USA As teens delay driver licensing, they miss key safety instruction

YALE UNIVERSITY

 

New Haven, Conn. -- Teens are getting licensed to drive later than they used to and missing critical safety training as a result, according to Yale researchers.

In a study in the July 2 edition of the Journal of Adolescent Health, researchers at Yale identified some of the factors contributing to delaying driving licensure, or DDL, and pointed to policy changes that could expand safety training regardless of age.

When teens delay getting their driver's licenses, said lead author Dr. Federico E. Vaca, professor of emergency medicine and director of the Yale Developmental Neurocognitive Driving Simulation Research Center (DrivSim Lab), they age out of these safety measures which are not required after a person turns 18. "On the day I turned 16, I was at the DMV getting my license," said Vaca. "Now, that's not happening. We wanted to know, why not?"

The study found that race, socioeconomic status, and parenting are all important factors.

From 2006 to 2016, the proportion of high school seniors with driver's licenses fell from 81% to 72%, and at least 70% of eligible adolescents delay licensing by at least one year, the study noted. These delays affect the extent to which these young drivers participate a program known as Graduated Driver Licensing (GDL), requirements that young drivers must meet before they have a fully independent license. The GDL program, some version of which exists in all 50 states, typically requires 16-year-olds to log a certain number of hours of practice driving with a parent or guardian during a learner's permit stage, and later restricts late-night driving and driving with young passengers. Many states also include restrictions on cell phone use in the car as part of the GDL.

"These are key restrictions," said Vaca. "All the epidemiology shows that the later you drive at night, the more dangerous it is. "Once you get past 9 or 10 p.m., the fatal crash rate goes up. We also know from the literature that, for young drivers, the risk of fatal crashes also goes up with the number of passengers in the car."

GDL addresses these facts, and the programs have been successful in promoting safer driving, Vaca said. After GDL programs were introduced in the U.S. in the mid-nineties, fatal crashes among teens declined by 74% among 16-year-olds, by 61% among 17-year-olds, by 55% among 18-year-olds, and by 45% among 19-year-olds.

The researchers found that certain racial, ethnic, and socioeconomic groups are delaying licensure at higher rates -- in particular Latino and black teens. Using data from the National Institutes of Health's NEXT Generation Health Study, which followed a cohort of 10th grade students into adulthood, the Yale researchers found that Latino teens were 4.5 times as likely as white teens to delay getting their licenses by over two years and black teens were 2.3 times as likely.

Furthermore, they found that teens whose parents' highest educational degree level was high school were 3.7 times more likely to delay by over two years than those whose parents had a college degree. Teens from poor families were 4.4 times as likely to delay for more than two years compared to those from affluent families. Teens who perceived that their mothers were actively involved in their lives and monitoring their behaviors were less likely to delay their driving licensure. A similar effect was not seen with fathers.

When young people don't start driving until their early 20s, said Vaca, they are navigating a much more complicated world, where exposure to alcohol and drugs -- a major contributor to crash risk -- is considerably higher than for teens.

"If you haven't gone through GDL, you're not gradually exposed to nighttime driving and typically not gradually exposed to driving with several passengers where you progressively learn to manage the occupant space while driving," Vaca said.

Vaca said that in addition to missing safety instruction, which results in more crashes and fatalities among vulnerable populations, some teens who delay licensure miss out on employment, education, and other opportunities.

One solution, Vaca said, can be found by looking to GDL policies in other countries, such as Australia and the United Kingdom, where GDL restrictions are applied to novice drivers of all ages before a full license is issued.

"Motor vehicle crashes are the leading cause of death for young people," Vaca said. "It's important that they get sufficient supervised practice driving as well as gradual exposure to a variety of driving conditions and learn how to safely navigate them."

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Insufficient sleep harms children's mental health

University of Houston study: Poor sleep at night 'spills over' into children's emotional lives

UNIVERSITY OF HOUSTON

IMAGE: POOR SLEEP HARMS CHILDREN'S MENTAL HEALTH AND EMOTIONAL STABILITY ACCORDING TO A NEW STUDY PUBLISHED BY UNIVERSITY OF HOUSTON PROFESSOR OF PSYCHOLOGY AND DIRECTOR OF THE SLEEP AND ANXIETY CENTER... view more 

CREDIT: UNIVERSITY OF HOUSTON

In a new study published in the Journal of Child Psychology and Psychiatry, Candice Alfano, University of Houston professor of psychology and director of the Sleep and Anxiety Center of Houston, reports the results from an innovative, experimental study showing inadequate nighttime sleep alters several aspects of children's emotional health.

