It has often been said that you can't unscramble an egg. But you might be able to unboil one.

When you boil an egg, the heat causes the proteins inside the egg white to tangle and clump together, solidifying it.

New research published in ChemBioChem by scientists at UC Irvine shows how they can essentially reverse the clumping process by adding chemicals to a cooked egg.

"Yes, we have invented a way to unboil a hen egg," UCI biochemist Gregory Weisssaid in a statement. "In our paper, we describe a device for pulling apart tangled proteins and allowing them to refold."

And they didn't just go for a standard 10-minute hard boiled egg. No, the researchers decided, just to make absolutely sure the whites were cooked, to boil the eggs for 20 minutes at 194 degrees Fahrenheit.

Adding urea to the eggs untangled the knotted proteins by chemically breaking them into bits, returning the eggs to a liquid form. (Note: Urea is one of the main ingredients in pee, so these unboiled eggs are probably not delicious.) Then the researcher put the (now liquid) solution into a machine called a 'vortex fluid device.' The device pieces the broken proteins back together within minutes—a vast improvement over older methods of reconstituting proteins, which could take days.

But unboiling eggs isn't the main focus for the researchers. "The real problem is there are lots of cases of gummy proteins that you spend way too much time scraping off your test tubes, and you want some means of recovering that material," Weiss said.

Other researchers from around the world have been looking into the unboiling issue, including researchers from Malta who published research on the same subject last January. The scientists at UC Irvine have filed for a patent of their method, and hope that it will eventually find uses in industries from cheese-making to pharmaceuticals.

This article originally appeared on Popular Science

This article was written by Mary Beth Griggs from Popular Science and was legally licensed through the NewsCred publisher network.

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There's one chemical reaction that, whether you have an interest in chemistry or not, we all carry out on a regular, maybe even daily, basis. That reaction? The Maillard Reaction. This is a process that takes place whenever you cook a range of foods – it's responsible for the flavours in cooked meat, fried onions, roasted coffee, and toasted bread.

The reaction's name is a little deceptive, because it's really an umbrella term for a number of reactions that can produce a complex range of products. The main stages, and some of the different classes of products, are summarised in this graphic.

The Maillard reaction takes its name from French chemist Louis-Camille Maillard, who originally described the reaction between amino acids and sugars in 1912. His study did not offer much in the way of analysis on the reaction's impact on flavour and aroma in cooking, however; it was not until the 1950s that its mechanisms and culinary contributions would become more clearly understood.

In 1973, American chemist John E Hodge published a mechanism for the different steps of the reaction, categorising its stages and identifying a range of the different products produced as a result of these.

He identified the first stage as being the reaction between the sugar and the amino acid; this produced a glycosylamine compound, which in the second step rearranged to produce a ketosamine. The final stage consists of this compound reacting in a number of ways to produce several different compounds, which can themselves react to produce further products.

Melanoidins are one of the potential end products. These are long, polymeric compounds, which act as brown pigments, giving the cooked food its brown colouration. The Maillard reaction is referred to a non-enzymatic browning reaction, as these melanoidins are produced without the aid of enzymes; this differs from enzymatic browning, which is what turns fruits such as avocados brown.

Hundreds of other organic compounds are formed. A subset of these can contribute to the food's flavour and aroma, and some of the different families of these compounds are detailed in the graphic.

As a consequence of the complexity of the Maillard reaction, different amounts of different compounds can be formed in different foodstuffs, giving the wide variety of potential flavours. Cooking conditions can also influence the flavours produced; temperature and pH, amongst other factors, can have an influence.

The products of the Maillard reaction aren't all good news, however. The carcinogenic compound, acrylamide, can also be produced as a result of the reaction, and the levels of it rise as food is heated for a longer period of time.

A 2002 study found that fast food can contain particularly high levels of acrylamide, though measures have since been taken to try and reduce these levels. This gives some perspective to the discussion of carcinogens in food products; whilst, of course, we'd prefer to limit our exposure to these types of chemicals, in many cases carcinogenic compounds are already present as a natural consequence of cooking.

It's not just in your kitchen that the Maillard reaction is taking place. It also occurs at a much slower rate in our bodies, and researchers have suggested that it may have a role in the formation of some types of cataracts. It's also been linked as a contributor to other medical conditions.

Due to its complexity, there's still plenty we don't know about the Maillard reaction. Whilst we know that factors such as pH and temperature can affect the course of the reaction, we still know little about how to adjust these to specifically influence the final products. As we learn more about it, we learn more about the reactions that make cooked foods taste so good – not a bad application of chemistry!

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The germs that call New York City’s subways, parks and waterways home are often a reflection of the people who live there and the events that affect daily life, a new study shows.

“You can see a molecular echo of what’s left behind,” said Christopher Mason, the study’s lead author and a geneticist from Weill Cornell Medical College in New York City.

He and his colleagues used nylon swabs to collect DNA from surfaces in New York City’s subways, subway stations, parks and one waterway. Altogether, they analyzed over 10 billion DNA fragments from their swabs.

The fragments of human DNA found on surfaces in the subway reflected the local population.

“The small traces of human DNA left behind on surfaces serve as a mirror or echo of people who move through that station,” Mason said.

In one station that was flooded during Hurricane Sandy in 2012, they found Mother Nature’s mark: germs linked to marine life and Antarctic environments.

While some may think ignorance is bliss when it comes to knowing what’s living on subway railings and turnstiles, the researchers write in the journal Cell Systems that mapping a major city’s germ profile can be helpful in the future.

The findings, Mason said, "establish the first city baseline of microbial life under our fingertips."

“Now that we have this baseline, you can detect strong changes that may determine if there is anything at all threatening,” such as the spread of a disease or bioterrorism, he said.

For example, the researchers now know there are already traces of DNA that match anthrax and the plague on the subway. Future researchers don’t need to worry if they find the same low levels of those germs in any future investigation into bioterrorism.

“In the case of the plague, we see fragments associated with the plague but not strong evidence of the plague itself,” he said, adding that the same is true for anthrax.

Also, the researchers found, about half of all the germs they analyzed for the study had never been seen before. Mason said that may be because they can’t be grown for analysis.

Despite the unknown germs and the possible connections to anthrax and the plague, the researchers say people shouldn’t be afraid to ride the rails or generally touch surfaces around the city.

Even for people with compromised immune systems, such as those receiving intense cancer treatments, Mason said it’s just another reminder to practice good hygiene.

“The majority really of everything you touch represents a very healthy ecosystem that mirrors what’s on your own skin,” he said.

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The New York World's Fair of 1939-40 was one of the greatest expos the world had ever seen. Visitors to Flushing Meadow Park in Queens were invited to see the "world of tomorrow" giving them a first glimpse of wonders such as the television, the videophone and the Ford Mustang.

It was also the first chance to see nylon, the world's first fully synthetic man-made fibre. It was being sewn into pantyhose by a display of knitting machines as two models played tug of war to demonstrate the strength of the fabric. Nylon had been discovered by the Wallace Carothers' group in DuPont's research division four years earlier. It was introduced at the fair as the new hosiery "wholly fabricated from such common raw materials as coal, water and air" which could be made into filaments "as strong as steel."

Nylon stockings went on to become a huge success, of course, selling 64m pairs for DuPont in their first year alone. Nylon had qualities that were superior to those of the natural product, silk, and it soon found many useful, if sometimes less fashionable, applications. Today it is still used very widely in fabrics, upholstery, sport articles, instrument strings and automotive parts.

