Portable toilets of the ancient Roman world

New research published today in the Journal of Archaeological Science Reports reveals how archaeologists can determine when a pot was used by Romans as a portable toilet, known as a chamber pot.

"Conical pots of this type have been recognized quite widely in the Roman Empire and in the absence of other evidence they have often been called storage jars. The discovery of many in or near public latrines had led to a suggestion that they might have been used as chamber pots, but until now proof has been lacking," says Roger Wilson, a professor in UBC's department of classical, Near Eastern and religious studies who directs the Gerace archaeological project in Sicily where the pot was found.

Archaeologists at the University of Cambridge analyzed crusty material formed on the inside surface of a ceramic pot dating to the fifth century from a Roman villa site in Sicily. Using microscopy to identify intestinal parasites, the team from the Ancient Parasites Laboratory identified the eggs of whipworm, confirming that the vessel had once contained human faeces.

"It was incredibly exciting to find the eggs of these parasitic worms 1,500 years after they'd been deposited," says co-author Tianyi Wang, University of Cambridge, who took part in the microscopy work.

Whipworms are human parasites that are about five centimetres long and live on the lining of our intestines. The eggs they lay get mixed in with the human faeces, and so would be deposited in a chamber pot during use. Minerals from urine and faeces built up in layers on the inner surface of the pot as it was repeatedly used, creating concretions.

"We found that the parasite eggs became entrapped within the layers of minerals that formed on the pot surface, so preserving them for centuries," says co-author Sophie Rabinow, also of the Cambridge team.

This is the first time that parasite eggs have been identified from concretions inside a Roman ceramic vessel and confirms the Gerace pot must have been used to contain human faeces.

Although the measurements of the Gerace chamber pot (31.8 cm high with a diameter of 34cm at the rim) indicate it could have been used for sitting on, it was more than likely used in conjunction with a wickerwork or timber chair under which the chamber pot was set.

Ceramics are one of the most commonplace forms of archaeological artifact recovered from Roman sites. This technique provides a crucial tool enabling researchers to identify pots which had the special purpose of being a chamber pot, distinguishing them from those used as storage jars for food or other materials (although occasional alternative uses of such vessels have been documented).

"The findings show that parasite analysis can provide important clues for ceramic research," says Rabinow.

The technique will only work if at least one of those people who used the chamber pot was infected by intestinal worms. Where such parasites are endemic in the developing world today, more than half of people are infected by at least one type of intestinal parasite. If Romans were infected as commonly, there is high probability that this approach will identify most such vessels as chamber pots if encrusted deposits are preserved.

Piers Mitchell, the parasites expert who led the study in the laboratory, says: "This pot came from the baths complex of a Roman villa. It seems likely that those visiting the baths would have used this chamber pot when they wanted to go to the toilet, as the baths lacked a built latrine of its own. Clearly, convenience was important to them."

Mitchell adds: "Where Roman pots in museums are noted to have these mineralized concretions inside the base, they can now be sampled using our technique to see if they were also used as chamber pots."

The identification of intestinal parasite eggs in chamber pots has the potential to advance our understanding of the sanitation, diet and intestinal health of people in the past.

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Distant galaxies and the true nature of dark matter

At the centre of spiral galaxies -- those near to us but also those billions of light-years away -- there is a vast spherical region made up of dark matter particles. This region has two defining characteristics: a density that is constant out to a certain radius that amazingly expands over time, while the density decreases. This suggests the existence of a direct interaction between the elementary particles that make up the dark matter halo and those that make up ordinary matter -- protons, electrons, neutrons, and photons. We anticipate that this hypothesis is in direct conflict with the current prevailing theory used to describe the universe -- known as Lambda-Cold Dark Matter -- which posits that particles of cold dark matter are inert and do not interact with any other particle except gravitationally.

These important findings have been reported in a new study, recently published in the prestigious Astronomy and Astrophysics journal, that studied a large number of distant galaxies, some seven billion light-years away. The study, conducted by Gauri Sharma and Paolo Salucci from SISSA, together with Glen Van de Ven from the University of Vienna, took a new look at one of the greatest mysteries of modern physics. According to the authors, this new research represents a step forward in our understanding of dark matter, the elusive element in our universe which has been theorised based on its demonstrable effects on heavenly bodies, but which is yet to be directly proven. This is despite any number of targeted astrophysical observations and experiments set up for the purpose in dedicated underground laboratories.