Although plenty of correlational research links inadequate sleep with poor emotional health, experimental studies in children are rare. Alfano and her team studied 53 children ages 7-11 over more than a week. The children completed an in-lab emotional assessment twice, once after a night of healthy sleep and again after two nights where their sleep was restricted by several hours.

"After sleep restriction, we observed changes in the way children experience, regulate and express their emotions," reports Alfano. "But, somewhat to our surprise, the most significant alterations were found in response to positive rather than negative emotional stimuli."

The multi-method assessment had children view a range of pictures and movie clips eliciting both positive and negative emotions while the researchers recorded how children responded on multiple levels. In addition to subjective ratings of emotion, researchers collected respiratory sinus arrhythmias (a non-invasive index of cardiac-linked emotion regulation) and objective facial expressions. Alfano points out the novelty of these data. "Studies based on subjective reports of emotion are critically important, but they don't tell us much about the specific mechanisms through which insufficient sleep elevates children's psychiatric risk."

Alfano highlights the implications of her findings for understanding how poor sleep might "spill over" into children's everyday social and emotional lives. "The experience and expression of positive emotions are essential for children's friendships, healthy social interactions and effective coping. Our findings might explain why children who sleep less on average have more peer-related problems," she said.

Another important finding from the study is that the impact of sleep loss on emotion was not uniform across all children. Specifically, children with greater pre-existing anxiety symptoms showed the most dramatic alterations in emotional responding after sleep restriction.

According to Alfano, these results emphasize a potential need to assess and prioritize healthy sleep habits in emotionally vulnerable children.

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Breakthrough machine learning approach quickly produces higher-resolution climate data

DOE/NATIONAL RENEWABLE ENERGY LABORATORY

 Researchers at the U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL) have developed a novel machine learning approach to quickly enhance the resolution of wind velocity data by 50 times and solar irradiance data by 25 times--an enhancement that has never been achieved before with climate data.

The researchers took an alternative approach by using adversarial training, in which the model produces physically realistic details by observing entire fields at a time, providing high-resolution climate data at a much faster rate. This approach will enable scientists to complete renewable energy studies in future climate scenarios faster and with more accuracy.

"To be able to enhance the spatial and temporal resolution of climate forecasts hugely impacts not only energy planning, but agriculture, transportation, and so much more," said Ryan King, a senior computational scientist at NREL who specializes in physics-informed deep learning.

King and NREL colleagues Karen Stengel, Andrew Glaws, and Dylan Hettinger authored a new article detailing their approach, titled "Adversarial super-resolution of climatological wind and solar data," which appears in the journal Proceedings of the National Academy of Sciences of the United States of America.

Accurate, high-resolution climate forecasts are important for predicting variations in wind, clouds, rain, and sea currents that fuel renewable energies. Short-term forecasts drive operational decision-making; medium-term weather forecasts guide scheduling and resource allocations; and long-term climate forecasts inform infrastructure planning and policymaking.

However, it is very difficult to preserve temporal and spatial quality in climate forecasts, according to King. The lack of high-resolution data for different scenarios has been a major challenge in energy resilience planning. Various machine learning techniques have emerged to enhance the coarse data through super resolution--the classic imaging process of sharpening a fuzzy image by adding pixels. But until now, no one had used adversarial training to super-resolve climate data.

"Adversarial training is the key to this breakthrough," said Glaws, an NREL postdoc who specializes in machine learning.

Adversarial training is a way of improving the performance of neural networks by having them compete with one another to generate new, more realistic data. The NREL researchers trained two types of neural networks in the model--one to recognize physical characteristics of high-resolution solar irradiance and wind velocity data and another to insert those characteristics into the coarse data. Over time, the networks produce more realistic data and improve at distinguishing between real and fake inputs. The NREL researchers were able to add 2,500 pixels for every original pixel.

"By using adversarial training--as opposed to the traditional numerical approach to climate forecasts, which can involve solving many physics equations--it saves computing time, data storage costs, and makes high-resolution climate data more accessible," said Stengel, an NREL graduate intern who specializes in machine learning.

This approach can be applied to a wide range of climate scenarios from regional to global scales, changing the paradigm for climate model forecasting.

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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Texas hurricanes: Fast like Ike or slow like Harvey?

Climate change will make fast-moving storms more likely in late 21st-century Texas
HOUSTON -- (July 7, 2020) -- Climate change will intensify winds that steer hurricanes north over Texas in the final 25 years of this century, increasing the odds for fast-moving storms like 2008's Ike compared with slow-movers like 2017's Harvey, according to new research.


The study published online July 3 in Nature Communications examined regional atmospheric wind patterns that are likely to exist over Texas from 2075-2100 as Earth's climate changes due to increased greenhouse emissions.

