How to make nitrogen more accessible to crops

New review article examines the role an enzyme plays in converting nitrogen into ammonium and preventing runoff

Michigan State University

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Eric Hegg is dean of the Michigan State University College of Natural Science.

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Credit: David Trumpie

A microscopic enzyme could be the key to helping nitrogen fertilizers stick better to the soil and prevent run-off that causes harmful algal blooms, according to a new review article published by a Michigan State University research team.

Led by College of Natural Science Dean Eric Hegg, the paper compiles years of research on an enzyme known as NrfA that plays a key role in keeping nitrogen in soil. Krystina Hird, an MSU Ph.D. candidate and first author on the paper, said studying NrfA could help farmers not only avoid polluting nearby waterways but also save money by reducing their need for fertilizer.

“A significant amount of nitrogen fertilizer is lost because it’s converted to a form that’s easily leached away,” Hird said. “If we can retain more of that nitrogen in the soil, it could have big, positive agricultural implications.”

Nitrogen is an essential element for all living things, from humans down to the smallest bacteria. It’s commonly added to farm fields in a variety of forms to boost crop yields. The problem is both soil and nitrites are negatively charged. Just as magnets of the same charge repel one another, nitrites are easily washed away from farm fields during heavy rains. When too much nitrogen ends up in lakes and rivers, the result can be harmful algal blooms that make waterways toxic to humans and animals.

One of the best forms of nitrogen for agriculture is ammonium. With its positive charge, it latches onto soil and is more easily taken up by plants. However, many microbes in the soil turn ammonium into nitrite.

That’s where NrfA comes in. Not only does it help the bacteria turn nitrite into ammonium, but it does so while moving and storing electrons incredibly efficiently. This aspect of the research drew interest from the U.S. Department of Energy, which funded the research. Other enzymes can help produce ammonium, but not as quickly or efficiently as NrfA.

While many researchers have contributed to this field, the findings aren’t centrally located. Hegg’s team combed through primary research, collated it into a review paper and synthesized the findings to draw larger conclusions.

“I’m excited to help future students who were in my shoes, who are just getting into this field and are trying to understand this big project that they’re agreeing to take on for the next five to six years,” Hird said. “We decided to take all of this information and put it in one place as an introduction-level paper for those graduate students.”

Farmers could use the review paper’s conclusions to help them choose the best nigrogen-containing fertilizers for their fields. More research could also be done to determine how bacteria with NrfA could be strategically placed along the edges of fields where water is most likely to run downhill, Hird said. A step in between those options could be encouraging the growth of more soil microorganisms that can produce ammonium by balancing the carbon to nitrogen ratio in the soil.

Next, Hegg’s team plans to dive deeper into the mechanism of how nitrate is converted into ammonium. They want to track how electrons move through NrfA and how it consistently produces ammonium, even when starting with different nitrogen compounds.

“We’re trying to get really specific and nitty-gritty,” Hird said. “The reaction goes so fast, and slowing down a very fast reaction can make it unstable. It’s going to be like performing a delicate surgery.”

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Journal

Applied and Environmental Microbiology

DOI

10.1128/aem.00292-25 

Method of Research

Literature review

Subject of Research

Cells

Article Title

From genes to function: regulation, maturation, and evolution of cytochrome c nitrite reductase in nitrate reduction to ammonium

Article Publication Date

9-Jun-2025

 

New soil models improve safety of wheat amid cadmium contamination

Nanjing Institute of Environmental Sciences, MEE

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This schematic illustrates the full workflow of a new study that integrates field and literature data, correlation analysis, and predictive modeling—including machine learning and geochemical approaches—to assess cadmium accumulation in wheat. The framework enables accurate estimation of soil cadmium thresholds based on food safety standards, offering a powerful tool for safeguarding wheat production in contaminated regions.

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Credit: The authors

A new study offers a new solution to tackle cadmium contamination in wheat, one of China’s most vital staple crops. Scientists have developed a suite of predictive models that estimate cadmium levels in wheat grain using soil characteristics. Among these, a machine learning model dramatically outperformed traditional methods, enabling faster and more precise risk assessments. By analyzing 311 soil-wheat samples collected from across China, the researchers identified soil pH, cadmium content, and cation exchange capacity as key drivers of metal uptake. The study also introduced improved soil cadmium thresholds that better reflect food safety needs, offering a practical path toward safer and more sustainable wheat production.

