Common household chemicals pose new threat to brain health, study finds

A team of researchers from the Case Western Reserve University School of Medicine has provided fresh insight into the dangers some common household chemicals pose to brain health. They suggest that chemicals found in a wide range of items, from furniture to hair products, may be linked to neurological conditions like multiple sclerosis and autism spectrum disorders.

Neurological problems impact millions of people, but only a fraction of cases can be attributed to genetics alone, indicating that unknown environmental factors are important contributors.

The new study published today in the journal Nature Neuroscience, discovered that some common home chemicals specifically affect the brain's oligodendrocytes, a specialized cell type that generates the protective insulation around nerve cells.

"Loss of oligodendrocytes underlies multiple sclerosis and other neurological diseases," said the study's principal investigator, Paul Tesar, the Dr. Donald and Ruth Weber Goodman Professor of Innovative Therapeutics and director of the Institute for Glial Sciences at the School of Medicine. "We now show that specific chemicals in consumer products can directly harm oligodendrocytes, representing a previously unrecognized risk factor for neurological disease."

On the premise that not enough thorough research has been done on the impact of chemicals on brain health, the researchers analyzed over 1,800 chemicals that may be exposed to humans. They identified chemicals that selectively damaged oligodendrocytes belong to two classes: organophosphate flame retardants and quaternary ammonium compounds. Since quaternary ammonium compounds are present in many personal-care products and disinfectants, which are being used more frequently since the COVID-19 pandemic began, humans are regularly exposed to these chemicals. And many electronics and furniture include organophosphate flame retardants.

The researchers used cellular and organoid systems in the laboratory to show that quaternary ammonium compounds cause oligodendrocytes to die, while organophosphate flame retardants prevented the maturation of oligodendrocytes.

They demonstrated how the same chemicals damage oligodendrocytes in the developing brains of mice. The researchers also linked exposure to one of the chemicals to poor neurological outcomes in children nationally.

"We found that oligodendrocytes -- but not other brain cells -- are surprisingly vulnerable to quaternary ammonium compounds and organophosphate flame retardants," said Erin Cohn, lead author and graduate student in the School of Medicine's Medical Scientist Training Program. "Understanding human exposure to these chemicals may help explain a missing link in how some neurological diseases arise."

The association between human exposure to these chemicals and effects on brain health requires further investigation, the experts warned. Future research must track the chemical levels in the brains of adults and children to determine the amount and length of exposure needed to cause or worsen disease.

"Our findings suggest that more comprehensive scrutiny of the impacts of these common household chemicals on brain health is necessary," Tesar said. "We hope our work will contribute to informed decisions regarding regulatory measures or behavioral interventions to minimize chemical exposure and protect human health."

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Green doesn't always mean clean: Cleaning products urgently need better regulation, researchers warn

Many cleaning products labelled as "green" emit just as many harmful chemicals as regular products, new research has revealed.

Researchers say there needs to be better regulation and more guidance for consumers about how safe cleaning products really are.

Potentially harmful

The study, published by The Royal Society of Chemistry in the journal Environmental Science: Processes & Impact, found that fragranced cleaning products can be potentially harmful for the air quality in people's homes.

Cleaning products emit a wide range of volatile organic compounds (VOCs), including some which are hazardous or can undergo chemical transformations to generate harmful secondary pollutants.

In recent years, "green" cleaners have become increasingly popular, with an implicit assumption that these are better for our health and the environment.

But the University of York research found this was not the case.

Secondary pollutants

As part of the study, the VOC composition of 10 regular and 13 green cleaners was examined by researchers.

Green cleaners generally emitted more monoterpenes than regular cleaners, resulting in increases in harmful secondary pollutant concentrations following use, such as formaldehyde and peroxyacyl nitrates.

The study found that the fragrance ingredients of these products were the source of the volatile monoterpenes.

As levels of these types of pollutants increase in the home, susceptible people can develop breathing problems or irritation of the eyes, nose, throat, or skin.

Repeated exposure to high concentrations of formaldehyde can possibly lead to cancer in some cases.

Misleading consumers

Ellen Harding-Smith, Environmental Chemistry researcher from the Department of Environment & Geography, said: "Our research found there is no strong evidence to suggest that clean green products are better for indoor air quality compared to regular products.

"In fact, there was very little difference. Many consumers are being misled by the marketing of these products and could be damaging the air quality in their homes as a result -- potentially putting their health at risk. For so many products on the supermarket shelves, green doesn't mean clean."

Compositional differences

The research was funded by the EPSRC and the project is called IMPeCCABLE.

It is a collaboration between the University of York's Department of Environment and Geography, the Department of Chemistry, and the Wolfson Atmospheric Chemistry Laboratory.

Miss Harding-Smith, who is PhD Candidate, added: "The study highlights potential compositional differences in the formulations of regular and green cleaners, for which there is currently very little information on in the available literature.

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Greenhouse gas repurposed

Cutting-edge University of Auckland research converted waste carbon dioxide into a potential precursor for chemicals and carbon-free fuel.

Dr Ziyun Wang's researchers in the School of Chemical Sciences, in collaboration with researchers at Chinese institutions, have demonstrated a method for turning CO2 into formic acid, reported in the journal Nature.

In benchtop experiments, a catalyst made from waste lead-acid batteries enabled a transformation which hadn't been possible using previous catalysts.

Formic acid -- the same substance produced by ants (formica is the Latin word for ant) -- is a colourless and pungent liquid with potential as a transportation fuel, for storing electrical energy and for enabling the petrochemical industry to cut CO2 emissions.

As emissions of carbon dioxide, the primary greenhouse gas, rise each year, scientists are looking into options for the capture and storage of CO2, for repurposing CO2, and for pursuing a carbon-free economy.

Wang's group is one of the world leaders in research into CO2 electrochemical reduction (CO2RR) using acidic rather than alkaline conditions.

"This innovation opens up exciting possibilities for carbon-neutral technologies," he says.

"In the future, cars and gas stations could be using repurposed carbon dioxide."

In tests, the new method efficiently converted CO2. for more than 5,000 hours, and the researchers' calculations suggest it can be cost-effectively scaled up for industry.

The experiments used a proton exchange membrane electrolyser.

Carbon dioxide flowed into an electrochemical cell and was converted into formic acid, just like charging a battery.

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Bit by bit, microplastics from tires are polluting our waterways

Urban stormwater particles from tyre wear were the most prevalent microplastic a new Griffith-led study has found.

Published in Environmental Science & Technology, the study showed that in stormwater runoff during rain approximately 19 out of every 20 microplastics collected were tyre wear particles with anywhere from 2 to 59 particles per litre of water.

"Pollution of our waterways by microplastics is an emerging environmental concern due to their persistence and accumulation in aquatic organisms and ecosystems," said lead author Dr Shima Ziajahromi, a research fellow at the Australian Rivers Institute.

"Stormwater runoff which contains a mixture of sediment, chemical, organic and physical pollutants, is a critical pathway for microplastics to washed off from urban environments during rain and into local aquatic habitats.

"But to date, our knowledge of the amount of microplastics in urban stormwater, particularly tyre wear particles, is limited, as is the potential strategies we can use to minimise this source."

Tyre rubber contains up to 2500 chemicals with the contaminants that leach from tyres considered more toxic to bacteria and microalgae than other plastic polymers.

"Due to the analytical challenges in measuring this source of microplastics in stormwater, research to date often lacks information about the actual number of tyre wear particles water samples," said Dr Ziajahromi.

Quantitative information of this type is crucial to improve our understanding of the amount of tyre wear particles in stormwater, assess the risk to the environment, and to develop management strategies.

"Our study quantified and characterize microplastics and tyre wear particles in both stormwater runoff and sediment of stormwater drainage systems in Queensland," said co-author Professor Fred Leusch, who leads the Australian Rivers Institute's Toxicology Research Program.

