• 한국대기환경학회지
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• 제17권2호
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• pp.119-131
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• 2001

A total of 328 ambient PM-10 samples was collected by a PM-10 high volume air sampler during the periods of February 1997 to February 1999 from Kyung Hee University at Suwon Campus. The samples were analyzed for their bulk chemical compositions(Cu, Fe, Pb, Zn, Al, $Na^{+}$, $NH_{4}^{+}$, $K^{+}$, $Ca^{2+]$, $Mg^{2+}$, $Cl^{-}$, $NO_{3}^{-}$, and $SO_{4}^{2-}$ by both an atomic absorption spectrophotometer and an ion chromatograph. The purpose of this study was t develop a receptor methodology for quantitative assessment of PM-10 sources. The data obtained from this study were ex-tensively examined using the target transformation factor analysis(TTFA) and the chemical mass balance (CMB). When TTFA was initially applied seasonal basis. five sources(such as automobile-related, sulfate-related, incine-ration, soil and combustion-related) were identified both during winter and fall. Since the total number and the type of sources were resolved by TTFA for the four seasons, CMB was employed to cross-check the results of TTEA. The total of six source categories identified by TTEA was intensively investigated on the basis of source profiles acquired from various source libraries established both in Korea and abroad. The results of this study showed the applicability of two popular receptor models as a new methdology for quantitative assessment PM-10 sources in Korea. Seasonally segmented data sets with the combined application of TTFA and CMB yielded a physically reasonable source apportionment result and provided a mean to increase the number of potential sources. Furthermore, this study suggested the possibility of the CMB application to ambi-ent data from Korea after identifying potential sources through traditional factor analysis.

• Environmental Engineering Research
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• 제16권2호
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• pp.81-90
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• 2011

Different weight percentages of Ag, Pt, and Au doped nano $TiO_2$ were synthesized using the acetic acid hydrolyzed sol-gel method. The crystallite phase, surface morphology combined with elemental composition and light absorption properties of the doped nano $TiO_2$ were comprehensively examined using X-ray diffraction (XRD), $N_2$ sorption analysis, transmission electron microscopic (TEM), energy dispersive X-ray, and DRS UV-vis analysis. The doping of noble metals stabilized the anatase phase, without conversion to rutile phase. The formation of gold nano particles in Au doped nano $TiO_2$ was confirmed from the XRD patterns for gold. The specific surface area was found to be in the range 50 to 85 $m^2$/g. TEM images confirmed the formation a hexagonal plate like morphology of nano $TiO_2$. The photocatalytic activity of doped nano $TiO_2$ was evaluated using 4-chlorophenol as the model pollutant. Au doped (0.5 wt %) nano $TiO_2$ was found to exhibit higher photocatalytic activity than the other noble metal doped nano $TiO_2$, pure nano $TiO_2$ and commercial $TiO_2$ (Degussa P-25). This enhanced photocatalytic activity was due to the cathodic influence of gold in suppressing the electron-hole recombination during the reaction.

• Journal of Pharmaceutical Investigation
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• 제23권3호
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• pp.139-144
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• 1993

Microencapsulation of acyclovir, an effective antiviral agent which acts as a specific inhibitor of herpes DNA polymerase, by carbopol-gelatin complex coacervation has been carried out to develop an oral controlled release preparation, which could improve the absorption characteristics in GI tract. After dissolving carbopol and gelatin separately in distilled water at $40^{\circ}C$, gelatin solution was mixed with carbopol solution while stirring at the same temperature. The pH of the mixture was lowered gradually by dropwise addition of 10% HCI with continuous stirring, and then, at pH 3.5, positively charged gelatin molecules were attracted to negatively charged carbopol. These coacervation processes were observed by optical microscopy during preparation. Plasma concentrations of acyclovir in rats after an oral administration of microcapsule suspension were assayed by HPLC, and pharmacokinetic parameters were calculated based on the model-independent analyses. Two standard formulations, oral solution and intravenous bolus injection, were used as references to compare the bioavailability. It has been revealed that $C_{max}$, $T_{max}$, and MRT of microcapsule suspension were greater than those of oral solution, which results in about two-fold increases in bioavailability. Therefore, in conclusion, the carbopol-gelatin microcapsule of acyclovir might be evaluated as an effective oral controlled release preparation which could increase the bioavailability of acyclovir.

