• 한국자기공명학회논문지
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• 제1권2호
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• pp.126-140
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• 1997

Mesoporous MCM-41 gallosilicate material was synthesized through shifting through shifting gallosilicate polymer equilibrium towards a MCM-41 phase by addition of acid. The location of Cu(II) exchanged into MCM-41 and its interaction with various adsorbate molecules were investigated by electron spin responance and electron spin echo modulation spectroscopies. It was found that in the fresh hydrated material, Cu(II) is octahedrally coordinated to six water molecules. This species is located in a cylindrical channel and rotates rapidly at room temperature. Evacuation at room temperature removes three of these water molecules, leaving the Cu (II) coordinated to three water molecules and anchored to oxygens in the channel wall. Dehydration at 45$0^{\circ}C$ produces one Cu (II) species located in the inner surface of a channel as evidenced by broadening of its ESR lines by oxygen. Adsorption of polar molecules such as water, methanol and ammonia on dehydrated CuNa-MCM-41 gallosilicate material causes changes in the ESR spectrum of Cu (II), indicating the complex formation with these adsorbates. Cu (II) forms a complex with six molecules of methanol as evidenced by an isotropic room temperature ESR signal and ESEM data like upon water adsorption. Cu(II) also forms a complex containing four molecules of ammonia based on resolved nitrogen superhyperfine interaction.

• Bulletin of the Korean Chemical Society
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• 제20권9호
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• pp.1067-1072
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• 1999

Structures of unprotonated [(NH3)n+(n = 1-6)] and protonated [NH4+(NH3)n-1(n = 1-6)] ammonia cluster cations have been optimized with ab initio Hartree-Fock (HF) and second-order MФller-Plesset (MP2)/6-31+G ** levels and the harmonic vibrational frequencies have also been evaluated. In unprotonated cluster cations, NH3+ forms as a central core of the first ammonia solvation shell. In protonated cluster cations, NH4+ forms as a central core. In unprotonated dimer and trimer cations, there are two types of isomers (hydrogen-bonded and head-to-head interactions). In both cluster cations, the hydrogen-bonded isomers are more stable. In the hydrogen-bonded dimer cation, the proton transfer reaction takes place from (NH3-HN+H2) to (NH4+-NH2). But in the other unprotonated cluster cations, the proton transfer does not take place. In unprotonated pentamer and hexamer, a NH3+ core has both interactions in a complex. On the other hand, in unprotonated tetramer a core has only the hydrogen-bonded type combined with neutral ammonia molecules. With increasing cluster cation size, the bond lengths [R(NN)] between two nitrogen atoms and the distances [R(N ...H)] of the hydrogen-bond increase reg-ularly. In the calculated infra-red absorption bands for ammonia cluster cations, the characteristic peaks of the bridged NH vibration of the hydrogen-bonded clusters appear near 2500 cm-1 . With increasing size, the peaks shift from 2306 cm-1 to 2780 cm-1 .

• 한국환경과학회지
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• 제8권4호
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• pp.509-514
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• 1999

The sewage sludges and livestock manures, respectively, were composted with sawdust used for control moisture in the static piles system composter. The variations of temperature, pH, moisture, C/N ratio, inorganic content, forms of organic materials and nitrogen, and contents of heavy metals were investigated. The results were summarized as follows ; The temperature for composting the sewage sludges reached the highest temperature of 52$^{\circ}C$, after 3 days and lasted for 7 days, and then went down 3$0^{\circ}C$ after 52 days. In the case of composting livestock manures, the temperature reached to 63$^{\circ}C$ after 10 days, that lasted for 10 days, and then went down gradually. After upsetting the sewage sludges and livestock manures for composting were decreased to 30% and 36%, respectively. The contents of inorganic matters and heavy metals were changed by the characteristics of raw materials but increased gradually during composting process. The total contents of organic materials in the sewage sludges and livestock manures for composting were decreased to 7% and 9%, respectively. The contents of ether extracts, resins, hemicellulose and cellulose were decreased but those of water soluble polysaccharides and lignins were not changed. The total contents of nitrogen in sewage sludges and livestock manures were decreased to 43% and 34%, respectively.

