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Plasma Jets Stabilize Water to Splash Less
< High-speed shadowgraph movie of water surface deformations induced by plasma impingement. >
A study by KAIST researchers revealed that an ionized gas jet blowing onto water, also known as a ‘plasma jet’, produces a more stable interaction with the water’s surface compared to a neutral gas jet. This finding reported in the April 1 issue of Nature will help improve the scientific understanding of plasma-liquid interactions and their practical applications in a wide range of industrial fields in which fluid control technology is used, including biomedical engineering, chemical production, and agriculture and food engineering.
Gas jets can create dimple-like depressions in liquid surfaces, and this phenomenon is familiar to anyone who has seen the cavity produced by blowing air through a straw directly above a cup of juice. As the speed of the gas jet increases, the cavity becomes unstable and starts bubbling and splashing.
“Understanding the physical properties of interactions between gases and liquids is crucial for many natural and industrial processes, such as the wind blowing over the surface of the ocean, or steelmaking methods that involve blowing oxygen over the top of molten iron,” explained Professor Wonho Choe, a physicist from KAIST and the corresponding author of the study.
However, despite its scientific and practical importance, little is known about how gas-blown liquid cavities become deformed and destabilized.
In this study, a group of KAIST physicists led by Professor Choe and the team’s collaborators from Chonbuk National University in Korea and the Jožef Stefan Institute in Slovenia investigated what happens when an ionized gas jet, also known as a ‘plasma jet’, is blown over water. A plasma jet is created by applying high voltage to a nozzle as gas flows through it, which causes the gas to be weakly ionized and acquire freely-moving charged particles.
The research team used an optical technique combined with high-speed imaging to observe the profiles of the water surface cavities created by both neutral helium gas jets and weakly ionized helium gas jets. They also developed a computational model to mathematically explain the mechanisms behind their experimental discovery.
The researchers demonstrated for the first time that an ionized gas jet has a stabilizing effect on the water’s surface. They found that certain forces exerted by the plasma jet make the water surface cavity more stable, meaning there is less bubbling and splashing compared to the cavity created by a neutral gas jet.
Specifically, the study showed that the plasma jet consists of pulsed waves of gas ionization propagating along the water’s surface so-called ‘plasma bullets’ that exert more force than a neutral gas jet, making the cavity deeper without becoming destabilized.
“This is the first time that this phenomenon has been reported, and our group considers this as a critical step forward in our understanding of how plasma jets interact with liquid surfaces. We next plan to expand this finding through more case studies that involve diverse plasma and liquid characteristics,” said Professor Choe.
This work was supported by KAIST as part of the High-Risk and High-Return Project, the National Research Foundation of Korea (NRF), and the Slovenian Research Agency (ARRS).
Image Credit: Professor Wonho Choe, KAIST
Usage Restrictions: News organizations may use or redistribute these materials, with proper attribution, as part of news coverage of this paper only.
Publication: Park, S., et al. (2021) Stabilization of liquid instabilities with ionized gas jets. Nature, Vol. No. 592, Issue No. 7852, pp. 49-53. Available online at https://doi.org/10.1038/s41586-021-03359-9
Profile:
Wonho Choe, Ph.D.
Professor
wchoe@kaist.ac.kr
https://gdpl.kaist.ac.kr/
Gas Discharge Physics Laboratory (GDPL)
Department of Nuclear and Quantum Engineering
Department of Physics
Impurity and Edge Plasma Research Center (IERC)
http://kaist.ac.kr/en/
Korea Advanced Institute of Science and Technology (KAIST)
Daejeon, Republic of Korea
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2021.04.01 View 12584 -
Professor Jihee Kim Wins the Lucas Prize for Her Income Inequality Theory
Professor Jihee Kim from the School of Business and Technology Management at KAIST was announced as one of two winners of the 2021 Robert E. Lucas Jr. Prize. Professor Kim was recognized for having provided an empirical analysis on engines of income growth, sources of income inequality, and their rich interplay in her paper published in the Journal of Political Economy (JPE) in October 2018. The co-author of this study, Professor Charles I. Jones at Stanford University, was honored to be another awardee of this year’s Lucas Prize.
The Robert E. Lucas Jr. Prize, simply known as the Lucas Prize, is awarded biannually for the most interesting paper in the area of Dynamic Economics published in the leading economics journal JPE in the preceding two years. The prize was established in 2016 in celebration of the 1995 Nobel Prize in Economics Laureate Dr. Lucas’s seminal contributions to economics. The two former prizes were presented in 2019 and 2017 respectively.
Professor Kim and Professor Jones, in their award-winning paper titled 'A Schumpeterian Model of Top Income Inequality', observed that top income inequality was relatively low and stable between 1960 and 1980, but then rose sharply in some countries, including the United States and the United Kingdom.
The authors focused on entrepreneurial activities and the resulting income as the driving force of income inequality. They assumed that the forces that increased the efforts of fast-growing entrepreneurs to improve their products or increased productivity of their efforts could increase income inequality. On the other hand, the forces that enhanced creative destruction or that raised the rate at which high-growth entrepreneurs lost that status could decrease income inequality, according to the authors’ theory.
Professor Kim explained, “Various economic forces due to globalization, the advancement in AI and IT technologies, taxes, and policies related to innovation blocking may explain the varied patterns in income inequality.”