Studying dark matter in distant galaxies

Dark matter makes up approximately 84% of the mass in the cosmos: "Its dominant presence throughout the galaxies arises from the fact that the stars and hydrogen gas are moving as if governed by an invisible element" explains Gauri Sharma. Up until now, attempts to study it have focused on galaxies near to our own: "In this study, however," she explains, "for the first time, we were seeking to observe and determine the distribution of the mass of spiral galaxies with the same morphology of those nearby, but much further away and therefore earlier by some seven billion years. The idea is essentially that these progenitors of spiral galaxies like our own could offer fundamental clues into the nature of the particle at the heart of the mystery of dark matter." Paolo Salucci adds: "By studying the movement of stars in approximately 300 distant galaxies, we discovered that these objects also had a halo of dark matter, and that, by starting out from the centre of a galaxy, this halo effectively has a region in which its density is constant." This trait had already been observed in studies examining nearby galaxies, some of which were also the work of SISSA.

The new research has revealed, however, that this central region had something that was wholly unexpected within the context of the so-called "standard model of cosmology." Sharma says that "as a result of the contrast between the properties of nearby and distant spiral galaxies -- that is, between today's galaxies and their forebears from seven billion years earlier, we could see that not only is there an unexplained region with a constant density of dark matter, but also that its dimensions increase over time as if being subjected to a process of ongoing expansion and dilution." This evidence is very difficult to be explained if the dark matter particles did not interact, as posited in the Lambda-CDM model. "In the research we recently published," says Sharma, "we offer evidence of direct interaction between dark matter and ordinary matter, that over time slowly builds up a region of consistent density from the centre of the galaxy outwards." But there's more.

A slow yet inexorable process

"Amazingly, the above region with constant density expands over time. It's a very slow process, but one that is inexorable" states Salucci. One possible explanation? "The simplest is that, in the beginning, when the galaxy was formed, the distribution of dark matter in the spherical halo was as predicted by the Lambda-CDM theory, with a density peak in the centre. Later on, the galactic disc that characterises spiral galaxies is formed, surrounded by a halo of extremely dense dark matter particles. As time passed, the effect of the interaction that we have posited meant that the particles were captured by the stars or expelled into the outer reaches of the galaxy." This process would create a spherical region of consistent density within the dark matter halo, with dimensions that increase proportionately over time and finally reach those of the galactic stellar disc, as described in the article in "Astronomy and Astrophysics." "The results of the study pose important questions for alternative scenarios that describe dark matter particles (aside from Lambda-CDM), such as Warm Dark Matter, Self-Interacting Dark Matter and Ultra Light Dark Matter" says Sharma.

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Calorie restriction trial reveals key factors in extending human health

Decades of research has shown that limits on calorie intake by flies, worms, and mice can enhance life span in laboratory conditions. But whether such calorie restriction can do the same for humans remains unclear. Now a new study led by Yale researchers confirms the health benefits of moderate calorie restrictions in humans -- and identifies a key protein that could be harnessed to extend health in humans.

The findings were published Feb. 10 in Science.

The research was based on results from the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE) clinical trial, the first controlled study of calorie restriction in healthy humans. For the trial, researchers first established baseline calorie intake among more than 200 study participants. The researchers then asked a share of those participants to reduce their calorie intake by 14% while the rest continued to eat as usual, and analyzed the long-term health effects of calorie restriction over the next two years.

The overall aim of the clinical trial was to see if calorie restriction is as beneficial for humans as it is for lab animals, said Vishwa Deep Dixit, the Waldemar Von Zedtwitz Professor of Pathology, Immunobiology, and Comparative Medicine, and senior author of the study. And if it is, he said, researchers wanted to better understand what calorie restriction does to the body specifically that leads to improved health.

Since previous research has shown that calorie restriction in mice can increase infections, Dixit also wanted to determine how calorie restriction might be linked to inflammation and the immune response.

"Because we know that chronic low-grade inflammation in humans is a major trigger of many chronic diseases and, therefore, has a negative effect on life span," said Dixit, who is also director of the Yale Center for Research on Aging. "Here we're asking: What is calorie restriction doing to the immune and metabolic systems and if it is indeed beneficial, how can we harness the endogenous pathways that mimic its effects in humans?"

Dixit and his team started by analyzing the thymus, a gland that sits above the heart and produces T cells, a type of white blood cell and an essential part of the immune system. The thymus ages at a faster rate than other organs. By the time healthy adults reach the age of 40, said Dixit, 70% of the thymus is already fatty and nonfunctional. And as it ages, the thymus produces fewer T cells. "As we get older, we begin to feel the absence of new T cells because the ones we have left aren't great at fighting new pathogens," said Dixit. "That's one of the reasons why elderly people are at greater risk for illness."

For the study, the research team used magnetic resonance imaging (MRI) to determine if there were functional differences between the thymus glands of those who were restricting calories and those who were not. They found that the thymus glands in participants with limited calorie intake had less fat and greater functional volume after two years of calorie restriction, meaning they were producing more T cells than they were at the start of the study. But participants who weren't restricting their calories had no change in functional volume.

