UVA research team detects additive manufacturing defects in real-time

Machine learning approach helps hit 100% prediction rate

Peer-Reviewed Publication

UNIVERSITY OF VIRGINIA SCHOOL OF ENGINEERING AND APPLIED SCIENCE

PrintEmail App

 

IMAGE: UVA ASSOCIATE PROFESSOR TAO SUN IN HIS LAB AT THE UNIVERSITY OF VIRGINIA. view more 

CREDIT: PHOTO BY TOM COGILL FOR UVA ENGINEERING

A research team led by Tao Sun, associate professor of materials science and engineering at the University of Virginia, has made new discoveries that can expand additive manufacturing in aerospace and other industries that rely on strong metal parts.

Their peer-reviewed paper was published Jan. 6, 2023, in Science Magazine: “Machine learning aided real-time detection of keyhole pore generation in laser powder bed fusion.” It addresses the issue of detecting the formation of keyhole pores, one of the major defects in a common additive manufacturing technique called laser powder bed fusion, or LPBF.

Introduced in the 1990s, LPBF uses metal powder and lasers to 3-D print metal parts. But porosity defects remain a challenge for fatigue-sensitive applications like aircraft wings. Some porosity is associated with deep and narrow vapor depressions which are the keyholes.

The formation and size of the keyhole is a function of laser power and scanning velocity, as well as the materials’ capacity to absorb laser energy. If the keyhole walls are stable, it enhances the surrounding material’s laser absorption and improves laser manufacturing efficiency. If, however, the walls are wobbly or collapse, the material solidifies around the keyhole, trapping the air pocket inside the newly formed layer of material. This makes the material more brittle and more likely to crack under environmental stress.

Sun and his team, including materials science and engineering professor Anthony Rollett from Carnegie Mellon University and mechanical engineering professor Lianyi Chen from the University of Wisconsin-Madison, developed an approach to detect the exact moment when a keyhole pore forms during the printing process.

“By integrating operando synchrotron x-ray imaging, near-infrared imaging, and machine learning, our approach can capture the unique thermal signature associated with keyhole pore generation with sub-millisecond temporal resolution and 100% prediction rate,” Sun said.

In developing their real-time keyhole detection method, the researchers also advanced the way a state-of-the-art tool — operando synchrotron x-ray imaging — can be used. Utilizing machine learning, they additionally discovered two modes of keyhole oscillation.

"Our findings not only advance additive manufacturing research, but they can also practically serve to expand the commercial use of LPBF for metal parts manufacturing," said Rollett. Rollett is also the co-director of the NextManufacturing Center at CMU. 

“Porosity in metal parts remains a major hurdle for wider adoption of LPBF technique in some industries. Keyhole porosity is the most challenging defect type when it comes to real-time detection using lab-scale sensors because it occurs stochastically beneath the surface,” Sun said. “Our approach provides a viable solution for high-fidelity, high-resolution detection of keyhole pore generation that can be readily applied in many additive manufacturing scenarios.”

  

A sample of additive metal manufacturing produced using a machine learning approach in combination with operando synchrotron x-ray imaging.

CREDIT

Photo by Tom Cogill for UVA Engineering

About UVA Engineering: As part of the top-ranked, comprehensive University of Virginia, UVA Engineering is one of the nation’s oldest and most respected engineering schools. Our mission is to make the world a better place by creating and disseminating knowledge and by preparing future engineering leaders. Outstanding students and faculty from around the world choose UVA Engineering because of our growing and internationally recognized education and research programs. UVA is the No. 1 public engineering school in the country for the percentage of women graduates, among schools with at least 75 degree earners; among the top engineering schools in the United States for the four-year graduation rate of undergraduate students; and among the top-growing public engineering schools in the country for the rate of Ph.D. enrollment growth. Our research program has grown by 95% since 2016. Learn more at engineering.virginia.edu.

UVA materials science and engineering postdoctoral fellow Zhongshu Ren, left, and Tao Sun display the results of their research. Ren is the first author of the Science Magazine journal article.

