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Kim, Suyong,Dangol, Manita,Kang, Geonwoo,Lahiji, Shayan F.,Yang, Huisuk,Jang, Mingyu,Ma, Yonghao,Li, Chengguo,Lee, Sang Gon,Kim, Chang Hyun,Choi, Young Wook,Kim, So Jeong,Ryu, Ja Hyun,Baek, Ji Hwoon,K American Chemical Society 2017 Molecular Pharmaceutics Vol.14 No.6
<P>Dissolving microneedle (DMN), a transdermal drug delivery system in which drugs are encapsulated in a biodegradable polymeric microstructure, is designed to dissolve after skin penetration and release the encapsulated drugs into the body. However, because of limited loading capacity of drugs within microsized structures, only a small dosage can be delivered, which is often insufficient for patients. We propose a novel DMN application that combines topical and DMN application simultaneously to improve skin permeation efficiency. Drugs in pretreated topical formulation and encapsulated drugs in DMN patch are delivered into the skin through microchannels created by DMN application, thus greatly increasing the delivered dose. We used 4-n-butylresorcinol to treat human hyper pigmentation and found that sequential application of serum formulation and DMNs was successful. In skin distribution experiments using Alexa Fluor 488 and 568 dyes as model drugs, we confirmed that the pretreated serum formulation was delivered into the skin through microchannels created by the DMNs. In vitro skin permeation and retention experiments confirmed that this novel combined application delivered more 4-n-butylresorcinol into the skin than traditional DMN-only and serum-only applications. Moreover, this combined application showed a higher efficacy in reducing patients' melanin index and hyperpigmented regions compared with the serum-only application. As combined application of DMNs on serum-treated skin can overcome both dose limitations and safety concerns, this novel approach can advance developments in transdermal drug delivery.</P>
A compact and scalable fabrication method for robust thin film composite membranes
Kim, Ji Hoon,Cook, Marcus,Park, Sang Hyun,Moon, Sun Ju,Kim, Jeong F.,Livingston, Andrew G.,Lee, Young Moo The Royal Society of Chemistry 2018 Green chemistry Vol.20 No.8
<P>Membrane-based liquid filtration systems have been highlighted as a key green process engineering platform for process intensification. While these systems have been successfully commercialized in desalination and micro/ultra/nanofiltration, it is yet challenging to expand the limited operating conditions (ambient temperature in an aqueous environment) of the currently available membranes, and to solve the exacerbating environmental burden during the fabrication of polymeric membranes. Herein, a new green and compact fabrication method is proposed for both (i) fabricating a robust membrane that can function beyond the typical operating conditions of conventional membranes and (ii) minimizing waste creation and production time. In this work, contrary to the conventional phase inversion method, a spray-coating technique was employed to fabricate a thin composite membrane with high temperature stability and fast solvent permeability. The proposed compact fabrication method can reduce the carbon footprint and the usage of polymers and solvents more than twofold, and eliminate the time-consuming coagulation and washing steps, both of which generate an enormous amount of solvent-contaminated wastewater (up to 50 billion liters per year). Furthermore, the process used dimethyl sulfoxide to bypass conventional <I>N</I>,<I>N</I>-dimethylformamide and <I>N</I>-methyl-2-pyrrolidone as a green solvent, and can simultaneously fabricate a membrane ready to use within a half-day. The resulting membrane exhibited remarkable stability and performance for the separation of solutes in <I>N</I>,<I>N</I>-dimethylformamide, even at elevated temperatures not feasible with conventional polymeric membranes, and so it is a candidate for potential use in the pharmaceutical and fine chemical industries.</P>
Thermally rearranged polymer membranes for desalination
Kim, Ji Hoon,Park, Sang Hyun,Lee, Moon Joo,Lee, Sang Min,Lee, Won Hyo,Lee, Kang Hyuck,Kang, Na Rae,Jo, Hye Jin,Kim, Jeong F.,Drioli, Enrico,Lee, Young Moo The Royal Society of Chemistry 2016 Energy & environmental science Vol.9 No.3
<P>Herein, we demonstrate thermally rearranged polybenzoxazole-co-imide (TR-PBOI) electrospun nanocomposite membranes for membrane distillation and membrane crystallization applications. We seek to demonstrate that a synergistic combination of TR polymers, porous nanofibrous membranes, and particle coating improves the long-term stability while maintaining high porosity and water flux. The fabricated membranes exhibit an excellent water flux (80 kg m(-2) h(-1)) and NaCl rejection (499.99%) with steady performance over more than 186 hours. In addition, for the first time, controlling the heterogeneous nucleation phenomena in membrane crystallization was clearly demonstrated using TR membrane morphology.</P>
Park, Ji Hyun,Kim, Kyung Ho,Park, Yung Woo,Lagerwall, Jan P. F.,Scalia, Giusy American Chemical Society 2015 Langmuir Vol.31 No.34