Cadmium (Cd), a toxic heavy metal, poses a growing threat to food safety through its accumulation in crops. Wheat, in particular, tends to absorb more cadmium than rice due to its higher internal transport efficiency. In China’s rice–wheat rotation systems, wheat grains often exceed cadmium safety limits, despite adherence to national soil quality standards. Recently revised regulations have introduced stricter soil cadmium limits, but they may result in unnecessary costs and over-regulation. Earlier predictive models have fallen short, failing to capture the complexity of real soil conditions. Due to these challenges, there is a pressing need for more accurate, field-validated models to ensure wheat safety without overburdening producers.

On May 14, 2025, researchers from Nanjing University and Columbia University published a study (DOI: 10.1016/j.eehl.2025.100154) in Eco-Environment & Health that unveils new models to predict cadmium accumulation in wheat grain. Using data from 311 paired soil and wheat samples across China, the team compared multiple regression, machine learning, and geochemical approaches. Their aim was to pinpoint the most effective model and generate precise soil cadmium thresholds tied to national food safety standards—offering a more informed framework for protecting wheat from contamination.

The team identified soil total cadmium, pH, and cation exchange capacity (CEC) as the most influential factors in cadmium uptake by wheat. Based on these variables, they built predictive models, including one that used CaCl₂-extractable cadmium to represent the bioavailable fraction most relevant to plant absorption. A geochemical model—the Multi-Surface Speciation Model (MSM)—was also tested for its ability to simulate cadmium behavior under varying soil conditions. While both methods performed well, the standout was the Extremely Randomized Trees (ERT) machine learning model. It achieved a root mean square error (RMSE) of 0.221 and mean absolute error (MAE) of 0.165, outperforming other models in accuracy and adaptability. Crucially, the researchers used these models to back-calculate soil cadmium thresholds based on China’s food safety limit of 0.1 mg/kg for wheat grain. These newly derived thresholds—adjusted for different soil pH levels—proved more effective in predicting grain safety than current national standards, offering a refined and cost-efficient alternative to blanket soil remediation.

"Our goal was to create a practical tool that farmers and regulators can use to assess wheat safety directly from soil data," said Professor Xueyuan Gu, corresponding author of the study. "The machine learning models and new thresholds we developed are not just academic exercises—they can be integrated into field management systems and national monitoring programs." She emphasized the importance of combining scientific rigor with practical usability, noting that broader data collection across regions could further improve the model's reliability and generalizability.

This research has significant implications for agricultural safety and policy development. With these models, cadmium risks can be assessed rapidly and accurately using standard soil tests, empowering farmers and local authorities to make informed decisions about land use. The refined thresholds provide a science-based, economically feasible alternative to rigid remediation policies, helping prevent both under- and over-regulation. Moreover, the successful integration of machine learning marks a broader shift toward data-driven agriculture. As soil databases expand, these predictive tools could evolve into real-time advisory systems—enhancing sustainable land management while protecting public health through safer food production.

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References

DOI

10.1016/j.eehl.2025.100154

Original Source URL

https://doi.org/10.1016/j.eehl.2025.100154

Funding information

This work was financially supported by the Natural Science Foundation of China (42177188, 21876080).

About Eco-Environment & Health

Eco-Environment & Health (EEH) is an international and multidisciplinary peer-reviewed journal designed for publications on the frontiers of the ecology, environment and health as well as their related disciplines. EEH focuses on the concept of "One Health" to promote green and sustainable development, dealing with the interactions among ecology, environment and health, and the underlying mechanisms and interventions. Our mission is to be one of the most important flagship journals in the field of environmental health.

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Journal

Eco-Environment & Health

DOI

10.1016/j.eehl.2025.100154 

Subject of Research

Not applicable

Article Title

Cadmium accumulation in wheat grain: Accumulation models and soil thresholds for safe production

 

Lack of sleep disrupts key brain functions in adolescents

More sleep could protect children’s mental health

University of Georgia

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Your teen’s sleeping habits may affect how their brain functions, according to new research from the University of Georgia. And lack of quality sleep may put kids at risk of developing problem behaviors in the future.

The study found that adolescents who got less sleep had less connectivity between the parts of the brain that play a critical role in decision making, self-reflection and processing information. Malfunctions in these parts of the brain are also linked to mental illnesses such as depression, ADHD and schizophrenia.

