• Korean Chemical Engineering Research
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• 제49권3호
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• pp.381-386
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• 2011

염료감응형 태양전지의 광전극용 바인더로 화학적으로 기능기 작용을 가진 식물성 오일인 maleinized acrylated epoxidized soybean oil(MAESO)를 이용하였다. 제조된 광촉매의 특성을 고찰하기 위해 FE-SEM, EDS, XRD, XPS, 그리고 질소 흡착법(BET) 분석을 수행하였다. 식물성 오일 바인더를 이용하여 제조된 $TiO_{2}$ 입자는 P-25 광촉매와 비교하여 볼 때 비표면적과 특정한 크기를 갖는 세공의 수가 증가하였는데 이는 광촉매에 기능기가 증가하였기 때문이다. 기능기가 첨가된 $TiO_{2}$ 입자 표면에서 OH 관능기는 9.9에서 16.62%로 증가하였다.

• Journal of Ecology and Environment
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• 제34권2호
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• pp.175-191
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• 2011

Colonization patterns and community changes in benthic macroinvertebrates in the Cheonggye Stream, a functionally restored stream in downtown Seoul, Korea, were studied from November 2005 to November 2007. Benthic macroinvertebrates were quantitatively sampled 15 times from five sites in the stream section. Taxa richness (59 species in total) increased gradually over the first year, whereas the density revealed seasonal differences with significantly lower values in the winter season and after flood events. The benthic macroinvertebrate fauna may have drifted from the upstream reaches during floods and from the Han River, arrived aerially, or hitchhiked on artificially planted aquatic plants. Oligochaeta, Chironommidae, Psychodidae, and Hydropsychidae were identified as major community structure contributors in the stream. Swimmers and clingers colonized relatively earlier in the upper and middle reaches, whereas burrowers dominated particularly in the lower reaches. Collector-gatherers colonized at a relatively early period throughout the stream reaches, and collector-filterers, such as the net-spinning caddisfly (Cheumatopyche brevilineata), predominated in the upper and middle reaches after a 1-year time period. Cluster analyses and multi-response permutation procedures demonstrated that the Cheonggye Stream shares more similarities with the Jungnang Stream than with the Gapyeong Stream. Detrended correspondence analysis and nonmetric multidimensional scaling demonstrated that physical environmental factors (depth, current velocity, dissolved oxygen, and pH) as well as nutrients (total nitrogen and total phosphorous), water temperature, and conductivity could affect the distribution of benthic macroinvertebrates in the study streams.

• 한국재료학회지
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• 제24권6호
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• pp.285-292
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• 2014

Commercial activated-carbon used as the electrode material of an electric double-layer capacitor (EDLC) was posttreated with various acids and alkalis to increase its capacitance. The carbon samples prepared were then heat-treated in order to control the amount of acidic functional groups formed by the acid treatments. Coin-type EDLC cells with two symmetric carbon electrodes were assembled using the prepared carbon materials and an organic electrolyte. The electrochemical performance of the EDLC was measured by galvanostatic charge-discharge, cyclic voltammetry, and electrochemical impedance spectroscopy. Among the various activated carbons, the carbon electrodes (CSsb800) prepared by the treatments of coconutshell-based carbon activated with NaOH and $H_3BO_5$, and then heat treated at $800^{\circ}C$ under a flow of nitrogen gas, showed relatively good electrochemical performance. Although the specific-surface-area of the carbon-electrode material ($1,096m^2/g$) was less than that of pristine activated-carbon ($1,122m^2/g$), the meso-pore volume increased after the combined chemical and heat treatments. The specific capacitance of the EDLC increased from 59.6 to 74.8 F/g (26%) after those post treatments. The equivalent series resistance of EDLC using CSsb800 as electrode was much lower than that of EDLC using pristine activated carbon. Therefore, CSsb800 exhibited superior electrochemical performance at high scan rates due to its low internal resistance.

