A new thermoelectric material to convert waste heat to electricity

Researchers discover a new candidate, the mixed-semimetal MoSi2, that can be used to develop efficient thermoelectric devices

Tokyo University of Science

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MoSi2 demonstrates clear and large transverse thermopower, establishing itself as a promising candidate for developing efficient transverse thermoelectric devices.

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Credit: Associate Professor Ryuji Okazaki from Tokyo University of Science, Japan. https://www.nature.com/articles/s43246-025-01050-4

Thermoelectric conversion devices offer a promising route for sustainable heat-to-energy conversion. They are particularly attractive for recovering energy from waste heat, such as that produced by conventional fossil fuel-based engines, improving their overall energy efficiency. Around 20–50% of the input energy is lost as waste heat in industries. This could be used as source by thermoelectric conversion devices. These devices also have the potential to enable portable power generation, for example, to run small sensors in remote locations.

Currently, most thermoelectric devices rely on the longitudinal thermoelectric effect in which electricity is generated in the same direction as heat flow. Such devices generally consist of alternating layers of p- and n-type semiconductors connected in series. p- and n-type semiconductors generate electricity in opposite directions. When a temperature difference is applied across the device, the charge carriers in these materials move from the hot side to the cold side, generating a voltage. However, stacking many layers increases the electrical contact resistance at their interfaces, which leads to energy losses and limits overall efficiency.

Transverse thermoelectric (TTE) devices that generate voltage perpendicular to the direction of heat flow are a promising alternative. Importantly, TTE devices can be made from a single material, eliminating the need for multiple interfaces, significantly reducing contact resistance and improving overall efficiency. This also makes manufacturing simpler. However, materials that exhibit a strong TTE effect are rare.

In a recent study, a research team led by Associate Professor Ryuji Okazaki from the Department of Physics and Astronomy at Tokyo University of Science (TUS), Japan, demonstrated TTE behavior in the mixed-dimensional semimetal molybdenum disilicide (MoSi2). The team also included Ms. Hikari Manako, Mr. Shoya Ohsumi, and Assistant Professor Shogo Yoshida from TUS, as well as Assistant Professor Yoshiki J. Sato from Saitama University, Japan. Their findings were published in the journal Communications Materials on December 29, 2025.

“We wanted to explore new transverse thermoelectric materials. Recently, the presence of axis-dependent conduction polarity (ADCP) in a material has been recognized as an indicator for TTE generation ability,” explains Dr. Okazaki. “Mixed-metal conductors like MoSi2 are potential ADCP candidates, but their thermopower generation ability has not been thoroughly investigated.”

The researchers measured the transport properties of MoSi2 using both experiments and first-principles calculations. Specifically, they examined temperature dependence of resistivity and thermal conductivity, as well as longitudinal thermopower, along the material’s two crystallographic axes. Thermopower measurements demonstrated clear ADCP, which was further confirmed through Hall resistivity measurements.

To probe the origin of ADCP, the researchers examined the electronic structure of MoSi2 using first-principles calculations. They found that ADCP originates from a mixed-dimensional Fermi surface structure, consisting of two Fermi surfaces with opposite polarities. The Fermi surface is essentially a boundary that separates filled and empty electronic states of a solid material. The shape of this surface, therefore, strongly determines the electronic and transport properties of the material.

Next, the researchers directly measured transverse thermopower of MoSi2 by applying a temperature difference at a 45-degree angle to one of its crystallographic axes. The results showed clear and substantial transverse thermopower signal. Notably, the magnitude of this signal was larger than that observed for tungsten disilicide (WSi2), another ADCP material examined previously by the team, mainly due to differences in how its electrons are distributed. Moreover, the transverse thermopower of MoSi2 was comparable to that of anomalous Nernst materials, which are magnetic materials well known for their strong TTE effects.

“These findings establish MoSi2 as an ideal material for TTE applications, particularly in the low-temperature range, thereby expanding the list of viable candidates,” remarks Dr. Okazaki. “Moreover, both MoSi2 and WSi2 show that mixed-dimensional Fermi surfaces are important for the emergence of ADCP and therefore transverse thermopower.”

By utilizing thin film of MoSi2 as an ideal material for TTE applications, large heat source area could be covered to produce voltage. Overall, this study represents a new direction for finding TTE materials, paving the way for efficient waste heat recovery systems for a greener future.

