• Journal of Life Science
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• 제11권1호
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• pp.7-10
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• 2001

Nonactin is the parent compound of a group of ionophore antibiotics, that known as the macrotetrolides. In previous report, in th course of screening superoxide radical-generating compounds from microbial sources, we first screened Streptomyces viridochromogenes JM-4151 that produces nonactin. It was proved that nonactin is superoxide radical-producing compound. In present study, we examined the optimal culture conditions of nonacin. Th optimal culture conditions for nonactin production were as follows: 1% soluble starch, 1% yeast extract, 0.2% ammonium nitrate, 0.06% magnesium sulfate, 0.2% calcium carbonate, initial pH 7.0 at 28$^{\circ}C$ for 96 h. The highest nonactin production was achieved in the production medium of initial pH7.0 at 28$^{\circ}C$ for 96h. The threshold level of dissolved oxygen was found to be above 33.2% at 28$^{\circ}C$ when 1% soluble starch was used as a carbon source. These results suggest that S. viridochromogenes JM-4151 might be a possible strain for industrial nonactin producer.

• 분석과학
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• 제30권4호
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• pp.182-193
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• 2017

In order to examine the variation characteristics of chemical compositions in relation to the inflow pathways of Asian dust, $PM_{10}$ and $PM_{2.5}$ aerosols were collected at Gosan site of Jeju Island during the Asian dust days between 2010 and 2015, and their chemical compositions were analyzed. The mean mass concentrations of $PM_{10}$ and $PM_{2.5}$ during Asian dust days were $130.0{\pm}90.2$ and $38.2{\pm}24.7{\mu}g/m^3$, respectively. The composition ratios of major secondary pollutants ($nss-SO_4{^{2-}}$, $NH_4{^+}$, $NO_3{^-}$) were high as 53.7 % for $PM_{10-2.5}$ and 90.6 % for $PM_{2.5}$. When the Asian dusts had been transported to the Korean Peninsula via Loess Plateau of central China, the concentrations of $nss-Ca^{2+}$, $NH_4{^+}$, $nss-SO_4{^{2-}}$, and $NO_3{^-}$ increased more noticeably. Whereas in case when the inflow pathways of Asian dust had been through the Bohai bay, the concentrations of the crustal species such as Al, Fe, and Ca were relatively high in coarse particles. The atmospheric aerosols were acidified largely by sulfuric and nitric acids. They were neutralized mainly by calcium carbonate in coarse particle mode passed through Manchuria area, but by ammonia in fine particle mode passed through Loess plateau and Bohai bay. Ammonium salts are assumed to exist as ammonium sulfate and ammonium nitrate in coarse particles, but mostly as ammonium sulfate in fine particles.

• 한국대기환경학회지
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• 제14권1호
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• pp.11-23
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• 1998

The purpose of this study was to survey chemical distribution of inorganic elements and ions in the submicron particles, to characterize qualitatively emitting sources by factor analysis, and finally to reveal existing patterns in terms of chemical compounds by a stepwise multiple regression analysis. Total of 141 samples were collected by a cascade impactor from 1989 to1996. Fifteen chemical species (Al, Ba, Cd, K, Pb, Cu, Fe, Ni, $Cl^-, NO_3^-, SO_4^{2-}, K^+, Mg^{2+}, Ca^{2+}, and Na^+$) were characterized by AAS and IC. The study showed that average seasonal levels of submicron particulate matters $(d_p<0.43 \mum)$ were 18.7 $\mug/m^3$ in spring, 15.5 $\mug/m^3$ in summer, 15.7 $\mug/m^3$ in fall, and 24.5 $\mug/m^3$ in winter, respectively. All of the anion concentrations in the particle were highest in the winter season. By applying a factor analysis, 5 source patterns were qualitatively obtained, such as sulfate related source, nitrate related source, oil burning source, calcium related source, and coal combustion source. Finally, when applying a stepwise multiple regression analysis, the results clearly showed that $Na^+ and Ca^{2+}, K^+ and Ca^{2+}, NO_3^-$ and relative humidity, $Cl^-$ and ambient temperature, $Ca^{2+} and Cl^-, Mg^{2+} and SO_4^{2-}, Na^+ and NO_3^-, and Ca^{2+} and NO_3^-$, respectively, are negatively contributed to each other. As a result of those statistical analysis, we could suggest that some chemical compounds in the submicron particles such as$NaNO_3, MgSO_4, Ca(NO_3)_2, and CaCl_2$ may not exist on the filter as final composing products; however, other compounds may possibly exist in the form of $Mg(NO_3)_2, CaSO_4, Na_2SO_4, K_2SO_4, MgCl_2, NaCl, and KCl$. Thus, it must be necessary to identify differences between the results of above statistical analysis and of the real world by laboratory experiments.

