A joint research venture between the University of Birmingham and private firms NitroPep Ltd and Pullman AC has produced air filters that are highly effective at killing bacteria, fungi, and viruses, including the SARS-CoV 2 virus, the infamous coronavirus.
The secret of these filters’ effectiveness is a chemical called chlorhexidine digluconate (CHDG). This is a potent biocide that can kill pathogens within seconds of coming into contact with them. Air filters coated in this substance can prove to be a powerful tool against airborne pathogens around the world, according to the researchers that designed them.
Removing the gunk
“The COVID-19 pandemic has brought to the forefront of public consciousness the real need for new ways to control the spread of airborne respiratory pathogens. In crowded spaces, from offices to large indoor venues, shopping malls, and on public transport, there is an incredibly high potential for transmission of COVID-19 and other viruses such as flu,” says Dr. Felicity de Cogan, Royal Academy of Engineering Industry Fellow at the University of Birmingham, and corresponding author of the paper.
“Most ventilation systems recycle air through the system, and the filters currently being used in these systems are not normally designed to prevent the spread of pathogens, only to block air particles. This means filters can actually act as a potential reservoir for harmful pathogens. We are excited that we have been able to develop a filter treatment which can kill bacteria, fungi and viruses—including SARS-CoV-2—in seconds. This addresses a global un-met need and could help clean the air in enclosed spaces, helping to prevent the spread of respiratory disease.”
The filters were tested in both laboratory and real-life conditions to determine how effective they were at removing air-borne pathogens, and the results are stellar.
In the lab, the filters were covered with viral particles of the Wuhan strain of SARS-CoV-2, alongside control filters. They were then checked periodically over a period of more than one hour to see how these pathogens fared. While much of the initial quantity of viral particles remained on the surface of the control filters for the experiment’s length, all SARS-CoV-2 cells were destroyed within 60 seconds on the treated filters.
Experiments involving bacteria and fungi that commonly cause illness in humans — such as E. coli,S. aureus, and C. albicans— yielded similar results. This showcases the wide applicability of the filters.
To determine how well these fitlers would perform in real-life situations, treated filters were installed in the heating, ventilation, and air conditioning systems on train carriages in the UK alongside control filters in matched pairs on the same train line. These were left to operate for three months before being removed and sent to the lab for analysis — which involved the researchers counting any bacteria colonies that survived on the filters.
No pathogens were found on the treated filters, the team explains. Furthermore, this step showed that the treatment was durable enough to withstand three months of real-world use while maintaining their structure, filtration functions, and anti-pathogen abilities.
“The technology we have developed can be applied to existing filters and can be used in existing heating, ventilation and air conditioning systems with no need for the cost or hassle of any modifications,” Dr. de Cogan explains. “This level of compatibility with existing systems removes many of the barriers encountered when new technologies are brought onto the market.”
NitroPep Ltd is now building on these findings in order to deliver a final marketable version of the coating.
The paper “Efficacy of antimicrobial and anti-viral coated air filters to prevent the spread of airborne pathogens” has been published in the journal Nature Scientific Reports.
About 50% of the world’s food production relies on ammonia fertilizer, an important source of nitrogen that is essential for plant growth. In some fields, it is not uncommon to see 90 kg (200 pounds) of ammonia per acre for each growing season. Elsewhere, ammonia is a valuable ingredient used to make pharmaceuticals, plastics, textiles, explosives, and much more. In other words, ammonia provides an essential service to modern society. There’s just one problem: ammonia production is hugely taxing on the environment, being responsible for about 2% of the global CO2 output. Its carbon footprint is equivalent to all the greenhouse gas emissions released by South Africa.
But that may change since scientists at Monash University in Australia have devised a novel ‘green’ production method for ammonia. To make ammonia today, industrial plants employ what’s known as the Haber-Bosch cycle, during which methane gas is refined to produce hydrogen, which reacts with nitrogen from the atmosphere to synthesize ammonia. In the process, about six tons of carbon dioxide is released for every 1.1 tons of hydrogen.
Besides releasing copious amounts of carbon dioxide that warms the atmosphere, industrial-scale ammonia production also causes nitrate pollution as a byproduct, which often ends up in rivers and groundwater.
The alternative ammonia production method developed at Monash came about while the researchers were focused on an entirely different goal. During the grim 2020 COVID lockdown, researchers Alexandr Simonov and Bryan Suryanto working at the lab of Chemistry professor Doug MacFarlane wanted to make bleach from saltwater using electrolysis — the process of using electricity to split water into hydrogen and oxygen.
This environmentally-friendly bleach could be used to disinfect hospital surfaces while the byproduct alkaline solution is great for handwashing, being kinder to the skin than regular soap. But in the process, the scientists realized that the phosphonium salts they were working with could be precursor chemicals for making ammonia.
Much to their amazement, the researchers were able to “produce ammonia at room temperature, at high, practical rates and efficiency.” No methane – or any kind of fossil fuel for that matter – was involved in the green ammonia synthesis, which can be powered by electricity from renewable energy sources.
This is not the first time that ammonia has been produced from green sources, but the previous effort only yielded small amounts, not enough to be commercially viable at least. In fact, when Suryanto shared the results of the experiments with his colleagues, everyone was dumbfounded.
When Suryanto shared the results of the experiments with his colleagues, everyone was dumbfounded by the excellent output.
“To be honest, the eureka moment was not really ‘Eureka!’, it was more like, ‘Are you sure? I think you need to do that again,’” Professor MacFarlane said in a statement.
“It takes a long time to really believe it. I don’t know that we’ve yet really had a proper celebration. The launch of our spin-out company will possibly be the time that we genuinely celebrate all of this.”
The Monash researchers are currently working with a local company called Jupiter Ionics to bring their ammonia manufacturing method to market.
“The technology opens a broad range of possibilities for future scale-up to very large production facilities for export, attached to dedicated solar and wind farms,” Professor MacFarlane says.
Unlike the huge behemoth industrial plants required to produce ammonia at scale with the Haber-Bosch technique, the new method can produce green ammonia at much smaller plants.
“You don’t need a huge chemical engineering setup. They can be as small as a thick iPad, and that could make a small amount of ammonia continuously to run a commercial greenhouse or hydroponics setup, for example,” Professor MacFarlane said.
“It means that the distributed production of fertilizers becomes possible because the ammonia manufacturing unit is so small and simply constructed,” he added.
Ammonia is obviously coveted in agriculture, but it can also just well double as fuel in transportation. A lot of attention is given to fuel cells that use hydrogen to power vehicles, but ammonia is safer because it’s less combustible and it’s much easier to store than the lightest molecule in the universe that has a tendency to easily escape from tanks. Ammonia’s biggest downside, though, is that it is an important source of nitrogen oxides that is extremely harmful to our health.
Every year, over 1.3 million apples are discarded — but that’s nothing compared to the hundreds of millions of bananas discarded every year. Whatever fruit or vegetable you look at, we discard a lot of it. Food waste is a major global issue, and it’s happening at every level from farm to plate. Globally, up to 40% of all picked fruit is wasted, which is a huge environmental and economic problem.
Some retailers have attempted to solve this problem by packaging fruits in plastic, which keeps them fresh for longer, but created another problem in the form of plastic pollution. But according to some research, there could be another approach that works.
Researchers working at the University of Guelph in Canada have found that they can use hexanal (a compound naturally produced by fruits and veggies) to keep them fresh for a longer period of time. Plants produce hexanal to ward off pests and delay the onset of the enzyme phospholipase D, which makes fruits and veggies go bad.
The researchers used nine different methods of administering the hexanal to fruits, including a spray formulation, a wrap, stickers, and sachets.
“Fruit that is dipped in hexanal after harvest can stay fresh for between three and four weeks longer. This means that fruit can be tree-ripened, picked and shipped to its destinations, where it would arrive in better condition and would contribute to less fruit being discarded as unpalatable or marketable,” the researchers write in an accompanying article.
Mangoes were found to stay fresh for up to three weeks longer, while for nectarines (which are particularly prone to browning), the browning was delayed by nine days.
“We also found that there’s potential for using hexanal to improve the transportation of tastier fruit varieties that are currently too delicate to ship internationally,” write Jayasankar Subramanian and Elizabeth Finnis, two of the researchers involved in the study.
The researchers also emphasize that this could improve the livelihoods of farmers living in impoverished areas. Although they are at the very base of our modern food chain, they often make the least money, and have the least bargaining power. When food gets wasted, it’s often the farmers that end up losing the most.
Hexanal, in spite of its artificial-sounding name, is a natural compound, and it is also safe and approved for consumption. It’s also pretty cheap and production can be scaled easily.
Of course, it will take time (and probably, larger studies) before the use of hexanal can be actually implemented in the agricultural system. But having access to a method that can make produce last longer could end up making an important difference in the world.
An international team of astronomers reports on a new sighting of fluorine in another galaxy. This is the farthest the element has ever been detected and will help us better understand the stellar processes that lead to its creation.
Fluorine is the lightest chemical element in the halogen group, which it shares with other gases such as chlorine. It’s a very reactive element, and in our bodies, it helps give our bones and teeth mechanical strength as fluoride.
New research is helping us understand how this element is formed inside stellar bodies. The study also marks the farthest this element has ever been detected from our galaxy.
