It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Tuesday, August 03, 2021
Researchers are first in the world to watch plants 'drink' water in real-time
The conversion of high-intensity green light into bio-friendly red wavelengths, within the Titanium:Sapphire laser used in the study. Credit: University of Nottingham
The inability to monitor water uptake inside roots—without damaging the specimen—has been a key stumbling block for researchers seeking to understand the motion of fluids in living plant cells and tissues.
Study lead, Dr. Kevin Webb from the Optics and Photonics Research Group, explains, "To observe water uptake in living plants without damaging them, we have applied a sensitive, laser-based, optical microscopy technique to see water movement inside living roots non-invasively, which has never been done before.
"Fundamentally, the process by which plants are able to thrive and become productive crops is based on how well it can take up water and how well it can manage that process. Water plays an essential role as a solvent for nutrients, minerals and other biomolecules in plant tissues. We've developed a way to allow ourselves to watch that process at the level of single cells. We can not only see the water going up inside the root, but also where and how it travels around.
"Feeding the world's growing population is already a problem. Climate change is causing huge shifts in the pattern and density of waterfall on the planet which leads to problems growing crops in regions hit by floods or droughts. By selecting plants that are better at coping with stress, the goal is to increase global food productivity by understanding and using plant varieties with the best chances of survival that can be most productive in any given environment, no matter how dry or wet."
How it works
For the study, water transport measurements were performed on the roots of Arabidopsis thaliana, which is a 'model plant' for scientists since they can be easily genetically-engineered to interfere with basic processes like water uptake.
Using a gentle laser, the new imaging technique—based on the Nobel Prize-winning Raman scattering technique—allowed researchers to measure water traveling up through the root system of Arabidopsis at the cellular level, and to run a mathematical model to explain and quantify this.
The researchers used 'heavy' water (deuterium oxide, or D2O), which contains an extra neutron in the nucleus of each hydrogen atom. By scanning a laser in a line across the root while the plant drank, it was possible to see the 'heavy' water moving past via the root tip.
In Arabidopsis that had been genetically-altered to compromise its water uptake, these measurements—combined with the mathematical model—revealed an important water barrier within the root. This confirmed for the first time that water uptake is restricted within the central tissues of the root, inside of which the water vessels are located.
Co-lead, Malcolm Bennett, Professor of Plant Sciences at the University, said, "This innovative technique is a real game-changer in plant science—enabling researchers to visualize water movement at a cell and second scale within living plant tissues for the very first time. This promises to help us address important questions such as—how do plants 'sense' water availability? Answers to this question are vital for designing future crops better adapted to the challenges we face with climate change and altered weather patterns."
The findings of this Leverhulme Trust-funded study, are published in the journal Nature Communications in a paper titled: "Non-invasive hydrodynamic imaging in plant roots at cellular resolution."
Future applications
While developing the method, the research initially focused on plant cells, which are about 10 times the size of human cells and therefore more easily observed. The research team is currently porting these same methods to human cells to understand exactly the same kinds of processes at an even smaller scale.
Just as with plants, there are tissues in the human body responsible for handling water, which is crucial to function. Transparent tissues of the eye, for example, can suffer from diseases of fluid handling which include ocular lens cataracts; macular degeneration and glaucoma. In future, the new Raman imaging technique could become a valuable healthcare monitoring and detection tool.
Next steps
The researchers are working towards a commercial path for their hydrodynamic Raman imaging technique, and have just applied for funding with four UK and EU agriculture companies to look at tracers that move from plant leaves to roots to understand both directions of water transport. In parallel, the team is working on portable versions of the technology to allow water transport measurements to be taken into the field by farmers and scientists to monitor water handling in crops growing in challenging local environments.
The research team is currently bidding for a European Research Council Synergy Grant with partners in the EU and UK to take the study of water uptake and drought resistance towards being a new tool to help choose and understand how particular crops can be matched to particular local growth conditions
More information:Flavius C. Pascut et al, Non-invasive hydrodynamic imaging in plant roots at cellular resolution,Nature Communications(2021).DOI: 10.1038/s41467-021-24913-z
In Manhattan's Terminal Warehouse, Lamont-Doherty Earth Observatory tree-ring lab director Edward Cook extracts a straw-width core from a standing wooden beam. Credit: Caroline Leland
In the popular imagination, New York City is a mass of soaring steel-frame skyscrapers. But many of the city's 1 million buildings are not that modern. Behind their brick-and-mortar facades, its numerous 19th- and early 20th-century warehouses, commercial buildings and row homes are framed with massive wooden joists and beams. These structures probably harbor at least 14 million cubic meters of timber, the volume equivalent of about 74,000 subway cars. Their main sources: old-growth forests that long predated New York, and were erased to create it.