Since the dawning of this new era of fully synthetic materials, the advances have been unparallelled in the history of materials. Chemists have discovered new catalysts and developed new synthetic routes to join small molecules into long polymer chains with the right properties for a particular use – the polypropylene fibres that we use in carpets for example, or hard varieties of polyethylene for making plastic bottles.

Physicists, materials scientists and engineers have also designed new processing methods and new technologies to enhance performance to create super-tough substances like kevlar.

Quite rightly, we are becoming more demanding at the same time. We expect products that will further enhance the quality of our lives, but we want materials and technologies that are increasingly energy efficient, sustainable and capable of reducing global pollution. It's a challenge.

Here are five types of polymers that will shape the future.

1. Bioplastics

As we are often reminded, plastics do not degrade and are a very visible source of environmental pollution. To complicate things further, the building blocks of these materials, which we call monomers, are historically derived from crude oil, which is not renewable.

But this is changing. Thanks to innovations with the processes for using enzymes and catalysts, it is becoming increasingly possible to convert renewable resources such as biogas into the major building blocks for manufacturing plastics and synthetic rubbers.

These substances are sustainable because they save fossil resources. But of course this only partly solves the problem. Unless they are also biodegradable, they are still a problem for the environment.

2. Plastic composites/nanocomposites

Plastic composites are the name for plastics which have been reinforced by different fibres to make them stronger or more elastic. For example you can make a polymer stronger by embedding carbon fibres, which creates a lightweight material which is ideal for modern fuel-efficient transport.

These kinds of fibre-reinforced plastics are being increasingly used, particularly in the aerospace industry (the Boeing 787 and the Airbus A360 are 50% composite). Were it not for the high costs, these materials would be used in all vehicles.

More recent additions to the field are nanocomposites, where plastics are instead reinforced with tiny particles of other substances – including graphene. These have any number of potential uses, ranging from lightweight sensors on wind turbine blades to more powerful batteries to internal body scaffolds that speed up the healing process for broken bones.

Nanocomposites will become particularly exciting if we succeed in producing them through processing methods that make it possible to design them in a very controlled manner. If we look at the structures of materials in nature, such as wood, you find they are incredibly complicated and intricate. Our current composites and nanocomposites are very unsophisticated by comparison.

3. Self-healing polymers

No matter how carefully we select materials for engineering applications based on their ability to withstand mechanical stresses and environmental conditions, they will inevitably fail. Ageing, degradation and loss of mechanical integrity due to impact or fatigue are all contributing factors. Not only is this very costly, it can be disastrous, as was the case with the Deepwater Horizon explosion in the Gulf of Mexico in 2010 for instance.

Inspired by biological systems, new materials are being developed which are able to heal in response to what would be traditionally considered irreversible damage. Polymers are not the only materials with the potential for self-healing, but they seem to be very good at it. Within a few years since their first discovery around the turn of the century, many innovative healing systems have been proposed.

What is still incredibly challenging is the idea of extending these concepts to large-volume applications, since self-healing polymers demand much more complicated design than previous generations of polymers. But this seems the ultimate route towards long-lasting, fault-tolerant materials that can be used for products including coatings, electronics and transport.

4. Plastic electronics

Most polymers are insulators and therefore don't conduct electricity. However an upsurge in this field of polymer research emerged in 2000 after the award of a Nobel Prize to Alan MacDiarmid, Alan Heeger and Hideki Shirakawa for work on discovering that a polymer named polyacetylene became conductive when impurities were introduced through a process known as doping.

Not only does the same process make other similar polymers conductive, some can even be converted into light-emitting diodes (LEDs), raising the prospect of flexible computer screens like the one below.

This is an area where polymers still face considerable challenge and strong competition from incumbents like silicon and organic LEDs. Still, when looking for cheap flexible replacements to existing electronic devices, polymers have much to offer as they can be easily processed in solutions and can be 3D-printed.

There seems to be enormous research going on in this area, with polymers sometimes playing the role of the active component, such as in semiconductors, and sometimes acting as a vehicle for other substances, such as in conductive inks.

5. Smart and reactive polymers

Gels and synthetic rubbers can easily adjust their shape in response to external stimuli, which means they are able to respond to changes in their surroundings. The external stimulus would usually be a change in temperature or acidity/alkalinity but it could equally be light, ultrasound or chemical agents. This turns out to be incredibly useful in designing smart materials for sensors, drug delivery devices and many other applications.

You can greatly extend a polymer's natural ability to respond to such stimuli by designing them with this purpose in mind. Mechanophores, for example, are molecular units that can alter the properties of a polymer when they are subjected to mechanical forces. These could have any number of industrial applications, especially if self-healing technology was incorporated too.

Other possibilities for smart polymers include things like window coatings that can wash the windows when they are dirty, and medical stitches that disappear when an injury has healed.

This article was originally published on The Conversation. Read the original article.

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Article:
Yuan, T., Ormonde, C., Kudlacek, S., Kunche, S., Smith, J., Brown, W., Pugliese, K., Olsen, T., Iftikhar, M., Raston, C., & Weiss, G. (2015). Shear-Stress-Mediated Refolding of Proteins from Aggregates and Inclusion Bodies ChemBioChem DOI:10.1002/cbic.201402427

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With Valentine's Day upcoming, part of your Valentine's plan may well involve sending flowers. These come in an array of different colours, and also have a range of different scents. What are the chemical compounds behind these scents? That's the question that this graphic tries to answer, with a more detailed discussion of each below.

Firstly, it's important to realise that aroma chemistry is complex, and the smell of any flower is never really the consequence of a single chemical compound. Flowers give off a complex mix of volatile organic chemicals, and whilst not all of these will contribute to the aroma, a significant number will impact it to varying degrees. Whilst we can't point to single compounds as being the cause of flowers' scents, we can identify those that have a major impact on the aroma that our noses detect; in many cases, there will be molecules that make a large contribution, and it's those we'll discuss here.

Roses

Roses are by far and away the most popular choice of flower for Valentine's Day – and by association, the most expensive! Their scent is majorly influenced by compound named after the flower, (-)-cis-rose oxide. This molecule is a particular isomer of rose oxide (which has 4 different isomers), and the one which contributes the typical floral rose fragrance. It's detectable by our noses at very low concentrations in air – down as low as 5 parts per billion. To give this some perspective, one part per billion is equivalent to one second in thirty-two years.

Another compound that contributes to the scent of roses is beta-damascenone. This compound belongs to a family of chemical entities known as rose ketones. It also has an even lower odour threshold than rose oxide, with its aroma being detectable at just 0.009 parts per billion. Another compound with a comparably low odour threshold, beta-ionone, is also an important contributor; both of these compounds are minor constituents of the plant's essential oil, but of great importance to its perceived fragrance.

Other compounds that make minor contributions to the aroma include geraniol, nerol, (-)-citronellol, farnesol, and linalool.

Carnations

Carnations, too, are a common component of floral bouquets. In comparison to roses, their scent is much fainter; the major aroma chemicals that make up this scent are eugenol, beta-caryophyllene, and benzoic acid derivatives.

Scents can be very variable between different species of carnations; one study correlated this with the varying proportions of eugenol and methyl salicylate in the aroma volatiles. Eugenol is actually a compound that's been discussed before on the site, in the context of its occurrence in cloves. Methyl salicylate is also found in many other plants, and is more commonly known as oil of wintergreen.

Violets

Violets are perhaps less common in bouquets than roses and carnations, but perhaps much more interesting from an aroma perspective. Their scent is primarily caused by the presence of compounds called ionones, of which there are a range of forms with subtly different structures. On the face of it, this might not seem that interesting – but these ionones have a peculiar interaction with our olfactory receptors.

