frying baking

Cooking and frying cause chemical changes in food and lead to the formation of new substances. One obvious change is that many foods like meat, eggs or potatoes turn brown when being fried. This is caused by a chemical process called the Maillard reaction. This reaction takes place between an amino acid and a reducing sugar. In the reaction, the carbonyl group of the sugar reacts with the amino group of the amino acid and forms a new substance with a brown colour and a better taste. There are many different sugars and amino acids in food which is why the number of different brown, well-tasting products is very large. The Maillard reaction requires the addition of heat and does not occur before 140 degrees Celsius. This reaction is responsible for the colour and taste of a great variety of foods. Besides the well-known colour of fried (or grilled) meat, eggs, potatoes and other vegetables, it is also resposible for the brown colour and taste of toasted bread as well as roasted coffee beans.

Another process which happens during both frying and cooking is the denaturation of proteins. Large protein molecules are normally folded in a very specific way. During denaturation they unfold. This process can be compared to unfolding a piece of Origami art until only a sheet of crumpled paper is left. These crumpled proteins can easily become entangled with each other in a process called coagulation. In addition, the cell walls of vegetables like potatos and carrots are broken down by high temperatures when being cooked or fried. This makes them easier to digest for us humans as compared to eating them raw.

Like for frying, the Maillard reaction plays an important role for baking too and causes the brown colour cakes take on when they are placed in an oven. Other browning reactions like the caramalization of sugars take place as well. Caramalization is the oxidation of sugars which turns them into brown products. It should be noted that caramalization happens at different temperatures for various sugars. Fructose, for example caramalizes at only 110 degrees Celsius, while 160 degrees are necessary to caramalize glucose. The denaturation and following coagulation of proteins is essential for baking too because it results in the stiffening of the dough.

Today, the chemical reactions caused by so-called raising agents are important as well. Baking powder and self-raising flour normally contain a substance called sodium bicarbonate (also known as baking soda) and a solid acid. When water and heat are added this mixture releases the gas carbon dioxide which gives cakes their fluffy textures. Evaporating water further contributes to this process which is called expansion.

Fluffy cakes as we know them today first entered the kitchen in the 18th and 19th century. Before that, cakes were generally flat and rather heavy, like fruited tea cakes for example. During the time of the first fluffy cakes sodium bicarbonate had not been discovered yet. Instead, yeast was often used as a raising agent and it is still used today in some countries to bake bread. Another method was to beat eggs before adding them to the dough until they contained enough air bubbles, a method that could take a long time and required strong arm muscles.

The reactions taking place during deep-frying resemble in parts the ones during cooking and frying. The Maillard reaction, the denaturation and following coagulation of proteins as well as the break-down of cell walls happen here too. But due to the higher temperatures even more reactions like oxidations and polymerizations can take place, even in the frying oil itself. Another problem is that while the frying oil extracts nutriants like vitamins and minerals, it also creeps into the food and adds high numbers of calories. For this reason, deep-fried food is normally less healthy than its regularly fried or cooked counter parts. This can easily be shown by the example of a large baked potato which normally contains about 220 calories and 1 g of fat. If the same potato is cut up and turned into chips (or French fries), it will contain almost 700 calories and 34 g of fat. In conclusion, deep-frying creates very well-tasting foods, but it is important not to consume them on a regular basis.

Scientific Methods in Archeology

Image credit: Pixabay, 2017.

There are few fields that are as interdisciplinary as archeology. From radiocarbon dating to ground-penetrating radar, Archeologists use a wide range of scientific methods to gain insights into historic cultures. But which scientific methods are actually most useful to archeologists? And what kind of information do they provide? I have interviewed Professor Kerstin Lidén, an archeologist at Stockholm University, to find out more about this. According to her the three most important scientific methods for archeology are ground-penetrating radar (GPR), mass spectrometry and X-ray fluorescence (XRF).

Ground penetrating radar (GPR) is a physical method also used in geosciences. It emits radio waves into the ground and detects their reflections caused by burried structures, for example ruins of castles, temples or settlements. GPR is popular because it offers the possibility to identify the location and the form of buildings and monuments without digging them up.

