• Clean Technology
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• v.14 no.4
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• pp.256-264
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• 2008

In this study, using PBAST (poly(butylene adipate-co-succinate-co-terephthalate)) which was eco-friendly biodegradable aliphatic polyester, PBAST/PVA (poly(vinyl alcohol)) double-layered hollow microspheres were prepared with the water/oil/water multiple emulsion ($W_1/O/W_2$) method. The double-layered hollow microspheres were manufactured with the yield of 30.92% when the concentration of polymer PBAST in organic phase was 5 wt%, the concentration of PVA in inner aqueous phase was 5 wt%, the volume ratio of $W_1/O$ emulsion to outer aqueous phase was 1:4.5, and when co-surfactants that had large gap in HLB (hydrophile-lipophile balance) value were used. The bulk density of prepared hollow microsphere was 0.180 g/ml and particle size was $1.5{\sim}3\;{\mu}m$.

• Applied Chemistry for Engineering
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• v.23 no.6
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• pp.539-545
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• 2012

3-(2-benzotriazolovinyl)thiophene (BVT) was synthesized by the connection of the thiophene with the electron-withdrawing group, benzotriazole, through the vinylene. Its structure was confirmed by FT-IR, $^1H$-NMR, $^{13}C$-NMR and 2D hetero-cosy spectroscopy. Both BVT and 3-octylthiophene (OT) were copolymerized and showed an average molecular weight of 12000 (PDI 2.67) and 15000 (PDI 2.55), respectively. The copolymers were dissolved in the organic solvent such as chloroform, THF, TCE, etc. The mole ratios of BVT and OT in the synthesized copolymers were confirmed as 1 : 1.8 and 1 : 2.8 from $^1H$-NMR spectra. The UV-vis maximum absorption of copolymers appeared at the wavelength of 470 nm and 465 nm and the photoluminescence at ${\lambda}_{max}$ = 662 nm and 641 nm correspond to red-orange light. The band gaps of copolymers at 1.96 eV and 2.02 eV were found to be higher than those of poly(3-octylthiophene). The HOMO energy levels of the copolymers decreased overall in comparison with those of poly(3-octylthiophene), but the overall LUMO energy level increased.

• Applied Chemistry for Engineering
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• v.25 no.3
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• pp.233-236
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• 2014

Organic light emitting diodes (OLEDs) received much attention from both academia and industry as the next-generation flat panel displays. However, to produce high quality OLEDs, there are still many challenges to overcome. Especially, in full color OLEDs, the intrinsic wide band gap of the blue emitting materials results in inferior efficiency compared to those of green and red emitting materials. Therefore, extensive research efforts have been devoted to develop efficient blue emitting materials. This review briefly summarizes the basics of OLEDs and introduces highlights of research efforts in blue-emitting materials.

• Journal of the Korean Chemical Society
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• v.36 no.2
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• pp.287-292
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• 1992

The rate constants of the nucleophilic addition reaction of amines (piperidine and diethylamine) to phenylvinylketone in various solvents have been determined by UV spectrophotometry at $25^{\circ}C$. On the basis of the high sensitivity of the rate to the polarity of the medium, it may be concluded that the reaction intermediate has zwitterionic character. The effect of the solvents on the rate of the bimolecular nucleophilic addition reaction is described well by the Kirkwood equation: The transition state of the reaction has a cyclic structure formed through an intramolecular hydrogen bond. The addition reaction of primary and secondary amines to phenylvinylketone in all solvents take place considerably faster than that of tertiary amine and this results also can be explained by the intermediate products in the reaction have a cyclic structure formed through an intramolecular hydrogen bond for the primary and secondary amines but not for the tertiary amine.

• Korean Journal of Plant Taxonomy
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• v.51 no.3
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• pp.181-191
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• 2021

Tulips are bulbous geophytes that have considerable commercial value worldwide. This genus primarily originated in the Tien Shan and Pamir-Alai mountain ranges, which surround the Ferghana Valley. The Ferghana Valley is home to five sections of the genus Tulipa L, represented by 23 taxa (22 species). However, there is a lack of detailed information about the distribution of Tulipa species in the natural geographic area of the Ferghana Valley. Therefore, to address this knowledge gap, we comprehensively investigated the spatial distribution of all Tulipa species in the valley. To assess the spatial distribution, the entire area was divided into 32 squares consisting of four latitudinal and eight longitudinal zones. The results showed that latitudinal zones B and C with 15 and 13 taxa, respectively, along with five longitudinal zones (A5, B3, B4, C2, and C3) with 5 to 10 taxa were hotspots for this genus. Additionally, the spatial distributions of the species in terms of the corresponding state borders, mountain ranges, endemism, and conservation issues were assessed. The findings of this study provide comprehensive information about the distribution of Tulipa species to assist with conservation initiatives ultimately to ensure the survival of various species.

