• 한국염색가공학회지
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• 제6권1호
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• pp.44-48
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• 1994

Cellulose triacetate(CTA) liquid crystal solutions obtained via dissolution of CTA in solvent mixture of triflucroacetic acid and methylene chloride were spun and saponified in various chemicals. Among chemicals, methanol/sodium hydroxide mixture endowed highest tenacity as well as modulus to regenerated cellulosic fiber and the fiber thereof showed Cell I or Cell IV morphology, or mixed morphology of Cell I and IV.

• Bulletin of the Korean Chemical Society
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• 제19권7호
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• pp.766-770
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• 1998

On-line preconcentration by direct precipitation with hydroxide has been developed and applied for the analysis of Cd in Inductively Coupled Plasma Atomic Emission Spectrometry. Cadmium is continuously precipitated with hydroxide and dissolved by nitric acid in on-line mode. Currently, the enrichment factor is more than 90 times for 20.0 mL of sample and could be further increased very easily. For a large sample throughput, 1.0 mL of sample loop is used and the enrichment factor is 4.5 with the sampling speed of 15/hr. The method has been applied to the analysis of NIST reference sample and has yielded good results with the certified value.

• 약학회지
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• 제21권3호
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• pp.135-140
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• 1977

Solubilization of cholesterol, its fatty acid esters and gallstones were undertaken employing nonionic, anionic and cationic surfactants. Cholesterol was effectively solubilized by all of these surfactants. Cationic surfactants were most effective. However, cholesteryl myristate was not solubilized at all. In the dissolution test of gallstones in surfactant solutions, cationic surfactant solutions were exceptionally effective in dissolving gallstones. These results suggest the possible existence of interaction between alkylammonium radical and cholesterol on micellar surface.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.412.1-412.1
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• 2002

Purpose. To prepare PVP-based solid dispersions containing lovastatin (LOS) and solubilizers (sodium lauryl sulfate. Tween80. oleic acid) to enhance dissolution of practically insoluble LOS. Methods. Solid dispersions containing LOS were prepared by dissolving two different organic solvent systems (acetone/ethanol or acetonitrile/ethanol). Results. The stickiness and flowability of solid dispersion powders were dependent on the composition and ratio of the solubilizers. (omitted)

• Archives of Pharmacal Research
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• 제26권12호
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• pp.1002-1008
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• 2003

Ferulic acid (3-methoxy, 4-hydroxy cinnamic acid) is a flavoid component possessing antioxidant property. The compound is currently under development as a new drug candidate for the treatment of the dementia. The objective of this preformulation study was to determine the physicochemical properties of ferulic acid. The n-octanol to water partition coefficients of ferulic acid were 0.375 and 0.489 at the pHs of 3 and 10, respectively. Accelerated stability study for ferulic acid indicated that the t 90 value for the drug was estimated to be 459 days at $25^{\circ}C$. Ferulic acid was also found to be unstable under the relative humidity of more than 76%, probably because of the hygroscopic nature of the drug. In order to study compatibility of ferulic acid with typical excipients, potential change in differential scanning calorimetry spectrum was studied in 1: 1 binary mixtures of ferulic acid and typical pharmaceutical excipients (e.g., Aerosil, Avicel, CMC, Eudragit, lactose, PEG, PVP, starch and talc). Avicel, CMC, PVP and starch were found to be incompatible with ferulic acid, indicating the addition of these excipients may complicate the manufacturing of the formulation for the drug. Particle size distribution of ferulic acid powder was in the size range of 10-190 $\mu$m with the mean particle size of 61 $\mu$m. The flowability of ferulic acid was apparently inadequate, indicating the granulation may be necessary for the processing of the drug to solid dosage forms. Two polymorphic forms were obtained by recrystallization from various solvents used in formulation. New polymorphic form of ferulic acid, Form II, was obtained by recrystallization from 1,4-dioxane. The equilibrium solubility for Form I was approximately twice of that for Form II. The dissolution rate of Form II was higher than that of Form I in the early phase (<6 min). Therefore, these physicochemical information has to be taken in the consideration for the formulation of ferulic acid.

• 한국광물학회지
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• 제27권1호
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• pp.53-62
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• 2014

저 품위 엽납석 광석에 포함된 불순물 Fe를 제거하기 위하여 입도크기, 황산농도, 황산암모늄농도, 과산화수소농도 그리고 온도변화에 따른 제거 효율에 대하여 연구하였다. 저 품위 엽납석 광석에서 자형의 입방체 황철석이 포함된 것을 반사현미경으로 관찰할 수 있었으며, X-선 회절분석결과 주 구성광물은 석영과 딕카이트였다. 실험 결과 Fe 용출율이 최대로 나타나는 입도 -325 mesh에서, 황산농도는 2.0 M에서, 황산암모늄 농도는 10.0 g/l, 과산화수소 농도 3.0 M 그리고 최적의 용출 온도는 $70^{\circ}C$에서였다. 용해 동역학 분석에서, Fe 용해는 황철석 표면에서 일어나며 화학적 반응에 통제되는 것으로 그리고 0.066/R, $[H_2SO_4]^{1.156}$, $[(NH_4)_2SO_4]^{0.745}$, $[H_2O_2]^{0.428}$에 비례하는 것으로 나타났다.