The research began in Houston as Harvey deluged the city with 30-40 inches of rain over five days. Rice University researchers riding out the storm began collaborating with colleagues from Columbia University's Lamont-Doherty Earth Observatory (LDEO) and Harvard University to explore whether climate change would increase the likelihood of slow-moving rainmakers like Harvey.

"We find that the probability of having strong northward steering winds will increase with climate change, meaning hurricanes over Texas will be more likely to move like Ike than Harvey," said study lead author Pedram Hassanzadeh of Rice.

Harvey caused an estimated $125 billion in damage, matching 2005's Katrina as the costliest hurricane in U.S. history. Ike was marked by coastal flooding and high winds that caused $38 billion damage across several states. It was the second-costliest U.S. hurricane at the time and has since moved to sixth. Ike struck Galveston around 2 a.m. Sept. 13, 2008, crossed Texas in less than one day and caused record power outages from Arkansas to Ohio on Sept. 14.

Hassanzadeh, a fluid dynamicist, atmospheric modeler and assistant professor of both mechanical engineering and Earth, environmental and planetary sciences, said the findings don't suggest that slow-moving storms like Harvey won't happen in late 21st century. Rather, they suggest that storms during the period will be more likely to be fast-moving than slow-moving. The study found the chances that a Texas hurricane will be fast-moving as opposed to slow-moving will rise by about 50% in the last quarter of the 21st century compared with the final quarter of the 20th century.

"These results are very interesting, given that a previous study that considered the Atlantic basin as a whole noticed a trend for slower-moving storms in the past 30 years," said study co-author Suzana Camargo, LDEO's Marie Tharp Lamont Research Professor. "By contrast, our study focused on changes at the end of the 21st century and shows that we need to consider much smaller regional scales, as their trends might differ from the average across much larger regions."

Hassanzadeh said the researchers used more than a dozen different computer models to produce several hundred simulations and found that "all of them agreed on an increase in northward steering winds over Texas."

Steering winds are strong currents in the lower 10 kilometers of the atmosphere that move hurricanes.

"It doesn't happen a lot, in studying the climate system, that you get such a robust regional signal in wind patterns," he said.

Harvey was the first hurricane Hassanzadeh experienced. He'd moved to Houston the previous year and was stunned by the slow-motion destruction that played out as bayous, creeks and rivers in and around the city topped their banks.

"I was sitting at home watching, just looking at the rain when (study co-author) Laurence (Yeung) emailed a bunch of us, asking 'What's going on? Why is this thing not moving?'" Hassanzadeh recalled. "That got things going. People started replying. That's the good thing about being surrounded by smart people. Laurence got us started, and things took off."

Yeung, an atmospheric chemist, Hassanzadeh and two other Rice professors on the original email, atmospheric scientist Dan Cohan and flooding expert Phil Bedient, won one of the first grants from Rice's Houston Engagement and Recovery Effort (HERE), a research fund Rice established in response to Harvey.

"Without that, we couldn't have done this work," Hassanzadeh said. The HERE grant allowed Rice co-author Ebrahim Nabizadeh, a graduate student in mechanical engineering, to work for several months, analyzing the first of hundreds of computer simulations based on large-scale climate models.

The day Harvey made landfall, Hassanzadeh also had reached out to Columbia's Chia-Ying Lee, an expert in both tropical storms and climate downscaling, procedures that use known information at large scales to make projections at local scales. Lee and Camargo used information from the large-scale simulations to make a regional model that simulated storms' tracks over Texas in a warming climate.

"One challenge of studying the impact of climate change on hurricanes at a regional level is the lack of data," said Lee, a Lamont Assistant Research Professor at LDEO. "At Columbia University, we have developed a downscaling model that uses physics-based statistics to connect large-scale atmospheric conditions to the formation, movement and intensity of hurricanes. The model's physical basis allowed us to account for the impact of climate change, and its statistical features allowed us to simulate a sufficient number of Texas storms."

Hassanzadeh said, "Once we found that robust signal, where all the models agreed, we thought, 'There should be a robust mechanism that's causing this.'"

He reached out to tropical climate dynamicist Ding Ma of Harvard to get another perspective.

"We were able to show that changes in two important processes were joining forces and resulting in the strong signal from the models," said Ma, a postdoctoral researcher in Earth and planetary sciences.

One of the processes was the Atlantic subtropical high, or Bermuda high, a semipermanent area of high pressure that forms over the Atlantic Ocean during the summer, and the other was the North American monsoon, an uptick in rainfall and thunderstorms over the southwestern U.S. and northwestern Mexico that typically occurs between July and September. Hassanzadeh said recent studies have shown that each of these are projected to change as Earth's climate warms.

