In this study, combined effect of airflow rate, $TiO_2$ concentration, solution pH and $Ca^{+2}$ addition on HA (humic acid) fouling in submerged, photocatalytic hollow-fiber microfiltraiton was investigated systematically. Results showed that UV irradiation alone without $TiO_2$ nanoparticles could reduce HA fouling by 40% higher than the fouling obtained without UV irradiation. Compared to the HA fouling without UV irradiation and $TiO_2$ nanoparticles, the HA fouling reduction was about 25% higher only after the addition of $TiO_2$ nanoparticles. Both adsorptive and hydrophilic properties of $TiO_2$ nanoparticles for the HA can be involved in mitigating membrane fouling. It was also found that the aeration itself had lowest effect on fouling mitigation while the HA fouling was affected significantly by solution pH. Transient behavior of zeta potential at different solution pHs suggested that electrostatic interactions between HA and $TiO_2$ nanoparticles should improve photocatalytic efficiency on HA fouling. $TiO_2$ concentration was observed to be more important factor than airflow rate to reduce HA fouling, implying that surface reactivity on $TiO_2$ naoparticles should be important fouling mitigation mechanisms in submerged, photocatalyic microfiltraiton. This was further supported by investigating the effect of $Ca^{+2}$ addition on fouling mitigation. At higher pH (= 10), addition of $Ca^{+2}$ can play an important role in bridging between HA and $TiO_2$ nanoparticles and increasing surface reactivity on nanoparticles, thereby reducing membrane fouling.
Recently, Psychrobacter sp. ArcL13 strain showing the extracellular lipase activity was isolated from the Chuckchi Sea of the Arctic Ocean. However, due to the low expression levels of the enzyme in the natural strain, the production of recombinant lipase is crucial for various applications. Identification of the gene for the enzyme is prerequisite for the production of the recombinant protein. Therefore, in the present study, a novel lipase gene (ArcL13-Lip) was isolated from Psychrobacter sp. ArcL13 strain by gene prospecting using PCR, and its complete nucleotide sequence was determined. Sequence analysis showed that ArcL13-Lip has high amino acid sequence similarity to lipases from bacteria of some Psychrobacter genus (84-90%) despite low nucleotide sequence similarity. The lipase gene was cloned into the bacterial expression plasmid and expressed in E. coli. SDS-PAGE analysis of the cells showed that ArcL13-Lip was expressed as inclusion bodies with a molecular mass of about 35 kDa. Refolding was achieved by diluting the unfolded protein into refolding buffers containing various additives, and the highest refolding efficiency was seen in the glucose-containing buffer. Refolded ArcL13-Lip showed high hydrolytic activity toward p-nitrophenyl caprylate and p-nitrophenyl decanoate among different p-nitrophenyl esters. Recombinant ArcL13-Lip displayed maximal activity at $40^{\circ}C$ and pH 8.0 with p-nitrophenyl caprylate as a substrate. Activity assays performed at various temperatures showed that ArcL13-Lip is a cold-active lipase with about 40% and 73% of enzymatic activity at $10^{\circ}C$ and $20^{\circ}C$, respectively, compared to its maximal activity at $40^{\circ}C$.
