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Humicotta Wins the Silver Prize at the 2017 IDEA
The 3D-printed ceramic humidifier made by the research team led by Professor Sang-Min Bae won the silver prize at the 2017 International Design Excellence Awards (IDEA). Professor Bae’s ID+IM team was also listed as winners of three more appropriate technology designs at the IDEA. The awards, sponsored by the Industrial Designers Society of America, are one of the three prestigious design awards including the Red Dot Design Award and the iF Design Award in Germany.
The silver prize winner in the category of home and bath, Humicotta is an energy-efficient, bacteria free, and easy to clean humidifier. It includes a base module and filter. The base is a cylindrical pedestal with a built-in fan on which the filter is placed. The filter is a 3D-printed honeycomb structure made of diatomite. When water is added, the honeycomb structure and porous terracotta maximize natural humidification. It also offers an open platform service that customizes the filters or provides files that users can use their own 3D printer.
Professor Bae’s team has worked on philanthropy design using appropriate technology as their main topic for years. Their designs have been recognized at prestigious global design awards events, winning more than 50 prizes with innovative designs made for addressing various global and social problems.
The Light Funnel is a novel type of lighting device designed for off-grid areas of Africa. It helps to maximize the natural light effect in the daytime without any drastic home renovations. It consists of a transparent acrylic sphere and a reflective pathway. After filling the acrylic sphere with water and placing it on a rooftop, sunlight passes into the house through the water inside the sphere. It provides a lighted environment nine times brighter than without it. Also, once installed, it can be used almost permanently.
The Maasai Smart Cane is made using wood sticks purchased through fair trade with the Maasai tribe. GPS is installed into the grip of the birch-tree cane, so that cane users can send a signal when in an emergency situation. All of the proceeds of this product go to the tribe.
S.Cone is a first aid kit made in collaboration with Samsung Fire and Marine Insurance. The traffic cone-shaped kit is designed to help users handle an emergency situation intact and safe. The S.Cone has unique versions for fires, car accidents, and marine accidents. For example, the S.Cone for fires is equipped with a small fire extinguisher, smoke mask, and fire blanket. The cap of the S.Cone also functions as an IoT station connecting the fire and gas detector with smart phones.
Professor Bae said of his team’s winning design products, “By making the data public, any person can design their own humidifier if they have access to a 3D-printer. We want it to be a very accessible product for the public. The Light Funnel and Maasai Smart Cane are designed for economically-marginalized populations and the elderly. We will continue to make the best designed products serving the marginalized 90% of the population around the world.”
2017.09.14 View 28680 -
A Novel and Practical Fab-route for Superomniphobic Liquid-free Surfaces
(clockwise from left: Jaeho Choi, Hee Tak Kim, Shin-Hyun Kim)
A joint research team led by Professor Hee Tak Kim and Shin-Hyun Kim in the Department of Chemical and Biomolecular Engineering at KAIST developed a fabrication technology that can inexpensively produce surfaces capable of repelling liquids, including water and oil.
The team used the photofluidization of azobenzene molecule-containing polymers to generate a superomniphobic surface which can be applied for developing stain-free fabrics, non-biofouling medical tubing, and corrosion-free surfaces.
Mushroom-shaped surface textures, also called doubly re-entrant structures, are known to be the most effective surface structure that enhances resistance against liquid invasion, thereby exhibiting superior superomniphobic property.
However, the existing procedures for their fabrication are highly delicate, time-consuming, and costly. Moreover, the materials required for the fabrication are restricted to an inflexible and expensive silicon wafer, which limits the practical use of the surface.
To overcome such limitations, the research team used a different approach to fabricate the re-entrant structures called localized photofludization by using the peculiar optical phenomenon of azobenzene molecule-containing polymers (referred to as azopolymers). It is a phenomenon where an azopolymer becomes fluidized under irradiation, and the fluidization takes place locally within the thin surface layer of the azopolymer.
With this novel approach, the team facilitated the localized photofluidization in the top surface layer of azopolymer cylindrical posts, successfully reconfiguring the cylindrical posts to doubly re-entrant geometry while the fluidized thin top surface of an azopolymer is flowing down.
The structure developed by the team exhibits a superior superomniphobic property even for liquids infiltrating the surface immediately.
Moreover, the superomniphobic property can be maintained on a curved target surface because its surficial materials are based on high molecules.
Furthermore, the fabrication procedure of the structure is highly reproducible and scalable, providing a practical route to creating robust omniphobic surfaces.
