Tag Archives: sodium

Sodium chloride.

Cloud-free exoplanet provides best evidence of sodium in planets outside our solar system so far

A cloudless exoplanet has become a benchmark for astronomers to gauge sodium content in alien worlds.

Sodium chloride.

Sodium chloride (table salt) crystal.
Image credits Amanda Slater / Flickr.

An international team of astronomers, led by researchers from the University of Exter, has uncovered one far-off world that will help us better understand the chemical make-up of planets beyond our solar system. Dubbed WASP-96b, this ‘hot Saturn’ planet is completely devoid of clouds — making it an ideal subject for astronomers trying to determine its atmospheric composition.

Peering through the 8.2-meter lens of ESO’s aptly named Very Large Telescope in Chile, the team observed WASP-96b as it was transiting in front of its host star. This method of study is the bread and butter of astronomers studying far-off planets. By measuring the dip in starlight incoming to Earth while this transit takes places, they can determine the planet’s size. By looking at its spectral emissions — carried to us by the photons passing through the atmosphere — they can gauge the chemical make-up of the planet’s gaseous cover.

Spectral emissions are like fingerprints for atoms since each element and isotope has its own signature — a characteristic astronomers are more than happy to exploit when pointing their instruments at far-off celestial objects. WASP-96b’s spectrum showed the complete signature of sodium, the team writes, which is only observable in atmospheres completely devoid of clouds.

Reflections so dium you can see everything!

Just like an individual’s fingerprints are unique, atoms and molecules have a unique spectral characteristic that can be used to detect their presence in celestial objects. The spectrum of WASP-96b shows the complete fingerprint of sodium, which can only be observed for an atmosphere free of clouds. The finding is especially exciting for astronomers, who have long suspected that hot, gas-giant exoplanets harbor sodium — but have never actually had any proof to back their suspicion.

On first glance, WASP-96b doesn’t seem very special. It’s a gas giant, very similar to Saturn in mass, but about 20% larger than Jupiter, set to a simmery 1300°K (~1027°C or 1900°F). It’s about 980 light-years away from Earth, in the Phoenix constellation, and orbits a pretty-much sun-like star. Here is a visualization of it transiting in front of its host, put together by co-author Ernst de Mooij:

 

Spectral emissions recorded while WASP-96b transited in front of its host star, however, made the planet’s uniqueness apparent. Based on the sodium signature observable in these records, the team found that the planet’s atmosphere is completely free of clouds. This allowed the team to measure how abundant sodium is in the atmosphere. The researchers report finding levels similar to those seen in our own Solar System.

“We’ve been looking at more than twenty exoplanet transit spectra,” said Nikolay Nikolov, paper lead author. “Until now, sodium was revealed either as a very narrow peak or found to be completely missing. This is because the characteristic ‘tent-shaped’ profile can only be produced deep in the atmosphere of the planet and for most planet clouds appear to get in the way”.

That ‘tent-shaped’ bit he mentions refers to one of the two ways emission spectra are most often represented in charts: constituted of one wiggly horizontal line (that indicates a baseline value, i.e. no emission in that segment of the spectrum), dotted here and there with ‘peaks’ or ‘spikes’ (these indicate a higher value, i.e. registerable emission in that segment of the spectrum). A ‘tent-shaped’ spike on the profile indicates strong emission in one particular wavelength interval — based on which researchers can gauge the presence of particular elements.

The presence of clouds, hazes, mists, or similar phenomena in an atmosphere has the ability to block and reflect incoming light, altering its spectral output. Sodium’s emission is especially affected, as Nikolov explains, because its profile is produced in the lower layers of the atmosphere (i.e. below clouds, hazes, or mists).

So far, WASP-96b is the only exoplanet to we’ve found with a clear sodium signature, making it ideal as a benchmark for the presence of this element in other worlds of its kind.

“WASP-96b will also provide us with a unique opportunity to determine the abundances of other molecules, such as water, carbon monoxide and carbon dioxide with future observations,” adds co-author Ernst de Mooij.

Sodium is the seventh-most abundant element in the Universe, and vital to life as we know it. Organisms on Earth depend on sodium (in the form of table salt) for survival, and is widely used in industry. Knowing how to find it on other worlds from afar would thus be a great skill to have — both when looking for alien life or a nice place to settle.

The paper “An absolute sodium abundance for a cloud-free ‘hot Saturn’ exoplanet” has been published in the journal Nature.

Chinese food is too salty and should have label warnings, study calls

An analysis of more than 150 Chinese dishes found that many of them contain disturbingly high amounts of salt — some being five times more salty than a Big Mac. Study authors call on policymakers to make health labeling mandatory.

