• 한국세라믹학회지
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• 제43권4호
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• pp.235-241
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• 2006

Mullite short fibers have been fabricated by adapting the Kneading-Drying-Calcination (KDC) process and characterized. The effect of the addition of foaming agent and calcination temperature on the formation of mullite fibers from coal fly ash, was examined. In the present work, ammonium alum $NH_4Al(SO_4)_2\;12H_2O$ synthesized trom coal fly ash and sodium phosphate $Na_2HPO_4\;2H_2O$ were used as foaming agents. After calcination at $1300^{\circ}C$ for 10 h and then etching with 20% HF solution at $50^{\circ}C$ for 5 h using a microwave heating source, the alumina-deficient $(AI_2O_3/SiO_2$ = 1.13, molar ratio) orthorhombic mullite fibers with a width of ${\sim}0.8mm$ (aspect ratio >30), were prepared from the coal fly ash with $AI_2O_3/SiO_2$ = 0.32, molar ratio by the addition of $NH_4AI(SO_4)_2\;12H_2O$, and with further addition of 2 wt% sodium phosphate. The excessive addition of sodium phosphate rather decreased the formation of mullite fibers, possibly due to the large amount of liquid phase prior to mullitization reaction.

• 자원환경지질
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• 제38권6호
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• pp.657-662
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• 2005

Extractions fro fertilizer and soil samples were performed to yield the operationally defined fractions 'soluble' chromate (extractable with $NH_4NO_3$), 'exchangeable' chromate (extractable with phosphate buffer pH 7.2), and these results were compared with the data obtained by extractions with ammonium sulfate, borate buffer pH 7.2, saturated borax pH 9.6, and polyphosphate (Graham's salt). In order to maintain the pH of extractant solution about constant, the concentration of extractant buffer had to be raised to at least 0.5 M. The results strongly depended on the kind of extractant, and the solid: liquid ratio. For most of the samples investigated, the extraction efficiency increased in the order borate-sulfate-nitrate-phosphate. Whereas the recovery of $K_2CrO_4\;and\;CaCrO_4$ added to the samples of basic slags prior to the extraction was about complete, the recovery of added $PbCrO_4$ was highly variable. In soil extracts, the color reaction was interfered from co-extracted humics, which react with the chromate in weak acid solution during the time period necessary for color reaction (1 hour). However, this problem can be overcome by standard addition and subtraction of the color of the extractant solution. In soil extract of about pH < 7, organic material reduced chromate during the extraction period also, and standard addition of soluble chromate is recommended to prove recovery and the stability of chromate in the samples. In admixtures of soils and basic slags, results for hexavalent chromium were lower than from the mere basic slags. This effect was more pronounced in phosphate than in nitrate extracts. As a proficiency test, samples low in organic carbon from contaminated sites in Hungary were tested. The results from $NH_4NO_3$ extracts satisfactorily matched the results of the Hungarian labs obtained from $CalCl_2$ extractants.

• Food Science and Biotechnology
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• 제17권5호
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• pp.1092-1096
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• 2008

Commercial food products from major cities of Coahuila, Mexico were screened to identify residues of transgenic deoxyribonucleic acid (DNA) and/or proteins. After performed, an inventory on all products that contained a soybean-based ingredient in a commercial grocery store in the city of Saltillo, Coahuila, Mexico, 245 food products were identified and grouped in 15 classes according to the soybean ingredient as well as the manufacturing process used for their elaboration. Similar sampling was made for the different food classes in the cities of Monclova, Piedras Negras, and Torreon. A total of 88 samples were analyzed and DNA was extracted by the hexadecyltrimethyl-ammonium bromide (CTAB) technique with slight modification to obtain better DNA quality (1). In addition, segments of the transgenic genes one that codifies for 5-enolpyruvylshikimate-3-phosphate synthase (epsps), cry 1A, and the cauliflower mosaic virus (CaMV) promoter were amplified using polymerase chain reaction (PCR). The transgenic proteins 5-enolpyruvylshikimate-3-phosphate synthase (CP4 EPSPS) and insecticidal crystal protein (Cry 1Ab/Ac) were identified using double antibody sandwich-enzymatic linked immunoassay analysis (DAS-ELISA). Presence of transgenic genes and/or proteins was identified in 35.3% of the commercial products samples.

