3D-printed knee implants improves quality and reliability

Songshan Lake Materials Laboratory

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(a) Diagrams illustrating how columnar grains develop during the LPBF, contributing to microstructural anisotropy; (b) Stress-strain curves showing significant improvements in the mechanical anisotropy after heat treatment; (c) Diagrams showing the recrystallization process, where equiaxed grains form to eliminate directional effects and enhance uniformity; (d) TEM images revealing the nanoscale interactions between martensite laths in the solution-annealed state; (e) Visual representation of the synergistic effects between annealing twins and martensite laths.

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Credit: Lijin Dai and Changhui Song from South China University of Technology.

Customized 3D-printed medical implants are becoming more common, and a new study has taken this technology to the next level. Researchers at Naton Biotechnology have developed the world’s first laser 3D-printed total knee implant, which has received official approval from China’s National Medical Products Administration as an innovative medical device.

The study focused on improving the strength and consistency of cobalt-chromium-molybdenum (CoCrMo) alloy implants made using laser powder bed fusion (LPBF), a 3D printing process. The team discovered and corrected inconsistencies in the structure of the material by optimizing heat treatment, ensuring the final implants are stronger, more reliable, and safer for patients.

This research provides key insights into how 3D printing affects metal implants and lays the foundation for better quality control in orthopedic manufacturing, helping to advance the future of customized medical implants.

This research was led by Professor Changhui Song from South China University of Technology and Professor Jia-Kuo Yu from Beijing Tsinghua Changgung Hospital as co-corresponding authors. The study was conducted in collaboration with Senior Engineer Renyao Li from Naton Biotechnology (Beijing) Co., Ltd and other members of the team.

The Problem: Uneven Strength in 3D-Printed Metal Implants

The layer-by-layer manufacturing process of CoCrMo, a widely used implant material, occurs at extremely high cooling rates (~10⁵–10⁶ K/s). This rapid solidification often leads to anisotropy, meaning the material's properties vary depending on the direction of force. The main causes include columnar grain structures, porosity, and residual stress, all of which are inherent to additive manufacturing.

While extensive research has been conducted on LPBF-fabricated CoCrMo alloys, most studies have only examined their performance in a single direction, overlooking how anisotropy affects overall durability. However, implants inside the human body must withstand forces from multiple directions. Then, if the material's strength is inconsistent, weak spots can develop, increasing the risk of breakage or failure.

In mechanical tests, CoCrMo samples stretched significantly more in one direction (19.1% elongation) than in another (9.3% elongation)—a disparity of over 100%. This inconsistency makes the material unreliable for long-term medical use, as implants must perform uniformly and safely under everyday stresses.

The Solution: A New Heat Treatment Process

The team found that a two-step heat treatment process significantly improved the uniformity of the metal’s structure and strength. The process included:
Solution Treatment – Heating the material to 1150°C, holding it for an hour, and then rapidly cooling it in water. This helped restructure the uneven metal grains.
Annealing – Reheating the material to 450°C for 30 minutes and then cooling it again. This step refined the grain structure and further balanced the material's properties.
As a result, the metal’s strength and flexibility became nearly identical in all directions. The ultimate tensile strength reached 906.1 MPa and 879.2 MPa, while elongation values balanced at 20.2% and 17.9%, making the material stronger and more reliable for medical use.

The Future: Improving Durability and Biocompatibility

With this breakthrough, scientists are now looking at surface treatments to further enhance the wear resistance and biocompatibility of implants. Methods like shot peening (where tiny metal beads are blasted onto the surface) and ultrasonic peening could improve the fatigue resistance of implants, helping them last longer under daily stress. These next-generation treatments could make 3D-printed joint implants even more durable and widely used in clinical settings.

The Impact: A Safer Future for Medical Implants

This research offers new insights into how to improve 3D-printed metal implants, making them safer and more durable for patients. By addressing uneven strength and material quality, this breakthrough lays the foundation for better orthopedic implants, particularly for joint replacements.
The findings were recently published in the international journal Materials Futures, further advancing research in medical-grade additive manufacturing.

Reference:
Lijin Dai, Changhui Song, Houxiong Fu, Hongyi Chen, Zhongwei Yan, Zibin Liu, Renyao Li, Anming Wang, Yongqiang Yang, Jia-Kuo Yu. Recrystallization induced by heat treatment regulates the anisotropic behavior of CoCrMo alloys fabricated by laser powder bed fusion[J]. Materials Futures. DOI: 10.1088/2752-5724/adb50a

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Journal

Materials Futures

DOI

10.1088/2752-5724/adb50a 

 Caribou case study offers a new model to manage species at risk

UCalgary researchers suggest a data-driven approach that identifies groups of at-risk caribou by movement patterns

University of Calgary

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Lead author Margaret Hughes, a PhD candidate with the Department of Biological Sciences in the Faculty of Science, works in the field in February 2025.