Mass spectrometry is a chemical technique that normally helps to determine the composition of unknown substances, as many of us have seen in TV crime dramas. In archeology, however, it is used differently. Here, its main task is to identify different isotopes (atoms of the same element with different neutron numbers). One example is the identification of the carbon-14 isotope, a radioactive carbon isotope used for radiocarbon dating. As long as plants, animals or humans live they incorporate carbon-14 into their systems, either by photosynthesis or by eating plants. No new carbon-14 enters the organism after death and conclusions can be drawn about age from the radioactive decay of carbon-14 and its half-life.

Isotope analysis can teach us even more about long-deceased organisms. Carbon and nitrogen isotopes are used to reconstruct diets, while oxygen isotopes can help to determine geographic origins and environment. Strontium and lead isotopes, on the other hand, can give clues about population mobility which means seasonal and/or permanent migrations.

X-ray fluorescence (XRF) is popular to gain information about the chemical and elemental composition of historic artefacts made from metal, glass or ceramics. This method works by bombarding the archeological sample with X-rays or gamma-rays which causes the removal of inner-shell electrons from the sample atoms. As a response, electrons from outer-shells will ”fall” into the inner-shells and simultaneously emit energy in the form of characteristic X-rays. These can be used to identify the chemical composition of the artefact.

Besides the three techniques described here, there are many other, some pretty cool, methods in operation by archeologists. Lidén gives the example of one colleague who used laser scanning to study the writing on rune stones. This analysis showed that different people had carved on the same rune stone. According to Lidén it is like analysing hand writing, only that it is over 1000 years old.

Lidén also says that the goal of archeologists is to get ”life history details of individuals that have been dead for thousands of years”. The information from different scientific techniques has to be put together like a puzzle to gain this information. In the end, archeologists will know what an individual ate at different points in life, where he/she lived and if there was movement between different geographical areas, which diseases the person might have had and when the individual died. This kind of information is important to understand variations and similarties between different cultures and populations.

What Lidén is most proud of in her own work was showing that two archeological cultures in Sweden were really two different cultures. She and her team were able to show that they did not only use different materials and burried their dead differently, but also actually ate different foods. This had long been disputed in Sweden before.

 

The chemistry of soaps and why it matters

Soap is made via a chemical reaction between a fat and sodium hydroxide (NaOH). The reaction is called saponification and produces salts which consist of sodium ions and fatty-acid ions. The latter have one long chain of carbon atoms each. These sodium-ion fatty-acid salts are very good at removing dirt and we also call them soaps. Their secret is that the non-polar, long carbon chains of the fatty acids are aranged in spheres around the non-polar dirt particles. The opposite chain ends, where the polar sodium ions are attached, face the polar water. These arrangements are called micelles and they can dissolve dirt from your clothes or skin.

Making soap in this way is actually quite environmentally friendly. Sodium hydroxide is normally used in the form of lye which is made by leaching wood ashes with water. Historically, the fat has often come from animals, but today fats from plants, such as olive oil or grapeseed oil, are used since they create nicer soaps. In summary, soap can today easily be produced using only renewable sources from plants.

Sounds like soap making is an eco-friendly process? Yes, but unfortunately reality looks very different. When I researched this topic, I was really shocked when I found out which substances are actually being put into these products, despite better knowledge.

Let us start by talking about the actual cleaning agents, the substances that remove the dirt. Traditionally, soaps as described above have been used for this task and I believed that this was still the case. But it turns out that today most cleaning agents are made from petroleum instead of vegetable oils. These petroleum-based chemicals work the same way as real soap does by forming micelles around dirt particles to dissolve them. They are, for example, found in laundry detergent and liquid body wash. Only bar soaps still contain the more environmentally benign, real soaps. But be careful, not all of them do. You should check if it actually says ”soap” on the packaging to be sure.

There are even more reasons why solid soap products are more environmentally friendly. On average the production of bar soap consumes five times less energy than liquid soap. Another important factor is water. Liquid soaps as well as liquid laundry detergents contain 80 % more water than their solid counterparts. In addition, liquid products come in non-reusable plastic bottles, while the solid products come in cardboard packaging.

