Supercooled Water at Record-Low Temperatures Acts Like Two Liquids at Once

Scientists have reached a new low in the cooling of liquid water, hitting -45 degrees Celsius (-49 degrees Fahrenheit). That's way below the usual freezing point, and shows we still have a lot to learn about the physics of this plentiful substance.

In two separate experiments, water was supercooled right down to 230 Kelvin and 227.7 Kelvin, which is -43.15°C (-45.67°F) and -45.45°C (-49.81°F), respectively. At these kind of extreme temperatures, it's almost as if water becomes two different types of liquid, the scientists say – fluctuating between two different states in the same way that we might deliberate over a decision. We already know that water can stay as a liquid below zero degrees Celsius (32°F) in certain situations, such as clouds high up in the atmosphere. In fact, the freezing effect is dependent on a number of factors affecting the molecules inside water and how quickly they crystallise. Scientists have previously been able to delay this freezing, which happens when an initial crystal nucleus forms and begins attracting other molecules, but so far no one's sure just how cold we can get water and still keep its molecules flowing.

"The new remarkable property is that we find that water can exist as two different liquids at low temperatures where ice crystallisation is slow," says one of the researchers, Anders Nilsson from Stockholm University in Sweden. Nilsson and his colleagues were the ones to hit 227.7 Kelvin, using microscopic droplets of water propelled into a vacuum (the smaller the droplet, the easier it is to keep from freezing). Using advanced X-ray scans, they noticed water of two different densities coexisting together. The researchers saw "how a glassy state of water transforms into a viscous liquid which almost immediately transforms to a different, even more viscous liquid of much lower density," says one of the team, Katrin Amann-Winkel from Stockholm University.

This coexistence of two densities at a certain super-cool temperature has in fact been predicted before, but this is the first evidence we've seen of it actually being real – evidence that could inform many different areas of research, from food preservation to cryogenics (you wouldn't want your body icing up on a deep space trip, after all). The second experiment, run by a different international team of researchers, again used microscopic droplets of water inside a vacuum. This time the study demonstrated how the extremely low pressure levels produced evaporation cooling that outpaced the crystallisation process. That led to the ultra-low cooling point of 230 Kelvin before freezing began to take place. Special laser techniques were required, measuring the size of droplets to gauge their temperature, and this same approach could be used again to study super-cooled water in the future, the researchers say. "The easiest way to determine the temperature of a spherical droplet was to measure its size, which can be accurately determined by exploiting the presence of an interference pattern in the light scattered by the droplet," senior author, Robert Grisenti from the University of Frankfurt in Germany, told Sam Jarman at Physics World.

Eventually, the technique could even be adapted to measure droplets in the Earth's atmosphere, and improve our understanding of the planet's changing climate. This is the first time we've been able to observe liquid water at such a low temperature, which means there's still some debate over how accurate these readings are and whether we can push them any further. What everyone seems to agree on is that these are important areas of research for understanding more about the properties of water, which is key to the health of our planet and life itself. And we now have a new perspective on it. As one of the researchers from the first experiment, Lars G.M. Pettersson from Stockholm University puts it: "In a nutshell: Water is not a complicated liquid, but two simple liquids with a complicated relationship." The research has been published in Science and Physical Review Letters.

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This May Be The Year We Will See a Black Hole For The First Time

Scientists have reached a new low in the cooling of liquid water, hitting -45 degrees Celsius (-49 degrees Fahrenheit). That's way below the usual freezing point, and shows we still have a lot to learn about the physics of this plentiful substance.

In two separate experiments, water was supercooled right down to 230 Kelvin and 227.7 Kelvin, which is -43.15°C (-45.67°F) and -45.45°C (-49.81°F), respectively. At these kind of extreme temperatures, it's almost as if water becomes two different types of liquid, the scientists say – fluctuating between two different states in the same way that we might deliberate over a decision. We already know that water can stay as a liquid below zero degrees Celsius (32°F) in certain situations, such as clouds high up in the atmosphere. In fact, the freezing effect is dependent on a number of factors affecting the molecules inside water and how quickly they crystallise. Scientists have previously been able to delay this freezing, which happens when an initial crystal nucleus forms and begins attracting other molecules, but so far no one's sure just how cold we can get water and still keep its molecules flowing.