• Journal of Applied Biological Chemistry
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• 제42권1호
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• pp.1-6
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• 1999

Poly-${\beta}$-hydroxybutyrate (PHB) and enzymes related PHB metabolism have been measured in nitrogen-fixing symbiosis of chickpea and cowpea plants. Bacteroids from chickpea and cowpea contained PHB to 0.8% and 43% of their dry weight, respectively, whereas the free-living cells CC 1192 and I 16 produced $285{\pm}55mg$ and $157{\pm}18mg$ of PHB g (dry weight)$^{-1}$. To further understand why chickpea bacteroids contained little PHB, the enzyme activities of PHB metabolism (3-ketothiolase, acetoacetyl-CoA reductase, PHB depolymerase, and 3-hydroxybutyrate dehydrogenase), the TCA cycle (malate dehydrogenase, citrate synthase, and isocitrate dehydrogenase), and related reactions (malic enzyme, pyruvate dehydrogenase, and glutamate:2-oxoglutarate transaminase) were compared in extracts from chickpea and cowpea bacteroids and the respective free-living bacteria. Significant differences were observed between chickpea and cowpea bacteroids and between the bacteroid and free-living forms of CC 1192, with respect to the capacity for some of these reactions. It is indicated that a greater potential for oxidizing malate to oxaloacetate in chickpea bacteroids could be a factor that favors the utilization of acetyl-CoA in TCA cycle rather than for PHB synthesis.

• 아시안잔디학회지
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• 제5권1호
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• pp.1-10
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• 1991

The purpose of the experiment was to determine the effect of nitrogen sources (urea, ammonium sulphate, ammonium nitrate) and potassium sources (potassium chloride, potassium sulphate) on the growth and quality of Zoysia japonica Steud. This experiment was conducted at Seoul City University turf field from 1988 to 1989. The results of this experiment were summarized as follows; 1. Urea and Ammonium sulphate resulted in superior clipping yield compared to ammonium nitrate. The growth of rhizome and stolon increased significantly with urea forms, but ammonium sulphate treated plots exhibited the highest the growth rate of root. 2. Ammonium sulphate showed best turf color rating while ammonium nitrate resulted in the poorest. Prolongation of the green period showed longer in ammonium sulphate and urea treated plots than ammoium nitrate. 3. Urea and ammonium sulphate exhibited superior visible quality and shoot density compared to ammonium nitrate. 4. The uptake of mineral nutrient showed the highest concentration with urea plots. Surface soil pH was allowed to become slightly acid with the ammonium sulphate and potassium sulphate treatments, while the application of N and K sources did not cause significant differences in mineral element content in soil.

• 한국연초학회지
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• 제4권1호
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• pp.51-59
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• 1982

This experiment was conducted to investigate the effects of fertilization level, additional dressing time and form of nitrogen on the growth and formation of Alkaloid in flue-cured tobacco. The results are abstracted as follows. Length and width of harvested leaves, area of a leaf, leaf area per plant, number of harvested leaves, weight of a leaf, and leaf weight of a plant were larger in the $NO_3$-N plot than $NH_4$-N plot. Length, width and area of the middle leaves increased by additional dressing on 7 days before topping, but the dry weight Per unit leaf area of those was decreased. Leaf shape was broaden in additional dressing plots in comparison with 100% of basal dressing plot, but there is no difference among the additional dressing plots. And the smallest leaf shape index was shown at upper leaves in 100% of basal dressing Plot. Leaf weight of a Plaint was the highest in 12kg/10a Plot among $NO_3$-N form and in 12kg/10a plot among $NH_4$-N form. Total Alkaloid content was higher in $NH_4$-N plot between fertilization forms, and highest in 15kg/10a plot among fertilization levels and at the position of middle and upper leaves in the plot of 7 days before topping among additional dressing times.

• 한국토양비료학회지
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• 제44권4호
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• pp.551-558
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• 2011

The aim of this study was to know whether leaf nitrate can be a substitute of total leaf N to justify plant N status and how nitrate influences macro elements uptake and physiological parameters of tomato plants under different nitrogen levels. Leaf nitrate content decreased in low N, while showed similar value with the control in high N, ranging from 55 to $70mg\;g^{-1}$. Differences in nitrate supply led to nitrate-dependent increases in macro elements, particularly cations, while gradual decrease in P. Physiological parameters, photosynthesis rates and antioxidants, greatly responded in N deficient conditions rather than high N, which didn't show any significant differences compared the control. Considering nitrogen forms and physiological parameters, total-N in tomato plants represented positive relation with growth (shoot dry weight), nitrate and $CO_2$ assimilation, whereas negative relation with lipid peroxidation.