We become accustomed to most persistent smells, as our brain registers them as constants and phases them out. This is why you can get used to the smell of a perfume, to the extent that you no longer notice it. This is where the ionones in violets' aroma differ. They essentially short-circuit our sense of smell, binding to the receptors and temporarily desensitising them. As this shut-down is only temporary, the ionones can soon be detected again, and are registered as a new smell. Consequently, the scent of the violet appears to disappear – then reappear!

Lilies

Lilies are flowers more commonly associated with funerals in some countries. Their composition is varied across different species, but across the genus (E)-beta-ocimene and linalool are major components of the aroma. Lilies aren't particularly unique in producing linalool – in fact, it's produced by over 200 other species of plants. A large number of personal hygiene products include the compound as a perfume, and it's also found in perfumes themselves.

Other aroma-contributing compounds in lilies include myrcene, a compound also found in hops used to brew beers. Additionally, some varieties of lily contain eucalyptol (also referred to as 1,8-cineole), so called because it's also a major component of the essential oil of the eucalyptus tree.

Hyacinth

Three compounds are particular contributors to the scent of hyacinth. Ocimenol has a scent described as fresh and citrusy, whilst cinnamyl alcohol has a balsamic odour – its name is derived from the fact that it also occurs in cinnamon. Another compound, ethyl 2-methoxybenzoate, adds a floral, fruity aspect to the scent.

Chrysanthemums

Again, the variability between members of the chrysanthemum genus is considerable. Terpene compounds such as alpha-pinene, eucalyptol, camphor, and borneol have all been found in varying quantities in different species.

Alpha-pinene is another molecule discussed previously on the site, in the context of its contribution to the aroma of Christmas trees. Compounds named after chrysanthemums themselves are also present; chrysanthenone and chrysanthenyl acetate are both contributors.

Beta-caryophyllene has also been detected in some varieties.

Lilacs

Lilacs are another flower which lend their name to the chemical compounds that their aroma contains. Whilst (E)-beta-ocimene is the major component of their fragrance, it is also contributed to by lilac aldehyde and lilac alcohol. Like rose oxide, both of these compounds have a number of different isomers, with varying impacts on the overall scent of the flowers. Benzyl methyl ether also has a significant impact on their scent when they are in full bloom, contributing a fruity odour.

Other Flowers

There are, of course, numerous other varieties of flowers which aren't featured here. In an attempt to pre-empt the "what about [insert flower name here]?" queries, it's worth pointing out that the research available on the aromas of some flowers is quite sparse. In particular, it would have been great to include tulips in the graphic, but information on their aroma composition was hard to come by!

It's also worth reiterating that this graphic is merely meant to provide a general representation. There's a lot a variation in the precise concentration of chemicals between different species, so this is really only intended as a rough guide. There are some species of rose, for instance, which have little or no aroma to speak of! This just serves to emphasise the fact that aroma chemistry can be quite complex (but fascinating) stuff.

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Whether you're a coffee connoisseur or completely unfussy about the manner in which you get your caffeine fix, there's no denying that the smell of freshly-brewed coffee in the morning is an invigorating one.

The chemistry behind this aroma, though, is far from simple; a complex collection of chemical compounds are responsible, and this graphic takes a look at a selection of these.

We've taken a look at chemical compounds found in coffee beans previously, but then we were primarily concerned with what causes the bitter notes in the flavour of coffee, as well as looking at some of the more obvious compounds present, such as caffeine. Generally, the majority of the molecules mentioned in that post aren't big players when it comes to coffee's aroma.

Kick-starting your day with caffeine might be the goal of the morning coffee, but caffeine itself is odourless as well as tasteless, and instead it's a range of other compounds that contribute to the scent.

Specifically, we're talking volatile compounds – organic compounds that easily evaporate at room temperature and pressure. Compounds have to be airborne in order for our nose to be able to detect their smell, so it follows that any compounds that are particularly large (for example, the melanoidins that contribute to coffee's colouration) will have low volatilities, and won't contribute to the aroma. That leaves us with the slightly more modestly-sized molecules shown in the graphic. But where do these come from?

There are a number of different ways in which coffee's aroma compounds are created, but they're all commonly produced as a consequence of the roasting process. The Maillard reaction, the complexities of which were discussed on the site recently, is a big contributor here, the reaction between proteins and sugars in the coffee beans producing a range of products. In addition to this, degradation and decomposition of other compounds in the coffee beans can also produce aroma compounds.

The brewing part of the coffee-making process isn't about chemical change – rather, it's about extracting compounds from the roasted coffee beans. How well different molecules can be extracted depends on their solubilities, which in turn depends on a property known as polarity. Different types of atoms exert more of a 'pull' on the electrons in chemical bonds than others; oxygen exerts more of a pull on bonding electrons than carbon, for instance. A bond between a carbon and oxygen atom is what we would refer to as a polar bond, as the bonding electrons are pulled closer to the oxygen atom, giving it a slight negative charge.

The presence of polar bonds in a molecule can lead to the molecule being polar as a whole if the polar bonds are not distributed evenly. This results in the different ends of the molecule becoming slightly charged. Going back to our discussion of solubilities, polar molecules are more soluble in water than non-polar molecules. This is because water itself is a polar molecule – the oxygen atom exerts more of a pull on bonding electrons than the hydrogen atoms – and interacts with and surrounds other polar molecules, allowing them to dissolve. So, the more polar molecules in coffee beans are extracted in higher percentages during the brewing process than the non-polar molecules.

A whole range of studies have been dedicated to discerning which of these extracted compounds contribute to the aroma of a cup of coffee. Whilst over a thousand different chemical entities have been identified in coffee beans, and a significant number of these will be extracted during brewing, it's a comparatively small subset of chemicals that impact on the aroma. The studies often consider two main factors when discerning a compounds' aroma impact: the concentration of the compound, and the compound's odour threshold, or the minimum concentration at which we can detect its smell. The ratio of a compound's concentration to its odour threshold gives the compounds 'odour activity value' (OAV), which gauges its importance to the overall aroma.

A number of families of compounds are significant contributors to coffee's aroma. Several sulfur-containing compounds are of importance, including 2-furfurylthiol, with an aroma that on its own is actually commonly described as 'roasted coffee'. There are also some compounds which on their own might smell pretty unpleasant, but in chorus with the other compounds add nuances to the aroma; for example methanethiol, which has a smell described as like that of rotten cabbage, and which is also a significant contributor to the smell of flatulence. Another sulfur-containing compound, 3-mercapto-3-methylbutyl formate, is brilliantly described as having a 'catty' odour in isolation.

Other contributing families of compounds in include aldehydes, which generally add a fruity, green aroma, furans, which contribute caramel-like odours, and pyrazines, which have an earthy scent. Guaiacol and related phenolic compounds offer smoky, spicy tones, and pyrroles and thiophenes are also present in low concentrations.

As it happens, coffee's aroma might even have a little more to it. A 2008 study found that the smell of coffee beans affected gene and protein activity in rat brains, some of which were linked to stress relief. Whilst rat brains and human brains have their differences, it might suggest that the lift from your morning coffee isn't solely the consequence of its caffeine content!

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Trying to impress a special someone, a group of friends, or a team of colleagues by inviting them over for a delicious dinner can be a great way to show off your cooking skills but can also be incredibly stressful — even if you know what you're doing.

Timing everything down to the right minute so that the food on your guests' plate is cooked through, the right temperature upon serving, and looks beautiful on the plate is a daunting task and difficult to pull off.

