• Membrane Journal
• /
• v.26 no.2
• /
• pp.126-134
• /
• 2016

To produce renewable biomethane from biogas, the properties of physical absorbents such as water, methanol, 1-methyl-2-pyrrolidone (NMP), poly(ethylene glycol) dimethylether (PEGDME), and propylene carbonate (PC) were studied, and PC was applied to membrane contactor systems. Among physical absorbents, PC exhibited a high contact angle of $58.3^{\circ}$ on polypropylene surface, and a PC/water mixture (5 wt%) increased the contact angle to $90^{\circ}$. Furthermore, the PC/water mixture presented higher $CO_2$ absorption capacities (0.148-0.157 mmol/g) than that of water (0.121 mmol/g), demonstrating a good property as an absorbent for membrane contactors. Actual operations in membrane contactors using the PC/water mixture resulted in $CO_2$ removal of 98.0-97.8% with biomethane purities of 98.5-98.3%, presenting a strong potential for biogas treatment. However, the PC/water mixture yielded moderate improved in $CO_2$ removal and methane recovery, as compared with water in the membrane contactor operation. This is originated from insufficient desorption processes to reuse absorbent and low $CO_2$ flux of the PC/water absorbent. Thus, it is requiring optimizations of membrane contactor technology including development of absorbent and improvement of operation process.

• Restorative Dentistry and Endodontics
• /
• v.31 no.4
• /
• pp.290-299
• /
• 2006

Objectives: The purpose of this study is to evaluate the effect of ethylene glycol analogs on modulus of elasticity and ultimate tensile strength of moist, demineralized dentin matrix. Methods: Dentin disks 0.5 mrn thick were prepared from mid-coronal dentin of extracted. unerupted, human third molars. 'I' beam and hour-glass shaped specimens were prepared from the disks, the ends protected with nail varnish and the central regions completely demineralized in 0.5M EDTA for 5 days. Ultimate tensile stress (UTS) and low strain modulus of elasticity (E) were determined with specimens immersed for 60 min in distilled water $(H_{2}O)$, ethylene glycol $(HO-CH_{2}-CH_{2}-OH)$, 2-methoxyethanol $(H_{3}CO-CH_{2}-CH_{2}-OH)$, and 1,2-dimethoxyethane $(H_{3}CO-CH_{2}-CH_{3}-OCH_{3})$ prior to testing in those same media. Modulus of elasticity was measured on the same specimens in a repeated measures experimental design. The results were analyzed with a one-way ANOVA on ranks, followed by Dunn's test at ${\alpha}\;=\;0.05$. Regression analysis examined the relationship between UTS or E and hoy's solubility parameter for hydrogen bonding $({\delta}_{h})$ of each solvent. Results: The UTS of demineralized dentin in water, ethylene glycol, 2-methoxyethanol, and 1,2-dimethoxyethane was 24 (3), 30 (5), 37 (6), and 45 (6) MPa, ${\times}$ (SD) N = 10. Low strain E for the same media were 16 (13), 23 (14), 52 (24), and 62 (22) MPa. Regression analysis of UTS vs ${\delta}_{h}$ revealed a significant $(p\;<\;0.0001,\;r\;=\;-0.99,\;R^{2}\;=\;0.98)$ inverse, exponential relationship. A similar inverse relationship was obtained between low strain E vs ${\delta}_{h}\;(p\;<\;0.0005,\;r\;=\;-0.93,\;R^{2}\;=\;0.86)$. Significance: The tensile properties of demineralized dentin are dependent upon the hydrogen bonding ability of polar solvents $({\delta}_{h})$. Solvents with low ${\delta}_{h}$ values may permit new interpeptide H-bonding in collagen that increases its tensile properties. Solvents with high ${\delta}_{h}$ values prevent the development of these new interpeptide H-bonds.

• Korean Journal of Environmental Agriculture
• /
• v.30 no.3
• /
• pp.243-251
• /
• 2011