• Journal of the Korean Chemical Society
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• v.63 no.2
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• pp.73-77
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• 2019

We compared methodologies based on the density functional theory (DFT), e.g., time-dependent DFT (TD-DFT), TD-DFT within Tamm-Dancoff approximation (TDA-DFT), and spin-unrestricted DFT (UDFT), that are usually employed to optimize the geometries of ${\pi}$-conjugated molecules in their lowest lying triplet excited ($T_1$) state. As a model system for ${\pi}$-conjugated molecules, we employed 1,2,3,4,5-pentacyano-6-phenyl-benzene. In conjunction with 6-31G(d) basis sets, we made use of gap-tuned range-separated ${\omega}B97X$ functional which is often employed recently in the calculations of molecular excited states. Near the equilibrium geometries, we found that the important difference between the geometries derived at UDFT level and those at TD-DFT or TDA-DFT methods: more stable ground-state energies but higher triplet excitation energies for UDFT derived geometries. In the studies, we discuss such differences in more detail.

• Applied Chemistry for Engineering
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• v.30 no.2
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• pp.254-259
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• 2019

In this study, we synthesized the pine leaf extract intercalated layered Mg-phyllosilicate nanoparticles (PLE/MgP) via one-pot synthesis. MgP was successfully synthesized with the octahedral and tetrahedral structure by XRD analysis and a gap of interlayer distance (d-spacing) between MgP sheets by the intercalation of PLE was confirmed. As a result of the investigation of antimicrobial activity against cutaneous microorganisms by the minimum inhibitory concentration (MIC) and bactericidal concentration (MBC) analyses, the antimicrobial activity of PLE/MgP was more improved than that of MgP or PLE. The prepared sandwich-structured PLE/MgP organic/inorganic hybrid materials will be useful in the field of numerous applications containing cosmetic and biomedical materials.

• Applied Chemistry for Engineering
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• v.33 no.6
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• pp.588-593
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• 2022

The effects of P₂O₅-doped on the surface of MgO particles on hydrolysis, water repellency, and insulation behavior were investigated. P₂O₅-doped MgO has exhibited a unique electrical property, which is significant insulation behavior due to both the suppression of the hydrolysis reaction by P₂O₅ and water repellency. Therefore, the insulation behavior was inversely proportional to the hydrophilicity and the Mg(OH)₂ and OH^-charge transfer ratio by the surface hydration reaction of MgO. The insulation of MgO according to aging was strongly influenced by the surface hydration reaction, the band gap of the added dopant species, and the hydrophilicity and hydrophobicity of the dopant. Finally, it was to show electrical insulation by inhibiting the surface hydration reaction of the hydrophilic MgO, which has a great potential for use in heat transfer medium applications.

• Korean Journal of Medicinal Crop Science
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• v.25 no.2
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• pp.89-94
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• 2017

Background: The purpose of improving the quality of oriental medicinal herbs is to contribute to the improvement of the income of farm. The present study investigated the effect of reasonable drying methods, different storage conditions and packageing materials on quality and stability of Scutellaria baicalensis Georgi and for developing GAP (good agricultural practice) guide book. Methods and Results: Three methods of drying Scutellaria baicalensis roots produced over two years were used to estimate loss rate owing to drying, storage, and packaging. The methods of drying were categorized into natural drying (36 - 60 h by sunshine), drying with heat dryer (2 - 10 h), or drying with gas bulk dryer (2 - 10 h). After cleaning, and initial drying for a few days under controlled temperature conditions, the second phase of drying was carried out at 35, 45 and $55^{\circ}C$. Changes in hunter color values and quality under the two studied storage treatments (at $20^{\circ}C$ indoors and at $4^{\circ}C$ in a refigerator) were evaluated. Storage period for 60, 120, and 180 days in three packaging materials, PE (polyethylene package), PP (polypropylene gunnysack), and WP (watertight packing paper) were studied. Conclusions: Initial cleaning, reasonable gas drying and hot air drying, and drying in an oven at 35 and $45^{\circ}C$ after cutting the roots resulted in the lowest loss rates in S. Baicalensis root. Hunter color valuse indicated that stroage of dry roots at room temperature was better than PP packaging, and that cold stroage was better than PE packaging for long-term stability.

• The Plant Pathology Journal
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• v.22 no.3
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• pp.203-210
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• 2006

Fumonisins are a group of mycotoxins produced by a pathogen Fusarium verticillioides in infected maize kernels. Consumption of fumonisin-contaminated maize has been implicated in a number of animal and human illnesses, including esophageal cancer and neural tube defects. Since the initial discovery, chemistry, toxicology, and biology of fumonisins as well as the maize-Fusarium pathosystem have been extensively studied. Furthermore, in the past decade, significant progress has been made in terms of understanding the molecular biology of toxin biosynthetic genes. However, there is a critical gap in our understanding of the regulatory mechanisms involved in fumonisin biosynthesis. Here, we review and discuss our current knowledge about the molecular mechanisms by which fumonisin biosynthesis is regulated in F. verticillioides. In addition, we discuss the impact of maize kernel environment, particularly sugar and lipid molecules, on fumonisin biosynthesis.