Green roofs are worth the cost for urban residents

Peer-Reviewed Publication

UNIVERSITY OF ILLINOIS COLLEGE OF AGRICULTURAL, CONSUMER AND ENVIRONMENTAL SCIENCES

 

IMAGE: GREEN ROOFTOPS IN PORTLAND, OREGON view more 

CREDIT: NOELWAH NETUSIL.

URBANA, Ill. ­– Plant-covered roofs have become a regular sight in Portland, Oregon. The city is a leader in incorporating green infrastructure for stormwater management, including free street trees, rebates for small residential housing footprints, and green roofs.

Green roofs, also known as rooftop gardens or ecoroofs, typically have a layer of plants growing in soil on top of the roof, as well as material for waterproofing, structural support, and insulation. A new study from Reed College in collaboration with the University of Illinois and Portland State University explores the benefits of green roofs and how much Portland residents are willing to pay to increase the number of green roofs across the city.

“Countries around the world are investing significant public resources to reduce the impact of stormwater runoff,” explains Amy Ando, professor of agricultural and consumer economics at U of I, and a co-author on the study. “Green roofs are part of that solution because they capture some of the rain that would otherwise end up in sewage systems. Knowing the benefits from investing in green roofs is important for implementing sound public policies.”

The study investigates how much people would pay for benefits that include reduced sewer overflow events (CSOs), reduced urban heat island effect, and increased presence of pollinators like bees and butterflies. Like many cities, extreme rainfall events in Portland can quickly overwhelm old sewer systems and lead to flooding, which impacts water quality as well as transportation and properties.

“Although CSO events have declined dramatically in Portland after a major system upgrade ($1.4 billion “Big Pipe Project”), they still happen,” says Noelwah Netusil, professor of economics at Reed College and lead author on the paper. “Our findings show that survey respondents place the largest value on reducing CSO events further and are willing to support additional funding for this.”

Since 2018, the city of Portland has required new buildings in the central city with a footprint over 20,000 square feet to have an ecoroof covering 100% of the area (minus a few exceptions like solar panels and evacuation routes) to further protect the city from flooding. Most green roofs are concentrated in the city center, covering 1.4 million square feet.

Survey respondents indicated how much they would pay for a green roof to result in a scale of benefits. For example, it would cost more to decrease sewer overflows three times per year rather than two, lower the air temperature by over one degree rather than half a degree, and bring in a significant amount of bees, birds, and butterflies rather than keep pollinators at the same level.

For green roofs to reduce average temperatures by more than 1 degree Fahrenheit, reduce sewer overflows by three per year, and increase pollinators by 150%, respondents were willing to pay $442.40 per household. That amounts to $116.8 million for the city of Portland. For green roofs to reduce summer temperatures by less than 0.5 degrees, reduce sewer overflow by one, and increase pollinators by 50%, residents were willing to pay $202.40 per household or $54.4 million total for Portland. The cost would be added in monthly installments to their sewage and stormwater utility bill for one year and green roofs would be installed a year after the program was fully funded. 

While survey respondents who had visited or seen a green roof had the highest estimated willingness to pay to support the program described in the survey, respondents who knew nothing about green roofs prior to taking the survey were still supportive of the green roof program. Furthermore, people generally preferred ecoroofs to be more equally spread out across the city rather than concentrated in the city center.

“Reducing CSO events had the largest value for all survey respondents – whether they had visited, seen, heard, or knew nothing about green roofs prior to taking the survey,” Netusil explains. “The total estimated benefits from the programs we examined would be sufficient to more than double the number of green roofs on commercial and industrial properties in our study area (Portland).”

Eliana Brown, University of Illinois Extension and Illinois-Indiana Sea Grant water quality specialist, says the study’s results will be included on a new green stormwater infrastructure website.

“When municipalities in Illinois contact us because they’re interested in applying green infrastructure, they want to know how the public will benefit from their investment,” Brown states. “This new research on green roofs goes beyond Portland, giving gives stormwater professionals more tools to advocate for practices that are valuable for communities across Illinois and elsewhere.” 