"We also assessed the effectiveness of a stormwater treatment device to capture and remove these contaminants from stormwater and evaluated the role of a constructed stormwater wetland for capturing microplastics in the sediment, removing it from stormwater runoff.

"The device is a bag made of 0.2 millimetre mesh which can be retrofitted to stormwater drains. Although originally designed to capture gross pollutants, sediment, litter and oil and grease, it significantly reduced microplastics from raw runoff, with up to 88% less microplastics in treated water which had passed through the device."

Sediment samples collected from the inlet and outlet of a constructed stormwater wetland contained between 1450 to 4740 particles in every kilogram of sediment, with more microplastics in the sediment at the inlet than the outlet, indicating the wetland's ability to remove them from stormwater.

"Microplastics that enter constructed wetlands for stormwater drainage systems settle in the sediment and form a biofilm, leading to their accumulation over time, removing them from stormwater runoff," said Dr Ziajahromi.

"Urban stormwater runoff typically requires treatment for the removal of suspended solids and nutrients such as nitrogen and phosphorus in many jurisdictions in Australia, with some also requiring the removal of gross pollutants. However, regulations are lagging behind when it comes to microplastics and tyre wear particles."

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Widespread illegal trade of hazardous chemicals

54 chemicals and groups of chemicals are covered by the Rotterdam Convention due to their high potential to cause severe harm on human health and the environment. These include mercury compounds, various pesticides and five of the six types of asbestos. The Convention, also known as the PIC Convention (Prior Informed Consent), does not ban these hazardous substances. However, the parties may only trade them among themselves if the importing country has expressly consented to the import.

The PIC procedure is primarily intended to protect developing countries from the uncontrolled import of highly hazardous chemicals, since these countries often lack the necessary infrastructure to safely process and dispose of them. Now, a new study initiated by Empa scientists delivers sobering results: The PIC procedure is defaulted on in nearly half of the traded volume of these chemicals.

Worldwide violations

For the study, published on 10 July in the journal Nature Sustainability, researchers from China and Switzerland analyzed public trade data from the United Nations Comtrade database for 46 of the 54 listed chemicals. A total of 64.5 million tons were traded globally from 2004 to 2019. Of these, 27.5 million tons were traded illegally, i.e., exported to countries that had explicitly refused to import them.

Non-compliance with the Rotterdam Convention is a worldwide phenomenon, especially by many countries in Western, Central and Southern Europe, as well as South and Southeast Asia. At the same time, these regions were also the most affected by illegal imports, along with the Middle East and North Africa, as well as Latin America. "This prevalent illegal trade is highly concerning because it undermines global efforts to protect us and our environment from hazardous chemicals," says Empa researcher Zhanyun Wang, who initiated the study.

According to Wang and his co-authors, the result of the study is a rather conservative estimate of the illicit trade in hazardous chemicals, as situations such as smuggling and black markets were not includes in the analysis. In addition, the US, for example, exported about four million tons of chemicals to countries that refuse to import them under the Convention. However, this is not necessarily illegal -- because the US has not ratified the Rotterdam Convention and is subject to different rules.

Ongoing large-scale trade

Wang also considers the very high overall volume of hazardous substances being traded as problematic. Of the total 64.5 million tons, the majority -- 55.3 million tons -- is ethylene dichloride, a carcinogenic and organ-damaging solvent used in the production of polyvinyl chloride (PVC). In second place, with 6.3 million tons, is the toxic reagent, disinfectant and pesticide ethylene dioxide.

The other chemicals, which are predominantly pesticides, make up a relatively small portion of the total. "But we see that these highly toxic compounds are still being traded in significant quantities," Wang says. "Since the Rotterdam Convention came into force, trade has decreased only slightly. Yet for many of these substances, we've known for decades how harmful they are."

Surprisingly, the authors also discovered a brisk trade in some substances that have been severely restricted or even banned for years to decades. These include, for instance, the legacy toxic pesticides aldrin, chlordane, heptachlor and dieldrin, which have been banned worldwide as the "Dirty Dozen" under the Stockholm Convention since 2004. Also still traded, albeit in much smaller quantities of several thousand tons, are the notoriously neurotoxic compounds tetraethyl lead and tetramethyl lead. Despite decades of global efforts to phase them out in gasoline for normal cars, they seem to be still used in certain specialty fuels.

Strengthening national and international action

All of the data used in the study are public -- so why aren't the countries addressing the defaults? There are several reasons. "For many countries, the environmental ministry is responsible for implementing the Rotterdam Convention," Wang explains. "But trade is supervised by the customs authority." In addition, there are often insufficient resources available to monitor chemical trade, especially in developing countries.

The researchers recommend that international and national action needs to step up to address global trade of highly hazardous chemicals, particularly illegal trade. Among others, other problematic chemicals should be listed under the Convention, such as chrysotile asbestos. This type of asbestos is by far the most common -- and the only one of the six types of asbestos not yet covered by the Convention. "Switzerland has recently taken the initiative here to bring about changes, along with several other countries, but so far without success," Wang says.

The Rotterdam Convention, meanwhile, has only had a Compliance Committee to monitor and address its implementation since 2020. "We are hopeful that this, together with national efforts on reducing the production and use of highly hazardous chemicals, will greatly reduce illegal trade in the future," Wang says.

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Groundbreaking images of root chemicals offer new insights on plant growth

On a sunny springtime stroll through a park, it's easy to ignore the parts of plants that are hidden from view. Plant biologists see things differently. They look below the surface where plant roots are organized in elaborate systems that are critical to the organism's development. Intricately organized tree root systems, for example, can span as far underground as the tree grows high above the soil.

Applying an advanced imaging technology to plant roots, researchers at the University of California San Diego and Stanford University have developed a new understanding of essential root chemicals that are responsible for plant growth. Using a type of mass spectrometer, a study led by UC San Diego Biological Sciences Postdoctoral Scholar Tao Zhang and Assistant Professor Alexandra Dickinson produced a "roadmap" that profiles where key small molecules are distributed along stem cells of maize (corn) plant roots and how their placement factors into the plant's maturation. The findings were published in the journal Nature Communications.

"This chemical roadmap provides a resource that scientists can use to find new ways of regulating plant growth," said Dickinson, a faculty member in the Department of Cell and Developmental Biology. "Having more information about how roots grow could be useful in conservation as we think about protecting our plants in natural environments and making them more sustainable, especially in agriculture."

While working as a visiting scientist at Stanford University, Dickinson began collaborating with study co-first author Sarah Noll and Professor Richard Zare, who developed a mass spectrometry imaging system that helps surgeons distinguish between cancerous and benign tissue during tumor-removal operations.

Dickinson, Zare and Noll adapted the technology -- called "desorption electrospray ionization mass spectrometry imaging" or DESI-MSI -- to probe plant roots for the chemicals involved in growth and energy production. They initially focused on maize plants at the root tips, where stem cells play an active role in the plant's development. Their method involved cutting through the center of the root to get a clear image of the chemicals inside.

"To help understand plant roots from the biology side, we needed to find out which chemicals are there," said Zare. "Our imaging system sprays out droplets that strike different portions of the root and dissolve chemicals at that location. A mass spectrometer collects the droplet splash and tells us what those dissolved chemicals are. By systematically scanning the droplet target spot we make a spatial map of the root chemicals."

The resulting images, believed to be some of the first to reveal the transition between stem cells and mature root tissue, show the foundational role of metabolites -- molecules involved in the plant's energy production. Tricarboxylic acid (TCA) cycle metabolites became the focus of the research since they were found to be a key player in controlling root development.

Coming into the study, the researchers expected a relatively uniform distribution of chemicals. Instead, with their chemical roadmap in hand, they found that TCA metabolites are clustered in patches across the root.

