• Asian Journal of Atmospheric Environment
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• v.4 no.2
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• pp.97-105
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• 2010

A quantitative single particle analytical technique, denoted low-Z particle electron probe X-ray microanalysis (low-Z particle EPMA), was applied to characterize particulate matters collected at two underground subway stations, Jegidong and Yangje stations, in Seoul, Korea. To clearly identify the source of the indoor aerosols in the subway stations, four sets of samples were collected at four different locations within the subway stations: in the tunnel; at the platform; near the ticket office; nearby outdoors. Aerosol samples collected on stages 2 and 3 ($D_p$: $10-2.5\;{\mu}m$ and $2.5-1.0\;{\mu}m$, respectively) in a 3-stage Dekati $PM_{10}$ impactor were investigated. Samples were collected during summertime in 2009. The major chemical species observed in the subway particle samples were Fe-containing, carbonaceous, and soil-derived particles, and secondary aerosols such as nitrates and sulfates. Among them, Fe-containing particles were the most popular. The tunnel samples contained 85-88% of Fe-containing particles, with the abundance of Fe-containing particles decreasing as the distances of sampling locations from the tunnel increased. The Fe-containing subway particles were generated mainly from mechanical wear and friction processes at rail-wheel-brake interfaces. Carbonaceous, soil-derived, and secondary nitrate and/or sulfate particles observed in the underground subway particles likely flowed in from the outdoor environment by human activities and the air-exchange between the subway system and the outdoors. In addition, since the platform screen doors (PSDs) limit air-mixing between the tunnel and the platform, samples collected at the platform at the Yangjae station (with PSDs) showed a marked decrease in the relative abundances of Fe-containing particles compared to the Jegidong station (without PSDs).

• Journal of the Korean Chemical Society
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• v.17 no.3
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• pp.224-228
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• 1973

In the fermentation for preparation of petroprotein by Rhodotorula sp. in $C_{12}{\sim}C_{14}$n-alkane mixture it was investigated how the effects due to the difference of chemical form of the nitrogen sources are, that is, how the inorganic nitrogen sources such as nitrates and ammonium salts and organic nitrogen source such as urea effect on the view of fermentation time and yield and how the ratios of nitrogen to carbon with $NaNo_3$ effect. Then following results were obtained: the time required to maximum growth, when $NaNo_3$ or $(NH_4)_2SO_4$ was used as nitrogen source, was 40 hrs. and 45 hrs., respectively, but when urea was used, it was 66 hrs. much longer than above nitrogen sources. On the view of yield, however, in use of the both inorganic sources, when the yield is represented as consumption of 0.1 N-NaOH, it was 0.36 and 0.38 ml, respectively, but, in the case of urea, it amounted to 0.78 ml. In the effect of the ratios of nitrogen to carbon in medium, when n-alkane mixture was added in 1 % (vol.) and N/C with $NaNo_3$ was 0.2 the best results were obtained and generally the higher the value of the ratio the better growth effects were shown.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.6
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• pp.727-735
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• 2007

The use of water by cities is increasing owing to industrialization, the concentration of population, and the enhancement of the standard of living. Accordingly, the amount of waste water is also increasing, and the degree of pollution of the water system is rising. In order to solve this problem, it is necessary to remove organisms and suspended particles as well as the products of eutrophication such as nitrates and phosphates. This study developed a high-end treatment engineering solution with maximum efficiency and lower costs by researching and developing a advanced treatment engineering solution with the use of Biosorption. As a result, the study conducted a test with a $50m^3/day$ Pilot Scale Plant by developing treatment engineering so that only the secondary treatment satisfies the standard of water quality and which provided optimal treatment efficiency along with convenient maintenance and management. The removal of organisms, which has to be pursued first for realizing nitrification during the test period, was made in such a way that there would be no oxidation by microorganisms in the reactor while preparing oxygen as an inhibitor for the growth of microorganism in the course of moving toward the primary settling pond. The study introduced microorganisms in the endogeneous respiration stage to perform adhesion, absorption, and filtering by bringing them into contact with the inflowing water with the use of a sludge returning from the secondary settling pond. Also a test was conducted to determine how effective the microorganisms are as an inner source of carbon. The HRT(Hydraulic Retention Time) in the nitrification tank (aerobic tank) could be reduced to two hours or below, and the stable treatment efficiency of the process using the organisms absorbed in the NAR reactor as a source of carbon could be proven. Also, given that the anaerobic condition of the pre-treatment tank becomes basic in the area of phosphate discharge, it was found that there was excellent efficiency for the removal of phosphate when the pre-treatment tank induced the discharge of phosphate and the polishing reactor induced the uptake of phosphate. The removal efficiency was shown to be about 94.4% for $BOD_5$. 90.7% for $COD_{Cr}$ 84.3% for $COD_{Mn}$, 96.0% for SS, 77.3% for TN, and 96.0% for TP.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.4
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• pp.564-572
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• 2013