“Through follow-up research, I will continue developing economic theory models that can analyze the impact of changes such as income tax rates and salary negotiations on income inequality,” she added.
Professor Kim received her bachelor’s degree from the KAIST School of Computing in 2005 and pursued her graduates studies at Stanford University, acquiring a master’s degree in economics in 2011 and a doctoral degree in management science and engineering in 2013.
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2021.03.26 View 9720 -
Upbeat Message for a New Future at President Lee’s Inauguration
KAIST’s 17th President Kwang Hyung Lee reaffirmed his commitment to building a new future preparing for the post-AI era during his inauguration on March 8. The Board of Trustees selected the former provost and executive vice president as the new president, succeeding 16th President Sung-Chul Shin whose four-year term expired last month.
In his inaugural address, President Lee proposed a new culture strategy, ‘QAIST’ designed to foster more creative talents and ensure innovative research infrastructure. He said that the best way to stand out as a leading global university is to carve out our own distinctness.
The ceremony was live streamed via YouTube due to the social distancing guidelines, with a very limited number of distinguished guests attending. Among them were President Lee’s former student Jung-Ju Kim who started Nexon, now the world’s most popular online game company, and former Chairman of the Board of Trustees Moon-Soul Chung who President Lee worked with when he made the endowment for establishing the Department of Bio and Brain Engineering in 2001 and the Moon Soul Graduate School of Future Strategy in 2013.
In his induction speech, Chairman Woo Sik Kim of the Board of Trustees said that President Lee is a proven leader who has deep insight and passion and he will help KAIST make a new leap forward. “I believe that Professor Lee will be the right leader at this critical moment for the university, ushering in a new future for KAIST as it turns 50 this year.”
President Lee explained that for the next 50 years, KAIST should double down to identify the challenges humanity faces, then define and resolve them with unyielding innovations in education, research, technology commercialization, and internationalization.
“We definitely should pull together to produce sustainable global value that will serve the prosperity and happiness of all humanity, not only our nation. We will become one of the top 10 universities in the world when we realize all these goals. We can live up to the people’s expectations by producing creative global talent, staying ahead of new research topics, and producing corporations that will lead the nation’s industries.”
“To this end, I will continue to strive to help us achieve our mission of becoming a ‘Global Value Creative Leading University’ as described in KAIST Vision 2031. I will do my utmost to bring about the ‘KAIST New Culture Strategy, QAIST’ for a post-AI era.”
He added that he would like to inspire students and faculty to have more humanistic approaches in their education and learning. The ‘Q’ in “QAIST” refers to questioning. President Lee believes that the learning starts with questions and being curious about something. “We will innovate the educational system to have them question everything.”
Then, he said that he will focus on ‘A’dvanced research to prepare for the post AI-era. “We should be the first mover who can define and solve new problems. It’s more important to be the ‘first’ one than the ‘best’ one.” He also said he will create a new culture that failing would not be stigmatized, offering more chances after failing.
‘I’nternationalization is another vision the new president will continue to pursue. He plans to embrace greater diversity on the campus to achieve goals of 15% international faculty, 25% female faculty, and 15% international students by reshaping the recruiting policy. He will continue to expand KAIST campuses overseas.
‘S’tartup and technology commercialization will be the crucial areas where the president will make innovations. “I will fully support any startups at KAIST. I encourage every lab to start a startup,” he stressed. President Lee said he plans to increase KAIST’s annual revenue from technology commercialization fees to 100 billion KRW in 10 years, a step to secure financial independence. He plans to privatize the Institute of Technology Value Creation, which is responsible for technology commercialization at KAIST to enhance its competitiveness.
‘T’rust building is the prerequisite value for creating transparent and reliable management in finance and HR. President Lee said he would like to make a new organizational culture that will be more ethical, responsible, and autonomous with a high standard of integrity.
His predecessor, President Sung-Chul Shin lauded his successor in his congratulatory speech saying, “He is a president prepared for this job.”
“I have known him for more than 30 years. He is a man of action. With unparalleled ideas and prompt execution, he carried out all his duties efficiently for the Committee of Vision 2031 that he chaired, and played a central role in establishing the full vision of KAIST. First and foremost, he is a man of great passion, with a firm vision but a warm heart.”
Nexon founder and Chairman Jung-Ju Kim also made an emotional tribute to his former professor. Holding back tears, he said, “I was not a good student. I was struggling in my graduate courses so I had to drop out of my PhD course. But Professor Lee and his wife never gave up on me. They were so kind to me and were always encouraging despite my disappointing days. I am now ready to do something good for KAIST, for Professor Lee, and for the future of our society. I believe that President Lee will guide us down the new path for KAIST.” IDIS Holdings CEO Young-Dal Kim also attended the ceremony to congratulate his former professor on his inauguration.
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2021.03.09 View 10650 -
Deep-Learning and 3D Holographic Microscopy Beats Scientists at Analyzing Cancer Immunotherapy
Live tracking and analyzing of the dynamics of chimeric antigen receptor (CAR) T-cells targeting cancer cells can open new avenues for the development of cancer immunotherapy. However, imaging via conventional microscopy approaches can result in cellular damage, and assessments of cell-to-cell interactions are extremely difficult and labor-intensive. When researchers applied deep learning and 3D holographic microscopy to the task, however, they not only avoided these difficultues but found that AI was better at it than humans were.