"The fact that this organ can be rejuvenated is, in my view, stunning because there is very little evidence of that happening in humans," said Dixit. "That this is even possible is very exciting."

With such a dramatic effect on the thymus, Dixit and his colleagues expected to also find effects on the immune cells that the thymus was producing, changes that might underlie the overall benefits of calorie restriction. But when they sequenced the genes in those cells, they found there were no changes in gene expression after two years of calorie restriction.

This observation required the researchers to take a closer look, which revealed a surprising finding: "It turns out that the action was really in the tissue microenvironment not the blood T cells," Dixit said.

Dixit and his team had studied adipose tissue, or body fat, of participants undergoing calorie restriction at three time points: at the beginning of the study, after one year, and after two. Body fat is very important, Dixit said, because it hosts a robust immune system. There are several types of immune cells in fat, and when they are aberrantly activated, they become a source of inflammation, he explained.

"We found remarkable changes in the gene expression of adipose tissue after one year that were sustained through year two," said Dixit. "This revealed some genes that were implicated in extending life in animals but also unique calorie restriction-mimicking targets that may improve metabolic and anti-inflammatory response in humans."

Recognizing this, the researchers then set out to see if any of the genes they identified in their analysis might be driving some of the beneficial effects of calorie restriction. They honed in on the gene for PLA2G7 -- or group VII A platelet activating factor acetylhydrolase -- which was one of the genes significantly inhibited following calorie restriction. PLA2G7 is a protein produced by immune cells known as macrophages.

This change in PLA2G7 gene expression observed in participants who were limiting their calorie intake suggested the protein might be linked to the effects of calorie restriction. To better understand if PLA2G7 caused some of the effects observed with calorie restriction, the researchers also tracked what happened when the protein was reduced in mice in a laboratory experiment.

"We found that reducing PLA2G7 in mice yielded benefits that were similar to what we saw with calorie restriction in humans," said Olga Spadaro, a former research scientist at the Yale School of Medicine and lead author of the study. Specifically, the thymus glands of these mice were functional for a longer time, the mice were protected from diet-induced weight gain, and they were protected from age-related inflammation.

These effects occurred because PLA2G7 targets a specific mechanism of inflammation called the NLRP3 inflammasome, researchers said. Lowering PLA2G7 protected aged mice from inflammation.

"These findings demonstrate that PLA2G7 is one of the drivers of the effects of calorie restriction," said Dixit. "Identifying these drivers helps us understand how the metabolic system and the immune system talk to each other, which can point us to potential targets that can improve immune function, reduce inflammation, and potentially even enhance healthy lifespan."

For instance, it might be possible to manipulate PLA2G7 and get the benefits of calorie restriction without having to actually restrict calories, which can be harmful for some people, he said.

Read more at Science Daily

How life came to Earth

Researchers have discovered a new clue in the search for the origin of life by showing that peptides can form on dust under conditions such as those prevailing in outer space. These molecules, which are one of the basic building blocks of all life, may therefore not have originated on our planet at all, but possibly in cosmic molecular clouds.

Chains of amino acids

All life as we know it consists of the same chemical building blocks. These include peptides, which perform various completely different functions in the body -- transporting substances, accelerating reactions or forming stabilising scaffolds in cells. Peptides consist of individual amino acids arranged in a specific order. The exact order determines a peptide's eventual properties.

How these versatile biomolecules came into being is one of the questions about the origin of life. Amino acids, nucleobases and various sugars found in meteoroids, for example, show that this origin could be extraterrestrial in nature. However, for a peptide to be formed from individual amino acid molecules, very special conditions are required that were previously assumed to be more likely to exist on Earth.

The first step requires water, while for the second step, there must be no water

"Water plays an important role in the conventional way in which peptides are created," says Dr Serge Krasnokutski of the Laboratory Astrophysics and Cluster Physics Group of the Max Planck Institute for Astronomy at the University of Jena. In this process, individual amino acids combine to form a chain. For this to happen, one water molecule must be removed each time. "Our quantum chemical calculations have now shown that the amino acid glycine can be formed through a chemical precursor -- called an amino ketene -- combining with a water molecule. Put simply: in this case, water must be added for the first reaction step, and water must be removed for the second."

With this knowledge, the team led by the physicist Krasnokutski has now been able to demonstrate a reaction pathway that can take place under cosmic conditions and does not require water.