Historic preservation has never been New York's strong point; about 1,000 old buildings are demolished or gut-renovated every year, the remains mostly going to landfills. Now, a team from the Tree Ring Laboratory at Columbia University's Lamont-Doherty Earth Observatory is harnessing the destruction to systematically mine torn-out timbers for data. Annual growth rings from trees that were young in the 1500s may offer records of past climate no longer available from living trees. Studies of timber species, ages and provenances can shed light on the history of U.S. logging, commerce and transport.
"New York City is a huge repository of old timbers, probably the biggest in the country. It's an amazing resource for science," said dendrochronologist (tree-ring scientist) Mukund Palat Rao, one of the leaders of the effort (his position at Lamont is sponsored by the National Oceanic and Atmospheric Administration). "These forests don't exist anymore—they're inside the buildings. They're being demolished at a rapid pace, and getting thrown away. We're trying to collect whatever we can."
After its settlement by the Dutch in the 1620s, New York grew steadily but slowly. Then, about 1840, great waves of immigrants began arriving. A resulting major growth spurt lasted some 80 years before tapering off. During this time, much of the now existing city was built. Before steel came in during the early 20th century, the framing material of choice was wood. Starting in the 1700s, loggers to the north cut vast swaths of white pine, spruce, hemlock and balsam fir, often floating it down the Hudson River. By the latter 1800s, three-quarters of the Northeast's virgin forests were stripped. Many builders then looked to the vast old-growth longleaf pine ecosystems of the U.S. Southeast. When the eastern seaboard was exhausted, loggers moved on to Louisiana, Mississippi and Texas. Today, only about 3 percent of the South's old longleaf forests remain.
In a study just published in the Journal of Archaeological Science: Reports, the researchers shed unprecedented light on this period. The study looks at joists taken from Manhattan's gigantic 1891 Terminal Warehouse, an iconic structure that still occupies an entire block in Manhattan's Chelsea neighborhood. Early on, it stored everything from carpets, furs and liquor to Broadway stage sets and stone sarcophagi. In the 1980s, it was converted into the country's largest mini-storage facility. A run of railroad tracks bisecting its cavernous interior became for more than a decade the site of the infamously decadent Tunnel nightclub. The warehouse has also served as a spooky set for movies including the "Ghostbusters" series.
In 2019, new owners wanted to open up space for new shops, offices and restaurants. This involved pulling out enormous wooden joists holding up some interior sections of the building. Hoping to reuse the joists, they called Edward Cook, head of the Tree Ring Lab, to see what could be learned about them.
Cook is a hero of archaeodendrochronology, the study of wood from old buildings. Early in his career, his examinations of Philadelphia's Independence Hall and other historic structures showed that their ages could be pinned down by studying tree rings in their framing. He has since dated about 150 old houses and other buildings across the Northeast. In 2014, he and colleagues analyzed the remains of a wooden sloop accidentally turned up during excavations at the destroyed World Trade Center site. They determined it had been built from old-growth white oak cut somewhere near Philadelphia around 1773, and served for 20 or 30 years before being dumped on the mucky shoreline of New York harbor.
The tree-ring lab crew went down to the Terminal Warehouse's massive basement. Here, they found piles of removed joists, 22 feet long, a foot wide and 3 inches deep. Looking at the ends in cross section, they could see that many displayed 150 or more annual growth rings—a dendrochronologist's delight. (Caroline Leland, the study's lead author with Rao, also noted several humongous bird-cage-like things—tools of the trade once used by go-go dancers at the Tunnel, she guessed.) Amid combustion fumes and deafening racket, a building worker chainsawed off the ends of a couple of dozen of the best-looking joists, and the scientists took them back to the lab.
Section of a beam from the now-demolished 1892 St. Mary's Church in Clinton Hill, Brooklyn. Credit: Kevin Krajick/Earth Institute
Based on resin content and certain patterns and colors in the timbers' rings, the team determined that the joists were perfect specimens of old-growth longleaf pine, prized by 19th-century builders for their density, strength and resistance to rot.
Trees' growth rings vary each year according to weather; in the simplest translation, wider rings mean wetter years with good growing conditions. After that, it gets more complicated; by measuring and comparing rings in excruciating detail, dendrochronologists can create a year-by-year fingerprint that most or all of the trees from the same place have in common. The joists came from different parts of different trees, so no two represented the exact same time span. But many overlapped in time. This allowed the scientists to assemble a master chronology, from the date the oldest trees started growing to the date they were cut.