"I was surprised by how many chemicals are featured in really distinct patterns," said Dickinson. "We can see that the plant is doing this on purpose -- it needs these molecules in specific regions to grow properly." The Dickinson lab showed that these TCA metabolites have predictable effects in development, not only in maize, but in another plant species as well (Arabidopsis). This is likely because TCA metabolites are highly conserved -- they are made in all plants as well as animals.

Also emerging from the new images were previously unidentified chemical compounds. Dickinson says the mystery compounds could be critical for plant growth since they also are grouped in patterns at specific locations, suggesting a prominent role in development. Dickinson and her colleagues are now investigating these compounds and comparing varieties of maize that have different levels of stress resistance for adverse threats such as severe climate conditions and drought. The new information will help them develop novel chemical and genetic strategies for improving plant growth and stress resilience.

"We're looking at different maize plants that have drought resistance to see if we've already found chemicals that are specific to that variety that we haven't seen in other varieties," said Dickinson. "We think that could be a way to find new compounds that can promote growth, especially in harsh conditions."

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Tiny microbes could brew big benefits for green biomanufacturing

A research team led by Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley has engineered bacteria to produce new-to-nature carbon products that could provide a powerful route to sustainable biochemicals.

The advance -- which was recently announced in the journal Nature -- uses bacteria to combine natural enzymatic reactions with a new-to-nature reaction called the "carbene transfer reaction." This work could also one day help reduce industrial emissions because it offers sustainable alternatives to chemical manufacturing processes that typically rely on fossil fuels.

"What we showed in this paper is that we can synthesize everything in this reaction -- from natural enzymes to carbenes -- inside the bacterial cell. All you need to add is sugar and the cells do the rest," said Jay Keasling, a principal investigator of the study and CEO of the Department of Energy's Joint BioEnergy Institute (JBEI).

Carbenes are highly reactive carbon-based chemicals that can be used in many different types of reactions. For decades, scientists have wanted to use carbene reactions in the manufacturing of fuels and chemicals, and in drug discovery and synthesis.

But these carbene processes could only be carried out in small batches via test tubes and required expensive chemical substances to drive the reaction.

In the new study, the researchers replaced expensive chemical reactants with natural products that can be produced by an engineered strain of the bacteria Streptomyces. Because the bacteria use sugar to produce chemical products through cellular metabolism, "this work enables us to perform the carbene chemistry without toxic solvents or toxic gases typically used in chemical synthesis," said first author Jing Huang, a Berkeley Lab postdoctoral researcher in the Keasling Lab. "This biological process is much more environmentally friendly than the way chemicals are synthesized today," Huang said.

During experiments at JBEI, the researchers observed the engineered bacterium as it metabolized and converted sugars into the carbene precursor and the alkene substrate. The bacterium also expressed an evolved P450 enzyme that used those chemicals to produce cyclopropanes, high-energy molecules that could potentially be used in the sustainable production of novel bioactive compounds and advanced biofuels. "We can now perform these interesting reactions inside the bacterial cell. The cells produce all of the reagents and the cofactors, which means that you can scale this reaction to very large scales" for mass manufacturing, Keasling said.

Recruiting bacteria to synthesize chemicals could also play an integral role in reducing carbon emissions, Huang said. According to other Berkeley Lab researchers, close to 50% of greenhouse gas emissions come from the production of chemicals, iron and steel, and cement. Limiting global warming to 1.5 degrees Celsius above pre-industrial levels will require severely cutting greenhouse gas emissions in half by 2030, says a recent report by the Intergovernmental Panel on Climate Change.

Huang said that while this fully integrated system can be envisioned for a large number of carbene donor molecules and alkene substrates, it is not yet ready for commercialization.

"For every new advance, someone needs to take the first step. And in science, it can take years before you succeed. But you have to keep trying -- we can't afford to give up. I hope our work will inspire others to continue searching for greener, sustainable biomanufacturing solutions," Huang said.

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How a record-breaking copper catalyst converts CO2 into liquid fuels

Since the 1970s, scientists have known that copper has a special ability to transform carbon dioxide into valuable chemicals and fuels. But for many years, scientists have struggled to understand how this common metal works as an electrocatalyst, a mechanism that uses energy from electrons to chemically transform molecules into different products.

Now, a research team led by Lawrence Berkeley National Laboratory (Berkeley Lab) has gained new insight by capturing real-time movies of copper nanoparticles (copper particles engineered at the scale of a billionth of a meter) as they convert CO2 and water into renewable fuels and chemicals: ethylene, ethanol, and propanol, among others. The work was reported in the journal Nature last week.

"This is very exciting. After decades of work, we're finally able to show -- with undeniable proof -- how copper electrocatalysts excel in CO2 reduction," said Peidong Yang, a senior faculty scientist in Berkeley Lab's Materials Sciences and Chemical Sciences Divisions who led the study. Yang is also a professor of chemistry and materials science and engineering at UC Berkeley. "Knowing how copper is such an excellent electrocatalyst brings us steps closer to turning CO2 into new, renewable solar fuels through artificial photosynthesis."

The work was made possible by combining a new imaging technique called operando 4D electrochemical liquid-cell STEM (scanning transmission electron microscopy) with a soft X-ray probe to investigate the same sample environment: copper nanoparticles in liquid. First author Yao Yang, a UC Berkeley Miller postdoctoral fellow, conceived the groundbreaking approach under the guidance of Peidong Yang while working toward his Ph.D. in chemistry at Cornell University.

Scientists who study artificial photosynthesis materials and reactions have wanted to combine the power of an electron probe with X-rays, but the two techniques typically can't be performed by the same instrument.

Electron microscopes (such as STEM or TEM) use beams of electrons and excel at characterizing the atomic structure in parts of a material. In recent years, 4D STEM (or "2D raster of 2D diffraction patterns using scanning transmission electron microscopy") instruments, such as those at Berkeley Lab's Molecular Foundry, have pushed the boundaries of electron microscopy even further, enabling scientists to map out atomic or molecular regions in a variety of materials, from hard metallic glass to soft, flexible films.

On the other hand, soft (or lower-energy) X-rays are useful for identifying and tracking chemical reactions in real time in an operando, or real-world, environment.

But now, scientists can have the best of both worlds. At the heart of the new technique is an electrochemical "liquid cell" sample holder with remarkable versatility. A thousand times thinner than a human hair, the device is compatible with both STEM and X-ray instruments.

The electrochemical liquid cell's ultrathin design allows reliable imaging of delicate samples while protecting them from electron beam damage. A special electrode custom-designed by co-author Cheng Wang, a staff scientist at Berkeley Lab's Advanced Light Source, enabled the team to conduct X-ray experiments with the electrochemical liquid cell. Combining the two allows researchers to comprehensively characterize electrochemical reactions in real time and at the nanoscale.

Getting granular

During 4D-STEM experiments, Yao Yang and team used the new electrochemical liquid cell to observe copper nanoparticles (ranging in size from 7 nanometers to 18 nanometers) evolve into active nanograins during CO2 electrolysis -- a process that uses electricity to drive a reaction on the surface of an electrocatalyst.

The experiments revealed a surprise: copper nanoparticles combined into larger metallic copper "nanograins" within seconds of the electrochemical reaction.

To learn more, the team turned to Wang, who pioneered a technique known as "resonant soft X-ray scattering (RSoXS) for soft materials," at the Advanced Light Source more than 10 years ago.

With help from Wang, the research team used the same electrochemical liquid cell, but this time during RSoXS experiments, to determine whether copper nanograins facilitate CO2 reduction. Soft X-rays are ideal for studying how copper electrocatalysts evolve during CO2 reduction, Wang explained. By using RSoXS, researchers can monitor multiple reactions between thousands of nanoparticles in real time, and accurately identify chemical reactants and products.

The RSoXS experiments at the Advanced Light Source -- along with additional evidence gathered at Cornell High Energy Synchrotron Source (CHESS) -- proved that metallic copper nanograins serve as active sites for CO2 reduction. (Metallic copper, also known as copper(0), is a form of the element copper.)