CREDIT

Photo by Tom Cogill for UVA Engineering

JOURNAL

Science

DOI

10.1126/science.add4667 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Machine learning–aided real-time detection of keyhole pore generation in laser powder bed fusion

 

High-speed visible light communication based on micro-LED: A technology with wide applications in next generation communication

Peer-Reviewed Publication

COMPUSCRIPT LTD

 

IMAGE: FIG. 1 | SUMMARY OF THE REVIEW, WHICH INCLUDES MODULATION BANDWIDTH IMPROVEMENT, WHITE LIGHT EMITTING DIODES (WLED)-BASED VLC, ΜLED DETECTOR AND APPLICATIONS OF VLC TOWARDS 6G. view more 

CREDIT: OES

A new publication from Opto-Electronic Science; DOI   10.29026/oes.2022.220020  considers high-speed visible light communication based on micro-LED.

 

The evolution of next-generation cellular networks is aimed at creating faster, more reliable solutions. Both the next-generation 6G network and the metaverse require high transmission speeds. Visible light communication (VLC) is deemed an important ancillary technology to wireless communication. Light-emitting diode (LED) solid-state lighting technology offers low power consumption and cost, small size, and a long operational lifetime. Moreover, it is environmentally friendly. These advantages contributed to the explosive growth of the LED-lighting market. Notably, the visible-light band with a spectral range between 380 and 780 nm is not licensed like radio frequencies and can be used without authorization. Hence, LED-based visible light communication (VLC) technology has attracted research attention worldwide, and VLC technology has rapidly developed in the past decade.

The flickering of LEDs cannot be identified by the naked eye, owing to the high frequency of the signal in the VLC system. Thus, by adding relatively inexpensive front-end components, VLC can be easily implemented in existing lighting infrastructures to achieve data communications with speeds in the Gbps range. Furthermore, compared with the considerable co-channel interference of wireless RF communication, the propagation of visible light is not perturbed by electromagnetic waves, i.e., the electromagnetic interference phenomenon does not occur. Therefore, VLC offers unique advantages in hospitals, airports, nuclear power plants, underground mines, substations, and other scenarios that are sensitive to electromagnetic interference. Owing to high modulation bandwidths of micro light-emitting diodes (μLEDs), they are ideal light sources for high-speed VLC. Although μLEDs are now widely used in VLC, few studies have provided general descriptions of μLED-based VLC systems from devices to applications.

The authors of this article present an overview of μLEDs for VLC. Methods to improve the modulation bandwidth are discussed in terms of epitaxy optimization, crystal orientation, and active region structure. Moreover, photoluminescent white LEDs based on phosphor or quantum-dot color conversion and μLED-based detectors for VLC are introduced. Finally, the latest high-speed VLC applications and the application prospects of VLC in 6G are introduced.

As the most common type of μLEDs, structural optimization of c-plane μLED devices has been reported and the improvement of the modulation bandwidth has mainly focused on enhancing the carrier recombination process. The specific methods include the formation of metal contacts with low contact resistance by thermal annealing, the growth of ultra-thin QW devices, etc., which can significantly improve the modulation bandwidth of μLED devices. Furthermore, C-plane LEDs are affected by a strong quantum confinement Stark effect (QCSE), which limits the modulation bandwidth. One approach to overcome the QCSE is to fabricate nonpolar or semipolar structures. As shown in Fig. 2 (a), the modulation bandwidth of μLEDs with different crystal orientations is shown. The bandwidth of μLEDs grown on the nonpolar faces is the highest, followed by the semi-polar plane and c-plane. Therefore, manufacturing non-polar or semi-polar μLED is also a method to improve the modulation bandwidth.

Due to their low power consumption, high brightness, high resolution and colour saturation, μLEDs are advantageous for display and lighting applications. Therefore, white-light VLC systems based on μLEDs can achieve both illumination and display functions in addition to high-speed data transmission, which has greater application prospects. The authors of this article have compiled the latest advances in μLED-based white-light VLC systems in recent years to demonstrate that these kind of systems are expected to become an important part of next-generation communication and illumination technologies.

