Cells
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Lead-free, Efficient Perovskite for Photovoltaic Cells
(Clockwise from left: Post-doc Researcher Lamjed Debbichi, Master’s Candidate Songju Lee, Professor Min Seok Jang and Professor Hyungjun Kim)
A KAIST research team has proposed a perovskite material, Cs2Au2I6 that serves as a potential active material for highly efficient lead-free thin-film photovoltaic devices. This material is expected to lay the foundation to overcome previously known limitations of perovskite including its stability and toxicity issues.
As strong candidates for next-generation high-efficiency photovoltaic cells, perovskite photovoltaic cells have a maximum photoconversion efficiency of 22%, comparable to high-performance crystalline silicon photovoltaic cells. In addition, perovskite-based cells can be fabricated at low temperatures, thereby bringing about dramatic cost reductions.
However, it has been noted that conventional organic-inorganic hybrid perovskite materials exhibit low stability, eventually degrading their performance and making them unfit for continued use. Moreover, their inclusion of lead has undermined their environmental friendliness.
In light of this, a joint team led by Professor Hyungjun Kim from the KAIST Department of Chemistry and Professor Min Seok Jang from the School of Electrical Engineering has analyzed a previously discovered perovskite material, Cs2Au2I6, consisting of only inorganic substances and investigated its suitability for application in thin-film photovoltaic devices. Theoretical investigations suggests that this new perovskite material is not only as efficient but also more stable and environment friendly compared to the conventional perovskite materials. For this analysis, the team developed multiscale multiphysics simulation frameworks. Atomic-scale first-principle quantum calculations were carried out to study the optical properties of the proposed material, and device-scale electromagnetic simulations were conducted to suggest that the material could indeed serve as a promising photovoltaic substance at the device level.
From this point onward, the research team plans to extend the study in two directions: an empirical study to apply the perovskite material in real-world photovoltaic cells and a theoretical analysis to find the optimal and highly stable material for photovoltaic cells. The team said, “Perovskite materials are highly efficient, but in order to completely replace the conventional solar cells, their stability and toxicity issues must first be resolved.” They added that this research is expected to accelerate related studies in pursuit of high-efficiency, environment-friendly perovskite materials.
This research, led by post-doc researcher Lamjed Debbichi and master’s candidate Songju Lee, was selected as the front cover article of Advanced Materials on March 22.
Figure 1. Cover of Advanced Materials
Figure 2. Schematic of full solar cell device structure
2018.06.08 View 8286 -
Polymers with Highly Improved Light-transformation Efficiency
A joint Korean research team, led by Professor Bum-Joon Kim of the Department of Chemical and Biomolecular Engineering at KAIST and Professor Young-Woo Han of the Department of Nanofusion Engineering at Pusan National University, has developed a new type of electrically-conductive polymer for solar batteries with an improved light-transformation efficiency of up to 5%. The team considers it a viable replacement for existing plastic batteries for solar power which is viewed as the energy source of the future.
Polymer solar cells have greater structural stability and heat resistance compared to fullerene organic solar cells. However, they have lower light-transformation efficiency—below 4%—compared to 10% of the latter. The low efficiency is due to the failure of blending among the polymers that compose the active layer of the cell. This phenomenon deters the formation and movement of electrons and thus lowers light-transformation efficiency.
By manipulating the structure and concentration of conductive polymers, the team was able to effectively increase the polymer blending and increase light-transformation efficiency. The team was able to maximize the efficiency up to 6% which is the highest reported ratio.
Professor Kim said, “This research demonstrates that conductive polymer plastics can be used widely for solar cells and batteries for mobile devices.”
The research findings were published in the February 18th issue of the Journal of the American Chemical Society (JACS).
Picture: Flexible Solar Cell Polymer Developed by the Research Team
2015.04.05 View 9898 -
Regulatory T Cells Influence Liver Damage of Hepatitis A Patients
Liver damage becomes more severe with the decrease of regulatory T cells
“This research will aid the development of hepatitis A targeted drug,” said a KAIST researcher.
The KAIST Graduate School of Medical Science and Engineering’s Professor Eui-Cheol Shin and his research team have identified the mechanism, explaining how the regulatory T cells are responsible for the body’s immune system and how they have induced liver damage of hepatitis A patients.
The research results were published online in the July 9th edition of ‘Gut,’ the world’s most prominent journal in the field of gastroenterology.
Hepatitis A is an acute form of hepatitis caused by hepatitis A virus. The virus spreads through oral contact and enters the body via digestive organs.
