Two dimensional(2D) crystals, composed of a single layer or a few atomic layers extracted from layered materials are attracting researchers’ interest due to promising applications in the nanoelectromechanical systems. Worldwide researchers are preparing devices with suspended 2D materials to study their physical and electrical properties. However, during the fabrication process of 2D flakes on a target substrate, contamination occurs, which makes the measurement data less reliable. We propose a dry transfer method using poly-methyl methacrylate(PMMA) for the 2D flakes to transfer onto the targeted substrate. The PMMA is then removed from the device by an N-Methyl-2-pyrrolidone solution and a critical point dryer, which makes the suspended 2D flakes residue free. Our method provides a clean, reliable and controllable way of fabricating micrometer-sized suspended 2D nanosheets.

솔껍질깍지벌레(Matsucoccus thunbergianae)는 우리나라 곰솔(Pinus thunbergiane)림의 주요 해충중의 하나이다. 솔껍질깍지벌레는 단목 (丹木)마다 밀도에 차이가 있고, 수관 내 가지별로도 밀도차이가 있어 예찰이 어렵다. 따라서 본 연구는 황색 끈끈이트랩을 이용하여 솔껍질깍지 벌레의 분포나 발생을 예찰할 수 있는 방법을 제시하기 위하여 수행되었다. 곰솔림에서 끈끈이 트랩에 유인된 솔껍질깍지벌레 수컷 성충의 밀도와 가지 내 약충의 밀도는 높은 상관관계를 보였다. 끈끈이트랩에 유인된 솔껍질깍지벌레 수컷성충의 밀도는 곰솔의 상층부가 하층부보다 높았으나 통계적 차이는 없었다. 곰솔 가지의 단위면적당 솔껍질깍지벌레 밀도는 흉고직경이 클수록 높아지는 경향을 보였으며 1~2.5 cm 사이의 굵기 내에서는 통계적 차이가 없었다. 곰솔 가지의 방향이 지면을 향하는 쪽이 반대 방향을 향하는 쪽에 비하여 솔껍질깍지벌레의 밀도가 높았다. 솔껍 질깍지벌레의 예찰에 끈끈이 트랩의 사용을 제안하며, 가지에서의 밀도는 2~2.5 cm 굵기의 가지를 선택하여 지면쪽의 밀도 조사를 추천한다.

The electronic and optical characteristics of molybdenum disulphide (MoS2) film significantly vary with its thickness, and thus a rapid and accurate estimation of the number of MoS2 layers is critical in practical applications as well as in basic researches. Various existing methods are currently available for the thickness measurement, but each has drawbacks. Transmission electron microscopy allows actual counting of the MoS2 layers, but is very complicated and requires destructive processing of the sample to the point where it will no longer be useable after characterization. Atomic force microscopy, particularly when operated in the tapping mode, is likewise time-consuming and suffers from certain anomalies caused by an improperly chosen set point, that is, free amplitude in air for the cantilever. Raman spectroscopy is a quick characterization method for identifying one to a few layers, but the laser irradiation causes structural degradation of the MoS2. Optical microscopy works only when MoS2 is on a silicon substrate covered with SiO2 of 100~300 nm thickness. The last two optical methods are commonly limited in resolution to the micrometer range due to the diffraction limits of light. We report here a method of measuring the distribution of the number of MoS2 layers using a low voltage field emission electron microscope with acceleration voltages no greater than 1 kV. We found a linear relationship between the FESEM contrast and the number of MoS2 layers. This method can be used to characterize MoS2 samples at nanometer-level spatial resolution, which is below the limits of other methods.

The unique characteristics of graphene make it an optimal material for crucial studies; likewise, its potential applications are numerous. Graphene’s characteristics change with the number of total layers, and thus the rapid and accurate estimation of the number of graphene layers is essential. In this work, we review the methods till date used to identify the number of layers but they incorporate certain drawbacks and limitations. To overcome the limitations, a combination of these methods will provide a direct approach to identify the number of layers. Here we correlate the data obtained from Raman spectroscopy, optical microscopy images, and atomic force microscopy to identify the number of graphene layers. Among these methods, correlation of optical microscopy images with Raman spectroscopy data is proposed as a more direct approach to reliably determine the number of graphene layers.

To investigate skin-whitening effect of Adenophora triphylla var. japonica sprout extract, antioxidant activity, inhibitory effect on tyrosinase and melanin synthesis in B16/F10 melanoma cell were examined. Total phenolic content (246.25 ㎎ GAE/g) and total flavonoid content (303.94 ㎎ RE/g) of ethyl acetate fraction from Adenophora triphylla sprout (EFAT) showed the highest contents than other fractions (n-hexane, chloroform and distilled water). Antioxidant activities of EFAT has been evaluated using ABTS, DPPH radical scavenging activities, FRAP and inhibitory effect of lipid peroxidation. EFAT showed excellent radical scavenging activity and inhibitory effect on MDA production. Inhibitory effect of tyrosinase as a major enzyme of melanin synthesis was also measured. In these results, EFAT showed higher inhibitory effect against L-DOPA (51.27%) than L-tyrosine. IC50 value on α-glucosidase was 41.93 ㎍/㎖. In B16/F10 melanoma cells, EFAT inhibited melanin synthesis at 200 ㎍/㎖ concentration (about 42% decrease). Finally, main physiological compounds of EFAT were identified as a rutin and a chlorogenic acid using high performance liquid chromatography.

Background : The organic matter content of land clearing or soil brought from an other place is very low, less than 0.5%. However, the organic matter content of natural habitat soil and leader farmhouse soil was two to three times higher than that of general farmhouse soil. As a result, the yield of Gastrodia elata was higher than that of general farmhouse. Therefore, this experiment was carried out to investigate the yield of G. elata according to the application of green manure crops (GMCs). Methods and Results : This experiment was carried out in a soil with organic matter content of 0.5% in rain shelter greenhouse. The kind of GMCs are corn, Sudan grass, sorghum and oats, and the throughputs per 10 a were 2,000 ㎏, 2,200 ㎏, 1,500 ㎏ and 700 ㎏ of each. The soil preparation was carried out after treated of GMCs at least one month before G. elata was formally planted. As the results of these experiment, organic matter content in soils increased 4 - 5 times compared with before treatment. As a result, the yield of G. elata increased by 21 - 41% in all treatments of GMCs. In addition, there was 2 - 5% more G. elata of good merchantable quality. However, the soil temperature in the summer season period of 2016 (7.1 - 8.31) was 1.2 - 1.6℃ higher than the previous year. The day when the outside temperature was above 30℃ was 41 days. It doubled from the previous year. Soil moisture content showed similar tendency according to treatments. As a result, 20 - 30% of high temperature damage and 20 - 50% of putrefaction occurred, and the total yield also decreased by 20 - 30% compared to normal year. Conclusion : In conclusion, some organic matter is needed for cultivation of G. elata. Therefore, it is considered that it would be better to keep the organic matter content at 2 - 3% when the destination are managed, and to use corn or Sudan grass as the GMCs.