It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Monday, November 25, 2024
The human heart may have a hidden ability to repair itself
Karolinska Institutet
After severe heart failure, the ability of the heart to heal by forming new cells is very low. However, after receiving treatment with a supportive heart pump, the capacity of a damaged heart to repair itself with new muscle cells becomes significantly higher, even higher than in a healthy heart. This is according to a new study from Karolinska Institutet in Sweden published in the journal Circulation.
The ability of the human heart to renew itself by regenerating its muscle cells, myocytes, is very limited. But what happens to this capability when the heart is damaged by severe heart failure has been unknown.
Researchers at Karolinska Institutet have now discovered that after an injury, the rate of cell renewal is even lower than in a healthy heart. Standard-of-care for patients with advanced heart failure is a surgically implanted pump that helps propel blood, a so-called left ventricular assist device (LVAD).
Kick-start the repair mechanism
Surprisingly, the researchers found that patients with such a heart pump, who have shown significant improvement in their heart function, can regenerate heart muscle cells at a rate more than six times higher than in healthy hearts.
“The results suggest that there might be a hidden key to kick-start the heart’s own repair mechanism”, says Olaf Bergmann, senior researcher at the Department of Cell and Molecular Biology at Karolinska Institutet and last author of the paper.
The mechanism behind the effect is still unknown and there is not yet any hypothesis to explain it.
“It is difficult to say. In the existing data we cannot find an explanation for the effect, but we will now continue to study this process at a cellular and molecular level,” says Olaf Bergmann.
The findings open the possibility of developing new therapies for patients with serious heart conditions that stimulate the heart’s ability to repair itself after damage. This way, patients wouldn’t have torely only on heart transplants or other kinds of long-term mechanical support.
“This offers some hope that the recovery after a heart incident can somehow be boosted,” says Olaf Bergmann.
Determine the age of cells
It is generally difficult to determine the age of cells in the human body and to decide which cells are new and which are old. However, by using a method earlier devised by Jonas Frisén, professor of stem cell research at Karolinska Institutet, the group has been able to count the rate of renewal of myocytes in the heart. The method is based upon the fact that the percentage of radioactive carbon in the atmosphere, and subsequently in our cells, has steadily decreased since the nuclear test ban in 1963. For every following year, there is a little less radioactivity in newly formed cells, which means that they can be ‘dated’.
The study was done in close collaboration with Stavros Drakos at the University of Utah, USA, and was mainly financed by the Swedish Research Council, LeDucq Foundation and the Ragnar Söderberg Foundation. There are no reported conflicts of interest.
Publication:“A latent cardiomyocyte regeneration potential in human heart disease”, Wouter Derks, Julian Rode, Sofia Collin, Fabian Rost, Paula Heinke, Anjana Hariharan, Lauren Pickel, Irina Simonova, Enikő Lázár, Evan Graham, Ramadan Jashari, Michaela Andrä, Anders Jeppsson, Mehran Salehpour, Kanar Alkass, Henrik Druid, Christos P. Kyriakopoulos, Iosif Taleb, Thirupura S. Shankar, Craig H. Selzman, Hesham Sadek, Stefan Jovinge, Lutz Brusch, Jonas Frisén, Stavros Drakos, Olaf Bergmann, Circulation, online 21 November 2024, doi: 10.1161/CIRCULATIONAHA.123.067156.
A Kennesaw State University researcher recently earned a National Science Foundation (NSF) grant to study the evolution of salamanders’ behavioral habits in urban streams, which will in turn fund more undergraduate research opportunities for KSU students.
Assistant professor of biology Todd Pierson has received a three-year, $380,238 grant from the NSF through a program called Building Research Capacity in Biology (BRC-BIO). The program is designed to broaden research participation at minority-serving universities and Carnegie-designated R2 institutions like KSU.