"The subtropical high is a clockwise circulation to the east that is projected to intensify and shift westward, producing more northward winds over Texas," he said. "The North American monsoon, to the west, produces a clockwise circulation high in the troposphere. That circulation is expected to weaken, resulting in increased, high-level northward winds over Texas."

Hassanzadeh said the increased northward winds from both east and west "gives you a strong reinforcing effect over the whole troposphere, up to about 10 kilometers, over Texas. This has important implications for the movement of future Texas hurricanes."

Models showed that the effect extended into western Louisiana, but the picture became murkier as the researchers looked further east, he said.

"You don't have the robust signal like you do over Texas," Hassanzadeh said. "If you look at Florida, for instance, there's a lot of variation in the models. This shows how important it is to conduct studies that focus on climate impacts in specific regions. If we had looked at all of North America, for example, and tried to average over the whole region, we would have missed this localized mechanism over Texas."

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Bedient is the Herman Brown Professor of Engineering and department chair of civil and environmental engineering and director of Rice's Severe Storm Prediction, Education and Evacuation from Disasters Center. Cohan is an associate professor of civil and environmental engineering. Yeung is the Maurice Ewing Career Development Assistant Professor in Earth Systems Science in the Department of Earth, Environmental and Planetary Sciences.

The research was supported by the National Science Foundation (AGS-1921413), NASA (80NSSC17K0266), the Gulf Research Program of the National Academies of Sciences, Engineering and Medicine's Early-Career Research Fellowship Program, Rice's Houston Engagement and Recovery Effort Fund, Columbia's Center for Climate and Life Fellows Program, the National Oceanic and Atmospheric Administration (NA16OAR4310079, NA18OAR4310277) and the New York State Energy Research and Development Authority (NYSERDA 103862). Computational resources were provided by the National Science Foundation's Extreme Science and Engineering Discovery Environment (ATM170020), the National Center for Atmospheric Research's Computational and Information Systems Lab (URIC0004) and Rice's Center for Research Computing.

Links and resources:

The DOI of the Nature Communications paper is: 10.1038/s41467-020-17130-7

A copy of the paper is available at: https://doi.org/10.1038/s41467-020-17130-7

High-resolution IMAGES are available for download at:

https://news-network.rice.edu/news/files/2020/07/0703_TEXASSTORMS-harveyISS-lg.jpg

CAPTION: Hurricane Harvey as seen from the International Space Station on Aug. 28, 2017. (Photo courtesy of Randy Bresnik/NASA)

https://news-network.rice.edu/news/files/2020/07/0703_TEXASSTORMS-IkeRain-med.jpg

CAPTION: Map depicting total rainfall from 2008's Hurricane Ike. (Image by Hal Pierce/SSAI/NASA)

https://news-network.rice.edu/news/files/2020/07/0703_TEXASSTORMS-harveyrain-lg.jpg

CAPTION: Map depicting total rainfall from 2017's Hurricane Harvey. (Image courtesy of NOAA)

https://news-network.rice.edu/news/files/2020/07/0703_TEXASSTORMS-pedram-lg.jpg

CAPTION: Pedram Hassanzadeh

This release can be found online at news.rice.edu.

Follow Rice News and Media Relations via Twitter @RiceUNews.

Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,962 undergraduates and 3,027 graduate students, Rice's undergraduate student-to-faculty ratio is just under 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for lots of race/class interaction and No. 4 for quality of life by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger's Personal Finance.

Early childhood education centers can boost parents' engagement at home

UNIVERSITY OF ARIZONA

 

COVID-19 has temporarily shuttered many early childhood education centers across the country, shifting full-time child care and teaching responsibilities largely to parents.

As some of those centers look toward reopening, they can play an important part in ensuring that parents continue to be engaged in their children's education at home, says University of Arizona researcher Melissa Barnett.

In a study conducted before the pandemic began, Barnett and her colleagues looked at the role that early childhood education centers play in encouraging parents to engage in educational activities with their children both at the centers and at home. The researchers also explored how parental engagement can help better prepare young children for kindergarten.

Their findings were recently published in Early Childhood Research Quarterly.

"There's been some research evidence that when parents of preschoolers are more engaged in early childhood education centers, their children may be more prepared for kindergarten. But it's not entirely clear why that's the case," said Barnett, lead study author and an associate professor of family studies and human development in the UArizona Norton School of Family and Consumer Sciences, housed in the College of Agriculture and Life Sciences.

"One of the goals of our study was to understand the extent to which parents perceive that early childhood educators are working with them and engaging them, and whether that is linked to school readiness," said Barnett, who also is director of the Norton School's Frances McClelland Institute for Children, Youth and Families.