BACKGROUND: Gypsum($CaSO_4{\cdot}2H_2O$) is known as an ideal amendment to improve soil quality of the reclaimed coastal land. Since gypsum has very high concentration of electron acceptor like ${SO_4}^{2-}$, its application might be effective on reducing $CH_4$ emission during rice cultivation, but its effect has not been studied well. METHODS AND RESULTS: The effect of gypsum on $CH_4$ emission and rice growth characteristics was studied by pot test, which was packed by reclaimed paddy soils collected from Galsa, Hadong, Gyeongnam province. Chemical-grade gypsum was applied in two soils having EC 2.25 and 9.48 dS/m at rates of 0, 0.5, 1.0 and 2.0%(wt/wt). $CH_4$ emission was characterized a week interval by closed chamber method during rice cultivation. $CH_4$ emission rate was significantly decreased with increasing salt accumulation and gypsum application levels. With increasing gypsum application, dissolved ${SO_4}^{2-}$ concentration in the leachate water was significantly increased, which might have suppressed $CH_4$ production in soil. Total $CH_4$ flux was dramatically decreased with increasing gypsum application. In contrast, rice yield was increased with increasing gypsum application and then achieved maximum productivity at 1.0% gypsum application in two soils. CONCLUSION(s): Gypsum is a very good soil amendment to suppress $CH_4$ emission in reclaimed coastal paddy soils, and improve rice productivity and soil properties. The optimum application level of gypsum is assumed at ca. 1% to improve soil productivity with reducing effectively $CH_4$ emission during rice cultivation.

• Journal of The Korean Astronomical Society
• /
• v.34 no.3
• /
• pp.167-179
• /
• 2001

A molecular line survey towards the UC H II region G34.3+0.15 from 155.3 to 165.3GHz has been conducted with the TRAO 14-m radio telescope. Combined with our previous observations from 84.7 to 115.6GHz and 123.5 to 155.3GHz (Paper I), the spectral coverage of this survey in G34.3+0.15 now runs from 85 to 165 GHz. From these latest observations, a total of 18 lines from 6 species were detected. These include four new lines corresponding to ${\Delta}$J = 0, ${\Delta}$K = 1 transitions of the $CH_3OH$ E-type species, and two new lines corresponding to transitions from $SO_2$ and $HC_3N$. These 6 new lines are $CH_3OH$[1(1) - 1(0)E], $CH_3OH$[2(1) - 2(0)E], $CH_3OH$[3(1) - 3(0)E], $CH_3OH$[4(1) - 4(0)E], $SO_2$[14(1, 13) -14(0, 14)] and $HC_3N$[18 -17]. We applied a rotation diagram analysis to derive rotation temperatures and column densities from the methanol transitions detected, and combined with NRAO 12-m data from Slysh et al. 1999. Applying a two-component fit, we find a cold component with temperature 13-16K and column density $3.3-3.4 {\times} 10^{14} cm^{-2}$, and a hot component with temperature 64 - 83K and column density $9.3{\times}10^{14} - 9.7 {\times} 10^{14} cm^{-2}$. On the other hand, applying just a one-component fit yields temperatures in the 47 -62 K range and column densities from $7.5-1.1 {\times} 10^{15} cm^{-2}$.

• Journal of Korea Water Resources Association
• /
• v.49 no.11
• /
• pp.941-949
• /
• 2016

The flow characteristics of the broad-crested side weir considering the levee's side slope of main channel ($ES_{ch}$) was investigated through hydraulic experiment in order to estimate the discharge coefficient equation. For applicability to actual river, levee's side slope of main channel 1:0.5, 1:1 and 1:2 were selected. Experimental results show that the new estimated equation for the discharge coefficient including $ES_{ch}$ is reasonable and effective in actual applications by comparing estimated and measured discharge over side weirs. Through a multiple linear regression analysis the importance of variabes were ordered as $ES_{ch}$ > $h/y_u$ > $L/y_u$ > $Fr_u$. Especially the discharge coefficient equation without $Fr_u$ was suggested, and the high applicability was reviewed by comparing the measured and calculated overflow of broad-chested side weir.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.26 no.5
• /
• pp.335-340
• /
• 2013

In this study, the plasma etching of the TaN thin film with $CH_4/BCl_3/Ar$ gas chemistries was investigated. The etch rate of the TaN thin film and the etch selectivity of TaN to $SiO_2$ was studied as a function of the process parameters, including the amount of $CH_4$. X-ray photoelectron spectroscopy (XPS) and Field-emission scanning electron microscopy (FE-SEM) was used to investigate the chemical states of the surface of the TaN thin film.

• Journal of Microbiology and Biotechnology
• /
• v.1 no.2
• /
• pp.136-141
• /
• 1991

Optimum culture conditions for the formation of nitrile hydratase by Brevibacterium sp. CH2 were investigated. Addition of ferric and ferrous ions greatly increased the nitrile hydratase formation. The effects of nitriles, amides, and acids as an inducer on the formation of nitrile hydratase were investigated. Isobutyramide was the best inducer among the tested compounds. When Brevibacterium sp. CH2 was cultivated for 23 h at $30^{\circ}C$ in a optimized medium containing 15 g of glucose, 5 g of bacto peptone, 3 g of yeast extract, 3 g of malt extract, 1 g of $KH_2$$PO_4$, 1 g of $K_2$$HPO_4$, 1 g of NaCl, 0.5 g of isobutyramide, 0.2 g of MgSO$_4$ㆍ7$H_2O$, and 0.02g of $FeSO_4$ㆍ$7H_2$O per liter of distilled water with pH controlled at 7.1, the maximum total activity was 665 units/ml of the culture broth and the specific activity was 70 units/mg of the dry cells. The medium optimization increased the specific activity of Brevibacterium sp. CH2 2.2 times.

