• Journal of the Korean Applied Science and Technology
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• v.36 no.4
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• pp.1235-1242
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• 2019

In this study, prepolymer was synthesized through the reaction of isoporon diisocyanate (IPDI) and dimethylolbutanoic acid (DMBA) based on poly (tetramethylene ether) glycol (PTMG) for the synthesis of water-soluble polyurethane to be used as a leather surface coating applied with ethyl acetate and piperazine. Thereafter, the piperazine was chain-extended with 0.01 M, 0.03 M, 0.05 M, and 0.07 M in the water-dispersed resin, and the tensile strength, elongation, CV (cyclic voltammetry), and solvent resistance analysis were performed. Tensile strength of the prepared sample was measured at 5.422 kg_f/㎟ when the piperazine content was 0.07M, and elongation was measured as 587% when the piperazine was 0.01M. Solvent resistance analysis showed the same solvent resistance regardless of piperazine content, and the redox potential was changed according to piperazine content through CV measurement.

• Journal of the Korean Chemical Society
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• v.26 no.5
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• pp.296-303
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• 1982

The solubilities of 1-phenyl-2-acetamido-3-butanone were measured in $H_2O$ at 20, 30 and 40$^{\circ}$C at pressure from 1 to 4500 kg/$cm^2$. Pressure going up to 4500 kg/$cm^2$, the solubility in $H_2O$decreases consistantly as that of diketopiperazine does. As diketopiperazine is a model compound of peptide bond and 1-phenyl-2-acetamido-3-butanone has only one peptide bond and a pretty large hydrophobic group, the solubility behavior is quite surprising. Volume change and heat capacity change data are reasonable.

• Journal of the Korean Chemical Society
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• v.44 no.1
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• pp.4-9
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• 2000

We investigated the self-association and protonation state of norfloxacin, a member of quinokme antibiotics, using electric absorption and potentiom,etric titration. Both nitrogen at the piperazine ring and carboxylic acid were protonated at a low pH (cationic norfloxacin), and deprotonated at a high pH (anionic norfloxacin). In the intermediate pH range, a neutral species was dominant with the possibility of forming a zwitter ion. We also observed that nortloxacin molecules can be sracked to form a dimer at an intermediate pH, The equilibrium constant of the norfloxacin-DNA complex formation, which was measured by Stem-Volmermethod, increases as the pH of the system is lowered. This observation indicates that it is the cationic nortloxacin that forms a complex with DNA among various norfloxacin species in aqueous solution.

• YAKHAK HOEJI
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• v.34 no.2
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• pp.126-132
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• 1990

To enhance the activity of ibuprofen, amides of ibuprofen, 1-piperazinyl-2-(4-isobutylphenyl)propionamide(Ibu-P.A.) and 1-(4-methylpiperazinyl)-2-(4-isobutylphenyl)propionamide (Ibu-M.P.), were synthesized and the pharmaceutical properties and the pharmacological activities of the amides were studied. The lipid:water partition coefficients and pKa values were examined in vitro, and the antiinflammatory effect, analgesic effects, acute toxicity, and intestinal absorption were studied for the amides and compared with ibuprofen in vivo. The results are summarized as belows; 1) The lipid:water partition coefficients of Ibu-M.P. were higher than those of ibuprofen. 2) The calculated pKa values of ibuprofen and Ibu-M.P. were 5.49 and 8.66, respectively. 3) The antiinflammatory effects of ibuprofen, Ibu-P.A., and Ibu-M.P. were same intensity, but the duration of the effects of Ibu-P.A. and Ibu-M.P. were longer than that of ibuprofen. 4) The analgesic effect of Ibu-M.P. was more potent than those of ibuprofen and Ibu-P.A. in the acetic acid-induced writhing test. 5) The $LD_{50}$ was 495 mg/kg for ibuprofen, 187 mg/kg for Ibu-M.P., and over 1250 mg/kg for Ibu-P.A.. 6) The absorption rate constants(k) and half-life($t_{1/2}$) were 0.74($hr^{-1}$) and 0.94(hr) for ibuprofen, and 0.72 ($hr^{-1}$) and 0.96 (hr) respectively for Ibu-M.P..