The paper, “Valuing the public benefits of green roofs,” is published in Landscape and Urban Planning [https://doi.org/10.1016/j.landurbplan.2022.104426]. Authors include Noelwah Netusil, Lauren Lavelle, Sahan Dissanayake, and Amy Ando.

The research is funded by the Bernard Goldhammer Grant for Research on Economics and Natural Resources, Reed College and the Stendal Fund for Economics, Reed College. This paper is also based in part on work funded by the USDA-NIFA W4133 Multistate Research Grant 1008843.

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JOURNAL

Landscape and Urban Planning

DOI

10.1016/j.landurbplan.2022.104426 

METHOD OF RESEARCH

Survey

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Valuing the public benefits of green roofs

A Concordia-made tool assessing indoor COVID-19 transmission risks expands across North America

Leon Wang’s web tool CityRPI can help locals determine the risks of airborne infection using customizable assessments based on building type and mitigation measures

Peer-Reviewed Publication

CONCORDIA UNIVERSITY

 

IMAGE: LEON WANG: “WE NEED TO EVALUATE WHICH STRATEGIES ARE MOST EFFECTIVE ON A CASE-BY-CASE, BUILDING-BY-BUILDING BASIS.” view more 

CREDIT: CONCORDIA UNIVERSITY

It is becoming increasingly likely that humanity will have to learn to live with COVID-19. But that does not mean we should be letting our guards down or ignoring the way it spreads throughout the population.

As our understanding of the virus’s transmissibility increases, so too does the range of tools available to mitigate it. Among them is the City Reduced Probability of Infection (CityRPI), a web-based tool developed by Leon Wang. The associate professor of building, civil and environmental engineering at the Gina Cody School of Engineering and Computer Science came up with it alongside his PhD students Ali Katal and Maher Albettar. Originally unveiled in the fall of 2020, CityRPI — pronounced “City-R-Pi”— calculates the probability of COVID-19 infection through aerosol transmission in indoor spaces in Montreal.

In a new paper published in the journal Sustainable Cities and Society, Katal, Wang and Albettar show how their tool can be expanded to project this likelihood in cities across North America. The site’s scope grew as the initial project became better known across Canada and the United States and the initial development team began collaborations with other researchers.

CityRPI relies on technical data such as air exchange rates, ventilation and air filtration conditions provided by local users to determine transmission likelihood. Specific building types such as offices, university buildings or retail stores are added to make results even more customizable. So too are in-place mitigating efforts, for instance the wearing of facemasks, the presence of new air filtration systems, reducing time spent on location, opening windows and more. Data of daily COVID-19 cases is provided in real time.

This, the researchers say, can help health officials and the public compare strategies to curb indoor transmission risks as health restrictions loosen and in-person socialization resumes.

CAPTION

CityRPI screen shot

CREDIT

Leon Wang

Different solutions for different buildings

Besides getting fully vaccinated, the wearing of facemasks is still the single most effective method of cutting down the transmission of COVID-19. But as Wang notes, there is a range of complementary strategies that can also be used to reduce the risk even further – but not all of them are equally effective in all types of buildings.

“As we see on the website, each building is different,” he says. “And so the risks associated with each are different. The effectiveness of different strategies should not be evaluated only in an absolute sense. We need to evaluate which strategies are most effective on a case-by-case, building-by-building basis. An air purifier may be very effective in a classroom, but much less so in a large indoor space like a concert hall.”

Wang does not think CityRPI’s potential ends with buildings. He envisions several other functionalities: one example is developing a method of calculating dynamic mitigation and risk assessment based on an individual’s daily movements, allowing them to identify potential exposure during their daily commute; another is using public data to assess CO2 levels and report ventilation conditions in local schools. It can also be adapted to track other airborne viral transmissions.

“The website can be extended to provide information not only about COVID but also, for example, influenza,” he says. “The methodology is similar. We would be able to provide some guidelines and inputs for those who want to reduce their chances of catching the flu or other airborne diseases.”

This research was supported by the Natural Sciences and Engineering Research Council of Canada and the Advancing Climate Change Science in Canada Program.