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Credit: Margaret Hughes/University of Calgary

Researchers at the University of Calgary are suggesting a more comprehensive approach for identifying at-risk wildlife populations — such as caribou — based on individual movement patterns.

The paper, published last month in the journal Biological Conservation, uses a long-term dataset of caribou wearing GPS collars across Western Canada. 

It identifies six distinct behavioural groups that would each deserve their own conservation actions.

“We took the approach of using behaviour to try to see if there are differences between individuals and groups that can be clustered into similarities,” says lead author Margaret Hughes, a PhD candidate with the Department of Biological Sciences in the Faculty of Science.

“You can infer when and where they’re going and try to infer why they are doing that based on what’s actually out across the landscape.”

The research determined whether the animals were migrating, how large of an area they were spending time in, and whether they were moving to different elevations.

Hughes says the data-driven approach showed slight differences from how caribou are managed in Western Canada.

Conservation managers often use genetic analysis to describe populations of at-risk caribou, but Hughes says the paper describes a more holistic approach that would also include behavioural analysis.

“It allows conservation managers to recognize ecologically meaningful variation within species, helping to maintain biodiversity and improve management strategies.”

Caribou, called reindeer in Europe, are members of the deer family.

“The species is iconic,” says Dr. Marco Musiani, PhD, a professor at the University of Bologna and an adjunct professor at UCalgary. “It is the most famous species affected by oil and gas and forestry in Canada and also climate change, and one of the most sensitive worldwide.”

Musiani, a supervisor on Hughes’ research, says the science is invaluable.

It suggests the novel approach holds promise for informing other conservation efforts.

“Our findings provide a framework that can be applied beyond caribou to other species at risk, helping to guide habitat protection, restoration, and even translocation strategies — areas that are currently the focus of significant investments,” explains Hughes.

As examples, she says it could inform where to put protected wildlife ecological corridors and conservation areas.

The paper involved other researchers from both the UCalgary Faculty of Veterinary Medicine and the Faculty of Science at UCalgary as well as the University of Bologna. It also included government researchers from the British Columbia Ministry of Water, Land and Resource Stewardship and the Canadian Wildlife Service.

The research covered a large area across the Rocky Mountains and boreal forest of Western Canada, particularly B.C. 

Hughes adds that the work wouldn’t have been possible without the help of the First Nations involved with the British Columbia Caribou Recovery Program.

“We acknowledge that this work took place throughout British Columbia, on the traditional territories of the First Nations where caribou currently exist.”

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Journal

Biological Conservation

DOI

10.1016/j.biocon.2024.110933 

Method of Research

Data/statistical analysis

Subject of Research

Animals

Article Title

Integrating movement behaviours for intra-specific conservation: The caribou case

 

Millions of children live with parents who have a substance use disorder

University of Michigan

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Nearly 17 million children and adolescents in the United States are estimated to live with a parent who has a substance use disorder, according to a study led by Texas State University, University of Michigan and Wayne State University.

 

The study found that alcohol use disorder was the leading contributor, affecting 12.8 million children. Cannabis use disorder was the second most prevalent, affecting 5 million children, while prescription opioid use disorder affects more than 1 million children. 

 

Of these categories, children may have parents who struggle with more than one substance use disorder. Parents with opioid use disorders also face higher risks of overdose, adding to the challenges these families face.

 

The research results are published in the Journal of Addiction Medicine.

 

"These findings remind children that they are not alone. The nearly 17 million children who are living with a parent with substance use disorder should convey a strong signal that it is time to focus more attention on children and families impacted by addiction," said co-author Sean Esteban McCabe, U-M professor of nursing and director of the Center for the Study of Drugs, Alcohol, Smoking and Health. 

 

"Our team is working on family-based programs to prevent the intergenerational transmission and vicious cycle of addiction."

 

The updated number marks an 81% increase from earlier estimates, largely due to updated diagnostic criteria in the Diagnostic and Statistical Manual of Mental Disorders. The transition from the fourth edition (DSM-IV) to the fifth edition (DSM-5) introduced revised definitions and criteria for certain conditions, leading to improved identification and more inclusive diagnostic guidelines. 

 

For example, the DSM-5 criteria and new approach to diagnosis offers a way to diagnose substance use disorder among parents who were symptomatic but undiagnosed "orphans" based on the older approach in the DSM-IV.