As the research on μLED devices expands, the μLED-based high-speed VLC is garnering increasing interest. This review summarizes the advantages and challenges of μLEDs in VLC systems. Methods to improve the modulation bandwidth of μLEDs were introduced. In addition to conventional c-polar epitaxial structure optimization and semi/nonpolar GaN epitaxial growth, μLEDs using microstructures or InGaN QDs as active regions can also improve the radiative recombination rate. μLEDs are considered bright solid-state lighting sources compared with different classes of WLEDs for VLC. Similarly, μLEDs can also be used as detectors in VLC systems. Finally, the prospects of VLC in 6G and the latest high-speed VLC applications were introduced. Given the high-speed transmission advantages, μLED-based VLC is expected to become an ancillary technology for 6G and cooperate with other communication technology to benefit our daily lives. This work provides new ideas for the device design of high-bandwidth μLEDs, reveals more potential uses of μLED-based high-speed VLC systems, and provides a new technical path for the promotion of VLC in next-generation communication technologies.

 

Fig. 2 | Modulation bandwidth optimization of μLEDs based on c-plane epitaxial structure

Fig. 3 | Modulation bandwidth optimization of μLEDs by nonpolar and semipolar plane growth

CREDIT

OES

Keywords: visible light communication / μLEDs / modulation bandwidth / detector / 6G

 

# # # # # #

 

The Solid-State Lighting and Display Laboratory (SSLAB) in Xiamen University (XMU), founded in 2006, currently consists of 16 research fellows. Under the supervision of Prof. Rong Zhang (President of XMU) and Prof. Zhong Chen (Dean of School of Electronic Science and Engineering), SSLAB keeps exploring new areas such as measuring methodologies and full-color solution of micro-LEDs, visible light communications, and UVC LED disinfections. Located in the west of the Taiwan Straits, SSLAB enjoys the privilege of the collaboration with colleagues in Taiwan, such as the research team of Prof. Hao-Chung Kuo in NCTU. Moreover, SSLAB has published 3 books, more than 200 journal papers and 40 patents, and hosted many research funds granted by the NSFC, ministry of science and technology, etc.

 

# # # # # #

Opto-Electronic Science (OES) is a peer-reviewed, open access, interdisciplinary and international journal published by The Institute of Optics and Electronics, Chinese Academy of Sciences as a sister journal of Opto-Electronic Advances (OEA, IF=9.682). OES is dedicated to providing a professional platform to promote academic exchange and accelerate innovation. OES publishes articles, reviews, and letters of the fundamental breakthroughs in basic science of optics and optoelectronics.

# # # # # #

 

More information: https://www.oejournal.org/oes

Editorial Board: https://www.oejournal.org/oes/editorialboard/list

OES is available on OE journals (https://www.oejournal.org/oes/archive)

Submission of OES may be made using ScholarOne (https://mc03.manuscriptcentral.com/oes)

CN 51-1800/O4

ISSN 2097-0382

Contact Us: oes@ioe.ac.cn

Twitter: @OptoElectronAdv (https://twitter.com/OptoElectronAdv?lang=en)

WeChat: OE_Journal

 

# # # # # #

 

Article reference Lu TW, Lin XS, Guo QA, Tu CC, Liu SB et al. High-speed visible light communication based on micro-LED: A technology with wide applications in next generation communication. Opto-Electron Sci 1, 220020 (2022). doi: 10.29026/oes.2022.220020 

 

# # # # # #

---

DOI

10.29026/oes.2022.220020 

Supersonic science: Case Western Reserve University to conduct 9,000 mph ballistics tests into water tank

Researchers expect anything from vaporization to creating ice or light in project funded by U.S. Navy, Air Force

Grant and Award Announcement

CASE WESTERN RESERVE UNIVERSITY

 

IMAGE: AN IMAGE OF A PROJECTILE AT THE POINT OF IMPACT WITH WATER (AT ONLY 15 MPH) FROM EARLIER TESTS. view more 

CREDIT: CWRU/BRYAN SCHMID

 

CLEVELAND–Sometime this coming summer, on the second floor of a research building on the Case Western Reserve University campus, scientists hope to record something the world has never witnessed: The moment of impact when an 18-millimeter-diameter projectile hits a wall of water at 9,000 miles per hour.

 

What will occur in that instant and in the subsequent milliseconds—expected to be captured in detail by high-speed cameras—is a tantalizing mix of “knowns, unknowns and what-if’s,” according to the project’s lead researcher.