• Journal of Microbiology and Biotechnology
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• 제20권1호
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• pp.117-126
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• 2010

A chitinase (CHT) and a protease (PRO) were purified from the culture supernatant of Serratia sp. TKU017, with shrimp shell as the sole carbon/nitrogen source. The molecular masses of CHT and PRO determined by SDS-PAGE were approximately 65 kDa and 53 kDa, respectively. CHT was inhibited by $Mn^{2+}$ and $Cu^{2+}$, and PRO was inhibited by most tested divalent metals and EDTA. The optimum pH, optimum temperature, pH stability, and thermal stability of CHT and PRO were pH 5, $50^{\circ}C$, pH 5-7, and <$50^{\circ}C$, and pH 9, $40^{\circ}C$, pH 5-11, and <$40^{\circ}C$, respectively. PRO retained 95% of its protease activity in the presence of 0.5 mM SDS. The result demonstrates that PRO is an SDS-resistant protease and probably has a rigid structure. The $4^{th}$-day supernatant showed the strongest antioxidant activity (70%, DPPH scavenging ability) and the highest total phenolic content ($196{\pm}6.2\;{\mu}g$ of gallic acid equiv./ml). Significant associations between the antioxidant potency and the total phenolic content, as well as between the antioxidant potency and free amino groups, were found for the supernatant. With this method, we have shown that shrimp shell wastes can be utilized and it is effective in the production of enzymes and antioxidants, facilitating its potential use in industrial applications and functional foods.

• Tuberculosis and Respiratory Diseases
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• 제70권3호
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• pp.224-234
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• 2011

Background: Little data is available regarding hospitalized patients with nursing home-acquired pneumonia (NHAP). This is unfortunate because there is an increasing number of elderly persons who are living in nursing homes in Korea. The aim of this study was to compare clinical characteristics and treatment responses of NHAP with community-acquired pneumonia (CAP). Methods: Patients with pneumonia who were admitted from eight nursing homes or from their own homes were enrolled between May 2007 and April 2009. Their clinical characteristics and treatment responses were reviewed retrospectively, and differences between the two groups were analyzed. Results: Of 110 Patients with pneumonia, 66 (60%) were from nursing homes and their median age was 84. In the NHAP group, functional performance status was significantly poorer, classical symptoms of pneumonia were less severe, and multi-lobe involvement (on chest radiographs) was more frequent than in the CAP group. Patients with NHAP more frequently showed lymphocytopenia, anemia, hypoalbuminemia, hypoxemia, and elevated blood urea nitrogen on admission. The mean CURB-65 score was 2.2 in the NHAP group, higher than 1.7 in the CAP group (p=0.004), and multi-drug resistant pathogens were also highly identified in NHAP group (39% vs. 10%, p=0.036). The mean duration of antibiotic therapy was greater for the NHAP (12.6 days) than for the CAP group (6.6 days) (p<0.001). The mortality rate was 23% in NHAP group, which was significantly higher than 5% in the CAP group (p=0.014). Conclusion: NHAP should be more intensively investigated because of the higher frequency of multi-drug resistant pathogens and mortality than the CAP.

• Carbon letters
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• 제6권1호
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• pp.41-46
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• 2005

Plasma carbon blacks of 20~30 nm diameter were synthesized by direct decomposition of natural gas using a hybrid plasma torch system with 50 kW direct current and 4 MHz of radio frequency. The insulating rector which inside diameter of 400 mm and length of 1500 mm, respectively was kept at 300~$400^{\circ}C$ during the preparation. The ultimate analysis of plasma carbon blacks reveals that the raw plasma carbon blacks contains a large quantity of volatile which is mainly consist of hydrogen. Therefore devolatilization of raw plasma carbon blacks were carried out at $900^{\circ}C$ for one hour under nitrogen atmosphere. The devolatilization leads to the decrease in electrical resistivity and surface oxygen functional groups of plasma carbon black significantly. In order to investigate the plasma carbon as a catalyst support, devolatilized plasma black at $900^{\circ}C$ (DPB) supported PtAu catalyst was synthesized by sodium boronhydride reduction method. Electrochemical measurements and direct formic acid fuel cell test indicated that catalytic activity of DPB supported PtAu catalyst for formic acid oxidation was similar to that of Vulcan XC-72 of commercial carbon black supported one.