From stars to pearly whites
“We all know about fluorine because the toothpaste we use every day contains it in the form of fluoride,” says Maximilien Franco from the University of Hertfordshire in the UK, who led the new study.
“We have shown that Wolf–Rayet stars, which are among the most massive stars known and can explode violently as they reach the end of their lives, help us, in a way, to maintain good dental health!” he adds, jokingly.
The findings were made possible by a joint effort between the Atacama Large Millimeter/submillimeter Array (ALMA) and the European Southern Observatory (ESO), and pertain to a galaxy that’s 12 billion light-years away. The team identified fluorine in the form of hydrogen fluoride as large clouds of gas in the galaxy NGP-190387.
Due to the distance between Earth and NGP-190387, we still see it as it was at only 1.4 billion years old, around one-tenth of the estimated age of the Universe.
Like most of the chemical elements known to us, fluoride forms inside active stars. However, until now, we didn’t know the details of this process, or which stars produced the majority of the fluorine in the Universe.
This discovery helps us better understand how fluorine forms because stars expel chemical elements from their core near to or during the end of their lives. Due to the young age we perceive this galaxy as having from Earth, we can infer that the stars which formed the clouds of hydrogen fluoride must have appeared and died quickly in the grand scheme of things.
Wolf-Rayet stars, very large stellar bodies that only live for a few million years, are the main candidate that the team is considering. They fit the criteria of having short lives, and their size would allow for the huge quantities of hydrogen gas spotted in NGP-190387. Plus, it fits with our previous theories — Wolf-Rayet stars have been suggested as an important source of fluorine in the past, but we didn’t have enough data to confirm this theory, nor did we know how important they were for this process.
Although other processes have been suggested as likely sources of cosmic fluorine, the team believes that they couldn’t account for the time frame involved, nor for the sheer quantity of the element in NGP-190387.
“For this galaxy, it took just tens or hundreds of millions of years to have fluorine levels comparable to those found in stars in the Milky Way, which is 13.5 billion years old. This was a totally unexpected result,” says Chiaki Kobayashi, a professor at the University of Hertfordshire and co-author of the paper. “Our measurement adds a completely new constraint on the origin of fluorine, which has been studied for two decades.”
This is also the first time fluoride has been identified in such a far-away, star-forming galaxy. Since the distances involved in studying the Universe also mean that the further you look, the further back in time you see, it’s also the youngest star-forming galaxy we’ve ever detected fluoride in.
The paper “The ramp-up of interstellar medium enrichment at z > 4” has been published in the journal Nature Astronomy.
However, other types of sunscreen appear to be much more resilient.
Skin cancer is the most common type of cancer in the US (and several other countries). It’s so common that around 1 in 5 Americans will likely develop this form of cancer at some point in their lifetime — which is why it’s so important to wear sunscreen.
A group of researchers from Oregon State University wanted to investigate how different products affect the sunscreen’s ability to do its job after it’s exposed to sunlight.
“Sunscreens are important consumer products that help to reduce UV exposures and thus skin cancer, but we do not know if the use of some sunscreen formulations may have unintended toxicity because of interactions between some ingredients and UV light,” said Tanguay, an OSU distinguished professor and an international expert in toxicology.
The photostability of sunscreens has been shown to be highly dependent on the mixture of the chemicals present, the researchers explain in the study — and zinc isn’t making sunscreen more stable. The team formulated five different ultraviolet-filter (UV-filter) mixtures with an SPF of 15 and analyzed their effect on zebrafish — a widely used model organism that shares many similarities with humans.
“With either size of particle, zinc oxide degraded the organic mixture and caused a greater than 80% loss in organic filter protection against ultraviolet-A rays, which make up 95% of the UV radiation that reaches the Earth,” said Claudia Santillan, one of the study authors. “Also, the zinc-oxide-induced photodegradation products caused significant increases in defects to the zebrafish we used to test toxicity. That suggests zinc oxide particles are leading to degradants whose introduction to aquatic ecosystems is environmentally hazardous.”
“And sunscreens containing inorganic compounds like zinc oxide or titanium dioxide, that block UV rays, are being marketed more and more heavily as safe alternatives to the organic small-molecule compounds that absorb the rays,” Tanguay added.
Tanguay mentions that it’s remarkable that small-molecule mixtures were stable, but it’s unsurprising that adding zinc oxide particles makes sunscreen lose effectiveness and become toxic.
“The findings would surprise many consumers who are misled by ‘nano free’ labels on mineral-based sunscreens that imply the sunscreens are safe just because they don’t contain those smaller particles. Any size of metal oxide particle can have reactive surface sites, whether it is less than 100 nanometers or not. More important than size is the metal identity, its crystal structure and any surface coatings.”
However, this doesn’t mean that you shouldn’t use sunscreen — quite the opposite, sunscreen is one of our most important allies against skin cancer (and nasty skin burns). In addition, there is still some debate within the scientific community about how toxic zinc oxide is to humans, and a 2018 study found that fears are overblown. The main takeaway is that we should be extra careful about what type of sunscreen we use.
“Overall, much more work studying sunscreen formula photostability and phototoxicity is needed to guide design and mass production of safe and effective formulations. Such stability and toxicity studies should inform any sunscreen reformulations, or changes in UV-filter policy, so that regrettable chemical substitutions are avoided,” the study concludes.
The research was published in the journalPhotochemical & Photobiological Sciences.
Purple bacteria are poised to turn your toilet into a source of energy and useable organic material.
Dried sewage sludge. Image credits: Hannes Grobe.
Household sewage and industrial wastewater are very rich in organic compounds, and organic compounds can be very useful. But there’s a catch: we don’t know of any efficient way to extract them from the eww goo yet. So these resource-laden liquids get treated, and the material they contain is handled as a contaminant.
New research plans to address this problem — and by using an environmentally-friendly and cost-efficient solution to boot.
The future is purple (and bacterial)
“One of the most important problems of current wastewater treatment plants is high carbon emissions,” says co-author Dr. Daniel Puyol of King Juan Carlos University, Spain.
“Our light-based biorefinery process could provide a means to harvest green energy from wastewater, with zero carbon footprint.”
The study is the first effort to apply purple phototrophic bacteria — phototrophic means they absorb photons, i.e. light, as they’re feeding — together with electrical stimulation for organic waste recovery. The team showed that this approach can recover up to 100% of the carbon in any type of organic waste, supplying hydrogen gas in return — which is very nice, as hydrogen gas can be used to create power cells or energy directly.
Although green is the poster-color for photosynthesis, it’s far from the only one. Chlorophyll’s role is to absorb energy from light — we perceive this absorption as color. Green chlorophyll, for example, absorbs the wavelengths we perceive as red (which sits opposite green on the color wheel). If you’ve ever toyed around with the color-correction feature in graphical software (a la Photoshop, for example), you know that taking out the reds in a picture will make it look green. The same principle applies here.
Plants are generally green because red wavelengths carry the most energy — and plants need energy to create organic molecules. But the substance comes in all sorts of colors in a variety of different organisms. Phototrophic bacteria also capture energy from sunlight, but they use a different range of pigment — from orange, reds, and browns, to shades of purple — for the job. However, the color itself isn’t important here.
“Purple phototrophic bacteria make an ideal tool for resource recovery from organic waste, thanks to their highly diverse metabolism,” explains Puyol.
These bacteria use organic molecules and nitrogen gas in lieu of CO2 and water as food. This supplies all the carbon, electrons, and nitrogen they need for photosynthesis. The end result is that they tend to grow faster than other phototrophic bacteria or algae and generate hydrogen gas, proteins, and a biodegradable type of polyester as waste.
But what really sealed the deal for the team is that they can decide which of these waste products the bacteria churn out. Depending on environmental conditions such as light intensity, temperature, and the nutrients available, one of these products will predominate in the material they excrete.
The team doubled-down on this property by flooding the bacteria’s environment with electricity.
“Our group manipulates these conditions to tune the metabolism of purple bacteria to different applications, depending on the organic waste source and market requirements,” says co-author Professor Abraham Esteve-Núñez of University of Alcalá, Spain.
“But what is unique about our approach is the use of an external electric current to optimize the productive output of purple bacteria.”
This concept — a “bioelectrochemical system” — works because all of the purple bacteria’s metabolic pathways use electrons as energy carriers. They use up electrons when capturing light, for example. On the other hand, turning nitrogen into ammonia releases electrons, which the bacteria need to dissipate. By applying an electrical current to the bacteria (i.e. by pumping electrons into their environment) or by taking electrons out, the team can cause the bacteria to switch from one process to the other. It also helps improve the overall efficiency of both processes (see Le Chatelier’s principle).
The team included an analysis of the optimum conditions for hydrogen production in the paper (it relies on a mixture of purple bacteria species). They also tested the effect of a negative current (electrons supplied by metal electrodes in the growth medium) on the metabolic behavior of the bacteria.
Their first key finding was that the nutrient blend that fed the highest rate of hydrogen production also minimized the production of CO2 — this would allow the bacteria to recover biofuel from wastewater with a low carbon footprint, the team explains. The negative current experiment proved that these bacteria can use cathode electrons to perform photosynthesis.
Even more striking were the results using electrodes, which demonstrated for the first time that purple bacteria are capable of using electrons from a negative electrode, or “cathode“, to capture CO2 via photosynthesis.