Regulatory T cells play an important role in maintaining the homeostasis of the body’s immune system by inhibiting the activation of other immune cells. In the case of chronic viral infections, regulatory T cells are known to contribute to the duration of the infection, weakening the immune response to virus infections. However, there has been no information on what roles the regulatory T cells perform in the case of acute viral infections.
The research team used the fluorescence flow cytometry technique to determine the number and characteristics of a variety of immune cells, including regulatory T cells, in the blood of hepatitis A patients.
Consequently, the researchers confirmed that the decrease in the regulatory T cells immune inhibitory ability was consistent with a significant reduction in the number of regulatory T cells in the blood of hepatitis A patients. Furthermore, it was identified that the more noticeable decrease of regulatory T cells led to the occurrence of a more severe liver injury.
The analysis of hepatitis A patient’s blood proved that the cause of the decrease in the number and function of regulatory T cells was the increased expression of cell surface protein ‘Fas,’ which induces cell death.
Professor Shin said, “This study is the first case which proposes the mechanism for clinical aspects in not only hepatitis A, but also acute virus infection.” He added on the future prospect of the research that: “In the future, we can prevent tissue damage by inhibiting cell death of regulatory T cells for severe acute viral infections that do not have an effective treatment for the virus itself.”
[Picture]
The picture shows the process of fluorescence flow cytometry technique to study regulatory T cell in the blood of hepatitis A patients.
2014.08.11 View 9612 -
Top Ten Ways Biotechnology Could Improve Our Everyday Life
The Global Agenda Council on Biotechnology, one of the global networks under the World Economic Forum, which is composed of the world’s leading experts in the field of biotechnology, announced on February 25, 2013 that the council has indentified “ten most important biotechnologies” that could help meet rapidly growing demand for energy, food, nutrition, and health. These new technologies, the council said, also have the potential to increase productivity and create new jobs.
“The technologies selected by the members of the Global Agenda Council on Biotechnology represent almost all types of biotechnology.Utilization of waste, personalized medicine,and ocean agricultureare examples of the challenges where biotechnology can offer solutions,”said Sang Yup Lee, Chair of the Global Agenda Council on Biotechnology and Distinguished Professor in the Department of Chemical and Biomolecular Engineering at the Korea Advanced Institute of Science and Technology (KAIST). He also added that “the members of the council concluded that regulatory certainty, public perception, and investment are the key enablers for the growth of biotechnology.”
These ideas will be further explored during “Biotechnology Week” at the World Economic Forum’s Blog (http://wef.ch/blog) from Monday, 25 February, 2013. The full list follows below:
Bio-based sustainable production of chemicals, energy, fuels and materials
Through the last century, human activity has depleted approximately half of the world’s reserves of fossil hydrocarbons. These reserves, which took over 600 million years to accumulate, are non-renewable and their extraction, refining and use contribute significantly to human emissions of greenhouse gases and the warming of our planet. In order to sustain human development going forward, a carbon-neutral alternative must be implemented. The key promising technology is biological synthesis; that is, bio-based production of chemicals, fuels and materials from plants that can be re-grown.
Engineering sustainable food production
The continuing increase in our numbers and affluence are posing growing challenges to the ability of humanity to produce adequate food (as well as feed, and now fuel). Although controversial, modern genetic modification of crops has supported growth in agricultural productivity. In 2011, 16.7 million farmers grew biotechnology-developed crops on almost 400 million acres in 29 countries, 19 of which were developing countries. Properly managed, such crops have the potential to lower both pesticide use and tilling which erodes soil.
Sea-water based bio-processes
Over 70% of the earth surface is covered by seawater, and it is the most abundant water source available on the planet. But we are yet to discover the full potential of it. For example with halliophic bacteria capable of growing in the seawater can be engineered to grow faster and produce useful products including chemicals, fuels and polymeric materials. Ocean agriculture is also a promising technology. It is based on the photosynthetic biomass from the oceans, like macroalgae and microalgae.
Non-resource draining zero waste bio-processing
The sustainable goal of zero waste may become a reality with biotechnology. Waste streams can be processed at bio-refineries and turned into valuable chemicals and fuels, thereby closing the loop of production with no net waste. Advances in biotechnology are now allowing lower cost, less draining inputs to be used, including methane, and waste heat. These advances are simplifying waste streams with the potential to reduce toxicity as well as support their use in other processes, moving society progressively closer to the sustainable goal of zero waste.
Using carbon dioxide as a raw material
Biotechnology is poised to contribute solutions to mitigate the growing threat of rising CO2 levels. Recent advances are rapidly increasing our understanding of how living organisms consume and use CO2. By harnessing the power of these natural biological systems, scientists are engineering a new wave of approaches to convert waste CO2 and C1 molecules into energy, fuels, chemicals, and new materials.
