• 약학회지
• /
• 제13권2_3호
• /
• pp.80-83
• /
• 1969

Acetylsalicylic acid gives a water-insoluble violet complex with $<\alpha>$-Picolin-Cu(II) reagent. The Complex is extractable well with a mixture of $<\alpha>$-Picolin-tetrachloromethane solution. The Complex salt dissolved in the mixed solution shows a maximum absorption at 620 m$<\mu>$. It has a melting point at $171^{\circ}C-$173^{\circ}C and molar ratio of Acetylsalicylic acid: Cu(II): $<\alpha>$-Picolin was estimated as 2:1:2 by continuous variation method and chelate titration method.

• Restorative Dentistry and Endodontics
• /
• 제21권1호
• /
• pp.161-173
• /
• 1996

The cariostatic effect of fluoride had been established by many epidemiologic and experimental studies. But, there are still different views on the mechnism of cariostasis and remineralization, especially about the proper fluoride concentration. The purpose of this study is to ascertain the remineralization of caries lesion and influence of fluoride concentration which affect remineralization by a study based on dynamic mechanism. The subjects, sound permanent teeth without demineralization or crack, were immersed in lactic acid buffered demineralization solution for 4 days. Dental caries with surface zone and subsurface lesion were artificially produced. All specimens were immersed in lactic acid buffered remineralization solution which had fluoride concentrations of 1 ppm, 2 ppm, 3 ppm for 10days. Final conclusions were obtained by observing the specimens for every 10 days under polarized microscopy. 1. Remineralization of caries lesion as well as demineralization of enamel were produced by changing the degree of saturation of lactic acid buffer solution. 2. Remineralization of caries lesion was facillitated by fluoride ion in lactic acid buffer solution. but, remineralization of the entire caries lesion was not increased as fluoride ion concentration increased.

• 한국응용과학기술학회지
• /
• 제30권3호
• /
• pp.504-517
• /
• 2013

The purpose of this study was to process extraction and separation for polyglucose porpyran from pophyra yezoensis as high yield. The acidic porphyran solution was extracted with 0.1~1N of ${\alpha},{\beta}$-dichloromaleic acid or ${\alpha}$-chloromaleic acid of 2% solution as organic acid instead of inorganic acid at $60^{\circ}C$ and then porphyran was collection of high yield to acidic solution and it was neutralization treated with 0.1N of $d-Ca(OH)_2$ solution and the mixture was conversion to porphyran salt form and treated with a shell powder of ouster and then added of ethanol as precipitator. It recovery porphyran contained of violet purple laver coloring matter was obtained as a crystalline and used for the next step without future purification to prepare of porphyran laver jam. so, The resulting porphyran and porphyran jam was characterized by it component and physical properties.

• 폴리머
• /
• 제27권2호
• /
• pp.159-166
• /
• 2003

폴리(비닐 알코올) 하이드로젤 입자의 표면에 음이온성을 부여하기 위하여 비닐아세테이트(VAc)와 메타아크릴산(MMA)을 현탁 공중합하였다. $^1$H-NMR을 통해서 공중합된 입자의 표면에 카르복실기가 도입되었음을 확인하였다. poly(VAc-co-MAA) 입자를 알칼리 용액에서 불균일계 비누화를 하였으며, 단독 PVAc 입자 보다 비누화 반응이 빠름을 관찰하였다. 또한 이들 입자를 산성 용액과 알칼리 용액에서 연속적으로 처리하여 입자들의 팽창 정도를 관찰하였다. 비누화된 입자들은 산성 수용액에서는 수축이 되었다가 알칼리 수용액에서는 팽창하는 가역적인 성질을 보였다. 비누화된 입자들은 다량의 수분을 흡수하는 하이드로젤 형태였으며, $^1$H-NMR, FT-IR을 통해서 하이드로젤 표면에 -COOH기가 형성된 것을 확인할 수 있었다.

• 한국환경과학회지
• /
• 제21권9호
• /
• pp.1031-1041
• /
• 2012

This study was carried out to investigate the characteristics of disinfection by-products (DBPs-trihalomethanes (THMs), haloacetic acids (HAAs) and haloacetonitriles (HANs) formation in chlorination of principal raw waters used for drinking water on Jeju Island, Korea. The domestic water supply of other area and humic acid solution (HA) were used as a reference point. The effects of chlorine contact time, solution temperature and pH on DBPs formation potential (DBPFP) were investigated for raw waters. In addition, the effect of $Br^-$ was studied for HA. The DBPFP (THMFP, HAAFP and HANFP) were increased with increasing chlorine contact time. Comparing the individual DBPFPs for raw waters, they decreased in the order of HAAFP > THMFP ${\geq}$ HANFP. As the solution temperature was increased, the THMFP, HAAFP and HANFP increased. With increasing the solution pH, the THMFP was increased, but HAAFP and HANFP were decreased. With the addition of 0.3 mg/L $Br^-$ for HA, the DBPFP was increased and the major chemical species changed: from trichloromethane to dibromochloromethane and tribromomethane for THMs; from dichloroacetic acid and trichloroacetic acid to tribromoacetic acid for HAAs; and from dichloroacetonitrile to dibromoacetonitrile for HANs.