Professor Hee Tak Kim said, “Not only does the novel photo-fluidization technology in this study produce superior superomniphobic surfaces, but it also possesses many practical advantages in terms of fab-procedures and material flexibility; therefore, it could greatly contribute to real uses in diverse applications.”
Professor Shin-Hyun Kim added, “The designed doubly re-entrant geometry in this study was inspired by the skin structure of springtails, insects dwelling in soil that breathe through their skin. As I carried out this research, I once again realized that humans can learn from nature to create new engineering designs.”
The paper (Jaeho Choi as a first author) was published in ACS Nano, an international journal for Nano-technology, in August.
(Schematic diagram of mushroom-shaped structure fabrication)
(SEM image of mushroom-shaped structure)
(Image of superomniphobic property of different types of liquid)
2017.09.08 View 8239 -
KAIST to Open the Meditation Research Center
KAIST announced that it will open its Meditation Research Center next June. The center will serve as a place for the wellness of KAIST community as well as for furthering the cognitive sciences and its relevant convergence studies.
For facilitating the center, KAIST signed an MOU with the Foundation Academia Platonica in Seoul, an academy working for enriching the humanities and insight meditation on Aug.31. The Venerable Misan, a Buddhist monk well-known for his ‘Heart Smile Meditation’ program, will head the center.
The center will also conduct convergence research on meditation, which will translate into brain imaging, cognitive behavior, and its psychological effects. Built upon the research, the center expects to publish textbooks on meditation and will distribute them to the public and schools in an effort to widely disseminate the benefits of meditation.
As mindful meditation has become mainstream and more extensively studied, growing evidence suggests multiple psychological and physical benefits of these mindfulness exercises as well as for similar practices. Mind-body practices like meditation have been shown to reduce the body’s stress response by strengthening the relaxation response and lowering stress hormones.
The Venerable Misan, a Ph.D in philosophy from Oxford University, also serves as the director of the Sangdo Meditation Center and a professor at Joong-Ang Sangha University, a higher educational institution for Buddhist monks.
Monk Misan said that meditation will play a crucial part in educating creative students with an empathetic mindset. He added, “Hi-tech companies in Silicon Valley such as Google and Intel have long introduced meditation programs for stress management. Such practices will enhance the wellness of employees as well as their working efficiency.”
President Sung-Chul Shin said of the opening of the center, “From long ago, many universities in foreign countries including Havard, Stanford, Oxfor universities and the Max Planck Institute in Germany have applied scientific approaches to meditation and installed meditation centers. I am pleased to open our own center next year and I believe that it will bring more diverse opportunities for advancing convergent studies in AI and cognitive sciences.
2017.08.31 View 7050 -
Professor Dan Keun Sung Endows Scholarship in Honor of His Retirement
Professor Dan Keun Sung in the School of Electrical Engineering contributed a 100 million KRW scholarship fund this month to KAIST to mark his retirement after more than three decades of work.
“As my retirement date comes closer, I have been thinking about what I could do for the school. I wanted to leave something behind, even though it’s small, for my lifelong school and students. I am hoping that this scholarship fund will benefit the members of KAIST.”
This isn’t his first time making a donation to KAIST. In 2013, Professor Sung donated ten million KRW, which was his cash prize from the 9th Haedong Academic Award of The Korean Institute of Communications and Information Sciences (KICS). At that time, Professor Sung had the chance to create a scholarship fund in his name; however, he wanted to highlight that the scholarship fund was for ‘someone,’ not created by ‘someone.’ In that sense, his scholarship fund was created with no name to benefit students in the School of Electrical Engineering. His colleagues and students supported his idea. Professor Seonghwan Cho, students, and alumni also participated in fund raising efforts, which reached 55 million KRW in total.
Professor Sung emphasized, “Donations should always be remembered, no matter how small they are.” He then explained his purpose for creating the scholarship fund by saying, “Fundraising can be truly meaningful to contributors, knowing that their money is going to supporting the school and students.”
Professor Sung, a fellow of the Institute of Electrical and Electronics Engineers (IEEE) Communication Society, started his post at KAIST in 1986. For the past 30 years, he has devoted himself to fostering young scholars and studying in the area of information and communication. He also participated in developing technologies for the resource management of various future cellular components, such as satellites, switchboards, and signaling networks.