Besides the petroleum-based cleaning agents, manufacturers often add a range of other questionable chemicals to liquid soaps. One famous example are parabens which are added to about 85 % of all liquid cosmetic products to prevent bacteria and fungus growth. Parabens can be mistaken for estrogen by the body which has been linked to both breast cancer and reproductive issues. It will be interesting to see if they could be related to the recently reported drop in sperm count among Western men. Also, paraben substitutes like phenoxy ethanol should be used with caution. Bar soaps and other solid cosmetic products, on the other hand, do not need any preservatives and are a healthier choice.

Some harmful chemicals could also be hiding under the label ”fragrance” or ”parfume”. Their compositions do not have to be revealed as they are considered trade secrets which leaves the consumer clueless about what they are made of. At least one villain chemical, called phthalates which has been linked to many health issues, is often included in parfumes as a preservative.

So, the bottom line is: use bar soaps, make sure that it contains real soap and check that all contents are revealed. As for laundry detergent, washing powder is better than liquid detergent. You can also easily make your own laundry detergent and bar soaps at home.

 

The physics behind musical instruments

physics-and-music

One of the best museums I visited last year was the Haus der Musik – Sound Museum in Vienna. It is an amazing place where you can among other things compose your own music and try to conduct the famous Vienna Philharmonic Orchestra. But there was one part of the exhibition that I enjoyed even more, the one about instruments. By standing in a giant mouth piece for wind instruments or a giant hollow percussion body you could experience first hand how music is created. And yes, it has everything to do with physics and science.

Sound is created when an object vibrates. The vibrations cause the particles in the air around the object to vibrate too. The particles in the air then bump into their neighbors setting them into a vibrating motion as well which lets the vibration travel further. For this reason, sound is often defined as vibrations that travel through air and are detected by a human’s or animal’s ear. But it should be said here that the medium does not necessarily have to be air. Whale ears, for example, pick up vibrations that are transported through water. In physics, vibrations are commonly described as waves.

Special about music instruments is that they create so-called standing waves instead of random vibrations. In a standing wave some points, the nodes, of the vibration remain fixed while the rest vibrates with maximum amplitude which refers to the highest and the lowest points of the wave. It is these standing waves that we experience as harmonic tones when listening to music. Other irregular, random waves that are not standing, we hear as noise instead.

The properties of the vibration’s standing wave can tell us how we experience the tone. One important property of waves in physics is their frequency which describes how many waves pass one point during a specific time. The larger the frequency, the more waves pass the point and the more high-pitched we experience the tone. In contrast, the smaller the frequency, the less waves pass and the lower the tone sounds. The amplitude (remember the highest and lowest points of the wave), on the other hand, tells us how loud a tone is. The larger the amplitude, the higher the wave and the louder the tone sounds, whereas a smaller amplitude gives a softer tone.

Musical intruments can create vibrations in three different ways as explained in the infographic above. There are persussions/drums, wind instruments and string instruments. Percussions, no matter if bell or drum, have a hollow body. When being hit with sticks, hands or something else this hollow body starts vibrating and creates the tone we hear.

Wind instruments include brass instruments, such as trumpets and saxophones, as well as woodwind instruments, such as flutes. They all have a mouth piece and a hollow tube. When the player blows into the mouth piece, an air column inside the tube is set into a vibration motion and a tone can be heard.

String instruments work through the vibration their tensioned strings. The vibrating motion can be started by different methods. The strings can be plucked, like for guitars or harps, bowed, like for violins or cellos, and hit, like for pianos.

 

How does breathing change wine?

It is this time of year where you can sit outside in the evenings to hang out with friends. Throughout this time many bottles of wine are shared and enjoyed. During such an evening with several bottles of red wine, me and some friends noticed that the taste of one particular red wine became better the later the evening got. This was not because we were getting more and more drunk, but rather due to a process called ”breathing” or ”aeration”.

Breathing refers to chemical reactions taking place between the wine and the oxygen in air that start once the bottle is opened. Generally, two processes occur during breathing, these are evaporation and oxidation which cause the wine to release new aromas and flavors.