Artificial intelligence (AI) is helping researchers decipher images from a new holographic microscopy technique needed to investigate a key process in cancer immunotherapy “live” as it takes place. The AI transformed work that, if performed manually by scientists, would otherwise be incredibly labor-intensive and time-consuming into one that is not only effortless but done better than they could have done it themselves. The research, conducted by the team of Professor YongKeun Park from the Department of Physics, appeared in the journal eLife last December.
A critical stage in the development of the human immune system’s ability to respond not just generally to any invader (such as pathogens or cancer cells) but specifically to that particular type of invader and remember it should it attempt to invade again is the formation of a junction between an immune cell called a T-cell and a cell that presents the antigen, or part of the invader that is causing the problem, to it. This process is like when a picture of a suspect is sent to a police car so that the officers can recognize the criminal they are trying to track down. The junction between the two cells, called the immunological synapse, or IS, is the key process in teaching the immune system how to recognize a specific type of invader.
Since the formation of the IS junction is such a critical step for the initiation of an antigen-specific immune response, various techniques allowing researchers to observe the process as it happens have been used to study its dynamics. Most of these live imaging techniques rely on fluorescence microscopy, where genetic tweaking causes part of a protein from a cell to fluoresce, in turn allowing the subject to be tracked via fluorescence rather than via the reflected light used in many conventional microscopy techniques.
However, fluorescence-based imaging can suffer from effects such as photo-bleaching and photo-toxicity, preventing the assessment of dynamic changes in the IS junction process over the long term. Fluorescence-based imaging still involves illumination, whereupon the fluorophores (chemical compounds that cause the fluorescence) emit light of a different color. Photo-bleaching or photo-toxicity occur when the subject is exposed to too much illumination, resulting in chemical alteration or cellular damage.
One recent option that does away with fluorescent labelling and thereby avoids such problems is 3D holographic microscopy or holotomography (HT). In this technique, the refractive index (the way that light changes direction when encountering a substance with a different density—why a straw looks like it bends in a glass of water) is recorded in 3D as a hologram.
Until now, HT has been used to study single cells, but never cell-cell interactions involved in immune responses. One of the main reasons is the difficulty of “segmentation,” or distinguishing the different parts of a cell and thus distinguishing between the interacting cells; in other words, deciphering which part belongs to which cell.
Manual segmentation, or marking out the different parts manually, is one option, but it is difficult and time-consuming, especially in three dimensions. To overcome this problem, automatic segmentation has been developed in which simple computer algorithms perform the identification.
“But these basic algorithms often make mistakes,” explained Professor YongKeun Park, “particularly with respect to adjoining segmentation, which of course is exactly what is occurring here in the immune response we’re most interested in.”
So, the researchers applied a deep learning framework to the HT segmentation problem. Deep learning is a type of machine learning in which artificial neural networks based on the human brain recognize patterns in a way that is similar to how humans do this. Regular machine learning requires data as an input that has already been labelled. The AI “learns” by understanding the labeled data and then recognizes the concept that has been labelled when it is fed novel data. For example, AI trained on a thousand images of cats labelled “cat” should be able to recognize a cat the next time it encounters an image with a cat in it. Deep learning involves multiple layers of artificial neural networks attacking much larger, but unlabeled datasets, in which the AI develops its own ‘labels’ for concepts it encounters.
In essence, the deep learning framework that KAIST researchers developed, called DeepIS, came up with its own concepts by which it distinguishes the different parts of the IS junction process. To validate this method, the research team applied it to the dynamics of a particular IS junction formed between chimeric antigen receptor (CAR) T-cells and target cancer cells. They then compared the results to what they would normally have done: the laborious process of performing the segmentation manually. They found not only that DeepIS was able to define areas within the IS with high accuracy, but that the technique was even able to capture information about the total distribution of proteins within the IS that may not have been easily measured using conventional techniques.
“In addition to allowing us to avoid the drudgery of manual segmentation and the problems of photo-bleaching and photo-toxicity, we found that the AI actually did a better job,” Professor Park added.
The next step will be to combine the technique with methods of measuring how much physical force is applied by different parts of the IS junction, such as holographic optical tweezers or traction force microscopy.
-Profile
Professor YongKeun Park
Department of Physics
Biomedical Optics Laboratory
http://bmol.kaist.ac.kr
KAIST
2021.02.24 View 14970 -
Top University Leaders Urge Innovation for the Post-COVID Era at the KAIST Summit
- Presidents of KAIST, MIT, Tokyo Tech, and Northwestern to define new roles and responsibilities of universities for the post-COVID and 4IR eras during an online summit in celebration of KAIST’s 50th anniversary. -
Universities are facing ever-mounting pressure to address impacts brought on by COVID-19 and the emerging technologies of the Fourth Industrial Revolution (4IR).
Presidents from MIT, Tokyo Tech, and Northwestern University will join the KAIST Summit to explore new directions for higher education during the post-COVID era intertwined with the 4IR. They agree that addressing these dual challenges requires pushing for innovations to rebuild the competitive edges of universities.