Koh, Won-Jung;Kwon, O Jung;Yu, Chang-Min;Jeon, Kyeongman;Kim, Kyung Chan;Lee, Byoung-Hoon;Hwang, Jung Hye;Kang, Eun Hae;Suh, Gee Young;Chung, Man Pyo;Kim, Hojoong
Tuberculosis and Respiratory Diseases
/
v.56
no.3
/
pp.248-260
/
2004
Background : As an effective regimen for isoniazid (INH)-resistant pulmonary tuberculosis, several treatment regimens have been recommended by many experts. In Korea, a standard regimen has not been established for INH-resistant tuberculosis, and the treatment by individual physicians has been performed on an empirical bases. The purpose of the present study was to retrospectively describe the treatment characteristics and evaluate the treatment outcomes of patients with INH-resistant tuberculosis. Materials and Methods : Sixty of 69 patients reported to have INH-resistant tuberculosis from 1994 to 2001 were retrospectively analyzed. Exclusion criteria included: death from other causes, with the exceptions of tuberculosis and incomplete treatment, including a patient's transfer-out. Results : A previous tuberculosis history was found in 28 (46.7%) patients. The sputum smear for acid-fast bacilli was positive in 44 (73.3%) patients, and 30 (50.0%) had cavitary disease. Streptomycin resistance coexisted in 25.0% of isolates. INH was to be prescribed continuously, even after INH resistance was reported, in 86.0% of patients. The treatment regimens were diverse between the patients according to drug regimen composition and treatment duration. The most frequent prescribed regimen included rifampin, ethambutol and pyrazinamide, with and without INH, for the full 12-month term of treatment. Treatment failure occurred in 13 (21.7%) patients. Cavitary disease (p=0.005) and a treatment regimen with second-line drugs, excluding rifampin (p=0.015), were associated with treatment failure. One patient experienced a relapse. Conclusions : Standardized treatment guidelines will be needed in Korea to improve the treatment efficacy for INH-resistant tuberculosis.
Journal of the Korea Institute of Building Construction
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v.9
no.4
/
pp.55-61
/
2009
Recently, the number of high-rise buildings being built in Korea by major construction companies for residential and commercial use has been increasing. When constructing a high-rise building, it is necessary to apply massive amounts of concrete to form a mat foundation that can withstand the huge load of the upper structure. However, it is of increasing concern that due to limitations in terms of the amount of placing equipment, available job-sites and systems for mass concrete placement in the construction field, it is not always possible to place a great quantity of concrete simultaneously in a large-scale mat foundation, and for this reason consistency between placement lift cannot be secured. In addition, a mat foundation Is likely to crack due to the stress caused by differences inhydration heat generation time. To derive a solution for these problems, this study provides test results of a hydration heat crack reduction method by applying placement lift change and setting time control with a super retarding agent for mass concrete in a large-scale mat foundation. Mock-up specimens with different mixtures and placement liftswere prepared at the job-site of a newly-constructed high-rise building. The test results show that slump flow of concrete before and after adding the super retarding agent somewhat Increases as the target retarding time gets longer, while the air content shows no great difference. The setting time was observed to be retarded as the target retarding time gets longer. As the target retarding time gets longer, compressive strength appears to be decreased at an early stage, but as time goes by, compressive strength gets higher, and the compressive strength at 28 days becomes equal or higher to that of plain concrete without a super retarding agent. For the effect of placement lift change and super retarding agent on the reduction of hydration heat, the application of 2 and 4 placement lifts and a super retarding agent makes it possible to secure consistency and reduce temperature difference between placement lifts, while also extending the time to reach peak temperature. This implies that the possibility of thermal crack induced by hydration heat is reduced. The best results are shown in the case of applying 4 placement lifts.
This study was performed to investigate the effects of green tea on fat metabolism of rats and prevention to cardiovascular disease in drinking green tea. Male Spague-Dawley rats were divided into seven groups consisting of the control, lard and cholestrol, aqueous green tea at the level of 1% and 3%. After 4 weeks of feeding serum lipid levels were measured for experimental rats, and analyzed the total cholesterol (TC), HDL-cholesterol (HDL-C), triglyceride (TG), phospholipid (PL). And total lipid (TL) to Folch method, lipid deposition to oil red O staining on liver tissue. The results are as follows: Total cholesterol (TC) decreased by administration of 1% aqueous green tea group and increased addition to lard and cholesterol (LC) group as compared to each groups (p<0.05). HDL-cholestrol in serum increased by administration of la aqueous green tea group (1G) and decreased to the control group, 1% aqueous green tea (L-1G) added lard group (p<0.05). Triglyceride (TG) decreased by administration of 3% aqueous green tea groups (L-3G, LC-3G) and increased by lard and cholesterol group (LC) (p<0.01). Phospholipid(PL) decreased by administration of 3% aqueous green tea added lard and cholesterol group (LC-3G) and increased by control group, lard and cholestrol group (LC) (p<0.05). Total lipid of liver decreased by administration of aqueous green tea at the level of 1% group and increased by LC group (p<0.01). The fat deposition of liver was increased in fat diet groups and decrease in the drink green tea of some but did not showed significant differences from concentration of the green tea.