“At KSU we have nearly 48,000 students, and tons of them are interested in doing research,” said Pierson, who teaches in the College of Science and Mathematics. “This study will consist of a team research class of about 15 students each fall so that they're getting something that’s a more authentic, full research experience. That’s the goal.”
Pierson joined KSU’s Department of Ecological, Evolutionary and Organismal Biology in 2020, bringing with him expertise in salamanders. These tiny amphibians can found by the thousands in Atlanta-area waterways and provide examples in genetic and behavioral variation in a relatively small geographical area.
“Even within a species, every individual looks and acts differently, and some of the most interesting questions in evolutionary biology have to do with where that variation comes from, and how it persists in a population,” he said. “Sometimes it’s hard to trace because traits have many genetic components related, and a bunch of environmental variables that affect it. But in other cases, we have a relatively straightforward genetic determinant of these traits, and we can trace it and better understand how it changes across time and space.”
The study focuses on the two-lined salamanders, an ecologically crucial amphibian commonly found in Atlanta-area waterways. This species has two kinds of males—a male that seeks out mates on land and a male that guards mates in the water—and Pierson said his researchers will survey several streams and creeks around Atlanta to determine the proportions of each kind of male relative to the total population.
The Pierson lab seeks answers to key questions, including the evolutionary history of salamanders, the reproductive behavior of salamanders, and the conservation of salamanders and their habitat. The study will take into account factors such as stream size, water temperature, and the presence of pollutants among other things. In other words, it will create a true experience in field research for undergraduate students.
“For these students, the whole function of their semester-long class is to conduct a research project together,” he said. “The students will have autonomy and creativity in determining the course of their studies, which is what we try to do at KSU.”
Cary scientists act fast to study spongy moth impacts on disease-carrying ticks
Spongy moth caterpillars defoliated Hudson Valley forests this summer. Is that good or bad news for ticks that carry Lyme disease? With a RAPID grant from the National Science Foundation, Cary scientists aim to find out.
Cary Institute of Ecosystem Studies
image:
Photos taken at the same location on the Cary Institute's grounds on May 21, 2024 (left) and June 4, 2024 (right).
Credit: Photo: Mike Fargione/Cary Institute of Ecosystem Studies
(Millbrook, NY) In June, Cary Institute’s hardwood forest — stripped of its foliage by hordes of invasive spongy moth caterpillars — more closely resembled a savanna. Standing in a grassy area doused in sunlight, Kelly Oggenfuss pointed out, “This spot would normally be a lot shadier, and the ground would be covered in leaf litter.”
Oggenfuss has been collecting data at this site for 25 years as part of Cary’s long-term project studying the ecology of tick-borne diseases, and she had never seen it like this before.
Cary’s campus in Millbrook, NY, was hit hard by the invasive spongy moth this spring and summer. Defoliation of oak trees — the pest’s favorite food — reached nearly 100%, and other species, including evergreens, suffered significant damage. Cary was not alone; the caterpillars denuded much of the Mid-Hudson Valley region before they died or retreated into cocoons, allowing the trees to unfold new leaves.
Because Oggenfuss and the tick ecology team — led by Cary disease ecologists Richard Ostfeld and Shannon LaDeau — had already been studying how heat and moisture at the ground level shapes tick survival, the team realized the sudden increase in light due to defoliation might have serious implications for ticks and the diseases they spread to humans. So they applied for, and quickly won, a RAPID grant from the National Science Foundation. RAPID grants are fast-tracked to allow scientists to study unanticipated and fast-changing conditions.
With an award of $179,544, the team sprang into action, scaling up the experiments they had already started. The one-year project is assessing how spongy moth defoliation shapes the survival of blacklegged ticks, the main vectors of the pathogens that cause Lyme disease, babesiosis, and anaplasmosis.
“We know from our previous research that if it's very warm and dry, that's really bad for some life stages of ticks,” said Ostfeld. “So if this defoliation by the spongy moths is changing temperature and humidity conditions on the ground, it could influence their survival, and as a consequence, our risk of getting sick from tick-borne disease.”