Read the cited paper: “A real-time web tool for monitoring and mitigating indoor airborne COVID-19 transmission risks at city scale”

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JOURNAL

Sustainable Cities and Society

DOI

10.1016/j.scs.2022.103810 

METHOD OF RESEARCH

Computational simulation/modeling

SUBJECT OF RESEARCH

People

ARTICLE TITLE

A real-time web tool for monitoring and mitigating indoor airborne COVID-19 transmission risks at city scale

ARTICLE PUBLICATION DATE

3-Mar-2022

COI STATEMENT

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Hidden benefit: Facemasks may reduce severity of COVID-19 and pressure on health systems, researchers find

Peer-Reviewed Publication

MCMASTER UNIVERSITY

 

IMAGE: A NEW MATHEMATICAL MODEL SUGGESTS EFFECTIVE MASKING COULD DRASTICALLY SLOW THE SPREAD OF COVID-19. view more 

CREDIT: MCMASTER UNIVERSITY, HAMILTON, ONTARIO, CANADA

HAMILTON, May 4, 2022 — McMaster University researchers who study the dynamics of infectious disease transmission have investigated the population-level consequences of a potentially significant––and unobvious––benefit of wearing masks.

For the study, the researchers developed a model to investigate COVID-19 “variolation”––an incidental but potentially beneficial form of immunization achieved by inhaling smaller doses of the virus than would be inhaled without a mask.

A form of variolation was deliberately used in the 18th century to control smallpox. It involved infecting a healthy individual with small doses of the live virus taken from a dried scab or pustule of a person infected with smallpox.  Variolated individuals often experienced far less severe disease than those who were infected naturally, but nevertheless were immune to further infection.

Early in the COVID-19 pandemic, it was suggested that people who were infected while masked might experience mild illness and could be considered “variolated”.

The new mathematical model allows researchers to estimate the potential impact of this effect on the population as a whole.

“If the variolation effect is strong, then the number of severe cases, and consequently pressure on health-care systems, could be substantially reduced if most people wear masks –– even if masks don't prevent them from being infected,” says senior author David Earn, Faculty of Science Research Chair in Mathematical Epidemiology and Professor of Mathematics at McMaster and Canada’s Global Nexus for Pandemics & Biological Threats.

The model suggests effective masking could drastically slow the spread of COVID-19, reduce the magnitude of the pandemic peak by “flattening the curve,” and reduce the prevalence of severe cases from that point forward.

“Our qualitative findings are that the value of masking is under-appreciated in a public health context, especially as COVID-19 transitions from pandemic to endemic, and we should think twice about getting rid of mask mandates,” says Zachary Levine, lead author of the study and a former undergraduate in the Arts and Science programme at McMaster. Levine is now a graduate student at the Weizmann Institute of Science in Israel. 

“As we prepare for the next pandemic, understanding how different infection control strategies could affect disease dynamics could help us understand which policies are worth pursuing,” he says.

The results of this research are potentially applicable to any respiratory infection that is transmitted by inhaling infectious particles. For future COVID variants or other infectious diseases, the model can be used to study how increasing the proportion of mild cases affects the overall dynamics of disease spread.

“If wearing a mask protects you in addition to those in the room around you, it could also have significant impacts for everyone who may not be in the room,” says Levine.

The study was published online in the Journal of the Royal Society Interface.

-30-

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JOURNAL

Journal of The Royal Society Interface

ARTICLE PUBLICATION DATE

4-May-2022

NREL calculates lost value of landfilled plastic in US

Peer-Reviewed Publication

DOE/NATIONAL RENEWABLE ENERGY LABORATORY

With mountains of plastic waste piling up in landfills and scientists estimating that there will be more plastics by weight than fish in the ocean by 2050, the growing environmental challenge presented to the world by plastics is well understood. What is less well understood by the scientific community is the lost energy opportunity. In short, plastic waste is also energy wasted.

Scientists at the U.S. Department of Energy’s (DOE’s) National Renewable Energy Laboratory (NREL) calculated the energy value of landfilled plastic waste in 2019 was enough to supply 5% of the power used by the country’s transportation sector, or 5.5% by the industrial sector.