Evaporation is the transition from the liquid to the gas phase and some volatile compounds easily evaporate in contact with air. Examples are sulphur containing substances formed by sulphites in the wine. Sulphites are added to wine to protect it from bacteria. The second process, oxidation, is in this case the reaction of wine compounds with the oxygen in air, a similar process to the rusting of iron  (where iron reacts with the oxygen in air). Substances in wine sensitive to oxidation are various poly-aromatic compounds like catechins and anthocyanins. They are the flavor-rich, dark pigment molecules that give red whine its color.

It is worth mentioning that the production of flavor-rich, dark pigment molecules like anthocyanins and other poly-aromatic compounds in grapes stops at temperatures that remain constantly around 30 degrees Celsuis. This leads to a decrease of flavor-rich compounds and is one of many reasons why climate change is threatening to ruin the global wine production.

Additionally, ethanol, in other words alcohol, is sensitive to oxidation as well if a wine bottle is opened too long, for example over several days. During the oxidation of alcohol acetaldehyde and acetic acid are formed. Acetic acid is the main compound in vinegar and the reason wine turns sour after having been opened too long.

The last example shows that unlimited breathing is not good for wine either. In addition, not all wines benefit from breathing. Especially, older wines can deteriorate very quickly when in contact with air. Young, red wines, on the other hand, like the one my friends and me had, benefit a lot from breathing. White wines normally lack the dark pigment molecules that change during oxidation. For this reason breathing does mostly not alter the taste or white wines.

So, how long do you need to let a red wine breathe? Generally, you should taste a wine before deciding if it needs breathing at all. As bottle necks are quite narrow, they do not provide a lot of contact with air and the wine will need at least 30 to 60 minutes to breathe on its own. However, there are ways to speed up the process. For example, you could pour the wine into a decanter, a vessel with a neck for pouring and a very broad bottle body to provide a large surface area for the wine to breathe. You could also pour the wine back and forth between two vessels or just swirl your glass before drinking the wine.

I hope the weather is nice were you are, so you can enjoy a glass outside with friends tonight.

New magnets for wind power plants

Image credit: Johan Cedervall, 2017. CC BY-SA IGO 3.0. This material is a strong magnet investigated for the use in wind power plants and other applications.

Almost everyone has seen magnets in action when sticking a birthday card or the drawing of a child to a refrigerator. Some might have even used one when taking a compass on a hike. There is one more important application for magnets that most of us have seen: wind power plants. The generators inside wind power plants use very strong magnets to create electricity. These magnets are normally made from the elements neodymium, iron and boron.

While iron and boron are are relatively easy to extract and separate from their minerals (or stones), neodymium is a rare-earth element. There are in total 17 rare-earth elements and despite their name, they are actually quite plentiful in the Earth`s crust. The problem is that these elements tend to occur together in the same minerals which makes their extraction and separation extremely difficult and expensive. In addition, China stands for 85 % of all rare-earth element production which provides a monopoly position enabling it to dictate prices and make other countries dependent. Besides, there are strong environmental as well as health and safety concerns about the mining procedures used in China.

For these reasons research is carried out to find new neodymium-free or rare-earth-free, strong magnets. I have spoken to Johan Cedervall, a PhD student in the Inorganic Chemistry group at Uppsala University, who is trying to make new rare-earth-free magnets for wind power plants and other applications. Cedervall is working on magnetic materials composed of iron, boron, phosphorus and silicon, all abundant materials which are relatively easy to extract from their minerals.

To produce his magnets, Cedervall melts the elements together in an electric arc (basically a permanent, artificial lightning) at 1500 to 2000 °C (2732 to 3632 °F) under argon atmosphere. This procedure results in a highly magnetic, grey compound as seen in the image above. According to Cedervall, his materials are generally a bit less magnetic and easier to demagnetize than conventional neodymium-based magnets, which is a disadvantage. But they are also much cheaper thanks to the absence of neodymium.

Nevertheless, Cedervall says, that the goal is to find even stronger rare-earth-free magnets than his for the use in wind power plants. The problem is that weaker magntic materials have to be used in larger amounts to reach the effect of a neodymium-based compound. For this reason, the search for strong, rare-earth-free magnets is ongoing.