Two trials were conducted to investigate the effect of decreasing the crude protein (CP) content of diets for finishing pigs containing two levels of available lysine on nutrient digestibility, nitrogen (N) balance and production performance. Ten finishing diets containing five levels of CP (on average 144, 155, 168, 182 and 193 g/kg fresh basis) and two levels of available lysine (6.9 and 8.2 g/kg fresh basis) were formulated. The diets were offered to pigs on a performance trial (n = 800 Large White (LW)${\times}$Landrace (LR) pigs) from 10 wk of age until finish at 21 wks+5 d of age. Average daily gain (ADG), average daily feed intake (ADFI) and feed conversion ratio (FCR) were calculated. In addition, a digestibility/N balance trial was conducted using pigs (n = 80 $LW{\times}LR$) housed in metabolism crates. Digestibility of dry matter (DM), CP, oil, fibre and energy was determined. N balance values were determined through analysis of N content of urine and faeces ('as determined'). N balance values were also calculated using ADG values and assuming that 16% of growth is protein deposition ("as calculated"). Pig performance was poor between 10 and 13 wk of age which indicated that the dietary treatments were nutritionally inadequate for pigs less than 40 kg. There was a significant (p<0.01) quadratic effect of increasing CP level on feed intake, ADG and FCR from 10 to 13 wk which indicated that the lower CP levels did not supply adequate levels of essential or non-essential amino acids. There was no effect of increasing available lysine level throughout the early period, which in conjunction with the response in older pigs, suggested that both 8.2 and 6.9 g/kg available lysine were insufficient to drive optimum growth. There was a positive response (p<0.05) to increasing available lysine level from 13 wk to finish which indicated that 6.9 g/kg available lysine was not adequate for finishing pigs. Energy digestibility decreased with decreasing CP level of diets containing 6.9 g/kg available lysine which may be attributed to the higher fibre content of the lower CP diets. Nitrogen excretion (g/d) was lowered when dietary CP was reduced regardless of whether the values were determined through balance or calculated using ADG. Calculated N excretion decreased linearly (p<0.001) and quadratically (p<0.001) with decreasing dietary CP content. When the N balance figures calculated in this study were compared with those quoted in the Northern Ireland and English Nitrates Directive Action Programmes, N excretion was less per pig (wean to finish) offered a 169 g/kg CP, 8.2 g/kg available lysine diet (2.39 kg vs 3.41 kg (Northern Ireland) and 2.93 kg (England)).

• Ocean Science Journal
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• v.40 no.3
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• pp.167-176
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• 2005