• 공업화학
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• 제24권4호
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• pp.402-406
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• 2013

본 연구에서는 납사 크래킹 잔사유로부터 용융전기방사용 핏치가 열처리 개질 방법에 의하여 제조되었다. 개질된 핏치의 연화점과 물성은 질소유량, 열처리 온도 및 반응시간 같은 개질 조건에 따라 영향을 받았다. 이중에서 열처리온도가 핏치의 분자량 분포 및 연화점에 큰 영향력을 미쳤다. 열처리 온도가 증가함에 따라서 표면 작용기들의 분해와 고리화 반응으로 C/H 몰비와 평균분자량이 증가하였다. 또한, 벤젠 불용분(BI)과 퀴놀린 불용분(QI)값이 감소되었고, 분자량 분포의 폭이 더 좁아지는 것으로 보여주었다. 연화점이 $155^{\circ}C$인 개질 핏치로부터 용융전기방사법을 이용하여 $4.8{\mu}m$의 직경을 갖는 탄소섬유를 얻을 수 있었다. 용융전기방사법이 저섬경화 섬유를 제조하는데 기존의 용융방사법보다 더 용이할 것으로 여겨진다.

• 한국작물학회지
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• 제49권4호
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• pp.295-299
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• 2004

The prices of domestic green tea products are relatively expensive and price differences within products of the same levels of quality are various. Also, there is no basic criteria on evaluation of green tea quality. To group 43 commercial green tea products into several parts by the principal component and cluster analyses, this work was done by use of 8 chemical constituents which were analyzed by NIR system. The principal component and cluster analyses revealed 8 groups. The first group included 16 products that had lower free amino acid and theanine contents. The second group included 5 products having higher free amino acid and theanine contents, but lower ash contents. The third group included 13 products showing medium values of 8 constituents. The IV group included 4 products having higher contents of moisture, free amino acids, and theanine. The V group included 1 product showing higher moisture but lower catechins contents. The VI group included 2 products that had higher moisture and catechins contents, but lower free amino acid and theanine contents. The VII group had higher moisture and catechins contents. The VIII group had higher ash and vitamin C contents. The free amino acid contents which were the most important in flavor evaluation of green tea quality did highly positively correlate with the contents of total nitrogen $(0.956^{**}),\;theanine\;(0.981^{**}),\;and\;caffeine\;(0.793^{**})$, but negatively with the contents of ash $(-0.884^{**})$. The catechins used as for functional ingredients did correlate with contents of caffeine(+) and vitamin C(-), respectively.

• 한국응용과학기술학회지
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• 제30권1호
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• pp.1-8
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• 2013

알킬렌디아미노 기능기를 분자 내에 갖는 4종의 새로운 알킬렌디아미노알킬-비스-포스폰산 유도체들을 합성하고, 그들의 연기밀도를 측정하였다. 이 화합물들은 알킬렌디아민 및 알데히드에 인산을 첨가하여 한 단계로 반응시켜 2개의 인산에 2개의 아미노기를 갖는 화합물로서 76~97.3%의 수율을 얻었다. 이들의 연기밀도 시험은 ASTM E 662의 방법으로 측정하였으며, 시험결과 연기밀도(Ds)값이 234.7~437.9으로 측정되었고, 2개의 인산을 갖는 화합물이 1개의 인산구조를 갖는 화합물보다 연기밀도가 증가되었다. 따라서 하나 또는 두 개의 인산에 결합된 아마노기의 질소수와 연기밀도 사이에는 관련이 있었다.

• 한국미생물·생명공학회지
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• 제41권1호
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• pp.60-69
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• 2013

Purified melanin pigment from Klebsiella sp. GSK was characterized by thermogravimetric, differential thermal, X-ray diffraction and elemental analysis. This melanin pigment is structurally amorphous in nature. It is thermally stable up to $300^{\circ}C$ and emits a strong exothermic peak at $700^{\circ}C$. Its carbon, hydrogen and nitrogen composition is 47.9%, 6.9% and 12.0%, respectively. It was used to scavenge metal ions and free radicals. After immobilizing the pigment and using it to adsorb copper and lead ions, the metal ion adsorption capacity was evaluated by atomic absorption spectroscopy (AAS) and the identity of melanin functional groups involved in the binding of metal ions was determined by Fourier transform infrared (FT-IR) spectroscopy. Batch adsorption studies showed that 169 mg/g of copper and 280 mg/g of lead were adsorbed onto melanin-alginate beads. The metal ion adsorption capacity of the melanin-alginate beads was relatively significant compared to alginate beads. The metal ion desorption capacity of HCl was greater (81.5% and 99% for copper and lead, respectively) than that of EDTA (80% and 71% for copper and lead, respectively). The ability of the melanin pigment to scavenge free radicals was evaluated by inhibition of the oxidation of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and was shown to be about 74% and 98%, respectively, compared with standard antioxidants.