"The new remarkable property is that we find that water can exist as two different liquids at low temperatures where ice crystallisation is slow," says one of the researchers, Anders Nilsson from Stockholm University in Sweden. Nilsson and his colleagues were the ones to hit 227.7 Kelvin, using microscopic droplets of water propelled into a vacuum (the smaller the droplet, the easier it is to keep from freezing). Using advanced X-ray scans, they noticed water of two different densities coexisting together. The researchers saw "how a glassy state of water transforms into a viscous liquid which almost immediately transforms to a different, even more viscous liquid of much lower density," says one of the team, Katrin Amann-Winkel from Stockholm University.

This coexistence of two densities at a certain super-cool temperature has in fact been predicted before, but this is the first evidence we've seen of it actually being real – evidence that could inform many different areas of research, from food preservation to cryogenics (you wouldn't want your body icing up on a deep space trip, after all). The second experiment, run by a different international team of researchers, again used microscopic droplets of water inside a vacuum. This time the study demonstrated how the extremely low pressure levels produced evaporation cooling that outpaced the crystallisation process. That led to the ultra-low cooling point of 230 Kelvin before freezing began to take place. Special laser techniques were required, measuring the size of droplets to gauge their temperature, and this same approach could be used again to study super-cooled water in the future, the researchers say. "The easiest way to determine the temperature of a spherical droplet was to measure its size, which can be accurately determined by exploiting the presence of an interference pattern in the light scattered by the droplet," senior author, Robert Grisenti from the University of Frankfurt in Germany, told Sam Jarman at Physics World.

Eventually, the technique could even be adapted to measure droplets in the Earth's atmosphere, and improve our understanding of the planet's changing climate. This is the first time we've been able to observe liquid water at such a low temperature, which means there's still some debate over how accurate these readings are and whether we can push them any further. What everyone seems to agree on is that these are important areas of research for understanding more about the properties of water, which is key to the health of our planet and life itself. And we now have a new perspective on it. As one of the researchers from the first experiment, Lars G.M. Pettersson from Stockholm University puts it: "In a nutshell: Water is not a complicated liquid, but two simple liquids with a complicated relationship." The research has been published in Science and Physical Review Letters.

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These 8 Steps Will Prepare You For a Good Night's Sleep

Wondering when to stop drinking coffee and using screens to avoid messing with your sleep? How frequently you should wash your sheets? Scientists have been looking for answers to these questions too. You can use their answers to guide many of the decisions you make on a nightly basis, from what you drink at night to how often you do laundry.

1. Watch your mid-afternoon caffeine intake.

The Mayo Clinic advises adults to limit their caffeine intake to 400 mg per day, or the equivalent of about two to three coffees. Caffeine content can differ dramatically based on the type of coffee, however. Just 1.5 cups of Starbucks contains 400 mg of caffeine, while you'd need four cups of McDonald's drip coffee to equal that amount. Like too much of anything, excess caffeine comes with risks, including migraine headaches, irritability, upset stomach, and even muscle tremors – so it's important to know how much you're getting.

2. On your commute home, don't agonise over germs.

A team of geneticists made headlines in 2015 for a mission to document all the bacteria on the New York City subway. They turned up nearly 600 different species of microbes crawling around on all those greasy rails. Before whipping out the hand sanitiser and tissues, keep this in mind: Almost all of the germs they found were completely harmless. In fact, there's evidence to suggest that regular exposure to germs helps keep our immune systems healthy by priming it to more easily recognise dangerous microbes in the future. The idea could partially explain why children who grow up around animals and in rural areas are less likely to develop conditions like asthma than children who don't.

3. Skip happy hour, or go simply for the food and company.

Alcohol is one of the world's most widely consumed drugs, but drinking even small amounts – as little as one glass of wine or beer a day – has been linked with a host of negative side effects, including cancer. In November, the American Society of Clinical Oncology, a group of the nation's top cancer doctors, released an unprecedented warning in which it told Americans to drink less. "ASCO believes that a proactive stance by the Society to minimise excessive exposure to alcohol has important implications for cancer prevention," the statement said. So at your next happy-hour event, consider skipping the booze or doing something else.

4. Stay hydrated

Staying hydrated is vital. Our bodies are 60 percent water, and not getting enough can lead to headaches, fatigue, and even overeating. Still, contrary to popular opinion, you don't necessarily need to drink eight glasses of water a day. Instead, your daily hydration requirement can change based on several factors, from how much you worked out that day to the weather outside. Certain foods are also a good water source, so eating more of them may mean you need to drink less. Cauliflower, eggplant, peppers, and spinach are all 92 percent water. Carrots, green peas, and even white potatoes are more than 79 percent.