Among the researchers' key findings:

When parents perceive that early childhood education centers do a good job of communicating with them and providing information about how their children are doing, they are more likely to engage in educational activities such as reading and singing with their children - both at the center and at home. And the more parents engage in educational activities at home, the better prepared their children are for kindergarten, in terms of language and early reading skills.

The more involved parents are in center activities - such as volunteering in classrooms, attending meetings or chaperoning field trips - the more educational activities they do with their children at home.

Although early childhood education centers appear to influence the quantity of at-home educational activities, they do not influence the quality of those activities. And the quality of at-home educational activities is one of the strongest predictors of a child's school readiness, influencing not only language and early reading skills but also early math skills.

The research is based on data from the Early Childhood Longitudinal Study - Birth Cohort, a nationally representative sample of 10,700 children who were born in the United States in 2001 were followed from birth to kindergarten. The researchers homed in on the 17% of those children who were enrolled in early childhood education centers at age 4.

Those children's parents rated a series of statements designed to measure how well they thought their early childhood education centers did at keeping them informed and involved. The parents also answered questions about how often they engaged in educational activities with their children, both at the center and at home.

The children completed assessments to measure their language, reading and early math skills prior to entering kindergarten.

"For children who are enrolled in early childhood education centers, what parents did at home was a good predictor of how well children were prepared for school, in terms of the quantity of what parents were doing and the quality of what they were doing," Barnett said. "We found that more engagement in the early childhood education centers was related to doing more at home, and that seemed to be especially true for lower-income households."

The researchers also observed parents and children engaging in learning activities and assessed the quality of those interactions based on how much cognitive stimulation they provided. They found that quality matters even more than quantity for school readiness.

"It's important that parents read with their kids and sing to their kids. But the quality of what parents are doing also is really critical and perhaps harder to change," Barnett said.

That's an area where early childhood education centers could make a difference in the future, she said.

"Parents who are able to engage and volunteer at those centers are getting the message that they need to read with their kids and sing songs with their kids, but they may not be getting messages about how best to do that," Barnett said.

Some best practices, she said, include thinking about ways to build activities around a child's unique interests and abilities, and making activities such as reading more meaningful by stopping to ask questions that help children relate stories to their own experiences.

Pandemic Could Impact Access

Unfortunately, Barnett said, many families don't have access to early childhood education centers and the support they provide, especially in lower-income areas, where, according to her findings, they might have the most impact. The problem could be made even worse by COVID-19, she said, as some centers hit hard financially may be forced to close permanently.

"We know that many families in many communities didn't have access to high-quality early childhood education, even before the pandemic, and it's become an increasingly significant problem as centers have closed and may need to remain closed," she said. "In part, our findings point to the value of those opportunities for lower-income parents to be involved in early childhood education centers, so this potentially could even further increase what we see as a socioeconomic gap in school readiness."

For now, with many parents of all socioeconomic backgrounds at home with their kids, Barnett stresses the importance of focusing on quality activities as much as possible.

"This may be an especially challenging time to do that, as parents are juggling multiple potential stressors and time crunches," she said, "but those home learning activities really are important to prepare children for school."

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The complex relationship between deforestation and diet diversity in the Amazon

As increasing areas of the Amazonian rainforest are converted into agricultural land, scientists are examining how this is linked with local communities' food access

INTERNATIONAL CENTER FOR TROPICAL AGRICULTURE (CIAT)

 

IMAGE: COMMERCIAL AGRICULTURE, SUCH AS PALM OIL AND COCOA PLANTATIONS, IS EXPANDING ALONG THE AMAZONIAN FOREST FRONTIER. view more 

CREDIT: © CIAT

Ten years ago, non-indigenous households from three communities in the Ucayali region in Peru regularly ate fish, wild fruits and other products collected from the Amazon forest. Combined with whatever they grew and harvested on their lands, this contributed to a relatively diverse diet. Today, the same households have changed their production strategy and how they get food on the table. Agricultural production, complemented by hunter-gatherer activities, aimed to satisfy both household consumption and income generation. However, this has been largely replaced by commercial agriculture such as palm oil and cocoa. This shift in agricultural production objectives has affected the sources of food for local communities and appears to be associated with relatively less diverse diets, according to a new study authored, among others, by CIAT (now the Alliance of Bioversity International and CIAT) scientists.

"Our objective was to test the hypothesis that the economic transformations linked to the expansion of cash crops in mestizo communities, especially oil palm, were associated with deforestation and reduced agricultural biodiversity and that this was likely to be associated with changes in food access," says Genowefa Blundo Canto, co-author and Post Doc researcher at CIAT at the time of the study.