• Korean Journal of Veterinary Research
• /
• v.14 no.1
• /
• pp.77-90
• /
• 1974

Hemolytic reaction of normal fresh chicken serum on sheep erythrocytes was studied and the following experimental results were obtained and summarized. 1. Chicken sera, 258 (78%) out of 344 samples showed hemolytic activity on sheep erythrocytes. 2. Distribution of a different hemolytic titer of chicken sera was not dependent to sex and age difference of test chicken. 3. Hemolytic activity of serum component obtained from normal fresh chicken was heat inactivated at $56^{\circ}C$. 30 minutes heating. 4. The most enhanced hemolytic activity of chicken serum on sheep erythrocytes was observed at the incubation temperature of $46^{\circ}C$. 5. The most effective pH for the hemolytic reaction of chicken serum on sheep erythrocytes was observed at 7.0, and pH 6.0 or 8.5 resulted less or no hemolysis. 6. Hemolytic reaction of chicken serum and sheep erythrocytes required Mg⧻ and Ca⧻ ions as, co-factor, and the former was required more compared to the latter. 7. Hemolytic activity of chicken serum was observed in ChC 2, 4 fraction but not in ChC 1, 3, ChC 3, 4, ChC 1, 2, 4 and ChC 1, 2, 3 fractions. 8. In electron micrography, morphological changes of sheep erythrocyte membrane by normal chicken serum was similar to that of immune hemolysis: that was, the hemolytic hole was circular and it was surrounded with a white ring. 9. Electron micrography of morphological changes on sheep erythrocyte membrane indicated that the size of hemolytic hole and white ring were functional to the chicken serum concentration used and reaction time.

• Korean Journal of Food Science and Technology
• /
• v.4 no.2
• /
• pp.72-76
• /
• 1972

Seven new hydroxyamine derivatives of 2,2'-methylene bis(3,4,6-trichloroacetoxy benzene) were synthesized by the Mannich reactions. 13 strains of microorganisms were tested for sensitivity to these derivatives by both paper disk method and tube dilution method. Of these compounds, -NHOH compound displays the most effective antimicrobial activity in vitro against Brevibacterium ammoniagenes, Staphylococcus aureus and Bacillus subtilis. Its minimal inhibitory concentration is $1.6{\mu}g/ml$ for Brevibacterium ammoniagenes, and $5{\mu}g/ml$ for Staphylococcus aureus and Bacillus subtilis.

• Food Science of Animal Resources
• /
• v.41 no.1
• /
• pp.59-70
• /
• 2021

A method for simultaneous detection of fipronil (F) and its metabolites fipronil desulfinyl (FD), fipronil sulfide (FS), fipronil sulfone (FSO) in chicken eggs was applied and validated. It includes single-step, cheap, effective, rugged, safe-based method (SinChERS) for sample preparation and ultra high performance liquid chromatography coupled with mass spectrometry (UHPLC-MS/MS) for chemical analysis. Results suggested that formic acid enhanced the recovery of 4 target residues and 1% supplementation to acetonitrile gained higher recoveries than that of 5%. SinChERS integrated extraction and clean-up steps into one, with shorter time (1.5 h) to operate and higher recoveries (97%-100%) than HLB, Envi-Carb-NH2 and quik-easy-cheap-effective-rugged-safe method (QuEChERS), and it consumed the smallest volume of extracting solvent (10 mL) as QuEChERS. Quantitative analyses using external standard method suggested the linear ranges of 4 target compounds were 1-20 ㎍/L with R2 >0.9947. The limit of detection (S/N>3) and quantification (S/N>10) were 0.3 ㎍/kg and 1 ㎍/kg. Recoveries ranged from 89.0% to 104.4%, and the relative standard deviations (n=6) at 1, 10, and 20 ㎍/kg were lower than 6.03%. Thirty batches of domestic eggs (500 g each) were detected by the established SinChERS-based UHPLC-MS/MS and no target residues were detected in all samples. The method developed in this study is a rapid, sensitive, accurate and economic way for multi-residue analysis of fipronil and its metabolites in eggs.