 

"The increase in the number of children who live with a parent with a substance use disorder was a great surprise, and it highlights the massive scale of services that these parents and children will need to be successful," said Ty Schepis, professor of psychology at Texas State and lead author of the study. "These children are at high risk for not just substance use issues of their own, but also mental health challenges and interactions with the legal and child welfare systems."

 

McCabe says the findings from the study are being disseminated across a number of different audiences as a way to reach more children and reduce stigma for kids who live with a parent with substance use disorders. It also indicates that the needs of children impacted by this living environment have increased, reinforcing the importance of work by organizations in the space, such as the initiative by Sesame Workshop. Sesame Workshop is the global nonprofit behind Sesame Street, which focuses on supporting young children and their circle of care impacted by parental addiction.

 

Funded by the National Institute on Drug Abuse and conducted in collaboration with U-M, Texas State, Wayne State and Vital Strategies, the study offers insight into the significant number of children and adolescents potentially exposed to heavy substance use in the home. The findings emphasize the importance of reaching this population through targeted interventions to improve their health and well-being.

 

The study also received funding from the U-M Office of the Vice President for Research and will serve as a key preliminary study for future projects that will make a positive difference for children and their families, McCabe says.

 

Research reported in this news release was supported by NIDA of the National Institutes of Health under award numbers R01DA043691 and R01DA031160.

 

Study: US Youth Exposed to Parental Substance Use Disorder in the Home: A Comparison of DSM-IV and DSM-5 Criteria (DOI: 10.1097/ADM.0000000000001469)

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Journal

Journal of Addiction Medicine

DOI

10.1097/ADM.0000000000001469 

Researchers develop enhanced method for wastewater surveillance of antibiotic resistance

Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign

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Illinois Civil and Environmental Engineering graduate student Yuqing Mao and Professor Helen Nguyen developed a new method for detecting antibiotic resistance genes in wastewater./ Helen Nguyen

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Credit: Yuqing Mao and Helen Nguyen

Antibiotic resistance is a global concern that threatens our ability to prevent and treat bacterial infections in humans and animals. To better monitor the emergence and spread of resistance, researchers at the Carl R. Woese Institute for Genomic Biology developed a CRISPR-enriched metagenomics method for the enhanced surveillance of antibiotic resistance genes, ARGs, in wastewater.

While antibiotics are powerful modern tools for combatting infections, bacteria change and adapt over time in response to antibiotic exposure, therefore decreasing effectiveness. Widespread overuse and misuse of antibiotics in the healthcare and food industries further accelerate this problem.

Beyond direct exposure to antibiotics, resistance is also passed between different bacteria through the transfer of small pieces of bacterial DNA called antibiotic resistance genes. There are over 5000 identified ARGs, and these genes can be found in clinical samples, as well as bodies of water, originating from hospitals, farms, and sewage systems.

“ARGs can reduce the life-saving power of drugs used to treat bacterial infections,” said Helen Nguyen (IGOH), a professor of civil and environmental engineering at the University of Illinois Urbana-Champaign. “Wastewater detection of ARGs with clinical significance allows public health authorities and physicians to anticipate what is circulating in communities.”

Wastewater contains numerous different ARGs mixed together with genetic material from various sources including humans, viruses, and bacteria. Because ARGs only make up a tiny percentage of the total DNA content, uncovering them in wastewater samples requires sensitive detection methods. The most common technique is quantitative polymerase chain reaction, qPCR. This method uses RNA guides called primers to identify the specific DNA sequences of known ARGs, which are then amplified for detection.

“qPCR is a sensitive method that many people in public health are well trained to do, but it requires primer design and validation which is very time consuming,” said Yuqing Mao, a doctoral student in civil and environmental engineering who was first author on the paper. “Since qPCR is used to pull out targeted gene sequences, all the other genetic material in the sample remains completely unknown.”

The second method, metagenomics, is not as sensitive as qPCR, but captures a more complete story of the genetic information contained in a sample. Metagenomics involves breaking all the sample DNA into millions of smaller fragments which are simultaneously sequenced using next generation sequencing technologies. Computational algorithms piece together the full DNA sequences for comparison against databases to determine their identities.

“ARGs make up less than one percent—probably even closer to 0.1 %—of DNA in the sample. Using standard metagenomics methods, 99.9 % of the DNA detected is not associated with ARGs,” Mao said.

To enrich the amount of ARG associated fragments in the samples, Mao, Nguyen, and their collaborator, Joanna Shisler, who is affiliated with the Department of Microbiology at Illinois, leveraged the CRISPR-Cas9 system—a highly effective tool for gene editing. The DNA is fragmented in random locations when using standard metagenomics methods, but incorporation of CRIPSR-Cas9 allows for targeted fragmentation within ARGs. By designing a pool of 6010 different guide RNAs that could specifically bind to DNA at different sites found in ARGs, the Cas9 protein could be directed to cut at these locations.

