Tin dioxide nanoparticles are prepared using a newly developed synthesis method of plasma-assisted electrolysis. A high voltage is applied to the tin metal plate to apply a high pressure and temperature to the synthesized oxide layer on the metal surface, producing nanoparticles in a low concentration of sulfuric acid. The particle size, morphology, and size distribution is controlled by the concentration of electrolytes and frequency of the power supply. The as-prepared powder of tin dioxide nanoparticles is used to fabricate a gas sensor to investigate the potential application. The particle-based gas sensor exhibits a short response and recovery time. There is sensitivity to the reduction gas for the gas flowing at rates of 50, 250, and 500 ppm of H2S gas.

In this study, simple chemical synthesis of green emitting Cd-free InP/ZnS QDs is accomplished by reacting In, P, Zn, and S precursors by one-pot process. The particle size and the optical properties were tailored, by controlling various experimental conditions, including [In]/[MA] (MA: myristic acid) mole ratio, reaction temperature and reaction time. The results of ultraviolet–visible spectroscopy (UV-vis), and of photoluminescence (PL), reveal that the exciton emission of InP was improved by surface coating, with a layer of ZnS. We report the correlation between each experimental condition and the luminescent properties of InP/ZnS core/shell QDs. Transmission electron microscopy (TEM), and X-ray powder diffraction (XRD) techniques were used to characterize the as-synthesized QDs. In contrast to core nanoparticles, InP/ZnS core/shell treated with surface coating shows a clear ultraviolet peak. Besides this work, we need to study what clearly determines the shell kinetic growth mechanism of InP/ZnS core shell QDs.

A multi-step deposition process for the gap-filling of submicrometer trenches using dimethyldimethoxysilane (DMDMOS), (CH3)2Si(OCH3)2, and CxHyOz by plasma enhanced chemical vapor deposition (PECVD) is presented. The multistep process consisted of pre-treatment, deposition, and post-treatment in each deposition step. We obtained low-k films with superior gap-filling properties on the trench patterns without voids or delamination. The newly developed technique for the gapfilling of submicrometer features will have a great impact on inter metal dielectric (IMD) and shallow trench isolation (STI) processes for the next generation of microelectronic devices. Moreover, this bottom up gap-fill mode is expected to be universally for other chemical vapor deposition systems.

MAC-T cells, bovine mammary epithelial cell line, have been utilized to investigate bovine lactation system. A lactogenic phenotype of the cell is generally induced by combination of dexamethasone, insulin and prolactin (PRL). Effect of vitamin A derivative retinoic acid (RA), well reported as an inducer for differentiation in many cells, to MAC-T cell has not been studied. The objective of this study was to confirm effect of differentiation potential by RA treatment in MAC-T cells and to test effect of combination of RA and PRL treatment. In RA or PRL treatment groups, both has induced morphological change to secrete milk of MAC-T cells. Combination of RA and PRL treatment group has presented noticeable lactogenic phenotype among the all group. This phenotype observed at four days after treatment and showed critical morphological change that was rouphly spherical structure at eight days. RA alone treatment showed slightly inhibition of proliferation in the MAC-T cells, but co-treatment with PRL was improved the cell growth more than control group. MTT assay result and Bcl-xL/Bax ratio of mRNA abundance also was entirely consistent with earlier one. RA-induced differentiation of MAC-T cells has increased αs1-casein, αs2-casein and β-casein mRNA expression compared to PRL treatment group. Expression of αs1-casein, αs2-casein and β-casein genes represented the maximum value in the combination of RA and PRL treatment group at four days. The value of each casein gene expression was 4-, 5.5- and 5.9-fold, respectively, as compared with PRL alone treatment in the MAC-T cells. Protein level of β-casein releasing to the medium also induced the highest level at four days. These results provide evidence that RA can induce the differentiation of MAC-T cells and have synergetic effect with PRL.

Ursolic acid is a triterpenoid compound present in many plants. This study examined the antimicrobial activity of ursolic acid against mutans streptococci (MS) isolated from the Korean population. The antimicrobial activity was evaluated by the minimum inhibitory concentration (MIC) and time kill curves of MS. The cytotoxicity of ursolic acid against KB cells was tested using an MTT assay. The MIC90 values of ursolic acid for Streptococcus mutans and Streptococcus sobrinus isolated from the Korean population were 2 μg/ml and 4 μg/ml, respectively. Ursolic acid had a bactericidal effect on S. mutans ATCC 25175 T and S. sobrinus ATCC 33478 T at > 2 × MIC (4 μg/ml) and 4 × MIC (8 μg/ml), respectively. Ursolic acid had no cytotoxic effect on KB cells at concentrations at which it exerted antimicrobial effects. The results suggest that ursolic acid can be used in the development of oral hygiene products for the prevention of dental caries.

This study was carried out to analyze the effect of wind load on the structural stability of a container crane loading/unloading a container on a vessel. The overturning moment of a container crane under wind load at 75m/s velocity was estimated by analyzing reaction forces at each supporting point. And variations of reaction forces at each supporting point of a container crane were analyzed according to the wind load direction and boom shape.

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.

Background : Stevia rebaudiana (Asteraceae), a perennial plant, has been used as a low caloric sweetener and therapeutic agent for diabetes, hypertension, myocardial, and antimicrobial infections. It has been commonly used leaves and stems because of their high anti-oxidative potential. The present research was carried out to explore anti-oxidative and anti-melanogenic effects of aqueous extract of Stevia rebaudiana Bertoni flos in B16F10 cells. Methods and Results : Anti-oxidant activity of Stevia flos extract (SFE) was determined by using 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging assay, nitric oxide (NO) radical scavenging method, and reducing power method. The results showed that the total phenolic content of SFE was 63.154 ± 0.0002 ㎍·QE/100㎎ and the total flavonoid was 8.64 1 ± 0.002 ㎍·GAE/100㎎. SFE exhibited a big significant effect on NO radical scavenging activity (IC50: 179.6 ㎍/㎖) comparing with standard ascorbic acid (IC50: 368.6 ㎍/㎖), and showed concentration dependent DPPH radical scavenging activity (IC50: 131.8 ㎍/㎖). Anti-melanogenic effect of SFE was also examined with B16F10 melanocytes. The amount of melanin synthesis followed by α-melanocyte stimulating hormone on B16F10 cells were significantly reduced in the presence of SFE treatment (p < 0.05). SFE also suppressed the tyrosinase activity (p < 0.05) and α-glucosidase activity (p < 0.05). Conclusion : These results provide evidence Stevia rebaudiana flos has an antioxidant potency and can be used as an anti-melanogenic agent.