To examine the impacts on ticks, the team set up 144 mesh enclosures. The enclosures are bags made of white organza, the same material often used in wedding party favors. However, the contents are definitely not suitable for a party. Each bag contains a small cylinder of the natural layer of soil and leaf litter, two data loggers the size of watch batteries that record temperature and humidity, and a certain number of blacklegged ticks. The crew ties each bag, trapping the ticks inside, then comes back in a few weeks to count how many survived.
Under the RAPID grant, the tick enclosures are evenly deployed in three kinds of conditions: heavily defoliated areas, areas with lower defoliation, and in defoliated locations under a shade cloth to simulate an intact canopy. The team will measure tick survival under each condition, and with each tick life stage. They started with larvae in September. Next they’ll deploy adults in November, and nymphs in May 2025, matching their natural seasonal patterns.
Ostfeld and LaDeau hypothesize that ticks in the most defoliated areas will experience warmer and drier conditions, and therefore higher mortality rates. However, ecological responses to change are notoriously complex and unpredictable, and the team is prepared for nature to throw a curveball. For example, the scientists have already observed that more light coming through to the forest floor has allowed understory plants to thrive in areas where they’re normally not found.
“The crew was blown away by the degree to which grasses and forbs underwent this amazing flush of growth in the understory,” said Ostfeld. “So in terms of the impact on ticks, it could go either way. It could be that the loss of leaves from the trees makes it hotter and drier and kills a lot of ticks. Or it could be that the loss of leaves from the trees makes conditions just lovely for ticks, because of all this flush of greenery.”
In another interesting dynamic, the flush of ground-level plants seems to have welcomed large numbers of meadow voles into the study sites, where they’re not commonly found. This influx could mean that many ticks will feed on voles instead of mice and chipmunks. Voles are less likely to pass pathogens to the ticks, and may be more likely to kill the ticks that bite them, and therefore could influence tick survival and disease risk.
Cary scientists are uniquely poised to keep a finger on the pulse of these dynamics, as they’ve been studying interactions like these for almost 35 years.
The long-term project has revealed connections between acorn production, rodent population size, and ticks that carry Lyme disease bacteria. When oak trees drop a lot of acorns in the fall, for example, the all-you-can-eat acorn buffet can lead to surges in populations of white-footed mice and other rodents the following year. Ticks are then more likely to feed on these rodents, which happen to be very good at sharing the bacteria that cause Lyme disease. Hence, more ticks are then capable of spreading Lyme disease if they bite a human the following year.
Over the years, the team has investigated many other ecological dynamics surrounding these interactions. Predators such as foxes and bobcats can lower Lyme disease risk, they learned, possibly by killing and eating rodents, and/or serving as an alternate food source for ticks. The team also discovered that years with high numbers of mice and chipmunks can be devastating for birds that nest on the ground, as the rodents are more likely to eat their eggs and young.
This isn’t the first time spongy moths have been included in the long-term experiment. Many years ago, the project revealed that when mice are abundant, they have some capacity to regulate spongy moth populations by eating the moth’s cocoons.
“Now we’re coming at it from a new angle,” said Ostfeld. “It’s the same players, but different interactions.”
As part of the long-term project, the team had already deployed soil cores and were tracking microhabitat data when the spongy moth infestation exploded. Those data will no doubt prove useful in understanding how defoliation affects tick survival, but the RAPID grant allowed the team to rapidly scale up their efforts.
“The level of defoliation this summer was a surprise to all of us,” said LaDeau. “It's pretty remarkable that we were able to respond and get funding and start studying it as quickly as we did. And a lot of that wouldn't have happened without the longer-term project in place.”
The new study will clarify how dramatic ecological changes — from spongy moth infestations to the hotter and drier conditions projected in some locations — influence tick survival, and what that means for people. LaDeau and Ostfeld are eager to plug their findings into a custom model they’ve been developing with collaborators to generate real-time forecasts of tick populations and local risk of Lyme disease.