The children with less brain connectivity in this region were more likely to exhibit behavioral issues like acting out, poor impulse control and aggressiveness.

“Sleep isn’t just good for children. It helps keep their mental health intact and helps them regulate their emotions,” said Assaf Oshri, corresponding author of the study and a professor in the UGA College of Family and Consumer Sciences. Oshri also serves as director of the UGA Georgia Center for Developmental Science.

“The paper shows that sleep duration and sleep efficiency are linked to distinct patterns of brain network connectivity that are predictive of problem behaviors.”

The study suggests that interventions targeted at increasing adolescents’ sleep could help prevent conduct problems in the future.

Boys, minority children at risk of problem behavior due to lack of sleep

The researchers relied on data from the Adolescent Brain and Cognitive Development Study, which is the largest long-term study of brain development and child health in the U.S.

The present study followed more than 2,800 adolescents, using Fitbits to objectively track how well and for how long the children slept for an average of two weeks. The researchers compared that data with the same children’s MRIs. The imaging identified distinct patterns in connectivity between brain regions.

The children’s parents also reported on problem behaviors during the second and third year.

Boys, older children and kids from minority races tended to have shorter periods of sleep. Boys and minority children were also more likely to demonstrate problem behaviors in the second and third years of the study period.

Adolescence critical period for brain development

The study’s findings suggest the effects of frequent nights of too little sleep snowball.

“Adolescence is an extremely critical period for brain development,” said Linhao Zhang, lead author of the study and a recent doctoral graduate of the College of Family and Consumer Sciences. “And sleep is critical for brain development. But many adolescents don’t get enough quality sleep at night.”

That lack of quality sleep can make it more difficult for children to learn to regulate their emotions and control their impulses.

“How adolescents sleep influences how their brains function, and that influences their mental health outcomes,” Zhang said. “It’s not just about how long you slept. It’s how well did you sleep? Did you take a long time to fall asleep? Did you wake up in the middle of the night?”

Published in Brain and Behavior, the study was co-authored by Charles Geier, a professor in the Department of Human Development and Family Science and associate director of the Georgia Center for Developmental Science, and Dr. Ellen House, an associate professor of psychiatry with the Augusta University/University of Georgia Medical Partnership.

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Journal

Brain and Behavior

DOI

10.1002/brb3.70579 

Article Title

Latent Default Mode Network Connectivity Patterns: Associations With Sleep Health and Adolescent Psychopathology

 

Screen time and emotional problems in kids: A vicious circle?

Children turn to screens to cope, which can lead to more problems, study says

American Psychological Association

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Spending too much time on screens may cause emotional and behavioral problems in children – and those problems can lead to even more screen use, according to research published by the American Psychological Association.

Conducted by an international team of researchers, the study systematically reviewed and meta-analyzed 117 studies, encompassing data from over 292,000 children worldwide. The findings were published in the journal Psychological Bulletin.

“Children are spending more and more time on screens, for everything from entertainment to homework to messaging friends,” said Michael Noetel, PhD, an associate professor in the School of Psychology at Queensland University and one of the authors of the study. “We found that increased screen time can lead to emotional and behavioral problems, and kids with those problems often turn to screens to cope.”

Noetel and his colleagues conducted a meta-analysis to better understand the relationship between screen time and socio-emotional problems, like aggression, anxiety, or low self-confidence. They included any study with participants under 10 years of age that measured screen use and socio-emotional problems, where children were followed-up for at least six months. Screen-based activities included social media, video games, TV watching and online homework. 

Most of the studies were conducted in the United States (41 studies), followed by Canada (13), Australia (11), and Germany and the Netherlands (7 each).

The study revealed that the more children engaged with electronic screens the more likely they were to develop socio-emotional problems. This included both internalizing problems, such as anxiety and depression, and externalizing problems, such as aggression and hyperactivity. Conversely, children experiencing socio-emotional problems were found to be more likely to turn to screens as a coping mechanism.

The researchers identified several factors that may moderate these relationships. Compared with younger children  (ages 0-5), older children (ages 6-10) were more likely to develop socio-emotional problems with greater screen use. Girls were generally more susceptible to developing socio-emotional problems with greater screen use, while boys were more likely to increase screen use when facing socio-emotional challenges.

