• The Plant Pathology Journal
• /
• 제20권2호
• /
• pp.103-105
• /
• 2004

A destructive stem rot of strawberry (Fragaria x ananassa cv. Akihime) sporadically occurred in farmers' fields in Daegok-myon, Jinju city, Gyeongnam province in Korea. The infected plants showed stem and crown rot, with occasional blighting of the whole plant. White mycelia appeared on stems of infected clones and sclerotia formed on the old lesions near soil surface. The fungus formed white colony on PDA and showed maximum mycelial growth and sclerotial formation at $30^{\circ}C$. The fungus usually have many narrow hyphal strands, 2.6-10.0 $\mu\textrm{m}$ in width, in the aerial mycelium. Typical clamp connections were formed on the mycelium. Sclerotia were spherical and 1.0-2.4 mm in size. The fungus was repeatedly isolated from infected tissues and identified as Sclerotium rolfsii. Its patho-genicity was confirmed when inoculated onto straw-berry. This is the first report on the stem rot of strawberry caused by S. rolfsii in Korea.

• Archives of Pharmacal Research
• /
• 제28권7호
• /
• pp.745-749
• /
• 2005

A simple synthetic route for the synthesis of novel methyl branched cyclopropyl phosphonic acid nucleosides is described. The characteristic cyclopropyl moiety 8 was constructed by employing Simmons-Smith reaction as a key step. The condensation of mesylate 11 with natural nucleosidic bases (A,C,T,U) under standard nucleophilic substitution conditions ($K_2CO_3$, 18-Crown-6, DMF) and after subsequent hydrolysis resulted in the formation of target nucleosides, 16, 17, 18, and 19. In addition, the antiviral evaluations of the synthesized nucleotides against various viruses were also performed.

• 한국환경과학회지
• /
• 제1권1호
• /
• pp.69-76
• /
• 1992

The effects of $Ca_{2+}$ ion on the formation of micelle colloid of nonionic surfactants, nonylphenol-(ethylene oxide)n [NP-(EO)n: n= 11, 40, 100) were investigated by the iodine solubilization method. The characteristics of spectra depended on the concentration of $Ca_{2+}$ ion and the number of EO unit. Above CMC(critical micelle concentration), the intensity of the CT (charge transfer) band by the addition of $Ca_{2+}$ ion for the NP-(EO)11 and NP-(EO)40 increased and when decreased and for the NP-(EO)In continuously increased. The increase in the intensity of CT band were attributed to the compactness of micelle in the presence of $Ca_{2+}$ ion. These phenomena may be explained by the fact that the linear ethylene oxide (EO) chain, relatively free to assume various configuration in aqueous solution, could form a pseudo-crown ether structures capable of forming complexes with $Ca_{2+}$ ion.

• Bulletin of the Korean Chemical Society
• /
• 제23권5호
• /
• pp.688-692
• /
• 2002

The aminomethylation of phenols with para-substituents by the Mannich reaction has successfully been accomplished to produce the Mannich bases 2-6. The compounds 7-8 have also been synthesized in order to identify the effect of the side arms and t he macrocycle in the complex formation. Protonation constants and stability constants of the double armed diaza-18-crown-6 ethers 2-7 with metal ions have been determined by potentiometric method at 25 $^{\circ}C$ in 95 % methanol solution. Under a basic condition (pH > 8.0), the double-armed crown ethers 2-6 revealed stronger interaction with divalent metal ions than the simple diazacrown ether 1. The stability constants with these metal ions were Co 2+ < Ni2+ < Cu2+ > Zn 2+ in increasing order, which are in accordance with the order of the Williams-Irving series. The stability constants with alkali earth metal ions were Ca 2+ < Sr 2+ < Ba 2+ in increasing order, which may be explained by the concept of size effect. It is noteworthy that the hosts 2-6, which have phenolic side arms and a macrocycle, bind stronger with metal ions than the hosts 1 and 7. On the other hand, the host 8, which has phenolic side arms with a pyperazine ring,provided comparable stability constants to those with the host 3. These facts demonstrate that phenolic side arms play a more important role than the azacrown ether ring in the process of making a complex with metal ions especially in a basic condition. In particular, the log KML values for complexation of divalent metal ions with the hosts 2-6 had the sequence, i.e., 2 (R=OCH3) < 3 (R=CH3) < 4 (R=H) < 5 (R=Cl) < 6 (R=CF3). The stability constants of the hosts 5 and 6 containing an electron-withdrawing group are larger than those of the hosts 2 and 3 containing an electron-donating group. This substituent effect is attributed to the solvent effect in which the aryl oxide with an electron-donating group has a tendency to be tied strongly with protic solvents.