 

“Even today in 2022, the scientific community actually doesn’t know what exactly will happen to the water in that type of event,” said Bryan Schmidt, an assistant professor of mechanical and aerospace engineering. “But there's reason to believe it might do some really strange things—from creating ice to creating light.”

 

Schmidt said his experiments will be at a speed nearly twice as fast as anything in the published research and with far better recording equipment than when military research was first conducted in the 1940s to study what the shock waves from underwater explosions might do to boats or submarines.

 

“We’re doing something no one else is doing right now,” he said. “Our experiments are also timely and could have a far greater impact for our country.”

 

U.S. defense applications

 

That’s because the proposed scientific experiments at Case Western Reserve also offer likely applications for national defense. 

  

“What we learn will be very important to this country for being able to accurately predict things like the damage potential for ships close to high-yield underwater explosions, the flight of hypersonic vehicles or missiles through mist, rain, or sea spray, and damage potential of hypersonic projectiles,” Schmidt said.

 

The research by Schmidt and his collaborators is supported by a pair of recent defense grants, totaling about $1 million: $750,000 from the Office of Naval Research and $300,000 from the Air Force Office of Scientific Research Instrumentation Program.

 

Researchers at the U.S. Naval Surface Warfare Center, Carderock Division in Bethesda, Maryland, will also perform computer simulations to complement the experiments at Case Western Reserve.

 

Hypersonic weaponry has also been in the news recently. The U.S. has launched test rockets, while Russia and China claim they’ve already used them in conflicts.

 

Hypersonic weapons travel at speeds greater than Mach 5, or about 4,000 mph, making them hard to detect and intercept. The missiles can also maneuver and vary altitude, allowing them to evade missile-defense systems.

 

Massive energy release, different possibilities

 

To conduct the experiments, Schmidt will use a 40-foot-long piece of equipment known as a “two-stage light gas gun” to propel an 18-millimeter projectile into an 8-foot deep tank of water.  The devices, often used by scientists to propel objects to simulate meteorites hitting the atmosphere, have two different stages of propulsion, resulting in faster launch speeds.

 

And while the impact is dramatic, to the viewer in the room, it will be too fast to see with the naked eye—and will “result in a big splash of water caught by a kiddie pool,” Schmidt said.

 

The real excitement and payoff will come when he views the video and photographs.

 

Schmidt will chronicle the impact with a high-speed camera that can capture up to 200 million frames per second. For comparison, the human eye sees the equivalent of 30 frames per second; a smart phone, about 300 frames per second.

 

The possibilities include:

 

• Ice formation: One prediction from the 1950s was that water hit by a supersonic projectile could form “exotic ice,” Schmidt said. Exotic ice is any formation beyond the six-sided ice most common on Earth and found mostly in space or the Earth’s mantle.

 

• Cavitation: The formation of vapor bubbles within a liquid accelerated to high velocities, such as when hit by a high-speed projectile. “I’m dead certain we’ll see cavitation behind the projectile,” Schmidt said.

 

• Sonoluminescence: The creation of light when liquid collapses quickly as the result of a sound wave. The bubbles may also reach extremely high temperatures and pressures for brief periods of time, a phenomenon that has intrigued researchers for decades for its potential to possibly lead to a waste-free energy source.

 

The speed of sound in the air is about 767 mph, but the speed of sound in water is closer to 3,500 mph—more than four times faster.

 

That means Schmidt and his team will do their experiments at speeds that are hypersonic in the air (more than five times the speed of sound), but technically supersonic relative to the speed of sound in water.

 

 

                                    ###

 

Case Western Reserve University is one of the country's leading private research institutions. Located in Cleveland, we offer a unique combination of forward-thinking educational opportunities in an inspiring cultural setting. Our leading-edge faculty engage in teaching and research in a collaborative, hands-on environment. Our nationally recognized programs include arts and sciences, dental medicine, engineering, law, management, medicine, nursing and social work. About 5,800 undergraduate and 6,300 graduate students comprise our student body. Visit case.edu to see how Case Western Reserve thinks beyond the possible.