The type of screen content and purpose of screen use also played a role, according to Noetel. Gaming was associated with higher risks compared with educational or recreational screen use. Children experiencing socio-emotional problems were also more likely to turn to games to cope.

The findings suggest parents might want to be cautious about what screens they allow and use parental controls to manage time, said Noetel. He also noted that kids who use screens heavily might need emotional support, not just restrictions. Parents could benefit from programs helping them handle both screen use and emotional problems.

“This comprehensive study highlights the need for a nuanced approach to managing children's screen time,” said lead author Roberta Vasconcellos, PhD, a lecturer at the University of New South Wales who conducted the research while a doctoral student at Australian Catholic University. “By understanding the bidirectional relationship between screen use and socio-emotional problems, parents, educators and policymakers can better support children's healthy development in an increasingly digital world.”

Because every study in the meta-analysis followed kids over time, the research is a big step closer to cause‑and‑effect (as opposed to correlation) than the usual snapshots done at a single point in time, according to Noetel.

“It’s about as close as we can get to causal evidence without randomly cutting screens for thousands of kids,” he said. “But still, we can’t completely rule out other factors—like parenting style—that could influence both screen use and emotional problems.”

Article: “Electronic screen use and children’s socio-emotional problems: A systematic review and meta-analysis of longitudinal studies,” by Roberta Pires Vasconcellos, PhD, Taren Sanders, PhD, Chris Lonsdale, PhD, Philip Parker, PhD, Diego Vasconcellos, PhD, Katrina Wilhite, PhD, Ella Tremaine, and Bridget Booker, PhD, Australian Catholic University; James Conigrave, PhD, La Trobe University; Samantha Tang, PhD, Black Dog Institute; Borja del Pozo Cruz, PhD, European University of Madrid; Stuart J. H. Biddle, PhD, University of Southern Queensland; Rachael Taylor, PhD, University of Otago; Christine Innes-Hughes, MPH, New South Wales Department of Health; Katariina Salmela-Aro, PhD, University of Helsinki Faculty of Educational Sciences; and Michael Noetel, PhD, University of Queensland. Psychological Bulletin, published online June 9, 2025.

Contact: Michael Noetel, PhD, can be contacted via email at m.noetel@uq.edu.au. Roberta Vasconcellos, PhD can be contacted via email at r.pires_vasconcellos@unsw.edu.au. 

The American Psychological Association, in Washington, D.C., is the largest scientific and professional organization representing psychology in the United States. APA’s membership includes 173,000 researchers, educators, clinicians, consultants and students. Through its divisions in 54 subfields of psychology and affiliations with 60 state, territorial and Canadian provincial associations, APA works to advance the creation, communication and application of psychological knowledge to benefit society and improve lives.

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Journal

Psychological Bulletin

DOI

10.1037/bul0000468 

Method of Research

Meta-analysis

Subject of Research

People

Article Title

Electronic Screen Use and Children’s Socioemotional Problems: A Systematic Review and Meta-Analysis of Longitudinal Studies

Article Publication Date

9-Jun-2025

 

Cancer screenings continue years after guidelines change to limit unnecessary tests, study finds

University of Florida

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Stopping the widespread use of unnecessary, potentially even harmful, cancer screenings can take up to 13 years and potentially even longer after new guidelines are put in place, according to a new study.

Those unnecessary screenings open up patients to potential overdiagnosis, pain and excessive treatment, while costing more money and leading to anxiety and fear.

“Excessive screening opens the door for a lot of negative consequences,” said Jennifer LeLaurin, Ph.D., an assistant professor of health outcomes and biomedical informatics at the University of Florida and lead author of the new study. “These guidelines are based on what the benefits and harms are. If the harms outweigh the benefits for a particular test, then they recommend against it.”

With funding from the National Cancer Institute's Consortium for Cancer Implementation Science, LeLaurin worked with other researchers at the UF College of Medicine, including senior author Naykky Singh-Ospina, M.D., to comb through data about whether outdated cancer screenings were still being used. They focused on new guidelines that recommended against screening for cervical cancer in women younger than 21 or older than 65 and against screening for prostate cancer in men 70 and older.

While it took just a year for screening of cervical cancer to drop by half in young women, it took 13 years to reach that level in women over 65. And despite guidelines put in place in 2012 to stop screening for prostate cancer in older men, screening rates have yet to come down by 50%, the threshold LeLaurin’s team used to determine when widespread screening had ended.