“Recordings from our bioelectrochemical system showed a clear interaction between the purple bacteria and the electrodes: negative polarization of the electrode caused a detectable consumption of electrons, associated with a reduction in carbon dioxide production,” says Esteve-Núñez.
“This indicates that the purple bacteria were using electrons from the cathode to capture more carbon from organic compounds via photosynthesis, so less is released as CO2.”
The paper “Biological and Bioelectrochemical Systems for Hydrogen Production and Carbon Fixation Using Purple Phototrophic Bacteria” has been published in the journal Frontiers in Energy Research.
Glass is associated with brittleness and fragility rather than strength. However, researchers in China were able to create a new transparent amorphous material that is so strong and hard that it can scratch diamonds. What’s more, this high-tech glass has a semiconductor bandgap, which makes it appealing for solar panels.
Strongest amorphous material in the world
Diamond, the hardest material known to date in the universe, is often used in tools for cutting glass. But the tables have turned.
“Comprehensive mechanical tests demonstrate that the synthesized AM-III carbon is the hardest and strongest amorphous material known so far, which can scratch diamond crystal and approach its strength. The produced AM carbon materials combine outstanding mechanical and electronic properties, and may potentially be used in photovoltaic applications that require ultrahigh strength and wear resistance,” the authors of the new study wrote.
The new material developed by scientists at Yanshan University in Hebei province, China, is tentatively named AM-III and was rated at 113 gigapascals (GPA) in the Vickers hardness test. Vickers hardness, a measure of the hardness of a material, is calculated from the size of an impression produced under load by a pyramid-shaped diamond indenter.
That’s more than many natural diamonds that have a Vickers score in the range of 70-100 GPa, but less than the hardest diamonds that can score up to 150 GPa.
It’s about ten times harder than mild steel and could be 20 to 100 times tougher than most bulletproof windows.
Shaped like diamonds, looks like glass
Like diamonds, AM-III is mostly made of carbon. But while carbon atoms in diamond are arranged in an orderly crystal lattice, glass has a chaotic internal structure typical of an amorphous material. This is why glass is typically weak, but AM-III has micro-structures in the material that appear orderly, just like crystals. So, AM-III is part glass, part crystal, which explains its strength.
In order to make AM-III, the Chinese researchers had to employ a process that is even more complicated than manufacturing artificial diamonds. The most common method for creating synthetic diamonds used in the industry is called high pressure, high temperature (HPHT). During HPHT, carbon is subjected to similarly high temperatures and pressure as those that led to the formation of natural diamonds deep in the Earth, around 1,300 degrees Celsius (1650 to 2370 degrees Fahrenheit) and a pressure 50,000 times greater on the surface.
Instead of graphite, the raw material of artificial diamonds, the Chinese researchers started off with fullerene, also called buckminsterfullerene. These molecules contain at least 60 atoms of carbon, commonly denoted as C60, arranged in a lattice that can either form a ball or sphere shape and are typically 1nm diameter.
These carbon “footballs” are typically soft and squishy. But after being subjected to great heat and pressure, the carbon balls are crushed and blended together.
The fullerene was subjected to about 25 GPa of pressure and 1,200 degrees Celsius (2,192 degrees Fahrenheit). However, the researchers were careful to reach these conditions very gradually, taking their time over the course of about 12 hours. Immediately subjecting the material to high pressure and heat may have turned the carbon balls into diamonds.
The resulting transparent material is not only hard but also a semiconductor, with a bandgap range almost as effective as silicon, the main semiconductor used in electronics. So besides bulletproof glass, it could prove useful in the solar panel industry where its properties can shine by allowing sunlight to reach photovoltaic cells, while also enhancing the lifespan of the product.
With enough pressure, you can turn anything into metal, and water is no exception. However, scientists Czech Academy of Sciences in Prague managed to turn liquid water into a bronze-like metallic state without having to apply ungodly amounts of pressure, which makes the achievement all the more impressive.
If squeezed together tightly enough, atoms and molecules can become so compacted in their lattice that they begin to share their outer electrons, allowing them to travel and basically conduct electricity as they would in a copper wire. Case in point, in 2020, French scientists turned the simplest gas in the universe, hydrogen, into a metal and fulfilled a prediction made in 1935 by Nobel Prize laureates Eugene Wigner and Hillard Bell Huntington. Metal hydrogen is, in fact, a superconductor, meaning it conducts electricity with zero electrical resistance.
To do so, the French researchers subjected hydrogen to a staggering 425 gigapascals of pressure — more than four million times the pressure on Earth’s surface, and even higher than that in the planet’s inner core. Therefore, it’s impossible to find metallic hydrogen on Earth, although it may very well be found in Jupiter and Saturn, which are mostly composed of hydrogen gas and have stronger internal pressures than the Earth. Likewise, Neptune and Uranus are believed to host water in a metallic state thanks to their huge pressure.
With the same approach, water would require 15 million bars of pressure to turn it into a metal, more than three times the requirement for metallic hydrogen. That’s simply out of our current technology’s reach. However, there may be another way to turn water metallic without having to squeeze it with the pressure of a gas giant’s core, thought Pavel Jungwirth, a physical chemist at the Czech Academy of Sciences in Prague.
Jungwirth and fellow chemist Phil Mason wondered if water could be coxed to behave like a metal if it borrowed electrons from alkali metals, which are highly reactive elements in the 1st group of the periodic table. They got this idea after previously, Jungwirth and colleagues found that under similar conditions, ammonia can turn shiny.
But despite their willingness to go along with this experiment, the researchers faced a predicament. You see, alkali metals are so reactive in the presence of water that they tend to react explosively.
The solution was to design an experimental setup that dramatically slowed down the reaction so that a potentially catastrophic explosion was averted.
Ironically, the key to mitigating the explosive behavior of the water-alki metal reaction was the adsorbtion of water at very low pressure, about 7,000 smaller than that found at sea level. This setup ensured that the diffusion of the electrons from the alkali metal was faster than the reaction between the water and the metals.
The researchers filled a syringe with an alkali metal solution composed of sodium and potassium, which was placed in a vacuum chamber. The syringe was triggered remotely to expel droplets of the mixture which were exposed to tiny amounts of water vapor.
The water condensed into each droplet of alkali metal, forming a layer over them just one-tenth of a micrometer thick. Electrons from the mixture diffused into the water, along with positive metallic ions, giving the water layer a shiny, bronze-like glow. The entire thing only lasted for a mere couple of seconds, but for all intents of purposes, the scientists had just turned water into metal at room temperature, a fact confirmed by synchrotron experiments.
“We show that a metallic water solution can be prepared by massive doping with electrons upon reacting water with alkali metals. Although analogous metallic solutions of liquid ammonia with high concentrations of solvated electrons have long been known and characterized, the explosive interaction between alkali metals and water has so far only permitted the preparation of aqueous solutions with low, submetallic electron concentrations,” the authors wrote in the journal Nature.
As climate change keeps making our planet hotter and our glaciers melty, scientists report on an unforeseen issue: glacial meltwater from the Greenland Ice Sheet contains high levels of mercury, a toxic heavy metal. According to the report, these levels are comparable to those in rivers where factories dump their waste, creating a major threat to the seafood industry and people who enjoy its products.
It’s never a dull day with environmental woes. A study that began as an effort to analyze the quality of meltwater from the Greenland ice sheet, and how nutrients therein might support coastal wildlife, ended up uncovering very high levels of mercury in the runoff. The finding raises new questions about how global warming will impact wildlife in the region, one of the foremost exporters of seafood worldwide.
“There are surprisingly high levels of mercury in the glacier meltwaters we sampled in southwest Greenland,” said Jon Hawkings, a postdoctoral researcher at Florida State University and the German Research Centre for Geosciences. “And that’s leading us to look now at a whole host of other questions such as how that mercury could potentially get into the food chain.”
Together with glaciologist Jemma Wadham, a professor at the University of Bristol’s Cabot Institute for the Environment, Hawkings initially set out to sample water from three different rivers and two fjords next to the Greenland Ice Sheet. Their aim was to understand how nutrients from glacial meltwater can help to support coastal ecosystems.
Although they also measured for mercury, they didn’t expect to find any meaningful concentrations. Which made the levels of this metal they found in the water all the more surprising.
The baseline for mercury content in rivers is considered to be about 1 to 10 ng / L-1. That’s roughly equivalent to a sand grain of mercury in an Olympic pool of water — so, very low. However, the duo found that mercury levels in the water they sampled were in excess of 150 ng / L-1. Mercury levels in the sediment (called “glacial flour” when it’s produced by glaciers) were over 2000 ng / L-1, which is simply immense.
So far, it remains unclear whether mercury levels drop farther away from this ice sheet, as meltwater gets progressively more diluted. It’s also not yet clear whether the metal is making its way into the marine food web, which would likely make it concentrate further (as animals eat plants and each other).
Although the findings are local, the issue could have global ramifications, as they echo findings in other arctic environments. Greenland is an important producer of seafood, with the export of cold-water shrimp, halibut, and cod being its primary industry. If mercury here does end up in the local food web, it could unknowingly be exported to and consumed by people all over the world.
