• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3591-3596
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• 2013

The enantioselective aza-Morita Baylis Hillman reaction of nitroalkene and N-tosylimine catalyzed by thiourea-tertiary amine has been investigated using density functional theory. Enantioselectivity is dominated by the cooperative effect of non-covalent and weak covalent interactions imposed by different units of catalyst. As Lewis base, the tertiary amine unit activates nitroalkene via weak covalent bond. The weak covalent interaction orients the reaction in a major path with smaller variations of this bond. The aromatic ring unit activates N-tosylimine via ${\pi}-{\pi}$ stacking. The non-covalent interaction selects the major path with smaller changes of the efficient packing areas. Thiourea unit donates more compact H-bonded network for species of the major path. The calculated ee value in xylene solution phase (97.6%) is much higher than that in N,N-Dimethylformamide (27.2%). Our conclusion is also supported by NBO analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.619-626
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• 2020

The development of new antifreeze mixtures containing non-amine-type corrosion inhibitors, which considers environmental protection, has become a major issue. In this study, four non-amine-type corrosion inhibitors were synthesized and used to produce five kinds of new antifreeze for automobiles to evaluate the rate of copper corrosion. The effects were evaluated by the weight change, surface observation, roughness measurement, and measurement of copper elution in the solution. The amount of copper eluted measured by ICP from Sample 4 was small, and the elution rate was prolonged. Sample 4 showed the best anti-corrosion performance owing to a corrosion suppression effect by passivating copper because the metal surface was smooth after the test, and the corrosion product layer was formed evenly on the surface as small local corrosion was observed. The major corrosion inhibitor added to Sample 4 was 1-aminomethyl(N',N'-di(2-hydroxyethyl)benzotrazole, which contained a certain amount in Sample 5 to show relatively high local corrosion but passivation in progress. Therefore, among the four corrosion inhibitors, 1-aminomethyl(N',N'-di(2-hydroxyethyl)benzotrazole had the highest corrosion inhibitory effect. This corrosion inhibitor prevents corrosion by promoting the passivation of copper on the antifreeze.

• Journal of the Korean Home Economics Association
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• v.25 no.1
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• pp.35-42
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• 1987

Since the 1930's, a rapid development of resin processing has contributed to making our clothing life convenient and rich. Wrinkle considered as the largest defect of cellulose fiber is generated from fixation of molecules which are divided by compression or crookedness. It can be protected by building a bridge between the molecules the joint combination of the inside of the fiber. The formaldehyde reactive resin which is used in processing resin is a chemical compound with more than 2 N-methylol or N-alkoxymethylol group and a chemical compound with N-methylol shows the property of W.W and D.P through the very complex bridge-bonding reaction under the OH group of cellulose and acid catalyst. However, if the processing is excessively carried out, resin-processed textile emits the formaldehyde when the bridge bonding agent reacts to amine type under the acid condition or the formaldehyde remains in the condition of non-reaction or the resin combinates by itself, or the methylol group of non-reactive resin is hydrolyzed due to the insufficient themomagnetic treatment.

• Polymer(Korea)
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• v.25 no.4
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• pp.503-511
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• 2001

Present silica dispersing agents are based mainly on fatty acid derivatives of Zn, K and mixture of fatty acid and metallic soaps are used to increase activity. The viscosity of silica filled rubber is lowered by Zn-K soap type silica dispersing agent, thus fluidity of hydrocarbon chains and processibility is improved. Silica dispersing agent should not exert an influence on chracteristics of vulcanization. But scorch and curing time is shortened by Zn-K soap type silica dispersing agent. A newly developed silica dispersing agent, which is a nonmetal type agent, reduced the viscosity and hardness of silica compounding rubber, and the highly increased degree of dispersion of silica is caused by interaction of silica and rubber. Also it did not affect the curing characteristics and scorch stability of silica compounding rubber.

• Bulletin of the Korean Chemical Society
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• v.23 no.5
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• pp.749-757
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• 2002

Chiral oxazolidin-2-one is easily prepared from D-mannitol and demonstrated to undergo highly diastereoselective alkylation reactions via lithium imide Z-enolates of its N-acyl derivatives to afford ${\alpha}-branched$ products. Evans syn and non-Evans sy n aldol products were also selectively obtained using this new auxiliary in high diastereomeric purity by simply changing the stoichiometry of TiCl4 and the nature of the amine base. Also, this new auxiliary is employed in diastereoselective Staudinger-type ${\beta}-lactam$ syntheses. Using 2-chloro-1-methylpyridinium iodide as the dehydrating agent, the reaction of auxiliary tethered acetic acid with trans imines gave the desired ${\beta}-lactams$ with cis-selectivity.