Then there's your own appearance to think of, and if you're planning on cutting a lot of onions, then good luck looking like you didn't just finish watching the tear-wrenching film Old Yeller.

Here are four techniques, provided by the American Chemical Society's Reactions YouTube series, that can help you on your descent into kitchen-cooking hell. There's also some cool science behind these techniques that are sure to impress any dinner guest as they happily chow down.

1. Preserve the bright-green color of your cooked vegetables.

Chlorophyll A and B are the two molecules that give vegetables their beautiful, bright-green color. When you cook the vegetables for a long period of time, the heat breaks down the plant cells in your veggies. As a result, the cells release acids.

Normally, these acids are kept separate from the chlorophyll, but when heated, the acids escape from the plant cells and come into contact with the green molecules. When this happens, the acids change the chlorophyll molecules' chemical composition, which, in turn, changes the color of your vegetables from a delicious-looking vibrant green to an unappealing dark green.

To prevent this from happening, cook your vegetables for approximately seven minutes. This is long enough to cook them through but not so long that the acids get the chance to do their dirty work.

2. Don't cry over your onions. Refrigerate them!

Onions are a delicious addition to any guacamole, burrito, stir fry, or casserole. But they come with a price: Your tears.

Every time you cut into an onion, you release compounds called sulfenic acids. One of these sulfenic acids mixes with other enzymes in the onion that you release during cutting. This mixture is what then creates the eye-burning, tear-inducing gas, called syn-propanethial-S-oxide.

The gas wafts toward your eyes and upon contact stimulates your sensory neurons. The neurons then send signals to your brain that tells you your eyes are burning, and your body's immediate response to alleviate the pain is to wash it away with tears.

To protect your eyes, refrigerate your onions for at least 30 minutes before chop time. This reduces the onion's tendency to release sulfenic acid. Another option is to cut the onion under water, that way the water, and not your eyes, absorbs the acid.

3. Don't cook with a bad, stinky egg.

Rotten eggs not only taste gross but their putrid state gives them a fetid smell that will have any guest running for the hills instead of flocking to the dinner table. The reason eggs go bad in the first place is because of the many tiny dimples, shown in the image above, that dot their shells.

These dimples are actually pores that allow air to flow in and out of the shell so the developing chick within can breathe. But, the pores also let bacteria in, which feast on the gelatinous embryo inside breaking down proteins and emitting the putrid-scented gas called hydrogen sulphide.

Over time, the gas builds up inside of the egg. To protect your kitchen from a smelly egg, place the egg inside of a glass of water. If the egg is filled with hydrogen sulphide, it will float to the surface. If the egg sinks, then you and your guest's noses are safe.

Hosting a dinner will test you on many levels, and if all else fails, there's always pizza delivery.

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Of all the chemical reactions we've covered within the past few months, the one filmed below probably takes the prize for coolest looking and possibly scariest. After the pile of reactants is lit, it begins to look like tentacles are crawling out of a portal to Hell.

In reality, what's depicted in the video below is actually two reactions: the decomposition of ammonium dichromate and the combustion reaction of mercury (II) thiocyanate.

The orange powder is ammonium dichromate and when heat is introduced, it forms nitrogen gas, water, and ammonium (III) oxide, which is the dark powder that looks like the volcano you see.

What appears to be tentacles is actually what happens when heat is introduced to mercury (II) thiocyanate. The white solid expands when it's heated to become a dark, tentacle-like mass due to its decomposition to carbon nitride. In addition, sulfur dioxide and mercury (II) sulfide are also produced. The reaction is appropriately nicknamed the "Pharoah's Serpent" and was sold in stores as fireworks until people realized it's toxic.

Check out the video below:

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When I was a kid, my parents had a collection of historic old, yellowed newspapers. For example, I distinctly remember an old Washington Post newspaper sitting on a bookshelf from July 21, 1969 with the headline “The Eagle Has Landed – Two Men Walk on the Moon.”

Or a fading, brownish-yellow one from August 8, 1974 with the big headline, “Nixon Resigns.”

These newspapers are fascinating artifacts documenting history, from remarkable moments to the relatively mundane. Unfortunately, they were also hard to read due to the yellowed, brown color and fading print. So why do old newspapers – and books – turn yellow? And is there any way to prevent this from happening?

It is generally thought that paper was invented around 100 BC in China. Originally made from wet hemp that was, then, beaten to a pulp, tree bark, bamboo, and other plant fibers were eventually used. Paper soon spread across Asia, first only being used for official and important documents, but as the process became more efficient and cheaper, it became far more common.

Paper first arrived in Europe likely around the 11th century. Historians believe the oldest known paper document from the “Christian West” is the Missal of Silos from Spain, which is essentially a book containing texts to be read during Mass. This paper was made out of a form of linen. While paper, books, and printing would evolve throughout the next eight hundred years, with the Gutenberg printing press coming in the mid-15th century, paper was normally made out of linen, rags, cotton, or other plant fibers. It wouldn’t be until the mid-19th century when paper was made out of wood fiber.

So what changed? In 1844, two individuals invented the wood paper-making process. On one end of the Atlantic Ocean was Canadian inventor Charles Fenerty. Growing up, his family owned a series of lumber mills in Nova Scotia. Knowing the durability, cheapness, and availability of wood, he realized it could be a good substitute for the much more expensive cotton used in paper. He experimented with wood pulp and on October 26, 1844, he sent his wood pulp paper to Halifax’s top newspaper, The Acadian Recorder, with a note touting the durability and cost-effective spruce wood paper. Within weeks, the Recorder used Fenerty’s wood pulp paper.

At the same time, German binder and weaver Friedrich Gottlob Keller was working on a wood-cutting machine when he discovered the same thing as Fenerty – that wood pulp could act as a cheaper paper than cotton. He produced a sample and, in 1845, received a German patent for it. In fact, some historians credit Keller for the invention more than Fenerty simply due to the fact that he received a patent and the Canadian did not.

Within thirty years, wood pulp paper was all the rage on both sides of the pond. While wood pulp paper was cheaper and just as durable as cotton or other linen papers, there were drawbacks. Most significantly, wood pulp paper is much more prone to being effected by oxygen and sunlight.

Wood is primarily made up of two polymer substances – cellulose and lignin. Cellulose is the most abundant organic material in nature. It is also technically colorless and reflects light extremely well rather than absorbs it (which makes it opaque); therefore humans see cellulose as white. However, cellulose is also somewhat susceptible to oxidation, although not nearly as much as lignin. Oxidation causes a loss of electron(s) and weakens the material. In the case of cellulose, this can result in some light being absorbed, making the material (in this case, wood pulp) appear duller and less white (some describe it as “warmer”), but this isn’t what causes the bulk of the yellowing in aged paper.

Lignin is the other prominent substance found in paper, newspaper in particular. Lignin is a compound found in wood that actually makes the wood stronger and harder. In fact, according to Dr. Hou-Min Chang of N.C. State University in Raleigh, “Without lignin, a tree could only grow to about 6 ft. tall.” Essentially, lignin functions as something of a “glue,” more firmly binding the cellulose fibers, helping make the tree much stiffer and able to stand taller than they otherwise would, as well able to withstand external pressures like wind.

Lignin is a dark color naturally (think brown-paper bags or brown cardboard boxes, where much of the lignin is left in for added strength, while also resulting in the bags/boxes being cheaper due to less processing needed in their creation). Lignin is also highly susceptible to oxidation. Exposure to oxygen (especially when combined with sunlight) alters the molecular structure of lignin, causing a change in how the compound absorbs and reflects light, resulting in the substance containing oxidized lignin turning a yellow-brown color in the human visual spectrum.