• Applied Biological Chemistry
• /
• 제30권4호
• /
• pp.293-299
• /
• 1987

Bradyrhizobium japonicum ROKS 26 균주를 glycine및 Iysozyme을 처리하여 spheroplast를 형성시킨 후 Agrobacterium tumefaciens에서 분리한 Ti plasmid를 분리하여 형질전환 시키고 octopine 영양 요구성에 의하여 transformants를 분리하였다. 그 결과 Ti plasmid가 도입된 transformants의 형질전환율은 $1{\times}10^{-7}$ 정도 되었다. 얻어진 transformant의 plasmid를 조사한 결과 도입된 Ti plasmid 존재가 확인되었으며, 2차원 전기영동법으로 균체 단백질을 분석한 결과 수용세포인 Bredyrhizobium japonicum ROKS 26과 transformant간의 단백질 구성 차이도 화인되었다. 또한 transformant의 근류 형성력을 조사한 결과 본래의 근류의근류형성력을 가지고 있었으나, crown gall형성에 있어서는 Agrobacterium tumefaciens 15955에 의한 gall보다는 크기에 있어 차이가 있었다.

• 대한치과기공학회지
• /
• 제27권1호
• /
• pp.97-104
• /
• 2005

The effect of Nb on interfacial bonding characteristics of Ni-Cr alloy for porcelain fused to metal crown (PFM) has been studied in order to investigate oxide layer. A specimens, which is 0.8mm in thickness, were fired at 1,000$^{\circ}C$ with four tests such as air, vacuum, air for 5 minutes and vacuum for 5 minutes in order to examine an oxide behavior of alloy surface generated by the adding of Nb to be controlled at a rate of 0, 1, 3 and 5. It observed oxide film form of the fired specimens with optical microscope and scanning electron microscope (SEM), and chemical formation of them with energy disperse X-ray spectroscopy (EDX). The other specimens, which is 2mm in thickness, were fired at 1,000$^{\circ}C$ with air and vacuum in order to analyze the diffusion behaviors of alloy-porcelain interface by X-ray dot mapping. The results of this study were as follows: 1. The observation of microstructure of specimens by SEM showed that the more Nb content is high, the more much intermediate compound of rich Nb is observed. 2. The surface morphology of oxide film is most dense in 3% Nb. The heat treatment in air constitutes denser oxide film than heat treatment under vacuum. 3. The diffusion behavior of oxide layer by X-ray dot mapping showed that Si, Al of porcelain diffuse toward metal.

• 대한치과기공학회지
• /
• 제34권4호
• /
• pp.345-352
• /
• 2012

Purpose: The age-hardening mechanism of an Au-Ag-Cu-Pt-Zn alloy for crown and bridge fabrication was investigated by means of hardness test, X-ray diffraction study and field emission scanning electron microscopic observation. Methods: Before hardness testing, the specimens were solution treated and then were rapidly quenched into ice brine, and were subsequently aged isothermally at $400-450^{\circ}C$ for various periods of time in a molten salt bath and then quenched into ice brain. Hardness measurements were made using a Vickers microhardness tester. The specimens were examined at 15 kV using a field emission scanning electron microscope. Results: By the isothermal aging of the solution-treated specimen at $450^{\circ}C$, the hardness increased rapidly in the early stage of aging process and reached a maximum hardness value. After that, the hardness decreased slowly with prolonged aging. However, the relatively high hardness value was obtained even with 20,000 min aging. By aging the solution-treated specimen, the f.c.c. Au-Ag-rich ${\alpha}_0$ phase was transformed into the Au-Ag-rich ${\alpha}_1$ phase and the AuCu I ordered phase. Conclusion: The hardness increase in the early stage of aging process was attributed to the formation of lattice strains by the precipitation of the Cu-rich phase and then subsequent ordering into the AuCu I-type phase. The decrease in hardness in the later stage of aging process was due to the release of coherency strains by the coarsening of tweed structure in the grain interior and by the growth and coarsening of the lamellar structure in the grain boundary. The increase of inter-lamellar space contributed slightly to the softening compared to the growth of lamellar structure toward the grain interior.