 

New laser lays groundwork for next generation ethernet technology

Researchers report 200 Gb/s data transmission over an unprecedented 10 kilometers

Meeting Announcement

OPTICA

 

IMAGE: SCHEMATIC VIEW OF LE-TYPE-EA-DFB LASER view more 

CREDIT: LUMENTUM JAPAN

Scientists from Japan have developed a new type of distributed feedback (DFB) laser and showed that it can be used to transmit data at speeds of 200 Gb/s over a record distance of 10 kilometers. This research could help advance network technology that would allow internet data centers to handle unprecedented levels of data.

Kazuki Nishimura an Optical Engineer, Datacom Business Unit with Lumentum Japan will present the new research at the Optical Fiber Communication Conference (OFC), taking place 05 – 09 March 2023 in San Diego, California, USA.

“The research contributes to the development of next generation data centers for 800G and 1.6T ethernet. Particularly, the new technology suggests electro-absorption modulators with integrated distributed feedback (EA-DFB) lasers can work even 10-km transmission using conventional PAM4 (pulse amplitude modulation) technology, which is defined as a simple intensity-modulation direct-detection (IM/DD) scheme,” said Nishimura.

As communication traffic continues to increase, there is a growing focus on implementing next generation ethernet technology, such as 800G and 1.6T ethernet, to help data centers meet growing demands. Although the same PAM4 technology used for 2-km transmission in today’s 400G ethernet is being considered for 800G, new technology is needed to achieve data transmission over longer distances for interconnections between data center regions or campuses.

In the new work, the researchers developed a lumped electrode electroabsorption (EA) modulator DFB laser to achieve longer distances. They first used the new laser to demonstrate 5-km transmission of 225-Gb/s PAM4 using the coarse wavelength division multiplexing (CWDM) wavelength band under 50°C operation. They also used the laser for 10-km transmission of 225-Gb/s PAM4 at 1293.5 nm. This wavelength exhibits less chromatic dispersion than the wavelength range assigned to CWDM, the technology typically used to simultaneously send multiple optical signals over an optical fiber. Chromatic dispersion can cause degradation in the optical signal and is more problematic for longer transmission distances.

For all the experiments, the new laser exhibited low transmitter and dispersion eye closure quaternary (TDECQ) values, indicating solid transmitter performance. The researchers say that their results demonstrate the potential of the lumped electrode EA-DFB laser as a light source for 800G ethernet technology, including 10-km applications. It could also be useful for longer reach 5-km CWDM4 applications.

“The traffic in data centers is significantly growing annually as high-resolution video-streaming services, such as 4k and cloud applications. These results show our EA-DFBs are a promising optical light source to realize the upcoming 800GbE applications,” said Nishimura.

Registration Information

Registration is free for credentialed media and analysts. The registration includes in-person and virtual attendance. Digital assets are available for credentialed media. Learn more: OFC media room.

About OFC

The 2023 Optical Fiber Communication Conference (OFC) is the premier conference and exhibition for optical communications and networking professionals. For more than 40 years, OFC has drawn attendees from all corners of the globe to meet and greet, teach and learn, make connections and move business forward. OFC includes dynamic business programming, an exhibition of global companies and high impact peer-reviewed research that, combined, showcase the trends and pulse of the entire optical networking and communications industry. OFC is managed by Optica (formerly OSA) and co-sponsored by IEEE Communications Society (IEEE/ComSoc), IEEE Photonics Society and Optica. OFC 2023, a hybrid conference, will take place 05 – 09 March 2023 in San Diego, California. Follow @OFCConference, learn more at OFC Community LinkedIn, and watch highlights on OFC YouTube.

Aware or not aware: You are affected by food cues either way

Osaka Metropolitan University scientists show that unconscious neural processes may play an important role in controlling eating behavior

Peer-Reviewed Publication

OSAKA METROPOLITAN UNIVERSITY

 

IMAGE: SCIENTISTS SHOW THAT IN THE INFERIOR FRONTAL GYRUS, NEURAL ACTIVITY DIFFERS IN RESPONSE TO FOOD IMAGES, DEPENDING ON WHETHER THOSE IMAGES ARE PRESENTED CONSCIOUSLY OR UNCONSCIOUSLY. THIS DIFFERENCE WAS ASSOCIATED WITH SCORES ON EATING BEHAVIORS SUCH AS EMOTIONAL EATING AND RESTRAINED EATING. view more 

CREDIT: OSAKA METROPOLITAN UNIVERSITY

Osaka, Japan – Controlling your food intake can be even more difficult than you think. Osaka Metropolitan University scientists show that visual food cues can affect your eating behavior even when you are not aware of them. Their findings were published in PLOS ONE.