Based on the characteristics of some of the joists' outer rings, the scientists determined that most of the trees had been felled in 1891or a bit earlier. And, all the trees were ancient; most started out as saplings anywhere from the early 1600s to the mid-1700s. The oldest had sprouted around 1512.
They then compared their data to previous studies of rings in rare living longleaf stands, ranging from Louisiana to North Carolina. Because yearly conditions vary from site to site, each site exhibits localized ring patterns. By comparing these, they were then able to deduce where the timbers had come from: The rings from the joists lined up nicely with those of living trees from eastern Alabama's Choccolocco Mountain and Spreewell Bluff, just across the border in western Georgia. Both areas had been heavily logged in the late 1800s, when steam power and rail networks were expanding mightily, allowing lumber to be shipped to ravenous faraway markets like New York.
The ca. 1891 Terminal Warehouse, in Manhattan's Chelsea neighborhood, in 2020. The scientists began their investigations here. Credit: Mukund Palat Rao
Delving into regional historical archives, the team hypothesized that the trees were sawed at the Sample Lumber Company, near Hollins, Alabama. Then, in one of a couple of possible scenarios, they would have been shipped by a series of connecting railroads to the port of Savannah, Ga. There, the 250-pound joists would have been loaded into openings in the hulls of schooners bound for the banks of the Hudson, where the Terminal Warehouse was rising.
"To think of all those old trees, just clear cut—that was really sad," said Leland. On the other hand: "There is a lot of history locked up in those timbers. It's really difficult to find living old growth in the eastern United States now. If we can get enough samples, it may allow us to develop a better understanding of the long-term climate in the regions these trees come from."
The scientists now wanted more old timbers. Luckily, they had a connection with Alan Solomon, a New York entrepreneur and polymath. Solomon comes from a family of scrap-metal dealers, so he knows salvage. He is also an intensely driven historical researcher and preservationist. Among other pursuits, he fought for seven years in the late 1990s and early 2000s to stop the demolition of 211 Pearl Street, a circa 1831 commercial building in lower Manhattan commissioned by soapmaker William Colgate. (Yes, that Colgate, progenitor of the Colgate-Palmolive mega-corporation.) Solomon had heard that New York writer Herman Melville might have written his famous 1853 short story "Bartleby the Scrivener" at 211 Pearl. This may or may not have been true. In the end, the building was destroyed and replaced by a skyscraper. A salvager carted away some of the timbers and sold them for reuse in other buildings, including a hotel in New Hampshire.
By 2019, Solomon was running his own Brooklyn-based timber-salvage company, Sawkill Lumber. (Named after a creek that once ran from the present-day site of the American Museum of Natural History to the East River. It powered an early 1600s Dutch sawmill that probably helped devour the old-growth forest of Manhattan itself.) Solomon also authored a book about reclaimed wood, for which he consulted Ed Cook. After that, Solomon ended up helping with historical research for the Terminal Warehouse project. With his finger on the pulse of New York demolitions, he was more than happy to have the dendrochronologists tag along with him to active sites and saw out samples as walls were being taken down and workers piled up debris.
In the Terminal Warehouse basement, tree-ring scientists and building staff inspect original joists that were removed from a section of the building during a renovation. Some had more than 150 visible annual rings. Caroline Leland, who co-led study of the building, is at center, back to the camera. Credit: Mukund Palat Rao
Among other places, they showed up with their own chainsaws and hardhats to the remodeling of an 1898 firehouse on Manhattan's Lafayette Street; a couple of doomed horse stables in Brooklyn; the 19th-century St. Mary's Church in Brooklyn's Clinton Hill neighborhood, which was coming down for a modern development; and various warehouses, homes and mixed-use building scattered around the city. So far, they have material from 18 buildings, and plan to collect more.
The one other site they have analyzed so far is 211 Pearl; Solomon had hung on to some of the remains. They identified the framing as white pine. They then compared the timbers to studies of rare living white pines from Pennsylvania, upstate New York and Quebec, and found the best match in New York's Adirondack Mountains. Here, they learned, the pines had once grown as much as four feet in diameter and 160 feet tall. Logging had started in the 1750s and peaked in the 1870s, with much of the wood being sawed in the upstate town of Glens Falls, and sent down to New York.