During CO2 electrolysis, the copper nanoparticles change their structure during a process called "electrochemical scrambling." The copper nanoparticles' surface layer of oxide degrades, creating open sites on the copper surface for CO2 molecules to attach, explained Peidong Yang. And as CO2 "docks" or binds to the copper nanograin surface, electrons are then transferred to CO2, causing a reaction that simultaneously produces ethylene, ethanol, and propanol along with other multicarbon products.

"The copper nanograins essentially turn into little chemical manufacturing factories," Yao Yang said.

Further experiments at the Molecular Foundry, the Advanced Light Source, and CHESS revealed that size matters. All of the 7-nanometer copper nanoparticles participated in CO2 reduction, whereas the larger nanoparticles did not. In addition, the team learned that only metallic copper can efficiently reduce CO2 into multicarbon products. The findings have implications for "rationally designing efficient CO2 electrocatalysts," Peidong Yang said.

The new study also validated Peidong Yang's findings from 2017: That the 7-nanometer-sized copper nanoparticles require low inputs of energy to start CO2 reduction. As an electrocatalyst, the 7-nanometer copper nanoparticles required a record-low driving force that is about 300 millivolts less than typical bulk copper electrocatalysts. The best-performing catalysts that produce multicarbon products from CO2 typically operate at high driving force of 1 volt.

The copper nanograins could potentially boost the energy efficiency and productivity of some catalysts designed for artificial photosynthesis, a field of research that aims to produce solar fuels from sunlight, water, and CO2. Currently, researchers within the Department of Energy-funded Liquid Sunlight Alliance (LiSA) plan to use the copper nanograin catalysts in the design of future solar fuel devices.

"The technique's ability to record real-time movies of a chemical process opens up exciting opportunities to study many other electrochemical energy conversion processes. It's a huge breakthrough, and it would not have been possible without Yao and his pioneering work," Peidong Yang said.

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Mimicking an enigmatic property of circadian rhythms through an artificial chemical clock

Circadian rhythms are natural, internal oscillations that synchronize an organism's behaviors and physiological processes with their environment. These rhythms normally have a period of 24 hours and are regulated by internal chemical clocks that respond to cues from outside the body, such as light.

Although well studied in animals, plants, and bacteria, circadian rhythms all share an enigmatic property -- the oscillation period is not significantly affected by temperature, even though the rate of most biochemical reactions changes exponentially with temperature. This clearly indicates that some sort of temperature-compensation mechanism is at play. Interestingly, some scientists have managed to replicate such temperature-invariant qualities in certain oscillating chemical reactions. However, these reactions are often troublesome and require extremely precise adjustments on the reacting chemicals.

But what if there was a simpler way to achieve temperature compensation in an oscillating chemical reaction? In a recent study published in Scientific Reports, a team of researchers including Assistant Professor Yuhei Yamada of Tokyo Institute of Technology (Tokyo Tech), Japan, came up with a clever idea for a temperature compensation mechanism using a reaction called the Belousov-Zhabotinsky (BZ) oscillating reaction.

The key to their approach lies in soft, temperature-responsive gels made from poly(N-isopropylacrylamide), or 'PNIPAAm' for short, in which the BZ reaction can occur. These gels consist of polymeric strands that can accommodate a certain volume of solvent. However, because these gels shrink as temperature increases, the amount of solvent contained in the gel decreases as temperature rises.

The researchers exploited this property of PNIPAAm gels by adding ruthenium (Ru) sites on its constituent polymers. The periodic nature of the particular BZ reaction the researchers studied relies partially on the back-and-forth oxidation and reduction of ruthenium (Ru) ions. Thus, the speed of this reaction is affected by the relative concentrations of solvent and Ru. Because the PNIPAAm gels can accommodate less solvent when they shrink, the relative concentration of Ru in the gels increases with temperature.

As the research team demonstrated through experimental measurements and a thorough mathematical analysis, the abovementioned effects combine to form a temperature-compensation mechanism that renders the period of the BZ reaction unaffected by shifts in temperature. "The prepared BZ gels exhibited temperature compensability just like the circadian rhythms observed in living organisms," remarks Yamada.

Overall, this study demonstrates a completely new way to achieve temperature compensation in artificial biological clocks based on periodic reactions. Intriguingly, it's even possible that similar temperature-compensation mechanisms using temperature-responsive soft bodies exist in biological systems in nature, as Yamada explains: "Our study suggests that temperature compensation can be naturally self-sustainable through the output system of circadian machinery. This may explain why temperature compensation is a universal property of circadian rhythms seen in animals, plants, and bacteria, regardless of the molecular species involved."

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Team recycles previously unrecyclable plastic

PVC, or polyvinyl chloride, is one of the most produced plastics in the United States and the third highest by volume in the world.

PVC makes up a vast amount of plastics we use on a daily basis. Much of the plastic used in hospital equipment -- tubing, blood bags, masks and more -- is PVC, as is most of the piping used in modern plumbing. Window frames, housing trim, siding and flooring are made of, or include, PVC. It coats electrical wiring and comprises materials such as shower curtains, tents, tarps and clothing.

It also has a zero percent recycling rate in the United States.

Now, University of Michigan researchers, led by study first author Danielle Fagnani and principal investigator Anne McNeil, have discovered a way to chemically recycle PVC into usable material. The most fortuitous part of the study? The researchers found a way to use the phthalates in the plasticizers -- one of PVC's most noxious components -- as the mediator for the chemical reaction. Their results are published in the journal Nature Chemistry.

"PVC is the kind of plastic that no one wants to deal with because it has its own unique set of problems," said Fagnani, who completed the work as a postdoctoral researcher in the U-M Department of Chemistry. "PVC usually contains a lot of plasticizers, which contaminate everything in the recycling stream and are usually very toxic. It also releases hydrochloric acid really rapidly with some heat."

Plastic is typically recycled by melting it down and reforming it into the lower quality materials in a process called mechanical recycling. But when heat is applied to PVC, one of its primary components, called plasticizers, leach out of the material very easily, McNeil says.

They then can slip into other plastics in the recycling stream. Additionally, hydrochloric acid releases easily out of PVC with heat. It could corrode the recycling equipment and cause chemical burns to skin and eyes -- not ideal for workers in a recycling plant.

What's more, phthalates -- a common plasticizer -- are highly toxic endocrine disruptors, which means they can interfere with the thyroid hormone, growth hormones and hormones involved with reproduction in mammals, including humans.

So, to find a way to recycle PVC that does not require heat, Fagnani began exploring electrochemistry. Along the way, she and the team discovered that the plasticizer that presents one of the major recycling difficulties could be used in the method to break down PVC. In fact, the plasticizer improves the efficiency of the method, and the electrochemical method resolves the issue with hydrochloric acid.

"What we found is that it still releases hydrochloric acid, but at a much slower, more controlled rate," Fagnani said.

PVC is a polymer with a hydrocarbon backbone, Fagnani says, composed of single carbon-carbon bonds. Attached to every other carbon group is a chlorine group. Under heat activation, hydrochloric acid rapidly pops off, resulting in a carbon-carbon double bond along the polymer's backbone.

But the research team instead uses electrochemistry to introduce an electron into the system, which causes the system to have a negative charge. This breaks the carbon-chloride bond and results in a negatively charged chloride ion. Because the researchers are using electrochemistry, they can meter the rate at which electrons are introduced into the system -- which controls how quickly hydrochloric acid is produced.

The acid can then be used by industries as a reagent for other chemical reactions. The chloride ions can also be used to chlorinate small molecules called arenes. These arenes can be used in pharmaceutical and agricultural components. There is material left from the polymer, for which McNeil says the group is still looking for a use. Fagnani says the study shows how scientists might think about chemically recycling other difficult materials.

