Particle size dependence of relaxivity for silica-coated iron oxide nanoparticles

Ahmad, T.,Bae, H.,Rhee, I.,Chang, Y.,Lee, J.,Hong, S. Elsevier 2012 Current Applied Physics Vol.12 No.3

We investigate the particle size dependence of the relaxivity of hydrogen protons in an aqueous solution of iron oxide (Fe<SUB>3</SUB>O<SUB>4</SUB>) nanoparticles coated in silica for biocompatibility. The T<SUB>1</SUB> and T<SUB>2</SUB> relaxation times for various concentrations of silica-coated nanoparticles were determined by a magnetic resonance scanner. We find that the relaxivity increased linearly with increasing particle size. The T<SUB>2</SUB> relaxivity (R<SUB>2</SUB>) is more than 50 times larger than the T<SUB>1</SUB> relaxivity (R<SUB>1</SUB>) for the nanoparticle contrast agent, which reflects the fact that the T<SUB>2</SUB> relaxation is mainly influenced by outer sphere processes. The high R<SUB>2</SUB>/R<SUB>1</SUB> ratio demonstrates that silica-coated iron oxide nanoparticles may serve as a T<SUB>2</SUB> contrast agents in magnetic resonance imaging with high efficacy.

에너지 구조재 적용을 위한 알루미늄/섬유강화 복합재의 표면처리

이경엽(K. Y. Rhee),강용태(Y. T. Kang),양준호(J. H. Yang) 한국표면공학회 2001 한국표면공학회지 Vol.34 No.1

In this work, the surface treatment of aluminum/composites (graphite-epoxy composites) was investigated. The surface of composites was treated by Ar? ion beam under oxygen environment. The surface of aluminum was treated by DC plasma. The optimal condition of surface treatment for the composites was determined by measuring the contact angle as a function of ion dose. The optimal treament condition of the aluminum was determined by measuring the contact angle and T-peel strength as a function of mixture ratio of acetylene gas to nitrogen gas. The mixture ratios used were 1:9, 3:7, 5:5, 7:3, and 9:1 The results showed that the contact angle of composites decreased from 81° to 8° as the ion dose increased from zero to 1×10¹? ion/㎠. The optimal condition of ion dose was 1×10¹?ions/㎠. The results also showed that the contact angle of aluminum was a minimum for the mixture ratio of 5:5. Similarly, the T-peel strength was a maximum for the mixture ratio of 5:5, which indicates that the optimal condition of mixture ratio of acetylene gas to nitrogen gas is 5:5.

한국에서 분리한 agrobacterium tumefaciens T7의 특성과 biovar.결정

이윤,김창진,김성훈,유익동,민태익,Rhee, Y.,Kim, C. J.,Kim, S. H.,Yoo, I. D.,Mheen, T. I. 한국미생물학회 1987 미생물학회지 Vol.25 No.1

For the purpose of securing of strains which can be usefully utilized to study symbiosis between Rhizobium and legume plant, A. tumefaciens T7 was isolated and characterized and then subgroup biovar was determined. A. tumefaciens T7 induced smooth tumor like nopaline type one and did not grow at $37^{\circ}C$ and in the presence of 2% NaCl on yeast extract mannitol medium. The strain was able to grow on the New and Kerr selective media and utilize erythritol but not phenylalanine, tryptophan, and tartarate as a sole carbon source. Negative results were obtained from 3-keto-lactose production and oxidase test. The strain produced alkalifrom malonate and citrate and showed acid litmus milk reaction At least two large plasmids were detected in the cell lysate. According to all of these results, it could be concluded that subdivision of isolated strain was biovar 2.

활성산소원을 이용한 핵사플로오로프로필렌 에폭사이드의 합성

이희우,김훈식,김홍곤,우주영,이태환 한국공업화학회 2001 응용화학 Vol.5 No.2

Hexafluoropropylene oxide(HFPO) is a representative oxygen-containing C₃ fluoromonomer, which enhances physical and chemical properties of fluoro copolymers. It is also essentially used for manufacturing fluorinated ion-exchange membranes such as Nafionⓡ. HFPO was successfully obtained from a liquid-phase epoxidation of hexafluoropropylene with active oxygen species such as NaOCl and H₂O₂. Addition of transition metal halides to the HFP epoxidation was revealed to appreciably enhance the yield of HFPO. Among the transition metal halides used, ferric chloride showed the highest catalytic activity in the epoxidation reactions with both NaOCl and H₂O₂.