5. Take breaks from screens to avoid eye strain.

Many of us go from starting at computers to staring at our phones, and as a result our eyes are often dry, itchy, blurry, or irritated. Ophthalmologists call this condition "digital eyestrain." To avoid it, make sure you're drinking (and blinking) enough and avoid reading your phone under the glare of a lamp. You can also practice what's known as the 20-20-20 rule. Every 20 minutes, look at something at least 20 feet away for 20 seconds. This will allow your eyes to rest, Rahul Khurana, the clinical spokesman for the American Academy of Ophthalmologists told my colleague Kevin Loria.

6. If you go out for dinner, plan on taking up to a third of it home.

The baseline portion sizes of our snacks and meals have ballooned over the past 40 years – even the plates and cups we serve them on have gotten noticeably bigger. The average size of many of our foods – whether fast food, sit-down meals, or even items from the grocery store – has grown by as much as 138 percent since the 1970s, according to data from the American Journal of Public Health, the Journal of Nutrition, and the Journal of the American Medical Association. So be mindful of portion sizes, and if you're eating out, consider taking anywhere from a third to half of it to go.

7. Put away screens for at least 30 minutes before bedtime.

The blue light that illuminates our screens also tamps down on the production of melatonin, a key hormone our brains use to tell our bodies to start preparing for sleep. That's something you don't want to be doing at night, especially right when you're heading to bed. Experts recommend at least 30 minutes of no-screen time before bedtime.

8. Before you tuck in for the night, make sure your sheets are clean.

Our beds can blossom into a "botanical park" of bacteria and fungus in as little as a week, New York University microbiologist Philip Tierno told Business Insider. The combination of sweat, animal dander, pollen, soil, lint, dust-mite debris, and plenty of other things is enough to make anyone sick, let alone someone with allergies. So clean your sheets at least once every seven days.

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Astronomers Find a Spectacular Source For Those Mysterious Repeating Space Signals

Fast radio bursts (FRBs) are one of our Universe's most confounding mysteries - but astronomers may have just figured out the incredible environment where one of the most famous and well-studied FRBs is coming from. The repeating radio signals from FRB 121102 are likely produced somewhere extreme, like the area around a massive black hole.

FRB 121102 made its first appearance in November 2012, but it took researchers a few years before pinning down its unusual nature. Most fast radio bursts only occur once, which makes them untraceable - but FRB 121102 would go on to repeat. This afforded a unique opportunity. Fast radio bursts are extremely powerful radio signals, generating as much energy as 500 million suns, but they're also extremely short, lasting just milliseconds. Because most of them burst once and never return, they are impossible to predict, and impossible to trace. This is one of the main reasons why we don't know what causes them.But FRB 121102 has proved to be exceptional. In March 2016, researchers announced they'd found 10 other bursts from the same location in archival data. Then in December 2016, 6 bursts were detected from FRB 121102; then 15 more in August 2017.

This allowed researchers to locate the source of these signals - a star-forming region in a dwarf galaxy more than 3 billion light-years from Earth. And now an international team of researchers has narrowed it down further still, by studying data from radio telescopes that collected the signal - and are more convinced than ever that the source is a neutron star. But if it is a neutron star, it's in a crazy environment - either very close to a black hole or in a very powerful nebula. This is because of the way the radio signal is "twisted".The radio signals of FRB 121102 are almost completely polarised. When these polarised signals travel through a magnetic field, they become twisted - the stronger the field, the greater the twist. This is called Faraday rotation, and it allows researchers to learn more about the waves' origin.

In the case of FRB 121102, the twisting of the signals' polarisation is some of the greatest ever observed, which means they had to pass through a very intense magnetic field. "The only known sources in our galaxy that are twisted as much as FRB 121102 are in the Galactic Centre, which is a dynamic region near a massive black hole. Maybe FRB 121102 is in a similar environment in its host galaxy," said PhD candidate Daniele Michilli of the University of Amsterdam and ASTRON, the Netherlands Institute for Radio Astronomy. "However, the twisting of the radio bursts could also be explained if the source is located in a powerful nebula or supernova remnant." This is consistent with the neutron star hypothesis. Neutron stars are one result of massive star undergoing a core-collapse supernova. (If it is greater than a certain mass, the star will turn into a black hole instead.) They are very small, and very dense, and they emit radio pulses as they spin. A type of neutron star called a magnetar has an extremely strong magnetic field, and these can produce bursts - similar to how the Sun produces solar flares.