• 공업화학
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• 제8권5호
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• pp.749-755
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• 1997

몰리브덴산암모늄염과 인산의 반응으로 P/Mo=0.6의 비율을 가진 몰리브덴인산화물을 제조하고 이를 촉매로 사용하여 메틸피라진의 가암모니아 산화반응에 대한 메틸피라진, 산소, 암모니아의 각각의 분압과 반응온도 등의 반응변수의 영향을 살펴보았다. 표준실험조건하의 반응에서 300시간까지의 촉매활성은 안전상태를 유지하였다. 안정화 상태에서의 메틸피라진의 가암모니아 산화반응 속도식은 $-r=kP_{MP}P_{NH3}{^0}P_{O2}{^{\gamma}}({\gamma}=2.2;1.3{\leq}P_{O2}(kPa){\leq}4)$으로 메틸피라진에 대해서는 1차, 암모니아에 대해서는 0차, 산소에 대해서는 분압 4kPa이하에서 2.2차로 나타났다. 623K이하의 반응온도 하에서의 겉보기 활성화에너지는 29.6kcal/mol이었다. 메탈피리진의 주생성물은 시아노피라진으로서 선택도는 전환율에 관계없이 항상 90%이상을 유지하였다.

• 한국식품영양학회지
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• 제10권1호
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• pp.44-52
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• 1997

요석증은 비뇨기과에서 흔히 관찰되는 질환으로서 30∼50대에 많이 발생하고, 남자가 여자보다 발생빈도가 높고, 좌측보다는 우측이 많으며, 문화가 발달한 나라에서는 상부요로 결석이 많으나 후진국에서는 하부요로 결석이 많다. 결석성분은 수산칼슘, 인산칼슘, 인산마그네슘암모늄, 요산, 시스틴 결석과 그들의 혼합결석으로 분류된다. 병태 생리학에 따르면, 결석의 발생원인은 요중의 무기질 농도가 과포화 상태가 되면 결정체핵이 생성된다는 과포화/결정체설, 기질관여설, 억제물질의 결핍설, 에피택시설 등이 있고, 상피소체기능항진중, 과칼슘뇨증, 과요산뇨증, 과수산뇨증, 시스틴뇨증 외에도 원위세뇨관 산증, 과비타민 D증, 소화기계 질환이 통계적으로 유의성 있게 관여된다는 것이다. 본 연구에서는 미란성 위염 환자 K43에서 화학분석법, 적외선 흡수 분석법, image analysis법을 사용하여 재발성 상부요로 결석성분을 분석한 결과 제2 수산칼슘과 인산칼슘의 혼합결석으로 확인되었고, 혈액화학 검사와 요 검사 등 임상검사 성적은 정상치를 유지하고 있었다. 따라서 K43의 재발성 요로결석은 보고된 생성원인이나 인자들에 대한 통계수치와는 연관성이 없었으며 미란성 위염으로부터 영향을 받았다는 증거도 없었다.

• 한국연초학회지
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• 제1권1호
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• pp.1-8
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• 1979

담배 (Va 115) 細胞의 液 培養에서 담배細胞의 多量生産을 할 수 있는 Tank 培養에 關한 基礎調査로 培地造成의 果를 調査하였으며 細胞增殖率에 큰 影響을 미쳤던 2,4-D와 無機燐酸의 果에 關하여 調査하였다. 1. 培地造成에서 細胞增殖率에 많은 影響을 미쳤던 要素는 무糖, 無機燐酸의 濃度,窒素源의 形態 및 植物홀몬,特히 2, 4-D의 有無였다. 2. 무糖의 最適濃度는 3%였으며 3%以上의 濃度에서는 多少 細胞增殖率이 좋은 듯 하였으나 그 差異는 크지 않아 3% 程度로 足하였다. 無機燐酸濃度는 LS 培地內의 無機燐酸의 約 2.5 培인 0.30mg/ml 일 때 細胞增殖率이 가장 좋았다. 3. 液 培地의 窒素源은 암모니아態窒素와 硝酸態窒素가 1 : 2 일 때가 가장 좋았고 窒素源이 암모니아태 만으로 使用하였을 때 細胞增殖率이 가장 낮았으며 硝酸態만 使用되었을 때는 암모니아태만 쓰였을 때 보다는 좋았으나 암모니아태와 硝酸態의 比가 1 : 2 일 때 보다는 떨어졌다. 4. 液 培地에 2,4-D 添加와 無機燐酸濃度를 높이면 細胞增殖率이 增加되는 機作을 調査하기 爲하여 呼吸率과 14C - glucose 吸收利用을 調査하였다. 細胞의 吸收率은 2, 4-D를 添加하면 增加되며 14C-glucose의 吸收는 培地內에 2, 4-D가 包含되거나 (0.2 ppm) 燐酸濃度가 높아지면(對照의 2.5培) 더욱 많았고, 吸收된 14C-glucose는 糖 상태보다 다른 形態,特히 amino 酸이나 有機酸으로 많이 变하였다.