단일박대의 자심손실 측정연구

이장로,이용호,신용돌,노태환,강일구 숙명여자대학교 자연과학연구소 1993 자연과학논문집 Vol.- No.4

단일박대형의 연자성 시료의 2 kHz까지의 자심손실을 간편하게 측정하는 장치를 제작하였다. 손실을 측정하는 전력계는 애너로그 곱셈기를 사용하였으며, 시료를 포함하는 NFB 회로에 의하여 자속정현파의 조건을 성립시켰다. 수종의 metglas 시료에 대하여 측정한 결과는 적정한 자장 중 열처리 및 자속정현파의 양 조건하에서 공표치와 좋은 일치를 보였다. A core loss measurement system for single strip soft magnetic materials with frequency range of 2 kHz was built. The analog multiplier by monolithic operational amplifier was used for power loss measurement of samples. The sine flux condition was realized with negative feed back loop including the sample. The measurements were done for several metglas samples and the results showed good agreement with published data under the conditions of sine flux and appropriate annealing.

Effects of Fiber Orientation on Reflectivity and Transmittivity of Microwave for Carbon Fiber Reinforced Epoxy Composites

Shim, H.-B 한국화학공학회 1997 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.35 No.5

뇌실내 수막종 : 2예 보고

임영진,김국기,김태성,김광명,이봉암,임언 대한신경외과학회 1985 Journal of Korean neurosurgical society Vol.14 No.1

The authors present two cases of interesting intraventricular meningiomas. One of these is located in the left lateral ventricle of 26 years old female with no neurologic deficit, which has moderate vascularity. The other case is located in the right "lateral ventricle of 5 years old female with very large size" The preoperative diagnosis should be reached by means of both computerized tomography and carotid angiography. The selection of surgical approach is very important, especially in left lateral ventricular tumor, which is determined by neurologic deficit, vascularity of tumor and tumor size. Total removal has been accomplished by superior parietal approach in left lateral ventricular tumor and right temporal approach in child ventricular meningioma. Literatures concerned were reviewed.

감의 雌雄 配偶體形成에 關한 硏究

李萬相,李重浩,金文泰 圓光大學校 農村副業問題硏究所 1978 農村副業問題硏究 Vol.1 No.-

감의 減數分裂時期, 大小胞子囊, 大小胞子, 雌雄配偶體形成에 對하여 調査하였던바 그 結果는 다음과 같다. 1) 小胞子의 減數分裂은 5月11∼15日 사이에 中期, 4分子期가 된다. 2) 大胞子의 減數分裂은 5月17日前後에 일어난다. 3) 감은 內外珠皮로 되었으며, 珠心組織은 小數의 細胞層으로 되었고, 胚囊의 內被는 規則的으로 되어있다. 4) 完全胚囊이 大部分이지만 減數分裂異常으로 20%程度 異常胚囊이 생기는데, 이것은 먹시 1果당 平均 種子가 8,5個로 80% 結實된것과 一致된다. 5) 小胞子母細胞減數分裂은 大部分正常的이였으나 開花期에 있어서 正常花粉量은 적다. 6) 감에 있어서는 成熟花粉이 되어도 葯內에 융담組織이 殘存하는 것이있다. Present experiment was carried out to examine meiosis time, mega-and microsporangium, mega-and microsprangium, mega-and microspore, and female and male gametophyte formation of persimmon, the results of which were summarized as follows. 1. Metaphase to tatrad stage of meiosis of microspore take place from 11th to 15th. 2. Meiosis of megaspore takes place before and after May 17th. 3. Integument consists of inner and outer integument and nucellar tissue consists of several cell layers and endothelium is regular. 4. Abnormal embryo sac of about 20% is due to irregular meiosis. Accordingly, this accords with the fruit setting of 80% as 8.5 seeds in average per a fruit fo Meogsi, a variety of persimmon. 5. Meiosis of microspore mother cell is mostly regular, but the guantity of normal pollens at flowering time is little. In the persimmon, 6. Tapetal tissue in anther remains some what still till the pollens are mature.

생균제 개발을 위한 새로운 효모균의 선별

신형태,이향우,금동혁,이동권,황보식,이재홍 한국동물자원과학회 2001 한국축산학회지 Vol.43 No.5

A thermotolerant strain of yeasts was isolated from cane molasses at 39℃ from the view of commercial potential of direct-fed microbials (DFMs), and tested for its tolerance to acid in the pH range 1.0∼7.0, bile salts and a mixture of volatile fatty acids (acetic acid: propionic acid: butyric acid= 6.5:2.0:1.5). For comparative purposes, various Saccharomyces cerevisiae strains were also used. The isolated strain DY01 grew very well at up to pH 2.0 and was resistant to high concentrations (0.6%∼0.9%, w/v) of bile salts. Among the strains tested, DY01 showed least inhibition (i.e. 40∼45% inhibition) with 0.25% (v/v) addition of a mixture of volatile fatty acids at 39℃. It appears that this strain, identified as yeast lssatchenkia orientalis. may be used as a potential candidate for a DFM.

원발성 종격동 종양의 임상적 고찰

이수영,강원택,송하숙,이용철,이양근,정근,정은택,유제윤,송호신,김귀완 예수병원 1992 예수병원학술지 Vol.13 No.-