This summit is one of KAIST’s series of events to envision the future of KAIST and higher education in celebration of its 50th anniversary. The online summit will be live streamed on KAIST’s official YouTube channel (https://www.youtube.com/c/KAISTofficial) on February 3, 2021, from 10 a.m. to 12:00 p.m. Korean time (February 2, 7:00-9:00 p.m. CST and 8:00-10:00 p.m. EST, respectively).
The KAIST Summit titled “The Roles and Responsibilities of Universities in a Global Crisis” will discuss a range of issues affecting many aspects of universities in the coming decades.
“This summit will allow us to measure the level of risk that universities face today and will face in the future. Although there will be varying views on what a post-COVID world might look like, one thing for sure is that universities cannot go back to the way they used to exist and operate. Moreover, the 4IR continues to infiltrate and shake up our daily lives. Changes are inevitable, and universities must pursue bold and innovative responses to remain sustainable and relevant to society,” said KAIST President Sung-Chul Shin on the background of hosting the event.
The keynote speakers include KAIST President Shin, MIT President L. Rafael Reif, Tokyo Tech President Kazuya Masu, and Northwestern University President Morton Schapiro. After the keynote speech session, the speakers will take part in a panel discussion on three topics: “The Digital Divide,” “Emerging Challenges in AI,” and “Social Entrepreneurship and University-Industry Collaboration.” A Q&A session with an online audience consisting of KAIST faculty, staff, and students as well as high school students across the nation will follow shortly afterwards.
President Reif of MIT will congratulate KAIST on its successful 50-year journey from meager beginnings to achieving its current status as one of the finest global universities in science and technology. Then he will give a talk titled “Universities as Engines of Change” to present how universities have played a critical role in advancing solutions to humanity’s most urgent problems.
President Masu of Tokyo Tech will stress the importance of universities’ continuous dialogue with society as drivers of innovation. In his speech titled “Designing Our Future—Tokyo Tech DLab’s Approach,” he will introduce the activities of Tokyo Tech’s Laboratory for Design of Social Innovation in Global Networks (DLab) and explain how DLab collaborates for the future with members of society.
President Schapiro of Northwestern University will speak about how universities might incorporate the lessons they learned in dealing with COVID-19 to improve their research, teaching, and public service in the post-pandemic era. He will also look into issues arising from changing labor market needs associated with the 4IR and the aftermath of COVID-19 in his talk titled “The University in the ‘New Normal.’”
Finally, President Shin of KAIST will deliver a presentation on the “Visions & Innovations for the Next Dream of KAIST.” He will reflect on the remarkable track record from KAIST’s first 50 years and how it has contributed significantly to the rapid growth of Korea as a hi-tech powerhouse. Furthermore, he will elaborate on a new vision for the development of KAIST over the next 50 years and roll out a set of strategic innovation plans in the five areas of education, research, technology commercialization, globalization, and future strategy.
In the panel discussion, the four presidents will dive into a more intense conversation on such topics as universities’ role in bridging the increasing digital divide through their research, education, and international cooperation; the socioeconomic implications and ethical challenges of the fast deployment of AI and robotics; 4IR disruptions that will transform higher education; ways to foster social innovation and youth entrepreneurship; and how to build university-industry cooperation.
More information on KAIST’s 50th anniversary celebrations can be found on its special celebratory website at https://50.kaist.ac.kr/eng/. The official anniversary ceremony is scheduled for February 16, 2021, from 10 a.m. Korean time, and live-streaming will also be made available on KAIST’s official YouTube channel at https://www.youtube.com/c/KAISTofficial.
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2021.02.01 View 18610 -
Wirelessly Rechargeable Soft Brain Implant Controls Brain Cells
Researchers have invented a smartphone-controlled soft brain implant that can be recharged wirelessly from outside the body. It enables long-term neural circuit manipulation without the need for periodic disruptive surgeries to replace the battery of the implant. Scientists believe this technology can help uncover and treat psychiatric disorders and neurodegenerative diseases such as addiction, depression, and Parkinson’s.
A group of KAIST researchers and collaborators have engineered a tiny brain implant that can be wirelessly recharged from outside the body to control brain circuits for long periods of time without battery replacement. The device is constructed of ultra-soft and bio-compliant polymers to help provide long-term compatibility with tissue. Geared with micrometer-sized LEDs (equivalent to the size of a grain of salt) mounted on ultrathin probes (the thickness of a human hair), it can wirelessly manipulate target neurons in the deep brain using light.
This study, led by Professor Jae-Woong Jeong, is a step forward from the wireless head-mounted implant neural device he developed in 2019. That previous version could indefinitely deliver multiple drugs and light stimulation treatment wirelessly by using a smartphone. For more, Manipulating Brain Cells by Smartphone.
For the new upgraded version, the research team came up with a fully implantable, soft optoelectronic system that can be remotely and selectively controlled by a smartphone. This research was published on January 22, 2021 in Nature Communications.
The new wireless charging technology addresses the limitations of current brain implants. Wireless implantable device technologies have recently become popular as alternatives to conventional tethered implants, because they help minimize stress and inflammation in freely-moving animals during brain studies, which in turn enhance the lifetime of the devices. However, such devices require either intermittent surgeries to replace discharged batteries, or special and bulky wireless power setups, which limit experimental options as well as the scalability of animal experiments.