Since the paper used in newspapers tends to be made with a less intensive and more cost-efficient process (since a lot of the wood pulp paper is needed), there tends to be significantly more lignin in newspapers than in, say, paper made for books, where a bleaching process is used to remove much of the lignin. The net result is that, as newspapers get older and are exposed to more oxygen, they turn a yellowish-brown color relatively quickly.

As for books, since the paper used tends to be higher grade (among other things, meaning more lignin is removed along with a much more intensive bleaching process), the discolorization doesn’t happen as quickly. However, the chemicals used in the bleaching process to make white paper can result in the cellulose being more susceptible to oxidation than it would otherwise be, contributing slightly to the discolorization of the pages in the long run.

Today, to combat this, many important documents are now written on acid-free paper with a limited amount of lignin, to prevent it from deteriorating as quickly.

As for old historic documents – or my parent’s old newspapers – there may not be a way to reverse the damage already done, but one can prevent further damage. It is important to store the documents or newspaper in a cool, dry, dark place, just like how museums store historic documents in a temperature-controlled room with low-lighting. Additionally, do not store them in an attic or basement; those places can get humid and can have significant temperature swings. If one would like to display the newspaper or document out in the open, put it behind UV protected glass to deflect harmful rays. Most importantly, limit the handling of said document or newspaper – nothing destroys a valuable piece of paper like frequent handling.

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NOW WATCH: A 1,100-Ft Wide Asteroid And Its Orbiting Moon Just Zoomed Past Earth

It may look like nothing more than a small ball of metal, but the shape-shifting and self-propulsion abilities of a liquid metal alloy discovered by scientists at China's Tsinghua University has captured the imaginations of scientists and science-fiction fans across the world.

Professor Liu Jing and his team have created what they believe could prove the first step toward developing a robot similar to the infamous T-1000 shape-shifting, liquid metal assassin from the Terminator movies.

"The soft machine looks rather intelligent and [can] deform itself according to the space it voyages in, just like [the] Terminator does from the science-fiction film,"professor Liu told New Scientist.

The device is made from a drop of metal alloy consisting mostly of gallium, which is a liquid at just under 30 degrees Celsius. Last year they discovered that an applied electrical current causes the gallium alloy to drastically alter its shape. Changing the voltage applied to the metal allowed it to 'shape-shift' into different formations. When the current was switched off, the metal returned to its original drop shape. 

But the team made their biggest breakthrough when they realized that bringing it into contact with a flake of aluminum caused a reaction creating hydrogen bubbles that allowed it to move of its own accord. Liu said it was able to 'fuel' itself for about an hour.

Here is what the process looks like:

Aluminum merges with the droplet of mostly gallium:

The reaction creates bubbles that help  propel the droplet forward:

When electric volts are added the droplet changes shape. When the electricity is removed, the material reverts back into its original form:

"The machine has two processes. One is to create gases like hydrogen. Part of these gases form the propulsion. There's also something important, in fact very important, which is the electricity generated behind the alloy. So this galvanic battery creates an internal electrical power, and this type of electricity will very easily lead to stretching of the surface of the liquid metal in an asymmetrical pattern, and this pattern leads to rotations inside the liquid metal, and the process of these rotations will set the liquid metal in motion in a certain direction," he said.

While the scientists are still learning more about the properties of the metal, Liu believes it could have a variety of medical applications, for example delivering medicine in blood vessels. 

"At present it has potential to become a robot, but a robot for the veins. So apart from a robot for the veins it could for example [be used in] people's windpipes and digestive system, it may perhaps be able to carry out some medical tasks, for example transporting some medicines," he said, adding that scientists would of course first have to ensure that there would be no side-effects to ingesting the metal.

As for comparisons to the deadly machine in the Terminator movies, Liu said that while the thought of his discovery bearing resemblance to the T-1000 did make him chuckle, he hoped that his robot would work for the good of mankind.

"Perhaps people think it's like the Terminator but I think to a certain extent the Terminator's not very good, he wasn't good for mankind. So we hope that if in the future we can really make a soft robot, we hope that it can be a more human-like robot," he said.

Here's a video of the process:

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NOW WATCH: Animated map of what Earth would look like if all the ice melted

For the first time, scientists have confirmed what they have long suspected: Complex organic molecules exist in the disks from which planets form.

While it is a big step from these observed molecules to living things, the discovery demonstrates that at least some planets form with the essential elements of life already present.

The observation of the star MWC 480, reported in Nature, was made using the Atacama Large Millimeter/submillimeter Array (ALMA). Barely a million years old, MWC 480 is surrounded by a disk from which planets are expected to be born.

In the outer reaches of the disk, ALMA picked up the spectral signatures of methyl cyanide (CH3CN), cyanoacetalyne (HC3N) and hydrogen cyanide (HCN) signatures. The distance from MWC 480 indicated to the observing team that these molecules are in the region that will one day become MWC's Kuiper Belt, leading to cyanides becoming incorporated into comets.

"Studies of comets and asteroids show that the solar nebula that spawned the Sun and planets was rich in water and complex organic compounds," noted lead author Dr. Karin Öberg, an astronomer with the Harvard-Smithsonian Center for Astrophysics.

"We now have even better evidence that this same chemistry exists elsewhere in the Universe, in regions that could form solar systems not unlike our own."

The concentrations observed are similar (0.01%) to those seen in the comets of our own solar system. This is despite the fact that MWC 480 is no solar twin, having a mass 1.8 times that of the sun. The disk is 10 times the mass of the one required to form the solar system and 2-3 times warmer.

Complex molecules have been detected beyond the solar system before. However, these have been in colder and more stable environments than the protoplanetary disk, raising the question of whether any such molecules could survive proximity to a forming star.

Curiously, methyl cyanide appears to have multiplied or become concentrated in the process. The concentration is higher than in the interstellar clouds where complex molecules have been observed before. Indeed, there is more methyl cyanide orbiting MWC 480 than there is water in the Earth's oceans.

The outer edge of MWC 480's disk is too cold to support life, and probably always will be. However, comets from the outer solar system are thought to have brought water to Earth, and future planets in MWC 480's habitable zone may find themselves seeded with complex organic molecules as well.

"From the study of exoplanets, we know the Solar System isn't unique in its number of planets or abundance of water," concluded Öberg. "Now we know we're not unique in organic chemistry. Once more, we have learnt that we're not special. From a life in the Universe point of view, this is great news."

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NOW WATCH: Scientists Have A Pretty Good Idea What Aliens May Actually Look Like

An atomic clock that sets the time by the teensy oscillations of strontium atoms has gotten so precise and stable that it will neither gain nor lose a second for the next 15 billion years.

The strontium clock, which is about three times as precise as the previous record holder, now has the power to reveal tiny shifts in time predicted by Einstein's theory of relativity, which states that time ticks faster at different elevations on Earth.

That precision could help scientists create ultradetailed maps of the shape of the Earth.

"Our performance means that we can measure the gravitational shift when you raise the clock just 2 centimeters [0.79 inches] on the Earth's surface," study co-author Jun Ye, a physicist at JILA, a joint institute of the National Institute of Standards and Technology and the University of Colorado, Boulder, said in a statement.

The team also improved how closely the ticks matched one another, a metric called its stability, by almost 50 percent. 

Insane precision

Atomic clocks typically work by measuring the vibrational frequency of atoms, such as strontium or cesium, as the atoms jump between different energy levels.

Every atom naturally oscillates at very high frequencies billions or trillions of times per second. Counting these regular beats provides a highly precise measure of time. Currently, a cesium clock at NIST defines the second, where 1 second is 9,192,631,770 oscillations of the cesium atom.