"Instead of taking the chemical detour in which amino acids are formed, we wanted to find out whether amino ketene molecules could not be formed instead and combine directly to form peptides," says Krasnokutski, describing the basic idea behind the work. He adds: "And we did this under the conditions that prevail in cosmic molecular clouds, that is to say on dust particles in a vacuum, where the corresponding chemicals are present in abundance: carbon, ammonia and carbon monoxide."

In an ultra-high vacuum chamber, substrates that serve as a model for the surface of dust particles were brought together with carbon, ammonia and carbon monoxide at about one quadrillionth of normal air pressure and minus 263 degrees Celsius.

"Investigations showed that under these conditions, the peptide polyglycine was formed from the simple chemicals," Krasnokutski says. "These are therefore chains of the very simple amino acid glycine, and we observed different lengths. The longest specimens consisted of eleven units of the amino acid."

In this experiment, the german team was also able to detect the suspected amino ketene. "The fact that the reaction can take place at such low temperatures at all is due to the amino ketene molecules being extremely reactive. They combine with each other in an effective polymerisation. The product of this is polyglycine."

Quantum mechanical tunnelling effect might play a role

"It was nevertheless surprising to us that the polymerisation of amino ketene could happen so easily under such conditions," says Krasnokutski. "This is because an energy barrier actually has to be overcome for this to happen. However, it may be that we are helped in this by a special effect of quantum mechanics. In this special reaction step, a hydrogen atom changes its place. However, it is so small that, as a quantum particle, it could not overcome the barrier but was simply able to cross it, so to speak, through the tunnelling effect."

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Planetary bodies observed for first time in 'habitable zone' of dead star

A ring of planetary debris studded with moon-sized structures has been observed orbiting close to a white dwarf star, hinting at a nearby planet in the "habitable zone" where water and life could exist, according to a new study led by UCL researchers.

White dwarfs are glowing embers of stars that have burned through all their hydrogen fuel. Nearly all stars, including the Sun, will eventually become white dwarfs, but very little is known about their planetary systems.

In the study, published in Monthly Notices of the Royal Astronomical Society, an international team of researchers measured light from a white dwarf in the Milky Way known as WD1054-226, using data from ground- and space-based telescopes.

To their surprise, they found pronounced dips in light corresponding to 65 evenly spaced clouds of planetary debris orbiting the star every 25 hours. The researchers concluded that the precise regularity of the transiting structures -- dimming the star's light every 23 minutes -- suggests they are kept in such a precise arrangement by a nearby planet.

Lead author Professor Jay Farihi (UCL Physics & Astronomy) said: "This is the first time astronomers have detected any kind of planetary body in the habitable zone of a white dwarf.

"The moon-sized structures we have observed are irregular and dusty (e.g. comet-like) rather than solid, spherical bodies. Their absolute regularity, one passing in front of the star every 23 minutes, is a mystery we cannot currently explain.

"An exciting possibility is that these bodies are kept in such an evenly-spaced orbital pattern because of the gravitational influence of a nearby planet. Without this influence, friction and collisions would cause the structures to disperse, losing the precise regularity that is observed. A precedent for this 'shepherding' is the way the gravitational pull of moons around Neptune and Saturn help to create stable ring structures orbiting these planets.

"The possibility of a planet in the habitable zone is exciting and also unexpected; we were not looking for this. However, it is important to keep in mind that more evidence is necessary to confirm the presence of a planet. We cannot observe the planet directly so confirmation may come by comparing computer models with further observations of the star and orbiting debris."

It is expected that this orbit around the white dwarf was swept clear during the giant star phase of its life, and thus any planet that can potentially host water and thus life would be a recent development. The area would be habitable for at least two billion years, including at least one billion years into the future.

More than 95% of all stars will eventually become white dwarfs. The exceptions are the largest stars that explode and become either black holes or neutron stars.

Professor Farihi added: "Since our Sun will become a white dwarf in a few billion years, our study provides a glimpse into the future of our own solar system."

When stars begin running out of hydrogen, they expand and cool, becoming red giants. The Sun will enter this phase in four to five billion years, swallowing Mercury, Venus, and possibly Earth. Once the outer material has gently blown away and hydrogen is exhausted, the hot core of the star remains, slowly cooling over billions of years -- this is the star's white dwarf phase.

Planets orbiting white dwarfs are challenging for astronomers to detect because the stars are much fainter than main-sequence stars (like the Sun). So far, astronomers have only found tentative evidence of a gas giant (like Jupiter) orbiting a white dwarf.

For the new study, researchers observed WD1054-226, a white dwarf 117 light years away, recording changes in its light over 18 nights using the ULTRACAM high-speed camera fixed on to the ESO 3.5m New Technology Telescope (NTT) at the La Silla Observatory in Chile. In order to better interpret the changes in light, the researchers also looked at data from the NASA Transiting Exoplanet Survey Satellite (TESS), which allowed the researchers to confirm the planetary structures had a 25-hour orbit.

