We define hydrogel as a polymer network containing a large amount of water or biological fluid in a 3-D structure. Because of the physical or chemical chains present in a hydrogel, it is stable in aqueous environment. Therefore, it has been used in diverse medical fields. In addition, by controlling the gelation degree of polymer solution (the state prior to hydrogel) hydrogels can be easily applied to damaged tissue area. This unique structure and properties of hydrogel shares a similarity with ECM (Extracellular matrix) in that it has a potential to be applied in tissue engineering field. Especially, the injectable property and ECM like structure can be applied to bone regeneration. Out of several polymers can be form hydrogels, silk fibroin (SF) has an excellent biocompatibility, biodegradability and it can be used to create bone regeneration scaffold in the form of hydrogel. In this study, we fabricated a SF hydrogel containing hydroxyapatite nanoparticle (HAp). To improve the dispersibility of HAp in the SF aqueous solution, we chemically modified the surface of HAp particles using hyaluronic acid (HA) – dopamine (DA) conjugate. Since SF aqueous solution has a long term gelation time, we utilized ultra-sonication method to induce a rapid gelation. Stability of HAp in SF aqueous solution was measured by ELS and TGA. Finally, FT-IR and WAXD were used to evaluate the changes of secondary structure of silk hydrogel according to concentrations of hydroxyapatite nanoparticle concentration.

Root knot nematode species, such as Meloidogyne hapla, M. incognita, M. arenaria and M. javanica are economically most notorious nematode pests, causing serious damage to the various crops throughout world. In this study, DNA sequence analyses of the D1-D3 expansion segments of the 28S gene in the ribosomal DNA were conducted to characterize genetic variation of the four Meloidogyne species obtained from Korea and United States. PCR-RFLP (Polymerase Chain Reaction-Restriction Fragment Length Polymorphism), SCAR (Sequence Characterized Amplified Region) marker and RAPD (Random Amplification of Polymorphic DNA) also were used to develop the methods for exact and rapid species identification. In the sequence analysis of the D1-D3 expansion segments, only a few nucleotide sequence variation were detected among M. incognita, M. arenaria, and M. javanica, except for M. hapla. The PCR-RFLP analysis that involves amplification of the mitochondrial COII and lrRNA region yielded one distinct amplicon for M. hapla at 500 bp, enabling us to distinguish M. hapla from M. incognita, M. arenaria, M. javanica reproduced by obligate mitotic parthenogenesis. SCAR markers successfully identified the four root knot nematode species tested. We are under development of RAPD primers specific to the three root knot nematodes found in Korea.

본 연구는 사용 후 핵연료의 금속전환 공정에서 발생되는 폐용융염을 고형화하는 방법으로 실리카 함유 무기물을 이용하여 폐용융염을 열적, 수화학적 안정한 화합물로 전환하는 방법을 제안하였다. 실리카 함유 무기물(SAP)은 일반적인 sol-gel process로 합성되었으며, 및 로 구성된다. 제조된 SAP을 에서 폐용융염과 반응시켜 각 금속염화물에 대한 반응특성 및 열안정성을 조사하고, PCT 침출시험법을 이용하여 수화학적 안정성을 평가하였다. LiCl은 와 로, CsCl는 CS-aluminosilicate와 로, 는 로, 는 로 전환되었다. 9시간 동안 반응시킨 후, 금속염화물의 전환율은 였으며, 까지 열감량은 1wt%이하로 TGA(Thermo Gravimetric Analysis)로 확인하였다. Cs 및 Sr의 침출속도는 로 매우 높은 내침출특성을 나타내었다. 이상의 결과로부터, SAP으로 명명된 안정화제(stabilizer)는 금속염화물로 구성된 폐용융염에 대해 매우 효과적인 것으로 판단된다. SAP을 이용한 폐용융염의 고화처리방법은 후속적인 안정성의 검증과정을 통하여 폐용융염의 최종처분부피를 최소화할 수 있는 대안적인 고화방법으로 고려될 수 있을 것으로 기대 된다.