2017.08.11 View 10539 -
Innovative Nanosensor for Disease Diagnosis
(Figure 1. Sensing Device)
(Figure 2. Protein templating route)
Breath pattern recognition is a futuristic diagnostic platform. Simple characterizing target gas concentrations of human exhaled breath will lead to diagnose of the disease as well as physical condition.
A research group under Prof. Il-Doo Kim in the Department of Materials Science has developed diagnostic sensors using protein-encapsulated nanocatalysts, which can diagnose certain diseases by analyzing human exhaled breath. This technology enables early monitoring of various diseases through pattern recognition of biomarker gases related to diseases in human exhalation.
The protein-templated catalyst synthesis route is very simple and versatile for producing not only a single component of catalytic nanoparticles, but also diverse heterogeneous intermetallic catalysts with sizes less than 3 nm. The research team has developed ever more sensitive and selective chemiresistive sensors that can potentially diagnose specific diseases by analyzing exhaled breath gases.
The results of this study, which were contributed by Dr. Sang-Joon Kim and Dr. Seon-Jin Choi as first authors were selected as the cover-featured article in the July issue of 'Accounts of Chemical Research,' an international journal of the American Chemical Society.
In human breath, diverse components are found including water vapor, hydrogen, acetone, toluene, ammonia, hydrogen sulfide, and carbon monoxide, which are more excessively exhaled from patients. Some of these components are closely related to diseases such as asthma, lung cancer, type 1 diabetes mellitus, and halitosis.
Breath analysis for disease diagnosis started from capturing exhaled breaths in a Tedlar bag and subsequently the captured breath gases were injected into a miniaturized sensor system, similar to an alcohol detector. It is possible to analyze exhaled breath very rapidly with a simple analyzing process. The breath analysis can detect trace changes in exhaled breath components, which contribute to early diagnosis of diseases.
However, technological advances are needed to accurately analyze gases in the breath, which occur at very low levels, from 1 ppb to 1 ppm. In particular, it has been a critical challenge for chemiresistive type chemical sensors to selectively detect specific biomarkers in thousands of interfering gases including humid vapor.
Conventionally, noble metallic catalysts such as platinum and palladium have been functionalized onto metal oxide sensing layers. However, the gas sensitivity was not enough to detect ppb-levels of biomarker species in exhaled breath.
To overcome the current limitations, the research team utilized nanoscale protein (apoferritin) in animals as sacrificial templates. The protein templates possess hollow nanocages at the core site and various alloy catalytic nanoparticles can be encapsulated inside the protein nanocages.
The protein nanocages are advantageous because a nearly unlimited number of material compositions in the periodic table can be assembled for the synthesis of heterogeneous catalytic nanoparticles. In addition, intermetallic nanocatalysts with a controlled atomic ratio of two different elements can be achieved using the protein nanocages, which is an innovative strategy for finding new types of catalysts. For example, highly efficient platinum-based catalysts can be synthesized, such as platinum-palladium (PtPd), platinum-nickel (PtNi), platinum-ruthenium (PtRu), and platinum-yttrium (PtY).
The research team developed outstanding sensing layers consisting of metal oxide nanofibers functionalized by the heterogeneous catalysts with large and highly-porous surface areas, which are especially optimized for selective detection of specific biomarkers. The biomarker sensing performance was improved approximately 3~4-fold as compared to the conventional single component of platinum and palladium catalysts-loaded nanofiber sensors. In particular, 100-fold resistance transitions toward acetone (1 ppm) and hydrogen sulfide (1 ppm) were observed in exhaled breath sensors using the heterogeneous nanocatalysts, which is the best performance ever reported in literature.
The research team developed a disease diagnosis platform that recognizes individual breathing patterns by using a multiple sensor array system with diverse sensing layers and heterogeneous catalysts, so that the people can easily identify health abnormalities. Using a 16-sensor array system, physical conditions can be continuously monitored by analyzing concentration changes of biomarkers in exhaled breath gases.
Prof. Kim said, “New types of heterogeneous nanocatalysts were synthesized using protein templates with sizes around 2 nm and functionalized on various metal oxide nanofiber sensing layers. The established sensing libraries can detect biomarker species with high sensitivity and selectivity.” He added, “the new and innovative breath gas analysis platform will be very helpful for reducing medical expenditures and continuous monitoring of physical conditions”
Patents related to this technology were licensed to two companies in March and June this year.