They found that the light from WD1054-226 was always somewhat obscured by enormous clouds of orbiting material passing in front of it, suggesting a ring of planetary debris orbiting the star.

The habitable zone, sometimes called the Goldilocks zone, is the area where the temperature would theoretically allow liquid water to exist on the surface of a planet. Compared to a star like the Sun, the habitable zone of a white dwarf will be smaller and closer to the star as white dwarfs give off less light and thus heat.

The structures observed in the study orbit in an area that would have been enveloped by the star while it was a red giant, so are likely to have formed or arrived relatively recently, rather than survived from the birth of the star and its planetary system.

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First evidence indicating dinosaur respiratory infection

A group of researchers from around the country, including University of New Mexico Research Assistant Professor Ewan Wolff, discovered the first evidence of a unique respiratory infection in the fossilized remains of a dinosaur that lived nearly 150 million years ago.

Researchers examined the remains of an immature diplodocid -- a long-necked herbivorous sauropod dinosaur, like "Brontosaurus" - dating back to the Late Jurassic Period of the Mesozoic Era. The dinosaur nicknamed "Dolly," discovered in southwest Montana, had evidence of an infection in the area of its neck vertebrae.

They study, led by Cary Woodruff of the Great Plains Dinosaur Museum, identified never before seen abnormal bony protrusions that had an unusual shape and texture. These protrusions were located in an area of each bone where they would have been penetrated by air sacs. Air sacs are non-oxygen exchanging parts of the respiratory system in modern birds that are also present in dinosaurs. The air sacs would have ultimately connected to "Dolly's" lungs and formed part of the dinosaur's complex respiratory system. CT imaging of the irregular protrusions revealed that they were made of abnormal bone that most likely formed in response to an infection.

"We've all experienced these same symptoms -- coughing, trouble breathing, fever and here's a 150-million-year-old dinosaur that likely felt as miserable as we all do when we're sick." Woodruff said.

Researchers say these findings are significant because Dolly was considered a non-avian dinosaur, and sauropods, like Dolly, did not evolve to become birds; only avian theropods evolved into birds. The authors speculate this respiratory infection could have been caused by a fungal infection similar to aspergillosis, a common respiratory illness that affects birds and reptiles today and can lead to bone infections. In addition to documenting the first occurrence of such a respiratory infection in a dinosaur, this fossilized infection also has important anatomical implications for the respiratory system of sauropod dinosaurs.

"This fossil infection in Dolly not only helps us trace the evolutionary history of respiratory-related diseases back in time, but it also gives us a better understanding of what kinds of diseases dinosaurs were susceptible to," Woodruff said.

"This would have been a remarkably, visibly sick sauropod," Wolff said. "We always think of dinosaurs as big and tough, but they got sick. They had respiratory illnesses like birds do today, in fact, maybe even the same devastating infections in some cases."

The researchers suggest that if Dolly had been infected with an aspergillosis-like respiratory infection, it likely experienced flu or pneumonia-like symptoms such as weight loss, coughing, fever and breathing difficulties. As aspergillosis can be fatal in birds if untreated, a potentially similar infection in Dolly could have ultimately caused the death of the animal.

"We have to continue to expand our knowledge of ancient diseases. If we look hard enough, we may begin to understand more about the evolution of immunity and infectious disease," Wolff said. "When we work together between multiple specialties -- veterinarians, anatomists, paleontologists, paleopathologists, and radiologists we can come away with a more complete picture of ancient disease."

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Futuristic coating for hospital fabrics and activewear kills COVID virus and E. coli

UBC researchers have developed an inexpensive, non-toxic coating for almost any fabric that decreases the infectivity of the virus that causes COVID-19 by up to 90 per cent.

And in the future, you might be able to spray it on fabric yourself.

"When you're walking into a hospital, you want to know that pillow you're putting your head onto is clean," says lead author Taylor Wright, a doctoral student in the department of chemistry. "This coating could take a little bit of the worry off frontline workers to have Personal Protection Equipment with antimicrobial properties."

Researchers soaked fabric in a solution of a bacteria-killing polymer which contains a molecule that releases sterilizing forms of oxygen when light shines on it. They then used an ultraviolet (UV) light to turn this solution to a solid, fixing the coating to the fabric. "This coating has both passive and active antimicrobial properties, killing microbes immediately upon contact, which is then amped up when sunlight hits the cloth," says senior author Dr. Michael Wolf (he/him), a professor of chemistry.