Mapo Tofu is one of my favorites. Image credits: Guilhem Vellut.

Sweet sour pork, Kung Pao chicken, Mapo tofu — these staples of Chinese cuisine (and many others) have become increasingly popular in the Western World. With over 22 million takeaways eaten every week in the UK alone, understanding the health impacts of these foods is a significant concern. With this in mind, Action on Salt, a group concerned with salt and its effects on health, supported by 25 expert scientific members, analyzed 150 Chinese foods.

They found that both supermarket and takeaway Chinese food dishes were laden with salt, with the worst offenders having five times more salt than even the Big Mac. Out of the tested foods (all in the UK), 97% contained a hefty 2g of salt or more per dish. Over half (58%) contained more than 3g of salt per dish — half of the recommended daily intake in the UK, 6g of salt (the World Health Organization recommends no more than 5g of salt). The study reads:

“Chinese meals should carry a health warning on packaging and menus after a new survey based at the Wolfson Institute, Barts & The London, Queen Mary University of London has exposed the astonishing and harmful amounts of salt found in both Chinese takeaways and Chinese ready meals sold by some of the UK’s biggest supermarkets. The group of leading experts is now calling on Public Health England (PHE) to get tough on setting new salt targets, making front of pack labelling mandatory and put warning labels on menus for dishes high in salt.”

Image credits: Dubravko Sorić.

Main courses (such as beef in black bean sauce) topped the list, but accompanying dishes such as rice, spring rolls or prawn crackers can also add to the total salt quantity. Soy sauce, a staple of Chinese cuisine, is extremely salty, but sweet sauces and foods can also contain impressive amounts of salt (which is often used as a flavor enhancer).

According to the Center for Disease Control and Prevention (CDC) and the WHP (and really, any health organization), excess sodium (‘table salt’ is a sodium salt) can increase blood pressure and the risk of heart disease and stroke.

“Salt is the forgotten killer as it puts up our blood pressure, leading to tens of thousands of unnecessary strokes, heart failure and heart attacks every year,” said Graham MacGregor, the chairman of Action on Salt and a professor of cardiovascular medicine at Queen Mary University of London.

The findings are concerning, and Action on Salt says that the first step towards tackling this issue is labeling — having a visual warning could help to make people more aware of how much salt they are consuming.

Results have not been peer-reviewed.

Having a healthy diet doesn’t offset high salt consumption

A new study contradicts the belief that eating a healthy, but salty diet, is alright. Even if you eat a lot of fruits and vegetables, you may still suffer the negative effects of high salt consumption.

Processed foods are one of the main culprits for the extra salt in our meals.

It was previously thought that vitamins and minerals in fruits and vegetables affect blood vessels in a way that allows them to lower blood pressure, but this new research, which analyzed the diet and overall health of over 4,000 people, found that that’s not really the case.

An international team of researchers assessed concentrations of sodium and potassium in the urine samples of 4,680 people, aged 40-59, from the USA, UK, Japan, and China. The study participants were tracked over four days, during which they gave urine samples two times. Sodium is one of the two elements of salt and has been linked to increased blood pressure, while potassium, which is commonly found in legumes and vegetables, has been associated with lower blood pressure. Researchers also tracked the volunteers’ intake of over 80 nutrients that may be linked to low blood pressure, including vitamin C, fibers, and omega-3 fatty acids.

Researchers were expecting to find an inverse correlation between sodium and potassium, but they found that no matter how many fruits and veggies people ate, high salt intake was associated with high blood pressure; on average, an additional 7g (1.2 teaspoons) of salt above the average intake was associated with an increase in systolic blood pressure of 3.7 mmHg.

Dr. Queenie Chan, joint-lead author of the research from the School of Public Health at Imperial College London, said that this can be extremely important, especially as high blood pressure affects between 16 and 37% of the population globally. A 2010 study found that hypertension is a factor in 18% of all deaths (9.4 million globally), with processed foods being one of the main culprits.

“We currently have a global epidemic of high salt intake – and high blood pressure. This research shows there are no cheats when it comes to reducing blood pressure. Having a low salt diet is key – even if your diet is otherwise healthy and balanced.”

“As a large amount of the salt in our diet comes from processed food, we are urging food manufacturers to take steps to reduce salt in their products,” she added.

However, researchers emphasize that they only tracked volunteers for four days, so they only recorded a snapshot of their lives. In the future, they plan to expand a similar study on a longer period of time, and with more participants.