A time-series sediment trap was deployed at 1,034 m water depth in the eastern Bransfield Strait for a complete year from December 25, 1998 to December 24, 1999. About 99% of total mass flux was trapped during an austral summer, showing distinct seasonal variation. Biogenic particles (biogenic opal, particulate organic carbon, and calcium carbonate) account for about two thirds of annual total mass flux $(49.2\;g\;m^{-2})$, among which biogenic opal flux is the most dominant (42% of the total flux). A positive relationship (except January) between biogenic opal and total organic carbon fluxes suggests that these two variables were coupled, due to the surface-water production (mainly diatoms). The relatively low $\delta^{13}C$ values of settling particles result from effects on C-fixation processes at low temperature and the high $CO_2$ availability to phytoplankton. The correspondingly low $\delta^{l5}N$ values are due to intense and steady input of nitrates into surface waters, reflecting an unlikely nitrate isotope fractionation by degree of surface-water production. The $\delta^{l5}N$ and $\delta^{l3}C$ values of sinking particles increased from the beginning to the end of a presumed phytoplankton bloom, except for anomalous $\delta^{l5}N$ values. Krill and the zooplankton fecal pellets, the most important carriers of sinking particles, may have contributed gradually to the increasing $\delta^{l3}C$ values towards the unproductive period through the biomodification of the $\delta^{l3}C$ values in the food web, respiring preferentially and selectively $^{12}C$ atoms. Correspondingly, the increasing $\delta^{l5}N$ values in the intermediate-water trap are likely associated with a switch in source from diatom aggregates to some remains of zooplankton, because organic matter dominated by diatom may be more liable and prone to remineralization, leading to greater isotopic alteration. In particular, the tendency for abnormally high $\delta^{l5}N$ values in February seems to be enigmatic. A specific species dominancy during the production may be suggested as a possible and speculative reason.

• Economic and Environmental Geology
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• v.43 no.1
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• pp.43-52
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• 2010

The geochemical and nitrogen isotopic analyses for shallow groundwater of Ogcheon area were carried out to characterize the geochemical characteristics of the groundwater and to identify the source of nitrate. Groundwater shows a neutral pH to weakly alkalic condition with pH values ranging from 6.9 to 8.4. The average of EC, Eh and DO is $344.2\;{\mu}s/cm$, 195 mV, 4 mg/L, respectively. According to piper diagram, chemical composition of groundwater is dominantly characterized by Ca-$HCO_3$ type. On the other hand, groundwater type in the study area include Ca-Cl+$NO_3$ type that were highly influenced by agricultural activities. $NO_3$-N concentration of the collected samples(n=45) range from 12.4 to 34.2 mg/l. These data show that the $NO_3$-N concentration exceeds Korea Drinking Water Standard (10 mg/l). The $\delta^{15}N-NO_3$ values range from $2.7^{\circ}/_{\circ\circ}$ to $18.8^{\circ}/_{\circ\circ}$. The enrichments of heavy isotope in the groundwater indicate that major origin of nitrate pollution were associated with animal and human waste. Also the denitrification may have partly contributed as one of the sources of nitrogen.

• Journal of Korean Society for Atmospheric Environment
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• v.13 no.2
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• pp.147-159
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• 1997

One of the most critical problems associated with filter-pack data comparisons from various field networks is the use of different sampling flow rates. In this field study, the effects of various filter-pack(FP) sampling conditions were examined. Experiments were conducted to evaluate the effects of varying sampling flow rates (1.5 to 10 sLpm) on measured concentrations of dry acid deposition species. Collocated FP samples were also collected to determine sampling and analysis data reproducibility. Ambient air samples were collected simultaneously for the seven day durations at varous flow rate. The chemical species measured were sulfur dioxide ($SO_2$), particulate sulfate(P-$SO_{4}^{2+}$), nitric acid ($HNO_3$), and particulate nitrate (P-$NO_{3}^{-}$). The results indicated that the collocated samples can be measured reproducibly and that sampling bias for the species measured is not significant. It was concluded that variations in the flow rates (1.5 to 10 sLpm) did not significantly affect the concentration of the species of interest. Although the results were not significantly different between different flow rates, artifacts were more likely to occur at high flow conditions (>5 sLpm) (e.g., via volatilization of particulate nitrates) than at low flow conditions(<5 sLpm).

• Journal of the Korean Chemical Society
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• v.33 no.3
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• pp.326-331
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• 1989

Superconducting fiber of high Tc $YBa_2Cu_3O_{7-{\sigma}}$ was successfully prepared by the sol-gel method. The stoichiometric mixture of Y, Ba and Cu nitrates was dissolved in water, to which citric acid solution was added. Then ammonium hydroxide was added to the mixture in order to increase the pH to a value between 5.8 and 6.2. The mixture was heated carefully to form a homogeneous colloid sol at 358 K. The solution was viscous enough to draw a long gel fiber, which was then heated at 1223K for 8 hrs. under oxygen partial pressure of $Po_2$ = 1 atm., cooled slowly and annealed at 723K for 13 hrs.. The reacted superconducting sample maintained a fiber form with some shrinkage of its volume. The superconducting transition temperatures (Tc, onset and Tc, offset) of $YBa_2Cu_3O_{7-{\sigma}}$ have been determined to be approximately 95K and 82K, respectively. The superconducting phase was also confirmed by Meissner effect at liquid nitrogen boiling temperature.