Both components are safe for human use, and the entire process takes about one hour at room temperature, says Wright. It also makes the fabric hydrophobic, meaning microbes are less likely to stick to the cloth, and doesn't seem to affect the strength of the fabric.

In addition, the coating can be used on almost any fabric, including cotton, polyester, denim, and silk, with applications in hospital fabrics, masks, and activewear. Whereas other such technologies can involve chemical waste, high energy use, or expensive equipment, the UBC method is relatively easy and affordable, says Wright. "All we need is a beaker and a light bulb. I'm fairly certain I could do the whole process on a stove."

To test the coating's bug-killing properties, the researchers bathed treated fabric in bacterial soups of Escherichia coli (E. coli) andMethicillin-resistant Staphylococcus aureus (MRSA), both major sources of hospital-acquired infections. They found there were 85 per cent of viable E. coli bacteria remaining after 30 minutes, which fell to three per cent when the treated cloth was exposed to green light for the same amount of time. Similarly, 95 per cent of viable MRSA bacteria remained, dropping to 35 per cent under green light. No bacteria remained after four hours.

Given that sunlight or fluorescent lights have a lesser percentage of green, the team expects similar but less intense results for fabric exposed to those light sources, says Wright. "Particularly in the Pacific Northwest, it's not always a sunny day. So, at all times you're going to have that layer of passive protection and when you need that extra layer of protection, you can step into a lit room, or place the fabric in a room with a green light bulb -- which can be found for about $35 online."

The researchers also looked into whether the coating reduced the infectivity of SARS-CoV-2, the virus causing COVID-19 by bathing treated fabric in a solution of the virus particles and then adding that solution to living cells to see if they could infect them. They found the passive properties weren't effective against the virus, but when treated fabric was exposed to green light for two hours, there was up to 90 per cent decrease in the infectivity of SARS-CoV-2. "In other words, only one tenth of the amount of virus signal was detected on cells infected with the UV-fabric and light treated virus," says co-author Dr. François Jean (he/him), professor of virology at UBC. The efficacy of the new fabric against SARS-CoV-2 was demonstrated by Dr. Jean's team at UBC FINDER, the state-of-the-art level three biocontainment facility founded by Dr. Jean in 2010.

The team found they needed an 18 square centimeter piece of fabric to kill microbes with material containing seven per cent weight of the active ingredient, but that increasing this to 23 per cent weight increased the effectiveness of the fabric at four times less material, says Wright.

Researchers also found that keeping the fabric under green light for more than 24 hours failed to produce the sterilizing forms of oxygen, highlighting an area for further study. This is a similar effect to the color fading on clothing after being exposed to sunlight for too long.

Read more at Science Daily

Reusable plastic bottles release hundreds of chemicals

Researchers at the University of Copenhagen have found several hundred different chemical substances in tap water stored in reusable plastic bottles. Several of these substances are potentially harmful to human health. There is a need for better regulation and manufacturing standards for manufacturers, according to the chemists behind the study.

Have you ever experienced the strange taste of water after it has been in a reusable plastic bottle for a while? It appears that there is a solid, yet worrying reason for this.

Two chemists from the University of Copenhagen have studied which chemical substances are released into liquids by popular types of soft plastic reusable bottles. The results were quite a surprise.

"We were taken aback by the large amount of chemical substances we found in water after 24 hours in the bottles. There were hundreds of substances in the water -- including substances never before found in plastic, as well as substances that are potentially harmful to health. After a dishwasher cycle, there were several thousand," says Jan H. Christensen, Professor of Environmental Analytical Chemistry at the University of Copenhagen's Department of Plant and Environmental Sciences.

Endocrine disruptors and insecticide

Professor Christensen and fellow researcher Selina Tisler detected more than 400 different substances from the bottle plastic and over 3,500 substances derived from dishwasher soap. A large portion of these are unknown substances that the researchers have yet to identify. But even of the identified chemicals, the toxicity of at least 70 % remains unknown.

Photo-initiators are among the toxic substances in the water which worry the researchers. These are known to have potentially harmful effects on health in organisms, such as being endocrine disruptors and carcinogens. Furthermore, the researchers found a variety of plastic softeners, antioxidants and release agents used in the manufacture of the plastic, as well as Diethyltoluamide (DEET), commonly known as the active substance in mosquito spray.

Machine washing adds more substances into the bottled water

In their experiments, the researchers mimicked the ways in which many people typically use plastic drinks bottles. People often drink water that has been kept in bottles for several hours. The researchers left ordinary tap water in both new and used drinking bottles for 24 hours, both before and after machine washing, as well as after the bottles had been in the dishwasher and rinsed thoroughly in tap water.