2017.07.19 View 11481 -
Professor Nam Jin Cho Selected as the Eugene P. Wigner Reactor Physicist Awardee
Professor Nam Jin Cho from the Department of Nuclear & Quantum Engineering was selected as the recipient of the 2017 ‘Eugene P. Wigner Reactor Physicist Award.’ The award, established in 1990 by the American Nuclear Society, honors individuals who have made outstanding contributions to the advancement of the field of reactor physics. The award is named after the late Eugene P. Wigner, a pioneer who helped nurture the nuclear age to technical maturity with his pioneering leadership in reactor design.
Professor Cho was recognized for his outstanding leadership and achievement in the field of nuclear physics, especially with his original research in analytic function expansion nodal methods, coarse-mesh angular dependent rebalance methods, and neutron transport calculations. A fellow of the ANS, Professor Cho is the first awardee from the Asian region.
Professor Cho gave all the credit to his colleagues and students at KAIST who have spared no effort while working together for three decades. “I am very grateful for the unique academic ambience which made this challenging work possible as well as the government’s continuing funding at the National Research Laboratory project.
2017.07.12 View 8517 -
Professor Poong Hyun Seong Selected as Fellow of the ANS
Professor Poong Hyun Seong of the Department of Nuclear and Quantum Engineering was selected as a fellow of the American Nuclear Society.
The selection was announced at their annual meeting held in San Francisco on June 12, in recognition of Professor Seong's contributions to the field of nuclear instrumentation, control andhuman factors engineering.
Founded in 1954, the American Nuclear Society selects scholars who have made outstanding achievements and contributions to the development of the nuclear engineering field each year.
Professor Seong's researches in the field of nuclear instrumentation, control and human factors engineering have contributed to the safe operation of nuclear power plants, to the development of systems to maintain nuclear power plants safely in the event of emergency and to the enhancement of effective response capabilities of nuclear power plant operators. His researches significantly contributed to the safety improvement of nuclear power plants and have been recognized worldwide.
Professor Seong said, "Korea has emerged as a nuclear powerhouse. I think not only my academic career but our national reputation in the field of nuclear research has been well recognized by our global peers.” Professor Seong has served as president of the Korean Nuclear Society, editor in chief of Nuclear Engineering and Technology, and as a commissioner of the Korean Nuclear Safety Commission. He is currently working as a commissioner of the Korean Atomic Energy Commission.
2017.06.29 View 8978 -
2017 World Friends ICT KAIST Sets Off to Ethiopia, Tanzania
KAIST launched the ‘2017 World Friends ICT KAIST’ on 21 June at a ceremony held at the Faculty Club. The event was attended by 40 student volunteers and faculty members including President Sung-Chul Shin and student volunteers.
The ‘2017 World Friends ICT KAIST’ is an oversees volunteer program aimed at providing ICT education for students from developing countries and for cultural exchange. The program was organized by the KAIST Leadership Center and sponsored by the National Information Agency (NIA) since 2015.
President Sung-Chul Shin delivered words of encouragement to start the opening ceremony, followed by an oath-taking by the volunteer group, safety training, and a commemorative photoshoot. This year’s World Friends ICT volunteer group consisted of 32 students and 2 staff members to lead and to support the team.
The group was divided into eight teams including APP-frica, KAI-Tigers, and WITH (4 members per team) to volunteer in Addis Ababa Institute of Technology (AAIT) and Adama Science and Technology University in Ethiopia (ASTU), as well as Nelson Mandela African Institute of Science and Technology (NM-AIST) in Tanzania. The teams will educate local students on ICT and promote cultural exchanges. The volunteer period is from July 7 to August 5, lasting about a month.
KAIST conducted primary document examinations and interviews from April 27 to May 18 on volunteer candidates who registered to take part, and selected 32 student volunteers. A total of 68 students registered to volunteer, resulting in a 1:2.1 competition rate.
The volunteering program was customized to the local needs of Ethiopia and Tanzania and thus consisted of ICT education, cultural exchanges, volunteering at farms on the weekends, and science experiments. The area with the most focus by the volunteer team is ICT education, which accounts for 70% of the total volunteer activities. The aim is to educate Ethiopian students at AAIT and ASTU on Windows, MS Office, Adobe Photoshop, and using smartphones. In Tanzania, the team is to volunteer with students of NM-AIST to provide ICT application education such as water tank control using appropriate technology and Arduino to local high school students.