Finding out whether the ticks thrive or “take it on the chin,” in Ostfeld’s words, may turn out to be key to understanding that risk over the next few years.
Project assistant Marie Young uses a paint brush to gently add ticks to a soil core enclosure. She is surrounded by burnweed, a species that never occurred on these forested plots before the spongy moth defoliation.
Credit
Photo: Morgan Lilley/Cary Institute of Ecosystem Studies
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Cary Institute of Ecosystem Studies is an independent nonprofit center for environmental research. Since 1983, our scientists have been investigating the complex interactions that govern the natural world and the impacts of climate change on these systems. Our findings lead to more effective resource management, policy actions, and environmental literacy. Staff are global experts in the ecology of: cities, disease, forests, and freshwater.
Animal characters can boost young children’s psychological development, study suggests
University of Plymouth
Children’s books are full of animal characters whose antics capture the hearts and inspire the imaginations of their young readers.
However, a new study has shown that iconic characters such as Peter Rabbit – or Toad and Ratty from The Wind in the Willows – can also play an important role in children’s psychological development.
The research explored the extent to which different non-human characters influence children’s theory of mind skills, which include the ability to read and predict social changes in the environment through tone of voice, choice of words, or facial expression.
For the study, more than 100 children aged between five and 10 were tested on their theory of mind skills when presented with stories featuring animal characters as opposed to those featuring human ones.
The study found that when faced with human characters, there was a clear age-related progression, with older children consistently outperforming their younger counterparts. In fact, Year 3 children performed better than the researchers had predicted in the tests featuring human characters.
However, in tests that involved animal characters, Year 1 participants were able to match the scores achieved by pupils from Year 3, two years older than them.
Writing in the Journal of Experimental Child Psychology, the researchers say the findings highlight the importance of both human and non-human characters for children’s earliest development.
The research was led by Dr Gray Atherton and Dr Liam Cross, from the University of Plymouth’s School of Psychology.
Dr Atherton, lead author on the new study, said: “Animals play a huge part of children’s stories, whether that is in books and comics or through TV and film. We wanted to test if that is down to more than simply liking the characters, and whether there are actual benefits of children learning through by watching or reading about animals and if this changes over time. Our findings showed that both human and non-human characters are important in helping children interpret the world around them, and that they play differing roles at different stages in their development. Adapting activities and lessons in nurseries and the early school years to take that into account could be hugely effective in helping to support their development.”
The research builds on previous studies by Dr Atherton and Dr Cross exploring factors which can influence the educational and social development of people with autism and learning difficulties.
These have included initiatives showing that playing board and online games can boost the confidence among people with autism, and others highlighting that people with dyslexia and dyscalculia show reduced bias against others based on characteristics such as their disability, race or gender.
Based on the new research, the academics now intend to explore in more detail if their findings could be used specifically to benefit children with such conditions.
Dr Cross added: “We believe this new study could have particular importance for people with autism or other conditions which can impact their learning. Working with teenagers in the past, we have noticed how tasks that involve animal characters can result in autistic people performing just as well as non-autistic children. It would be interesting to replicate our current study with autistic children, to understand if we can find more effective ways to support them at a critical point in their development.”
The wind in the willows effect: Does age affect human versus animal faux pas recognition?
Article Publication Date
2-Nov-2024
Standing at work can be detrimental to blood pressure
FIRST IT WAS TOO MUCH SITTING AT WORK NOW ITS TOO MUCH STANDING
University of Turku
A Finnish study found that prolonged standing at work had a negative impact on the research participants’ 24-hour blood pressure. In contrast, spending more time sitting at work was associated with better blood pressure. The study suggests that activity behaviour during working hours may be more relevant to 24-hour blood pressure than recreational physical activity.