They also provided a look at how much plastic waste has been deposited in landfills, on a regional, state, and county level, and the problem is bigger than previously believed. NREL estimates the amount of plastic waste in the United States is 44 million metric tons. Using a slightly different methodology, the U.S. Environmental Protection Agency puts the figure at 32.2 million metric tons.

“For us to tackle plastic waste pollution, we really need to understand better where those resources are,” said Anelia Milbrandt, a senior research analyst at NREL and co-author of a new paper, “Quantification and evaluation of plastic waste in the United States,” published in the journal Resources, Conservation & Recycling. “We would like to bring awareness to communities about the potential for these materials.”

Her NREL co-authors are Kamyria Coney, Alex Badgett, and Gregg Beckham. A senior research fellow, Beckham heads the BOTTLE Consortium, a collaborative launched last year in an effort to address the waste-plastics problem.

By identifying areas with large quantities of plastic waste, the scientists are hoping to highlight the economic opportunities that could arise by recovering their value through different processes. Only about 5% of the waste plastic in the United States was recycled in 2019, while 86% was left in landfills. The rest was burned to generate electricity.

NREL’s analysis of the discarded plastics examined seven materials—variously used to make bottles, CDs, milk jugs, take-out containers, and bags, among other items. Communities across the country spent about $2.3 billion on plastic waste disposal in 2019.

The researchers noted the amount of landfilled plastic waste in the United States has been increasing because of several factors, including low recycling rates, population growth, consumer preference for single-use plastics, and low disposal fees in certain parts of the country. The problem has been exacerbated by China’s refusal beginning in 2017 to import nonindustrial plastic waste from the United States.

Developing new recycling techniques for plastics would create incentives for a circular economy, where what once was discarded would be reused instead of virgin plastics. The market value of landfilled plastic ranges from $4.5 billion to $9.9 billion, or $7.2 billion on average, the researchers estimated. The embodied energy in the waste plastic—an indicator of how much energy it took to manufacture the materials—equates to about 12% of the country’s energy consumption by the industrial sector.

Some types of plastic are separated and recycled, chiefly polyethylene terephthalate (commonly known as PET), used to make soda bottles; and high-density polyethylene, used for milk jugs and shampoo bottles, but these still represent a significant percentage of plastics found in landfills.

The filmy plastic used for bags is among the most prevalent type found in landfills.

The researchers pointed out two possible solutions for the plastics not being recycled: Develop new products that rely on these plastics to encourage their sorting and collection, and develop advanced sorting technologies that could eventually lead to increased use of recycled materials.

“I'm hoping this paper also increases awareness for industry and investors to look for opportunities,” Milbrandt said.

The amount of plastic waste correlates with population size. California, Texas, and Florida are the three most populous states and also have the largest amount of landfilled plastic waste. New York, however, is fourth for population, but it ships much of its waste outside of the state.

“Plastic waste is not just an environmental issue. It’s a waste management issue. It’s also a land use issue because landfills are closing in many areas,” Milbrandt said. “What do we do with all that waste? It has to go somewhere. I believe local governments and industry developers will see a benefit of this report by providing them information to support decisions.”

DOE’s  Bioenergy Technologies Office funded the research.

NREL is the U.S. Department of Energy's primary national laboratory for renewable energy and energy efficiency research and development. NREL is operated for the Energy Department by the Alliance for Sustainable Energy, LLC.

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JOURNAL

Resources Conservation and Recycling

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Quantification and evaluation of plastic waste in the United States

Studying wealth inequality in animals can reveal clues about how their societies evolved

A new review creates a framework for learning about animal societies by drawing inspiration from studies of inequality in humans.