There are a number of barriers to reducing unnecessary screening, including inertia and the widespread interest in catching cancers early.

“To get someone to stop doing something that they’ve been doing for years, it’s really hard. Physicians also have patients with expectations about what tests they want. When you have screening guidelines changing frequently, it’s confusing. It’s especially confusing to patients,” said LeLaurin, who is also a member of the UF Health Cancer Center.

Little information was available for other cancer screenings the researchers wanted to study, because few mechanisms exist to track what happens after new guidelines are released. These included ovarian, thyroid, testicular and pancreatic cancers.

“As physicians and researchers, we’re pretty good about tracking the stuff we’re supposed to be doing. But it’s hard to tell how often some of these screenings that are no longer recommended are happening,” LeLaurin said. “We need more powerful tools to potentially identify where inappropriate screening is taking place.”

Guidelines for who should be screened for which cancers and when are created by the United States Preventive Services Task Force, an independent, volunteer-run research agency supported by the U.S. Department of Health and Human Services. Based on high-quality published research, the task force grades screening tests, with Grade “D” indicating that a test should not be performed in a given group of people because it provides little benefit or even harms patients, on average.

Between 1996 and 2012, the task force released new guidelines recommending against screening for certain cancers, such as ovarian, thyroid, testicular and pancreatic cancer in any patients without symptoms. They also limited the age groups who should be screened for cervical and prostate cancers.

“We need to consider ways to disincentivize inappropriate screening and talk with patients about the benefits and risks of screening and how these guidelines exist to help them,” LeLaurin said

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Journal

BMJ Quality & Safety

DOI

10.1136/bmjqs-2025-018558 

Method of Research

Data/statistical analysis

Subject of Research

People

Article Title

Time to de-implementation of low-value cancer screening practices: a narrative review

 

Ultrasonic vibration enables defect-free machining of ceramic gels

A new non-destructive method for shaping advanced ceramics in the gel state.

Tsinghua University Press

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Ceramic materials are renowned for their hardness and high-temperature resistance, making them indispensable in fields such as aerospace, electronics, and biomedical devices. However, these properties make ceramics difficult to machine without introducing cracks or defects. Traditional machining methods struggle with complex shapes and risk damaging the brittle material.

To address these challenges, researchers led by Professor Shiwei Wang have developed an innovative machining method called URM. This technique processes ceramics in their gel state, formed using Spontaneous Coagulation Casting (SCC), which retains re-flow properties of ceramic gels under shear stress. By applying high-frequency ultrasonic vibration, localized energy precisely modifies the gel’s structure, enabling slotting, drilling, and removing with micrometer-scale accuracy.

The team published their work in Journal of Advanced Ceramics on May 14, 2025.

"The URM method allows us to shape and bond ceramics without cracks," said Shiwei Wang. "It’s a clean, efficient solution that preserves the integrity of the material throughout fabrication." The team demonstrated its feasibility using alumina ceramic gels, achieving smoother surfaces and defect-free joints after sintering. URM also proved superior in reducing surface roughness from 3.2 μm to 0.3 μm.

Importantly, the URM method avoids machining damage and particle pollution often associated with laser cutting or mechanical machining. It also opens new possibilities for complex ceramic geometries previously limited by brittleness. URM's compatibility with environmentally friendly SCC gels further enhances its application in sustainable manufacturing.

The study, published in *Journal of Advanced Ceramics*, is under going to explore the adaptation of URM for other ceramic systems and further optimization of ultrasonic parameters to expand its industrial applicability.

 

About Journal of Advanced Ceramics

Journal of Advanced Ceramics (JAC) is an international academic journal that presents the state-of-the-art results of theoretical and experimental studies on the processing, structure, and properties of advanced ceramics and ceramic-based composites. JAC is Fully Open Access, monthly published by Tsinghua University Press, and exclusively available via SciOpen. JAC’s 2023 IF is 18.6, ranking in Top 1 (1/31, Q1) among all journals in “Materials Science, Ceramics” category, and its 2024 CiteScore is 25.9 (5/130) in Scopus database. ResearchGate homepage: https://www.researchgate.net/journal/Journal-of-Advanced-Ceramics-2227-8508

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Journal

Journal of Advanced Ceramics

DOI

10.26599/JAC.2025.9221091 

Article Title

Ultrasonic-vibration-assisted re-flow machining of ceramic gels