Cedervall believes, that we will see a shift to rare-earth-free or rare-earth-lean (containing smaller amounts of neodymium) magnets in the near future. Wind power plants are being built at a rapid pace all over the world at the moment. To maintain this development, industry will sooner or later be forced to turn to alternative magnets. The German company Enercon has, in fact, already implemented neodymium-free technology into their wind turbines. In addition, magnetic materials called ferrites, for example strontium iron oxide, have already started to replace neodymium in other applications.

When asked which results of his research he is most proud off, Cedervall answers, that these are actually not related to wind power plants. All magnets lose their magnetic properties at a certain temperature when they are heated. This point is called Curie temperature which is between 500 and 600 °C (932 and 1112 °F) for Cedervall`s materials. He has found that this point can be tuned by the gradual substitution of iron with cobalt. A higher cobalt content decreases the Curie temperature, while a lower one increases it. This result could be interesting for building magnetic refrigerators that are safer and more environmentally friendly. The details of this application are a story for another time.

Making batteries with sulfur

Image credit: Ben Mills.

 

The yellow powder in the image above is the element sulfur, which I am sure many people have seen before in school science lessons. Normally in chemistry classes, we are mainly taught about how bad the compounds made from this element smell. Examples are hydrogen sulfide with the distinct smell of rotten eggs and sulfur oxides. But could there be more to this powder? To find out, I have talked to Dr Matthew Lacey at Ångström Advanced Battery Center who is trying to build rechargeable batteries from sulfur.

Lacey is working on lithium-sulfur batteries (Li-S batteries) which consist of sulfur as the positive electrode (cathode) and lithium metal as the negative electrode (anode). When discharging (or using) these batteries, lithium and sulfur react to form the compound lithium sulfide and the process is reversed during charge. The advantage is the light weight of both sulfur and lithium, which leads to a very high energy density by weight. This gravimetric energy density of the batteries themselves could be up to two or three times higher than for conventional lithium-ion batteries according to Lacey. In addition, sulfur is abundant as well as a biproduct of the oil industry and, for these reasons, very cheap.

Nevertheless, Lacey admits that Li-S batteries also still have some drawbacks compared to conventional lithium-ion batteries. During discharge, sulfur dissolves in the electrolyte (the liquid placed between positive and negative electrode), where it can exist as a large number of different compounds called ”polysulfides”. These polysulfides can react with each other or be transported to the lithium foil (negative electrode) and react there. Especially, the reaction between polysulfides lithium results in very short lifespans for Li-S batteries. Strangely, the dissolution of sulfur in the electrolyte is an important part of how Li-S batteries work, but at the same time it is the source of severe problems. Another disadvantage is that, although the energy density per weight is high, the energy density per volume of Li-S batteries is rather low since lithium and sulfur are light, but have low densities.

Lacey is mainly working on a part of the battery called the ”binder”. In order to build a Li-S battery, sulfur and conductive carbon powder have to be attached to a conductive substrate, the current collector. Binders are the glue that stick sulfur and carbon powder to the current collector surface. Together these components form the positive electrode. Lacey is trying to find new binders that can do more than just be the glue of the electrode. The battery scientist wants his binders to interact with the polysulfides in the electrolyte (described above) to extend the lifetime of Li-S batteries. Lacey and his co-workers have been quite successful in this quest during the past years and more about it can be read in this recently published article.

The battery scientist is also proud about a new method called ”intermittent current interruption” that he developed during the past years. This technique makes it possible to track the resistance in batteries over long periods of time and can be used for all kinds of batteries, not only Li-S batteries.

Despite the challenges, Airbus Defence and Space are developing Li-S batteries for the Zephyr “High-Altitude Pseudo Satellite”. Li-S batteries are the only rechargeable batteries with a high enough energy density per weight to run this ”pseudo satellite” when sunlight is not available in the shadow of Earth. In addition, the UK based company OXIS Energy is working towards the commercialization of Li-S batteries.

