In the production of zirconium cladding tube, a pickling acid solution is used to remove surface contaminants, which generates tons of pickling acid waste. The waste pickling solution is a valuable resource of Hf-free Zr. Many studies have investigated separating the Hf-free Zr source from the waste pickling acid. The results showed that Ba2ZrF8 precipitates prepared from the waste pickling acid were useful as an electrolyte for the electrorefining of Zr in molten salt. In the present work, electrorefining was performed in a Ba2ZrF8-LiF binary electrolyte to recover Zr from a Hf-free CuZr ingot anode prepared by electroreduction. Before electrorefining, two pretreatments are performed. First, electrolyte melting was carried out to determine the eutectic temperature, and second, the electrolyte was treated to eliminate impurities, mainly hydride. After electrorefining, the cathode deposits were analyzed by O2 gas analyzer and SEM-EDX to explore the possibility of recovering nuclear-grade Zr metal. Moreover, the anode was analyzed by SEM-EDX to determine the Zr dissolution depth.

Nd-Fe-B permanent magnets have been used in a wide variety of applications because of their high magnetic flux density. So, demand for neodymium has been increasing in worldwide. In this study, an electrowinning process was performed in LiF-NdF3-Nd2O3 high temperature molten salts. However, a corrosion resistant material for use in the molten salt must be found for stable operation because of the harsh corrosion environment of the electrowinning process. Therefore, for this paper, boron nitride(BN), aluminum nitride(AlN), and silicon nitride(Si3N4) were selected as protective and structural materials in the high temperature electrolyte. To investigate the characteristics of BN, AlN, and Si3N4, in molten salts, materials were immersed in the molten salts for 24, 72, 120, and 192 hours. Also, surface condition and stability were investigated by SEM and EDS and corrosion products were calculated by HSC chemistry. As a result, among BN, AlN, and Si3N4, AlN was found to show the best protective material properties.

Skin-derived precursor cells (SKPs) are multipotent, sphere-forming and embryonic neural crest‐related precu- rsor cells that can be isolated from dermis. It is known that the properties of porcine SKPs can be enhanced by leuke- mia inhibitory factor (LIF) which is an essential factor for the generation of embryonic stem cells in mice. In our pre- sent study, to enhance or maintain the properties of murine SKPs, LIF was added to the culture medium. SKPs were treated with 1,000 IU LIF for 72 hours after passage 3. Quantitative real time RT‐PCR was then performed to quantify the expression of the pluripotent stem cell specific genes Oct4, Nanog, Klf4 and c‐Myc, and the neural crest specific genes Snai2 and Ngfr. The results show that the expression of Oct4 is increased in murine SKPs by LIF treatment whereas the level of Ngfr is decreased under these conditions. Interestingly, LIF treatment reduced Nanog exp- ression which is also important for cell proliferation in adult stem cells and for osteogenic induction in mesenchymal stem cells. These findings implicate LIF in the maintenance of stem- ness in SKPs through the suppression of lineage differen- tiation and in part through the control of cell proliferation.

A recent study has reported that pluripotent stem cells can be categorized according to their pluripotent state. The first is a “naïve” state, which is characterized by small, round or dome-shaped colony morphologies, LIF and BMP4 signaling pathways and two active X chromosomes in female; mouse ES cells (mESCs) represent this type. A second “primed” state has also been described and is possible in mouse epiblast stem cells (mEpiSCs) or human ES cells (hESCs). These primed state pluripotent stem cells display flattened monolayer colony morphologies, FGF and Nodal/Activin signaling pathways and X chromosome inactivation in female. It has been suggested that, as a non-permissive species, the porcine species undergoes reprogramming into a primed state during the establishment of pluripotent stem cell lines. Meanwhile, a few studies have reported that primed pluripotent stem cell lines could be reverted to a naïve pluripotent state using various exogenous factors including GSK3β and MEK inhibitors, LIF, hypoxic conditions and up-regulation of Oct3 or klf4. Therefore, the purpose of this study was to investigate whether a LIF-dependent naïve pluripotent stem cell line could be derived from porcine embryonic fibroblasts(PEFs) via doxycycline (dox)-inducible reprogramming factors and LIF. In this study, we have been able to successfully induce PEFs into a LIF-dependent naïve pluripotent-like cell line showing a mESC-like morphology and the expression of pluripotent markers. Our results suggest the possibility of reprogramming to naive pluripotent- like stem cells from PEFs in porcine species. * This work was supported by the BioGreen 21 Program (PJ0081382011), Rural Development Administration, Republic of Korea.

LiF(Mg,Cu,Na,Si) 형광체의 γ선과 β선에 대한 TSEE 특성을 조사하였다. 상(60)Co γ선에 대한 감도는 약 450 counts/mR이었고, 여러 가지 β선에 대한 TSEE 에너지 의존성은 β입자의 평균에너지 0.02MeV에서 0.8MeV 사이에서 ±10%이었다. 그리고 제작된 형광체 앞면에 7mg.cm 상(-2)의 인체 등가물질을 두 면 입사 β입자의 에너지에 무관하게 피부 흡수 선량을 측정할 수 있었다.

LiF(Mg, Cu, P) 단결정의 미시적 이완매개변수와 유전손실 등을 구하기 위하여 TSD glow곡선을 측정하고, 측정된 glow곡선을 초기상승법, 가열율법 및 전면적법으로 해석하였다. 쌍극자의 이완시간 τ, pre-exponential인자 τ하(o) 및 활성화에너지E는 각각 12.19S, 1.97×10 상(-12)S 및 0.55eV이었다. 또한 TSD glow곡선을 사용하여 온도영역 300k~340k 사이에서 구한 LiF(Mg, Cu, P)단 결정의 tanδ값은 약 3×10 상(-2)이었다.

본 연구에서는 LIF의 첨가가 분리된 할구 유래의 생쥐 배아줄기세포 확립에 미치는 영향을 살펴보았다. 과배란 유도된 BDF1 생쥐로부터 2-세포기의 배아를 회수하여 각기 LIF가 첨가되지 않은 배양액과 1,000, 2,500, 5,000 U/mL의 LIF가 첨가된 배양액에서 포배기 배아까지 배양하였다. 배양된 포배기 배아는 차별화 염색 방법을 이용하여 내세포괴와 영양외배엽의 수를 계수하였다. 2,500 U/mL의 LIF 첨가 시 대조군( vs. , P<