The team is also planning to promote cultural exchanges by preparing K-Pop dancing, traditional Korean games such as Korean shuttlecock game (jegichagi) and Korean wrestling (ssireum), traditional cooking such as bibimbab and half-moon-shaped rice cake (songpyeon), and teaching the Korean language, as well as preparing cultural performances with local university students. On the weekends, the team will visit local farms to volunteer, and local elementary schools and orphanages to conduct science experiments for children, as well as physical education and art activities.
(Photo caption: Volunteers poses with faculty and staff members including President Sung-Chul Shin at a ceremony on June 21.)
2017.06.29 View 12594 -
Top 10 Emerging Technologies of 2017
The World Economic Forum’s Expert Network and Global Future Councils in collaboration with Scientific American and its Board of Advisors announced the top 10 emerging technologies of 2017 on June 26 in Dalian, China where the 2017 Summer Davos Forum is being held. Each technology was chosen for its potential to improve lives, transform industries, and safeguard the planet.
The KAIST delegation, headed by President Sung-Chul Shin, is participating in the forum’s diverse activities including IdeasLab and GULF (Global University Leaders Forum). KAIST is the only Korean representative participating in the IdeasLab. KAIST Distinguished Professor Sang Yup Lee of the Department of Chemical and Biomolecular Engineering, director of KAIST Institute, has served as a committee member of the Global Agenda Council on Emerging Technologies since 2012 and Global Future Council on the Fourth Industrial Revolution. He also chairs the Global Future Council on Biotechnologies.
Professor Lee said, “Very diverse technological breakthroughs were proposed for the final list of candidates. We made the final selections through very in-depth discussion with experts in each field.
We focused on the technologies which have a level of maturity that will enable them to be adopted widely within three to five years."
The top 10 emerging technologies are
(courtesy from https://
www.weforum.org/agenda/2017/06/these-are-the-top-10-emerging-technologies-of-2017):
2017 10대 기술.
1. Liquid biopsies
Liquid biopsies mark a step forward in the fight against cancer. First, they are an alternative where traditional tissue-based biopsies are not possible. Second, they provide a full spectrum of information compared to tissue samples, which only reflect the information available in the sample. Lastly, by homing in on circulating-tumor DNA (ctDNA), genetic material that routinely finds its way from cancer cells into the bloodstream, disease progression or resistance to treatment can be spotted much faster than otherwise relying on symptoms or imaging.
2. Harvesting clean water from air
The ability to extract clean water from air is not new, however existing techniques require high moisture levels and a lot of electricity. This is changing. A team from MIT and University of California, Berkeley has successfully tested a process using porous crystals that convert the water using no energy at all.
3. Deep learning for visual tasks
Computers are beginning to recognize images better than humans. Thanks to deep learning, an emerging field of artificial intelligence, computer-vision technologies are increasingly being used in applications as diverse as driving autonomous vehicles, medical diagnostics, damage assessment for insurance claims, and monitoring water levels and crop yield.
4. Liquid fuels from sunshine
Can we mimic the humble leaf to create artificial photosynthesis to generate and store energy? The prospects are looking increasingly positive. The answer lies in using sunlight-activated catalysts to split water molecules into water and hydrogen, and then using the same hydrogen to convert CO2 into hydrocarbons.
5. The Human Cell Atlas
An international collaboration aimed at deciphering the human body, called the Human Cell Atlas, was launched in October 2016. The project aims to identify every cell type in every tissue; learn exactly which genes, proteins, and other molecules are active in each type, and the processes which control that activity.
6. Precision farming
The Fourth Industrial Revolution is providing farmers with a new set of tools to boost crop yield and quality while reducing water and chemical use. Sensors, robots, GPS, mapping tools, and data-analytics software are all being used to customize the care that plants need.
7. Affordable catalysts for green vehicles
Progress is being made on a promising zero-emission technology, the hydrogen-fed fuel cell. Progress to date has been stymied by the high price of catalysts which contain platinum. However, much progress has been made in reducing reliance on this rare and expensive metal, and the latest developments involve catalysts that include no platinum, or in some cases no metal at all.
8. Genomic vaccines
Vaccines based on genes are superior to more conventional ones in a number of ways. They are faster to manufacture, which is crucial during violent outbreaks. Compared to manufacturing proteins in cell cultures or eggs, producing genetic material should also be simpler and less expensive.
9. Sustainable design of communities
Applying green construction to multiple buildings at once has the potential to revolutionize the amount of energy and water we consume. Sending locally-generated solar power to a smart microgrid could reduce electricity consumption by half and reduce carbon emissions to zero if a project currently under development at the University of California at Berkeley goes according to plan.