Regenerative medicine
Regenerative medicine has become increasingly important due to both increased longevity and treatment of injury. Tissue engineering based on various bio-materials has been developed to speed up the regenerative medicine. Recently, stem cells, especially the induced pluripotent stem cells (iPS), have provided another great opportunity for regenerative medicine. Combination of tissue engineering and stem cell (including iPS) technologies will allow replacements of damaged or old human organs with functional ones in the near future.
Rapid and precise development and manufacturing of medicine and vaccines
A global pandemic remains one of the most real and serious threats to humanity. Biotechnology has the potential to rapidly identify biological threats, develop and manufacture potential cures. Leading edge biotechnology is now offering the potential to rapidly produce therapeutics and vaccines against virtually any target. These technologies, including messenger therapeutics, targeted immunotherapies, conjugated nanoparticles, and structure-based engineering, have already produced candidates with substantial potential to improve human health globally.
Accurate, fast, cheap, and personalized diagnostics and prognostics
Identification of better targets and combining nanotechnology and information technology it will be possible to develop rapid, accurate, personalized and inexpensive diagnostics and prognostics systems.
Bio-tech improvements to soil and water
Arable land and fresh water are two of the most important, yet limited, resources on earth. Abuse and mis-appropriation have threatened these resources, as the demand on them has increased. Advances in biotechnology have already yielded technologies that can restore the vitality and viability of these resources. A new generation of technologies: bio-remediation, bio-regeneration and bio-augmentation are being developed, offering the potential to not only further restore these resources, but also augment their potential.
Advanced healthcare through genome sequencing
It took more than 13 years and $1.5 billion to sequence the first human genome and today we can sequence a complete human genome in a single day for less than $1,000. When we analyze the roughly 3 billion base pairs in such a sequence we find that we differ from each other in several million of these base pairs. In the vast majority of cases these difference do not cause any issues but in rare cases they cause disease, or susceptibility to disease. Medical research and practice will increasingly be driven by our understanding of such genetic variations together with their phenotypic consequences.
2013.03.19 View 10973 -
Success in differentiating Functional Vascular Progenitor Cells (VPC)
KAIST’s Professor Han Yong Man successfully differentiated vascular progenitor cells from human embryonic stem cells and reversed differentiated stem cells.
The research went beyond the current method of synthesis of embryonic body or mice cell ball culture and used the careful alteration of signal transmission system of the human embryonic stem cells to differentiate the formation of vascular progenitor cells.
The team controlled the MEK/ERK and BMP signal transmission system that serves an important role in the self replication of human embryonic stem cells and successfully differentiated 20% of the cells experimented on to vascular progenitor cells.
The vascular progenitor cells produced with such a method successfully differentiated into cells forming the endodermis of the blood vessel, vascular smooth muscle cells and hematopoietic cells in an environment outside of the human body and also successfully differentiated into blood vessels in nude mice.
In addition, the vascular progenitor cell derived from human embryonic cells successfully formed blood vessels or secreted vascular growth factors and increased the blood flow and the necrosis of blood vessels when injected into an animal with limb ischemic illness.
The research was funded by the Ministry of Education, Science and Technology, 21st Century Frontier Research and Development Institution’s Cell Application Research Department and Professor Ko Kyu Young (KAIST), Professor Choi Chul Hee (KAIST), Professor Jeong Hyung Min (Cha Medical School) and Doctor Jo Lee Sook (Researcher in Korea Bio Engineering Institute) participated in it.
The results of the research was published as the cover paper of the September edition of “Blood (IF:10.55)”, the American Blood Journal and has been patented domestically and has finished registration of foreign PCT.
The results of the experiment opened the possibility of providing a patient specific cure using stem cells in the field of blood vessel illness.
2011.01.18 View 12334 -
KAIST developed a plastic film board less sensitive to heat.
The research result was made the cover of magazine, Advanced Materials and is accredited to paving the way to commercialize flexible display screens and solar power cells.
Transparent plastic and glass cloths, which have a limited thermal expansion needed for the production of flexible display screens and solar power cells, were developed by Korean researchers.
The research, led by KAIST’s Professor Byoung-Soo Bae, was funded by the Engineering Research Center under the initiative of the Ministry of Education, Science and Technology and the National Research Foundation. The research result was printed as the cover paper of ‘Advanced Materials’ which is the leading magazine in the field of materials science.