Regular exercise is important for controlling blood pressure. In particular, more vigorous, aerobic exercise is effective for lowering blood pressure, but also everyday physical activity can have a beneficial impact. Previous studies have shown that exercise in leisure time is more beneficial for the cardiovascular system than physical activity at work, which can even be detrimental to health.
24-hour blood pressure important for cardiovascular health
In the Finnish Retirement and Aging study (FIREA) conducted at the University of Turku, the physical activity of municipal employees approaching retirement age was measured using thigh-worn accelerometers during working hours, leisure time, and days off. In addition, the research participants used a portable blood pressure monitor that automatically measured their blood pressure every 30 minutes for 24 hours.
“Rather than any single measurement, 24-hour blood pressure is a better indication of how blood pressure stresses the heart and blood vessels throughout the day and night. If blood pressure is slightly high throughout the day and does not fall sufficiently even at night, blood vessels start to stiffen and the heart has to work harder to cope with the increased pressure. Over the years, this can lead to the development of cardiovascular disease,” says Doctoral Researcher Jooa Norha.
Take a break from standing during the workday
The latest results confirm previous findings that physical activity at work can be harmful to the heart and circulatory system. In particular, prolonged standing can raise blood pressure as the body boosts circulation to the lower limbs by constricting blood vessels and increasing the pumping power of the heart.
“A standing desk can provide a nice change from sitting at the office, but too much standing can be harmful. It's a good idea to take a break from standing during the work day, either by walking every half an hour or sitting for some parts of the day,” Norha recommends.
Recreational physical activity is also needed
In addition, the results of the study suggest that sedentary work in itself is not necessarily harmful to blood pressure. Instead, researchers stress the importance of recreational physical activity for both office and construction workers.
“It is good to remember that being physically active at work is not enough on its own. Engaging in diverse physical exercise during leisure time helps to maintain fitness, making work-related strain more manageable. Similarly, employees with predominantly sedentary jobs should ensure that they get enough exercise during their leisure time,” Norha highlights.
Associations between Leisure and Work Time Activity Behavior and 24 H Ambulatory Blood Pressure among Aging Workers
Exploring factors affecting workers' acquisition of exercise habits using machine learning approaches
University of Tsukuba
Tsukuba, Japan—Physical inactivity is the fourth leading mortality risk factor, following hypertension, smoking, and hyperglycemia. Therefore, acquiring an exercise habit is crucial to maintain and improve health. In Japan, Specific Health Guidance is provided to support the improvement of lifestyle habits, including exercise habits. To develop more efficient health guidance, it is important to identify factors that influence its effectiveness (e.g., characteristics and lifestyle of the target population). In this study, data from middle-aged workers who received Specific Health Guidance were analyzed using machine learning to explore the factors associated with the acquisition of exercise habits, and the importance of each factor was evaluated.
The researchers conducted a secondary analysis of data obtained by health insurance societies and other organizations through health projects in 2017-2018. They found that the most critical factor associated with the acquisition of exercise habits was "the higher stages of behavioral change toward lifestyle improvement," followed by "high level of physical activity" and "high density lipoprotein cholesterol level being within the reference range." In contrast, "daily alcohol consumption of ≥60 g" had a negative effect on the acquisition of exercise habits.
This study revealed the factors related to the characteristics and lifestyles of middle-aged workers who received Motivational Health Guidance under the Specific Health Guidance program that positively associate with the acquisition of exercise habits. The results of this study may contribute to developing more efficient health guidance.
### This work was supported by the Japan Agency for Medical Research and Development (grant numbers 21ek0210124h9903 and JP23rea522107).
Original Paper
Title of original paper: Factors associated with acquiring exercise habits through health guidance for metabolic syndrome among middle-aged Japanese workers: A machine learning approach
Factors associated with acquiring exercise habits through health guidance for metabolic syndrome among middle-aged Japanese workers: A machine learning approach
AMERIKA
Disparities by race and urbanicity in online health care facility reviews
JAMA Network
About The Study: This serial cross-sectional study observed a significant decrease in positive reviews for health care facilities post-COVID. These findings underscore a disparity in patient experience, particularly in rural areas and areas with the highest proportions of Black and white residents.