The living-tree studies to which the researchers compared the Pearl Street timbers extended back to 1690—quite a respectable stretch. But some of the Pearl Street timbers were even older: 1532. If more such specimens can be found, said Rao, this should allow the scientists to extend the climate record for this region considerably. Interestingly, the trees appear to have been cut in 1789, four decades before 211 Pearl went up. Were they stockpiled? Or, perhaps recycled from an even earlier building?
The dendrochronologists have now joined with Solomon to try founding a nonprofit aimed at promoting the preservation of old timbers in New York. They are also talking with a small group of engineers and architects who want to lobby the city for an ordinance that would identify old timbers uncovered in demolitions, and require companies to contact salvagers.
"I'd like to see information from a big network of buildings," said Leland. "We could develop a sort of history of the urban forest."
Former University of Delaware postdoctoral research fellow Carl Rosier poses with 300-year-old American Beech Tree. Credit: University of Delaware
If you're a tree, country life is much easier than city living. Rural trees—which can live long, productive lives of sometimes more than 100 years—draw on vast resources of an extensive forest network of nearby trees. In urban areas, friendly, neighboring trees can be few and far between. Heat island effects and variation in nutrient levels leave urban trees more vulnerable to natural environmental pressures. The consequences are depressed growth and an early death.
But underneath the tree lies an ally—soil, which provides the tree a welcome anchor for its roots, nutrients for growth and a vast array of soil microbes. In return, trees modify the soil microbial community (SMC), establishing and nourishing crucial bacterial and fungal life below the surface.
In a research article published in Scientific Reports, University of Delaware researchers investigated the pressures of urbanization on SMC associated with specific tree species. The research team included UD faculty member Tara Trammell and former postdoctoral research fellow Carl Rosier.
The research team compared urban, suburban and rural areas. They selected American beech and yellow poplar trees due to canopy and bark differences, but also because of their dominance in both urban and rural forests.
To characterize the soil microbes beneath specific trees, Trammell and Rosier used next generation high throughput sequencing. This technique enabled the researchers to simultaneously sequence millions of DNA molecules allowing specific identification of hundreds of bacterial species. In tandem with this approach, the research team also investigated soil carbon, nitrogen, metal concentrations and pH that comprise the soil under each tree species across all sampled forests. The team's findings suggest urban pressure alters specific soil characteristics, overriding the tree's capacity to maintain a unique SMC.
Carl Rosier and field assistant Gavin Rosier contemplate the day’s sampling efforts. Credit: University of Delaware
In rural forests, the researchers found SMC dissimilarity, suggesting that microbes are unique to each tree species. However, city life means greater urbanization pressure, so whether the tree is a beech or poplar, SMC is similar. Rosier said similarity is not the result of biodiversity loss, but rather due to greater overlap of shared organisms.
"We thought that we would lose some of the more sensitive microorganism species within urban environments, but we didn't see that," said Rosier. "The [urban] environment changes SMC to a degree where you have beech and poplar trees with similar SMC composition."
With expanding population centers, the study will inform land managers and conservation efforts on how to create more resilient urban forests. Such forestry research illuminates a battle plan for how big an urban forest must be to positively impact ecosystem services.
The tree-soil bond
Pulling carbon from the air and transferring it through their roots and leaf litter, trees are soil's best friend, replenishing soil with rich sources of organic nutrients. These selfless exploits help to create a healthy SMC, which in turn provide critical ecosystem services, including organic matter decomposition, soil structural formation and nutrient cycling.
Carl Rosier collects a one-meter soil core. Credit: University of Delaware
"When we think about climate change and the ability of soil to sequester carbon, microbes are essential in that process," said Rosier, now a senior project scientist with Material Matters and lead research scientist and co-founder of Agroecology Solutions.
Without the trees to provide critical resources, the soil's composition would change, negatively altering an ecosystem. Plants develop specific communities of microbes around their roots. Sometimes living hundreds of years, trees spend their life manipulating water, nutrients and other factors like pH in the soil.
"At the base of specific species of trees, you have a unique soil chemistry; however, as little as one meter away, soil chemistry can differ significantly," said Rosier.
Soil versus city
You might expect rural and urban soil chemistry to be very different. After all, an urban forest faces a lot of human-made environmental pressures. Instead, the chemistry is similar in both locations—very robust and resilient.
Carl Rosier and Gavin Rosier prepare soil samples for soil chemistry analysis. Credit: University of Delaware
In the soil versus city struggle, a casual observer might not give soil much of a chance. But despite being outnumbered by human-made elements, the underdog pulls a Rocky Balboa, fighting deep into the night.