"What is released most after machine washing are the soap substances from the surface. Most of the chemicals that come from the water bottle itself remain after machine washing and extra rinsing. The most toxic substances that we identified actually came after the bottle had been in the dishwasher -- presumably because washing wears down the plastic and thereby increases leaching," explains postdoctoral researcher and first author Selina Tisler of the Department of Plant and Environmental Sciences.

In new reusable bottles, close to 500 different substances remained in the water after an additional rinse. Over 100 of these substances came from the plastic itself.

She emphasizes that they have yet to conclude whether the water in the bottles is harmful to health, as they currently have only an estimate of the concentrations of the substances and toxicological assessments have yet to be completed.

'Just because these substances are in the water, doesn't mean that the water is toxic and affects us humans. But the problem is, is that we just don't know. And in principle, it isn't all that great to be drinking soap residues or other chemicals," says Selina Tisler.

"From now on, I'll use a glass bottle."

"We care so much about low levels of pesticides in our drinking water. But when we pour water into a container to drink from, we unflinchingly add hundreds or thousands of substances to the water ourselves. Although we cannot yet say whether the substances in the reusable bottles affect our health, I'll be using a glass or quality stainless steel bottle in the future," says Jan H. Christensen.

The researchers suspect that bottle manufacturers only add a small proportion of the substances found intentionally. The majority have inadvertently occurred either during the production process or during use, where substances may have been converted from other substances. This includes the presence of the mosquito repellent DEET, where the researchers hypothesize that as one of the plastic softeners degrades, it is converted into DEET.

"But even of the known substances that manufacturers deliberately add, only a tiny fraction of the toxicity has been studied. So, as a consumer, you don't know if any of the others have a detrimental effect on your health," says Selina Tisler.

Too little knowledge, too leniently regulated

According to the researchers, the results reflect a lack of both knowledge and regulation:

"The study exemplifies how little knowledge there is about the chemicals emitted from the products that our food and drink come in contact with. And, it is a general problem that measurement regulations during production are very lenient. Fortunately, both in Denmark and internationally, we are looking into how to better regulate this area," says Jan H. Christensen.

In the meantime, Selina Tisler hopes that companies take responsibility on their own accord:

"Hopefully, companies that put their names on reusable plastic bottles will be more careful about the products they purchase from suppliers and perhaps place greater demands on suppliers to investigate the substances found in what they manufacture," Tisler concludes.

The study results are published in the scientific journal Journal of Hazardous Materials.

Brief summary of experiment

Three different types of drinking bottles were tested, all of which are found in Danish stores. Two of the bottles are made of biodegradable plastic, according to the manufacturer. Both new and heavily used bottles were used. The bottles were tested both before and after machine washing, and after five extra rinses in tap water.

Read more at Science Daily

New planet detected around Proxima Centauri, closest star our solar system

A team of astronomers using the European Southern Observatory's Very Large Telescope (ESO's VLT) in Chile have found evidence of another planet orbiting Proxima Centauri, the closest star to our Solar System. This candidate planet is the third detected in the system and the lightest yet discovered orbiting this star. At just a quarter of Earth's mass, the planet is also one of the lightest exoplanets ever found.

"The discovery shows that our closest stellar neighbour seems to be packed with interesting new worlds, within reach of further study and future exploration," explains João Faria, a researcher at the Instituto de Astrofísica e Ciências do Espaço, Portugal and lead author of the study published today in Astronomy & Astrophysics. Proxima Centauri is the closest star to the Sun, lying just over four light-years away.

The newly discovered planet, named Proxima d, orbits Proxima Centauri at a distance of about four million kilometres, less than a tenth of Mercury's distance from the Sun. It orbits between the star and the habitable zone -- the area around a star where liquid water can exist at the surface of a planet -- and takes just five days to complete one orbit around Proxima Centauri.

The star is already known to host two other planets: Proxima b, a planet with a mass comparable to that of Earth that orbits the star every 11 days and is within the habitable zone, and candidate Proxima c, which is on a longer five-year orbit around the star.

Proxima b was discovered a few years ago using the HARPS instrument on ESO's 3.6-metre telescope. The discovery was confirmed in 2020 when scientists observed the Proxima system with a new instrument on ESO's VLT that had greater precision, the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO). It was during these more recent VLT observations that astronomers spotted the first hints of a signal corresponding to an object with a five-day orbit. As the signal was so weak, the team had to conduct follow-up observations with ESPRESSO to confirm that it was due to a planet, and not simply a result of changes in the star itself.

"After obtaining new observations, we were able to confirm this signal as a new planet candidate," Faria says. "I was excited by the challenge of detecting such a small signal and, by doing so, discovering an exoplanet so close to Earth."

