Gyeonggi do, South Korea
Gyeonggi do, South Korea

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Jeong M.S.,R andnter | Cho H.S.,KOR Conformity Laboratories | Cho H.S.,Seoul National University | Park S.J.,R andnter | And 6 more authors.
Food and Chemical Toxicology | Year: 2013

Nano- and microcalcium provided from the KFDA were compared in terms of physico-chemical properties. Calcium samples were tested using EF-TEM and X-ray diffractometry to check for size/morphology and crystal formation, respectively. Two samples of nano- and microcalcium were selected for further evaluation by FE-SEM, DLS (nano-size, 200-500nm; agglomerate, >5μm; micro-size, 1.5-30μm), and electron spin resonance. Both samples were heterogeneous in size, existed as single crystal and aggregated form, and did not generate reactive oxygen species. The specific surface area of nano- and microcalcium measured by N2 Brunauere Emmette Teller method was 12.90±0.27m2/g and 1.12±0.19m2/g, respectively. Inductively coupled plasma optical emission spectrometry analysis revealed the release of 2-3 times more calcium ion from nano- compared to microcalcium at pH 5 and 7. Genotoxicity and acute single-dose and repeated-dose 14-day oral toxicity testing in SD rats performed to evaluate the safety of nanocalcium did not reveal toxicity. However, long-term monitoring will be required for an unequivocal conclusion. A nanocalcium dose of 1g/kg is recommended as the maximum dose for repeated dose 13-week oral toxicity. Further studies could provide details of toxicity of nanocalcium on the repeated dose 13-week oral toxicity test. © 2013 Elsevier Ltd.

Seo J.S.,Inha University | Min B.S.,R andnter | Kwon Y.-B.,R andnter | Lee S.-Y.,R andnter | And 6 more authors.
Journal of Bioscience and Bioengineering | Year: 2016

A human hybrid cell line, F2N78, was developed by somatic fusion of HEK293 and Namalwa cells for the production recombinant biopharmaceutical proteins. In this study, we performed perfusion culture to verify its potential in culture process used for human cell expression platform. Cell viability could be maintained over 90% and high viable cell density was obtained at higher than 1.0 × 107 cells/mL by bleeding process in perfusion culture. The cells were adapted well in both culture modes, but there were apparent differences in protein quality. Compared to fed-batch culture, degalactosylated forms such as G0F and G0 as well as Man5 showed no significant increases in perfusion culture. In terms of charge variants, acidic peaks increased, whereas main peaks constantly decreased according to the length of culture period in both methods. © 2015 The Society for Biotechnology, Japan.

Aydin E.,Koç University | Celebi A.D.,Koç University | Sildir H.,Koç University | Arkun Y.,Koç University | And 3 more authors.
Computers and Chemical Engineering | Year: 2015

Diesel hydroprocessing is an important refinery process which consists of hydrodesulfurization to remove the undesired sulfur from the oil feedstock followed by hydrocracking and fractionation to obtain diesel with desired properties. Due to the new emission standards to improve the air quality, there is an increasing demand for the production of ultra low sulfur diesel fuel. This paper is addressing the development of a reliable dynamic process model which can be used for real-time optimization and control purposes to improve the process conditions of existing plants to meet the low-sulfur demand. The overall plant model consists of a hydrodesulfurization (HDS) model for the first two reactor beds followed by a hydrocracking (HC) model for the last cracking bed. The models are dynamic, non-isothermal, pseudo-homogeneous plug flow reactor models. Reaction kinetics are modeled using the method of continuous lumping which treats the reaction medium as a continuum of species whose reactivities depend on the true boiling point of the mixture. The key modeling parameters are estimated using industrial data. Steady-state and dynamic model predictions of the reactor bed temperatures, sulfur removal, and diesel production match closely the plant data. © 2015 Elsevier Ltd.

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