“This powerful device eliminates the need for additional painful surgeries to replace an exhausted battery in the implant, allowing seamless chronic neuromodulation,” said Professor Jeong. “We believe that the same basic technology can be applied to various types of implants, including deep brain stimulators, and cardiac and gastric pacemakers, to reduce the burden on patients for long-term use within the body.”
To enable wireless battery charging and controls, researchers developed a tiny circuit that integrates a wireless energy harvester with a coil antenna and a Bluetooth low-energy chip. An alternating magnetic field can harmlessly penetrate through tissue, and generate electricity inside the device to charge the battery. Then the battery-powered Bluetooth implant delivers programmable patterns of light to brain cells using an “easy-to-use” smartphone app for real-time brain control.
“This device can be operated anywhere and anytime to manipulate neural circuits, which makes it a highly versatile tool for investigating brain functions,” said lead author Choong Yeon Kim, a researcher at KAIST.
Neuroscientists successfully tested these implants in rats and demonstrated their ability to suppress cocaine-induced behaviour after the rats were injected with cocaine. This was achieved by precise light stimulation of relevant target neurons in their brains using the smartphone-controlled LEDs. Furthermore, the battery in the implants could be repeatedly recharged while the rats were behaving freely, thus minimizing any physical interruption to the experiments.
“Wireless battery re-charging makes experimental procedures much less complicated,” said the co-lead author Min Jeong Ku, a researcher at Yonsei University’s College of Medicine.
“The fact that we can control a specific behaviour of animals, by delivering light stimulation into the brain just with a simple manipulation of smartphone app, watching freely moving animals nearby, is very interesting and stimulates a lot of imagination,” said Jeong-Hoon Kim, a professor of physiology at Yonsei University’s College of Medicine. “This technology will facilitate various avenues of brain research.”
The researchers believe this brain implant technology may lead to new opportunities for brain research and therapeutic intervention to treat diseases in the brain and other organs.
This work was supported by grants from the National Research Foundation of Korea and the KAIST Global Singularity Research Program.
-Profile
Professor Jae-Woong Jeong
https://www.jeongresearch.org/
School of Electrical Engineering
KAIST
2021.01.26 View 28804 -
Expanding the Biosynthetic Pathway via Retrobiosynthesis
- Researchers reports a new strategy for the microbial production of multiple short-chain primary amines via retrobiosynthesis. -
KAIST metabolic engineers presented the bio-based production of multiple short-chain primary amines that have a wide range of applications in chemical industries for the first time. The research team led by Distinguished Professor Sang Yup Lee from the Department of Chemical and Biomolecular Engineering designed the novel biosynthetic pathways for short-chain primary amines by combining retrobiosynthesis and a precursor selection step.
The research team verified the newly designed pathways by confirming the in vivo production of 10 short-chain primary amines by supplying the precursors. Furthermore, the platform Escherichia coli strains were metabolically engineered to produce three proof-of-concept short-chain primary amines from glucose, demonstrating the possibility of the bio-based production of diverse short-chain primary amines from renewable resources. The research team said this study expands the strategy of systematically designing biosynthetic pathways for the production of a group of related chemicals as demonstrated by multiple short-chain primary amines as examples.
Currently, most of the industrial chemicals used in our daily lives are produced with petroleum-based products. However, there are several serious issues with the petroleum industry such as the depletion of fossil fuel reserves and environmental problems including global warming. To solve these problems, the sustainable production of industrial chemicals and materials is being explored with microorganisms as cell factories and renewable non-food biomass as raw materials for alternative to petroleum-based products. The engineering of these microorganisms has increasingly become more efficient and effective with the help of systems metabolic engineering – a practice of engineering the metabolism of a living organism toward the production of a desired metabolite. In this regard, the number of chemicals produced using biomass as a raw material has substantially increased.
Although the scope of chemicals that are producible using microorganisms continues to expand through advances in systems metabolic engineering, the biological production of short-chain primary amines has not yet been reported despite their industrial importance. Short-chain primary amines are the chemicals that have an alkyl or aryl group in the place of a hydrogen atom in ammonia with carbon chain lengths ranging from C1 to C7. Short-chain primary amines have a wide range of applications in chemical industries, for example, as a precursor for pharmaceuticals (e.g., antidiabetic and antihypertensive drugs), agrochemicals (e.g., herbicides, fungicides and insecticides), solvents, and vulcanization accelerators for rubber and plasticizers. The market size of short-chain primary amines was estimated to be more than 4 billion US dollars in 2014.
The main reason why the bio-based production of short-chain primary amines was not yet possible was due to their unknown biosynthetic pathways. Therefore, the team designed synthetic biosynthetic pathways for short-chain primary amines by combining retrobiosynthesis and a precursor selection step. The retrobiosynthesis allowed the systematic design of a biosynthetic pathway for short-chain primary amines by using a set of biochemical reaction rules that describe chemical transformation patterns between a substrate and product molecules at an atomic level.
These multiple precursors predicted for the possible biosynthesis of each short-chain primary amine were sequentially narrowed down by using the precursor selection step for efficient metabolic engineering experiments.