At just a quarter of the mass of Earth, Proxima d is the lightest exoplanet ever measured using the radial velocity technique, surpassing a planet recently discovered in the L 98-59 planetary system. The technique works by picking up tiny wobbles in the motion of a star created by an orbiting planet's gravitational pull. The effect of Proxima d's gravity is so small that it only causes Proxima Centauri to move back and forth at around 40 centimetres per second (1.44 kilometres per hour).

"This achievement is extremely important," says Pedro Figueira, ESPRESSO instrument scientist at ESO in Chile. "It shows that the radial velocity technique has the potential to unveil a population of light planets, like our own, that are expected to be the most abundant in our galaxy and that can potentially host life as we know it."

"This result clearly shows what ESPRESSO is capable of and makes me wonder about what it will be able to find in the future," Faria adds.

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JET fusion facility sets a new world energy record

European scientists have achieved a major success on the road to energy production through fusion plasmas: They produced stable plasmas with 59 megajoules of energy output at the world's largest fusion facility, JET, in Culham near Oxford, UK. The team, which also includes researchers from the Max Planck Institute for Plasma Physics (IPP), used the fuel of future fusion power plants. These were the first experiments of their kind in the world in more than 20 years.

Following the example of the sun, fusion power plants aim to fuse the hydrogen isotopes deuterium and tritium and release large amounts of energy in the process. The only plant in the world currently capable of operating with such fuel is the European joint project JET, the Joint European Torus in Culham near Oxford, UK. However, the last experiments with the fuel for future fusion power plants were conducted there in 1997. Because tritium is a very rare raw material that also poses special handling challenges, research teams usually use hydrogen or deuterium for plasma experiments. In future power plants, tritium will be formed from lithium during energy production.

Experiments with deuterium-tritium mixtures in preparation for ITER

"We can explore the physics in fusion plasmas very well by working with hydrogen or deuterium, so this is the standard worldwide," explains IPP's Dr. Athina Kappatou, who with her IPP colleagues Dr. Philip Schneider and Dr. Jörg Hobirk led significant parts of the European collaborative experiments at JET." However, for the transition to the international, large-scale, fusion experiment ITER, it is important that we prepare for the conditions prevailing there." ITER is currently under construction in Cadarache, in southern France, and is expected to be able to release ten times as much energy as is fed into the plasma in terms of heating energy, using deuterium-tritium fuel.

To bring the JET experiment as close as possible to future ITER conditions, the previous carbon lining of the plasma vessel was replaced by a mixture of beryllium and tungsten, as is also planned for ITER, between 2009 and 2011. The metal tungsten is more resistant than carbon, which, moreover, stores too much hydrogen. However, the now metallic wall places new demands on the quality of the plasma control. The current experiments demonstrate the successes of the researchers: At temperatures ten times higher than those at the center of the sun, record levels of generated fusion energy have been achieved.

World record under ITER-like conditions

Prior to the change of the wall material, JET had set the world energy record in 1997 with a plasma that produced 22 megajoules of energy. This record stood until now. "In the latest experiments, we wanted to prove that we could create significantly more energy even under ITER-like conditions," explains IPP physicist Dr. Kappatou. Several hundred scientists and researchers were involved in years of preparation for the experiments. They used theoretical methods to calculate in advance the parameters they needed to obtain to generate the plasma in order to achieve their goals. The experiments confirmed the predictions in late 2021 and delivered a new world record: JET produced stable plasmas with deuterium-tritium fuel that released 59 megajoules of energy.

To produce net energy -- that is, to release more energy than the heatering systems provide -- the experimental facility is too small. This will not be possible until the larger-scale ITER experiment in southern France comes online. "The latest experiments at JET are an important step toward ITER," concludes Prof. Sibylle Günter, Scientific Director of the Max Planck Institute for Plasma Physics. "What we have learned in the past months will make it easier for us to plan experiments with fusion plasmas that generate much more energy than is needed to heat them."

Background information: Megawatts vs. Megajoules

In the recent record-breaking experiment, the fusion reactions in JET released a total of 59 megajoules of energy in the form of neutrons during a five-second phase of a plasma discharge. Expressed in units of power (energy per time), JET achieved a power output of just over 11 megawatts averaged over five seconds. The previous energy record, set in 1997, was just under 22 megajoules of total energy and 4.4 megawatts of power averaged over five seconds.

About JET

JET was jointly designed and built by the members of the European fusion program EUROfusion and has been jointly operated since 1983. The English fusion center "Culham Centre for Fusion Energy" in Culham near Oxford is responsible for the technical operations, while temporarily seconded researchers and technicians from the EUROfusion laboratories work on the facility on a campaign basis. With numerous secondments, IPP is an important participant in the JET program.

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