• 한국대기환경학회지
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• 제8권3호
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• pp.191-197
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• 1992

In order to investigate the chemical components of acid precipitation at Kangwha near the Yellow Sea and Seoul in Korea, the precipitation samples were collected by wetonly precipitation sampler from February 1991 to January 1992, and pH, electric conductivity(E. C.) and major water-soluble ionic components were analyzed. Strong negative linear correlations were observed between the rainfall amount and the sum of major ionic components in $\mu eq/\ell$ at two sites. The sum of major ionic components also correlated negatively with rain intensity. The analytical results of precipitation samples at two sites were compared each other. Average values of volume-weighted pH were found to be 5.21 at Kangwha and 5.09 at Seoul. The cationic abundance($\mu eq/\ell$) in rainwater showed the general trend $NH_4^+ > Na^+ > Ca^{2+} > Mg^{2-+} > H^+ > K^+$ at Kangwah and $NH_4^+ > Ca^{2+} > Na^+ > H^+ > Mg^{2+} > K^+$ at Seoul. The anionic abundance showed the general trend $SO_4^{2-} > Cl^- > NO_3^-$ at Kangwha and $SO_4^{2-} > NO_3^- > Cl^-$ at Seoul. The concentrations of seasalt such as $Na^+ and Cl^-$ were higher at Kangwha than Seoul. The concentrations of $nss-SO_4^{2-}, nss-Cl^- and NO_3^-$ which are acid composition were higher at Seoul(96.3 $\mu eq/\ell$) than Kangwha(69.0 $\mu eq/\ell$). The contribution of seasalt to the composition of precipitation were higher at Kangwha(34.1%) than Seoul(15.7%). Ammonia and calcium species in rainwater at Kangwha and Seoul are interpreted to have 91% of neutralizing capacity of the original sulfuric and nitric acids. Provided that the precipitation acidity originates primarily from sulfate and nitrate, sulfate was found to contribute about 73-75% of the free precipitation acidity.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.53.1-53.1
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• 2011

Bioactive glass powders were synthesized by hydrothermal chemical route by the use of ultrasonic energy irradiation. We used sodalime, calcium nitrate tetra hydrate and di ammonium hydrogen phosphate as the precursor material to synthesize $SiO_2$ rich bio-active glass materials. The $SiO_2$ content was varied in the precursor mixture to 60, 52 and 45 mole%. Dense compacts were obtained by microwave sintering at $1,100^{\circ}C$. Mechanical properties were characterized for the fabricated dense bioactive glasses and were found to be comparable with conventional CaO-$SiO_2$-$Na_2O$-$P_2O_5$ bioactive glass. Detailed biocompatibility evaluation of the glass composition was investigated by in-vitro culture of MG-63 cell and mesenchyme stem cell. Cell adhesion behavior was investigated for both of the cell by one cell morphology for 30, 60 and 90 minutes. Cell proliferation behavior was investigated by culturing both of the cells for 1, 3 and 7 days and was found to be excellent. Both SEM and confocal laser scanning microscopy were used for the investigation. Western blot analysis was performed to evaluate the bimolecular level interaction and extent and rate of specific protein expression. The ability to form biological apatite in physiological condition was observed with simulated body fluid (SBF). In-vivo bone formation behavior was investigated after implanting the materials inside rabbit femur for 1 and 3 month. The bone formation behavior was excellent in all the bioglass compositions, specially the composition with 60% $SiO_2$ content showed most promising trend.