"It shows you how robust soils are," said Rosier. "Soils can take a huge impact before losing organic matter and the ability to sustain plant life."
But once the soil crosses the tipping point where it loses important components such as organic matter, nursing it back to health is incredibly difficult.
"As land managers and stewards of the land, we must be mindful of this critical juncture," Rosier said. "The capacity of soils to perform ecosystem services is critical for humans to survive on our planet."Compost improves apple orchard sustainability
More information:Carl L. Rosier et al, Urbanization pressures alter tree rhizosphere microbiomes,Scientific Reports(2021).DOI: 10.1038/s41598-021-88839-8
Crew members of the eXXpedition Round the World voyage clear plastics from a beach during Leg 5 of the voyage between Aruba and San Blas, Panama. Credit: Sophie Dingwall/eXXpedition
The Caribbean is renowned globally for its stunning beaches and crystal clear ocean.
That is according to a new study, the first holistic assessment of marine and land-based plastic pollution in the Southern Caribbean and some of the environmental and human factors which might influence its distribution.However, its islands and the surrounding sea are being contaminated by plastics and other manmade fibers, posing a potential future threat to its diverse marine life and the tourism industry on which its economy depends.
The study is the result of sample analysis from a pioneering all-female Round the World sailing mission led by eXXpedition. Samples were collected in late 2019 from the seas and seafloor, and from land-based assessments.
Off the coast of five Caribbean countries, it identified 18 different polymers of plastic—including, synthetic fibers, paint flakes and acrylics—in waters across the Caribbean, with the highest concentrations (5.09 particles per m³) located off the San Blas islands in Panama.
Detailed ocean modeling and an assessment of regional policies indicated the abundance of microplastics in the area likely arose from a combination of distant sources carried by ocean currents and run-off from mainland Panama, which has some of the highest estimated levels (around 44%) of mismanaged waste in the region.
Crew members from the eXXpedition Round the World voyage collect plastic samples from the ocean on the leg between Antigua and Aruba. Credit: Jamie Colman/eXXpedition
By contrast, the waters off Antigua, Bonaire and Colombia had lower quantities of terrestrial and marine plastics. Antigua, in particular, had a high diversity of polymers, with the research suggesting the majority of the microplastics collected were likely to have been transported by currents generated in the wider North Atlantic Ocean, even originating in the so-called North Atlantic garbage patch.
Writing in Science of the Total Environment, the study's authors suggest both terrestrial litter and the microplastics identified in marine samples may arise from the maritime and tourism industries.
That in turn, they say, represents the complex challenges of managing plastic pollution since both are major contributors to the economies of the Caribbean region.
The research was led by scientists at the University of Plymouth (UK) in conjunction with the University of Georgia (U.S.), Plymouth Marine Laboratory (UK) and the Technological University of Panama.
Dr. Winnie Courtene-Jones, eXXpedition Science Lead and Post-Doctoral Research Fellow in the International Marine Litter Research Unit at the University of Plymouth, is the study's lead author. She said: "Until now, evidence of the abundance of plastics within the Caribbean has been lacking. This study presents a snapshot of plastic pollution, and how it differs—in quantity, nature, origin and the policies in place to manage it—across the south of the region. It contributes towards the void of knowledge regarding marine plastic pollution in the Caribbean Sea but also highlights the need for international and interdisciplinary collaborative research and solutions to plastic pollution."
The S.V. TravelEdge moored off Antigua during the eXXpedition Round the World voyage. Credit: Lara Hoad/eXXpedition
eXXpedition's Round the World voyage left Plymouth in October 2019 to visit some of the most important and diverse marine environments on the planet with the aim of inspiring a network of changemakers, informing effective solutions with industry and influencing policy change on land.
Emily Penn BEM, eXXpedition Founder and one of the co-authors on the current study, said: "Our vision for eXXpedition Round the World was to explore remote and inaccessible parts of the planet to pinpoint where the solutions to plastic pollution lie on land by better understanding the sources. The surprising thing from our discoveries is the huge diversity of polymer types which means the pollution has come from many different sources and as a result means the solutions need to be diverse too. We all share one planet and wherever we live the ocean connects us—this study demonstrates why for any game-changing action to tackle ocean plastic pollution all sectors of the community must come together in a holistic way across the Caribbean region and beyond."
The University of Plymouth was the first to highlight the global problem of marine microplastics—earning the Queen's Anniversary Prize for Higher and Further Education in 2019—and was recently named the leading university in the world for marine research and teaching.