 

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Reference
DOI: 10.1038/s43246-025-01050-4  

About The Tokyo University of Science
Tokyo University of Science (TUS) is a well-known and respected university, and the largest science-specialized private research university in Japan, with four campuses in central Tokyo and its suburbs and in Hokkaido. Established in 1881, the university has continually contributed to Japan's development in science through inculcating the love for science in researchers, technicians, and educators.

With a mission of “Creating science and technology for the harmonious development of nature, human beings, and society," TUS has undertaken a wide range of research from basic to applied science. TUS has embraced a multidisciplinary approach to research and undertaken intensive study in some of today's most vital fields. TUS is a meritocracy where the best in science is recognized and nurtured. It is the only private university in Japan that has produced a Nobel Prize winner and the only private university in Asia to produce Nobel Prize winners within the natural sciences field.

Website: https://www.tus.ac.jp/en/mediarelations/

About Associate Professor Ryuji Okazaki from Tokyo University of Science
Dr. Ryuji Okazaki is currently an Associate Professor at the Department of Physics and Astronomy at Tokyo University of Science, Japan. He received his Ph.D. degree from Kyoto University, Japan. He has published over 150 articles that have received over 3,300 citations, including a feature article in the journal Applied Physics Letters. He is the recipient of the Papers of Editors' Choice by JPSJ in 2017 from The Physical Society of Japan and the 2012 Award for Encouragement of Research in Materials Science. His research is focused on correlated electron systems and condensed matter physics.

Laboratory website 
Official TUS website 

 

Funding information
This work was partly supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI via Grants No. 22K20360, No. 22H01166, and No. 24K06945, and the Research Foundation for the Electrotechnology of Chubu (REFEC) via Grant No. R-04102.

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Journal

Communications Materials

DOI

10.1038/s43246-025-01050-4 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Axis-Dependent Conduction Polarity and Transverse Thermoelectric Conversion in the Mixed-dimensional Semimetal MoSi2

 

Restricting mothers' migration: New evidence on children’s health and education

A policy restricting mothers' overseas migration in Sri Lanka improved children's health and education

Sophia University

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Using national household survey data and a real-world policy change in Sri Lanka, this study shows how restricting mothers’ international migration during early childhood is associated with improved health and educational outcomes for children, without reducing household income.

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Credit: Associate Professor Takuya Hasebe from Sophia University, Japan

International labor migration plays a vital role in supporting families across low- and middle-income countries, often providing a critical source of income for families back home. However, when mothers migrate abroad for work, young children may be left without steady parental care during important developmental stages. While this concern is widely discussed, there has been limited real-world evidence showing how policies that restrict maternal migration affect children’s outcomes.

 

A new study made available online on December 13, 2025, and published in Volume 200 of the World Development journal on April 1, 2026, examines this question by analyzing a migration policy introduced in Sri Lanka in 2013. The policy restricted mothers with children under 5 years of age from migrating overseas for work. By comparing families affected by the policy with those who were not, the researchers assessed its impact on children’s health, education, and household income. The study was led by Associate Professor Takuya Hasebe from Sophia University, Japan, with co-authors Yuma Noritomo from Cornell University, USA, and Bilesha Weeraratne from the Institute of Policy Studies, Sri Lanka.

 

“This study assessed a policy that was actually implemented in Sri Lanka,” says Dr. Hasebe. “We hope that its findings will contribute to ongoing discussions on migration policy in Sri Lanka and other countries.”

 

To inspect the policy’s effects, the researchers used data from Sri Lanka’s Household Income and Expenditure Survey collected between 2009 and 2016. This nationally conducted survey includes detailed information on family structure, income sources, education, and health. The team compared households affected by the policy with similar households that were not affected, both before and after the policy was introduced. This approach allowed them to isolate the effects of the migration restriction from broader economic or social trends.

 

The study focused on households with children between the ages of 2 and 10 years. Key outcomes included children’s hospital admissions and illness-related inpatient stays, as well as educational indicators, such as grade repetition, which refers to a child repeating the same school year.