“Our research demonstrates the possibility of the renewable production of short-chain primary amines for the first time. We are planning to increase production efficiencies of short-chain primary amines. We believe that our study will play an important role in the development of sustainable and eco-friendly bio-based industries and the reorganization of the chemical industry, which is mandatory for solving the environmental problems threating the survival of mankind,” said Professor Lee.
This paper titled “Microbial production of multiple short-chain primary amines via retrobiosynthesis” was published in Nature Communications. This work was supported by the Technology Development Program to Solve Climate Changes on Systems Metabolic Engineering for Biorefineries from the Ministry of Science and ICT through the National Research Foundation (NRF) of Korea.
-Publication
Dong In Kim, Tong Un Chae, Hyun Uk Kim, Woo Dae Jang, and Sang Yup Lee. Microbial production of multiple short-chain primary amines via retrobiosynthesis. Nature Communications ( https://www.nature.com/articles/s41467-020-20423-6)
-Profile
Distinguished Professor Sang Yup Lee
leesy@kaist.ac.kr
Metabolic &Biomolecular Engineering National Research Laboratory
http://mbel.kaist.ac.kr
Department of Chemical and Biomolecular Engineering
KAIST
2021.01.14 View 14604 -
KAIST Mobile Clinic Module to Fill Negative Pressure Ward Shortage
Efficient versatile ready-for-rapid building system of MCM will serve as both a triage unit and bridge center in emergency medical situations
A team from KAIST has developed a low-cost and ready-for-rapid-production negative pressure room called a Mobile Clinic Module (MCM). The MCM is expandable, moveable, and easy to store through a combination of negative pressure frames, air tents, and multi-function panels.
The MCM expects to quickly meet the high demand for negative pressure beds in the nation and eventually many other countries where the third wave of COVID-19 is raging. The module is now ready to be rolled out after a three-week test period at the Korea Cancer Center Hospital.
Professor Tek-Jin Nam’s team swung into action, rapidly working together with researchers, engineers with expertise in mechanical design, and a team of clinical doctors to complete the MCM as one of KAIST’s New Deal R&D initiatives launched last July.
Professor Nam cites ‘expandability’ as the key feature of the MCM. Eventually, it will serve as both a triage unit and bridge center in emergency medical situations.
“The module is a very efficient and versatile unit building system. It takes approximately two hours to build the basic MCM unit, which comprises four negative pressure bed rooms, nurse’s station, locker room, and treatment room. We believe this will significantly contribute to relieving the drastic need for negative pressure beds and provide a place for monitoring patients with moderate symptoms,” said Professor Nam.
“It will also be helpful for managing less-severe patients who need to be monitored daily in quarantined rooms or as bridge stations where on-site medical staff can provide treatment and daily monitoring before hospitalization. These wards can be efficiently deployed either inside or outside existing hospitals.”
The research team specially designed the negative pressure frame to ensure safety level A for the negative pressure room, which is made of a multi-function panel wall and roofed with an air tent. The multi-function panels can hold medical appliances such as ventilators, oxygen and bio-signal monitors.
Positive air pressure devices supply fresh air from outside the tent. An air pump and controller maintain air beam pressure, while filtering exhausted air. An internal air information monitoring system efficiently controls room air pressure and purifies the air.
While a conventional negative pressure bed is reported to cost approximately 3.5 billion KRW (50 billion won for a ward), this module is estimated to cost 0.75 billion won each (10 billion won for a ward), cutting the costs by approximately 80%.
The MCM is designed to be easily transported and relocated due to its volume, weight, and maintainability. This module requires only one-fourth of the volume of existing wards and takes up approximately 40% of their weight. The unit can be transported in a 40-foot container truck.
“We believe this will significantly contribute to relieving the drastic need for negative pressure beds and provide a place for monitoring patients with moderate symptoms. We look forward to the MCM upgrading epidemic management resources around the world.”
Professor Nam’s team is also developing antiviral solutions and devices such as protective gear, sterilizers, and test kits under the KAIST New Deal R&D Initiative that was launched to promptly and proactively respond to the epidemic. More than 45 faculty members and researchers at KAIST are collaborating with industry and clinical hospitals to develop the antiviral technology that will improve preventive measures, diagnoses, and treatment.
2021.01.07 View 13953 -
Astrocytes Eat Connections to Maintain Plasticity in Adult Brains
Developing brains constantly sprout new neuronal connections called synapses as they learn and remember. Important connections — the ones that are repeatedly introduced, such as how to avoid danger — are nurtured and reinforced, while connections deemed unnecessary are pruned away. Adult brains undergo similar pruning, but it was unclear how or why synapses in the adult brain get eliminated.
Now, a team of KAIST researchers has found the mechanism underlying plasticity and, potentially, neurological disorders in adult brains. They published their findings on December 23 in Nature.
“Our findings have profound implications for our understanding of how neural circuits change during learning and memory, as well as in diseases,” said paper author Won-Suk Chung, an assistant professor in the Department of Biological Sciences at KAIST. “Changes in synapse number have strong association with the prevalence of various neurological disorders, such as autism spectrum disorder, schizophrenia, frontotemporal dementia, and several forms of seizures.”