Professor Bae’s team developed a hybrid material with the same properties as fiber glass. With the material, they created a transparent, plastic film sheet resistant to heat. Transparent plastic film sheets were used by researchers all over the world to develop devices such as flexible displays or solar power cells that can be fit into various living spaces. However, plastic films are heat sensitive and tend to expand as temperature increases, thereby making it difficult to produce displays or solar power cells.
The new transparent, plastic film screen shows that heat expansion index (13ppm/oC) similar to that of glass fiber (9ppm/oC) due to the presence of glass fibers; its heat resistance allows to be used for displays and solar power cells over 250oC.
Professor Bae’s team succeeded in producing a flexible thin plastic film available for use in LCD or AMOLED screens and thin solar power cells.
Professor Bae commented, “Not only the newly developed plastic film has superior qualities, compared to the old models, but also it is cheap to produce, potentially bringing forward the day when flexible displays and solar panels become commonplace. With the cooperation of various industries, research institutes and universities, we will strive to improve the existing design and develop it further.”
2011.01.05 View 12903 -
International Workshop on EEWS 2010 was held.
On October 7 and 8th at Fusion Hall of KI Building, KAIST, the 2010 International Workshop on EEWS (Energy, Environment, Water, and Sustainability) was held.
The third to be held, forty national and international academic professionals including Mark Shannon, professor at University of Illinois at Urbana-Champaign, Domen Kazunari, Tokyo University professor, Dong Sub Kim, CTO of SK Energy and Doyoung Seung, Senior Vice President of GS Caltex, participated at this year’s workshop.
In twelve sessions, themes including Artificial Photosynthesis, Wireless Power Transfer, Green Aviation, Safe Nuclear Fuel Reuse, Fuel Cells in Action, LED 2.0, Foundation of Energy-Water Nexus, and Flexible Battery & Solar Cell were presented and discussed.
“Through this workshop, current EEWS policy and research progress from different countries and the future of related technologies will be foreseen,” said Jae Kyu Lee, Dean of KAIST EEWS Initiative. “I hope it became an opportunity to create cooperative relationships with leading researchers.”
EEWS is a research project conducted by KAIST to solve global issues that mankind faces today such as depletion of energy, environmental pollution, water shortage, and sustainability.
2010.10.15 View 14767
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New drug targeting method for microbial pathogens developed using in silico cell
A ripple effect is expected on the new antibacterial discovery using “in silico” cells
Featured as a journal cover paper of Molecular BioSystems
A research team of Distinguished Professor Sang Yup Lee at KAIST recently constructed an in silico cell of a microbial pathogen that is resistant to antibiotics and developed a new drug targeting method that could effectively disrupt the pathogen"s growth using the in silico cell.
Hyun Uk Kim, a graduate research assistant at the Department of Chemical and Biomolecular Engineering, KAIST, conducted this study as a part of his thesis research, and the study was featured as a journal cover paper in the February issue of Molecular BioSystems this year, published by The Royal Society of Chemistry based in Europe.
It was relatively easy to treat infectious microbes using antibiotics in the past. However, the overdose of antibiotics has caused pathogens to increase their resistance to various antibiotics, and it has become more difficult to cure infectious diseases these days.
A representative microbial pathogen is Acinetobacter baumannaii. Originally isolated from soils and water, this microorganism did not have resistance to antibiotics, and hence it was easy to eradicate them if infected. However, within a decade, this miroorganism has transformed into a dreadful super-bacterium resistant to antibiotics and caused many casualties among the U.S. and French soldiers who were injured from the recent Iraqi war and infected with Acinetobacter baumannaii.
Professor Lee’s group constructed an in silico cell of this A. baumannii by computationally collecting, integrating, and analyzing the biological information of the bacterium, scattered over various databases and literatures, in order to study this organism"s genomic features and system-wide metabolic characteristics. Furthermore, they employed this in silico cell for integrative approaches, including several network analysis and analysis of essential reactions and metabolites, to predict drug targets that effectively disrupt the pathogen"s growth. Final drug targets are the ones that selectively kill pathogens without harming human body.
Here, essential reactions refer to enzymatic reactions required for normal metabolic functioning in organisms, while essential metabolites indicate chemical compounds required in the metabolism for proper functioning, and their removal brings about the effect of simultaneously disrupting their associated enzymes that interact with them.
This study attempted to predict highly reliable drug targets by systematically scanning biological components, including metabolic genes, enzymatic reactions, that constitute an in silico cell in a short period of time.
This research achievement is highly regarded as it, for the first time, systematically scanned essential metabolites for the effective drug targets using the concept of systems biology, and paved the way for a new antibacterial discovery. This study is also expected to contribute to elucidating the infectious mechanism caused by pathogens.