 

The analysis showed that the policy led to fewer mothers migrating abroad for work and increased the likelihood that mothers remained at home with their young children. This change was associated with clear benefits for children’s well-being. Children in affected households experienced fewer hospital admissions and fewer illness-related inpatient stays, indicating improvements in overall health. Educational outcomes also improved, particularly for older siblings, who were less likely to repeat a school grade.

 

“These improvements can be understood as investments in human capital,” explains Dr.  Hasebe. “The effects are not merely temporary; the accumulation of human capital is likely to have lasting positive impacts on children’s future outcomes.”

 

One common concern about restricting international migration is the potential loss of income from overseas remittances. However, the study found no overall decline in household income. While international payments decreased, this loss was largely offset by increased domestic income support, such as earnings from within the country or transfers from other household members.

 

The findings suggest that policies aimed at keeping mothers with young children at home may offer important social benefits. At the same time, the researchers caution that migration policies are complex and can have multiple effects beyond those captured in this analysis.

 

“Our analysis captures only one aspect of the policy,” Dr. Hasebe notes. “A more comprehensive, multi-dimensional approach will be an important direction for future research.”

 

Overall, by providing rare empirical evidence from a real-world policy intervention, the study adds an important perspective to global debates on migration, family welfare, and child development. It highlights how decisions about labor mobility can shape children’s lives in lasting ways—well beyond short-term economic considerations.

 

Reference

Title of original paper:	Restricting mothers’ international migration and human capital investment
Journal	World Development
DOI:	10.1016/j.worlddev.2025.107284
Authors	Takuya Hasebe1, Yuma Noritomo2, and Bilesha Weeraratne3
Affiliations:	1Sophia Institute for Human Security and Faculty of Liberal Arts, Sophia University, Tokyo, Japan 2Charles H. Dyson School of Applied Economics and Management, Cornell University, USA 3Institute of Policy Studies of Sri Lanka, Colombo, Sri Lanka

 

About Sophia University

Established as a private Jesuit affiliated university in 1913, Sophia University is one of the most prestigious universities located in the heart of Tokyo, Japan.  Imparting education through 29 departments in 9 faculties and 25 majors in 10 graduate schools, Sophia hosts more than 13,000 students from around the world.

Conceived with the spirit of “For Others, With Others,” Sophia University truly values internationality and neighborliness, and believes in education and research that go beyond national, linguistic, and academic boundaries. Sophia emphasizes on the need for multidisciplinary and fusion research to find solutions for the most pressing global issues like climate change, poverty, conflict, and violence. Over the course of the last century, Sophia has made dedicated efforts to hone future-ready graduates who can contribute their talents and learnings for the benefit of others, and pave the way for a sustainable future while “Bringing the World Together.”

Website: https://www.sophia.ac.jp/eng/

 

About Associate Professor Takuya Hasebe from Sophia University

Associate Professor Takuya Hasebe is an economist at the Sophia Institute for Human Security and the Faculty of Liberal Arts, Sophia University, Japan. He holds a Ph.D. in Economics from the City University of New York and a Bachelor of Arts from Rutgers University. His research focuses on labor economics, health economics, and econometrics, applying statistical methods to real-world policy issues such as labor supply and health disparities. Dr. Hasebe has over a decade of research experience and has published more than 10 journal articles.

---

Journal

World Development

DOI

10.1016/j.worlddev.2025.107284 

Method of Research

Observational study

Subject of Research

People

Article Title

Restricting mothers’ international migration and human capital investment

Article Publication Date

1-Apr-2026

 

CT scans unwrap secrets of ancient Egyptian life

Keck Medicine of USC scans and analyzes two Egyptian mummies to reveal new details about their lifespans, health and life experiences

University of Southern California - Health Sciences

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Keck Medicine of USC scans two ancient Egyptian mummies using innovative computed tomography (CT) scanners. Summer Decker, PhD, (right), 3D imaging lead for Keck Medicine and director of the USC Center for Innovation in Medical Visualization, and Jonathan Ford, PhD, (left) associate director of the center, examine the mummies, part of “Mummies of the World: The Exhibition” at the California Science Center.

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Credit: Ricardo Carrasco III

Photos and b-roll package available for download here.

LOS ANGELES — Keck Medicine of USC radiologists use computed tomography (CT) scanners to diagnose and treat patients’ diseases and injuries.  