In the new clock, thousands of strontium atoms at extremely cold temperatures are essentially pinned into a narrow column by intense laser light. To measure time, the clock hits those atoms with just the right frequency of red laser light to make the atoms jump energy levels. The previous version of the clock used a similar technique.

On this occasion, however, the researchers improved the design by eliminating measurement errors related to an external source of electromagnetic radiation known as blackbody radiation, which is given off by opaque objects held at constant temperatures.

The team placed radiation shields around the device, as well as platinum thermometers inside the clock's vacuum tube, to better account for the extra heat. The researchers also improved their calculations of how much radiation would be generated.

The new clock can also be operated at room temperature, as opposed to the cryogenic temperatures used in past versions.

"This is actually one of the strongest points of our approach, in that we can operate the clock in a simple and normal configuration while keeping the blackbody radiation shift uncertainty at a minimum." Ye said. (Blackbody radiation can affect the atom's energy level, which then affects the tick rate.)

The new record holder won't lose a second over the current age of the universe. But strontium atoms beat at 430 trillion times per second, so theoretically, at least, there's room for more improvement.

Relativistic measurements

The new clock is so precise that it can detect relativity in action at incredibly small scales. In a concept known as gravitational time dilation, time passes more quickly in weaker gravitational fields, so the higher the altitude on Earth, the lower the gravity is there — and the faster time is passing. The current clock is so sensitive that it could detect these effects with elevation changes as little as that caused by putting a small book under the clock.

If the clock can improve further, that would enable more detailed measurements of the Earth's shape. Currently, instruments like tidal gauges and gravimeters perform this task.

The findings were published April 21 in the journal Nature Communications.

Follow Tia Ghose on Twitter and Google+.Follow Live Science @livescience, Facebook& Google+. Originally published on Live Science.

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NOW WATCH: Here's what astronauts actually see when they go out for a walk in space

Terrifying headlines about synthetic drugs like "bath salts" or those with names like "flakka" that turn people into"naked, paranoid lunatics" make it sound like you'd have to be a raving lunatic to use a synthetic drug.

But synthetic or designer drug usage — including research chemicals, substances chemically tweaked so they are legal instead of illegal (like flakka), and some varieties of fake marijuana — is way too common to be considered just a raving lunatic sort of thing.

According to the 2014 Global Drugs Survey, approximately 10% of citizens from countries with more than 1,500 survey respondents (including the US, Australia, Hungary, Germany, and several other European countries) used synthetic drugs within the past year. In the US, that number is about 20% — one in five people used some form of synthetic drug in the last year.

Because the survey is a voluntary opt-in (organized by media partners like The Guardian), these numbers might be slightly higher than for the general population, but there's plenty of evidence that synthetic drug use is skyrocketing. In the first few months of 2015, US poison control centers reported four times as many reports of bad drug reactions from synthetics than in all of 2014. The Guardian reports that we've seen an "unprecedented increase" in the types and availability of these drugs, according to the European Monitoring Centre for Drugs and Drug Addiction.

So what makes these drugs so popular?

Perhaps the main reason is that many of them are technically legal. By changing just a couple of molecules that make up a drug, a chemist can create something that's distinct from an illegal drug, making it easier to sell or buy it. Even though it's illegal to make something clearly similar to illegal drugs for consumption, they can slap a "not for human consumption" label on there, at which point they are just creating a chemically unique substance that happens to be similar to something people use to get high.

Not only are they technically legal, they're also cheap and easy to get. Synthetic marijuana and bath salts can be bought in head shops for cheap prices — $5 to $25, depending on variety and dose — or from online stores, where a quick search reveals bath salts "on sale" for $15.

Online dealers — since even in the post-Silk Road era, new web bazaars pop up selling drugs all the time — can order whatever chemical formulation is popular at the time, usually from labs in China. In other cases, they can even design their own formula, like Matter journalist Mike Power did (with the help of a chemist) just to see how easy it was to order a designer drug himself, tweaking the molecules on a type of speed popular in the 1960s.

But as Nicola Davison explains in The Guardian, "this tiniest molecular tweak" that makes a drug legal "can create a drug with dramatically different psychoactive effects."

Chemist Andrew Westwell told Power that it's reasonable to predict fairly similar psychoactive properties for a chemically similar substances. But, he said, the slightest tweak can also cause unexpected variations. As he explains, "It is notoriously difficult to predict how a drug structure modification will affect potency, activity, or toxicology. If we could make these types of predictions with any degree of certainty, fiendishly difficult areas like drug discovery and drug development would become so much more straightforward."

Essentially, laws can't keep up with chemistry. The number of molecular changes that can be made to a substance is almost infinite. Shut down a market for a drug or prevent people from using it in some way — some people on parole smoke synthetic pot because it's less likely to show up in a drug test than marijuana — and people will opt for something else, even if that thing is more dangerous and has more unpredictable side effects.

"Instead of constricting supply, drug laws focused on a group of well-known chemicals have simply pushed users towards new and increasingly dangerous forms of chemical stimulation," Power writes in Matter. "And now attempts to enforce the law simply encourage greater, riskier innovation — and no one now knows where that will take us."

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NOW WATCH: How to supercharge your iPhone in only 5 minutes

Did you know that the discovery of a way to make ammonia was the single most important reason for the world's population explosion from 1.6 billion in 1900 to 7 billion today? Or that polythene, the world's most common plastic, was accidentally invented twice?

The chances are you didn't, as chemistry tends to get overlooked compared to the other sciences. Not a single chemist made it into Science magazine's Top 50 Science stars on Twitter. Chemistry news just don't get the same coverage as the physics projects, even when the project was all about landing a chemistry lab on a comet.

So the Royal Society of Chemistry decided to look into what people really think of chemistry, chemists and chemicals. It turns out most people just don't have a good idea of what it is chemists do, or how chemistry contributes to the modern world.

This is a real shame, because the world as we know it wouldn't exist without chemistry. Here's my top five chemistry inventions that make the world you live in.

1. Penicillin

There's a good chance that penicillin has saved your life. Without it, a prick from a thorn or sore throat can easily turn fatal. Alexander Fleming generally gets the credit for penicillin when, in 1928, he famously observed how a mould growing on his petri dishes suppressed the growth of nearby bacteria. But, despite his best efforts, he failed to extract any usable penicillin. Fleming gave up and the story of penicillin took a 10-year hiatus. Until in 1939 it took Australian pharmacologist Howard Florey and his team of chemists to figure out a way of purifying penicillin in useable quantities.

However, as World War II was raging at the time, scientific equipment was in short supply. The team therefore cobbled together a totally functional penicillin production plant from from bath tubs, milk churns and book shelves. Not surprisingly the media were extremely excited about this new wonder drug, but Florey and his colleagues were rather shy of publicity. Instead Fleming took the limelight.

Full-scale production of penicillin took off in 1944 when the chemical engineer Margaret Hutchinson Rousseau took Florey's Heath Robinson-esque design and converted it into a full-scale production plant.

2. The Haber-Bosch process

Nitrogen plays a critical role in the biochemistry of every living thing. It is also the most common gas in our atmosphere. But nitrogen gas doesn't like reacting with very much, which means that plants and animals can't extract it from the air. Consequently a major limiting factor in agriculture has been the availability of nitrogen.

In 1910, German chemists Fritz Haber and Carl Bosch changed all this when they combined atmospheric nitrogen and hydrogen into ammonia. This in turn can be used as crop fertiliser, eventually filtering up the food chain to us.