“We didn’t expect there would be anywhere near that amount of mercury in the glacial water there,” said Associate Professor of Earth, Ocean, and Atmospheric Science Rob Spencer, co-author of the paper. “Naturally, we have hypotheses as to what is leading to these high mercury concentrations, but these findings have raised a whole host of questions that we don’t have the answers to yet.”
“For decades, scientists perceived glaciers as frozen blocks of water that had limited relevance to the Earth’s geochemical and biological processes. But we’ve shown over the past several years that line of thinking isn’t true. This study continues to highlight that these ice sheets are rich with elements of relevance to life.”
Roughly 10% of our planet’s dry land is covered in ice, and the results here raise the worrying possibility that they may be seeping mercury into the waters around them. The issue is compounded by the fact that global warming is making these glaciers melt faster, while we still have an imperfect understanding of how the melting process influences the local geochemistry around them.
So far, the team explains that this mercury is most likely coming from a natural source, not from something like fossil fuel use or industrial activity. While this is very relevant for policy-makers, the fact remains that natural mercury is just as toxic as man-made mercury. If it is sourced from natural processes, however, managing its levels in the wild will be much more difficult to do .
“All the efforts to manage mercury thus far have come from the idea that the increasing concentrations we have been seeing across the Earth system come primarily from direct anthropogenic activity, like industry,” Hawkings said. “But mercury coming from climatically sensitive environments like glaciers could be a source that is much more difficult to manage.”
The paper “Large subglacial source of mercury from the southwestern margin of the Greenland Ice Sheet” has been published in the journal Nature Geoscience.
Transparent wood is getting a citrusy update that’s poised to make it more sustainable, hardier, and even more transparent.
First developed five years ago by researchers at the KTH Royal Institute of Technology, transparent wood is definitely an interesting material. It has many of the characteristics of regular wood (and, indeed, starts out life as such) but it’s generally stronger, more resilient, transparent, and an ok medium to store thermal energy (heat) in.
Now, new research reports how this material can be further improved with a little help from citrus-derived compounds.
Needs some lemon
“The new limonene acrylate it is made from renewable citrus, such as peel waste that can be recycled from the orange juice industry,” says Céline Montanari, a Ph.D. student at the KTH Royal Institute of Technology and lead author of the study.
The process of making transparent wood involves chemically stripping lignin out of wood. Lignin is a natural polymer that plants such as trees use to give their tissues mechanical strength, but it’s also the main light-absorbing compound in there. The empty spaces left over after all this lignin has been removed are later filled in with another transparent compound to restore the material’s strength while allowing light to pass through.
At first, fossil-based polymers (such as synthetic resins) were used for this role. The new paper reports on an alternative to these polymers: limonene acrylate. This is a monomer (individual building blocks of polymers) produced from limonene, which is, in turn, available in the oils found in citrus fruits.
Transparent wood created using the new approach offers much improved optical properties — a “90% optical transmittance” through a plate 1.2 mm thick and a haze of only 30% — the team explains. Unlike other similar composites developed over the last 5 years, transparent wood produced using limonene acrylate is strong enough (and intended to be used) for structural use such as girders or beams. It’s also more sustainable than previous incarnations of the material.
“Replacing the fossil-based polymers has been one of the challenges we have had in making sustainable transparent wood,” Professor Lars Berglund, the head of the KTH’s Department of Fibre and Polymer Technology and corresponding author of the study.
The material requires no solvents to produce, and all the compounds used in the process are derived from biological raw materials. The novel way this material interacts with light further opens new possibilities in fields such as wood nanotechnology, he adds.
“We have looked at where the light goes, and what happens when it hits the cellulose,” Berglund says. “Some of the light goes straight through the wood, and makes the material transparent. Some of the light is refracted and scattered at different angles and gives pleasant effects in lighting applications.”
The team is now hard at work exploring some of these potential applications.
The paper “High Performance, Fully Bio‐Based, and Optically Transparent Wood Biocomposites” has been published in the journal Advanced Science.
Not all water is the same. Most people aren’t aware of the differences but hard water refers to water high in dissolved minerals, such as calcium and magnesium. Soft water, on the other hand, is either rainwater or treated water whose only ion is sodium.
Most groundwater is naturally hard to some extent since it picks up minerals as it percolates through the soil. These include chalk, lime, as well as calcium, and magnesium. If you’d be drinking water from a natural well system, the odds are it will contain hefty amounts of minerals.
Where do you draw the line between hard and soft water?
The answer to the question ‘what exactly is hard water?’ is a matter of mineral concentration, measured in milligrams per liter or grains per gallon.
Each country may have a different standard for what constitutes hard water, but in the United States, the American National Standards defines soft water as containing less than 17.1 mg/L. Although there are different standards in different parts of the world, generally speaking, the following levels be used to assess water hardness:
0-60 mg/L: soft
61-120 mg/L: moderately hard
121-180 mg/L: hard
more than 180 mg/L: very hard
The most common dissolved minerals are calcium and magnesium, both alkaline earth metals found in the 2nd group of the periodic table. These elements have a 2+ charge so they lose two electrons to form cations, such as Ca2+ and Mg2+, which easily dissolve in water.
Leaves deposits of limescale Stains water fixture Can leave clothes discolored
Can contain high levels of corrosive salts Cleans dishes with less water and detergent
Has potential health benefits due to presence of calcium and magnesium Generally tastes better
Can deprive you of vital minerals Has high levels of sodium
My harm hair May trigger eczema Strips skin of surface oils
Lathers soap well Rinses shampoo from hair easier and quicker
Hard water vs soft water.
Which one is better?
It’s not a case where one is better than the other — it all depends on the application. Hard water contains essential minerals that the body needs for the growth and function of bones and muscles, as well as for regulating blood pressure and enzyme action. What’s more, hard water is not only healthier but also tastier, whereas soft water tastes salty. Research supported by the World Health Organization found soft water is unhealthy. So hard water is typically a better option for drinking (although in very high quantities, it’s still not recommended).
In all other instances, hard water is not desirable. Just take a look at your sink, washing machine, and teakettle. If you notice mineral deposits and stubborn white spots that can only be removed with extra scrubbing, hard water is the culprit.
Hard water makes your appliances work hard thereby raising energy bills, causing wear and tear on these appliances, and reducing the lifespan of your plumbing. According to a recent Water Quality Research Foundation study, appliances using soft water have a 30-50% longer life and use 27% less energy. This is why it’s worth investing in the best water softener system — they can be expensive but you actually save money over time by prolonging the lifespan of your washing machine and other appliances.
These undesirable effects are due to the properties of hard water. For instance, when water with a high content of dissolved minerals is heated, it often leaves a coating on pots or containers. That’s because the solution forms calcium carbonate (CaCO3) precipitate.
This precipitate is harmless to human health, but not to that of your appliance. Over time, the build-up constricts the space where water is able to flow, forcing you to replace your dishwasher or plumbing.
To make matters worse, hard water also interferes with cleaning. For instance, the Ca2+ and Mg2+ ions interfere with the surfactant qualities of soap, which means you need to use more laundry or cleaning agents to finish the job properly.
Clothes laundered with hard water can get discolored by a mineral film and can turn stiff and scratchy. Due to the micro-abrasives in hard water, clothes may also fade more quickly and wear out faster.
Hard water can ruin your skin
Besides appliances and plumbing, hard water can also take a toll on skin and hair. When shampoo and soap come in contact with calcium and magnesium ions, the chemical reaction leaves a residue on your skin. Over time, this skin residue can clog up pores, which, in turn, can lead to acne and exacerbate skin conditions like eczema and dermatitis.
Hard water can also affect the skin on your scalp, making it dry and itchy. This is especially true for those with sensitive skin, such as those with psoriasis and eczema. For those with really sensitive skin, even laundering clothes in hard water can irritate the skin.
If you travel somewhere else for a week and notice a significant improvement in your skin, there’s a high chance that your water back home is to blame. In this case, fitting a good mineral filter for your faucet and showerhead is desirable.
How to tell if your water supply is hard or soft
Water hardness test kits. You can directly test your water quality using a number of affordable options, from services that test for hundreds of substances, to simple dip-in, instant read strips.
Warning signs. If you see white scaling on your faucets, if glasses come out of the dishwasher covered in cloudy film, or if you have trouble rinsing off soap and suffer chronic dry skin, you may have hard water.
The soap test. This DIY test works wonders. Fill a glass halfway with water and add soap. Cover the top and give it ashake. If the glass has hard water, the water will be cloudy with minimal suds. If it’s soft, the water will be mostly clear, bu the top will be filled with bubbles.
In the end, hard water can lead to expensive repairs and can dramatically shorten appliance life. Hard water is great for drinking, whereas soft water is the better agent for other household uses.
The toaster-sized experimental MOXIE instrument aboard the rover extracted oxygen from Martian carbon dioxide. It’s only a proof of concept, but it’s an important one, as it suggests that one day Martian astronauts could make their own oxygen for breathing and rocket fuel.
A tree on Mars
The atmosphere of Mars is very different from that of Earth. It’s much thinner (about 96% thinner) and also has a different chemical make-up: it’s poor in oxygen and rich in carbon dioxide. Future astronauts won’t have much use for carbon dioxide, but pure oxygen is a different matter.
“When we send humans to Mars, we will want them to return safely, and to do that they need a rocket to lift off the planet. Liquid oxygen propellant is something we could make there and not have to bring with us. One idea would be to bring an empty oxygen tank and fill it up on Mars,” says Michael Hecht, Principal Investigator of the Perseverance project.