"Although tons of genomic information is poured in at this moment, application research that efficiently converts this preliminary information into actually useful information is still lagged behind. In this regard, this study is meaningful in that medically useful information is generated from the genomic information of Acinetobacter baumannii," says Professor Lee. "In particular, development of this organism"s in silico cell allows generation of new knowledge regarding essential genes and enzymatic reactions under specific conditions," he added.
This study was supported by the Korean Systems Biology Project of the Ministry of Education, Science and Technology, and the patent for the development of in silico cells of microbial pathogens and drug targeting methods has been filed.
[Picture 1 Cells in silico]
[Picture 2 A process of generating drug targets without harming human body while effectively disrupting the growth of a pathogen, after predicting metabolites from in silico cells]
2010.04.05 View 14590
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KAIST Research Team Identified Promising New Source to Obtain Stem Cells
KAIST Research Team Identified Promising New Source to Obtain Stem Cells
A research team at KAIST led by Professor Gou-Young Koh, M.D. and Ph.D., of the Department of Biological Sciences, has found evidence that fat tissue, known as adipose tissue, may be a promising new source of valuable and easy-to-obtain regenerative cells called hematopoietic stem and progenitor cells (HSPCs).
HSPCs are adult stem cells that have the ability to generate and develop into many different kinds of cells. They are now used to repair damaged tissues and are being studied for their potential to treat a vast array of chronic and degenerative conditions such as leukemia. Mostly found in bone marrow but with a limited quantity, HSPCs are hard to cultivate in vitro, thus becoming an obstacle to use them for research and therapeutic purposes.
Within the adipose tissue is a special cell population known as the stromal vascular fraction (SVF), which share similar properties to those in the bone marrow. Cells in the bone marrow and SVF have the ability to differentiate into several cell types. In addition, both adipose and bone marrow offer similar environments for optimal stem cell growth and reproduction.
Given the fact that adipose and bone marrow tissues share similar properties, Dr. Koh and his team conducted a research, injecting granulocyte colony-stimulating factor (G-CSF), a growth hormone used to encourage the development of stem cells, into an adipose tissue of a mouse whose bone marrow is damaged. As a result, the team has found that the SVF derived from adipose tissue contains functional HSPCs capable of generating hematopoietic (blood-forming) cells to repair the damaged bone morrow.
The Ministry of Education, Science and Technology nominated the KAIST research as one of its sponsoring 21st Century Frontier R&D Programs. Director Dong-Wook Kim of Stem Cell Research Center (SCRS) that oversees the KAIST team expressed a possibility to use the adipose tissue as an alternative source to obtain stem cells for regeneration medicine.
Dr. Koh also said, “It’s been a well known method to extract HSPCs from the bone morrow or blood, but it’s the first time to identify adipose tissue, before considered useless, as a new possible supplier for functional and transplantable HSPCs.”
The study results have received an important recognition from the academia—the American Society of Hematology published the research as a main article in its official journal, Blood, for the February 4th, 2010 issue, which is the most citied peer-reviewed publication in the field.
2010.02.05 View 11616
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Prof. Woo's Team Discovers Eco-Friendly Solid-Oxide Fuel Cell System
A KAIST research team led by Prof. Seong-Ihl Woo of the Department of Chemical & Biomolecular Engineering has found a method to use glycerol, a byproduct from the production of biodiesel, as fuel for solid oxide fuel cells (SOFC), university authorities said on Tuesday (Oct. 27).
The research finding shows that glycerol can be an environmentally sustainable fuel when it is used for operating SOFCs with internal reforming, instead of hydrogen and methane. The finding was published in the Oct. 14, 2009 online edition of ChemSusChem, a sister journal of Angewandte Chemie, the world"s leading chemistry journal.
Biodiesel is an attractive alternative energy source because of its low sulfur content and demand is growing worldwide as oil price soars. Bio-derived glycerol will not contribute to the greenhouse effect and has the potential to contribute to reducing global warming.
Currently, glycereol is used as a raw material in the cosmetic, pharmacy, food, and tobacco industries. However, its supply exceeds its demand as the volume of biodiesel production increases. The production of 1 ton of biodiesel produces 0.1 ton of glycerol. Many researchers have investigated various routes for the consumption of surplus glycerol.
The research is expected to contribute to sustainable growth by reducing the emissions of carbon dioxide and reusing generated carbon dioxide for the production of biomass. The new method enables manufacturers to use glycerol as a fuel for operating SOFC.
2009.10.28 View 12277