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En forskargrupp i Korea har utvecklat ett material som potentiellt kan ersätta färgskiftande bläck i förebyggande av förfalskning av sedlar, ID-kort, och så vidare. Ett team lett av Sang-seok Lee från Functional Composite Material Research Center vid Korea Institute of Science and Technology (KIST) meddelade att man framgångsrikt har utvecklat en teknik för att fabricera flytande kristaller som består av flera lager med en tjocklek jämförbar med en hårslinga med hydrofila och hydrofoba egenskaper genom en gemensam studie med ett team lett av Kim Shin-Hyun , professor i kemi- och biomolekylär teknik vid Korea Advanced Institute of Science and Technology (KAIST).
When a special additive called chiral dopant is mixed with the liquid crystal material commonly used in display devices, the liquid crystal molecules rotate spontaneously to form a spiral structure. This is referred to as ”cholesteric liquid crystal,” an photonic crystal material that can exhibit color, without the addition of pigments, by selectively reflecting light of certain wavelengths due to its periodic nanostructure. Also, the light has a circular polarization property in that it rotates in only one direction, and by using this property, it is possible to make colors appear and disappear by changing certain polarization conditions.
If this liquid crystal structure is repeated, it is possible to make a material that can exhibit two or more different characteristics at the same time. Liquid crystals with diverse optical characteristics from having multiple layers, for example, can be used as a material to prevent counterfeiting. However, to make such material consisting of several layers, there is a need to build each layer on top of the one before in a repeated fashion using a elaborately designed device, and there was a need to develop the technology for this complex process.
The KIST-KAIST research team added a cosolvent that dissolved in both oil and water as a way to mix organic alcohol, a hydrophilic moisturizing agent, and the hydrophobic liquid crystal material for all three substances to become evenly mixed together. Then, the mixture was emulsified in water to form microemulsion drops. With the exchanges occurring among the cosolvent, moisturizing agent, and water molecules through the surfaces of the emulsion drops, this resulted in a separation of the hydrophobic and hydrophilic layers.
Depending on the initial mixing ratio of the substances, they separated into multiple layers ranging from one to five, and these layers could be freely controlled. Also, with the phase separation occurring continually within each emulsion drop, the concentration of the chiral dopant inside the liquid crystals changed, resulting in multiple structural colors. This is a new technology to fabricate liquid crystals of multiple layers through a simple process of emulsifying the mixture that has never before been reported.
”What we’ve developed is a simple method of creating multi-layered liquid crystals and we expect it will serve as the basis for adding unique optical characteristics to materials,” said Lee. ”Based on this new technology, we plan on developing diverse functional particles to develop composite materials.”
Republished courtesy of KIST. Photo: A schematic diagram of multi-layered liquid crystal particles developed by the KIST-KAIST joint research team. Credit: Korea Institue of Science and Technology
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Dear IAI members. For my first President’s message in Identification News, I have decided to share key aspects of my acceptance speech that I presented at the Nashville conference this year. You could read it by adding a French accent in order to feel the original speech!
It is a great honor and a privilege to represent the members of this great organization as the newly elected 100th president of the IAI.
We must be proud of our history. It took boldness to build what has grown to be the largest forensic organization in the world. This boldness should inspire us. It was this boldness that drove our founding fathers to build from scratch this organization that is out to unite the forensic world. It is this boldness that drives our practitioners to do more for the sake of truth and justice. It is this boldness that drives our scientists to make more discoveries and develop innovation for the progress of our field. If I had to identify our opponent in terms of innovation and progress, it would be the fear. The fear of making mistakes, the fear of change, the fear of the unknown. This fear is the opposite of boldness.
During my tenure as your president, I wish to strengthen the new generation of practitioners and scientists with the guidance and wisdom of the elders of the organization. To do this, we will have to show boldness, embrace the borderless philosophy of our younger generation and support international involvement within our large organization! For the elders of our organization, please continue to guide us, to support us, to lead us wisely.
One of my first priorities will be to introduce a new IAI award that will recognize young researchers in forensic identification and acknowledge the effort of those that try to integrate this remarkable field; bringing with them the seeds of innovation and progress. I will present a project to the board at the midyear meeting on this subject.
My second priority will be to put in place a special committee that will assess our IAI Divisions. We need ideas that promote communication, cooperation, engagement, and support among our many Divisions. The result of this committee’s brainstorming will be presented to the Board of Directors so that action can be guaranteed while building a stronger relationship between the parent-body and our Divisions.
Finally, I will utilize my mother-tongue, French, to get in touch with French-speaking non-members and present membership in order to promote our organization. We are lucky to have in the line of vice-presidencies, individuals who will be able to continue this effort on behalf of the international community, highlighting Aldo who speaks Italian, Mingo who speaks Spanish, and many other members who speak different languages, including John Grassel, who speaks the dialect of New England! Forensic science is evolving at breakneck speed. Boldness in our field is about facing reality and rolling up our sleeves, despite the colossal scale of the challenge before us. We have a huge opponent in front of us: fear. The fear of not being able, the fear of making mistakes, the fear of change, the fear of the unknown. This feeling is human, but we must overcome it by opposing it with pride and boldness. This is what will guide your organization through the future! Should you ever have a question, need support, or if you would be interested in being involved with the IAI and you don’t know how…please do not be shy! Talk to me either in French or English and I will do whatever I can to help you.