“Our new CRISPR method increases the abundance of ARG fragments in the sample, which increases their chances to be read and detected. CRISPR also has better potential for multiplexed assays than something like PCR because the molecular interaction is simple and straightforward for CRISPR,” Mao said.

Their new method lowered the detection limit of ARGs by an order of magnitude, from 10-4 to 10-5, compared to standard metagenomics and found 1189 more ARGs and 61 more ARG families which are low in abundance in wastewater samples.

As a sixth-year graduate student, Mao built this project from the ground up—overcoming scientific obstacles and learning many new techniques along the way. She said, “The first time I got the sequencing results, I never expected how much more sensitive it would be compared to the regular method—it detected many more ARGs than we thought it would. After finishing the project, I feel like I grew up.”

But while this work is wrapped up, Mao and Nguyen are already pursuing multiple new directions, including expanding the applications of their CRISPR-Cas9 metagenomic method to a broader range of environmental samples and using their results to guide the design of new qPCR primers.

The publication, “Enhanced detection for antibiotic resistance genes in wastewater samples using a CRISPR-enriched metagenomic method” can be found at https://doi.org/10.1016/j.watres.2024.123056 and was funded by the Water Research Foundation, NTU/U of I Joint Research and Innovation Seed Grants Program, and USEPA.

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Journal

Water Research

DOI

10.1016/j.watres.2024.123056 

Article Title

Enhanced detection for antibiotic resistance genes in wastewater samples using a CRISPR-enriched metagenomic method

 

Integrated framework for ecological security: A case study of the Daqing river basin

Higher Education Press

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Analytical framework for ecological security.

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Credit: Bo Nan et al.

In a recent study published in Engineering, researchers have developed an innovative analytical framework for ecological security assessment, prediction, and zoning management. Guided by the Social–Economic–Natural Complex Ecosystems (SENCE) theory, this framework aims to enhance ecological security for sustainable development.

The Daqing River Basin in the North China Plain was chosen as a case study due to its ecological significance and the increasing human-land conflicts. The research team established an assessment index system based on the pressure-state-response (PSR) model. For the pressure level, indicators like population density, nightlight index, and human interference index were selected. Net primary productivity, patch density, and Shannon diversity indices represented the state level, while the response level was indicated by the proportions of tertiary industries, nature reserve areas, and ecosystem service values.

The results showed a significant improvement in the overall ecological security of the Daqing River Basin from 2000 to 2020. It shifted from a “Moderate” level to a “Relatively Safe” level. Approximately 62% of the basin witnessed an improvement in ecological security levels during this period. However, spatial heterogeneity persisted. The northwestern and eastern regions had higher ecological security, while the central region, especially major urban areas in Beijing, Tianjin, and Hebei provinces, had lower ecological security.

Using the GM(1,1) model, the researchers predicted the ecological security trends. From 2025 to 2040, the overall ecological security of the basin is expected to continue improving and remain at the “Relatively Safe” level. But spatial heterogeneity will be further aggravated, as the ecological security in major urban areas will likely deteriorate.

To address these issues, the study proposed multi-scale ecological security management zones. At the regional scale, the basin was divided into western, central, and eastern zones. Each zone has its own regulatory strategies, such as soil and water conservation in the western zone, cultivated land protection in the central zone, and wetland protection in the eastern zone. At the county scale, 81 counties were classified into 5 distinct ecological management zones, including the mountain and wetland zone, plain zones, and urban zones, with tailored strategies for each.

This research provides a valuable reference for ecological governance in river basins and other regions facing similar human-land conflict issues. It also contributes to the theoretical development of ecological security research by integrating social, economic, and natural elements. Although the study has its limitations, such as not fully exploring the complex synergies and trade-offs between pressure, state, and response elements, it sets a solid foundation for future research in this field.

The paper “Ecological Security Assessment, Prediction, and Zoning Management: An Integrated Analytical Framework,” authored by Bo Nan, Yujia Zhai, Mengmeng Wang, Hongjie Wang, Baoshan Cui. Full text of the open access paper: https://doi.org/10.1016/j.eng.2024.11.032. For more information about the Engineering, follow us on X (https://twitter.com/EngineeringJrnl) & like us on Facebook (https://www.facebook.com/EngineeringJrnl).

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Journal

Engineering

DOI

10.1016/j.eng.2024.11.032 

Article Title

Ecological Security Assessment, Prediction, and Zoning Management: An Integrated Analytical Framework