The study represents one of rather few attempts to trace changes in food access, livelihood strategies, deforestation and agricultural biodiversity over time. The scientists collected data on livelihood strategies and nutritional health among 53 families in the Ucayali region in Peru and compared the results with data gathered from the same families in the early 2000s. Despite the small sample, caused by significant outmigration from these communities, the results were remarkable.

"We found that in the 15-year study period, farming households shifted from diets based on limited consumption of meat and dairy items and high consumption of plant-based foods from their own production, towards diets with high protein and fat content, with food items increasingly purchased in the market. In parallel, production systems became less diversified, more market-orientated and specialised toward commercial crops, oil palm and cacao in particular," says Blundo Canto.

The scientific team concluded that the expansion of commercial agriculture, such as palm oil and cocoa plantations at the Amazonian forest frontier, appears to be associated with simplified food production systems, reduced agricultural diversity and less access to food, measured in terms of the household dietary diversity score.

"This study is crucial to understand how deforestation not only affects the climate, but also has profound socio-economic and nutritional impacts on the communities living on the forest frontier. Even though Peru and other Latin American countries have progressed in economic terms, there are high malnutrition percentages especially among children. Something tells us that even though farmers might now make more money from, for example, oil palm farming, this might not improve other life quality aspects such as nutrition for children," explains another co-author Marcela Quintero, Multifunctional Landscapes Research Area Director at the Alliance.

The marked rise in obesity in rural areas of Peru reflects a worldwide trend. While the study only looked at the diversity of household diets and not the nutritional value, the increased consumption of foods high in saturated fats and ultra-processed foods demands the attention of local policy makers.

"These results, which are consistent with emerging evidence for a dietary transition in the Amazon, have major implications for land use and food policies in the region as well as for health policies, since it has recently been highlighted that unhealthy diets are the main cause of disease worldwide. We therefore recommend that future development actions at the Amazonian forest-agriculture interface should address deforestation and promote agrobiodiversity for more diverse diets and local markets over the expansion of cash crops, in order to ensure long-term food and nutritional security among farmers and the rural communities that they supply," concludes Blundo Canto.

The research team wants to complement the research with a specific study on how the nutritional quality of the diets might have changed to further argue for focused research and policy development that will work for the benefit and well-being of communities living on the borders of forests around the world. Likewise, the team is seeking opportunities to replicate this study with indigenous communities. Meanwhile, the Alliance is working with oil palm producers and the regional government of Ucayali to re-design their business models in a way that are deforestation-free.

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Boron nitride destroys PFAS 'forever' chemicals PFOA, GenX

Pollutant-destroying properties surprise Rice engineer: 'It's not supposed to work'

RICE UNIVERSITY

 

IMAGE: AN ILLUSTRATION OF THE BORON NITRIDE PHOTOCATALYSIS THAT DESTROYS THE POLLUTANT PFOA IN WATER. view more 

CREDIT: IMAGE COURTESY OF M. WONG/RICE UNIVERSITY

HOUSTON -- (July 7, 2020) -- Rice University chemical engineers found an efficient catalyst for destroying PFAS "forever" chemicals where they least expected.

"It was the control," said Rice Professor Michael Wong, referring to the part of a scientific experiment where researchers don't expect surprises. The control group is the yardstick of experimental science, the baseline by which variables are measured.

"We haven't yet tested this at a full scale, but in our benchtop tests in the lab, we could get rid of 99% of PFOA in four hours," Wong said of boron nitride, the light-activated catalyst he and his students stumbled upon and spent more than a year testing.

Their study, which is available online in the American Chemical Society journal Environmental Science and Technology Letters, found boron nitride destroyed PFOA (perfluorooctanoic acid) at a faster clip than any previously reported photocatalyst. PFOA is one of the most prevalent PFAS (perfluoroalkyl and polyfluoroalkyl substances), a family of more than 4,000 compounds developed in the 20th century to make coatings for waterproof clothing, food packaging, nonstick pans and countless other uses. PFAS have been dubbed forever chemicals for their tendency to linger in the environment, and scientists have found them in the blood of virtually all Americans, including newborns.

Catalysts are Wong's specialty. They are compounds that bring about chemical reactions without taking part or being consumed in those reactions. His lab has created catalysts for destroying a number of pollutants, including TCE and nitrates, and he said he tasked his team with finding new catalysts to address PFAS about 18 months ago.

"We tried a lot of things," said Wong, chair of the Department of Chemical and Biomolecular Engineering in Rice's Brown School of Engineering. "We tried several materials that I thought were going to work. None of them did. This wasn't supposed to work, and it did."

The catalyst, boron nitride powder, or BN, is a commercially available synthetic mineral that's widely used in makeup, skin care products, thermal pastes that cool computer chips and other consumer and industrial products.