Peer-Reviewed Publication

MAX-PLANCK-GESELLSCHAFT

 

IMAGE: ACROSS ANIMAL SOCIETIES, SOME INDIVIDUALS BENEFIT MORE FROM GROUP-LIVING, WHEREAS OTHERS ARE LEFT OUT. view more 

CREDIT: LAURA SMALE

Wealth inequality is a research topic typically reserved for humans. Now, research from the Max Planck Institute of Animal Behavior and the University of Nebraska-Lincoln suggests that studying wealth inequality in animals can help shed light on social evolution. Adapting approaches from the study of wealth inequality in humans, the researchers show how wealth—in the form of material goods, individual attributes, or social connections—occurs broadly across animal species and can be distributed equally or unequally. This framework offers the opportunity to unite different corners of evolutionary biology under the umbrella of wealth inequality, exploring the idea that the unequal distribution of value, whatever form that value may take, has important consequences for animal societies.

Inequality is one of the greatest challenges of modern society and plays a prominent role in social and political debate. In the fields of economics and sociology, scholars study inequality in order to understand where it comes from, what are its consequences, and how we might implement policies that produce more productive, healthy, and equitable societies. An insight from this work is that inequality can have potent consequences for those of us living in these societies. 

It was this finding that captured the attention of Eli Strauss, from the Max Planck Institute of Animal Behavior in Germany (MPI-AB), and Daizaburo Shizuka, from University of Nebraska-Lincoln—two behavioral ecologists who study social evolution in non-human societies. “Reading these fascinating sociology and economics papers, it struck me that this work shares a common goal with my work in animal behavior, which is that we both want to understand how inequality arises and affects outcomes for individuals and groups,” says Strauss, first author on the paper and a post-doctoral researcher at MPI-AB.

A new framework in the study of social evolution

It’s not that inequality hadn’t been studied in animals before. Animal researchers have long explored differences among animals in their physical traits, the territory and resources they acquire, the structures they construct, or the social power they wield. However, what was missing was the overarching view that these different dimensions of animals’ lives are linked under the umbrella of inequality. “As we read, we wondered how the scholarship on the causes and consequences of inequality in humans could help biologists like us better understand animal societies,” says Daizaburo Shizuka, an Associate Professor in the School of Biological Sciences at the University of Nebraska-Lincoln.

In a review paper published in Proceedings of the Royal Society B, Strauss and Shizuka gather work from different academic fields to bridge the divide between inequality research in human and animal societies. Their focus was on what might be learned about animals by drawing inspiration from studies of inequality in humans. Their review is among the first studies to unite these different areas of research as a means to understand how the unequal distribution of value—in whatever form it takes—shapes animal societies.

Can animals have “wealth”?

First, however, the researchers had to find common ground across humans and animals. In humans, “inequality” exists when something of value is distributed unequally among individuals. Usually, that value is defined as their wealth.

“Animals don’t have bank accounts, so how can they be wealthy?,” says Strauss. To answer this question, the scientists turned to research in evolutionary anthropology that explores inequality in hunter-gatherer, pastoralist, and other small-scale human societies. “These societies show varying degrees of wealth inequality, but wealth isn’t limited to bills and coins,” he adds. Instead, anthropologists view wealth as more broadly made up of material goods, individual characteristics like knowledge or hunting ability, and social connections. For instance, a woman could be wealthy by owning many cows, being skillful at growing crops, or having influence in her society.  

The review highlights the ways in which these same human dimensions of wealth very clearly operate in animals. Territory ownership and access to food are types of material wealth that are widespread in animals. For instance, squirrels and acorn woodpeckers build food caches and stock them with hordes of nuts and seeds. In dolphins and New Caledonian crows, tool use techniques are valuable chunks of information that open up new foraging opportunities.

Social relationships are also a critical source of wealth in many species, such as in spotted hyenas and ravens, which form alliances with their group-mates that help them rise through the ranks in their societies. Interestingly, like wealth in humans, wealth in animals is sometimes transferred from parents to offspring. Just as money can vary in how unequally it is distributed among people, these types of wealth can be spread fairly evenly among individual animals or can be concentrated in the hands of just a wealthy few.

CAPTION

Figure from the paper demonstrating how wealth inequality (center circle) in animals arises from different types of wealth (top left). This inequality can have consequences for individuals that are independent of wealth (top right), and both behavioral processes and ecological processes can shape the amount of inequality in societies (bottom left). Social mobility, or changes in wealth in individuals and lineages over time, is predicted to impact individual and group traits (bottom right).