This has been proposed as a possible source of the fast radio bursts. However, the most powerful of these flares ever observed has been four orders of magnitude below FRB 121102. The researchers believe that the source is a regular neutron star, and are hoping to find out more. "We are continuing to monitor how the properties of the bursts change with time," said Jason Hessels from the University of Amsterdam and ASTRON.With these observations we hope to distinguish between the two competing hypotheses of a neutron star either near a black hole or embedded in a powerful nebula." Meanwhile, we still don't have a lead on the dozens of other fast radio bursts that have been observed. And, because they don't repeat - FRB 121102 is the only repeater - it's very possible that FRB 121102 is unique in its source, and the others emanate from different sources. The researchers presented their findings at the 231st meeting of the American Astronomical Society, and their paper has been published in the journal Nature.

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5 years to Jupiter and here's what NASA found

NASA's $US1 billion Juno spacecraft completed its 10th high-speed trip around Jupiter on December 16. The robot gets relatively close to the gas giant planet and takes new photos with its Juno Cam instrument roughly every 53 days, while travelling at speeds up to 130,000 mph (209,000 km/h). It can take days or sometimes weeks to receive the images, but the wait is worth it. The latest batch of photos features countless swirling, hallucinatory clouds and storms.

Researchers at NASA and the Southwest Research Institute uploaded the raw image data to their websites in late December. Since then, dozens of people have processed the black-and-white files into gorgeous, calendar-ready colour pictures.

"As pretty as a planet can get, but get too close and Jupiter will END YOU," Sean Doran, a UK-based graphic artist who regularly processes NASA images, said about the new images in a tweet.

Here are some of the best new photos and animations made with JunoCam data by Doran and other fans of the spacecraft.

NASA launched Juno in 2011, and it took nearly five years for the probe to reach Jupiter.

Juno's orbit takes it far beyond Jupiter - then quickly and closely around the world - to minimise exposing electronics to the planet's harsh radiation fields.

During each 53.5-day orbit, called a perijove, JunoCam records a new batch of photos. The spacecraft is the only one ever to fly above and below Jupiter's poles.

Researchers are trying to make sense of the gas giant's swirling mess of polar cloud formations, like these captured during Juno's tenth perijove. The planet's many bands of cloud groups are also a scientific puzzle. Some of the storms seen on Jupiter are larger than Earth's diameter.

A full set of JunoCam images looks like this:

But some fans of the spacecraft have figured out how to stitch them together into time-lapse movies. NASA expects Juno to orbit Jupiter for at least a couple more years, and continue beaming back incredible new pictures. However, the space agency will eventually destroy the $US1 billion robot. This will prevent an accidental crash into Jupiter's icy moon Europa, which may harbour an ocean - and potentially alien life. Here's half of Jupiter's icy moon Europa as seen via images taken by NASA's Galileo spacecraft in the late 1990s.

       Source : ScienceAlert

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Electric roads to be a reality soon?

Fifty years ago the Beach Boys had a hit with Good Vibrations. Now Los Angeles, home city of the superstar group, is trying to figure ways to turn its immense traffic burden into clean energy.

One promising project involves generating electricity from crystals embedded in LA's road surfaces from the vibrations of passing vehicles. The process uses piezoelectric crystals, which produce tiny electrical charges when compressed. By one estimate, cars running over 20km of charged highway could generate enough power to run the city of Burbank, home to 100,000 people. For the trial, crystals set in devices the size of a small coin will be laid in a highway just a few millimetres apart.

Over 18 months, the performance of the electric road will be measured to get a feel for whether the technology can deliver. In Europe, a different tack is being taken with electric roads, one designed to keep electric cars charged as they roam the transport network. US chipmaker Qualcomm has devised a wireless charger for electric vehicles, which lets battery-driven cars collect their energy from cables laid under the road surface.

With heavy investment being poured into the sector, the cable roads offer a solution to the imminent point when electric vehicle prices fall to the level of fossil-fueled cars and there are too many electric machines for top-up chargers.

The technology is currently confined to test tracks and no one has solved the costly challenge of laying cables beneath motorway lanes that are capable of delivering a charge to vehicles speeding over them. However, industry enthusiasts say "watch this space". Edouard Fischer, a director at Sanef, the company that operates France's toll motorways told a summit on the future of the car that the industry had to think about new things. "We must prepare for what will happen in 10 to 15 years."

Source: electroad.me / NZ Herald

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