• The Research Journal of the Costume Culture
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• v.13 no.2 s.55
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• pp.248-254
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• 2005

In this study, wool fabric specimens were pre-mordanted using Sn, Al, Cu, Cr, and Fe, and subsequently dyed using cochineal, maintaining the pH of the dye bath constant using pH buffer solutions of 4, 5, 6, 7, and 8. In the case of wool fabric specimen, regardless of the type of mordanting agents, peak dye-uptake amount was obtained at the acidic region, pH 4, and above pH 6, the dye-uptake amount decreased remarkably. Differing from the cotton fabric case, the dyed wool fabric specimen exhibited red shade even in the case of non-mordanting, at the region of pH values of 4 and 5. It is presumed that in the acidic dye bath the effect of cationic amine group present in the structure of wool fiber molecules took place. The amount of color difference, among the mordanting agents, due to the increase of pH value, was highest for the Fe mordanting case. It seems, therefore, that the Fe mordanting is affected most by the pH value.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.5
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• pp.583-587
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• 2006

Aqueous solutions of sugar alone or in the presence of lysine were gamma irradiated at 0, 5, 10, 20 and 30 kGy at room temperature. Absorbances at 284 nm as an indicator of intermediate stage of non -enzymatic browning reaction increased with irradiation dose in both the solution of sugar or lysine alone and sugar-lysine mixed solution. Absorbances at 420 nm as indicator of browning increased in the irradiated sugar-lysine mixed solutions although no browning was observed in the irradiated solution of sugar or lysine alone. The degree of browning of the irradiated sugar-lysine mixed solution increased with irradiation dose and was dependent on the type of sugar. For sugar-lysine mixed solution irradiated at 30 kGy, the browning had the following order of intensity: sucrose>fructose>arabinose>xylose>glucose. However, the sugar loss of irradiated sugar lysine mixed solution had a following order of intensity: glucose>fructose>sucrose>xylose>arabinose. The reducing power of the non-reducing sugar, sucrose, was produced by gamma irradiation. The present results indicated that gamma irradiation leads to a non-enzymatic browning reaction (carbonyl-amine reaction) in an aqueous system.

• The Journal of Advanced Prosthodontics
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• v.7 no.6
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• pp.496-505
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• 2015

PURPOSE. To determine the effect of fibronectin (FN)-conjugated, microgrooved titanium (Ti) on osteoblast differentiation and gene expression in human bone marrow-derived mesenchymal stem cells (MSCs). MATERIALS AND METHODS. Photolithography was used to fabricate the microgrooved Ti, and amine functionalization (silanization) was used to immobilize fibronectin on the titanium surfaces. Osteoblast differentiation and osteoblast marker gene expression were analyzed by means of alkaline phosphatase activity assay, extracellular calcium deposition assay, and quantitative real-time PCR. RESULTS. The conjugation of fibronectin on Ti significantly increased osteoblast differentiation in MSCs compared with non-conjugated Ti substrates. On the extracellular calcium deposition assays of MSCs at 21 days, an approximately two-fold increase in calcium concentration was observed on the etched 60-${\mu}m$-wide/10-${\mu}m$-deep microgrooved surface with fibronectin (E60/10FN) compared with the same surface without fibronectin (E60/10), and a more than four-fold increase in calcium concentration was observed on E60/10FN compared with the non-etched control (NE0) and etched control (E0) surfaces. Through a series of analyses to determine the expression of osteoblast marker genes, a significant increase in all the marker genes except type I collagen ${\alpha}1$ mRNA was seen with E60/10FN more than with any of the other groups, as compared with NE0. CONCLUSION. The FN-conjugated, microgrooved Ti substrate can provide an effective surface to promote osteoblast differentiation and osteoblast marker gene expression in MSCs.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.10
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• pp.543-550
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• 2016

Amine-type PP-g-VBC-EDA adsorbent, which possesses anionic exchangeable function, was prepared through photoinduced graft polymerization of vinylbenzyl chloride (VBC) onto polypropylene non-woven fabric and subsequent amination reaction using ethylenediamine (EDA). Adsorption characteristics of anionic nutrients on the PP-g-VBC-EDA adsorbent have been studied by batch adsorption experiments. The equilibrium data well fitted the Langmuir isotherm model, and the maximum monolayer sorption capacity was found to be 59.9 mg/g for $NO_3-N$ and 111.4 mg/g for $PO_4-P$. The adsorption energies were higher than 8 kJ/mol indicating anion-exchange process as the primary adsorption mechanism. The pseudo-second order kinetic model described well the kinetic data and resulted in the activation energy of 9.8-36.7 kJ/mol suggesting that the overall rates of $NO_3-N$ and $PO_4-P$ adsorption are controlled by the chemical process. Thermodynamic parameters such as ${\Delta}G^o$, ${\Delta}H^o$ and ${\Delta}S^o$ indicated that the adsorption nature of PP-g-VBC-EDA for anionic nutrients is spontaneous and exothermic. The PP-g-VBC-EDA could be regenerated by washing with 0.1 N HCl.

• Membrane Journal
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• v.30 no.3
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• pp.158-172
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• 2020

In the aspect of saving energy and water, facilitating the separation membrane for the water treatment has been rising recently as one of the possible solutions. However, microbial biofouling effect is the biggest obstacle that hinders reaching higher permeability over a prolonged period of nanofiltration operation. To solve this problem and fully utilize the filtration membranes with enhanced performance, largely two kinds of solutions are studied and the first and the most commonly mentioned type is the one using the silver nanoparticles. Since silver nanoparticles are important to be well tailored on membrane surface, various methods have been applied and suggested. Using silver nanoparticles however also has the drawbacks or possible toxicity risks, raising the need for other types of utilizing non silver particles to functionalize the membrane, such as copper, graphene or zinc oxides, and amine moieties. Each attempt included in either kind has produced some notable results in killing, preventing, or repelling the bacteria while at the same time, left some unsolved points to be evaluated. In this review, the effects of metal nanoparticles and other materials on the antifouling properties of water treatment membranes are summarized.