"Let's be strategic with the additives that are in plastics formulations. Let's think about the during-use and end-of-use from the perspective of the additives," said Fagnani, who is now a research scientist at Ashland, a company focused on making biodegradable specialty additives to consumer goods such as laundry detergents, sunscreens and shampoos. "Current group members are trying to improve the efficiency of this process even more."

The focus of McNeil's lab has been to develop ways to chemically recycle different kinds of plastics. Breaking plastics into their constituent parts could produce non-degraded materials that industry can incorporate back into production.

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New technology creates carbon neutral chemicals out of thin air

It is possible to capture carbon dioxide (CO2) from the surrounding atmosphere and repurpose it into useful chemicals usually made from fossil fuels, according to a study from the University of Surrey.

The technology could allow scientists to both capture CO2 and transform it into useful chemicals such as carbon monoxide and synthetic natural gas in one circular process.

Dr Melis Duyar, Senior Lecturer of Chemical Engineering at the University of Surrey commented:

"Capturing CO2 from the surrounding air and directly converting it into useful products is exactly what we need to approach carbon neutrality in the chemicals sector. This could very well be a milestone in the steps needed for the UK to reach its 2050 net-zero goals.

"We need to get away from our current thinking on how we produce chemicals, as current practices rely on fossil fuels which are not sustainable. With this technology we can supply chemicals with a much lower carbon footprint and look at replacing fossil fuels with carbon dioxide and renewable hydrogen as the building blocks of other important chemicals."

The technology uses patent-pending switchable Dual Function Materials (DFMs), that capture carbon dioxide on their surface and catalyse the conversion of captured CO2 directly into chemicals. The "switchable" nature of the DFMs comes from their ability to produce multiple chemicals depending on the operating conditions or the composition of the added reactant. This makes the technology responsive to variations in demand for chemicals as well as availability of renewable hydrogen as a reactant.

Dr Duyar continued:

"These outcomes are a testament to the research excellence at Surrey, with continuously improving facilities, internal funding schemes and a collaborative culture."

Loukia-Pantzechroula Merkouri, Postgraduate student leading this research at the University of Surrey added:

"Not only does this research demonstrate a viable solution to the production of carbon neutral fuels and chemicals, but it also offers an innovative approach to combat the ever-increasing CO2 emissions contributing to global warming."

Read more at Science Daily

Laughing gas in space could mean life

Scientists at UC Riverside are suggesting something is missing from the typical roster of chemicals that astrobiologists use to search for life on planets around other stars -- laughing gas.

Chemical compounds in a planet's atmosphere that could indicate life, called biosignatures, typically include gases found in abundance in Earth's atmosphere today.

"There's been a lot of thought put into oxygen and methane as biosignatures. Fewer researchers have seriously considered nitrous oxide, but we think that may be a mistake," said Eddie Schwieterman, an astrobiologist in UCR's Department of Earth and Planetary Sciences.

This conclusion, and the modeling work that led to it, are detailed in an article published today in the Astrophysical Journal.

To reach it, Schwieterman led a team of researchers that determined how much nitrous oxide living things on a planet similar to Earth could possibly produce. They then made models simulating that planet around different kinds of stars and determined amounts of N2O that could be detected by an observatory like the James Webb Space Telescope.

"In a star system like TRAPPIST-1, the nearest and best system to observe the atmospheres of rocky planets, you could potentially detect nitrous oxide at levels comparable to CO2 or methane," Schwieterman said.

There are multiple ways that living things can create nitrous oxide, or N2O. Microorganisms are constantly transforming other nitrogen compounds into N2O, a metabolic process that can yield useful cellular energy.

"Life generates nitrogen waste products that are converted by some microorganisms into nitrates. In a fish tank, these nitrates build up, which is why you have to change the water," Schwieterman said

"However, under the right conditions in the ocean, certain bacteria can convert those nitrates into N2O," Schwieterman said. "The gas then leaks into the atmosphere."

Under certain circumstances, N2O could be detected in an atmosphere and still not indicate life. Schwieterman's team accounted for this in their modeling. A small amount of nitrous oxide is created by lightning, for example. But alongside N2O, lightning also creates nitrogen dioxide, which would offer astrobiologists a clue that non-living weather or geological processes created the gas.

Others who have considered N2O as a biosignature gas often conclude it would be difficult to detect from so far away. Schwieterman explained that this conclusion is based on N2O concentrations in Earth's atmosphere today. Because there isn't a lot of it on this planet, which is teeming with life, some believe it would also be hard to detect elsewhere.

"This conclusion doesn't account for periods in Earth's history where ocean conditions would have allowed for much greater biological release of N2O. Conditions in those periods might mirror where an exoplanet is today," Schwieterman said.

Schwieterman added that common stars like K and M dwarfs produce a light spectrum that is less effective at breaking up the N2O molecule than our sun is. These two effects combined could greatly increase the predicted amount of this biosignature gas on an inhabited world.

The research team included UCR astrobiologists Daria Pidhorodetska, Andy Ridgwell, and Timothy Lyons, as well as scientists from Purdue University, the Georgia Institute of Technology, American University, and the NASA Goddard Space Flight Center.

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On-site reactors could affordably turn CO2 into valuable chemicals

New technology developed at the University of Waterloo could make a significant difference in the fight against climate change by affordably converting harmful carbon dioxide (CO2) into fuels and other valuable chemicals on an industrial scale.

Outlined in a study published today in the journal Nature Energy, the system yields 10 times more carbon monoxide (CO) -- which can be used to make ethanol, methane and other desirable substances -- than existing, small-scale technologies now limited to testing in laboratories.

Its individual cells can also be stacked to form reactors of any size, making the technology a customizable, economically viable solution that could be installed right on site, for example, at factories with CO2 emissions.

"This is a critical bridge to connect CO2 lab technology to industrial applications," said Dr. Zhongwei Chen, a chemical engineering professor at Waterloo. "Without it, it is very difficult for materials-based technologies to be used commercially because they are just too expensive."

The system features devices known as electrolyzers that convert CO2, a major greenhouse gas produced by burning fossil fuels, into CO using water and electricity.

Electrolyzers developed by the researchers have new electrodes and a new kind of liquid-based electrolyte, which is saturated with CO2 and flowed through the devices for conversion into CO via an electrochemical reaction.

Their electrolyzers are essentially 10-centimetre by 10-centimetre cells, many times larger than existing devices, that can be stacked and configured in reactors of any size.

"This is a completely new model for a CO2 reactor," said Chen, the Canada Research Chair in Advanced Materials for Clean Energy. "It makes the whole process economically viable for industrialization and can be customized to meet specific requirements."

The researchers envision on-site reactors at coal-fired power plants and factories, perhaps the size of a house or more, that would be directly fed CO2 emissions, further reducing costs by eliminating the need to capture and collect CO2 first.

They are also developing plans to power the reactors with on-site renewable energy sources such as solar panels, contributing to the environmental benefits.

"I'm excited by the potential of this technology," Chen said. "If we really want to make a difference by reducing emissions, we have to concentrate on reducing costs to make it affordable."

Read more at Science Daily

How fish survive the extreme pressures of life in the oceans

Scientists have discovered how a chemical in the cells of marine organisms enables them to survive the high pressures found in the deep oceans.

The deeper sea creatures live, the more inhospitable and extreme the environment they must cope with. In one of the deepest points in the Pacific -- the Mariana Trench, 11 kilometers below the sea surface -- the pressure is 1.1 kbar or eight tons per square inch. That is a 1,100-fold increase of the pressure experienced at the Earth's surface.

Under normal or atmospheric pressure, water molecules form a tetrahedron-like network.

Network of water molecules changes shape

At high pressure, though, the network of water molecules begins to distort and change shape. When this happens to the water inside living cells, it prevents vital bio-chemical processes from taking place -- and kills the organism.

In reporting their findings, the researchers in Leeds have for the first time been able to provide an explanation of how a molecule found in the cells of marine organisms counteracts the effect of external pressure on the water molecules.