Professor Richard Thompson OBE, Head of the International Marine Litter Research Unit and senior author on the study, added: "It is now very clear that plastic litter presents a global environmental problem. There are changes we can all make in our everyday lives to help address that challenge. However, it is only by gaining a better understanding of how plastic debris passes from its source to the ocean that we will be fully equipped to tackle the problem."Systemic change to the entire plastics economy is needed to halt ocean plastic pollution
More information:Winnie Courtene-Jones et al, Source, sea and sink—A holistic approach to understanding plastic pollution in the Southern Caribbean,Science of The Total Environment(2021).DOI: 10.1016/j.scitotenv.2021.149098
Plastics sustainability has come a long way in recent years thanks in large part to scientific advances. But even as plastics become more and more environmentally friendly, the world continues to be polluted as many industries rely on them for their widely used products.
The latest research from Dr. Junpeng Wang, assistant professor in UA's School of Polymer Science and Polymer Engineering has a solution to reduce such waste and clear a scientific pathway for a more sustainable future that can appeal to the rubber, tire, automobile and electronics industries. Although this work is supported by UA, Wang recently earned a prestigious National Science Foundation CAREER Award that will support future developments from this research.
The problem at hand: Synthetic polymers, including rubber and plastics, are used in nearly every aspect of daily life. The dominance of synthetic polymers is largely driven by their excellent stability and versatile mechanical properties. However, due to their high durability, waste materials composed of these polymers have accumulated in the land and oceans, causing serious concerns for the ecosystem.
In addition, since over 90% of these polymers are derived from finite natural resources, such as petroleum and coal, the production of these materials is unsustainable if they cannot be recycled and reused.
A promising solution to address the challenges in plastics sustainability is to replace current polymers with recyclable ones in order to achieve a circular use of materials. Despite the progress made thus far, few recyclable polymers exhibit the excellent thermal stability and high-performance mechanical properties of traditional polymers. The recyclable materials Wang and his team have developed are unique in the superior thermal stability and versatile mechanical properties. Their article explaining the research, "Olefin Metathesis–Based Chemically Recyclable Polymers Enabled by Fused-Ring Monomers," was published last week by Nature Chemistry.
"We are particularly interested in chemically recyclable polymers that can be broken down into the constituents (monomers) from which they are made," says Wang. "The recycled monomers can be reused to produce the polymers, allowing for a circular use of materials, which not only helps to preserve the finite natural resources used in plastics production, but also addresses the issue of unwanted end-of-life accumulation of plastic objects."
The key in the design of chemically recyclable polymers is to identify the right monomer. Through careful computational calculation, the researchers identified a targeting monomer. They then prepared the monomer and polymers through chemical synthesis, using abundantly available starting materials.
Wang's research group, including polymer science graduate students and a postdoctoral scientist, aims to address those challenges by developing polymers that can be broken down into their constituent parts. When the catalyst for depolymerization is absent or removed, the polymers will be highly stable and their thermal and mechanical properties can be tuned to meet the needs of various applications.
"The chemically recyclable polymers we developed show excellent thermal stability and robust mechanical properties and can be used to prepare both rubber and plastics," says Wang. "We expect this material to be an attractive candidate to replace current polymers. Our molecular design is guided by computation, highlighting the transformational power of integrating computation and experimental work. Compared to other recyclable polymers that have been demonstrated, the new polymers we demonstrate show much better stability and more versatile mechanical properties. When a catalyst is added, the polymer can be degraded into the constituent monomer for recycling."
Next for Wang's research group is to expand the scope of the chemically recyclable polymers and to develop carbon-fiber reinforced polymer composites. The team will also analyze the economic performance of this industrial process and life-cycle analysis for commercialization of the polymers.
Hundreds of thousands of people around the world die too soon every year because of exposure to air pollution caused by our daily use of chemical products and fuels, including paints, pesticides, charcoal and gases from vehicle tailpipes, according to a new CU Boulder-led study.
The new work, led by former CIRES postdoctoral researcher Benjamin Nault and CIRES Fellow Jose-Luis Jimenez, calculated that air pollution caused by "anthropogenic secondary organic aerosol" causes 340,000-900,000 premature deaths. Those are tiny particles in the atmosphere that form from chemicals emitted by human activities.
And "that's more than 10 times as many deaths as previously estimated," said Nault, who is now a scientist at Aerodyne Research, Inc. His work, published today in Atmospheric Chemistry and Physics, builds on findings by CU Boulder, NOAA, NASA, and others that emissions from everyday products are increasingly important in forming pollutants in urban air.
