• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.51-52
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• 2006

This study was progressed on the freezing behavior of waste water in relation to freeze concentration method useful to waste water treatment system of small and middle size and which can re-use purified water. The object of this experiment is comparing a pollutant contain of the frozen layer and of an aqueous solution by cooling wall temperature, a flow field effect and a initial thickness of frozen layer.

• Clinical and Experimental Reproductive Medicine
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• v.36 no.4
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• pp.311-319
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• 2009

Objective: Human embryonic stem cells (hESCs) have the capacity to differentiate into all of the cell types and therefore hold promise for cell therapeutic applications. In order to utilize this important potential of hESCs, enhancement of currently used technologies for handling and manipulating the cells is required. The cryopreservation of hESC colonies was successfully performed using the vitrification and slow freezing-rapid thawing method. However, most of the hESC colonies were showed extremely spontaneous differentiation after freezing and thawing. In this study, we were performed to rapidly collect of early passage hESCs, which was thawed and had high rate of spontaneously differentiation of SNUhES11 cell line. Methods: Four days after plating, partially spontaneously differentiated parts of hESC colony were cut off using finely drawn-out dissecting pipette, which is mechanical separation method. Results: After separating of spontaneously differentiated cells, we observed that removed parts were recovered by undifferentiated cells. Furthermore, mechanical separation method was more efficient for hESCs expansion after thawing when we repeated this method. The recovery rate after removing differentiated parts of hESC colonies were 55.0%, 74.5%, and 71.1% when we have applied this method to three passages. Conclusion: Mechanical separation method is highly effective for rapidly collecting and large volumes of undifferentiated cells after thawing of cryopreserved early passage hESCs.

• Journal of Food Hygiene and Safety
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• v.39 no.2
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• pp.128-133
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• 2024

Using the freezing removal method, we investigated residual pesticides in 50 grape seed oils distributed in Gyeonggi Province, South Korea. The fat was mixed with acetonitrile and then frozen at ≤-20℃ for 24 h. Fats and oils were removed by separating those in solid state and the extract acetonitrile in liquid state. Ten residual pesticides were detected 161 times in 49 of 50 cases. The detected pesticides were boscalid, cyclufenamide, deltamethrin, difenoconazole, fluxapyroxad, fenpyrazamine, kresoxim-methyl, piperonyl butoxide, tebuconazole, and trifluoxysorbin. Boscalid, a fungicide, was most frequently detected (44 times), followed by fluxapiroxad (35 times). The detection range was 0.01-1.10 mg/kg, which was within the legal limit of residual pesticide for grapes. The recovery rate of the detected pesticides was 72.6-129.8% and the ratio of estimated daily intake/acceptable daily intake was calculated to determine the risk of the detected pesticides, which was <0.0028%. This indicated that the risk caused by pesticide residues in grape seed oil is at a safe level.