<P>The realization of long, aligned molecular wires is a great challenge, and a variety of approaches have been proposed. Interestingly, hexapentyloxytriphenylene (HAT5) discotic liquid crystal molecules, a model system of molecules with flat and aromatic cores, can spontaneously form well-aligned, micrometer long, yet only tens of nanometers thick, nanowires on solid surfaces. We have investigated the formation mechanism of these wires using different solvents with selected characteristics, including chemical structure, boiling point, vapor pressure, and surface tension. When casting frorn toluene and benzene solutions, atomic force microscopy reveals that the discotics spontaneously form very long and thin wires, self-aligning along a common orientation. If instead dodecane or heptane are used, different and in general thicker structures are obtained. The chemical structure of the solvent appears to have a key role, coupling to the liquid crystal self-assembly by allowing solvent molecules to enter the ordered structure if their design matches the core of HATS molecules, thereby guiding the assembly. However, other aspects are also relevant in the assembly, including the nature of the substrate and the rate of solvent evaporation, and these can favor or interfere with the self-assembly into long structures. The use of solvents with aromatic structure is advantageous not only because it affects the geometry of the assembly, promoting long wire formation, but it is also compatible with good quality of the intermolecular order, as suggested by a high anisotropy of the Raman spectra of the nanowires formed from these solvents. Finally, the electrical properties of ordered systems show a clearly higher electrical conductivity compared to the disorganized aggregates.</P>
Jeong, Hae-Young,F. Kim, Ji-Hyun,Park, Hong-Seog Korea Genome Organization 2006 Genomics & informatics Vol.4 No.4
6-Phosphogluconolactonase (6PGL) is one of the key enzymes in the ubiquitous pathways of central carbon metabolism, but bacterial 6PGL had been long known as a missing enzyme even after complete bacterial genome sequence information became available. Although recent experimental characterization suggests that there are two types of 6PGLs (DevB and YbhE), their phylogenetic distribution is severely biased. Here we present that proteins in COG group previously described as 3-oarboxymuconate cyclase (COG2706) are actually the YbhE-type 6PGLs, which are widely distributed in Proteobacteria and Fimicutes. This case exemplifies how erroneous functional description of a member in the reference database commonly used in transitive genome annotation cause systematic problem in the prediction of genes even with universal cellular functions.
IMPROVEMENT IN TUNABILITY AND DIELECTRIC LOSS OF BSTZ FERROELECTRIC THIN FILMS USING POST-ANNEALING
Ha, Jong-Yoon,Kang, Chong-Yun,Choi, Ji-Won,Sim, Sung-Hun,Karmanenko, S. F.,Yoon, Seok-Jin,Kim, Hyun-Jai Taylor Francis 2006 Integrated ferroelectrics Vol.86 No.1
<P> The change in dielectric constant of ferroelectric materials as a function of electric field is the key to wide range of applications such as tunable oscillators, delay lines, and phase shifters. The effect of the post-annealing on the dielectric properties of (Ba0.6Sr0.4)(Ti0.9Zr0.1)O3 (BSTZ) thin films deposited by Pulsed Laser Deposition is studied. BSTZ ferroelectric thin films showed simple cubic perovskite structure having (200) preferred orientation independent on deposition conditions. Preferred orientation slightly increased after post-annealing. With increasing the oxygen pressure, the dielectric loss of ferroelectric thin films decreased due to the oxygen vacancies. The reason why the dielectric constant increased was due to expansion of unit cell volume leading the increase of ion polarizability. The structure of ferroelectric thin film did not change after post-annealing. The grain size, dielectric constant and tunability were increased; however dielectric loss was decreased after annealing. The microstructure of ferroelectric thin film was one of the important facts(stress between thin films and substrates, thermal conductivity etc) effecting the dielectric properties such as dielectric constant, dielectric loss and tunability etc. Microwave dielectric properties of (Ba0.6Sr0.4)(Ti0.9Zr0.1)O3 ferroelectric thin film were obtained at deposition temperature 750°C, oxygen pressure 200 mTorr, and post-annealing conditions 1100°C for 1h: dielectric constant 2060, dielectric loss 0.0026 and tunability 25.3%.</P>
Kim, Kee-Young,Osabutey, Angelina F.,Nguyen, Phuong,Kim, Soo Bae,Jo, You-Young,Kweon, HaeYong,Lee, Hyun-Tai,Ji, Sang-Deok,Koh, Young Ho Korean Society of Sericultural Science 2019 International Journal of Industrial Entomology Vol.39 No.1
Steamed and freeze-dried mature silkworm powder (SMSP) is a natural food containing a large amount of various functional materials and has various health promoting effects. SMSP is known to increase the life expectancy and healthspan, simultaneously. The accomplishment of extension of healthspan should be possible to achieve by activating various signaling pathways delaying aging in various tissues, not by regulating only a few signaling pathways. Consistent with this notion, SMSP increased the resistant to Parkinson disease by enhancing olfaction and mitochondrial activity in neurons of animal models. In addition, SMSP could enhance the gastrointestinal functions. The animals consumed SMSP showed enhanced alcohol metabolisms, reduced cholesterols in bloods, increased resistance to carcinogens causing liver cancers, and protective effects in alcohol induced stomach ulcers. Furthermore, SMSP was also effective in appearance. The SMSP consumed animals showed reduced skin pigmentations and more hair growth compared with control animals. Taken together, the functional enhancement effects of SMSPs in various tissues and organs, which have been discovered to date, are combined to extend healthspan. Therefore, SMSP can be regarded as calorie restriction mimetics. Further studies in the health promoting effects of SMSP will contribute to identifying new applicable diseases, resulted in increased sales of SMSP and incomes of sericulture farmers.