Lifestyle changes can be extremely effective in reducing high blood pressure. Eating a healthy diet and having an active lifestyle is extremely important in reducing sodium blood levels. Extra pounds and high blood pressure go hand in hand. Alcohol and cigarettes can also contribute to raising blood pressure.

The results have been published in the journal Hypertension.

Atom-by-atom chart of living fossil’s shell could hold the key to understanding past climate

American researchers adapted two nano-scale investigation techniques traditionally used in material sciences to take an atom by atom look at how foraminifera build their shells. The advance not only provides insight into the process of biomineralization, but will also allow us to better track the environmental history of the Earth.

Orbulina universa.
Image credits Howard Spero / UC Davis.

The team of researchers from University of California, Davis, University of Washington, and the U.S. Department of Energy’s Pacific Northwest National Laboratory developed a novel way of studying the growth patterns of foraminifera (“forams”), a type of plankton. The team created an organic-mineral interface where they could observe how calcium carbonate crystals grow in the shells.

They used two cutting-edge techniques to perform their examination: Time-of-FLight Secondary Ionization Mass Spectrometry (ToF-SIMS) and Laser-Assisted Atom Probe Tomography (APT). ToF-SIMS creates a two-dimensional chemical map of a sample’s polished surface. It was first used to perform elemental analysis of complex polymers, but it’s now finding its way to applications on natural shells. APT was first developed to analyze internal structures of alloys, silicon chips, and superconductors and results in a three-dimensional chemical map.

With these methods, the team zoomed in down to the atomic level to understand how trace impurities find their way into shells during the growth process — or biomineralization. They focused on a critical stage of the process — the interaction between the shell’s biological template and the initiation of growth.

“We’ve gotten the first glimpse of the biological event horizon,” said Howard Spero, a study co-author and UC Davis geochemistry professor.

From their observations, the team created an atomic-scale map of the chemistry taking place at this key point in time for Orbulina universa forams. This is the first ever chemical record of a calcium carbonate biomineralization template. Some surprising findings were higher-than-expected levels of sodium and magnesium in the organic material. These two elements weren’t considered as important for the overall architecture of the shells, said lead study author Oscar Branson. The finding means we can better account for these two elements when investigating paleoclimate from foram shells.

Why does that even matter?

Well, together with ice core samples, foram shells are the only medium we have that records climate conditions throughout the Earth’s past. They’ve been around for some 200 million years (surviving even asteroid impacts), raining down layers of shells on the ocean floor when they die. As the shells grow, they absorb minerals from the surrounding seawater, such as calcium, magnesium, sodium, so on. How much of each is available in the water, and how much of each is absorbed, depends directly on environmental conditions. The warmer the water was where the shell grew, the more magnesium it will contain, for example.

So by analyzing the shells’ chemical makeup, we can determine how climate conditions changed over this 200m years period.

“Finding out how much magnesium there is in a shell can allow us to find out the temperature of seawater going back up to 150 million years,” Branson said.

But each shell is composed of countless nanometer-scale bands — similar to how trees have growth rings. Element concentrations vary between these bands as well, not just between shells.

“We know that shell formation processes are important for shell chemistry, but we don’t know much about these processes or how they might have changed through time,” he said. “This adds considerable uncertainty to climate reconstructions.”

The new findings will hopefully allow us to better tune our investigations in the future, so we can create more accurate climate records of the past.

The full paper “Atom-by-atom growth chart for shells helps decode past climate” has been published in the journal Nature.

 

What happens when you throw a pound of Sodium like a skipping stone in a river

Warning: Don’t try this at home!

One wiseguy Youtuber called EatsTooMuchJam skipped a pound of sodium across a river for science. What happened next was totally predictable, but still amazing to watch like any spontaneous explosion. It was also a very expensive science experiment, too. One pound of 99.8% sodium metal ingots sells for $180 over at Amazon.

The reaction between sodium and water is one the most spectacular in chemistry. Being a highly reactive metal, when sodium comes into contact with water, it displaces hydrogen gas per the following:

2 Na(s) + 2H2O(l) –> 2 NaOH(aq) + H2(g)

 

The reaction produces jets of hydrogen gas below the water, which propels the sodium. The reaction also releases a lot of heat, and as the sodium and solution warm up, it goes faster. If sodium gets hot enough, the hydrogen jet can ignite and burn, rising the temperature of the reaction even further. This raises the reaction time so quickly that an explosion may occur — which is exactly what happened here.