CREDIT

Proc B

Shedding light on social evolution

Armed with this broad view of wealth inequality, the authors then explore the ways that inequality research in humans can help us better understand how animal societies work. They discuss theories about what make some societies more unequal than others, the consequences of inequality for individual health and group success, and the ways that individuals and lineages change in wealth over time through social mobility.

Says Shizuka: “The structure of a society has a lot of different influences on all individuals that live within it. In many cases, the differences between individuals arise from the various ways in which unequal societies affect them. In turn, individuals try to exert control over or navigate these unequal systems in different ways. The biology of animal societies includes these types of dynamics, and we can’t understand the evolution of social animals without recognizing this feedback between the individual and the society.”

“Our hope is that this paper will guide future research into wealth inequality across species, which will ultimately lead to a better understanding of the evolution of traits that help animals get the most out of living socially,” adds Strauss.

The authors acknowledge that studying inequality in animals could also shed light on how inequality operates in human societies, but advise that caution is needed when looking to animals to understand ourselves. Humans are a particular animal species with unique social and cognitive traits. While it’s unlikely that inequality operates completely differently in humans than in other animals, there are also no other societies that operate at the scale of the modern human global economy.

“We can look to other species to understand the general evolutionary processes that produce all animals, ourselves included,” says Strauss, “but the question of what makes an ethical human society is fundamentally a moral question where the social lives of animals can’t guide us. This is something we need to figure out on our own.”

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JOURNAL

Proceedings of the Royal Society B Biological Sciences

DOI

10.1098/rspb.2022.0500 

METHOD OF RESEARCH

Meta-analysis

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

The ecology of wealth inequality in animal societies.

ARTICLE PUBLICATION DATE

4-May-2022

Seashell-inspired Sandia shield protects materials in hostile environments

Environmentally friendly coating outperforms conventional materials

Peer-Reviewed Publication

DOE/SANDIA NATIONAL LABORATORIES

 

IMAGE: PHYSICIST CHAD MCCOY AT SANDIA NATIONAL LABORATORIES’ Z MACHINE LOADS SAMPLE COATINGS INTO HOLDERS. WHEN Z FIRES, RESEARCHERS WILL OBSERVE HOW WELL PARTICULAR COATINGS PROTECT OBJECTS STACKED BEHIND THEM. view more 

CREDIT: BRET LATTER, SANDIA NATIONAL LABORATORIES

ALBUQUERQUE, N.M. — Word of an extraordinarily inexpensive material, lightweight enough to protect satellites against debris in the cold of outer space, cohesive enough to strengthen the walls of pressurized vessels experiencing average conditions on Earth and yet heat-resistant enough at 1,500 degrees Celsius or 2,732 degrees Fahrenheit to shield instruments against flying debris, raises the question: what single material could do all this? The answer, found at Sandia National Laboratories, is sweet as sugar.

That’s because it is, in fact, sugar — very thin layers of confectioners’ sugar from the grocers, burnt to a state called carbon black, interspersed between only slightly thicker layers of silica, which is the most common material on Earth, and baked. The result resembles a fine layer cake, or more precisely, the organic and inorganic layering of a seashell, each layer helping the next to contain and mitigate shock.

“A material that can survive a variety of insults — mechanical, shock and X-ray — can be used to withstand harsh environmental conditions,” said Sandia researcher Guangping Xu, who led development of the new coating. “That material has not been readily available. We believe our layered nanocomposite, mimicking the structure of a seashell, is that answer.”

Most significantly, Xu said, “The self-assembled coating is not only lightweight and mechanically strong, but also thermally stable enough to protect instruments in experimental fusion machines against their own generated debris where temperatures may be about 1,500 C. This was the initial focus of the work.”

“And that may be only the beginning,” said consultant Rick Spielman, senior scientist and physics professor at the Laboratory for Laser Energetics at the University of Rochester, credited with leading the initial design of Sandia’s Z machine, one of the destinations for which the new material is intended. “There are probably a hundred uses we haven’t thought of.” He envisions possible electrode applications delaying, rather than blocking, surface electron emissions.
Aiding the nuclear survivability mission

The coating, which can be layered on a variety of substrates without environmental problems, was the subject of a Sandia patent application in June 2021, an invited talk at a pulsed power conference in December 2021 and again in a recent technical article in MRS Advances, of which Xu is lead author.

