• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.34 no.1
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• pp.1-6
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• 2002

Alkaline sizing characteristics of TMP (thermomechanical pulp) handsheets with AKD (alkylketene dimer) were studied under various conditions. The sizing degree of TMP handsheet was much lower than that of chemical pulp. Especially, the sized TMP handsheet dried at $20^{\circ}C$ showed no sizing features, but sizing degree of TMP handsheet was clearly Increased by heat treatment at $105^{\circ}C$. The sizing effect of TMP was also improved by addition of $CaCO_3$, but it was not affected by pH. Therefore, sizing effect of TMP with AKD can be improved to some extent by controlling stock condition and heat treatment of handsheet.

• Journal of the Korean Graphic Arts Communication Society
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• v.14 no.1
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• pp.17-29
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• 1996

N-substituted acrylamide hydrogel is reported to have the feature of bing transparent and sensitive enough to response to a temperature stimulus below the temperature of phase transition. Especially at the near of 35 C it becomes shrunk and opaque very quickly. It has also the characteristic of reversing swelling and shrinking. The experiment showed that it is possible to produce a functional gel of super water absorption with the process of free radical polymerizing PVA(polyvinylalcohol) and PAA(polyacrylamide), and crosslinking. The ratio of shrinking and swelling caused by copolymerization rises 10% to 80% at the each temperature of 20 C, 30 C, 40 C, respectively. Phase transition temperature of this gel by copolymerization is50 C while that of ordinary N-substituted acrylamides is between 32~35 C. This temperature reaches the rearing limit of animals and plants so that volumetric transition polymer gel can be ulilized in varying fields such as agriculture/gardening which are water-using field, on-off switch sensing temperature and volumetric variation, processing of liquid wastes and civil engineering works, architecture and electronics. We have no doubt that this material will be the high-functional resin in the hi-tech age of the near future.

• Bulletin of the Korean Chemical Society
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• v.16 no.4
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• pp.321-325
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• 1995

Adsorption mechanisms of diisobutyl dithiophosphinate (DIBDTPI) and diisobutyl monothiophosphinate (DIBMTPI) on gold and gold-silver alloys (80:20 and 50:50) have been studied. The adsorption mechanisms on gold-silver alloys can be explained by the EC mechanism involving an electron transfer step and a chemical reaction step. Thus, the adsorption should be controlled by the E of the electrochemical oxidation of the electrode involved and the pK of the metal collector complex. Both di- and mono- thiophosphinate adsorb on 50:50 Au-Ag alloy at lower potential than on 80:20 Au-Ag alloy surface. There are no significant differences between the reactivities of DIBDTPI and DIBMTPI with precious metals except that the dithio- compound can be oxidized to dimer on gold at high potentials, while the monothio- homologue cannot. In this regard, DIBDTPI may be a better surface active reagent for pure gold than DIBMTPI.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.11b
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• pp.50-55
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• 1999

Sizing development of AKD-sized paper by beta-ketoester formation has been debated until recent years because of absence of its obvious and direct spectroscopic evidence. In this study, reaction between AKD and cellulose was investigated to disclose the possibility of beta-ketoester formation between two components under no catalyzed neutral condition. In absence of water, AKD reacted with cellulose to form beta-ketoester linkage under no catalyzed neutral condition, while, in presence of water, most of AKD was hydrolyzed to a dialkyl ketone or beta-ketoacid. Therefore, the main mechanism of AKD sizing would not be the formation of beta-ketoester between AKD and cellulose in the papermaking process. It could be suggested that the sizing development of AKD-sized paper is obtained by next two mechanisms: 1) formation of a thin-layer of AKD on the fiber surface through melting and spreading of AKD emulsion particles by heat, and 2) the formation of ketone by the hydrolysis of AKD during drying and storage of AKD-sized papers.

• The Korean Journal of Physiology and Pharmacology
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• v.15 no.3
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• pp.123-128
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• 2011

Caesalpinia sappan (C. sappan) is a medicinal plant used for promoting blood circulation and removing stasis. During a screening procedure on medicinal plants, the ethylacetate extract of the lignum of C. sappan (CLE) showed inhibitory activity on arginase which has recently been reported as a novel therapeutic target for the treatment of cardiovascular diseases such as atherosclerosis. CLE inhibited arginase II activity prepared from kidney lysate in a dose-dependent manner. In HUVECs, inhibition of arginase activity by CLE reciprocally increased NOx production through enhancement of eNOS dimer stability without any significant changes in the protein levels of eNOS and arginase II expression. Furthermore, CLE-dependent arginase inhibition resulted in increase of NO generation and decrease of superoxide production on endothelium of isolated mice aorta. These results indicate that CLE augments NO production on endothelium through inhibition of arginase activity, and may imply their usefulness for the treatment of cardiovascular diseases associated with endothelial dysfunction.

• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2663-2670
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• 2013

The purpose of stability testing is to provide evidence about how the quality of a drug varies with time under the influence of a variety of environmental factors. In this study, erythropoietin (EPO) was analyzed under different pH (pH 3 and pH 9) and temperature ($25^{\circ}C$ and $40^{\circ}C$) conditions according to current Good Manufacturing Practice (cGMP) and International Conference on Harmonisation (ICH) guidelines. The molecular weight difference between intact EPO and deglycosylated EPO was determined by SDS-PAGE, and aggregated forms of EPO under thermal stress and high-pH conditions were investigated by size exclusion chromatography. High pH and high temperature induced increases in dimer and high molecular weight aggregate forms of EPO. UPLC-ESI-TOF-MS was applied to analyze the changed modification sites on EPO. Further, normal-phase high-performance liquid chromatography was performed to identify proposed glycan structures and high pH anion exchange chromatography was carried out to investigate any change in carbohydrate composition. The results demonstrated that there were no changes in modification sites or the glycan structure under severe conditions; however, the number of dimers and aggregates increased at $40^{\circ}C$ and pH 9, respectively.

• BMB Reports
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• v.28 no.5
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• pp.408-413
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• 1995

Decrease in the amount of cotyledonary spermidine in Glycine max under anaerobic conditions related to an increase in spermidine dehydrogenase. Under the same conditions, no enzymatic activity of diamine oxidase was observed. Exposure of Glycine max both to spermidine and 1,3-diaminopropane under anaerobic conditions resulted in a decrease in spermidine contents. Correlated with the decrease in spermidine contents, there was a drastic increase in spermidine dehydrogenase. The molecular weight of the purified enzyme estimated by Sephacryl S-300 gel column and SDS gel electrophoresis were 130,000 dalton and 65,000 dalton, respectively, indicating that the enzyme is a dimer. The optimal pH for activity was 9.3. The $K_m$ value for spermidine was 0.61 mM. Neither metal ions nor polyamine and derivatives affected enzymatic activity, but the enzyme was inhibited by DTNB, NEM and PCMB, suggesting that a cysteine residue of the enzyme is associated with or involved in enzyme activity. To our knowledge, this is the first report describing properties of the enzyme from plants. Considered together, the data in this paper indicate that both spermidine and 1,3-diaminopropane, novel activators, enhance the spermidine dehydrogenase activity and control the intracellular spermidine contents.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.229-232
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• 2005

The study on the improvement of manufacturing process of RJ-4 liquid fuel that have high flash point, was carried out. In preparing of RJ-4 using commercially available MCPD, 1st, 2nd hydrogenation and isomerization reaction were enabled 1 step continuous process by combined use of heteropoly phosphoroustungstic cesium salt catalyst and 2nd stage-heat-controllable reactor. Also when heteropolyacid cesium salt was used as a isomerization catalyst instead of aluminum chloride, formation rate of exe-THDMCPD was higher, the catalyst could be easily separable from product and there was no production of waste acid, so this new reaction condition was confirmed as the environment friendly process.

• Journal of Microbiology and Biotechnology
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• v.28 no.11
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• pp.1806-1813
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• 2018

A new sesquiterpene lactone dimer [1], together with five known compounds (2-6), was isolated from the flowers of Inula britannica. The structures of these compounds were established by extensive spectroscopic studies and chemical evidence. The inhibitory activities of these isolated compounds (1-6) against human neutrophil elastase (HNE) were also evaluated in vitro; compounds 1 and 6 exhibited significant inhibitory effects against HNE activity, with $IC_{50}$ values of 8.2 and $10.4{\mu}m$, respectively, comparable to that of epigallocatechin gallate (EGCG; $IC_{50}=10.9{\mu}M$). In addition, compounds 3 and 5 exhibited moderate HNE inhibitory effects, with $IC_{50}$ values of 21.9 and $42.5{\mu}M$, respectively. In contrast, compounds 2 and 4 exhibited no such activity ($IC_{50}$ > $100{\mu}M$). The mechanism by which 1 and 3 inhibited HNE was noncompetitive inhibition, with inhibition constant ($K_i$) values of 8.0 and $22.8{\mu}M$, respectively.

• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.783-792
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• 2014

The binding interaction between a hemolytic peptide ${\delta}$-lysin and a zwitterionic lipid bilayer POPC was investigated through a series of molecular dynamics (MD) simulations. ${\delta}$-Lysin is a 26-residue, amphipathic, ${\alpha}$-helical peptide toxin secreted by Staphylococcus aureus. Unlike typical antimicrobial peptides, ${\delta}$-lysin has no net charge and it is often found in aggregated forms in solution even at low concentration. Our study showed that only the monomer, not dimer, inserts into the bilayer interior. The monomer is preferentially attracted toward the membrane with its hydrophilic side facing the bilayer surface. However, peptide insertion requires the opposite orientation where the hydrophobic side of peptide points toward the membrane interior. Such orientation allows the charged residues, Lys and Asp, to have stable salt bridges with the lipid head-group while the hydrophobic residues are buried deeper in the hydrophobic lipid interior. Our simulations suggest that breaking these salt bridges is the key step for the monomer to be fully inserted into the center of lipid bilayer and, possibly, to translocate across the membrane.