Today about 80% of the nitrogen in our bodies comes from the Haber-Bosch process, making this single chemical reaction probably the most important factor in the population explosion of the past 100 years.

3. Polythene – the accidental invention

Most common plastic objects, from water pipes to food packaging and hardhats, are forms of polythene. The 80m tonnes of the stuff that is made each year is the result of two accidental discoveries.

The first occurred in 1898 when German chemist Hans von Pechmann, while investigating something quite different, noticed a waxy substance at the bottom of his tubes. Along with his colleagues he investigated and discovered that it was made up of very long molecular chains which they termed polymethylene. The method they used to make their plastic wasn't particularly practical, so much like the penicillin story, no progress was made for some considerable time.

Then in 1933 an entirely different method for making the plastic was discovered by chemists at, the now defunct chemical company, ICI. They were working on high-pressure reactions and noticed the same waxy substance as von Pechmann. At first they failed to reproduce the effect until they noticed that in the original reaction oxygen had leaked into the system. Two years later ICI had turned this serendipitous discovery into a practical method for producing the common plastic that's almost certainly within easy reach of you now.

4. The Pill and the Mexican yam

In the 1930s physicians understood the potential for hormone-based therapies to treat cancers, menstrual disorders and of course, for contraception. But research and treatments were held back by massively time-consuming and inefficient methods for synthesising hormones. Back then progesterone cost the equivalent (in today's prices) of $1,000 per gram while now the same amount can be bought for just a few dollars. Russel Marker, a professor of organic chemistry at Pennsylvania State University, slashed the costs of producing progesterone by discovering a simple shortcut in the synthetic pathway. He went scavenging for plants with progesterone-like molecules and stumbled upon a Mexican yam. From this root vegetable he isolated a compound that took one simple step to convert into progesterone for the first contraceptive pill.

5. The screen you are reading on

Incredibly, plans for a flat-screen colour displays date back to the late 1960s! When the British Ministry of Defence decided it wanted flat-screens to replace bulky and expensive cathode ray tubes in its military vehicles. It settled on an idea based on liquid crystals. It was already known that liquid crystal displays (LCDs) were possible, the problem was that they only really worked at high temperatures. So not much good unless you are sitting in an oven.

In 1970 the MoD commissioned George Gray at the University of Hull to work on a way to make LCDs function at more pleasant (and useful) temperatures. He did just that when he invented a molecule known as 5CB). By the late 1970s and early 1980s, 90% of the LCD devices in the world contained 5CB and you'll still find it in the likes of cheap watches and calculator. Meanwhile derivates of 5CB make the phones, computers and TVs possible.

Mark Lorch is Senior Lecturer in Biological Chemistry at University of Hull. He tweets as @sci_ents .

This article was originally published on The Conversation. Read the original article.

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NOW WATCH: Here's What Happens To Your Brain On Caffeine

Aspartame is the artificial sweetener that people love to hate.

It's also one of the most common alternatives to sugar, found in over 6,000 products and sold as NutraSweet® and Equal®.

The same amount of aspartame and sugar has the same number of calories as sugar, but since aspartame is 200 times sweeter than sugar it goes a lot farther.

Because of this, aspartame often used in diet sodas to cut down on calories. But in April 2015 PepsiCo announced that it will no longer use aspartame in Diet Pepsi, amid popular concern that aspartame causes cancer and other health problems.

Do these claims actually hold water? In its Reactions video series, the American Chemical Society put the rumors to scientific scrutiny.

The concern about aspartame causing cancer comes from the fact that your body breaks it down into formaldehyde, which is a substance known to cause cancer under long term exposure.

It's worth noting that there's an inconsistency here: 12 oz. of fruit juice can put up to 5 times more formaldehyde into your body than the same amount of diet soda, yet no one is concerned about fruit juice causing cancer.

And there's no reason to be concerned about the formaldehyde from fruit juice, either. Formaldehyde is used pretty much immediately in the body to make amino acids, the components that make up proteins — it doesn't get stored and build up to potentially harmful levels. What's not used to in the process of making proteins is turned into formic acid, which is then excreted in urine or broken down by carbon dioxide and water.

Studies back up this argument that aspartame is safe.

One study compared vital signs, lab tests, and symptoms of a group of people who took pills with the amount of aspartame in 10 liters of diet soda per day for 24 weeks with a group that took a placebo pill. The scientists found no differences between the two groups, even at that extremely high daily dose of aspartame.

No link has been found between aspartame and cancer, and people have been looking: aspartame is one of the most heavily researched food additives of all time since the FDA approved it for human consumption in the early 80s.

Besides the concerns about cancer, some people have claimed reactions to aspartame including headaches, seizures, nausea, anxiety, and depression. To test this, scientists ran a study in which people who claimed to have reactions to aspartame were given snack bars with the sweetener or control snack bars that didn't contain aspartame. Again, there was no difference between the two groups, and zero evidence of an acute response to aspartame.

Aspartame is only really a concern for people with phenylketonuria, a condition with makes them unable to break down phenylalanine, another byproduct of aspartame in the body. If phenylalanine accumulates in the body, it can cause brain damage. But anyone who metabolizes phenylalanine normally doesn't need to worry.

Despite the hype they get, claims about dangers of aspartame are from "anecdotal evidence or flawed studies," the video says. So enjoy that diet soda, in moderation.

Watch the whole video from the American Chemical Society:

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Most people know the smell. That wet-dog smell.

The smell that wafts off a dog after they go for a swim or bath. It's not particularly pleasant.

A recent video from the American Chemical Society explains just how the chemistry behind this unique smell works.

First a primer on smell, from Wired's Nick Stockton:

When you inhale, microscopic airborne molecules alight upon specialized cells — called olfactory sensory neurons — deep in your nasal cavity. These cells translate the chemical signature from the molecules into an electrical signal, which gets sent along to your brain. There, it triggers the circuits that help you put a label to the smell: Bacon! New Book! Wet dog!

As for where those smells come from? Well, it turns out that it's not really the dog itself that smells, but excretions from the microorganisms that live in a dog's fur. These yeast and bacteria poops don't smell when they are dry but as soon as water hits them they start breaking apart and creating a fog of musk around your dog, according to Wired.

Getting wet makes a dog smell worse because those compounds are better able to escape from the furry confines of a dog's coat. As it evaporates, the water in the dogs coat lifts those molecules up and out of the fur, and all the way up to our noses.

This could be even worse if it's humid outside. The more moisture air holds, the more it can transfer smells to your nose.

While wet dog smell might offend some human olfactory senses, dogs probably experience it differently. Dogs have 220 million olfactory receptors give them a sense of smell stronger than anything we humans can experience. Even the mucus on their nose helps them efficiently process smells.

All those smelling powers that a dog possesses they usually direct towards sniffing out disgusting smells. It turns out dogs are attracted to smells produced by molecules that scientists describe as causing the 'dead body smell.'

Watch the whole video, from the American Chemical Society's YouTube channel, for more canine chemistry:

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This flowerpot full of red powder looks pretty innocuous. 

But when ignited with a strip of magnesium and a blowtorch, it yields a molten metal so hot it keeps burning underwater. 

The red powder in question is thermite, a mixture of finely powdered rust and aluminum that burns at a temperature of over 4,000 degrees Fahrenheit. 

In a video uploaded to his YouTube channel, TheBackyardScientist demonstrated what various metals did when he melted them and poured them into a fish tank full of water. 

For thermite, the result is liquid iron so hot water can't put out the fire: 

Once you get over the initial shock of what you're seeing, watching the fiery chunks of metal sink is mesmerizing. 