The work was done in anticipation of the increased shielding that will be needed to protect test objects, diagnostics and drivers inside the more powerful pulsed power machines of the future. Sandia’s pulsed-power Z machine — currently the most powerful producer of X-rays on Earth — and its successors will certainly require still greater debris protection against forces that could compare to numerous sticks of dynamite exploding at close range.
Chad McCoy loads sample coatings at Sandia’s Z machine

Physicist Chad McCoy at Sandia National Laboratories’ Z machine loads sample coatings into holders. When Z fires, researchers will observe how well particular coatings protect objects stacked behind them. (Photo by Bret Latter) Click the thumbnail for a high-resolution image.

“The new shielding should favorably impact our nuclear survivability mission,” said paper author and Sandia physicist Chad McCoy. “Z is the brightest X-ray source in the world, but the amount of X-rays is only a couple percent of the total energy released. The rest is shock and debris. When we try to understand how matter — such as metals and polymers — interacts with X-rays, we want to know if debris is damaging our samples, has changed its microstructure. Right now, we’re at the limit where we can protect sample materials from unwanted insults, but more powerful testing machines will require better shielding, and this new technology may enable appropriate protection.”

Other, less specialized uses remain possibilities.

CAPTION

Mechanical properties of representative high-strength materials versus natural seashell and Sandia National Laboratories-developed coating.

CREDIT

Data provided by Hongyou Fan and Guangping Xu, Sandia National Laboratories

The inexpensive, environmentally friendly shield is light enough to ride into space as a protective layer on satellites because comparatively little material is needed to achieve the same resilience as heavier but less effective shielding currently in use to protect against collisions with space junk. “Satellites in space get hit constantly by debris moving at a few kilometers per second, the same velocity as debris from Z,” McCoy said. “With this coating, we can make the debris shield thinner, decreasing weight.”

Thicker shield coatings are durable enough to strengthen the walls of pressurized vessels when added ounces are not an issue.
Dramatic cost reduction anticipated

According to Guangping, the material cost to fabricate a 2-inch diameter coating of the new protective material, 45 millionths of a meter and microns thick, is only 25 cents. In contrast, a beryllium wafer — the closest match to the thermal and mechanical properties of the new coating, and in use at Sandia’s Z machine and other fusion locations as protective shields — costs $700 at recent market prices for a 1-inch square, 23-micron-thick wafer, which is 3,800 times more expensive than the new film of same area and thickness.

Both coatings can survive temperatures well above 1,000 C, but a further consideration is that the new coating is environmentally friendly. Only ethanol is added to facilitate the coating process. Beryllium creates toxic conditions, and its environs must be cleansed of the hazard after its use.
How testing proceeded

The principle of alternating organic and inorganic layers, a major factor in seashell longevity, is key to strengthening the Sandia coating. The organic sugar layers burnt to carbon black act like a caulk, said Sandia manager and paper author Hongyou Fan. They also stop cracks from spreading through the inorganic silica structure and provide layers of cushioning to increase its mechanical strength, as was reported 20 years ago in an earlier Sandia attempt to mimic the seashell mode.

Greg Frye-Mason, Sandia campaign manager for the Assured Survivability and Agility with Pulsed Power, or ASAP, Laboratory Directed Research and Development mission campaign funding the research, initially had his doubts about the carbon insertion.

“I thought that the organic layers would limit applicability since most degrade by 400 to 500 C,” he said.

But when the carbon-black concept demonstrated robustness to well over 1,000 C, the positive result overcame the largest risk Frye-Mason saw as facing the project.

Seashell-like coatings initially tested at Sandia varied between a few to 13 layers. These alternating materials were pressed against each other after being heated in pairs, so their surfaces crosslinked. Tests showed that such interwoven nanocomposite layers of silica with the burnt sugar, known as carbon black after pyrolysis, are 80% stronger than silica itself and thermally stable to an estimated 1,650 C. Later sintering efforts showed that layers, self-assembled through a spin-coating process, could be batch-baked and their individual surfaces still crosslinked satisfactorily, removing the tediousness of baking each layer. The more efficient process achieved very nearly the same mechanical strength.