Corresponding Author: To contact the corresponding author, Neil K. R. Sehgal, ME, email neilsehgal99@gmail.com.
Editor’s Note: Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and funding and support.
About JAMA Network Open: JAMA Network Open is an online-only open access general medical journal from the JAMA Network. On weekdays, the journal publishes peer-reviewed clinical research and commentary in more than 40 medical and health subject areas. Every article is free online from the day of publication.
Journal
JAMA Network Open
Racial and ethnic variation in survival in early-onset colorectal cancer
JAMA Network
About The Study: In this cohort study, racial and ethnic disparities in early-onset (before 50 years of age) colorectal cancer mortality were evident, with the highest burden among Native Hawaiian or Other Pacific Islander and non-Hispanic Black individuals. These results provide evidence of the role of social determinants of health in explaining these differences.
Corresponding Author: To contact the corresponding author, Maria Elena Martinez, PhD, email e8martinez@health.ucsd.edu.
Editor’s Note: Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and funding and support.
About JAMA Network Open:JAMA Network Open is an online-only open access general medical journal from the JAMA Network. On weekdays, the journal publishes peer-reviewed clinical research and commentary in more than 40 medical and health subject areas. Every article is free online from the day of publication.
Journal
JAMA Network Open
Caste differentiation in ants
University of Copenhagen - Faculty of Science
Most ants have two morphologically differentiated adult castes - queens and workers - each irreversibly specialized for either reproduction or nonreproductive altruism such as foraging, defense and care of maternal brood. Adult gynes (virgin queens) normally have higher body mass, wings and frontal eyes, as well as enlarged ovaries and a sperm storage organ. In contrast, workers are wingless females with smaller body size and degenerated reproductive tracts, usually without a sperm storage organ. In 1910, the American entomologist William Morton Wheeler noted in his monograph Ants that the superorganismal colonies of ants are strikingly analogous to metazoan bodies because queen and workers function as germline and soma at a higher level of bodily organization: the colony-level.
We are very used to the idea that germline cells in an animal body are set aside for their special reproductive roles very shortly after an egg is fertilized and starts to develop into an embryo. In most social insects with distinct queen (colony germline) and worker (colony soma) castes the analogous developmental differentiation happens in the larval stage and can still be hormonally reversed. However, in some ants colony germlines are also determined earlier, in the embryonic (egg) stage, begging the question whether that makes somatization of workers as irreversible as somatization of animal body cells as development proceeds.
A new study from the Department of Biology at the University of Copenhagen, funded by a Villum Investigator Grant,finds that caste development is remarkably reversible in pharaoh ants, Monomorium pharaonis, a species where caste determination happens in the eggs stage. “We fed 237 pharaoh ant worker larvae with controlled doses of juvenile hormone (JH) analog during the 3rd larval instar, the final stage of larval development”, says Ruyan Li, the lead author of this study. “We found that hormone-treated worker ants developed many gyne-like physical characteristics, such as increased body length, three extra frontal eyes, wings and flight muscles, gyne-like brains; they even developed the gyne-specific sperm storage organ that workers of this species never have”.
However, unlike naturally developed gynes, JH-treated workers never developed ovaries, the reproductive organ that ultimately sets gynes apart from workers, show that the caste-specific JH-sensitivity window does not overlap with the egg-stage. The study also sheds new light on how shifts in developmental-sensitivity for growth hormone may have played a role in the emergence of new castes in other ants, such as soldiers (modified workers) or permanently wingless gynes. “Such novel castes often originate as mosaic phenotypes that recombine gyne- and worker traits, which may become permanent when natural selection rewards a subsequent shift in JH-sensitivity window”, says Guojie Zhang, corresponding author of the study and Professor at Zhejiang University in Hangzhou and Adjunct Professor at the University of Copenhagen.