• 한국재료학회지
• /
• 제16권1호
• /
• pp.63-67
• /
• 2006

The characteristics of the wet-etching of ZnO thin films were investigated using hydrochloric and phosphoric acid solutions as etchants. The etch rate of ZnO films, using highly diluted hydrochloric acid solutions at a concentration of 0.25% in deionized water, was determined to be about 120 nm/min, and linearly increased with increasing the acid concentration, resulting in $1.17{\mu}m/min$ when a 2% HCl solution was used. The surface of ZnO etched by an HCl solution, observed by scanning electron microscopy, showed a rough morphology with a high density of hexagonal pyramids or cones with sidewall angles of about ${\sim}45^{\circ}C$. Moreover, the sidewall angles of the masked area were similar to those of the pyramids on the surface. In comparison, the surface of ZnO etched by a phosphoric acid had a smooth surface morphology. The origin of this difference is from the very initial stage of etching, indicating that the etch-mechanism is different for each solution. Furthermore, when $H_3PO_4$ was added to the HCl aqueous solution, the morphology of the etched surface was greatly enhanced and the sidewall angle was also increased to about $65^{\circ}C$.

• 공업화학
• /
• 제10권2호
• /
• pp.287-292
• /
• 1999

Polycarbonate (PC)를 matrix로 사용하여 전도성 고분자인 polyaniline (PANI)과의 복합체를 블렌딩 방법에 의하여 제조하였다. 용매로는 chloroform을 사용하였으며 PANI는 전하수송을 가능하게 하고 유기용매에 잘 용해될 수 있도록 camphorsulfonic acid (CSA) 혹은 dodecylbenzenesulfonic acid (DBSA)와 같은 알킬 벤젠 술폰산으로 양성화시켰다. 또한, 전도성 복합체의 전기전도성은 압축성형이 아닌 solution casting법에 의하여 향상시켰다. 아울러 양성화제 유무, PANI의 함량 또는 온도에 따라 전기전도도, 몰포로지 및 인장강도 등을 측정 분석하였다. PANI 착체의 함량이 많을수록 전기전도도는 증가하였으며 알킬사슬이 긴 DBSA로 양성화된 25 wt % PANI 착체의 전도성 복합체의 전기전도도는 3.18 S/cm까지 향상되었다.

• 대한화학회지
• /
• 제10권3호
• /
• pp.119-128
• /
• 1966

The glass electrode was empirically calibrated in methanol-and 2-propanol-water mixed solvents, by means of which the pH-meter reading could be converted to stoichiometric hydrogen ion concentration. The thermodynamic dissociation constants of hydrogen cupferrate in methanol-and 2-propanol-water solution were potentiometrically determined with the changes in composition of organic solvents at 0.01 and 0.05 of the ionic strength and 25$^{\circ}C$. The empirical formula of the constants with mole fraction (n) of the organic solvent are as follow: methanol-water solution $pK_a$= 2.24n + 4.29 at ${\mu}$ = 0.01 n = 0.0476∼0.642 $pK_a$ = 2.35n + 4.38 at ${\mu}$ = 0.05 n= 0.0446~0.642 2-propanol-water solution $pK_a$= 5.50n + 4.48 at ${\mu}$ = 0.05 n = 0.0253~0.259 The relationships between $pK_a$ of acetic acid, propionic acid and HCup and dielectric constant of some mixed solvents were discussed. It would be considered that the factors effecting $pK_a$ value of weak acid in mixed-solvent are not only dielectric constants but acid-base character and solvation effect of the solvent, etc.

• 대한화학회지
• /
• 제6권1호
• /
• pp.32-35
• /
• 1962

Six frogs (Rana nigromaculata 25∼40 gm) were adapted to light for 2 hours. Then 0.02 ml of 3% nicotinamide and 0.02 ml of 0.6% folic acid were injected into the vitreous body of the right eye-ball, and 0.02 ml normal saline solution into the vitreous body of the left eye-ball respectively. After dark adaptation for an hour-their heads were cut off under a dim red light (650 $m{\mu}$). The retinae were removed from the left eye-ball for the control group and from the right for the test group respectively. Then rhodopsin was extracted from the retinae with 3 ml of 2% digitonin solution(pH = 7.0) for 17 hours at 0$^{\circ}C$ in the dark. The optical densities before and after the illumination of the extract were measured and compared with those of the control group. The results are as follows: 1) The group which had been injected with 0.02 ml of 3% nicotinamide solution had the promotive action on tile regeneration of rhodopsin in comparison with the control group. 2) The group which had been injected with 0.02 ml of 0.6% folic acid solution had the controlling action on the regeneration of rhodopsin in comparison with the control group.

• 대한금속재료학회지
• /
• 제47권9호
• /
• pp.558-566
• /
• 2009

The alloying effect of a small amount of nickel on low alloy steel for application to flue gas desulfurization(FGD) systems was studied. The structural characteristics of the rust layer were investigated by scanning electron microscopy(SEM). The electrochemical properties were examined by means of potentiostatic polarization test, potentiodynamic polarization test, and electrochemical impedance spectroscopy(EIS) in a modified green death solution of 16.9 vol.% $H_2SO_4$+0.35 vol.% HCl at $60^{\circ}C$ and an acid rain solution of $6.25{\times}10^{-5}M\;H_2SO_4+5.5{\times}10^{-3}M\;NaCl$ at room temperature. It was found that as the amount of nickel increased, the corrosion rate increased in the modified green death solution, which seemed to result from micro-galvanic corrosion between NiS and alloy matrix. In acid rain solution, the corrosion rate decreased as the amount of nickel increased due to the repulsive force of $NiFe_2O_4$ rust against $Cl^-$ ions by electronegativity.