Data table Mechanical properties of representative high-strength materials versus natural seashell and Sandia National Laboratories-developed coating. (Graphic by Alicia Bustillos and data provided by Hongyou Fan and Guangping Xu)

Research into the coating was funded by ASAP to develop methods to protect diagnostics and test samples on Z and on next-generation pulsed power machines from flying debris.

“This coating qualifies,” Frye-Mason said.

Sandia National Laboratories is a multimission laboratory operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration. Sandia Labs has major research and development responsibilities in nuclear deterrence, global security, defense, energy technologies and economic competitiveness, with main facilities in Albuquerque, New Mexico, and Livermore, California.

CAPTION

Sandia National Laboratories researcher Guangping Xu employs a digital optical microscope to examine the unusually hard coatings his lab has produced. The aim is better, cheaper protection of instruments and drivers in danger of fast-moving debris flung by Sandia’s Z machine when it fires. The coatings offer many other possibilities as well.

CREDIT

Bret Latter, Sandia National Laboratories

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JOURNAL

MRS Advances

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Bioinspired synthesis of thermally stable and mechanically strong nanocomposite coatings

Efforts to take fake news and misinformation in Africa must take account of the continent’s unique “pavement media”, study shows

Peer-Reviewed Publication

UNIVERSITY OF EXETER

The spread of fake news through “pavement media” in Africa means the continent needs unique techniques to tackle the spread of misinformation, a new study says.

Discussions about current affairs in marketplaces, places of worship, bars, and other social spaces, and through songs, sermons, and graffiti form a key part of the media ecosystem in Africa.

This – combined with traditional media – means information from social media quickly crosses into offline spaces. New research carried out in Ghana says this means efforts intended to combat the spread of misinformation need to move beyond Western-centred conception of what constitutes “media” and take different local modalities of media access and fact-checking into account.

The study, in the journal African Affairs, says social, traditional and pavement media are all used to spread fake news and misinformation in the country. Those using social media are usually able to independently assess the accuracy of information they read. They are keenly aware of the prevalence of misinformation on social media and generally more suspicious of social media content.

Those who hear about misinformation on social media second-hand, or via pavement radio are less likely to question it, leaving them more vulnerable. They usually hear about this information from people they trust, and through existing social hierarchies, so are more likely to take it at face value.

The study was carried out by Professor Elena Gadjanova from the University of Exeter, Professor Gabrielle Lynch from the University of Warwick and Dr Ghadafi Saibu from the Bayreuth International Graduate School of African Studies.

Dr Gadjanova said: “Africa’s interconnected media spaces and multiple, intersecting, digital inequalities, have significant implications for citizens’ patterns of exposure, relative vulnerability, and response to social media misinformation.

“The interconnected media space means that misinformation originating on social media travels through multiple channels simultaneously, significantly increasing its reach. Efforts to battle misinformation should take this into account. There is a need to harness multiple information channels to debunk misinformation: local and national media, common information diffusion spaces, such as markets and high-status individuals who enjoy high levels of trust locally.”

The study says social media literacy campaigns are unlikely to be effective unless they have influence in wider society. Beyond encouraging fact-checking on an individual level, governments and civil society should strive to normalize it as social practice, which would empower indirect social media users to exercise more agency in responding to suspected misinformation.

In Africa social media, and the mobile phones that it is usually accessed through, have become a part of everyday life. The study describes the social divide between the highly literate and well off, and those with low literacy skills; between citizens with unlimited access and those with limited opportunities to browse online and those who are offline, but have access to newspapers, TV, and informed social networks, and those who are offline, but have limited access to traditional media and whose friends and family members are similarly disengaged.

 

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JOURNAL

African Affairs

DOI

10.1093/afraf/adac009 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Misinformation across digital divides: Theory and evidence from Northern Ghana

ARTICLE PUBLICATION DATE

29-Apr-2022