10. Quantum computing
Quantum computers’ almost limitless potential has only ever been matched by the difficulty and cost of their construction. This explains why today the small ones that have been built have not yet managed to exceed the power of supercomputers. But progress is being made and in 2016 the technology firm IBM provided public access to the first quantum computer in the cloud.
2017.06.28 View 13995 -
Augmented Reality Application for Smart Tour
‘K-Culture Time Machine,’ an augmented and virtual reality application will create a new way to take a tour. Prof. Woon-taek Woo's research team of Graduate School of Culture Technology of KAIST developed AR/VR application for smart tourism.
The 'K-Culture Time Machine' application (iOS App Store app name: KCTM) was launched on iOS App Store in Korea on May 22 as a pilot service that is targetting the Changdeokgung Palace of Seoul.
The application provides remote experience over time and space for cultural heritage or relics thorough wearable 360-degree video. Users can remotely experience cultural heritage sites with 360-degree video provided by installing a smartphone in a smartphone HMD device, and can search information on historical figures, places, and events related to cultural heritage. Also, 3D reconstruction of lost cultural heritage can be experienced.
Without using wearable HMD devices, mobile-based cultural heritage guides can be provided based on the vision-based recognition on the cultural heritages. Through the embedded camera in smartphone, the application can identify the heritages and provide related information and contents of the hertages. For example, in Changdeokgung Palace, a user can move inside the Changdeokgung Palace from Donhwa-Gate (the main gate of the Changdeokgung Palace), Injeong-Jeon(main hall), Injeong-Moon (Main gate of Injeong-Jeon), and to Huijeongdang (rest place for the king). Through the 360 degree panoramic image or video, the user can experience the virtual scene of heritages.
The virtual 3D reconstruction of the seungjeongwon (Royal Secretariat) which does not exist at present can be shown of the east side of the Injeong-Jeon The functions can be experienced on a smartphone without a wearable device, and it would be a commercial application that can be utilized in the field once the augmented reality function which is under development is completed.
Professor Woo and his research team constructed and applied standardized metadata of cultural heritage database and AR/VR contents. Through this standardized metadata, unlike existing applications which are temporarily consumed after development, reusable and interoperable contents can be made.Professor Woo said, "By enhancing the interoperability and reusability of AR contents, we will be able to preoccupy new markets in the field of smart tourism."
The research was conducted through the joint work with Post Media (CEO Hong Seung-mo) in the CT R&D project of the Ministry of Culture, Sports and Tourism of Korea. The results of the research will be announced through the HCI International 2017 conference in Canada this July.
Figure 1. 360 degree panorama image / video function screen of 'K-Culture Time Machine'. Smartphone HMD allows users to freely experience various cultural sites remotely.
Figure 2. 'K-Culture Time Machine' mobile augmented reality function screen. By analyzing the location of the user and the screen viewed through the camera, information related to the cultural heritage are provided to enhance the user experience.
Figure 3. The concept of 360-degree panoramic video-based VR service of "K-Culture Time Machine", a wearable application supporting smart tour of the historical sites. Through the smartphone HMD, a user can remotely experience cultural heritage sites and 3D reconstruction of cultural heritage that does not currently exist.
2017.05.30 View 12547 -
Controlling 3D Behavior of Biological Cells Using Laser Holographic Techniques
A research team led by Professor YongKeun Park of the Physics Department at KAIST has developed an optical manipulation technique that can freely control the position, orientation, and shape of microscopic samples having complex shapes. The study has been published online in Nature Communications on May 22.
Conventional optical manipulation techniques called “optical tweezers,” have been used as an invaluable tool for exerting micro-scale force on microscopic particles and manipulating three-dimensional (3-D) positions of particles. Optical tweezers employ a tightly-focused laser whose beam diameter is smaller than one micrometer (1/100 of hair thickness), which can generate attractive force on neighboring microscopic particles moving toward the beam focus. Controlling the positions of the beam focus enabled researchers to hold the particles and move them freely to other locations so they coined the name “optical tweezers,” and have been widely used in various fields of physical and biological studies.
So far, most experiments using optical tweezers have been conducted for trapping spherical particles because physical principles can easily predict optical forces and the responding motion of microspheres. For trapping objects having complicated shapes, however, conventional optical tweezers induce unstable motion of such particles, and controllable orientation of such objects is limited, which hinder controlling the 3-D motion of microscopic objects having complex shapes such as living cells.