Kim, Yu-Na;Jeong, Yeon-Kyu;Kim, Mu-Chan;Kim, Sung-Bae;Chang, Yong-Keun;Chi, Won-Jae;Hong, Soon-Kwang;Kim, Chang-Joon
Microbiology and Biotechnology Letters
/
v.40
no.1
/
pp.1-9
/
2012
This study's aim was to isolate microorganisms producing agarase with a high activity, with possible applications in improving the performance of the pretreatment processes for bioethanol production. Marine algaes were collected from the south coast of Korea, from which three kinds of microorganisms were isolated. After a 4-day culture of these strains at $25^{\circ}C$, crude enzymes were obtained from culture supernatant or cell-free extract by ammonium sulfate precipitation and membrane dialysis. Agarase activity was observed in these crude enzymes. Notably higher specific activity was observed in the crude enzyme obtained from the culture supernatant rather than that from the cell-free extract. This indicates that a secreted enzyme has a much greater activity than a cellular enzyme. Crude enzymes from the GNUM08122 strain were inferred to have ${\alpha}$-agarase activity because release of p-nitrophenol was observed, possibly due to the cleavage of p-nitrophenyl-${\alpha}$-D-galactopyranoside. The 16S rRNA sequence of GNUM08122 showed a close relationship to Pseudoalteromonas issachenkonii KMM 3549 (99.8%) and Pseudoalteromonas tetraodonis IMA 14160 (99.7%), which led us to assign it to the genus Pseudoalteromonas. Biochemical and physiological study revealed that this strain can grow well at $40^{\circ}C$ under a wide range of pH (pH 4~8) in high-salt conditions (10% NaCl).
Park, Mirye;Kim, Z-Hun;Nam, Seung Won;Lee, Sang Deuk;Yun, Suk Min;Kwon, Dae Ryul;Lee, Chang Soo
Microbiology and Biotechnology Letters
/
v.48
no.2
/
pp.205-214
/
2020
Cyanobacteria are microorganisms which have important roles in the nitrogen cycle due to their ability to fix nitrogen in water and soil ecosystems. They also produce valuable materials that may be used in various industries. However, some species of cyanobacteria may limit the use of water resources by causing harmful algal blooms in water ecosystems. Many culture collection depositories provide cyanobacterial strains for research, but their systematic preservation is not well-developed in Korea. In this study, we developed a method for the cryopreservation of the cyanobacteria Trichormus variabilis (syn. Anabaena variabilis), using alginate microcapsules. Two approaches were used for the experiments and their outputs were compared. One of the methods involved the cryopreservation of cells using only a cryoprotectant and the other used the cryoprotectant within microcapsules. After cryopreservation for 35 days, cells preserved with both methods were successfully regenerated from the initial 1.0 × 105 cells/ml to a final concentration of 6.7 × 106 cells/ml and 1.1 × 107 cells/ml. Irregular T. variabilis shapes were found after 14 days of regeneration. T. variabilis internal structures were observed by transmission electron microscopy (TEM), revealing that lipid droplets were reduced after cryopreservation. The expression of the mreB gene, known to be related to cell morphology, was downregulated (54.7%) after cryopreservation. Cryopreservation using cryoprotectant alone or with microcapsules is expected to be applicable to other filamentous cyanobacteria in the future.