Nevertheless, Lacey believes that due the low cost of lithium-ion batteries, they will keep dominating most markets such as electric cars and portable electronics in the foreseeable future. But, he also says, that Li-S batteries are still interesting for applications where battery volume and cost are less important. Examples are defence or space where Li-S batteries could power soldier equipment or satellites. Hybrid electric trucks could be another future market for Li-S batteries with battery volume being less of a problem for trucks than for smaller cars.

 

 

 

What I learned from one day without waste

Last week I did an experiment. I collected all the waste I produced during one day. The result you can see in the image above. The following day I pledged to live trash free. This is how it went.

During my normal day I produced trash from the wrappings of my lunch and dinner. There is also the price tag of a top I had bought a week earlier and a small plastic bag I used to transport my tooth brush and tooth paste for a visit at the dentist. Finally, there are the packaging of a tea bag and of a post-workout protein bar. This does not seem much, but projected over a week, month or year, I am generating mountains of trash, wasting resources and energy in the process.

What followed was a day without trash. I pledged to not create waste for one day via the organization Live Zero Waste which helps people to live trash free. The day happened to be a holiday in Sweden, which was good in some aspects. For example, luckily, I was far away from the paper coffee mugs and tempting, wrapped lunch sandwiches sold by the university cafeteria.

In the morning, my only challenge was that I could not empty my milk carton to put milk into my coffee. So, I had it black and saved the milk for the day after. This option I would not have had if I had pledged for a week, month or year (which you can do also). But it still gave me an idea about how much trash I create from the packagings of milk, juices, cereals and so on.

In the afternoon, I was invited to a barbecue lunch with friends. I took my own camping plate, mug and cutlery with me to make sure I would not produce any waste from paper plates or plastic cutlery. The next problem was to find a small gift I could take for my friends who invited me. Normally, I love to buy chocolate for these occasions, but that would have meant indirecly creating waste from the packaging. I panicked for a while and eventually picked some maybell flowers that were blooming in the forrest behind our house and made a nice gift.

Then there was rugby practice in the evening. After splintering a bone in my left ring finger last year, I keep it taped during practice with sports tape. According to Live Zero Waste you are allowed to take medicine during your pledge despite of the packaging (and, yes, you are also allowed to use toilet paper). I decided that this applied for the tape too. Nevertheless, I realized that I must have created mountains of trash from tape during the past year. Finally, I had to switch my usual protein bar for a banana as a post-workout snack.

Now, why would you do all this? Living trash free is obviously quite a challenge.

The answer is climate change and the environment. For every kilogram of waste we throw away, seven more are created during the manufacturing process. Production, transport and packaging of everything we buy consumes resources, energy and produces carbon dioxide. When it comes to climate change, we sometimes tend to focus only on the impact of our travelling by car and plane. But the truth is that everything we buy from chocolate bar to car also has a great impact on climate change and the environment.

Waste is a representation of this impact. It also shows that besides taking the bike or the bus to work, there is much more every single one of us can do to fight climate change and protect the environment. Therefore, waste is also a representation of the choices we personally make to fight climate change and pollution. These issues are not only about what governments decide, but also about the personal choices everyone of us makes.

The good thing is that everyone can choose to create no or less waste. Basically, this means two things. 1) Buying less new stuff which I imagine is very hard for most of us including myself. 2) Avoiding packaged everyday items like food or toiletteries which makes life more challenging.

Everyone has to make their own decisions on if and how they want to reduce their waste. I can highly recommend to pledge one waste free day with Live Zero Waste to figure that out. The day has shown me very vividly which changes I can personally make for a more environmentally friendly lifestyle. It is really easy to pledge here and you will get mentors to help you.

This is what my waste free day has taught me. I have learned that homemade gifts or activity gifts are more environmentally friendly than bought ones. My goal is now to learn how to make my own chocolates to give away. Another change I want to make is to generally switch my post-workout protein bars for bananas and other fruit. Next, I am planning look into getting a reusable splint for my finger that I can use during rugby practice instead of tape. Finally, I also have decided to more often bring my own home-made lunch to work and to always take my own cup down to the cafeteria to get coffee. You can find even more tips by Live Zero Waste here. Good luck with you own challenge!