• Journal of Food Hygiene and Safety
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• v.24 no.4
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• pp.352-356
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• 2009

The purpose of this study was to introduce the toxicological study review to evaluate the safety of PDMS on the 69th JECFA meeting. Polydimethylsiloxane is a polymer and its ADI was established at 23rd JECFA meeting in 1979. The ADI was maintained although the specification was expanded at its 26th, 29 th, 37 th meetings. Recently, it was reported that PDMS with low molecular weight and viscosity has high absorption rate and different toxicity, so it was submitted at 69th meeting. Toxicological studies of PDMS were submitted from the sponsor and additional information is collected from a document searching. The toxicological studies were reviewed in accordance with the 'Guidelines for the preparation of toxicological working papers for the Joint FAO/WHO Expert Committee on Food Additives'. In the available acute, sub-chronic and chronic toxicity studies on PDMS, dose-related increases in incidence and severity of ocular lesions(corneal crystal, inflammation of the corneal epithelium etc.) were consistently observed after oral dosing. It seems to be a local irritant effect, but the mechanism by which the ocular lesions arose is unclear, although the lack of absorption of PDMS indicates that it is unlikely to be a direct systemic effect. Consequently, the relevance of the ocular lesions for food use of PDMS could not be determined. The ADI of PDMS was re-established from 0-1.5 mg/kg bw/day to 0-0.8 mg/kg bw/day by applying additional safety factor 2 based on its ocular toxicity. The result of 0-0.8 mg/kg bw/day is a temporary ADI until further data are provided to 2010.

• Korean Journal of Food Science and Technology
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• v.34 no.3
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• pp.361-364
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• 2002

This study was performed to establish a simple and accurate method for the determination of oxygen that is a processing aid in various beverage. The quantitative determination of dissolved oxygen (DO) contents in 30 cases of samples were performed by traditional titration method and polarography. As a result of the study, the analysis of DO contents in fruit-extract beverages containing oxygen by titration method was time consuming and large sample volumes were needed. Besides, serious interferences with compounds such as hydroxylamine and nitric oxide were observed, leading to false response. Although the polarography is easily affected by $H_2S$, proteins, and various organic compounds, it is a simple and practical method that provides inexpensive and relatively rapid analysis. The polarography is best suited to the routine determination of DO in a large number of samples and it is expected that the polarography can directly be applied to the quality control of the beverages containing added oxygen. The analysis results of DO contents in various fruit-extract beverages with oxygen and without oxygen were as follows: 23.10 ppm to 32.60 ppm for various frutis extract beverages with oxygen, 0.70 pp to 2.54 ppm for mixed beverages without oxygen, 7.63 ppm to 8.28 ppm for drinking water.

• The Korean Journal of Quaternary Research
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• v.20 no.1 s.26
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• pp.51-66
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• 2006

The climate of the last glacial maximum (LGM) in northeast Asia is simulated with an atmospheric general circulation model of NCAR CCM3 at spectral truncation of T170, corresponding to a grid cell size of roughly 75 km. Modern climate is simulated by a prescribed sea surface temperature and sea ice provided from NCAR, and contemporary atmospheric CO2, topography, and orbital parameters, while LGM simulation was forced with the reconstructed CLIMAP sea surface temperatures, sea ice distribution, ice sheet topography, reduced $CO_2$, and orbital parameters. Under LGM conditions, surface temperature is markedly reduced in winter by more than $18^{\circ}C$ in the Korean west sea and continental margin of the Korean east sea, where the ocean exposed to land in the LGM, whereas in these areas surface temperature is warmer than present in summer by up to $2^{\circ}C$. This is due to the difference in heat capacity between ocean and land. Overall, in the LGM surface is cooled by $4{\sim}6^{\circ}C$ in northeast Asia land and by $7.1^{\circ}C$ in the entire area. An analysis of surface heat fluxes show that the surface cooling is due to the increase in outgoing longwave radiation associated with the reduced $CO_2$ concentration. The reduction in surface temperature leads to a weakening of the hydrological cycle. In winter, precipitation decreases largely in the southeastern part of Asia by about $1{\sim}4\;mm/day$, while in summer a larger reduction is found over China. Overall, annual-mean precipitation decreases by about 50% in the LGM. In northeast Asia, evaporation is also overall reduced in the LGM, but the reduction of precipitation is larger, eventually leading to a drier climate. The drier LGM climate simulated in this study is consistent with proxy evidence compiled in other areas. Overall, the high-resolution model captures the climate features reasonably well under global domain.