Journal of Korean Society of Environmental Engineers
/
v.33
no.1
/
pp.39-46
/
2011
NO oxidation is an important prerequisite step to assist the selective catalytic reduction (SCR) at low temperatures ($<200^{\circ}C$). Therefore, we conducted the lab- and bench-scales experiments appling the sodium chlorite powder ($NaClO_2(s)$) for the oxidation of NO to $NO_2$ and the carbon-based catalyst for the reduction of $NO_x$ and $SO_2$; the lab- and bench-scales experiments were conducted in laboratory and iron-ore sintering plant, respectively. In the lab-scale experiment, known concentrations of $NO_x$ (200 ppm), $SO_2$ (75 ppm), $H_2O$ (10%) and $NH_3$ (400 ppm) in 2.6 L/min were introduced into a packed-bed reactor containing $NaClO_2(s)$, then gases produced by the reaction with $NaClO_2(s)$ were fed into the carbon-based catalyst (space velocity = $2,000hr^{-1}$) at $130^{\circ}C$. In the bench-scale experiment, flue gases of $50Nm^3/hr$ containing 120 ppm NO and 150 ppm $SO_2$ were taken out from the duct of iron-ore sintering plant, then introduced into the flow reactor; $NaClO_2(s)$ were injected into the flow reactor using a screw feeder. Gases produced by the reaction with $NaClO_2(s)$ were introduced into the carbon-based catalyst (space velocity = $1,000hr^{-1}$). Results have shown that, in both lab- and bench-scales experiments, NO was oxidized to $NO_2$ by $NaClO_2(s)$. In addition, above 90% of $NO_x$ and $SO_2$ removal were obtained at the carbon-based catalyst. These results lead us to suggest that the combination of $NaClO_2(s)$ with the carbon-based catalyst has the potential to achieve the simultaneous removal of $NO_x$ and $SO_2$ at low temperature ($<200^{\circ}C$).
Journal of Korean Society of Environmental Engineers
/
v.33
no.1
/
pp.47-53
/
2011
$SF_6$ (Sulfur hexafluoride) possesses high GWP (Global Warming Potential) as sepcified by the IPCC (Intergonvernmental Panel of Climate Change). Recently, the recovery-separtion of $SF_6$ research area, including permeation properties studies using various membrane's materials and the practical operation of recovery-separtion using membrane of waste $SF_6$ gas is in the initial state. The separation efficiency of a single $SF_6$ and waste $SF_6$ mixture was evaluated using a PSF (polysulfone), PC (tetra-bromo polycarbonate) and PI (polyimide) hollow fiber membranes. According to the results of single gases permeation properties, PI membrane has the highest permselectivity of $N_2$ gas in $N_2/SF_6$ gas. Under the condition of P=0.5 MPa, the highest concentration of recovered $SF_6$ is 95.6 vol % in the separation experiment of $SF_6/N_2$ mixture gas by PC membrane. Under the operation pressure of P=0.3 MPa at a fixed retentate flow rate fixed of 150 cc/min, the maximum recovery efficiency of $SF_6$ is up to 97.8% by PSF membrane. From the results above, it is thought that the separation and recovery technique of $SF_6$ gas using membrane will be used as the representative eco-technology in the $SF_6$ gas treatment in the future.
To select the viable alternative substrates among the variable organic substrates for productivity enhancement and production cost-reduction of oyster mushroom in bottle culture, this study was carried out at mushroom research institute of GGRDA in 2007. In bottle culture of oyster mushroom (Plerutus ostreatus), the seedcakes of rape (RS), soybean (SS), coconut (CCS), and kapok (KS) were examined as substitute of cotton seedcake which was primary nutritive material of mushroom growing substrate. The chemical properties of substrate mixed with kapok seedcake is similar to the mixture with cotton seedcake in T-C, T-N, C/N ratio, and other nutrients. Mixed growing substrate containing cotton seedcake and kapok seedcake was superior to other mixtures 99.2% and 99.5%, respectively in spawning ratio and was faster mycellium growth in column test than that of soybeen seedcake, cotton + soybeen seedcake, and coconut seedcake. The period required in first pin-heading was 1-2 days longer in rape and soybeen seedcake mixture. Also there wad no primodia and fruitbody formation at soybeen seedcake mixture which had highest T-N content among the other mixed substrates. Yield per bottle and biological efficiency were highest of 144.6 g and 75.4%, respectively at kapok seedcake mixture. As a result, this study found that cotton seedcake can be replaced with kapok seedcake in bottle culture of oyster mushroom.
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