• Journal of Korean Society on Water Environment
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• v.20 no.4
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• pp.357-364
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• 2004

In this study, biodegradable organic matter was divided into a rapidly biodegradable fraction($BDOC_{rapid}$) and a slowly biodegradable fraction($BDOC_{slow}$) for various waters with different types of DOC. These fractions($BDOC_{rapid}$ and $BDOC_{slow}$) were defined by using a shaking incubation method modified from Carlson's method. Also, in this study, optimum incubation time and accuracy were investigated to determine $BDOC_{rapid}$ and $BDOC_{slow}$. When suspended bacteria obtained from raw water and BAC effluent, or attached bacteria from BAC was respectively used as an inoculum, the difference in total BDOC($BDOC_{total}$) was minimal. Therefore, total BDOC was determined in 7~8 days by the shaking method, which is comparable with Servais's method by which BDOC was determined in 28 days. In addition, the difference of BDOC between these two methods was within 7%. Although $BDOC_{rapid}$ and $BDOC_{slow}$ were effectively determined by a method defined by Klevens, the difference in optimal incubation time was significant for different water samples. However, when using the shaking method, optimal incubation time for $BDOC_{rapid}$ was found to be 3 days, therefore, the $BDOC_{rapid}$ was defined as the difference between $DOC_0$ and $DOC_{3days}$, and $BDOC_{slow}$ was defined as the difference between $BDOC_{total}$ and $BDOC_{rapid}$. As a conclusion, for determining the fraction of BDOC using the shaking method, the concentrations of an inoculurns and optimal incubation times used in this study were very effective.

• Restorative Dentistry and Endodontics
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• v.34 no.6
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• pp.491-499
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• 2009

This study examined the influence of the storage methods on the viability of oral epithelial cells using conventional cell freezing storage, slow freezing preservation, rapid freezing preservation, and slow freezing preservation with a pressure of 2 Mpa or 3 Mpa. The cell viability was evaluated by cell counting, WST-1 and the clonogenic capacity after 6 days of freezing storage. After 6 days, the frozen cells were thawed rapidly, and the cell counting. WST-1, and clonogenic capacity values were measured and compared. 1. The results from cell counting demonstrated that conventional cryopreservation, slow freezing under a 2 Mpa pressure and slow freezing under a 3 Mpa pressure showed significantly higher values than slow freezing preservation and rapid freezing preservation (p < 0.05). 2. The results from the optical density by WST-1 demonstrated that slow freezing under a 2 Mpa pressure showed significantly higher values than slow freezing preservation and rapid freezing preservation (p<0.05). 3. The clonogenic capacity demonstrated that slow freezing under a 2 Mpa pressure showed significantly higher values than slow freezing preservation and rapid freezing preservation (p < 0.05).

• Clinical and Experimental Reproductive Medicine
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• v.26 no.2
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• pp.127-135
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• 1999

Cryopreservation is able to store the surplus pre-embryos for freezing and furthermore thawing and transfer in a subsequent cycle. Cryopreserving cells which are maintaining their viability are the very complex process. This study has been carried out in order to find the effects of cryopreservation steps, freezing media and embryonic stages on the rates of viability and development of cryopreserved mouse embryos. Female ICR mice ($6{\sim}8$ weeks old) were induced to superovulate by sequential intraperitoneal injection of 5 IU PMSG and 5 IU hCG 48h apart. Mouse embryos were collected according to its developmental stage after the injection of hCG. Embryos were cryopreserved not only by cryoprotectant step (1 step${\sim}$4 step) but also in a variety of media (HTF, IVF medium, D-PBS) and cell stage. The results were as follows: There is no clear advantage in these freezing media of rapid method, but 4 cell and 8 cell of slow method (2, 3, 4 step) have advantage in D-PBS. The development of embryos according to cell stage become greater in 8 cell stage. In the treatment steps of cryopreservation, the development of embryo to blastocyst was similar among rapid method, but the development of 4 cell and 8 cell embryos to blastocyst according to slow method was better than rapid method.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.21
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• pp.9203-9210
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• 2014