Recently, however, this advanced technology was put to a far more novel use: examining the bodies of two ancient Egyptian mummies. 

Radiologists conducted full-body CT scans of two Egyptian priests, Nes-Min, circa 330 BCE, and Nes-Hor, circa 190 BCE, whose bodies had been preserved for more than 2,200 years.  

The mummies, along with 3D digital models and 3D prints of select parts of their bodies, will be on display at “Mummies of the World: The Exhibition,” an upcoming exhibit at the California Science Center opening Feb. 7.  

Each mummy was scanned inside the bottom half of its sarcophagus, which weighed approximately 200 pounds each. The mummies were wrapped in linen shrouds, blackened with age. The older mummy, Nes-Min, was draped in a garment of heavily beaded net over his torso and wore several strands of colorful beads.  

A state-of-the-art, 320 slice CT scanner revealed small details of their bodies that humanized the men, including facial features such as eyelids and their lower lips. The images also held clues about their health, life experiences and lifespans that resonate with people today.  

Scans reveal healed injuries, dental issues and other modern-day ailments  

Analysis of the scans showed that the elder of the mummies, Nes-Min, probably suffered from an aching lower back like many modern humans. His spine showed a collapsed lumbar or lower back vertebrae likely due to natural aging and wear and tear.  

He was buried with several artifacts, representing several scarab beetles and a fish.  

Nes-Hor’s scan revealed dental issues and a severely deteriorated hip, and that he was older at the time of death than Nes-Min.  

"These scans provide a treasure trove of information made possible by Keck Medicine’s access to the latest in high-level scanning, coupled with the team’s expertise,” said Summer Decker, PhD, who leads 3D imaging for Keck Medicine and serves as director of the USC Center for Innovation in Medical Visualization with the Keck School of Medicine of USC.  

“These mummies were scanned previously, but due to advancements in scanning technology, the results are much more detailed and extensive than ever before,” said Decker, who oversaw the mummy scans and visualization analysis. “The high-resolution images have revealed things that were previously unknown and helped create a picture of what their lives were like.” 

After scanning the mummies, Decker and her colleague, Jonathan Ford, PhD, used the scans to create 3D digital models of the men. They also printed out life-size reproductions of the men’s spines, skulls and hips, as well as artifacts found with Nes-Min, using medical-grade 3D printers.  

“Mummies have long been a mystery. Seeing beneath the surface to reveal the specific lived experience of individuals is incredibly exciting,” said anthropologist Diane Perlov, PhD, senior vice president for special projects at the California Science Center. “This modern scientific technology offers us a powerful window into the world of ancient people and past civilizations that might otherwise be lost.” 

Keck Medicine’s 3D technology brings organs to life  

Keck Medicine’s 3D visualization and printing technologies used on the mummies allow for surgeons to turn medical imaging, such as a CT or MRI scan, into physical reproductions of a patient’s liver, heart, pelvis or other structure.  

The scans first create hundreds of detailed 3D cross-sectional images (or “slices”), then 3D visualization experts digitally “stack” the images together to form 3D digital models. These models can then be analyzed, measured or used to print on high-resolution medical-grade 3D printers, meaning that the prints can be used in surgery and are safe to touch and potentially be implanted in a patient.  

Surgeons then use these prints to better visualize and understand a patient’s complex medical condition or practice the best surgical solution before entering the operating room. 

“Through 3D visualization, modeling and printing, clinicians like surgeons can accurately measure hard-to-detect tumors, examine the intricate structure of a patient’s heart or liver or determine how best to repair a shoulder or hip,” said Decker. “They walk into the operating room with a much better idea of what they are facing and how they will approach surgery. With these advanced technologies, we can create custom treatments and solutions for our patients, which may lead to improved outcomes.”  

Patients may also benefit from holding a replica of their own organ in their hand, Decker continued. “They gain a new understanding of what their condition is and how it will be treated,” she said.  

Keck Medicine has access to almost two dozen 3D printers housed in the USC Center for Innovation in Medical Visualization. 

About the exhibit  

“Mummies of the World: The Exhibition” first debuted at the California Science Center in 2010. After touring the globe, the exhibition returns to Los Angeles for its closing venue with a new selection of mummies never seen before in Los Angeles.  

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For more information about Keck Medicine of USC, please visit news.KeckMedicine.org. 

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