"The older idea was that to reduce premature mortality, you should target coal-fired power plants or the transportation sector," Nault said. "Yes, these are important, but we're showing that if you're not getting at the cleaning and painting products and other everyday chemicals, then you're not getting at a major source."
Atmospheric researchers have long understood that particles in the atmosphere small enough to be inhaled can damage people's lungs and increase mortality. Studies have estimated that fine particle pollution, often called PM2.5, leads to 3-4 million premature deaths globally per year, possibly more.
Many countries, including the United States, therefore have laws limiting how many of those particles get into the atmosphere. We regulate soot from power plants and diesel exhaust, for example, which are "direct" sources of particulate matter. And regulations also target fossil fuel emissions of sulfur and nitrogen oxides, which can react in the atmosphere to form fine particles—an indirect, "secondary inorganic" source of particles.
The new work suggests that a third broad category of chemicals—anthropogenic secondary organic pollutants—is a significant indirect source of deadly fine particles.
To determine the mortality impact of several sources of fine particles, the team dug into data from 11 comprehensive air quality studies carried out in cities around the world in the last two decades. They drew on detailed databases of chemical emissions from cities including Beijing, London and New York City, and they ran those numbers through sophisticated air quality models that also incorporate satellite data.
They found that the production of secondary organic aerosol in those 11 cities was strongly correlated with specific organic compounds emitted by people's activities. The chemicals at issue—called aromatics and intermediate- and semi-volatile organic compounds—are emitted from tailpipes and cooking fuels like wood and charcoal, and increasingly also from industrial solvents, house paints, cleaning products and other chemicals.
In previous work in Los Angeles, CIRES, NOAA and other scientists have reported that such volatile chemical products contribute as much as vehicles do to the formation of particle pollution. "What's new here," said co-author Brian McDonald, a NOAA scientist, "is that we are showing this is an issue in cities on three continents, North America, Europe and east Asia."
Air quality regulations have tended to focus on volatile chemicals that produce ozone, another hazardous pollutant, said Jimenez, who is also a professor of chemistry at CU Boulder. But it is increasingly clear, most recently from the new work, that chemicals which contribute little to ozone formation may still contribute seriously to particle formation.
"Because this effect has been thought to be small, it hasn't been targeted for control," Jimenez said. "But when you take the atmospheric chemistry into account and put it into a model, you find that this particular source is killing a lot of people."
Nault and Jimenez said they hope to expand their work to include more urban areas of the world, where there haven't been enough measurements yet to confirm that volatile chemical products contribute substantially to fine particles. But the trend is holding so far in all places where there are enough measurements.
More information: Benjamin A. Nault et al, Secondary organic aerosols from anthropogenic volatile organic compounds contribute substantially to air pollution mortality, Atmospheric Chemistry and Physics (2021). DOI: 10.5194/acp-21-11201-2021
Northrop Grumman’s Cygnus spacecraft atop the company’s Antares rocket lifts off Feb. 20, 2021, to deliver important science and cargo to the International Space Station on the company’s 15th commercial resupply services mission for NASA. Credits: NASA
A research team at Oak Ridge National Laboratory have 3D printed a thermal protection shield, or TPS, for a capsule that will launch with the Cygnus cargo spacecraft as part of the supply mission to the International Space Station. The launch will mark the first time an additively manufactured TPS has been sent to space.
Scientists worked with NASA to develop materials designed to withstand extreme temperatures encountered when objects reenter the atmosphere. The TPS protects a basketball-sized capsule that was developed by the University of Kentucky as a testbed for entry system technologies.
"This is an opportunity to gain flight experience on new materials," ORNL's Greg Larsen said. "Additive manufacturing enables automated, rapid production and opens up new design opportunities for using lightweight materials in spacecraft."
Equipped with sensors that record and transmit data to monitor performance, the capsule is anticipated to return to earth before the end of 2021.
Play
A 3D printed thermal protection shield, produced by ORNL researchers for NASA, is part of a cargo spacecraft bound for the International Space Station. The shield was printed at the Department of Energy’s Manufacturing Demonstration Facility at ORNL. Credit: ORNL, U.S. Dept. of Energy
View of the corner of the test room with radiator. Credit: Fraunhofer-Gesellschaft
Climate change is causing a persistent increase in the number of hot summer days. Offices and homes are getting hotter, and the nights bring little respite from the heat. Against this backdrop, a significant increase in new cooling systems installations is anticipated, which in turn will give rise to increased energy consumption. One potential cost-effective alternative is to use existing heating systems. According to an analysis by the Fraunhofer Institute for Building Physics IBP, the heat pumps in these systems can be reverse operated to provide effective cooling.