The discovery began with dozens of failed experiments on more likely PFAS catalysts. Wong said he asked two members of his lab, visiting graduate student Lijie Duan of China's Tsinghua University and Rice graduate student Bo Wang, to do final experiments on one set of candidate compounds before moving on to others.

"There was literature that suggested one of them might be a photocatalyst, meaning it would be activated by light of a particular wavelength," Wong said. "We don't use light very often in our group, but I said, 'Let's go ahead and doodle around with it.' The sun is free energy. Let's see what we can do with light."

As before, none of the experimental groups performed well, but Duan noticed something unusual with the boron nitride control. She and Wang repeated the experiments numerous times to rule out unexpected errors, problems with sample preparation and other explanations for the strange result. They kept seeing the same thing.

"Here's the observation," Wong said. "You take a flask of water that contains some PFOA, you throw in your BN powder, and you seal it up. That's it. You don't need to add any hydrogen or purge it with oxygen. It's just the air we breathe, the contaminated water and the BN powder. You expose that to ultraviolet light, specifically to UV-C light with a wavelength of 254 nanometers, come back in four hours, and 99% of the PFOA has been transformed into fluoride, carbon dioxide and hydrogen."

The problem was the light. The 254-nanometer wavelength, which is commonly used in germicidal lamps, is too small to activate the bandgap in boron nitride. While that was unquestionably true, the experiments suggested it could not be.

"If you take away the light, you don't get catalysis," Wong said. "If you leave out the BN powder and only use the light, you don't get a reaction."

So boron nitride was clearly absorbing the light and catalyzing a reaction that destroyed PFOA, despite that fact that it should have been optically impossible for boron nitride to absorb 254-nanometer UV-C light.

"It's not supposed to work," Wong said. "That's why no one ever thought to look for this, and that's why it took so long for us to publish the results. We needed some sort of explanation for this contradiction."

Wong said he, Duan, Wang and co-authors offered a plausible explanation in the study.

"We concluded that our material does absorb the 254-nanometer light, and it's because of atomic defects in our powder," he said. "The defects change the bandgap. They shrink it enough for the powder to absorb just enough light to create the reactive oxidizing species that chew up the PFOA."

Wong said more experimental evidence will be needed to confirm the explanation. But in light of the results with PFOA, he wondered if the boron nitride catalyst might also work on other PFAS compounds.

"So I asked my students to do one more thing," Wong said. "I had them replace PFOA in the tests with GenX."

GenX is also a forever chemical. When PFOA was banned, GenX was one of the most widely used chemicals to replace it. And a growing body of evidence suggests that GenX could be just as big an environmental problem as its predecessor.

"It's a similar story to PFOA," Wong said. "They're finding GenX everywhere now. But one difference between the two is that people have previously reported some success with catalysts for degrading PFOA. They haven't for GenX."

Wong and colleagues found that boron nitride powder also destroys GenX. The results weren't as good as with PFOA: With two hours exposure to 254-nanometer light, BN destroyed about 20% of the GenX in water samples. But Wong said the team has ideas about how to improve the catalyst for GenX.

He said the project has already attracted the attention of several industrial partners in the Rice-based Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment (NEWT). NEWT is an interdisciplinary engineering research center funded by the National Science Foundation to develop off-grid water treatment systems that both protect human lives and support sustainable economic development.

"The research has been fun, a true team effort," Wong said. "We've filed patents on this, and NEWT's interest in further testing and development of the technology is a big vote of confidence."

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Additional study co-authors include Kimberly Heck, Sujin Guo, Chelsea Clark, Jacob Arredondo and Thomas Senftle, all of Rice; Minghao Wang, Xianghua Wen and Yonghui Song, all of Tsinghua University; and Paul Westerhoff of Arizona State University.

The research was supported by the National Science Foundation (EEC-1449500) and the China Scholarship Council.

Links and resources:

The DOI of the study is: 10.1021/acs.estlett.0c00434

A copy of the Environmental Science and Technology Letters study is available at: https://doi.org/10.1021/acs.estlett.0c00434

IMAGES available for download:

https://news-network.rice.edu/news/files/2020/07/0706_PHOTOCAT-fig2-lg.jpg

CAPTION: An illustration of the boron nitride photocatalysis that destroys the pollutant PFOA in water. (Image courtesy of M. Wong/Rice University)

https://news-network.rice.edu/news/files/2020/07/0706_PHOTOCAT-mw1-lg.jpg

CAPTION: Michael Wong

This release can be found online at news.rice.edu.

Follow Rice News and Media Relations via Twitter @RiceUNews.