Professor Lorna Dougan, from the School of Physics and Astronomy at Leeds, said: "Life has adapted to survive and thrive in environmental extremes. In the depths of the oceans, organisms live under extreme high pressures that would destroy human life.

"These high pressures distort the liquid water that resides in all life, resulting in detrimental impacts to the biomolecules that underpin all biological processes.

"We need to understand what happens to water under pressure and how pressure-adapted organisms combat these effects. If we can understand how these organisms survive at extreme pressure, we can apply these findings to the wider study of biomolecular stability."

Trimethylamine N-oxide or TMAO

The molecule found in cells that produces the protective effect against high external pressure is called TMAO -- trimethylamine N-oxide. Studies have shown that the amount of TMAO in ocean-dwelling organisms increases in line with the depth of their habitat.

Led by Dr Harrison Laurent, also from the School of Physics and Astronomy, the study used one of the most advanced analytical facilities in the world to investigate how intense pressure alters the hydrogen bonds between neighbouring water molecules.

Neutron scattering

Called the ISIS Neutron and Muon Source, the analytical facility at the STFC Rutherford Appleton Laboratory in Oxfordshire was used to fire a beam of neutrons -- which are sub-atomic particles -- at samples of water with and without TMAO. The analysis was done at low pressure, 25 bar, and at high pressure, 4 kbar.

The test revealed details of the atomic structure of the water molecules.

At high pressure, the hydrogen bonds in the pure water sample became distorted and less stable and the overall network of water molecules became compacted.

The presence of TMAO, however, strengthened and stabilised the hydrogen bonding and maintained the network structure of the water molecules.

Dr Laurent said: "The TMAO provides a structural anchor which results in the water being able to resist the extreme pressure it is under. The findings are important because they help scientists understand the processes by which organisms have adapted to survive the extreme conditions found in the oceans."

From the study, the research team have also been able to develop what is called an "osmolyte protection ratio," which predicts the level of TMAO needed in the cells of marine organisms so they can survive at a specific depth in the oceans.

Professor Dougan added: "Professor Dougan added: "Our study provides a bridge between water under pressure at the molecular level and the wonderful ability of organisms which thrive under high pressure in depths of the oceans.

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Flowers' unseen colors can help ensure pollination, survival

You can't see it, but different substances in the petals of flowers create a "bulls-eye" for pollinating insects, according to a Clemson University scientist whose research sheds light on chemical changes in flowers which helps them respond to environmental changes, including climate change, that might threaten their survival.

Matthew H. Koski, an assistant professor of biological sciences in the Clemson College of Science, led a research team that studied the bright, yellow flowers of Argentina anserina -- a member of the rose family commonly known as silverweed -- to learn how pigments in the petals that are visible only in the ultraviolet spectrum play an integral part in the plant's plasticity; that is, its ability to quickly respond to a changing environment. The team also included Clemson researchers Lindsay M. Finnell, Elizabeth Leonard and Nishanth Tharayil.

The journal Evolution featured the findings on the cover of its March edition.

The researchers studied silverweed growing at different elevations in southwestern Colorado to better understand the roles of the various UV-absorbing chemicals in the plants' petals and how these chemicals work to aid in pollination and, thus, reproduction.

Koski explained that although humans cannot see the UV patterns on the flower's petals, many of its pollinators can.

"I've always been fascinated with how [color variation of flowers] arises and how it evolves and what factors drive the evolution of color variation," Koski said, "so I got interested in thinking about how we perceive color versus how the organisms that interact more frequently with flowers perceive color."

"Insects -- pollinators, for example -- see in the ultraviolet spectrum," he continued. "So, flowers that reflect or absorb ultraviolet wavelengths give (to pollinators) the perception of different colors that we can't see. I've been fascinated with uncovering what these UV signals might be doing functionally with respect to pollination. When I thought about the trait of interest in ultraviolet absorption, it is biochemistry. It's a biochemical trait that leads to different perceptions of UV absorption and reflectance."

Koski said a wide range of plants have concentrations of UV-absorbing chemicals at the base of the flower's petals, while the tips of the petals have more UV-reflecting chemicals. He said this creates an overall "bulls-eye" effect that guides insects in their search for pollen.

The team wanted to uncover more about how the plants adapt to thrive in different environments -- in this case, a difference in altitude of 1,000 meters. They found that flowers at different altitudes adapt to their environments by producing differing amounts of UV-blocking or UV-absorbing chemicals.

"At higher elevations, there are always more UV-absorbing compounds or larger spatial area of UV absorption on the petals, compared to the low-elevation populations," Koski said.

The researchers said this demonstrates the plant's plasticity, which Koski defined as how differing traits arise in the same organisms under different environmental conditions. This is a critical step in understanding how organisms adapt to survive change.

"What's important about plasticity is, when we think about climate change and global change, plasticity is one mechanism by which natural populations can respond really rapidly to changing climates and persist under those climates," he said. "The process of evolution, where you're getting changes in the genetic code over time, is thought to proceed more slowly than just responding plastically to environmental change."

Koski said that one question raised by the research is whether plastic responses to environmental situations are adaptive. Do they offer any advantage to an organism, or are they changes in how a trait develops because of the environment without impacting plant fitness?

"One thing this study found is that the plastic change in UV pigmentation benefited the plant, especially the ones at high elevations because increases in ultraviolet absorption on the petals resulted in increased pollen viability," he explained.

Koski went on to say the research will help scientists better understand how organisms respond to environmental changes and even predict if or how well some organisms would be able to survive rapid environmental change, such as from global climate change. The research could also be important for agriculture, he said, because some of the same UV-sensitive pigments at work in silverweed are also present in commercial crops such as mustard and sunflowers.

"It's interesting to think about if abiotic factors like UV or temperature are shifting the expression of these traits, how is that going to impact how pollinators view the flowers, and how's that going to affect things like yield and seed production in crops, for example," Koski said.

Read more at Science Daily

How some gut microbes awaken 'zombie' viruses in their neighbors

Some gut bacteria have a spooky superpower: they can reanimate dormant viruses lurking within other microbes.

This viral awakening unleashes full-blown infections that destroy the virus-carrying cells, Howard Hughes Medical Institute Investigator Emily Balskus's lab first published as a preprint on bioRxiv and later in the journal Nature on February 23, 2022. A cryptic molecule called colibactin can summon the killer viruses from their slumber, they found.

Microbes often generate noxious compounds to attack one another within the cramped quarters of the gut. But among these chemical weapons, colibactin appears unusual, says Balskus, a chemical biologist at Harvard University. "It doesn't directly kill the target organisms, which is what we normally think of bacterial toxins doing within microbial communities." Instead, colibactin tweaks microbial cells just so, activating latent -- and lethal -- viruses tucked away in some bacteria's genomes.

Humans have long sought out the potent compounds that microbes produce. "We know a lot about their chemical properties, we purify them in the lab, and we use them as medicine, including antibiotics," says Breck Duerkop, who studies bacterial viruses at the University of Colorado School of Medicine.

But why bacteria make these compounds and what effects they have on neighboring organisms are open-ended questions, says Duerkop, who was not involved in this research. He calls Balskus's teams new work "one step in the right direction."

Chemical dark matter

Scientists have known for years that colibactin can wreak havoc on human cells. Research by Balskus and many others has shown that the compound damages DNA, which can lead to colorectal cancer. But establishing a connection between this compound and disease proved particularly formidable.

In 2006, a French team reported that mammalian cells that encountered the gut bacteria E. coli suffered fatal damage to their DNA. The researchers linked this damage to a cluster of E. coli genes encoding machinery for building a complex molecule. Dubbed colibactin, the molecule was extraordinarily difficult to study. After many tries, researchers simply couldn't isolate it from the E. coli making it.