Researchers have been working on ways to do this for a while, and with the Perseverance rover, they got a chance to actually try it out — not in a lab on Earth, but right on Mars.
The MOXIE instrument aims to help humans explore Mars by making OXygen. It works “In situ” (in place) on the Red Planet, and is an Experiment.” As always, NASA loves to toy with acronyms, but the instrument did its job excellently so far.
MOXIE’s first run produced 5.4 grams of oxygen in an hour. The power supply used for the experiment limits potential production to 12 g/hr — about the same amount that a large tree would produce. It’s not spectacular, but it’s the first time this has ever been done, and it could also be scaled up .
“This is a critical first step at converting carbon dioxide to oxygen on Mars,” said Jim Reuter, associate administrator STMD. “MOXIE has more work to do, but the results from this technology demonstration are full of promise as we move toward our goal of one day seeing humans on Mars. Oxygen isn’t just the stuff we breathe. Rocket propellant depends on oxygen, and future explorers will depend on producing propellant on Mars to make the trip home.”
The conversion process requires high levels of heat: 1,470 degrees Fahrenheit (800 Celsius). To withstand these temperatures and carry out the process safely, MOXIE is built from heat-tolerant materials, including 3D-printed nickel alloys and a light aerogel that acts as a buffer, holding the heated air inside. MOXIE is coated with a thin gold layer that reflects infrared heat and ensures that it won’t damage other parts of Perseverance.
Live off the land
This bodes well for future Mars missions, as transporting oxygen all the way there would be quite a hassle. Oxygen tends to take a lot of space, and it’s very unlikely that astronauts to Mars will be able to carry their own oxygen. Extracting oxygen from the Martian soil or atmosphere will therefore be crucial for future missions.
To get a team of four astronauts off of Mars, a future mission would require about 15,000 pounds (7 metric tons) of rocket fuel and 55,000 pounds (25 metric tons) of oxygen. Astronauts that would carry experiments and potentially spend a lot of time on the Red Planet would also require oxygen (though far less than this). With instruments like MOXIE, they could live off the land — quite literally.
“MOXIE isn’t just the first instrument to produce oxygen on another world,” said Trudy Kortes, director of technology demonstrations within STMD. It’s the first technology of its kind that will help future missions “live off the land,” using elements of another world’s environment, also known as in-situ resource utilization.
“It’s taking regolith, the substance you find on the ground, and putting it through a processing plant, making it into a large structure, or taking carbon dioxide – the bulk of the atmosphere – and converting it into oxygen,” she said. “This process allows us to convert these abundant materials into useable things: propellant, breathable air, or, combined with hydrogen, water.”
Now that the technology demonstration was successful, NASA will attempt to extract oxygen at least nine more times over the next two years (Earthly years, that is). The goal is to test the equipment in different conditions to see if it keeps working properly.
Meanwhile, Perseverance will continue its mission to search for signs of microbial life on Mars, analyzing its geology and past climate, as well as paving the way for human exploration.
Times are tough for everybody — but are they ‘recycle our anesthetics’ tough? A team of researchers says yes.
Healthcare can be an important source of greenhouse gas emissions. It accounts for around 5% of all emissions in the UK, for example, or around 10% for the US, a new study from the University of Exeter explains. Inhaled general anesthetics make up a significant part of that, as they are potent greenhouse compounds and very little of them are broken down in the bodies of patients.
The authors explain that recycling these substances can thus have a meaningful and beneficial effect on the climate. An hour-long administration of two common anesthetics, sevoflurane and desflurane, produce around 1.5 and 60kgs of carbon dioxide equivalent, they add. However — these figures don’t take into account emissions from the anesthetics’ manufacturing process, meaning the total figures are much higher.
Running on fumes
What the authors propose is that inhalable anesthetics would be recycled after every use. This would both limit their greenhouse effect in the atmosphere and reduce emissions from manufacturing as lower quantities would be needed overall. They suggest doing this through the use of new vapor-capture technology to harvest, purify, and eventually remarket the anesthetics.
“Our results are an important step in supporting healthcare providers to reduce their carbon footprint. To reduce the carbon footprint of inhalational anesthetics, this study encourages the continued reduction in the use of nitrous oxide and recommends a wider adoption of anesthetic recycling technology,” said lead author Dr. Xiaocheng Hu, of the University of Exeter Medical School.
The study builds on previous analyses around the carbon footprint of inhalable anesthesia including sevoflurane, isoflurane and desflurane, the footprint associated with the use of nitrous oxide, and the carbon footprint of injectable anesthetic Propofol.
Modeling (using typical gas combinations used for anaesthesia in the UK) revealed that sevoflurane and propofol have roughly similar footprints. This likely comes down to the fact that sevoflurane is generally administered mixed with oxygen through a recycling feed. When taking into account their manufacturing processes, however, the carbon footprint of sevoflurane was much higher, similar to that of desflurane. The authors add that nitrous oxide has a disproportionately high effect on the total carbon footprint of anesthesia.
The carrier gases these compounds are delivered in also have an important effect on their final carbon footprint. An air-oxygen mix, according to the team, produces fewer emissions than nitrous oxide. The research showcases why it’s important to consider manufacturing processes as well when calculating a good’s environmental impact. It also goes to show that, at least as far as aesthetics are concerned, this has been underestimated so far.
At the same time, such research might usher in the age of recycled anesthetics — which sounds a bit strange. But hey, if it helps the polar bears, I’ll take it. It’s not like I’m going to feel any difference.
The paper “The carbon footprint of general anaesthetics: A case study in the UK” has been published in the journal Resources, Conservation and Recycling.
Everyone likes sweets. It’s an evolved response to make us seek energy-dense sugars in the wild and eat as much as possible of it. But we’ve also learned that too much sugar can be bad for you, so we’ve developed a hack: sweets our bodies can’t metabolize. All the taste, none of the calories. Which is quite amazing.
So today, let’s take a look at how we’ve managed to hijack one of the most central drives of any living thing, that of feeding themselves, to give ourselves a whole lot of enjoyment while doing almost no ‘feeding’ at all. One very good example of this is sucralose.
So how exactly do you make something sweet that contains zero calories? The wording here is key: it’s not that sucralose doesn’t have any calories — it’s just that you can’t have them. Not most of them, anyway.
Our bodies obtain energy from food by breaking down the chemical bonds which hold it together. Part of what we eat is excreted through the process of digestion, however, because there’s a limit to what our metabolism can process. Certain bonds are either too energy-poor to warrant processing, or just beyond our metabolism’s ability.
Sucralose starts its life as sucrose (sugar) but is transformed through a chemical process. Three oxygen-hydrogen pairs in the sugar molecule are replaced with chlorine atoms. This tiny change makes sucralose pass unprocessed and unabsorbed through our body, essentially locking away the calories it contains. According to the US Food and Drug Administration (FDA), sucralose is actually 600 times as sweet as sugar, and that it can be used “virtually anywhere sugar is used, including cooking and baking” due to its chemical stability.
While its lack of caloric content makes sucralose useful as a sweetener in ‘diet’ items such as gum, cakes, or sodas, arguably its most important use is for diabetics. Sucralose has no effect on a consumer’s carbohydrate metabolism, insulin secretion, or blood glucose levels, so it can be safely consumed by such individuals without health risks (unlike sugar). Due to its high chemical stability, it can be used for alternatives to a wide range of products. Because it doesn’t actually do much in the body, it’s also safe to use as a sweetener for medicine. The commercial name for sucralose is “Splenda”.
Now do note: sucralose is calorie-free, but in its final form, it still contains some calories. This comes down to the fillers used to give it a sugar-like texture and appearance (usually these additives are maltodextrin or dextrose).
How did we get it?
Sucralose was first discovered in 1976 through a cooperation between Queen Elizabeth College and Tate & Lyle, PLC. Folk wisdom has it that it was actually an accident, as a researcher misread the word ‘test’ for ‘taste’ and actually tasted the compound. Which you should never do lightly in a lab setting.
The FDA approved its use for 15 food categories in 1998 and as a wide-range sweetener back in 1999.
Is it safe?
“Sucralose has been extensively studied and more than 110 safety studies were reviewed by FDA in approving the use of sucralose as a general-purpose sweetener for food,” the FDA explains.
Furthermore, the FDA determined that the acceptable daily intake (ADI) level for sucralose and four other “high-intensity sweeteners” would not be exceeded even by “high consumers”, meaning you’re extremely unlikely to go over this limit. This ADI is the quantity of a substance that is deemed safe even for an individual that would consume it every day over the course of their entire lifetime, and it takes into account pregnant or lactating women.
For sucralose, this ADI is 5 mg/kg of body weight/day, roughly translating to 165 packets per day for your average person.
That being said, there is (still limited) evidence that sucralose can negatively impact the microbial communities living in the gut, at least in mice, leading to increased inflammation in the intestines and liver. This doesn’t necessarily mean that humans will see the same effect (not every biological process translates well between species), but it isn’t the most encouraging finding, either.
Long-term inflammation can promote obesity and other health issues. At the same time, while sucralose is used in ‘diet’ food items, some critics have raised the concern that in some cases it may end up making us put on more weight than regular sugar, as individuals might learn to worry less about their sugar intake and thus consume more calories overall.