The silvery blobs you can see rushing upward are bubbles of gas formed when the water that comes in contact with the molten metal boils. 

As the iron slowly cools, chunks of it (and another byproduct, aluminum oxide) settle at the bottom of the tank, still shedding bubbles: 

Watch TheBackyardScientist melt other metals and pour them into water:

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Humidity is rising and thermometers are creeping into the triple digits — all signs that the 4th of July is fast approaching.

Between dazzling fireworks and delicious cold brews, millions of people will be firing up their grills and throwing on tenderloins, flank steaks, pork shoulder and many more combinations of savory meats to celebrate.

But what actually happens to the meat when it hits high heat that makes it so mouthwatering?

The video below, from our friends at the American Chemical Society, explains the delicious chemical reactions that transform a bloody chunk of meat into a tasty browned steak.

Before it touches the grill

A common misconception is that the red color of meat comes from blood, but the muscle's ruby red hue actually stems from the animal's behavior. Cows spend a ton of time standing, so their muscles must be able to withstand their weight for long stretches of time without fatiguing.

This creates lots of slow-twitch muscle fibers, which are more efficient at consuming oxygen and transforming it into energy because they contain more of a special protein called myoglobin, which turns red when it's bound to oxygen. The more myoglobin a piece of meat has, the redder it will be.

The same thing happens in the muscles of people who engage in endurance sports, like marathons and long-distance swimming.

If a package of meat appears grayish, the video explains, it just means that the meat's myoglobin isn't attached to oxygen. When you open the package and re-expose the meat to air, the surface of the meat will regain its ruby tint.

Eventually, however, oxygen-exposed meat will turn back to gray — a sign that it's gone bad.

To side-step this, many grocery stores package their meat under carbon monoxide — the carbon monoxide stops the oxygen from reacting with the muscle over time, keeping it red.

Get that charcoal out

To perfect that barbecue flavor, you need some charcoal. While gas is convenient, it totally misses the mark in terms of good barbecue.

Many people don't realize that charcoal is actually wood that's been heated in the absence of oxygen. Wood chips contain a chemical compound called lignin which, when fired up, gets broken down and produces another compound called guaiacol. The guaiacol in the charcoal is what then produces that deep, smokey wood fired flavor.

And if that isn't enough, when juices from the meat drip onto the charcoal, they produce even more delicious-tasting compounds that float upwards and saturate the meat with even more flavor.

Fire it up

The heat of the grill also changes that myoglobin — above 140 Fahrenheit, the molecule unfolds to the point where it can't hold onto oxygen and turns a tan color due to a compound called hemichrome. At about 170 Fahrenheit, myoglobin unfolds again into a new structure called metmyoglobin, which looks a darker grayish brown.

But the "holy grail of all culinary chemical reactions," according to the video, is when the Maillard reaction rearranges the amino acids and sugars in the muscle meat to produce the quintessential browned color and mouthwatering taste of barbecue.

This rearrangement occurs at around 285 Fahrenheit giving browned meat its distinctive color and flavor.

Overzealous grillers beware

It may be tempting to go overboard with that char to get more grilly flavor, but searing your meat into oblivion has some pretty nasty consequences. Not only does the meat lose its mouth-watering flavor and texture, but it also produces potentially cancer-causing compounds.

This can all be avoided by cooking your meat at lower temperatures and flipping it often. Insider tip: Invest in a meat thermometer to make sure your meat isn't overdone.

Happy barbecuing!

Watch the full video, from the American Chemical Society's Reactions channel, on YouTube:

SEE ALSO: Here's how long meat can stay frozen without spoiling

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If you're hitting the beach and frolicking in the waves this summer, that glowing tan and beach-tussled hair may not be the only thing you're coming home with. That sea salt may be leaving your skin dry, cracked, and flaky.

Your skin is the largest organ in the body and the first line of defense against harmful microbes, pollution, and UV rays.

In scientific terms, your skin is technically "dry" when its moisture level is less than 10%. That's when you're most likely to smother yourself in body lotion.

But how do moisturizers work their skin-smoothing magic in the first place?

Cracked, flaky, and dry skin — which tends to occur when humidity drops in the chilly months — goes by a mouthful of a scientific name: transepidermal water loss, or TEWL.

At its simplest, TEWL is a measure of how much water seeps from the inside of the body through the different layers of the skin and out into the atmosphere.

Especially dry, irritated, or inflamed skin is also called xerosis, which is usually a minor and temporary problem that can be solved with good moisturizing lotions.

Here's how moisturizers work.

There are three different layers of the skin: the outer layer (epidermis), middle layer (dermis), and lower layer (hypodermis or fatty layer).

Moisture is delivered to the skin via blood vessels, but they only supply moisture to the middle layer of the skin — the dermis. From there, water travels upward and outward through the epidermis before evaporating into the atmosphere.

This evaporation causes skin to crack and flake. This process happens constantly, but skin isn't always dry. That's because the dryer the air the more moisture it will pull from your skin.

Moisturizers work in one of two main ways: they either trap moisture in your skin to keep it from escaping, or they restore moisture in the outer layer of skin that's already been lost.

With the glut of lotions and creams on the market, it can be easy to get lost in the sea of brand-named jellies. At the most basic level, however, there are three types of moisturizers. Each works slightly differently, but most products combine all three.

Occlusives

These are called the "old school" or "first generation" moisturizers — think petroleum jelly or its brand name, Vaseline. This class of waxes, oils, and silicones work in a very simple way: They create a barrier over the skin, trapping water in the skin's layers and stopping evaporation.

The molecules in these moisturizers contain long chains of carbon atoms that repel water. While occlusives are super effective at minimizing dryness — they cut TEWL by a whopping 98%— they can be sticky, messy, and not very cosmetically appealing.

Emollients

This class of moisturizer, which exists in the form of creams, ointments, lotions, and gels, are generally preferred over occlusives because they feel less sticky. Whereas occlusives coat the skin, emollients penetrate it, making the skin feel soft and flexible.

Emollient products are made with a variety of chemicals, but their basic building blocks are the same as occlusives — long chains of carbon atoms that repel water. Emollients work a little differently than occlusives, though.

Think of the outer layer of skin as a brick and mortar structure: the dead skin cells are the bricks and surrounding matrix of fats and proteins are the mortar. Special proteins link the dead cells together, forming a barrier between the inside of the body and the bacteria and chemicals outside, as demonstrated in this video by the American Chemical Society:

When the air gets dry, it dries out this matrix, and the links between the proteins and skin cells fall apart and fracture. Emollients are like cement in those gaps, restoring moisture and keeping skin smooth.

Humectants

Humectants work by attracting moisture to the skin and keeping it there. This is basically the opposite of occlusives and emollients, which don't like water. Humectants penetrate the outer layer of the skin, attract water to it, and lock that moisture in.

This happens because humectants have hydroxyl groups in their chemical structure (an oxygen and a hydrogen atom), which loves water. Humectants also prompt the production of ceramides, our body's natural waxy molecules that play a major role in the structure of the skin.

But beware, in dry conditions, humectants can draw moisture from the younger, moist cells in the lower layers of the skin instead of pulling moisture from the air. Over time, this could eventually lead to even dryer skin. Minimize this by pairing a humectant with an occlusive, which seals in the moisture.

You should also check out the full video from the American Chemical Society's Reactions channel on YouTube:

If you need help selecting a good lotion, there are a few guides like this one that stand up to consumer and scientific testing. And if lotions aren't enough, try turning down your heat or investing in a humidifier.

Stay moisturized, people!

SEE ALSO: How Sunscreen Works

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