- “The results confirm the strong analogy between how cell differentiation in animal bodies and caste differentiation in ant colonies works. Similar to animal breeders having not yet succeeded in using somatic cells to produce new animals, this study found similar limitations at the higher level of colonial organization in ants”, concludes Professor Koos Boomsma at the University of Copenhagen, a senior coauthor of the study.
3D-printing advance mitigates three defects simultaneously for failure-free metal parts
University of Wisconsin-Madison
image:
From left: Associate Professor Lianyi Chen and PhD students Jiandong Yuan and Ali Nabaa work on developing beam shaping approaches for defect-lean and high productivity metal additive manufacturing.
University of Wisconsin–Madison engineers have found a way to simultaneously mitigate three types of defects in parts produced using a prominent additive manufacturing technique called laser powder bed fusion.
Led by Lianyi Chen, an associate professor of mechanical engineering at UW–Madison, the team discovered the mechanisms and identified the processing conditions that can lead to this significant reduction in defects. The researchers detailed their findings in a paper published on November 16, 2024, in theInternational Journal of Machine Tools and Manufacture.
“Previous research has normally focused on reducing one type of defect, but that would require the usage of other techniques to mitigate the remaining types of defects,” Chen says. “Based on the mechanisms we discovered, we developed an approach that can mitigate all the defects — pores, rough surfaces and large spatters — at once. In addition, our approach allows us to produce a part much faster without any quality compromises.”
Multiple industries, including aerospace, medical and energy, are increasingly interested in using additive manufacturing, also known as 3D printing, to produce metal parts with complex shapes that are difficult or impossible to create using conventional methods.
But the big challenge is that metal parts created with additive manufacturing have defects — like pores, or “voids,” rough surfaces and large spatters — that significantly compromise the finished part’s reliability and durability. These quality problems prevent 3D-printed parts from being used for critical applications where failure is not an option.
By providing a path for simultaneously increasing part quality and manufacturing productivity, the UW–Madison team’s advance could lead to widespread industry adoption of laser powder bed fusion.
Laser powder bed fusion uses a high-energy laser beam to melt and fuse thin layers of metal powder, constructing a part layer by layer from the bottom up. In this research, the UW–Madison team used an innovative ring-shaped laser beam, provided by a leading laser company called nLight, instead of the usual Gaussian-shaped beam.
The ring-shaped laser beam played a key role in this breakthrough — as did critical “in-situ” experiments, says Jiandong Yuan, the lead author of the paper and a PhD student in Chen’s group.
To see how the material behaved within the part as it was printing, researchers went to the Advanced Photon Source, an ultra-bright, high-energy synchrotron X-ray user facility at Argonne National Laboratory. Combining high-speed synchrotron X-ray imaging, theoretical analysis and numerical simulation, the researchers revealed the defect mitigation mechanisms, which involve phenomena that reduce instabilities in the laser powder bed fusion process.
The researchers also demonstrated that they could use the ring-shaped beam to drill deeper into the material without causing instabilities in the process. This enabled them to print thicker layers, increasing the manufacturing productivity. “Because we understood the underlying mechanisms, we could more quickly identify the right processing conditions to produce high-quality parts using the ring-shaped beam,” says Chen.
Lianyi Chen is the Kuo K. & Cindy F. Wang Associate Professor of mechanical engineering.
Collaborators from UW-Madison include Qilin Guo, Luis Escano, Ali Nabba, Minglei Qu, Junye Huang, Qingyuan Li, Allen Jonathan Román, and Professor Tim Osswald. Samuel Clark and Kamel Fezzaa from Argonne National Laboratory also collaborated on this project.
This work was supported by the National Science Foundation and the Wisconsin Alumni Research Foundation.