• Preventive Nutrition and Food Science
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• v.8 no.4
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• pp.321-329
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• 2003

In order to provide data on N-nitrosamine (NA) and sanitation in fish available in domestic markets, this study analyzed the levels of NA and its precursors in 9 samples of sea breams and yellow croakers, 12 samples of red-flesh fish, 38 samples of white fish, 5 samples of Alaska pollacks and cod, and 8 species of imported fish. Sea breams and yellow croakers had nitrite concentrations ranging from non-detectable (ND) to 7.4 mg/kg, red fish ND to 5.3 mg/kg, white fish ND to 18.7 mg/kg, Alaska pollacks 0.3 to 2.2 mg/kg, and imported fish from 0.4 to 12.8 mg/kg. Nitrates in sea breams and yellow croakers ranged from 1.2 to 41.19 mg/kg, red fish 0.6 to 26.1 mg/kg, white fish 4.3 to 75.9 mg/kg, Alaska pollacks 0.4 to 3.1 mg/kg, and imported fish ND to 16.0 mg/kg. DMA concentrations were 69.8 to 219.9 mg/l00 g in sea breams and yellow croakers, 4.1 to 336.3 mg/l00 g in red fish, 1.3 to 331.9 mg/l00 g in white fish, 15.7 to 312.3 mg/l00 g in Alaska pollacks, and 1.0 to 71.8 mg/l00 g in imported fish. TMA concentrations in sea breams and yellow croakers, red fish, white fish, Alaska pollacks and imported fish were 43.8∼496.2, 12.3∼127.0, 2.0∼525.9, 15.4∼122.4, and 4∼70.6 mg/l00 g, respectively. For NA in fish distributed in local markets, only N-nitro-sodimethylamine (NDMA) was detected, and its concentrations ranged from 4.7 to 73.7 $\mu\textrm{g}$/kg in sea breams and yellow croakers, 2.2 to 56.5 $\mu\textrm{g}$/kg in red fish, ND to 143 $\mu\textrm{g}$/kg in white fish, 3.8 to 33.3 $\mu\textrm{g}$/kg in Alaska pollacks, and 2.1 to 102.2 $\mu\textrm{g}$/kg in imported fish.

• Korean Journal of Agricultural Science
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• v.47 no.3
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• pp.597-604
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• 2020

Exposure to heat stress (HS) has negative effects on pig production and health. Plasma concentrations of amino acids (AAs) can be used as indicators of HS. Therefore, this study was conducted to evaluate the effect of acute HS on feed intake, water drink, and plasma AAs in pigs. A total of 6 growing pigs (n = 6, 3 boars and 3 gilts) were raised in thermal neutral (TN; 25℃) conditions for the 5-d adaptation period as a control. After the adaptation, pigs were exposed to HS at 33℃ (HS33) for 24 h. All the pigs were fed the same diet formulated to meet or exceed predicted requirements during the whole experimental period. Blood samples were collected after the adaptation and heat treatment to verify the AAs. Measurements were the average daily feed intake (ADFI), average daily water intake (ADWI), water loss, tumor necrosis factor (TNF)-α, nitrate, total nitric oxide, and AAs in the plasma samples. Data were analyzed using the PROC GLM of SAS. HS33 had a lower ADFI (p < 0.05) and a tendency for an increased ADWI and water loss compared to TN. The level of TNF-α was significantly decreased (p < 0.05) in HS33. HS33 had a lower concentration of histidine and sarcosine compared to TN; however, there were no differences in the levels of nitrates and total nitric oxide. In conclusion, the results of this study show the differential effect of HS on the plasma concentration of AAs. We expect that the changed AAs could be potential indicators of HS.