Finally, while sucralose doesn’t influence blood sugar levels in the general population, at least one study found that obese people who don’t normally consume artificial sweeteners reacted differently. For them, sucralose consumption did lead to elevated blood sugar and insulin levels. However, I haven’t been able to find any follow-up research on this topic.
One area, at least, where we know that sucralose is hands-down better than regular sugar is tooth health. The bacteria in our mouths have as hard a time processing it as our own bodies, so it does ‘starve them out’ to an extent and limit tooth decay. That doesn’t mean you can chow down on endless sucralose cupcakes and have perfect teeth, there are other ingredients in there that still promote tooth decay and you still need to care for them. But it’s less of an impact than that of regular sugar. Sucralose is often used as a sweetener in toothpaste because of this.
For now, while we don’t have everything tied down, we’re very confident that most people can consume sucralose over the long term without any adverse effects. Still, public health institutions around the world strongly advise that if you believe consumption of such sweeteners affects your health you should stop your intake and talk to a doctor. It pays to be safe.
Today, Enewetak is a peaceful circular atoll in the Ralik Chain of the Marshall Islands in the South Pacific. But on the 1st of November, 1952, devastation replaced tranquility after the United States detonated an atomic bomb over the chain of small coral islands.
The test went as planned, with the bomb exploding with a force that was about 500 times more destructive than the Nagasaki blast that suddenly ended the war with the Japanese almost a decade prior. What was surprising was the discovery of a new element in the fallout material that was sent to Berkeley in California for analysis. This new element, known as Einsteinium after physicist Albert Einstein, occupies the 99th position in the periodic table and its properties have always been somewhat elusive — until now.
A completely artificial atomic element
In a new study published in the journal Nature, researchers Berkeley National Laboratory in California used state of the art synthesis and analysis methods to reveal new insights about the physical and chemical properties of this rare heavy element.
Before this assessment, scientists knew that einsteinium has an atomic number of 99, placing it in the same actinide row as uranium. Other than that, there wasn’t much known about Einsteinium due to it being difficult to create and its dangerously high radioactivity.
The researchers worked with less than 250 nanograms of the heavy element, which was manufactured at the Oak Ridge National Laboratory’s High Flux Isotope Reactor, one of the few places in the world capable of synthesizing einsteinium. Specifically, they analyzed einsteinium-254, one of the more stable isotopes of the element that has a half-life of 276 days, compared to a half-life of just 20 days for the more common isotope einsteinium-253. It’s because of this short half-life that we never see einsteinium in nature, even if it was present during Earth’s formation.
As you might imagine, working with einsteinium wasn’t easy. The researchers had to overcome a number of setbacks, including contamination with californium, which is the 98th element, and delays due to the pandemic.
The solution was to bond the heavy radioactive metal with organic molecules called ligands, which acted as a luminescent antenna. After placing the einsteinium sample in a specialized container, the researchers beamed X-rays through it so they could measure the resulting spectrum.
This led to the discovery of the bond distance of einsteinium, a crucial property responsible for how metallic atoms bind to molecules. Along with other aspects of the elusive element’s physical chemistry, these new insights may inform subsequent research and investigations. There is no current ‘practical’ use for einsteinium, but that may be set to change.
The very edge of the periodic table is still terra incognita so there are many things to learn, some fundamental to our understanding of physics and chemistry.
Samples from this Ancient Roman pier, Portus Cosanus in Orbetello, Italy, were studied with X-rays at Berkeley Lab. Credit: J.P. Oleson.
Almost 2,000 years ago, famed Roman historian Pliny the Elder wrote in his Naturalis Historia about the concrete poured in harbors that “as soon as it comes into contact with the waves of the sea and is submerged, becomes a single stone mass, impregnable to the waves and every day stronger.”
This insight is surprisingly spot on, according to a 2017 study that found seawater is the secret ingredient that makes Roman concrete extremely durable by encouraging the growth of rare minerals.
Concrete in some Roman piers is not only still viable today but stronger than it ever was, whereas modern marine concrete structures made from Portland cement crumble within decades.
The ancient Romans used concrete everywhere, particularly in their mega-structures like the Pantheon and Trajan’s Markets in Rome. They would make the concrete by first mixing volcanic ash with lime and seawater to make mortar, which is later incorporated into chunks of volcanic rock, the ‘aggregate’. The combination produces a so-called pozzolanic reaction, so named after the city of Pozzuoli in the Bay of Naples. Another common naturally reactive volcanic sand used for manufacturing concrete is called harena fossicia. It’s thought that Romans might have first gotten the idea for this mixture after observing naturally cemented volcanic ash deposits called tuff.
After the fall of the Roman empire, the recipe for making concrete was lost and a concrete of equal worth wasn’t re-invented until 1824 when an Englishman named Joseph Aspdin discovered Portland cement by burning finely ground chalk and clay in a kiln until the carbon dioxide was removed. It was named “Portland” cement because it resembled the high-quality building stones found in Portland, England.
The ancient Roman recipe is very different than the modern one for concrete, though. Most modern concrete is a mix of Portland cement — limestone, sandstone, ash, chalk, iron, and clay, among other ingredients, heated to form a glassy material that is finely ground — with so-called “aggregates.” These aggregates, usually sand or crushed stone, are not intended to chemically react because if they do, they can cause unwanted expansions in the concrete.
Outliving empires: Roman concrete
University of Utah geologist Marie Jackson’s interest in Roman concrete was sparked by a sabbatical year in Rome where she studied tuffs and volcanic ash deposits. One by one, she approached the factors that made architectural concrete in Rome so resilient. One such factor, she says, is that the mineral intergrowths between the aggregate and the mortar which prevent cracks from lengthening, while the surfaces of nonreactive aggregates in Portland cement only help cracks propagate farther.
While studying drilled cores of Roman harbor concrete, Jackson and colleagues found an exceptionally rare mineral, aluminous tobermorite (Al-tobermorite) in the marine mortar. The mineral’s presence surprised everyone because it is very difficult to make. For Al-tobermorite to form, you need very high temperature. “No one has produced tobermorite at 20 degrees Celsius,” she says. “Oh — except the Romans!”
Seeing how Jackon is a geologist, though, she immediately realized that the mineral must have appeared later. The team concluded with experiments backing them up that seawater percolated through the concrete in breakwaters and in piers, dissolving components of the volcanic ash and allowing new minerals to grow from the highly alkaline leached fluids, particularly Al-tobermorite and phillipsite, the latter being a related zeolite mineral formed in pumice particles and pores in the cementing matrix. In rare instances, underwater volcanoes, such as the Surtsey Volcano in Iceland, produce the same minerals found in Roman concrete.
“We’re looking at a system that’s contrary to everything one would not want in cement-based concrete,” she says. “We’re looking at a system that thrives in open chemical exchange with seawater.”
The Roman concrete samples were studied using a technique called X-ray microdiffraction at UC Berkeley Lab’s ALS. The machine produces beams focused to about 1 micron or about a hundred times smaller than what can be found in a conventional laboratory.
“We can go into the tiny natural laboratories in the concrete, map the minerals that are present, the succession of the crystals that occur, and their crystallographic properties. It’s been astounding what we’ve been able to find,” Jackson said.
This microscopic image shows the lumpy calcium-aluminum-silicate-hydrate (C-A-S-H) binder material that forms when volcanic ash, lime, and seawater mix. Platy crystals of Al-tobermorite have grown amongst the C-A-S-H cementing matrix. Credit: Marie Jackson.
The concrete industry was valued at $50 billion in 2015 in the United States alone. That year, 80 million tons of Portland cement were made or roughly the weight of about 90 Golden Gate Bridges or 12 Hoover Dams. Given the durability of Roman concrete and the substantial carbon dioxide emissions resulting from Portland cement manufacturing, why aren’t we doing it more like the Romans?
It’s not that easy at all, says Jackson. The Romans were quite fortunate to find volcanic ash in their vicinity. Also, the ingredients for their concrete recipe can’t be adapted anywhere in the world. “They observed that volcanic ash grew cements to produce the tuff. We don’t have those rocks in a lot of the world, so there would have to be substitutions made,” Jackson said.
Additionally, Roman concrete takes time to develop strength from seawater and has less compressive strength than typical Portland cement.
Nevertheless, Jackson is closely working with colleagues to make an alternative recipe based on local materials from the western U.S., including seawater from Berkeley, California. Jackson is also leading a scientific drilling project to study the production of tobermorite and other related minerals at the Surtsey volcano in Iceland.
This kind of cement could be very useful for some niche applications. For instance, the Roman cement could be employed in a tidal lagoon project meant to harness tidal power, currently planned in Swansea, United Kingdom. To recuperate the cost incurred from building it, the lagoon would have to operate for 120 years.
“You can imagine that, with the way we build now, it would be a mass of corroding steel by that time,” Jackson said.
Unless it’s made of Roman concrete.
Meanwhile, more tests are being carried out to evaluate the long-term properties of marine structures built from volcanic rock and how these fair against steel-reinforced concrete.
“I think people don’t really know how to think about a material that doesn’t have steel reinforcement,” Jackson said.