Teens: Forget the salt, eat more bananas

In the modern world, we tend to eat more salt than we should, and that can have several negative impacts on our body, including higher blood pressure – or so we thought. But a new study on teenage girls found that salt has no negative effect on blood pressure; bananas do.

“It may be that potassium is more of a determinant of blood pressure than sodium is,” said Lynn L. Moore, the study’s lead author and an associate professor of medicine at Boston University. “The kids who consumed the most potassium had much lower blood pressures by the end of adolescence. What we need to focus on is increasing potassium intake rather than focusing on restricting sodium intake.”

The study tracked the eating habits of 2,185 girls aged 9-10 for 10 years, and their findings were pretty surprising: salt intake had no effect on blood pressure but some girls who consumed up to 3,500 mg of sodium per day had lower blood pressure than those who consumed 2,500 mg daily. Of course, bananas are well known for their high potassium, although foods like avocados, sweet potatoes, yogurt and spinach have even more potassium.

The recommended daily intake of potassium is 4,700 mg per day, but few of us actually manage to even get close to that – that’s about 14 bananas or 3 kilograms (6.6 pounds) of yogurt. However, we tend to eat much more sodium than we should – most Americans consume about 3,400 mg of sodium a day according to data from the American Heart Association. This is more than twice as much as the recommended 1,500 mg / day guideline.

What does this all mean? Well, it doesn’t mean that salt is or isn’t bad for you in total, just that it doesn’t seem to do much for your blood pressure, while potassium seems to be good for your blood pressure, according to this study. Less fast food, more bananas and yogurt!

The findings were published in the journal JAMA Pediatrics.

Developing antimony nanocrystals for better batteries

Researchers from ETH Zurich and Empa have for the first time succeeded in creating uniform antimony nanocrystals. These nanocrystals are able to store a large number of both lithium and sodium ions, operating at a very high rate – in normal English, this means that they can potentially be used as alternative anode materials in future high-energy-density batteries.

Antimony.

Antimony.

Antimony (also called Stibium) is a chemical element generally found with sulphur, in a mineral called stibnite. A lustrous gray metalloid, its compounds have been known since the Antiquity, and were mostly used for cosmetics. However, now, it has more technical uses and its alloys are used in solders, bullets, plain bearings, and more recently, microelectronics.

But with the hunt for better batteries in full stride, researchers now believe they can also use it to one day replace today’s lithium ion batteries. Today, the latter are commonplace and provide power for virtually all electronics, including laptops, smartphones and tables.

The first problem with lithium ion batteries is that, well, lithium is starting to run out. The ever increasing use of electronics has led to a higher than ever lithium requirement, and scientists are already starting to worry. This is why conceptually identical technology based on sodium-ions will receive increasing attention in coming years. However, while lithium batteries have been used and researched for decades, not so much is known about materials which can efficiently store sodium ions. If this were to be figured out, then the way would be paved for the new generation of batteries.

TEM image (false coloured) of monodisperse antimony nanocrystals. (Photo: Maksym Kovalenko Group / ETH Zurich)

TEM image (false coloured) of monodisperse antimony nanocrystals. (Photo: Maksym Kovalenko Group / ETH Zurich)

The team of researchers from ETH Zurich and Empa headed by Maksym Kovalenko may have come a step closer to identifying alternative battery materials: they have become the first to synthesise uniform antimony nanocrystals; the special properties of the nanocrystals makes them ideal candidates for an anode material for both lithium-ion and sodium-ion batteries.

Initial electrochemical tests showed that electrodes made of these antimony nanocrystals perform equally well in sodium and in lithium ion batteries – which makes it even more interesting. Another important outcome of this study is that as long as they’re non the nanoscale, the performance is not really size-dependent. They showed that everywhere in the size-range of 20 to 100 nanometres the material shows excellent, size-independent performance, both in terms of energy density and rate-capability. This is very economically significant.

“This greatly simplifies the task of finding an economically viable synthesis method”, Kovalenko says. “Development of such cost-effective synthesis is the next step for us, together with our industrial partner.” Experiments of his group on monodisperse nanoparticles of other materials show much steeper size-performance relationships such as quick performance decay with increasing the particle size, placing antimony into a unique position among the materials which alloy with lithium and sodium.

However, before we get too excited about this prospect, it has to be said that we’re still several years away from actually seeing this hitting the shelves. It will be another decade or so before a sodium-ion battery with antimony electrodes could hit the market, the ETH-Zurich professor estimates – and there are few groups currently studying it.

“However, other research groups will soon join the efforts,” the chemist is convinced.

Reference: Antimony nanocrystals for batteries