Purpose: To explore associations of CYP2E1 and NAT2 polymorphisms with lung cancer susceptibility among Mongolian and Han populations in the Inner Mongolian region. Materials and Methods: CYP2E1 and NAT2 polymorphisms were detected by PCR-RFLP in 930 lung cancer patients and 1000 controls. Results: (1) Disequilibrium of the distribution of NAT2 polymorphism was found in lung cancer patients among Han and Mongolian populations (p=0.031). (2) Lung cancer risk was higher in individuals with c1, D allele of CYP2E1 RsaI/PstI, DraI polymorphisms and slow acetylation of NAT2 (c1 compared with c2, OR=1.382, 95%CI: 1.178-1.587, p=0.003; D compared with C, OR=1.241, 95%CI: 1.053-1.419, P<0.001; slow acetylation compared with rapid acetylation, OR=1.359, 95%CI:1.042-1.768, p=0.056) (3) Compared with c2/c2 and rapid acetylation, c1/c1 together with slow acetylation synergetically increased risk of lung cancer 2.83 fold. (4) Smokers with CYP2E1 c1/c1, DD, and NAT2 slow acetylation have 2.365, 1.916, 1.841 fold lung cancer risk than others with c2/c2, CC and NAT2 rapid acetylation, respectively. (5) Han smokers with NAT2 slow acetylation have 1.974 fold lung cancer risk than others with rapid acetylation. Conclusions: Disequilibrium distribution of NAT2 polymorphism was found in lung cancer patients among Han and Mongolian populations. Besides, Han smokers with NAT2 slow acetylation may have higher lung cancer risk compared with rapid acetylation couterparts. CYP2E1 c1/c1, DD and NAT2 slow acetylation, especially combined with smoking, contributes to the development of lung cancer. CYP2E1 c1/c1 or DD genotype and NAT2 slow acetylation have strong synergistic action in increasing lung cancer risk.

• Journal of Environmental Health Sciences
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• v.22 no.3
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• pp.103-115
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• 1996

The purpose of this study was to establish acceptable criteria for the design of simple water treatment plant in rural areas. To develop efficient simple water treatment methods for rural areas, water quality in the study areas was investigated and rapid and slow filtrations in pilot-scale were tested under various conditions. The main results of this study are as follows. It was found that the water qualities of the study areas exceed the drinking water standards, which implies that some treatments are required in rural areas. Treatment efficiencies of both rapid sand and dual-media (sand and anthracite) filtration without pre-treatment such as flocculation and sedimentation are very low, which were turned out to be unadequate for the rural areas. Treatment efficiencies of both vertical and horizontal slow filtration without chlorination are very high for consumed $KMnO_4, NH_3-N, NO_3-N$, turbidity, and very low for coliform and bacteria. Treatment efficiencies of both vertical and horizontal slow filtration with chlorination are very high over the most pollutants. A slow filtration with chlorination is efficient for the rural areas. An adequate depth of sand layer is over 60 cm. A horizontal filtration is more economical than a vertical filtration. A horizontal filtration can be operated for a relatively long periods of time without sand washing or replacement because clogging is removed by simple back-washing.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.1146-1152
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• 2005

Now many metropolitan electric railways are being constructed on the metropolitan area. But railways now in service have some inefficiency. These railways are operated like subways, for example, all slow trains and fixed train set. So this paper proposes the methods of improvement. For making rapid train, it is showed ' philosophy of rapid train ' that makes rapid train to be main service. And for effective operation, it is introduced flexible train set and 'separation-unification operation'. And for smart railway tracks, it is introduced making loop track and direct connection track between radiating and circular railways. By these methods, a master plan of improvement of metropolitan electric railways is made and vision of the railways becomes common to passengers.

• Journal of the Korean Society of Food Culture
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• v.18 no.2
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• pp.105-110
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• 2003

This study was conducted to investigate the effect of freezing methods, slow freezing at $-20^{\circ}C$ and rapid freezing at $-70^{\circ}C$, on physical properties of Chinese cabbage in frozen Kimchi during storage at $-20^{\circ}C$. Elasticity of midrib of Chinese cabbage in frozen Kimchi was decreased until 15 days and did not changed thereafter during storage at $-20^{\circ}C$. Hardness of that was not changed during storage. Those results of elasticity and hardness of slow frozen sample are similar to rapid frozen sample. By the morphological observation through transmission electron microscope, more of cellular structure of Chinese cabbage in slow frozen was destructed than that of rapid frozen sample. Drip loss was more in slow frozen sample than that in rapid one.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.8
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• pp.533-540
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• 2012

The concentration of organic compounds was analyzed at each step of BAC (biological activated carbon) process though BDOC (biodegradable dissolved organic carbon) total/rapid/slow. Further, bacteria communities and biomass concentrations measured DGGE (denaturing gradirnt gel electrophoresis) and ATP (adenosine triphosphate) methods were analyzed. The bed volume of steady state is different based on assessment of organic compounds removal. Bed volumes at steady state in DOC, $BDOC_{rapid}$ and $BDOC_{total/slow}$ removal were around 27,500, 15,000 and 32,000, respectively. A biomass didn't change after the bed volume reached 22,500 according to analyzing HPC (heterotrophic plate count) and ATP concentration of bacteria. The concentration of HPC and ATP were $3.3{\times}10^8$ cells/g and $2.14{\mu}g/g$, respectively. The number of the DGGE band were only 5 at the bed volume 8,916, but increased up to 11 at the bed volume 49,632. As operation time increase, bacterial group were more diversity. Four bacteria species including Pseudomonas fluorescens, the uncultured bacterium similar to Acinetobacteria, uncultured Novosphingobium sp. and Flavobacterium frigidarium have detected from the early stages and Proteobacteria group were dominantly detected.