Colibactin is one of many ephemeral compounds that scientists suspect microbes make. Like invisible particles of dark matter in space, this "chemical dark matter" requires creative means to study. As part of her exploration of the gut's microbial chemistry, Balskus uses indirect approaches to examine these elusive molecules.

Over the past 10 years, her team has probed colibactin by studying the microbial machinery that manufactures it. She and her colleagues have pieced together colibactin's structure and determined that it damages DNA by forming errant connections within the double helix.

Building off this work, scientists elsewhere uncovered a definitive link to cancer: the molecule's distinctive fingerprints appear in genes known to drive colorectal tumor growth.

A role for viruses

Balskus's most recent colibactin study got its start with another disease: COVID-19. Like many other labs, hers had to rearrange things to reduce physical contact among researchers. As part of the reshuffling, postdoc Justin Silpe and graduate student Joel Wong ended up working near one another for the first time. Their conversations led them and Balskus to wonder how colibactin affected other microbes in a crowded gut.

Early on, they found that exposing colibactin-producing bacteria to non-producers had little effect, suggesting that, on its own, the molecule isn't particularly deadly. Silpe and Wong weren't sure if colibactin, a large, unstable molecule, could even enter bacterial cells to damage their DNA. They then wondered if a third party -- bacteria-infecting viruses -- might be involved. Hardly more than bits of genetic information, these viruses can slip into bacteria's DNA and lie quietly in wait. Then, once triggered, they cause an infection that blows up the cell like a landmine.

When the researchers grew colibactin producers alongside bacteria carrying such latent viruses, they saw the number of viral particles spike, and the growth of many virus-containing bacteria drop. That suggested the molecule sparked a surge in active, cell-killing infections. Colibactin does indeed enter bacteria and damage DNA, the team showed. That damage sounds a cellular wake-up bell that rouses the viruses.

Many microbes appeared equipped to protect themselves against colibactin. Balskus's lab identified a resistance gene encoding a protein that neutralizes the compound in a wide variety of bacteria.

Though colibactin clearly has a dangerous side, it may serve as more than just a lethal weapon, Balskus says. For example, both DNA damage and awakened viruses can also induce genetic changes, rather than death, in neighboring bacteria, potentially benefiting colibactin producers.

Balskus's team's discoveries suggest that cancer may be collateral damage caused by whatever else colibactin-producing bacteria are doing. "We always suspected that bacteria made this toxin to target other bacteria in some way," she says. "It didn't make sense from an evolutionary perspective that they acquired it to target human cells."

Read more at Science Daily

Chemical history of the Milky Way revealed by new catalog of tens of millions of stars

University of Notre Dame researchers, along with collaborators in China and Australia, published a new sample catalog of more than 24 million stars that can be used to decipher the chemical history of elements in the Milky Way Galaxy.

The research, published this month in The Astrophysical Journal, represents about one-hundredth of a percent of the roughly 240 billion stars in the Milky Way. It marks a milestone for Timothy Beers, the Grace-Rupley Professor of Physics at Notre Dame, who has spent most of his career planning and executing ever-larger surveys of stars to decipher the galaxy's formation and chemical evolution -- a field called galactic archaeology. Researchers employed a new approach to measure the light from each star to infer the abundances of heavy metals such as iron. They also measured their distances, motions and ages.

"The elemental abundances of individual stars trace the chemical enrichment of the Milky Way galaxy, from when it first began to form stars shortly after the Big Bang to the present," Beers said.

"Combining this information with the stellar distances and motions allows us to constrain the origin of different components in the galaxy, such as the halo and disk populations," he continued. "Adding age estimates puts a `clock' on the process, so that a much more complete picture of the entire process can be drawn."

Previous spectroscopic work by Beers and collaborators provided the information for the tens of thousands of stars that were used to calibrate the new approach, based on precision photometric measurements. The recent research used large photometric samples obtained with the Australian SkyMapper Southern Survey and the European Gaia satellite mission to calibrate estimates of metallicity.

Until recently, the only means to obtain accurate estimates of the content of heavy metals, such as iron, for large numbers of stars was by taking low- and medium-resolution spectra that could be analyzed to extract this information. The process was long and painstaking.

Beers is most interested in the stars with the lowest metallicities -- very metal-poor stars with iron abundances less than 1 percent that of the sun -- because they were born early in the history of the universe, and therefore reveal the origin of elements in the periodic table. In the early 1980s, when Beers started his work, researchers knew of only about 20 very metal-poor stars. This new catalog brings the total of what Beers refers to as "fossils of the night sky" to more than 500,000.

Containing more than 19 million dwarf and five million giant stars, the new catalog is expected to advance the knowledge of how the Milky Way was formed in a variety of ways, Beers said. These include characterizing the structure of the galactic thin/thick disks -- the structural components of spiral galaxies -- as well as the population of stars and globular clusters that surround most disk galaxies, called the stellar halo. The catalog of stars will also help researchers identify the trails of stars left behind from disrupted dwarf galaxies and globular clusters.

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

Possible chemical leftovers from early Earth sit near the core

Let's take a journey into the depths of the Earth, down through the crust and mantle nearly to the core. We'll use seismic waves to show the way, since they echo through the planet following an earthquake and reveal its internal structure like radar waves.

Down near the core, there are zones where seismic waves slow to a crawl. New research from the University of Utah finds that these enigmatic and descriptively-named ultra-low velocity zones are surprisingly layered. Modeling suggests that it's possible some of these zones are leftovers from the processes that shaped the early Earth -- remnants of incomplete mixing like clumps of flour in the bottom of a bowl of batter.

"Of all of the features we know about in the deep mantle, ultra-low velocity zones represent what are probably the most extreme," says Michael S. Thorne, associate professor in the Department of Geology and Geophysics. "Indeed, these are some of the most extreme features found anywhere in the planet."

The study is published in Nature Geoscience and is funded by the National Science Foundation.

Into the mantle

Let's review how the interior of the Earth is structured. We live on the crust, a thin layer of solid rock. Between the crust and the iron-nickel core at the center of the planet is the mantle. It's not an ocean of lava -- instead it's more like solid rock, but hot and with an ability to move that drives plate tectonics at the surface.

How can we have any idea what's going on in the mantle and the core? Seismic waves. As they ripple through the Earth after an earthquake, scientists on the surface can measure how and when the waves arrive at monitoring stations around the world. From those measurements, they can back-calculate how the waves were reflected and deflected by structures within the Earth, including layers of different densities. That's how we know where the boundaries are between the crust, mantle and core -- and partially how we know what they're made of.

Ultra-low velocity zones sit at the bottom of the mantle, atop the liquid metal outer core. In these areas, seismic waves slow by as much as half, and density goes up by a third.

Scientists initially thought that these zones were areas where the mantle was partially melted, and might be the source of magma for so-called "hot spot" volcanic regions like Iceland.

"But most of the things we call ultra-low velocity zones don't appear to be located beneath hot spot volcanoes," Thorne says, "so that cannot be the whole story."

So Thorne, postdoctoral scholar Surya Pachhai and colleagues from the Australian National University, Arizona State University and the University of Calgary set out to explore an alternate hypothesis: that the ultra-low velocity zones may be regions made of different rocks than the rest of the mantle -- and that their composition may hearken back to the early Earth.

Perhaps, Thorne says, ultra-low velocity zones could be collections of iron oxide, which we see as rust at the surface but which can behave as a metal in the deep mantle. If that's the case, pockets of iron oxide just outside the core might influence the Earth's magnetic field which is generated just below.

"The physical properties of ultra-low velocity zones are linked to their origin," Pachhai says, "which in turn provides important information about the thermal and chemical status, evolution and dynamics of Earth's lowermost mantle -- an essential part of mantle convection that drives plate tectonics."

Reverse-engineering seismic waves

To get a clear picture, the researchers studied ultra-low velocity zones beneath the Coral Sea, between Australia and New Zealand. It's an ideal location because of an abundance of earthquakes in the area, which provide a high-resolution seismic picture of the core-mantle boundary. The hope was that high-resolution observations could reveal more about how ultra-low velocity zones are put together.