• Journal of Pharmaceutical Investigation
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• 제35권4호
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• pp.279-285
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• 2005

Ground CS-891 (N-[1-(4-methoxyphenyl)-1-methylethyl]-3-oxo-4-aza-5a-androst-1-ene-$17{\beta}$-carboxamide) of poorly water soluble drug was obtained using a Heiko Seisakusho model TI-100 vibration mill, and samples with different crystallinity were prepared at mixture ratios of 10:0, 7:3, 5:5, 3:7 and 0:10 (intact;ground CS-891). Physicochemical characterizations were obtained using qualitative and quantitative X-ray diffractometry, different scanning calorimetry (DSC), scanning electron microscopy (SEM), Quantasorb surface area analyzer, and controlled atmosphere microbalance. With increase of amorphous CS-891 in mixture ratios, the intensities of X-ray diffraction peaks of crystalline CS-891 were decreased, whereas surface area, water absorption, and exothermic peaks in DSC were increased. The apparent solubility of ground CS-891 was $4.4\;{\mu}g/ml$ and the solubility of intact CS-891 was $3.1\;{\mu}g/ml$ at $37{\pm}1^{\circ}C$. The apparent precipitation rates of CS-891 in a supersaturated solution during the solubility test were increased with an increase of amorphous CS-891, and a crystalline form of CS-891 transformed from amorphous CS-891 after the solubility test was found by X-ray diffraction analysis, DSC and SEM. The dissolution profiles of CS-891 with different crystallinity at $37{\pm}1^{\circ}C$ by the USP paddle method were investigated, and the apparent dissolution rate constant of ground CS-891 was about 5.9-fold higher than that of intact CS-891. A linear relationships between the crystallinity of CS-891 and the apparent dissolution rate constant (r>0.96) were obtained.

• Journal of Nutrition and Health
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• 제28권5호
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• pp.415-425
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• 1995

This study was performed to investigate the effect of dietary protein level on the metabolic changes of Ca and skeletons in postmenopausal women, using ovariecotomized rats as an animal model. The female rats of 200∼250g were fed either 8%(L) or 50%(H) casein diet for 15 weeks(1st experiment). At 15th week, the rats of each diet group were undergone ovariectomy or sham-operation and they were continued to feed the same experimantal diet for 9 more months(2nd experiment). Ca metabolism, kidney function and bone composition were determined at the end of 1st experiment, 3rd and 9th month of 2nd experiment. After 1st experiment, high protein group showed higher urinary Ca and protein excretion, however, there was no difference in GFR and urinary hydroxyproline excretion. The weights, ash and Ca content of femur, scapular and vertebra tended to be higher in high protein groups which tells that high protein promoted skeletal growth. In 2nd experiment, high protein group showed higher urinary Ca and protein excretion and lower Ca absorption and balance. GFR was not affected by dietary protein and ovariectomy but increased with time, as well as kidney weight which shows the continuous development of kidney at this age of 15 month in rats. There were no difference in urinary hydroxyproline, serum ALP, and PTH among experimental groups. The weights of femur, scapular, 4th vertebra increased with time, showing the skeleton continues to grow at this age in rats. However, Ca contents, Ca/wt, Ca/ash were decreased with time and tended to be lower in high protein group especially in femur. In conclusion, prolonged feeding of high protein diet deteriorated Ca metabolism and induced bone loss as time after menopause is extended.

• Journal of Pharmaceutical Investigation
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• 제35권5호
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• pp.369-373
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• 2005

The objectives of the current work is to understand the factors impacting the formulation and performance of a Carbopol mucoadhesive buccal delvery system for a model peptide drug, $[D-Ala{^2},\;D-Leu{^5}]$enkephalin (DADLE, Mw=569.7) with comparable chemical and enzymatic stability. Specifically, in vitro buccal DADLE delivery from the cross-linked poly(acrylic acid) (PAA) hydrogel system was characterized. In addition, the influences of several penetration enhancers on the ex vivo buccal absorption of DADLE were also studied. In this study, the PAA hydrogels generally swell to 100% of their original weight in the phosphate pH 7.4 buffer. The water penetration into the PAA hydrogel occurred based on a zero-order kinetics for the first 60 min and steadily decreased afterwards. From the release study, it can be seen that the initial DADLE release was so rapid and the rate of release of DADLE decreased as the time elapsed. The porcine buccal tissue was found to be permeable to DADLE with a flux value of $0.07%/cm{^2}/hr({\pm}0.01\;SD)$. From the ex vivo diffusion study, it was found that sodium taurodihydrofusidate showed a greater degree of enhancement compared to the phospholipids with an Enhancement Ratio (ER) of 8.7 compared to 2.7 and 1.9 for didecanoylphosphatidylcholine and lysophosphatidylcholine, respectively. The work encompassed within this paper has demonstrated the feasibility of using the PAA hydrogel delivery system with its good mucoadhesive properties for the buccal delivery of peptides.