Global energy consumption from air conditioning systems continues to rise. According to information from the International Energy Agency (IEA), the total energy used to cool residential and office buildings in 2016 was around 2000 terawatt hours. That is an estimated 10 percent of the world's total power consumption. This amount could triple by 2050: By then, ten air conditioning systems will be sold every second. In Germany, experts expect energy consumption for cooling residential buildings to double over the next 20 years. For non-residential buildings, the German Environment Agency expects an increase of 25 percent.
How can this expected surge in new cooling system installations be prevented? This is the issue being addressed by a team of researchers at Fraunhofer IBP. "In existing buildings, if a heat pump—i.e. the heat generator—that is already installed can be reverse operated to provide air conditioning, the same system that is already being used for heating could be used for cooling as well," says Sabine Giglmeier, a scientist at Fraunhofer IBP. This would remove the need to purchase new cooling systems and save energy.
Assessment of the potential of radiators and underfloor heating systems
To assess the extent to which this technology can be used to avoid overheating in summer, the engineer and her team assessed the potential of two heating systems: They investigated whether radiators and underfloor heating systems—heat distributors—could replace the air conditioning units that are often used in existing buildings. These units dissipate their waste heat via a tube through the window or an opening in the wall.
As part of the trial, the researchers collected a large amount of indoor climate data, which they then used to validate the digital twin. Credit: Fraunhofer-Gesellschaft
"Not only do these air conditioning systems use a lot of power, they are also loud and create drafts. They can also cause hygiene problems if they are not properly maintained," explains the researcher.
Simulations with WUFI Plus
To determine whether heat pumps can be combined with radiators or underfloor heating systems for use as a cooling system, the researcher and her team conducted initial tests under laboratory conditions in the climate chamber with radiators and underfloor heating systems. Digital twins of the heating systems were then tested using the building simulation software WUFI Plus to determine whether the laboratory measurements matched the software calculations. "We can use the digital twins to produce a valid representation of reality and calculate the effect of the overall system in a wide range of application scenarios. This allows us to identify the specific areas where heat pumps plus radiators or underfloor heaters are most effective." The simulation software creates a (hygric) link between heat and humidity in the calculation. The simulations can be scaled to any type of building, taking into account a range of parameters such as room and window size, the size of the heating elements, the external temperature and the design and number of windows. The researchers can examine other parameters, such as energy requirements and comfort. This allows for a comprehensive evaluation of heating and cooling systems.
Infographic: Cooling in summer with heating systems. Credit: Fraunhofer-Gesellschaft
The tests found that both radiators and underfloor heating systems have the potential to reduce the ambient air temperature in the summer significantly and to produce a pleasant cooling effect in office spaces with a standard size of 16 m2, windows of up to 3 m2 and two workers, without unwanted condensation forming on cold surfaces. The inflow temperature of the system must be regulated depending on the dew point of the ambient temperature in order to avoid structural damage from condensation. "The dew point temperature is a critical figure that we need to take into account in our calculations. This is because moisture condenses on a surface when the surface is colder than the dew point temperature of the air. This is why it is important to consider the dew point temperature when cooling. In other words, if the dew point temperature is 13 degrees Celsius, the water we feed through the heating system cannot be any colder than that, otherwise the water from the air will condense on the heating element and supply lines, causing damp."
Up to 65 percent reduction in over temperature degree hours
Another important criterion for the calculations is over temperature degree hours. This unit of measurement refers to the number of hours and kelvins above the limit temperature of the room, which is 26 degrees Celsius, in the year. A maximum of 1200 over temperature degree hours per year are permitted in residential buildings, and just 500 in offices. The researchers' calculations showed a reduction of over 40 percent in over temperature degree hours for radiators measuring 70 cm by 1 m. For radiators twice that size, a 65 percent reduction can be achieved compared to an uncooled room.
"All in all, we demonstrated that the cooling performance achieved using radiators is sufficient with a moderate window surface area share. However, a higher window surface area share requires a larger cooling area to achieve comfortable indoor climate conditions. This area can be provided using underfloor heating systems, which also produce a significantly greater cooling effect, as our tests have shown," says Giglmeier in summary. Heat pumps with cooling functions could be an alternative to expensive cooling systems in existing buildings.