Gray matter in the brain contains microglia and astrocytes, two complementary cells that, among other things, support neurons and synapses. Microglial are a frontline immunity defense, responsible for eating pathogens and dead cells, and astrocytes are star-shaped cells that help structure the brain and maintain homeostasis by helping to control signaling between neurons. According to Professor Chung, it is generally thought that microglial eat synapses as part of its clean-up effort in a process known as phagocytosis.
“Using novel tools, we show that, for the first time, it is astrocytes and not microglia that constantly eliminate excessive and unnecessary adult excitatory synaptic connections in response to neuronal activity,” Professor Chung said. “Our paper challenges the general consensus in this field that microglia are the primary synapse phagocytes that control synapse numbers in the brain.”
Professor Chung and his team developed a molecular sensor to detect synapse elimination by glial cells and quantified how often and by which type of cell synapses were eliminated. They also deployed it in a mouse model without MEGF10, the gene that allows astrocytes to eliminate synapses. Adult animals with this defective astrocytic phagocytosis had unusually increased excitatory synapse numbers in the hippocampus. Through a collaboration with Dr. Hyungju Park at KBRI, they showed that these increased excitatory synapses are functionally impaired, which cause defective learning and memory formation in MEGF10 deleted animals.
“Through this process, we show that, at least in the adult hippocampal CA1 region, astrocytes are the major player in eliminating synapses, and this astrocytic function is essential for controlling synapse number and plasticity,” Chung said.
Professor Chung noted that researchers are only beginning to understand how synapse elimination affects maturation and homeostasis in the brain. In his group’s preliminary data in other brain regions, it appears that each region has different rates of synaptic elimination by astrocytes. They suspect a variety of internal and external factors are influencing how astrocytes modulate each regional circuit, and plan to elucidate these variables.
“Our long-term goal is understanding how astrocyte-mediated synapse turnover affects the initiation and progression of various neurological disorders,” Professor Chung said. “It is intriguing to postulate that modulating astrocytic phagocytosis to restore synaptic connectivity may be a novel strategy in treating various brain disorders.”
This work was supported by the Samsung Science & Technology Foundation, the National Research Foundation of Korea, and the Korea Brain Research Institute basic research program.
Other contributors include Joon-Hyuk Lee and Se Young Lee, Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST); Ji-young Kim, Hyoeun Lee and Hyungju Park; Research Group for Neurovascular Unit, Korea Brain Research Institute (KBRI); Seulgi Noh, and Ji Young Mun, Research Group for Neural Circuit, KBRI. Kim, Noh and Park are also affiliated with the Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST).
-Profile
Professor Won-Suk Chung
Department of Biological Sciences
Gliabiology Lab (https://www.kaistglia.org/)
KAIST
-Publication
"Astrocytes phagocytose adult hippocampal synapses for circuit homeostasis"
https://doi.org/10.1038/s41586-020-03060-3
2020.12.24 View 13623 -
Electrosprayed Micro Droplets Help Kill Bacteria and Viruses
With COVID-19 raging around the globe, researchers are doubling down on methods for developing diverse antimicrobial technologies that could be effective in killing a virus, but harmless to humans and the environment.
A recent study by a KAIST research team will be one of the responses to such efforts. Professor Seung Seob Lee and Dr. Ji-hun Jeong from the Department of Mechanical Engineering developed a harmless air sterilization prototype featuring electrosprayed water from a polymer micro-nozzle array. This study is one of the projects being supported by the KAIST New Deal R&D Initiative in response to COVID-19. Their study was reported in Polymer.
The electrosprayed microdroplets encapsulate reactive oxygen species such as hydroxyl radicals, superoxides that are known to have an antimicrobial function. The encapsulation prolongs the life of reactive oxygen species, which enable the droplets to perform their antimicrobial function effectively. Prior research has already proven the antimicrobial and encapsulation effects of electrosprayed droplets.
Despite its potential for antimicrobial applications, electrosprayed water generally operates under an electrical discharge condition, which can generate ozone. The inhalation of ozone is known to cause damage to the respiratory system of humans. Another technical barrier for electrospraying is the low flow rate problem. Since electrospraying exhibits the dependence of droplet size on the flow rate, there is a limit for the amount of water microdroplets a single nozzle can produce.
With this in mind, the research team developed a dielectric polymer micro-nozzle array to perform the multiplexed electrospraying of water without electrical discharge. The polymer micro-nozzle array was fabricated using the MEMS (Micro Electro-Mechanical System) process. According to the research team, the nozzle can carry five to 19 micro-nozzles depending on the required application.
The high aspect ratio of the micro-nozzle and an in-plane extractor were proposed to concentrate the electric field at the tip of the micro-nozzle, which prevents the electrical discharge caused by the high surface tension of water. A micro-pillar array with a hydrophobic coating around the micro-nozzle was also proposed to prevent the wetting of the micro-nozzle array.
The polymer micro-nozzle array performed in steady cone jet mode without electrical discharge as confirmed by high-speed imaging and nanosecond pulsed imaging. The water microdroplets were measured to be in the range of six to 10 μm and displayed an antimicrobial effect on Escherichia coli and Staphylococcus aureus.
Professor Lee said, “We believe that this research can be applied to air conditioning products in areas that require antimicrobial and humidifying functions.”