• KSBB Journal
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• 제14권1호
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• pp.36-44
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• 1999

고지혈증 치료제인 Lovastatin을 Aspergillus terreus로부터 생산하기 위해 최적의 탄소원, 질소원, 인산염 및 아미노산을 선정하였다. 단일 탄소원에서는 글리세롤 45mL/L가 Lovastatin 256mg/L로 포도당 45g/L의 기본배지보다 약 3.5배 이상의 높은 Lovastatin 생산량을 나타내었다. 탄소원이 지방산 합성에 이용되는 것을 차단하고 Lovastatin으로의 합성을 촉진하기 위해 기름 증류를 탄소원으로 이용한 결과, 높은 Lovastatin 생산량과 균재량을 나타내었으나, 글리세롤 45mL/L가 Lovastatin 생산량이 낮았다 포도당 50g/L와 글리세롤 50mL/L를 혼합한 복합 탄소원이 Lovastatin 298mg/L로 기본배지에 비해 약 4배 이상의 가장 높은 Lovastatin 생산량을 나타냈었다. 질소원의 영향은 뚜렷하여 질소원에 따라 Lovastatin 생산량이 큰 차이를 나타내었으며, 그 중에서 peptonized milk가 가장 Lovastatin 생산량이 높았다. 인산염 중에서는 $K_2HPO_4$가 가장 높은 Lovastatin 생산량을 나타내었다. 이상에서 얻어진 최적 배지에 각종 아미노산을 첨가한 결과 L-hisbhine과 L-tryptophan이 가장 효과적이었으며, 최적 농도는 둘다 6g/L였다.

• Journal of the korean society of oceanography
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• 제39권4호
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• pp.222-233
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• 2004

Using nitrogen as the limiting nutrient, the default version of a microplankton-detritus model linked chlorophyll concentration to the autotroph nitrogen. However, phosphorus dynamics were added to simulate the results of a microcosm experiment. Using standard parameter values with a single value of microheterotroph fraction in the microplankton taken from the observed range, the best simulation successfully captured the main features of the time-courses of chlorophyll and particulate organic carbon, nitrogen and phosphorus, with root-mean-square error equivalent to 29% of particulate concentration. A standard version of microbiological model assumes complete internal cycling of nutrient elements; adding a term for ammonium and phosphate excretion by microheterotrophs did not significantly improve predictions. Relaxing the requirement for constant microheterotroph fraction resulted in an autotroph-heterotroph model AH, with dynamics resembling those of a Lotka-Volterra predator-prey system. AH fitted the microcosm data worse than did MP, justifying the suppression of Lotka-Volterra dynamics in MP. The paper concludes with a discussion of possible reasons for the success of the simple bulk dynamics of MP in simulating microplankton behaviour.

• 한국토양비료학회지
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• 제8권3호
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• pp.113-119
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• 1975

Volcanic Ash Soils are widely distributed in Jeju island, and constitute the important upland soils which are either presently being cultivated or are suitable for reclaiming. The characteristics of Volcanic Ash Soils according to data made available by previous studies in Jeju and the outside of the country are as following: The most conspicuous mineralogical property is the presence of amorphous mineral colloids. The colloids have large and highly reactive surface to which the common physical and chemical properties are related. Soils are low in bulk density and higher both in porosity and permeability. Accumulation of humus in the upper part of soil is found in great quantity. Cation exchange capacity is high mainly due to high humus content, but the absorbing intensity of ammonium and potassium is weaker than that of crystalline clays. The phosphate absorption coefficient is extremely high and deficiency of minor element may occur both crops and animals. Soils are densely populated with actinomycetes and anaerobic bacteria. Nitrification and activity of urease are distinctly stronger than that of non-Volcanic Ash Soils.

• Mycobiology
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• 제28권3호
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• pp.119-122
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• 2000

Phytases (myo-inositol hexakisphosphate phosphohydrolase; EC 3.1.3.8) are enzymes which catalyze the hydrolisys of phytate into myo-inositol and inorganic phosphates. Phytases are found in plants and a variety of microorganisms. Aspergillus species were treated with 254 nm of UV irradiation for the screening of phytase overproducing mutant strains. At 15 minute irradiation, the survivals of population were less than 5%, and UV irradiation time was decided at 20 minute for the isolation of mutant strains. Four UV mutant strains in A. oryzae (YUV-47, -169, -341, -511) and six in A. ficuum (FUV-17, -36, -69, -193, -317, -419) were isolated on PSM media containing ammonium phosphate. The specific enzyme activities of A. ficuum mutants are 110 to 140% higher than that of wild type.