But getting a seismic image of something through nearly 1800 miles of crust and mantle isn't easy. It's also not always conclusive -- a thick layer of low-velocity material might reflect seismic waves the same way as a thin layer of even lower-velocity material.

So the team used a reverse-engineering approach.

"We can create a model of the Earth that includes ultra-low wave speed reductions," Pachhai says, "and then run a computer simulation that tells us what the seismic waveforms would look like if that is what the Earth actually looked like. Our next step is to compare those predicted recordings with the recordings that we actually have."

Over hundreds of thousands of model runs, the method, called "Bayesian inversion," yields a mathematically robust model of the interior with a good understanding of the uncertainties and trade-offs of different assumptions in the model.

One particular question the researchers wanted to answer is whether there are internal structures, such as layers, within ultra-low velocity zones. The answer, according to the models, is that layers are highly likely. This is a big deal, because it shows the way to understanding how these zones came to be.

"To our knowledge this is the first study using such a Bayesian approach at this level of detail to investigate ultra-low velocity zones," Pachhai says, "and it is also the first study to demonstrate strong layering within an ultra-low velocity zone."

Looking back at the origins of the planet

What does it mean that there are likely layers?

More than four billion years ago, while dense iron was sinking to the core of the early Earth and lighter minerals were floating up into the mantle, a planetary object about the size of Mars may have slammed into the infant planet. The collision may have thrown debris into Earth's orbit that could have later formed the Moon. It also raised the temperature of the Earth significantly -- as you might expect from two planets smashing into each other.

"As a result, a large body of molten material, known as a magma ocean, formed," Pachhai says. The "ocean" would have consisted of rock, gases and crystals suspended in the magma.

The ocean would have sorted itself out as it cooled, with dense materials sinking and layering on to the bottom of the mantle.

Over the following billions of years, as the mantle churned and convected, the dense layer would have been pushed into small patches, showing up as the layered ultra-low velocity zones we see today.

"So the primary and most surprising finding is that the ultra-low velocity zones are not homogenous but contain strong heterogeneities (structural and compositional variations) within them," Pachhai says. "This finding changes our view on the origin and dynamics of ultra-low velocity zones . We found that this type of ultra-low velocity zone can be explained by chemical heterogeneities created at the very beginning of the Earth's history and that they are still not well mixed after 4.5 billion years of mantle convection."

Not the final word

The study provides some evidence of the origins of some ultra-low velocity zones, although there's also evidence to suggest different origins for others, such as melting of ocean crust that's sinking back into the mantle. But if at least some ultra-low velocity zones are leftovers from the early Earth, they preserve some of the history of the planet that otherwise has been lost.

Read more at Science Daily

Could acid-neutralizing life-forms make habitable pockets in Venus’ clouds?

It's hard to imagine a more inhospitable world than our closest planetary neighbor. With an atmosphere thick with carbon dioxide, and a surface hot enough to melt lead, Venus is a scorched and suffocating wasteland where life as we know it could not survive. The planet's clouds are similarly hostile, blanketing the planet in droplets of sulfuric acid caustic enough to burn a hole through human skin.

And yet, a new study supports the longstanding idea that if life exists, it might make a home in Venus' clouds. The study's authors, from MIT, Cardiff University, and Cambridge University, have identified a chemical pathway by which life could neutralize Venus' acidic environment, creating a self-sustaining, habitable pocket in the clouds.

Within Venus' atmosphere, scientists have long observed puzzling anomalies -- chemical signatures that are hard to explain, such as small concentrations of oxygen and nonspherical particles unlike sulfuric acid's round droplets. Perhaps most puzzling is the presence of ammonia, a gas that was tentatively detected in the 1970s, and that by all accounts should not be produced through any chemical process known on Venus.

In their new study, the researchers modeled a set of chemical processes to show that if ammonia is indeed present, the gas would set off a cascade of chemical reactions that would neutralize surrounding droplets of sulfuric acid and could also explain most of the anomalies observed in Venus' clouds. As for the source of ammonia itself, the authors propose that the most plausible explanation is of biological origin, rather than a nonbiological source such as lightning or volcanic eruptions.

As they write in their study, the chemistry suggests that "life could be making its own environment on Venus."

This tantalizing new hypothesis is testable, and the researchers provide a list of chemical signatures for future missions to measure in Venus' clouds, to either confirm or contradict their idea.

"No life that we know of could survive in the Venus droplets," says study co-author Sara Seager, the Class of 1941 Professor of Planetary Sciences in MIT's Department of Earth, Atmospheric and Planetary Sciences (EAPS). "But the point is, maybe some life is there, and is modifying its environment so that it is livable."

The study's co-authors include Janusz Petkowski, William Bains, and Paul Rimmer, who are affiliated with MIT, Cardiff University, and Cambridge University.

Life suspect

"Life on Venus" was a trending phrase last year, when scientists including Seager and her co-authors reported the detection of phosphine in the planet's clouds. On Earth, phosphine is a gas that is produced mainly through biological interactions. The discovery of phosphine on Venus leaves room for the possibility of life. Since then, however, the discovery has been widely contested.

"The phosphine detection ended up becoming incredibly controversial," Seager says. "But phosphine was like a gateway, and there's been this resurgence in people studying Venus."

Inspired to look more closely, Rimmer began combing through data from past missions to Venus. In these data, he identified anomalies, or chemical signatures, in the clouds that had gone unexplained for decades. In addition to the presence of oxygen and nonspherical particles, anomalies included unexpected levels of water vapor and sulfur dioxide.

Rimmer proposed the anomalies might be explained by dust. He argued that minerals, swept up from Venus' surface and into the clouds, could interact with sulfuric acid to produce some, though not all, of the observed anomalies. He showed the chemistry checked out, but the physical requirements were unfeasible: A massive amount of dust would have to loft into the clouds to produce the observed anomalies.

Seager and her colleagues wondered if the anomalies could be explained by ammonia. In the 1970s, the gas was tentatively detected in the planet's clouds by the Venera 8 and Pioneer Venus probes. The presence of ammonia, or NH3, was an unsolved mystery.

"Ammonia shouldn't be on Venus," Seager says. "It has hydrogen attached to it, and there's very little hydrogen around. Any gas that doesn't belong in the context of its environment is automatically suspicious for being made by life."

Livable clouds

If the team were to assume that life was the source of ammonia, could this explain the other anomalies in Venus' clouds? The researchers modeled a series of chemical processes in search of an answer.

They found that if life were producing ammonia in the most efficient way possible, the associated chemical reactions would naturally yield oxygen. Once present in the clouds, ammonia would dissolve in droplets of sulfuric acid, effectively neutralizing the acid to make the droplets relatively habitable. The introduction of ammonia into the droplets would transform their formerly round, liquid shape into more of a nonspherical, salt-like slurry. Once ammonia dissolved in sulfuric acid, the reaction would trigger any surrounding sulfur dioxide to dissolve as well.

The presence of ammonia then could indeed explain most of the major anomalies seen in Venus' clouds. The researchers also show that sources such as lightning, volcanic eruptions, and even a meteorite strike could not chemically produce the amount of ammonia required to explain the anomalies. Life, however, might.

In fact, the team notes that there are life-forms on Earth -- particuarly in our own stomachs -- that produce ammonia to neutralize and make livable an otherwise highly acidic environment.

"There are very acidic environments on Earth where life does live, but it's nothing like the environment on Venus -- unless life is neutralizing some of those droplets," Seager says.

Scientists may have a chance to check for the presence of ammonia, and signs of life, in the next several years with the Venus Life Finder Missions, a set of proposed privately funded missions, of which Seager is principal investigator, that plan to send spacecraft to Venus to measure its clouds for ammonia and other signatures of life.

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