• 대한치과보철학회지
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• 제44권5호
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• pp.617-627
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• 2006

Statement of problem: HA has been used as a coating material on Ti implants to improve osteoconductivity. However. it is difficult to form uniform HA coatings on implants with complex surface geometries using a plasma spraying technique. Purpose : To determine if Ti6Al4V sintered porous-surfaced implants coated with HA sol-gel coated and hydrothermal treated would accelerate osseointegration. Materials and Methods : Porous implants which were made by electric discharge were used in this study. Implants were anodized and hydrothermal treatment or HA sol-gel coating was performed. Hydrothermal treatment was conducted by high pressure steam at $300^{\circ}C$ for 2 hours using a autoclave. To make a HA sol, triethyl phosphite and calcium nitrate were diluted and dissolved in anhydrous ethanol and mixed. Then anodized implant were spin-coated with the prepared HA sols and heat treated. Samples were soaked in the Hanks solution with pH 7.4 at $37^{\circ}C$ for 6 weeks. The microstructure of the specimens was observed with a scanning electron microscope (SEM), and the composition of the surface layer was analyzed with an energy dispersive spectroscope (EDS). Results : The scanning electron micrographs of HA sol-gel coated and hydrothermal treated surface did not show any significant change in the size or shape of the pores. After immersion in Hanks' solution the precipitated HA crystals covered macro- and micro-pores The precipitated Ca and P increased in Hanks' solution that surface treatment caused increased activity. Conclusion : This study shows that sol-gel coated HA and hydrothermal treatment significantly enhance the rate of HA formation due to the altered surface chemistry.

• Mycobiology
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• 제30권1호
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• pp.22-26
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• 2002

This study was carried out to investigate the possibility for seeds germination of Gastrodia elata using symbiotic fungi. Since seeds of G. elata are very small and lack an endosperm and other nutrients, their germination is difficult without requirement for external nutrients. Out of twenty six isolates collected from protocorms of G. elata and roots of native orchids inhabited in wild, two strains(H-2 and H-21) were observed to stimulate the seed germination of G. elata. The seed germination of G. elates was excellent on oak tree leaves medium. The optimal conditions for mycelial growth of symbiotic fungi were $25^{\circ}C$ and pH 6.0, respectively. The mycelial growth of H-2 strain was excellent on YMA medium, while H-21 was poor on PDA medium. In case of carbon sources, the mycelial growth of H-2 and H-21 was good on media supplemented with glucose and dextrin, respectively. Calcium nitrate was good for mycelial growth of H-2 strain as a nitrogen sources, whereas urea was effective to H-21 strain.

• 한국세라믹학회지
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• 제24권1호
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• pp.70-76
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• 1987

The effect of C12A7 and OH group on the synthesis of C3A by the sol-gel process using aluminum-sec-butoxide and calcium nitrate was studied. C3A by sol-gel method was compared with C3A obtained by the conventional method with respect to their reactivity of formation and crystal size. The sol-gel process for initial formation of C12A7 and C3A at lower temperature (1100, 1200$^{\circ}C$) was superior, but that for complete crystallization of C3A at higher temperature (1300, 1400$^{\circ}C$) was inferior to oxide mixture process. When heat treated under the atmosphere oxygen-free dried nitrogen eliminate the influence of OH group in C12A7, the reactivity of C3A from sol-gel sample incorporated OH group were poor, whereas that from oxide mixture sample showed remarkable effect. The poor crystallization of C3A at higher temperature is presumed to be due to the fact that incorporated OH group in C12A7 formed at lowr temperature might interrupt the diffusion of CaO to C12A7 to from C3A. The crystal size and the hydration characteristics of both C3A obtained by different processes exhibited almost the same results.