• 한국자원식물학회지
• /
• 제19권5호
• /
• pp.598-601
• /
• 2006

밤나무림내에 sprinkler system을 고정 설치하고, 이를 이용하여 적정한 시기에 일시에 그리고, 간편하게 약제를 살포함으로써 밤나무의 주요해충인 밤나무흑벌(Dryocosmus kuriphilus)의 피해를 효과적으로 방제할 목적으로 2003년부터 2년간 경남 산청군 신안면에서 본연구가 수행되었다. 공시약종은 carbaryl 50% WP, 1,500배액을 사용하였으며, 얻어진 결과는 다음과 같다. 밤나무흑벌 성충의 우화시기는 6월 중순부터 7월 중순까지 약35일간이며, 우화최성기는7월상순의 약 5일간이었다. 밤나무흑벌의 우화 및 산란시기에 Carbaryl 50% WP 1,500배액의 수관살포는 밤나무흑벌에 탁월한 방제효과가 있었다. 즉 매일살포구의 평균 충영형성율은 3.0%, 2일간격 살포구의 평균 충영형성율은 12.8%로서 이들은 무처리구의 평균충영형성율 82.9%와 비교하여 각각 96.4% 및 84.5%의 높은 방제효과가 인정되었으며 수관부위별로는 차이가 없었다.

• 대한소아치과학회지
• /
• 제24권4호
• /
• pp.795-804
• /
• 1997

Developmental dental morphological anomalies are fusion, gemination, twinning, concrescence and etc. They may cause many problems in conservative, periodontal and esthetic aspects. Fusion is a condition where two separate tooth buds unite at some stage in their development to form a bifid crown. If tooth contact occurs early, at least before the start of calcification, the two teeth may be completely unites to form a single large tooth. If tooth contact occurs after the time when a portion of the tooth crown has completed its formation, there may be union of the roots only. In fusion the dentin is always confluent. Fusion teeth is more common in the deciduous than in the permanent dentition. Fused teeth are relatively rare, and are mostly mandibular anterior teeth. Fusion of normal and supernumerary teeth or between normal teeth may occurs. The exact etiology factor of fusion is unknown, but genetic and environmental factors seems to be related. A variety of complications and subsequent treatments have been suggested on this teeth. Periodontal conditions may arise due to a groove formed at the line of fusion of the two teeth. Crowding or Protrusion with potential for malocclusion or delayed eruption of adjacent teeth. Fusion teeth appear in the anterior region, they usually cause esthetic problems. Treatments vary depending on the problem, the location, and the extent of fusion. Treatment of fused teeth has been reported from endodontic, orthodontic, periodontic, surgical and multidisciplinary. This report presents the esthetic improvements by separation of two clinical crowns. Bone reduction or endodontic treatments are not required.

• 대한장애인치과학회지
• /
• 제15권1호
• /
• pp.89-93
• /
• 2019

본 증례 보고는 기관 삽관 경험이 있는 조산아에서 상악 유전치의 발육장애가 나타난 증례이다. 본 증례들에서는 기관 삽관으로 인해 치관 형태 이상, 법랑질 결함, 맹출 지연이 나타났다. 또한 치배의 변위로 인한 맹출 경로 이상, 치근 만곡, 후속 영구치의 비정상적인 치근 형성도 나타났다. 이환 치아에 대해서는 예방적 수복치료 및 관리, 적절한 시기에 발치를 고려해야 한다. 소아치과의사는 삽관 경험이 있는 조산아에서 나타날 수 있는 상황에 대해 이해하고, 적절한 개입을 통해 구강 건강 증진을 도모해야 한다.