Few metals throughout history can boast the same desirability as gold. It has served as a hard currency for virtually every civilization that had access to it, fueled exploration and exploitation, and directly underpinned the dominant economic policy (mercantilism) for at least two centuries.
It is, by and large, one of the most valuable and impactful metals humanity has ever used, despite it being quite soft and very shiny. So what exactly made gold so valuable and expensive, and why did various peoples show such interest in beating it into coins? Surprisingly, it’s not so much the properties that gold has, it’s what other elements don’t have. The fact that it’s pretty and shiny also helps, too. So let’s get into it.
Most transactions today involve either a swap of pieces of paper and plastic, or moving some virtual bits from one account to another. It’s quite a fast and convenient way of buying and selling. On the surface, it’s a very simple process: you give me what I want, I give you these colorful squares in exchange, then we both ride off into the sunset.
But if we delve a bit deeper, this transaction is only made possible by a huge and unseen net of systems and institutions working in concert. For starters, both parties in our hypothetical transaction recognize that the currency involved is desirable and holds value — this is guaranteed by the governments that be. Secondly, money is easy to carry around (portability), either physically in our pocket or on a card, and to count. Thirdly, we know, through various means, that the money swapping hands isn’t fake (it has validity) that it is a finite, often limited, resource (scarcity), and that it won’t rot over time (longevity). Finally, we both know that touching the money won’t kill us — it is safe.
Ultimately, what you want in a coin is for it to be a small but dense repository of value so you can carry a lot of purchasing power easily, long-lasting so you can store it and it won’t just waste away, distinctive (so it’s easy to tell it’s the real deal), in limited supply to some extent (either through natural or policy constraints), and safe to handle.
Which brings us neatly to gold. There are around 118 elements on the periodic table, most of them natural, some of them only seen in the lab for fractions of a second at a time. Not many of them are usable for coinage, because not many of them share in those traits listed above. We’ll look at each of the properties above to understand why certain elements just don’t work as money. However, we’ll leave value out for right now, as it’s a very complex concept that we should look at in a later article.
Portability: elements that are gaseous or liquid at room temperature just don’t make for very convenient money. They’re not very portable, as you need a vessel to carry them in; such vessels can break, in which case your life savings might easily go ‘poof’ or literally down the drain. Around 13 chemical elements take the form of a gas (nitrogen, oxygen, the halogen group, and the noble gases) or liquid (bromine and mercury) natively, so we can cross these off the list.
Denominations would also be a bit hard to pull off with fluid currencies. Let’s say that the units of choice in our make-believe economy are flasks of mercury and flasks of chlorine gas to serve as subdivisions. What if I need to pay someone three-and-a-half bottles of mercury and don’t have any change on hand — do I pour some out? How do I measure it accurately? How do I know you didn’t dilute the ‘coin’ with some other compound? This problem only gets worse with gases.
Finally, all materials react to changes in temperature and pressure — but fluids react the most. Any such currency would probably require special storage conditions, to avoid both physical damage to their containers, as well as any possible losses that would be incurred by changes in temperatures. Carrying coins on your person over long distances would be much more difficult in this case.
In regards to validity, gold has the benefit of being, well, golden. It’s the only elemental metal bearing this color, which means that it’s quite hard to fake. Alloys and minerals like bronze, brass, and pyrite can pass for it, to an extent, but other properties can be used to check whether a coin is made of gold or not. Pure gold is very soft for a metal, so much so that people used to bite coins to check for gold — human teeth enamel has a Mohs hardness of 5, while gold has only 2.5, so your teeth can put a dent in a piece of gold, but not in a gold-plated coin. Most other metals in the periodic table, with some noteworthy exceptions such as copper, are silvery-gray in appearance, so they can, to an extent, be substituted for one another in a coin.
Its longevity is the product of gold’s very, very limited chemical reactivity. Noble metals and noble gases aren’t called ‘noble’ because they’re expensive (although, they are), they’re called that because, like nobles of old, they don’t mingle with the great masses, chemically speaking. Even runner-ups silver and copper get degraded over time — silver tarnishes due to reactions with sulphur compounds in our sweat or other sources, and copper develops patina due to oxygen. Gold doesn’t rust, it doesn’t tarnish, and doesn’t get splotches on it because gold will react with almost nothing. It doesn’t get degraded by virtually any acid, or bacteria, or alkaline solution. To sum it up, there’s not much you can do to damage gold short of throwing it into some King’s Water (aqua regia), which is a mixture of several strong acids.
Scarcity and safety are pretty straightforward: gold is very rare, so people can’t get the raw materials to make their own coins and ruin the economy. Because it’s so chemically inert, touching gold won’t kill you. You can even swallow some up and still be OK, as fancy pastry-shops are happy to remind you. For comparison, think of sodium, which literally explodes on contact with water.
An ideal mix of qualities and faults
So far, so good — but we’ve yet to answer ‘why gold?’. Sure, it’s portable and distinctive, but arguably so is copper. Mercury is very distinctive, even if harder to carry around safely, and lead is very dense even if somewhat silvery. Carbon is safe to handle; platinum or uranium is much rarer. What gives?
Well, here we get to the meat of it: gold (and silver to an extent) is uniquely suited to making coins because it has the right proportions of each trait for the time it was used. It’s rare, but not impossible to find and extract. It is supremely long-lasting and safe, easy to verify and carry, easy to work into sanctioned shapes (coins).
Is uranium rarer? Probably — but it’s so rare that we simply didn’t know it existed for the longest time, and it will probably slowly kill you, which is not ideal. Platinum is just as if not less reactive than gold, but it’s way scarcer on Earth, and requires much, much higher temperatures (read: advanced tech and know-how) to extract and process. Carbon is just as safe, but it’s lying around quite literally everywhere, so it’s worthless as coinage. And so on.
Gold imposed itself because it had just the right amount of each of these traits to make it an attractive option. It’s really pretty to look at and shiny, which can only help, as does gold’s softness — allowing for official, state-guaranteed coins to be minted with the proper markings. Silver and copper have established themselves as the runner-up metals for coinage throughout history as they share some of the properties of gold, but not enough to put them on equal footing: silver degrades somewhat and is much less distinctive, while copper degrades and is too abundant to be properly controlled by authorities.
Still, as history has shown, gold is a workable but not ideal medium for an economy. It’s durable and rare enough to be used as a placeholder for value but there’s only a limited amount of gold that’s practically accessible to humanity on Earth. Things will go swimmingly while your economy is small, but, eventually, you mine all the gold out. After that you can’t make more money to accommodate demand, you get deflation (prices drop), the economy grinds to a halt and then there’s riots. Not good.
The reverse of the coin is that you can also have too much gold. It’s a real problem, I assure you, as Spain can attest. After discovering the Americas, Spain set to work becoming ridiculously rich in the 15th and 16th through a combination of exploiting the locals and treasure fleets. These were not named in jest — they were, to the fullest extent of the word, fleets of ships, all laden with treasures, all coming to Spain.
“A single galleon might carry 2 million pesos [1 peso = ~25 grams of silver]. The modern approximate value of the estimated 4 billion pesos produced during the [300-year] period would come to $530 billion or €470 billion (based on silver bullion prices of May 2015),” Wikipedia explains about these fleets.
Part of these treasures were goods including spices, lumber, skins, and all manner of nice, exotic things from the Americas; but a large part was represented by silver and gold, mined for cheap. Europe’s economies at the time were still using gold (and silver to an extent) as their standard currency. This means that prices all over the continent were directly determined by how much each country had in store. Mercantilism, the idea that a country becomes richer by exporting more than it imports and gaining gold (and silver) from its partners would form out of this relationship.
But when you have a metal underpinning your currency, keeping a balance between how much of it you hoard and how productive your economy is becomes vital. To give you an idea of just how important this relationship is, know that Spain quickly became one of the, if not the, richest country in Europe at the time. It had so much money by the end of it that the Spanish crown had been throwing it away with both arms for almost two centuries — paying off their national debt, funding religious wars or naval wars with England, colonization of other continents, expensive building projects, fine imports — and they still couldn’t spend it fast enough.
Spain saw massive levels of inflation by the 17th century, to such an incredible extent that the crown had declared bankruptcy (they were the first royal rulers to ever do so) repeatedly, and there is cause to believe that these levels of high inflation affected the rest of Europe, at least Western Europe. It had so much gold relative to goods and services in its economy that it wasn’t really scarce anymore. Coins lost value, prices went right up, the economy stalled because nobody could afford to buy anything, and merchants couldn’t lower prices without incurring a loss. Then the economy ground to a halt and there were riots. Again — not good.
A word of ending
Gold is, to this day, seen as a solid repository of value. But the inability to control its supply (to either increase or decrease it) when needed shackled governments and rulers in regards to their fiscal policy. Once you link your coinage to gold and silver, your economy is at the mercy of how much of them is available in your area.
In olden, golden times, this wasn’t much of an issue; economies were pretty small, local things that moved quite slowly, had low output, and limited technological ability. Gold’s longevity, scarcity, portability, the fact that it was verifiable and safe to use made it an ideal tender, despite its limited supply. There wasn’t a technological base to design artificial money that had those traits, so we used a naturally occurring substance instead.
Today, although its properties haven’t changed and there’s more gold around than ever, it simply is too restrictive; economies are fast, dynamic, with massive outputs and impressive technical possibilities. In this world, being portable, safe, and long-lasting is not enough to keep up with economic reality — so we switched to something that’s all of that, but only artificially scarce.