• 마이크로전자및패키징학회지
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• 제15권3호
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• pp.41-46
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• 2008

본 연구는 2.5MHF-xMHCl$(x:0\sim8)$ 혼합 용액에서 $EAGLE^{2000TM}$ LCD 유리의 식각에 관한 것이다. 유리의 용해공정에서 율속단계는 HF를 함유한 식각액과 유리와의 반응이었다. 그 증거로는 유리의 두께는 시간에 따라 직선적으로 감소하였고, 식각속도는 교반정도에 무관하게 일정하였으며, 활성화 에너지가 $35\sim45$ kJ/mol 범위였다는 점이다. 순수한 HF만 사용했을 때 보다 HCl이 첨가되면 식각속도는 증가하였고. 그 속도는 HCl 첨가량에 비례하여 증가하였다. 또한 HCl 첨가시 식각 후의 표면은 식각 전과 유사하였다. 이는 HCl 첨가에 의해 $H_{3}O^{+}$ 이온의 농도가 증가하여 각종 불화물의 용해도를 증가시키고, $H_{3]O^{+]$ 이온의 흡착은 Si-O 결합의 결합력을 감소시키기 때문에 일어난 현상으로 사료된다.

• KSBB Journal
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• 제32권2호
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• pp.108-116
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• 2017

Omeprazole, a benzimidazole derivative, suppresses gastric acid secretion by inhibiting $H^+/K^+$ ATPase in gastric parietals cells, and by reducing $H^+$ concentration. To improve stability of esomeprazole magnesium dihydrate (ESMD), enteric-coated preperation was composed of core tablet, subcoating and enteric coating layer. We were evaluated in vitro dissolution characteristics between test and reference ESMD preparation and stability. We could prepare enteric-coated formulation of ESMD by controlling disintegrating agent and coating ratio which could rapidly dissolved in neutral or alkali medium. The formulation D5 with crospovidone of 1.25% and coating ratio of 16.25% had a similar dissolution behavior compare to reference preparation. Difference factor ($f_1$) and similarity factor ($f_2$) were 0~15 and 50~100 and there was no significant difference in bioequivalence between formulations. The content and dissolution rate of formulation D5 were $96.54{\pm}0.21$ and $78.56{\pm}0.87%$ without change of color in accelerated condition ($40^{\circ}C$, RH 75%, high density polyethylene (HDPE) container) for 6 months. This study concluded that our enteric coated preparation of ESMD could be an useful method to improve stability of unstable drug without direct contact with coating material.

• Archives of Pharmacal Research
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• 제18권4호
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• pp.219-223
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• 1995

Rectal absorption of opeprazole, a proton pump inhibitor, from suppositories was studied in rabbits. The suppositories were prepared by the conventional melting method with two types of bases, water-soluble polyethylene glycol (PEG) 4000 and oil-soluble Witepsol H15 bases, and administered intractally (ir) to rabbits at a dose of 10 mg omeprazole/kg. The plasma omeprazole concentration-time profiles of the two suppositories were compared with those following intravenous 9iv) administration of the same dose. There were no significant differences between the two suppositories in bioabailabilities and peak plasma concentrations $(C_{max})$. Bioavaiabilities and $C_{max}$ of PEG- and Witpsol suppositories were 30.3 and 33.9%, and 7.0 and $5.6\mug/ml$, resepectively. However, PEG suppository showed significantly (p<0.05) shorter time to reach peak plasma concentration $(T_{max})$ mean absorption time (MAT) and mean residence time in the plasma (MRT) than Witepsol suppository. The $T_{max}$ MRT nad MAT were 25.0, 83.0 and 38.5 min for PEG syppository, but were 90.0, 122.5 and 78.0 min for Wiepsol supposiotory, respectively. These differences between thw two suppositories could be explanined by the difference in the in vitro dissolution rates between the suppositories. The dissolution of omeprazole form PEG suppository was reportedly much faster than that from Witepsol suppository. It suggests that plasma profiles of omeprazole, especially $C_{max}$ MAT and MRT, could be controlled by modifying the in vitro dissolution rate of the drug from the suppositories. Above results suggest that rectal suppository is worth developing as an alternative dosage form of omeprazole to the conventional oral preparations which need sophisticated treatments, such as enterix coating, to prevent acid degradation of the drug in the stomach fluid.

• 자원리싸이클링
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• 제12권5호
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• pp.10-15
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• 2003

본 연구에서는 세륨연마재 폐슬러리 건조분말로부터 세륨을 포함한 희토류성분과 알루미늄을 분리하고자 하였다. 출발원료인 세륨연마재 폐슬러리 건조분말의 희토류 중에는 산화세륨이 전체 희토류 성분의 약 40% 정도 함유되어 있는데, 산화세륨은 희토류원소들 중에서 가장 안정된 형태로 이에 대한 분해가 용이하지 않다. 그러므로 황산화반응을 이용하여 산화세륨을 분해하므로써 희토류의 분리ㆍ회수율을 향상시키고자 하였으며, 침출용액으로부터 희토류와 알루미늄을 분리하기 위하여, 희토류 원소들은 황산매질에서 황산나트륨과 반응하여 황산나트륨희토류(ReㆍNa($SO_4$)$_2$)를 형성하면서 침전되는 특성을 이용하였으며 쉽게 희토류와 알루미늄을 분리할 수 있었다.