• 한국물환경학회지
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• 제18권2호
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• pp.189-199
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• 2002

Nitrogen, in its various forms, can deplete dissolved oxygen levels in receiving waters, stimulate aquatic growth, exhibit toxicity toward aquatic life and affect the suitability of sewage for reuse. Pilot-scale Rotating Biological Contactor(RBC) experiments were conducted to examine biological nitrification, respectively, of municipal sewage with five different internal recirculation ratios of 0, 1, 2, 3, and 4 using the constant hydraulic loading of $205L/m^2{\cdot}day$. The use of internal recirculation improved nitrification on account of the dilution of biodegradable organic carbon in influent sewage down to 15 mg/L of $SBOD_5$ or less. Ammonium nitrogen of $14.3{\pm}2.4%$ was consumed by cellular assimilation without the occurrence of denitrification. The thickness of biofilm didn't seem effect significantly the nitrification and denitrification. Nitrification with internal recirculation was found to occur using hydraulic loading rate of as high as $205L/m^2{\cdot}day$, which was beyond the generally known values of it.

• Bulletin of the Korean Chemical Society
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• 제9권5호
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• pp.292-295
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• 1988

Macrocyclic ligands have been studies as cation carriers in a bulk liquid membrane system. $Cu^{2+}$ has been transported using nitrogen substituted macrocycles as carriers and several transition metal ions($M^{n+}\;=\;Mn^{2+},\;Co^{2+},\;Ni^{2+},\;Cd^{2+},\;Pb^{2+}\;and\;Ag^{+}$) have been transported using $DBN_3O_2,\;DBN_2O_2,\;Me_6N_414C4$ and DA18C6 as carriers in a bulk liquid membrane system. Competitive $Cu^{2+}-M2^+$ transport studies have also been carried out for the same system. In single cation transport experiments, the best macrocyclic ligand for transport is a ligand that gives a moderately stable rather than very stable complex in the extraction. However, when both cations are present in the source phase, the cation which forms the most stable complex with carrier is favored in transport over other cations. Generally, the nitrogen substiituted macrocycles transport $Cu^{2+}$ selectively over $Mn^+$. Ligand structure, equilibrium constant (or stability constant) for complex formation, source phase pH and carrier concentration are also important parameters in transport experiments.

• 한국습지학회지
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• 제15권2호
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• pp.215-222
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• 2013

농업지역의 소하천에 흐르는 하천수는 유역의 농업활동으로 유출된 각종 영양염류의 함량이 높아 호소 유입시 부영양화의 원인이 된다. 본 연구에서는 농업지역의 하천수를 처리하기 위해 조성된 자유수면형 인공습지의 수문학적 유로에 따른 영양염류의 농도를 평가하고자 수행되었다. 습지내 유로에 따른 영양염류의 농도를 평가하기 위한 모니터링은 2009년 4월부터 2011년 11월까지 습지내 유로의 5개 지점에서 수행되었다. 채취된 시료는 유로에 따른 수질변화를 분석하기 위하여 질소와 인에 대한 집중적 분석이 수행되었다. 습지내 TP 저류의 원인을 평가한 결과 수온, DO 및 pH가 큰 영향을 끼치는 것으로 나타났다. 또한 습지내 유입수가 침강지를 통과한 직후 영양염류의 농도가 가장 크게 저감된 것으로 나타났는데, 이는 많은 양의 영양소가 입자와 부착된 형태로 이동하기 때문인 것으로 판단되기에 향후 습지 설계시 침강지의 기능 증대 방안 도입이 중요한 인자인 것으로 평가된다. 그러나 습지내에서 가장 큰 영양염류 저감이 발생한 지점은 유로의 85% 지점인 것으로 나타났다. 이는 습지내 미생물 및 식생흡입에 의한 영향으로 평가되기에 이를 활성화 하기 위한 얕은 습지 및 깊은 습지의 적절한 배치도 인공습지 설계에서 중요한 인자임을 보여주고 있다. 마지막 침전지 부분에서는 영양염류의 농도가 증가하는 것으로 나타났는데, 이는 길어진 체류시간에 의한 퇴적층으로부터 용출이 원인인 것으로 평가되기에 습지설계시 침전지의 적정한 체류시간 확보가 중요한 것으로 나타났다.