Publication:
Jeong, J. H., et al. (2020) Polymer micro-atomizer for water electrospray in the cone jet mode. Polymer. Vol. No. 194, 122405. Available online at https://doi.org/10.1016/j.polymer.2020.122405
Profile: Seung Seob Lee, Ph.D.
sslee97@kaist.ac.kr
http://mmst.kaist.ac.kr/
Professor
Department of Mechanical Engineering (ME)
Korea Advanced Institute of Science and Technology (KAIST)
https://www.kaist.ac.kr
Daejeon 34141, Korea
Profile: Ji-hun Jeong, Ph.D.
jiuni6022@kaist.ac.kr
Postdoctoral researcher
Department of Mechanical Engineering (ME)
Korea Advanced Institute of Science and Technology (KAIST)
https://www.kaist.ac.kr
Daejeon 34141, Korea
(END)
2020.12.21 View 16980 -
Emeritus Professor Jae-Kyu Lee Wins the AIS LEO Award
Emeritus Professor Jae-Kyu Lee has won the Association for Information Systems LEO Award 2020. Professor Lee, the first Korean to receive the LEO Award, was recognized for his research and development in preventative cyber security, which is a major part of the efforts he leads to realize what Professor Lee has named "Bright Internet."
Established in 1999, this award was named after the world’s first business application of computing, the Lyons Electronic Office and recognizes outstanding individuals in the field of information systems. The LEO Award recognized four winners including Professor Lee this year.
He has been professor and HHI Chair Professor at KAIST from 1985 to 2016 since he has received his Ph.D. in information and operations management from the Wharton School, University of Pennsylvania. He served as the Dean of College of Business and supervised around 30 doctoral students. He is currently the Distinguished Professor of School of Management at Xi’an Jiaotong University.
His research mainly focused on the creation of Bright Internet for preventive cybersecurity, improving relevance of research from Axiomatic Theories, and development of AI for electronic commerce and managerial decision support.
He is a fellow and was the president of the Association for Information Systems, and co-chaired the International Conference on Information Systems in 2017. He was the founder of Principles for the Bright Internet and established the Bright Internet Research Center at KAIST and Xi’an Jiatong University. He also established the Bright Internet Global Summit since ICIS 2017 in Seoul, and organized the Bright Internet Project Consortium in 2019 as a combined effort of academia-industry partnership. (www.brightinternet.org.)
He was a charter member of the Pacific Asia Conference in Information Systems, and served as conference chair. He was the founder editor-in-chief of the journal, Electronic Commerce Research and Applications (Elsevier), and was the founding chair of the International Conference on Electronic Commerce. In Korea, her served as president of Korea Society of Management Information Systems and Korea Society of Intelligent Information Systems.
"I am honored to be designated the first Korean winner of the honorable LEO Award," Lee said. "Based on my life-long efforts for developments in the field, I will continue to contribute to the research and development of information media systems."
2020.12.16 View 8688 -
Feel the Force with ElaStick
ElaStick, a handheld variable stiffness display, renders the dynamic haptic response of a flexible object
Haptic controllers play an important role in providing rich and immersive virtual reality experiences. Professor Andrea Bianchi’s team in the Department of Industrial Design recreated the haptic response of flexible objects made of different materials and with different shapes by changing the stiffness of a custom-controller – ElaStick.
ElaStick is a portable hand-held force-feedback controller that is capable of rendering the illusion of how flexible and deformable objects feel when held in the hand. This VR haptic controller can change its stiffness in two directions independently and continuously. Since providing haptic feedback enhances the VR experience, researchers have suggested numerous approaches for rendering the physical properties of virtual objects - such as weights, the movement of mass, impacts, and damped oscillations.
The research team designed a new mechanism based on a quaternion joint and four variable-stiffness tendons. The quaternion joint is a two-DoF bending joint that enables ElaStick to bend and oscillate in any direction using a pair of tendons with varying stiffness. In fact, each tendon around the joint is made of a series of elastic rubber bands and inelastic fishing lines and can vary its stiffness by changing the proportion of the two materials. Thanks to these structures, each pair of tendons can behave independently, controlling the anisotropic characteristics of the entire device.
“The main challenge was to implement the mechanism to control the stiffness while maintaining independence between deformations in two perpendicular directions,” said Professor Bianchi.
The research team successfully measured the relative threshold of human perception on the stiffness of a handheld object. The results showed that the just-noticeable difference (JND) of human perception of stiffness is at most about 30% of the change from the initial value. It also found that appropriate haptic responses significantly enhance the quality of the VR experience. The research team surveyed the perceived realism, immersion, and enjoyment of participants after they played with various flexible objects in VR.
“It is meaningful that the haptic feedback of a flexible object was mechanically reproduced and its effectiveness in VR was proven. ElaStick has succeeded in implementing a novel mechanism to recreate the dynamic response of flexible objects that mimic real ones, suggesting a new category of haptic feedback that can be provided in VR,” explained Professor Bianchi.
The team plans to extend the ElaStick’s applications, from being used merely as a game controller to driving simulations, medical training, and many other digital contexts. This research, led by MS candidate Neung Ryu, won the Best Paper Award at the ACM UIST 2020 (the ACM Symposium on User Interface Software & Technology) last month.
-ProfileProfessor Andrea BianchiMakinteract.kaist.ac.krDepartment of Industrial DesignKAIST
2020.11.23 View 8041