• Journal of Microbiology and Biotechnology
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• 제26권3호
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• pp.503-510
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• 2016

The accumulation (internal and superficial distribution) of magnesium ions (Mg²⁺) by the green freshwater microalga Chlorella vulgaris (C. vulgaris) was investigated under autotrophic culture in a stirred photobioreactor. The concentrations of the three forms of Mg²⁺ (dissolved, extracellular, and intracellular) were determined with atomic absorption spectroscopy during the course of C. vulgaris growth. The proportions of adsorbed (extracellular) and absorbed (intracellular) Mg²⁺ were quantified. The concentration of the most important pigment in algal cells, chlorophyll a, increased over time in proportion to the increase in the biomass concentration, indicating a constant chlorophyll/biomass ratio during the linear growth phase. The mean-average rate of Mg²⁺ uptake by C. vulgaris grown in a culture medium starting with 16 mg/l of Mg²⁺ concentration was measured. A clear relationship between the biomass concentration and the proportion of the Mg²⁺ removal from the medium was observed. Of the total Mg²⁺ present in the culture medium, 18% was adsorbed on the cell wall and 51% was absorbed by the biomass by the end of the experiment (765 h). Overall, 69% of the initial Mg²⁺ were found to be removed from the medium. This study supported the kinetic model based on a reversible first-order reaction for Mg²⁺ bioaccumulation in C. vulgaris, which was consistent with the experimental data.

• Journal of Astronomy and Space Sciences
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• 제18권3호
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• pp.175-190
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• 2001

적정화 종족합성의 선형화 계획을 통하여 자외선 방출이 강한 타원 은하 NGC 4749의 광도 계급과 분광형에 따른 항성 분포를 알아보았다. 종족합성을 위한 항성군을 만들기 위해 $3160\AA$에서 $10800\AA$까지의 파장영역에서 여러 항성종족에 대한 스펙트럼 자료 (Gunn Sf Stryker 1983)를 사용하였다. NGC 4649의 누적 스펙트럼은 Bertola et al. (1982)의 자료를 이용하였다. 주계열 전향점을 이루는 항성종족에 따른 4개의 모형에 대한 종족합성을 수행한 결과 G8-K0V 관을 전향점 종족으로 하는 모형이 NGC 4649의 누적 스펙트럼과 가장 잘 맞음을 확인하였고, 장파장 영역에서의 홉수선은 초중원소 K 거성에 의해 큰 영향을 받는다는 사실을 확인하였다. 종족합성으로부터 구한 NGC 4649의 질량대 광도비 (M/L~ 20)는 역학적으로 구한 값과 비슷함을 알 수 있었으며, 은하의 중심거리에 대한 항성 종족의 분포 특성이 비슷함을 알 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.79-80
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• 2006

A stoichiometric mixture of evaporating materials for $CdIn_2S_4$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, $CdIn_2S_4$ mixed crystal was deposited on thoroughly etched semi-Insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The temperature dependence of the energy band gap of the $CdIn_2S_4$ obtained from the absorption spectra was well described by the Varshni's relation. $E_g(T)=2.7116 eV-(7.74{\times}10^{-4} eV)T^2/(T+434)$. The crystal field and the spin-orbit splitting energies for the valence band of the $CdIn_2S_4$ have been estimated to be 0.1291 eV and 0.0248 eV, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the ${\Delta}so$ definitely exists in the ${\Gamma}_5$ states of the valence band of the $AgInS_2$/GaAs epilayer. The three photocurrent peaks observed at 10K are ascribed to the $A_1-$, $B_1-$, and C1-exciton peaks for n = 1.

• Advances in Traditional Medicine
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• 제7권1호
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• pp.51-64
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• 2007

Mucus is an aqueous gel complex with a constitution of about 95% water, high molecular weight glycoprotein (mucin), lipid, salts etc. Mucus appears to represent a significant barrier to the absorption of some compounds. Natural mucoadhesive agent was isolated and purified from the aqueous extract of the seeds of prosopis pallida (PP). Formulated tablet with the isolated material by wet granulation method. Some natural edible substances are in consideration for candidates as mucoadhesive agents to claim more effective controlled drug delivery as an alternative to the currently used synthetic mucoadhesive polymers. Subjected the materials obtained from natural source i.e. PP and standard synthetic substance, sodium carboxymethyl cellulose for evaluation of mucoadhesive property by various in vitro and in vivo methods. Through standard dissolution test and a model developed with rabbit, evaluated in vitro controlled release and bioadhesive property of theophylline formulation. Mucoadhesive agent obtained from PP showed good mucoadhesive potential in the demonstrated in vitro and in viνo models. The results suggest that the mucoadhesive agent showed controlled release properties by their application, substantially. In order to assess the gastrointestinal transit time in vivo, a radio opaque X-ray study performed in healthy rabbit testing the same controlled release formulation with and without bioadhesive polymer. Plasma levels of theophylline determined by the HPLC method and those allowed correlations to the in vitro mucoadhesive study results. Better correlation found between the results in different models. PP may acts as a better natural mucoadhesive agent in the extended drug delivery system.