Obesity is one of the major pathological conditions that constitute lifestyle-related diseases and is known to be associated with myocardial infarction, stroke, and carcinogenesis. Approaches to regulate eating behavior are widely used in an effort to control obesity, but it has been reported that about half of those who receive dietary guidance return to their original weight within five years.

To explain the limited effectiveness of such guidance, one hypothesis suggests that not only conscious neural processes, which the dietary guidance targets, but also unconscious neural processes play an important role in controlling eating behavior. However, there were no studies directly examining the validity of this hypothesis at the level of neural activity.

The research team led by Professor Takahiro Yoshikawa from the Graduate School of Medicine at Osaka Metropolitan University has revealed that in the inferior frontal gyrus, a region of the brain’s frontal lobe that controls eating behavior, neural activity differs in response to visual food stimuli, or food images, depending on whether those images are presented consciously or unconsciously. Using a questionnaire to assess the study participants, the team found that this difference was associated with their scores on eating behaviors, including emotional eating and cognitive restraint of food intake. These results indicate that eating behavior cannot be understood without taking into account both unconscious and conscious neural processes.

“If we can learn more in future research about how eating behavior is controlled by unconscious neural processes, we can combine that understanding with our current knowledge of conscious neural processes to potentially develop more effective methods for regulating eating behavior,” stated Professor Yoshikawa.

 

###

About OMU

Osaka Metropolitan University is a new public university established in April 2022, formed by a merger between Osaka City University and Osaka Prefecture University. For more research news, visit https://www.omu.ac.jp/en/info/research-news/ or follow @OsakaMetUniv_en and #OMUScience.

---

JOURNAL

PLoS ONE

DOI

10.1371/journal.pone.0275959 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Association between eating behavior and the immediate neural activity caused by viewing food images presented in and out of awareness: a magnetoencephalography study

Elucidating enzyme gene expression in filamentous fungi for efficient biomass energy production

Scientists discover new regulatory mechanisms in molds, potentially enabling a comprehensive high production method for various enzymes that degrade plant biomass

Peer-Reviewed Publication

OSAKA METROPOLITAN UNIVERSITY

 

IMAGE: A SCANNING ELECTRON MICROSCOPY IMAGE OF THE FILAMENTOUS FUNGUS A. ACULEATUS AND A GENE REGULATION MODEL IN A. ACULEATUS view more 

CREDIT: SHUJI TANI, OSAKA METROPOLITAN UNIVERSITY

Filamentous fungi have long been a good friend of sake brewers, but they might soon also be a sidekick for environmentalists. Osaka Metropolitan University researchers have revealed the regulatory mechanisms of enzyme production in a filamentous fungus that allows for efficient degradation of plant biomass, an alternative energy resource to petroleum.

Filamentous fungi (molds) are microorganisms with a long history of use in the fermentation of sake, soy sauce, cheese, and many other products. Such fermentation is a good example of the industrial use of filamentous fungi’s ability to secrete various enzymes in large quantities. Currently, plant biomass is attracting attention as an alternative to petroleum, which will eventually be depleted. Since hard plant cell walls are composed of various aromatics and polysaccharides, their degradation requires a large number of enzymes with diverse characteristics. Consequently, studies have been conducted to utilize filamentous fungi as a prominent source of enzymes for plant biomass degradation.

Delving into this field, a research team led by Associate Professor Shuji Tani, from the Graduate School of Agriculture at Osaka Metropolitan University, analyzed the regulatory mechanisms of carbohydrate-hydrolyzing enzyme production in the filamentous fungus Aspergillus aculeatus, which produces enzymes that have an excellent ability to degrade plant biomass.

Uridine diphosphate (UDP)-glucose 4-epimerase (Uge5) is well known as an enzyme involved in galactose metabolism. However, the team discovered that Uge5 also regulates the expression of degrading enzyme genes in A. aculeatus. This is the very first report of Uge5’s roles in selective gene expression in response to different types of inducing sugars in filamentous fungi.

These findings address the current technology challenge in establishing a much-wanted comprehensive high production method for various enzymes in filamentous fungi.

Professor Tani explained, “We constructed and screened a library containing approximately 9,000 gene-disrupted strains of Aspergillus aculeatus, and identified Uge5 as a novel regulatory factor that regulates the production of carbohydrate-hydrolyzing enzymes. The discovery of this new function took us by surprise. We plan to continue our research to elucidate phenomena that existing knowledge cannot explain.”

The research results were published in Applied Microbiology and Biotechnology on January 10, 2023.

###

About OMU

Osaka Metropolitan University is a new public university established by a merger between Osaka City University and Osaka Prefecture University in April 2022. For more science news, see https://www.omu.ac.jp/en/, and follow @OsakaMetUniv_en, or search #OMUScience. 

---

JOURNAL

Applied Microbiology and Biotechnology

DOI

10.1007/s00253-022-12337-8 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

A new function of a putative UDP-glucose 4-epimerase on the expression of glycoside hydrolase genes in Aspergillus aculeatus

Cubes outperform spheres as catalyst particles

Energy

Peer-Reviewed Publication

RUHR-UNIVERSITY BOCHUM

 

IMAGE: KRISTINA TSCHULIK (LEFT) AND HATEM AMIN ARE INVESTIGATING NANOPARTICLES AS CATALYSTS FOR GREEN HYDROGEN. view more 

CREDIT: © RUB, MARQUARD

How to make electrolysis competitive

The world must reduce CO2 emissions in order to combat climate change. To this end, so-called grey hydrogen is widely used today, which is obtained from oil and natural gas, while efforts are made to replace it with green hydrogen, which comes from renewable sources. Green hydrogen can be produced by electrolysis, a process where electricity is used to split water into hydrogen and oxygen. However, several challenges still need to be tackled to render electrolysis a competitive approach. At present, the water splitting process is only efficient to a limited degree, and there are not enough powerful, durable and cost-effective catalysts for it. “Currently, the most active electrocatalysts are based on the rare and expensive precious metals iridium, ruthenium and platinum,” lists Kristina Tschulik. “As researchers, our job is therefore to develop new, highly active electrocatalysts that are free of precious metals.”

Her research group studies catalysts in the form of base metal oxide nanoparticles that are a million times smaller than a human hair. Manufactured on an industrial scale, they vary in shape, size and chemical composition. “We use measurements to examine so-called catalyst inks, in which billions of particles are mixed with binders and additives,” outlines Kristina Tschulik. This method only allows researchers to measure an average performance, but not the activity of individual particles – which is what really matters. “If we knew which particle shape or crystal facet – the surfaces that point outwards – is most active, we could specifically produce particles with that exact shape,” says Dr. Hatem Amin, postdoctoral researcher in analytical chemistry at Ruhr University Bochum.

Winner of the nanoparticle race

The research group has developed a method to analyse individual particles directly in solution. This enables them to compare the activity of different nanomaterials with each other in order to understand the influence of particle properties such as their shape and composition on water splitting. “Our results indicate that cobalt oxide particles in the form of individual cubes are more active than spheres, as the latter always have several other, less active facets.”

Theory confirms experiment

The Bochum group’s experimental findings were confirmed by its cooperation partners headed by Professor Rossitza Pentcheva from the University of Duisburg-Essen as part of the Collaborative Research Centre/Transregio 247. The latter’s theoretical analyses indicate a change in the active catalyst regions, namely from cobalt atoms that are surrounded by oxygen atoms forming an octahedron to cobalt atoms that are surrounded by a tetrahedron. “Our insights into the correlation between particle shape and activity lay the foundation for knowledge-based design of viable catalyst materials and, consequently, for the transformation of our fossil energy and chemical industries towards a circular economy based on renewable energy sources and highly active, long-lasting catalysts,” concludes Kristina Tschulik.

---

JOURNAL

Advanced Functional Materials

DOI

10.1002/adfm.202370006 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Facet-Dependent Intrinsic Activity of Single Co3O4 Nanoparticles for Oxygen Evolution Reaction