Gold’s properties made it ideal for the minting of coins, and I hope you gained a better understanding of just what makes a good coin. I’ve done my best to try and discuss this topic without touching on concepts of market value or price, as they’re a whole different kettle of fish that we may open up soon. But as is always the case, gold has value because people say it has value — for its uses, its looks, or its association with status, wealth, and power.
Organizing chemical elements in a system that makes sense is not an easy feat. We take the periodic table (the bane of many a highschool student) for granted today, but when it was first invented, it was truly groundbreaking. Not only did Russian chemist Dmitri Mendeleev find a way to arrange the elements by their properties, but he even predicted the properties of then-undiscovered elements.
When Mendeleev first published his table in 1869, there were many gaps in it — after all, evidence for the existence of atoms had only recently emerged. So in addition to providing structure to the emerging science of chemistry, the table also helped predict new elements.
In a recent paper, researchers propose a novel way to arrange chemical elements, in a way that would also facilitate the discovery of new materials during our times.
Researchers love arranging and sorting things in an orderly fashion. But in chemistry, this fashion was hard to find. For instance, noble gases (Helium, Neon, Argon, Krypton, Xenon, Radon), have different masses but they’re all noble gasses: odorless, colorless gases that don’t like to react with the ‘commoners’ of the periodic table. So Mendeleev arranged the noble gases one under another to mark this as a vertical similarity.
There are also horizontal similarities. Horizontally, elements are arranged by the number of protons in the nucleus. Between some groups, vertical similarities are more powerful, while other times, horizontal similarities describe the group. That’s why generally, the periodic table is also colored to mark distinctive groups.
It can all a bit confusing, but if you’re trying to arrange all the elements in the known universe, things are bound to get complex.
A new atomic table from Russia
Now, in a new study, researchers thought ‘what if we take this one step further’. One hundred and fifty years after Mendeleev, researchers Zahed Allahyari and Artem Oganov from the Skolkovo Institute of Science and Technology in Moscow built on earlier work to rearrange the periodic table. Instead of using the number of protons, they use two other properties: the atomic radius and a property called electronegativity, which measures the tendency of an atom to attract another atom and share a pair of electrons.
If you use these two properties and merge them together into just one, you get what’s called a Mendeleev Number (or MN). If you then order elements by their MN, you unsurprisingly end up with neighboring chemical elements having a similar MN. But if you take things further and construct the same list for two-element compounds (compounds consisting of two elements), you end up with something like this:
If you have no idea what this means — don’t worry. The table isn’t aimed at chemistry hobbyists or students, but rather at specialized chemists and material science. Just like how Mendeleev’s table predicted the properties of elements, this trippy table predicts the materials’ properties. Properties such as hardness or magnetization are what’s represented here, and that’s what may be useful for material scientists to create new materials.
This could come in handy, for instance, if you’re looking for a substitute for one material (which may be expensive or scarce). You’d just look for something with similar properties and see what may be more readily available or cheaper. You could find alternatives for the rare elements used in batteries or electronics, for instance.
Similar ideas have been debated in the past. For instance, one such table shows the abundance of various elements on Earth and how likely they are to become scarce in the near future.
Ultimately, this shows that tables aren’t just useful for memorizing and structuring things. Similar to how the periodic table paved the way for future discoveries, new tables such as these can help researchers understand and develop the new generation of materials.
In nature, diamonds were formed billions of years ago deep within Earth’s crust under conditions of intense heat and pressure. Typically, diamonds form at depths of around 150-200 kilometers (93-124 miles) below the surface of Earth, where temperatures average 900 to 1,300 degrees Celsius (1650 to 2370 degrees Fahrenheit) and the pressure is around 50,000 times greater on the surface. This is also why diamonds are so coveted — it took millions of years to make them under special conditions.
But now, scientists in Australia are claiming that they can make diamonds in just a couple of minutes — and at room temperature to boot.
Diamonds are forever… but it shouldn’t take that long to make them
Since diamonds are so rare, geologists sought to develop methods to create artificial diamonds. It was only in the 1950s that Swedish and American scientists finally discovered how to convert graphite and molten iron into a synthetic diamond, fulfilling the literary prediction of Jules Verne.
The most common method for creating synthetic diamonds used in the industry is called high pressure, high temperature (HPHT). During HPHT, carbon is subjected to similarly high temperatures and pressures as the carbon that turned into diamonds billions of years ago.
In their new study, physicists at the Australian National University (ANU) and RMIT University in Melbourne described how they created two types of diamonds. One involves diamonds similar to the kind used in jewelry, the other is a harder-than-usual type called Lonsdaleite created by meteorite impacts.
The amazing thing is that both types of diamonds were generated at room temperature, which is a huge achievement, especially for the rare Lonsdaleite variety that is 58% harder than regular diamonds. However, scientists still had to apply immense pressure onto carbon atoms — the equivalent to 640 African elephants balancing on the tip of a ballet shoe.
“The twist in the story is how we apply the pressure,” says ANU Professor Jodie Bradby. “As well as very high pressures, we allow the carbon to also experience something called ‘shear’ – which is like a twisting or sliding force. We think this allows the carbon atoms to move into place and form Lonsdaleite and regular diamond.”
Small slices from the diamonds were cut and then put under the electron microscope so that the researchers could better understand their structure and how they formed. This way, they noticed the materials were formed within bands, which they call “rivers”.
“Our pictures showed that the regular diamonds only form in the middle of these Lonsdaleite veins under this new method developed by our cross-institutional team,” says RMIT’s Professor Dougal McCulloch. “Seeing these little ‘rivers’ of Lonsdaleite and regular diamond for the first time was just amazing and really helps us understand how they might form.”
These artificial diamonds are not meant as jewelry, although there wouldn’t be something wrong to use them in an engagement wrong. Instead, they’re meant for industrial applications where slicing through tough material is required or as protective shielding.
“Lonsdaleite has the potential to be used for cutting through ultra-solid materials on mining sites,” Bradby said in a statement.
A brewery in the Netherlands has become the first business in the world to use iron powder as fuel on an industrial scale.
We tend to think of fire mostly as something that engulfs wood, coal, petrol, and other flammables. It’s practical to do so — those are the things we burn when we need something to burn. But from a chemical point of view, almost everything burns, given the right conditions — including iron.
The Swinkels Family Brewers in the Netherlands has become the first business to use iron as a fuel for industrial application. It worked together with the Metal Power Consortium and researchers at TU Eindhoven to install a cyclical iron fuel system (more on that shortly) at its Brewery Bavaria, which is able to heat up around 15 million glasses of beer a year.
“We are enormously proud to be the first company to test this new fuel on an industrial scale in order to help accelerate the energy transition,” said Peer Swinkels, CEO of Royal Swinkels Family Brewers. “As a family business, we invest in a sustainable and circular economy because we think in terms of generations, not years.”
“We combine this way of thinking with high-quality knowledge in the collaboration with the Metal Power Consortium. Through this innovative technology, we want to make our brewing process less dependent on fossil fuels. We will continue to invest in this innovation.”
Industries typically rely on fossil fuels for all their heat-intensive needs, since these hold a whole lot of energy in a very dense package. Finely-ground iron can serve the same purpose, however. In such a form and at high temperatures, iron burns easily.
Burning is the physical manifestation of a chemical reaction known as oxidation, and we perceive the energy given off by this reaction as light and heat. When iron is burned this way, there is no output of carbon dioxide (since there’s no carbon in iron). The only product is rust. The best part is that this rust, which is basically just iron oxide, can then be turned back into plain iron with the simple application of an electrical current.
In essence, if you use energy from solar, wind, or other clean sources, you can use iron filings as a sort of clean battery that charges with electricity and outputs heat — which is neat!
Other advantages of this system include how cheap and abundant iron is, how easy it is to transport (it doesn’t need to be cooled like hydrogen, for example), its high energy density, and the high temperatures it can output (up to 1,800 °C / 3,272 °F). It also doesn’t spoil and won’t lose its properties even if stored for a long time.
The cyclical iron system installed at Brewery Bavaria handles both the burning and recharging phases of the process. Depending on how energy is fed back into the used iron, it can store up to 80% of the energy input back into the iron fuel, which is comparable to the efficiencies of modern hydrogen-splitting techniques.
“While we’re proud of this huge milestone, we also look at the future,” says Chan Botter, who leads student team SOLID at TU Eindhoven, a group dedicated to the advancement of metal fuels.
“There’s already a follow-up project which aims to realize a 1-MW system in which we also work on the technical improvement of the system. We’re also making plans for a 10-MW system that should be ready in 2024. Our ambition is to convert the first coal-fired power plants into sustainable iron fuel plants by 2030.”
The system Botter talks about would have a theoretical efficiency of around 40%, which isn’t great, but it could prove to be a convenient and flexible way of storing energy, either for later use or for transport to another site. An advantage of this approach would be that our current energy-generation infrastructure can be adapted to use iron quite easily (as all that is changed is the type of fuel used).
It’s not yet clear if it would be economically-viable, but it’s definitely a very exciting idea — at least, I think it is. There’s also something very cool about the idea of burning iron for power.
Here’s a video detailing how the technology would work from TU Eindhoven: