• Korean Journal of Veterinary Research
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• v.24 no.1
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• pp.40-49
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• 1984

To investigate the factors influencing the artifical transformation in Escherichia coli, E. coli C600 was transformed by pBR322 DNA with tetracycline and ampicillin resistant gene purified by CsCl-Etbr equilibrium density gradient centrifugation from E.coli HB 101. The influencing factors in the transformation such as concentration of calcium chloride, time of ice incubation, temperature and time of heat shock, time of gene expression, effects of plasmid DNA concentration and adding time were examined in these experiments. The results obtained were as follows; 1. The highest transformation frequency was observed in the treatments of 100 mM $CaCl_2$ before heat shock and the treatment of $CaCl_2$ was essential step in the process of E. coli transformation. 2. The highest transformation frequency was observed in the treatment of heat shock at $42^{\circ}C$ for 4 min. or $37^{\circ}C$ for 6 min., but the prolonged heat shock resulted a decreased transformation frequency. 3. Treatments of ice incubation at $0^{\circ}C$ for 45 min. before heat stocks or at $0^{\circ}C$ for 30min. after heat shock resulted an increased transformation frequency. 4. There was a linear relationship between DNA concentration and transformation frequency at the concentration of $8{\times}10^3$ recipient cells. The highest transformation frequency reached in carte of 7 mcg of donor DNA, but above 1 mcg of DNA concentration, transformation frequency was not remarkably increased. Addition of donor DNA just after the treatment of $CaCl_2$ was the best. 5. The best condition of gene expression at $37^{\circ}C$ were 40min. for TC-resistant gene and 100min. for AP-resistant gene. TC-resistant gene was higher in the transformation frequency and faster in the gene expression time than AP-resistant gene. In these results, the best conditions for the transformation of E. coli C 600 with pBR322 DNA were: treatment with 100mM $CaCl_2$, ice incubation at $0^{\circ}C$ for 45 min, heat shock at $42^{\circ}C$ for 4 min., 30 min. of ice incubation and incubation at $37^{\circ}C$ for 100min. for gene expression in that order.

• Clean Technology
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• v.29 no.2
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• pp.135-144
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• 2023

Pseudomonas aeruginosa and Staphylococcus aureus are the two most frequently encountered pathogens responsible for chronic wound infections, often coexisting in such cases. These infections exhibit heightened virulence compared to single infections, leading to unfavorable patient outcomes. The interaction among microorganisms within polymicrobial infections has been shown to exacerbate disease progression. Polymicrobial infections, prevalent in various contexts such as the respiratory tract, wounds, and diabetic foot, typically involve diverse microorganisms, with Pseudomonas aeruginosa and Staphylococcus aureus being the most commonly identified pathogens. This study aimed to compare the growth patterns of bacteria under a concentration gradient of toxic chemicals, focusing on a Gram-negative strain of Pseudomonas aeruginosa and a Gram-positive strain of Staphylococcus aureus. The minimum inhibitory concentration (MIC), which signifies the concentration at which bacterial growth is inhibited, was determined by performing broth microdilution and assessing the bacteria's growth curves. The growth curves of both Pseudomonas aeruginosa and Staphylococcus aureus were confirmed, and the exponential growth phases were applied to calculate the doubling times of bacteria. The MIC value for each toxic chemical was determined through broth microdilution. These results allowed for the identification of disparities in growth rates between Gram-positive and Gram-negative bacteria, as well as differences in resistance to individual toxic substances. We expect that this approach has a strong potential for further development towards the innovative treatment of bacteria-associated infections.

• 한국연소학회:학술대회논문집
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• 2004.11a
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• pp.85-90
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• 2004

We have presented characteristics of a transitional behavior from a premixed flame to a triple flame in a lifted flame according to the change of equivalence ratio. The experimental apparatus consisted of a slot burner and a contraction nozzle for a lifted flame. As concentration difference of the both side of slot burner increases, the shape of flame changed from a premixed flame to a triple flame, and the liftoff height is decreased to the minimum value and then increase again. Around this minimum point, it is confirmed a transition regime from premixed flame to triple flame. Consequently, the experimental results of the liftoff height, flame curvature and luminescence intensity showed that the stabilized laminar lifted flame regime is categorized by regimes of premixed flame, triple flame and critical flame. In the visualization experiment of smoke wire, the flow divergence and redirection reappeared in premixed flame as well as triple flame. Thus we cannot express the flame front of lifted flame has a behavior of triple flame with only flow divergence and redirection. To differentiate triple flame and premixed flame, ${\Phi}$ value of partially premixed fraction is employed. The partially premixed fraction ${\Phi}$ was constant in premixed flame. In critical flame small gradient appears over the whole regime. In triple flame, typical diffusion flame shape is obtained as parabolic distribution type due to diffusion flame trailing.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.1
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• pp.46-56
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• 1994

The characteristics of flows, temperatures, concentrations of the boron are numerically studied when uniform axial magnetic fields are applied in the Czechralski crucible. The to governing factors to the flow regimes are buoyancy, thermocapillarity, centrifugal forces, magnetic forces, diffusion coefficient and segregation coefficient of the boron. Since the concentration of the boron is so low that buoyancy effects are negligible, it cannot affect the flow and temperature fields. From the fact that the flow fields are rotationally symmetric, two velocity components in the meridional plane and the circumferential velocity are calculated together with the temperature in the steady state. Based on the known velocity and temperature distributions the unsteady concentration distributions of the boron are calculated. As the strength of the magnetic is increased, the flow velocities are decreased. Circumferential velocities are large near the crucible side-wall and in the region below the rotating crystal. Steep temperatures gradient near the edge of the rotating crystal causes the Marangoni convection. It has been found out that the convection characteristics affects the unsteady transport phenomena of the boron.

• Ocean and Polar Research
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• v.33 no.2
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• pp.135-147
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• 2011

Zooplankton is an important constituent in assessing ecosystem responses to global warming. The northern East China Sea is an important ecosystem for carbon cycling with a net sink of carbon dioxide. Despite their importance as a major component in carbon cycling, relatively little is known about zooplankton biomass structure and its regulating factors in the northern East China Sea. This study examined zooplankton biomass distribution pattern in the region from multiple cruises encompassing various seasons between 2004 and 2009. Results showed that zooplankton biomass exhibits less cross-shelf gradient in general with declining biomass to the eastern shelf towards the Tsushima Current Water. Size-fractionated biomass showed that the 1.0~2.0 mm size group, mostly copepods, dominated zooplankton biomass, comprising 38 to 48% of total biomass. Smaller zooplankton (0.2~1.0 mm) biomass, consisting mainly of Paracalanus spp, a particle eating herbivorous copepod, was positively related to chlorophyll-a concentration, but no relationship was established for larger zooplankton (1.0~5.0 mm). Spatially-averaged mean total zooplankton biomass was also highly related to chlorophyll-a concentration. These result suggest that the long-term trend of zooplankton biomass increase in this region is partly accounted for by the increases of phytoplankton biomass and productivity underway in the region. However, the underlying mechanisms of how sea surface warming in the study area leads to increased phytoplankton biomass and productivity remains unclear.

• Journal of the Korean Magnetic Resonance Society
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• v.10 no.1
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• pp.105-114
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• 2006

Purpose: We achieved high resolution MR imaging and spectra of human skin in vitro with using a 14.1 T MRI/MRS system, and evaluated the hydration effect of various cosmetic products by measuring the skin's. moisture concentration. Materials and Methods: We used the Bruker 14.1 T MRI/MRS system with a vertical standard bore that was equipped with a DMX spectrometer gradient system (200 G/cm at a maximum 40 A), RF resonators (2, 5 and 10 mm) and Para Vision software. Spin echo and fast spin echo pulse sequences were employed for obtaining the high resolution MR images. The 3D-localized point resolved spectroscopy (PRESS) method was used to acquire the MR spectra. Results: The high resolution MR images and spectra of human skin in vitro were successfully obtained on a 14.1 T system. The water concentration of human skin after applying a moisturizer was higher than that before applying a moisturizer. Conclusions: The present study demonstrated that the high-resolution MR images and spectra of human skin from a high field NMR instrument could be applicable to evaluating the hydration state of the stratum corneum.

• Journal of Conservation Science
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• v.21
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• pp.49-58
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• 2007

Among the treatment results of test samples of the antique lacquer-ware, the treatment with PEG#3,350 40% solution displayed excellent effect with low shrinkage ratio; in weight gain the treatment with Sucrose 19%+Glycerin 1%(t-butanol 5% in water) solution showed consistent increase. However during the impregnation process of Sucrose, the weight of the testing samples decreased by dehydration because the inner part of the test samples and the treatment solution showed concentration gradient. Therefore, we concluded longer impregnation period should be necessary to prevent dehydration. Since both higher and lower molecular weight treatment chemicals could penetrate into the wood of the lacquer-ware, air drying and conditioning after impregnation treatment with high concentration chemicals would be possible, as well as vacuum freeze-drying.

• Journal of Microbiology and Biotechnology
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• v.30 no.7
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• pp.1005-1012
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• 2020

Acid mine drainage (AMD) has been a serious environmental issue that threatens soil and aquatic ecosystems. In this study, an acid-tolerant sulfate-reducing bacterium, strain S4, was isolated from the mud of an AMD storage pond in Vietnam via enrichment in anoxic mineral medium at pH 5. Comparative analyses of sequences of the 16S rRNA gene and dsrB gene involved in sulfate reduction revealed that the isolate belonged to the genus Desulfovibrio, and is most closely related to Desulfovibrio oxamicus (with 99% homology in 16S rDNA sequence and 98% homology in dsrB gene sequence). Denaturing gradient gel electrophoresis (DGGE) analyses of dsrB gene showed that strain S4 represented one of the two most abundant groups developed in the enrichment culture. Notably, strain S4 was capable of reducing sulfate in low pH environments (from 2 and above), and resistance to extremely high concentration of heavy metals (Fe 3,000 mg/l, Zn 100 mg/l, Cu 100 mg/l). In a batch incubation experiment in synthetic AMD with pH 3.5, strain S4 showed strong effects in facilitating growth of a neutrophilic, metal sensitive Desulfovibrio sp. strain SR4H, which was not capable of growing alone in such an environment. Thus, it is postulated that under extreme conditions such as an AMD environment, acid- and metal-tolerant sulfate-reducing bacteria (SRB)-like strain S4 would facilitate the growth of other widely distributed SRB by starting to reduce sulfate at low pH, thus increasing pH and lowering the metal concentration in the environment. Owing to such unique physiological characteristics, strain S4 shows great potential for application in sustainable remediation of AMD.

• YAKHAK HOEJI
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• v.53 no.2
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• pp.51-59
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• 2009

Quantitative analysis of (+)-catechin (C), (-)-epigallocatechin (EGC), (-)-epicatechin (EC), (-)-epigallocatechin gallate (EGCG), (-)-epicatechin gallate (ECG) and caffeine in commercial green tea was carried out by HPLC employing gradient elution of 0.1% acetic acid and acetonitrile on ODS column. The optimized HPLC method provided satisfactory linearity, accuracy and precision. The relationship between the concentration of the components and cultivated region of the commercial green tea was not significant, while the concentration of EGCG, ECG and caffeine decreased significantly in the later harvested green tea samples (p<0.01). Multivariate analysis of the components was performed in order to characterize and evaluate the cultivated region and harvest period-related variation. Hierarchical clustering and discriminant analysis were applied to classify the geographical and seasonal origins of the green tea samples. The classification accuracy of the cultivated region and harvest period by discriminant analysis was 95% and 91%, respectively, indicating that this method could be reliable and convenient for the quality control of herbal products with different origin.

• KSBB Journal
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• v.13 no.1
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• pp.77-82
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• 1998

Glutathione(L-$\gamma$ -glutamyl-L-cysteinylglycine, GSH) produced by microbial enzymes was separated by a liquid chromatography. In order to select a resin which would bind GSH efficiently, a batch adsorption experiment was carried out with GSH solution and various resins at pH 8.0 GSH bound to Q-sepharose and QAE-sephadex among anion exchange resins, but the latter was found not to be suitable because of the reduction of resin volume at high salt concentration. Preliminary experiments using a standard solution were carried out to separate GSH. GSH and $\gamma$ -glutamylcysteine were separated from the other constituents by applying step gradient of salt(NaCl) concentration. GSH was successfully separated from $\gamma$ -glutamylcysteine by applying Tris buffer containing 35mM NaCl. Chromatographic separation behaviors for the enzymatic product was similar to that for the standard solution. Separation yields of GSH from the standard solution and enzymatic product solution were 72.6% and 84.4%, respectively.