The research team has developed a new optical manipulation technique that can trap complex objects of arbitrary shapes. This technique first measures 3-D structures of an object in real time using a 3-D holographic microscope, which shares the same physical principle of X-Ray CT imaging. Based on the measured 3-D shape of the object, the researchers precisely calculates the shape of light that can stably control the object. When the shape of light is the same as the shape of the object, the energy of the object is minimized, which provides the stable trapping of the object having the complicated shape.
Moreover, by controlling the shape of light to have various positions, directions, and shapes of objects, it is possible to freely control the 3-D motion of the object and make the object have a desired shape. This process resembles the generation of a mold for casting a statue having desired shape so the researchers coined the name of the present technique “tomographic mold for optical trapping (TOMOTRAP).” The team succeeded in trapping individual human red blood cells stably, rotating them with desired orientations, folding them in an L-shape, and assembling two red blood cells together to form a new structure. In addition, colon cancer cells having a complex structure could be stably trapped and rotated at desired orientations. All of which have been difficult to be realized by the conventional optical techniques.
Professor Park said, “Our technique has the advantage of controlling the 3-D motion of complex shaped objects without knowing prior information about their shape and optical characteristics, and can be applied in various fields including physics, optics, nanotechnology, and medical science.”
Dr. Kyoohyun Kim, the lead author of this paper, noted that this technique can induce controlled deformation of biological cells with desired shapes. “This approach can be also applied to real-time monitoring of surgical prognosis of cellular-level surgeries for capturing and deforming cells as well as subcellular organelles,” added Kim.
Figure 1. Concept of optical manipulation techniques
Figure 2. Experimental setup
Figure 3. Research results
2017.05.25 View 9475 -
Total Synthesis of Flueggenine C via an Accelerated Intermolecular Rauhut-Currier Reaction
The first total synthesis of dimeric securinega alkaloid (-)-flueggenine C was completed via an accelerated intermolecular Rauhut–Currier (RC) reaction. The research team led by Professor Sunkyu Han in the Department of Chemistry succeeded in synthesizing the natural product by reinventing the conventional RC reaction.
The total synthesis of natural products refers to the process of synthesizing secondary metabolites isolated from living organisms in the laboratory through a series of chemical reactions. Each stage of chemical reaction needs to be successful to produce the final target molecule, and thus the process requires high levels of patience and creativity. For that reason, the researchers working on natural products total synthesis are often called “molecular artists”.
Despite numerous reports on the total synthesis of monomeric securinegas, the synthesis of dimeric securinegas, whose monomeric units are connected by a putative enzymatic RC reaction, has not been reported to date.
The team used a Rauhut-Currier (RC) reaction, a carboncarbon bond forming a reaction between two Michael acceptors first reported by Rauhut and Currier in 1963, to successfully synthesize a dimeric natural product, flueggenine C. This new work featured the first application of an intermolecular RC reaction in total synthesis.
The conventional intermolecular RC reaction was driven non-selectively by a toxic nucleophilic catalyst at a high temperature of over 150°C and a highly concentrated reaction mixture, and thus has never been applied to natural products total synthesis. To overcome this long-standing problem, the research team placed a nucleophilic moiety at the γ-position of the enone derivative. As a result, the RC reaction could be induced by the simple addition of a base at ambient temperature and dilute solution, without the need of a nucleophilic catalyst. Using this newly discovered reactivity, the team successfully synthesized the natural product (-)-flueggenine C from commercially available amino acid derivative in 12 steps.
Professor Han said, “Our key finding regarding the remarkably improved reactivity and selectivity of the intermolecular RC reaction will serve as a significant stepping stone in allowing this reaction to be considered a practical and reliable chemical tool with broad applicability in natural products, pharmaceuticals, and materials syntheses. ”
This research was led by Ph.D. candidate Sangbin Jeon and was published in The Journal of the American Chemical Society (JACS) on May 10. This research was funded by KAIST start-up funds, HRHR (High-Risk High-Return), RED&B (Research, Education, Development & Business) projects, the National Research Foundation of Korea, and the Institute for Basic Science.
(Figure 1: Representative dimeric/oligomeric securinega alkaloids)
(Figure 2: Our reinvented Rauhut-Currier reaction)
(Figure 3: Total Synthesis of (-)-flueggenine C)
2017.05.23 View 10439