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PSYCHEDELIC BREW

Study reveals science behind traditional mezcal-making technique

BROWN UNIVERSITY

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VIDEO: ARTISANS WHO MAKE MEZCAL, A TRADITIONAL MEXICAN SPIRIT, HAVE KNOWN FOR CENTURIES THAT LONG-LASTING BUBBLES ON THE SURFACE OF THE BEVERAGE IS AN INDICATOR THAT IT HAS BEEN DISTILLED TO... view more 

CREDIT: ZENIT LAB / BROWN UNIVERSITY

PROVIDENCE, R.I. [Brown University] -- Artisanal makers of mezcal have a tried and true way to tell when the drink has been distilled to the right alcohol level. They squirt some into a small container and look for little bubbles, known as pearls. If the alcohol content is too high or too low, the bubbles burst quickly. But if they linger for 30 seconds or so, the alcohol level is perfect and the mezcal is ready to drink.

Now, a new study by a team of fluid dynamics researchers reveals the physics behind the trick. Using laboratory experiments and computer models, the researchers show that a phenomenon known as the Marangoni effect helps mezcal bubbles linger a little longer when the alcohol content is around the sweet spot of 50%. In addition to showing the scientific underpinnings of something artisans have known for centuries, the researchers say the findings reveal new fundamental details about the lifetimes of bubbles on liquid surfaces.

The study, a collaboration between researchers at Brown University, Universidad Nacional Autónoma de México, Université de Toulouse and elsewhere, was published on July 3 in the journal Scientific Reports.

When Roberto Zenit, a professor in Brown's School of Engineering and the study's senior author, first heard about the bubble trick, he said he was instantly intrigued.

"One of my main research interests is bubbles and how they behave," Zenit said. "So when one of my students told me that bubbles were important in making mezcal, which is a drink that I really enjoy with my friends, it was impossible for me not to investigate how it works."

The researchers started by doing experiments to see how changing the alcohol level of mezcal changed bubble lifetimes. They watered down some samples of mezcal and added pure ethyl alcohol to others. They then reproduced the squirting trick in the lab while carefully timing the bubbles. They found that, sure enough, alcohol level dramatically affected bubble lifetimes. In unaltered samples, bubbles lasted from 10 to 30 seconds. In both the fortified and watered-down samples, the bubbles burst instantly.

Having shown that bubbles really can be a gauge of alcohol content, the next step was to figure out why.

To do that, the Zenit and his students started by simplifying the fluid -- performing experiments with mixtures of just pure water and alcohol. Those experiments showed that, as with mezcal, bubbles tended to last longer when the mixture was near 50% water and 50% alcohol. The researchers determined that the extra bubble life was due largely to viscosity. Bubbles tend to last longer in more viscous fluids, and the viscosity of alcohol-water mixtures peaks right around 50%.

However, the bubbles in the 50-50 water and alcohol mixtures still didn't last as long as those in mezcal. Zenit and his students realized there must be something about mezcal that amplifies the viscosity effect. To figure out what it was, they used high-speed video cameras to carefully watch the bubbles through their lifetimes.

The video revealed something surprising, Zenit said. It showed an upward convection of liquid from the surface of mezcal into the bubble membranes.

"Normally, gravity is causing the liquid in a bubble film to drain away, which eventually causes the bubble to burst," Zenit said. "But in the mezcal bubbles, there's this upward convection that's replenishing the fluid and extending the life of the bubble."

With the help of some computer modeling, the researchers determined that a phenomenon known as the Marangoni convection was responsible for this upward motion. The Marangoni effect occurs when fluids flow between areas of differing surface tension, which is the attractive force between molecules that forms a film surface of a fluid. Mezcal contains a variety of chemicals that act as surfactants -- molecules that change the surface tension. As a result, bubbles that form on the surface of mezcal tend to have higher surface tension than the surfactant-filled fluid below. That differing surface tension draws fluid up into the bubble, increasing its lifespan.

By amplifying the existing tendency for longer-lasting bubbles in 50% alcohol mixtures, the surfactant-driven Marangoni effect makes bubbles a reliable gauge of alcohol content in mezcal.

Zenit, who hails from Mexico, said it was gratifying to shed new light on this artisanal technique.

"It's fun to work on something that has both scientific value and cultural value that's part of my background," he said. "These artisans are experts in what they do. It's great to be able to corroborate what they already know and to demonstrate that it has scientific value beyond just mezcal making."

The insights generated from the work could be useful in a variety of industrial processes that involve bubbles, the researchers said. It could also be useful in environmental research.

"For example," the researchers write, "the lifetime of surface bubbles could be used as a diagnostic tool to infer the presence of surfactants in a liquid: If the lifetime is larger than that expected of a pure/clean liquid, then the liquid is most likely contaminated."

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