• Journal of Animal Science and Technology
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• v.55 no.5
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• pp.417-425
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• 2013

We sought to provide a method for freezing and preserving primordial germ cells, or an avian germ cell of a bird, as a material for developmental engineering or species preservation. The aim of this study was to compare the efficacy of slow freezing with a vitrification method for the cryopreservation of chicken primordial germ cells (PGCs). PGCs obtained from the germinal gonad of day 5.5-6 day (stage 28) cultured chick embryos, using the MACS method, were classified into two groups: slow freezing and vitrification. We examined the viability of PGCs after Cryopreservation. Four freezing methods were compared with each other, including the following: Method 1: The PGCs were frozen by a programmed freezer in a plastic straw, including 2.0 M ethylene glycol (EG) as cryoprotective additive (slow freezing) Method 2: The PGCs were vitrified in a plastic straw, including 8.0 M EG, plus 7% polyvinylpyrrolidone (PVP) (rapid freezing). Method 3: The slow freezing was induced with a cryotube including 2.0 M EG Method 4: The PGCs were frozen in a cryotube including 10% dimethyl suloxide (DMSO) (rapid freezing). After freezing and thawing, survival rates of the frozen-thawed PGCs from Method 1 to 4were 76.4%, 70.6%, 80.5% and 78.1% (p<0.05), respectively. The slow freezing ($-80^{\circ}C$ programmed freezer) method may provide better survival rates of frozen-thawed PGCs than the vitrification method for the cryopreservation of PGCs. Therefore, these systems may contribute to the cryopreservation of a rare avian species.

• Clinical and Experimental Reproductive Medicine
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• v.28 no.1
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• pp.55-63
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• 2001

Objectives: This study was carried out to evaluate the effects of embryonic stage, cryoprotectant, and freezing-thawing method on the rates of survival and development of the cryopreserved mouse early embryo and finally to establish the cryopreservation method of surplus embryos obtained during assisted reproductive technology (ART). Materials and Methods: Two to eight cell embryos were obtained from oviducts of mated $F_1$ hybrid female mice superovulated by pregnant mare's serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG). Two-step 1,2-propanediol (PROH), dimethylsulfoxide (DMSO) and 4-step PROH DMSO were used as cryoprotectant and dehydration and rehydration method of embryos, and slow-cooling or rapid-cooling method was used as frozen program. The survival rates of embryos were measured after thawing and rehydration, and the developmental rates of embryos were compared and observed during culturing embryos for 24, 48, 72, 96 hrs. Results: As for the survival and development rates of embryos according to embryonic stage, the survival rate of 2 cell stage in PROH and DMSO was significantly higher than 4-8 cell (64.5% versus 62.1 %,79.7% versus 73.2%) (p<0.01, p<0.01), but the development rates of 4-8 cell embryos in PROH and DMSO were significantly higher than 2 cell embryos for whole culture period (p<0.01) and the development rates of 4-8 cell embryos in PROH were significantly higher than 2 cell embryos in DMSO (p<0.01). As for the survival and development rates of embryos according to cryoprotectant, the survival rate of 2 cell embryo in DMSO was significantly higher than that in PROH (74.4% versus 64.5%) (p<0.01), whereas the development rate of embryos was not differ till 24 hrs. The developmen1 rate from morular to hatching blastocyst, however, was significantly higher in PROH than in DMSO during 48 hr (p<0.01). The survival rate of 4-8 cell embryo was 62.1% in PROH and 73.2% in DMSO. The development rates of embryo in PROH were significantly higher for whole culture periods (p<0.01, 0.05). In respect to the effect of freezing and thawing program on the survival and development rates of embryos, method of slow cooling and rapid thawing was more effective than that of rapid cooling and rapid thawing. Conclusions: The survival rate of embryo in 2 cell stage was higher than in 4-8 cell stage, and PROH appears more effective cryoprotectant than DMSO because PROH showed better development rates of embryos in 2 and 4-8 cell stage. Moreover, slow cooling and rapid thawing method was considered as the best cryopreservation program.