• Membrane Journal
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• v.18 no.1
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• pp.94-102
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• 2008

For the treatment of the dye wastewater, a polyamide nano-composite membrane and reverse osmosis (RO) membranes were prepared using interfacial polymerization technique, in which piperazine, meta-phenylene diamine, and trimesoyl chloride were used as monomers, Their permselective properties were characterized with aqueous solutions of PEG 600, $Na_2SO_4$, and NaCl, and their performance was compared with that of Osmonics Co, They were found to be a typical nano-composite membrane and a low pressure RO membrane. Using them, a real dye wastewater supplied from the Kyungin Corporation, one of the domestic dye producer, was treated, studying the separation performances of the membranes, Also, during the wastewater treatment, cleaning in place (CIP) of the membranes was carried out regularly to recover the flux of the membranes. Three different chemical cleaners were employed for the CIP process and their performance were compared in this study.

• Analytical Science and Technology
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• v.6 no.1
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• pp.39-45
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• 1993

We have examined Raman spectra of cis-peptide model complex, diketopiperazine in water and $D_2O$ with 320 nm through 218 nm excitation. Our study examines assignment of the resonance enhanced amide vibrations and characterizes their enhancement mechanism. Three resonance enhaned cis-peptide marker bands were observed in aqueous solution at 1676, 1533 and $806cm^{-1}$, which were assigned to the cis-amide I, II and S band, respectively. The $1533cm^{-1}$ amide II band, which is almost pure C-N stretching, was most dominant in water and shifted to $1520cm^{-1}$ upon N-deuteration. This band will be probably a potential probe band for cis-peptide moieties in proteins. The excitation profile data and an Albrecht A-term fit indicated that the cis-peptide vibrations derive their intensities from the 188 nm cis-peptide ${\pi}-{\pi}^*$ electronic transition. We Propose that the geometry of cis-peptide ${\pi}^*$ excited state is C-N bond displacement relative to that of electronic ground state.

• YAKHAK HOEJI
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• v.55 no.6
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• pp.446-450
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• 2011

As an effort to find a new scaffold for ${\alpha}$-glucosidase inhibition, we have prepared total 11 phenylalkylated piperazine derivatives and tested their ${\alpha}$-glucosidase inhibitory activities. Compounds 8 ($IC_{50}=2.73{\pm}0.075mM$) possessing two 3-methoxyphenethyl group on 1,4-position of piperazine showed comparable potency to acarbose used as reference. But other compounds were inactive to ${\alpha}$-glucosidase. The result indicated that proper substituents on the piperazine can engender ${\alpha}$-glucosidase inhibitory activities on the piperazine derivatives.

• Journal of Hydrogen and New Energy
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• v.29 no.5
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• pp.530-537
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• 2018

The effect of temperature and absorption capacity on heat of reaction, which is one of the characteristic studies of $CO_2$ absorption, were investigated in a differential reaction calorimeter (DRC) by using piperazine (PZ) and 2-methylpiperazine (2-MPZ). For all absorbents, $CO_2$ loading capacity decreased with increasing the temperature, while the heat of reaction increased, it figured out that these had a linear correlation between $CO_2$ loading capacity and/or heat of reaction and the temperature. The heat of reaction of all absorbents increased with increasing $CO_2$ loading capacity, especially 2-MPZ rapidly increased at $70^{\circ}C$. The reason for increase in the heat of reaction was occurred the regeneration of $CO_2$, which is a reverse-reaction, simultaneously with the absorption.

• Journal of the Korean Applied Science and Technology
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• v.38 no.3
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• pp.903-913
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• 2021

Three-type PVC membranes denoted by AEM-1, AEM-2, and AEM-3 with a cross-linked anion-exchange group were prepared by substitution reaction of PVC with triethyldiamine (TEDA), 1,4-dimethylpiperazine (DMP), and 1,4-bis(imidazol-1-ylmethyl)benzene (BIB) in cyclohexanone, respectively. We confirmed the successful preparation of the AEM-1, AEM-2, and AEM-3 via ionic conductivity (S/cm), water uptake (%), contact angle, ion-exchange capacity (m_eq/g), thermal properties, SEM and XPS analysis, respectively. The electrochemical capacitor experiments using PVC membrane with cross-linked anion-exchange group in organic electrolytes were performed. The prepared AEM-1, AEM-2 AEM-3 have a good stability by charge and discharge performance in organic electrolyte. As a result, the AEM-2 and AEM-3 membrane based on PVC prepared by the solvent casting method after substituent reaction is suitable for the use as a separator in organic electrochemical capacitor (supercapacitor).