• 대기
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• 제33권3호
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• pp.319-330
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• 2023

As the need for PM type observation increases, Surface Particulate Matter Network (SPARTAN), PM samplers analyzes aerosol samples for PM mass concentration and chemical composition, were recently installed at two sites: Yonsei University at Seoul and Ulsan Institute of Science and Technology (UNIST) at Ulsan. These SPARTAN filter samplers and nephelometers provide the PM_2.5 mass concentration and chemical speciation data with aerosol type information. We introduced the overall information and installation of SPARTAN at the field site in this study. After installation and observation, both Seoul and Ulsan sites showed a similar time series pattern with the daily PM_2.5 mass concentration of SPARTAN and the data of Airkorea. In particular, in the case of high concentrations of fine particles, daily average value of PM_2.5 was relatively well-matched. During the Yonsei University observation period, high concentrations were displayed in the order of sulfate, black carbon (BC), ammonium, and calcium ions on most measurement days. The case in which the concentration of nitrate ions showed significant value was confirmed as the period during which the fine dust alert was issued. From the data analysis, SPARTAN data can be analyzed in conjunction with the existing urban monitoring network, and it is expected to have a synergetic effect in the research field. Additionally, the possibility of being analyzed with optical data such as AERONET is presented. In addition, the method of installing and operating SPARTAN has been described in detail, which is expected to help set the stage for the observation system in the future.

• 콘크리트학회논문집
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• 제29권4호
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• pp.415-424
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• 2017

본 연구의 목적은 플라이애시 및 고로슬래그 미분말로 제조한 알칼리 활성화 결합재 모르타르의 황산염 저항성에 미치는 마그네슘(Magnesium, $Mg^{2+}$) 및 황산(Sulfate, ${SO_4}^{2-}$) 이온의 영향을 확인하는 것이다. 이를 위하여 고로슬래그 미분말 치환율을 30%, 50% 및 100%, $SiO_2$와 $Na_2O$의 몰 비($SiO_2/Na_2O$ molar ratio, Ms)를 1.0, 1.5 및 2.0으로 조정한 시험체를 제작하였다. 그리고 $Mg^{2+}$ 및 ${SO_4}^{2-}$의 영향을 확인하기 위하여 $Mg^{2+}$ 단독(10% $Mg(NO_3)_2$), ${SO_4}^{2-}$ 단독(10% $Na_2SO_4$), $Mg^{2+}$ 및 ${SO_4}^{2-}$ 복합(10% [$MgCl_2+Na_2SO_4$], 10% [$Mg(NO_3)_2+Na_2SO_4$]) 및 $MgSO_4$ 수용액(10%, 5% 및 2.5% $MgSO_4$)의 조건에서 압축강도, 길이변화, 질량변화 및 X선 회절 분석을 실시하였다. 그 결과, $Mg^{2+}$ 및 ${SO_4}^{2-}$가 공존하는 경우에만 황산염 침식에 의한 강도저하 및 팽창 등이 발생하는 것을 확인하였다. 이러한 현상은 $Mg^{2+}$이 규산칼슘 수화물(Calcium Silicate Hydrate, C-S-H)을 분해하여 $Ca^{2+}$이 용출되고, 용출된 $Ca^{2+}$과 ${SO_4}^{2-}$가 결합하여 석고($CaSO_4{\cdot}2H_2O$, Gypsum)를 생성하고, $Mg^{2+}$과 OH가 결합하여 수산화마그네슘(Magnesium hydroxide, $Mg(OH)_2$, Brucite)을 생성하는 것에 기인하는 것을 확인하였다.